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Ota, Toshimasa 1956. "Microcellular polyurethane foaming by modified reaction injection molding." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11495.
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Alminderej, Fahad Mohammad. "SYNTHESIS AND CHARACTERIZATION OF POLYURETHANE DENDRIMERS SUBSEQUENT CLICK REACTION." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1469447068.
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Gerry, Neil Leslie. "Mathematical modelling of the reaction and flow of polyurethane foams." Thesis, University of Exeter, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293996.
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Lu, Shiying. "Processing of highly filled polyurethane elastomers by reaction injection moulding." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/28224.
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This study is to investigate the fabrication of filled polyurethane elastomer tiles by the reaction injection moulding (RIM) process. The base matrix is composed of a crosslinked polyurethane elastomer formed by the reaction between a diisocyanate (MDI) and a polyol (polytetramethylene glycol) and crosslinked by trimethylol propane (TMP). The two fillers investigated were barium sulphate and Expancel which were used to dissipate and scatter sonic waves in acoustic damping applications.
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Poudel, Dhruba P. "Late-Stage Modification of Polyurethane Dendrimers Using Click Chemistry." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1627490978861964.
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Zhang, Xiang. "One-pot catalytic reaction of crude glycerin for biopolyols and polyurethane foam production." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306458447.
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Callison, June. "The investigation of a side reaction leading to colour formation in a polyurethane production chain." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2498/.
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In the industrial synthesis of 4,4’-methylene diphenyl diisocyanate (MDI), an unwanted side reaction between the product and the starting material, 4,4’-methylene dianiline, can lead to the formation of ureas. It has been postulated these ureas undergo further reaction with phosgene to produce a precursor to chlorine radicals, which could then attack the MDI backbone forming conjugated systems that would promote colour in the final products. To investigate this process model compounds including 4-benzylaniline (4-BA) and 1,3-diphenylurea were used as starting materials. The reactions carried out showed the phosgenation of the urea forms a chloroformamidine-N-carbonyl chloride (CCC) which upon heating > 303 K can break down to form an isocyanide dichloride (ID). Conventional synthesis routes were used to gain high yields of p-tolyl and phenyl isocyanide dichlorides in order to analyse the compounds. It was found that upon heating to 453 K or irradiating the isocyanide dichlorides in the process solvent (chlorobenzene) coloured solutions were formed; with the presence of MDI and oxygen increasing the intensity of the colouration. Electron paramagnetic resonance spectroscopy was used to gain information on the use of isocyanide dichlorides as a source of chlorine radicals. Using N-tert-butyl--phenylnitrone (PBN) as a spin trap, an 8 line spectra relating to the chlorine adduct was measured confirming the production of Cl•. Throughout the project side reactions involving the formation of carbodiimide from CCC and a secondary route for the phosgenation of the urea to the isocyanate have been investigated and are presented within a global reaction scheme. It was also found the ureas were only partially soluble in the process solvent leading to research into the structure of three different urea molecules and the proposal of a modified reaction scheme.
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Brunson, Kennard. "POLYURETHANE-BASED POLYMER SURFACE MODIFIERS WITH ALKYL AMMONIUM CO-POLYOXETANE SOFT BLOCKS: REACTION ENGINEERING, SURFACE MORPHOLOGY AND ANTIMICROBIAL BEHAVIOR." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2258.
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Concentrating quaternary (positive) charge at polymer surfaces is important for applications including layer-by-layer polyelectrolyte deposition and antimicrobial coatings. Prior techniques to introduce quaternary charge to the surface involve grafting of quaternary ammonium moieties to a substrate or using polyurethanes with modified hard segments however there are impracticalities involved with these techniques. In the case of the materials discussed, the quaternary charge is introduced via polyurethane based polymer surface modifiers (PSMs) with quaternized soft segments. The particular advantage to this method is that it utilizes the intrinsic phase separation between the hard and soft segments of polyurethanes. This phase separation results in the surface concentration of the soft segments. Another advantage is that unlike grafting, where modification has to take place after device fabrication, these PSMs can be incorporated with the matrix material during device fabrication. The soft segments of these quaternized polyurethanes are produced via ring opening copolymerization of oxetane monomers which possess either a trifluoroethoxy (3FOx) side chains or a quaternary ammonium side chain (C12). These soft segments are subsequently reacted with 4,4’-(methylene bis (p-cyclohexyl isocyanate)), HMDI and butanediol (BD) to form the PSM. It was initially intended to increase the concentration of quaternary ammonium charge by increasing PSM soft segment molecular weight. Unexpectedly, produced blends with surface microscale phase separation. This observation prompted further investigation of the effect of PSM soft segment molecular weight on phase separation in PSM-base polyurethane blends and the subsequent effects of this phase separation on the biocidal activity. Analysis of the surface morphology via tapping mode atomic force microscopy (TMAFM) and scanning electron microscopy (SEM) revealed varying complexities in surface morphology as a function of the PSM soft segment molecular weight and initial annealing temperature. Many of these features include what are described as nanodots (100-300 nm), micropits (0.5-2 um) and micropeaks (1-10 um). It was also observed that surface morphology continued to coarsen with time and that the larger features were typically observed in blends containing PSMs with low molecular weight soft segments. This appearance of surface morphological feature correlates with decreased biocidal activity of the PSM blends, that is, the PSM blends exhibit little to no activity upon development of phase separated features. A model has been developed for phase separation and concomitant reduction of surface quaternary charge. This model points the way to future work that will stabilize surface charge and provide durability of surface modification.
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Tremblay-Parrado, Khantutta-Kim. "Synthesis by click chemistry of biobased polyurethane networks with advanced properties." Thesis, Strasbourg, 2020. https://publication-theses.unistra.fr/restreint/theses_doctorat/2020/TREMBLAY-PARRADO_Khantutta-Kim_2020_ED182.pdf.
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Notre époque a connu une révolution avec l'émergence des matières plastiques qui ont désormais une importance inégalée dans notre vie quotidienne. Cependant, ce fort développement entraine de trop nombreux déchets dans l’environnement avec de forts impacts environnementaux et ceci de façon croissante. Pour répondre à cela, l’élaboration de polymères durables avec l'utilisation de ressources renouvelables et des propriétés avancées pour gérer la fin de vie des matériaux est attendue. Le développement de réseaux covalents adaptables (RCA) est apparu comme une alternative intéressante pour répondre à ces attentes en développant des applications dans le domaine des polyuréthanes (PUs) biosourcées. Dans ces travaux, nous utilisons la réaction de Diels-Alder thermoréversible avec un couplage furanne-maléimide pour la synthèse de PUs dérivés d'huiles végétales et des points de réticulation thermoréversibles. Deux nouveaux synthons dérivés de l'huile de tournesol, portant des groupes furane et maléimide, ont été obtenus et incorporés dans des réseaux PU biosourcées. Les réseaux obtenus donnent des résultats prometteurs en termes de propriétés, de recyclabilité thermique et d'autoréparation thermo-induite. Les réseaux PU synthétisés et analysés constituent un tremplin dans le développement de RCA biosourcées à plus faible impact environnementalThe modern era was revolutionized by the invention of plastics and as such have gained prevalence in most aspects of our daily lives, causing an increasing appearance in landfills and oceans. For this reason, sustainable polymer design should not only require the use of renewable resources, but also factor in advanced properties to manage the end-of-life materials for the reduction of energy use, resources and waste. Developing covalent adaptable networks (CANs) has emerged as an interesting alternative to address this problematic, but with little to no application in the domain of biobased polyurethanes. In this work, we utilize the thermoreversible Diels-Alder reaction of the furan-maleimide coupling for the synthesis of vegetable oil derived polyurethanes (PUs) with thermo-reversible cross-linking points. Two new building blocks derived from sunflower oil, bearing furan and maleimide moieties, were obtained and incorporated into the synthesis of biobased PU networks. The obtained PU networks yield promising results in terms of polymer properties, thermal recyclability and heat-induced self-healing. The synthesized PU networks provide a stepping-stone in the development of biobased CANs
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Verhoeven, Vincent Wilhelmus Andreas. "The reactive extrusion of thermoplastic polyurethane." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/292374224.
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Shmelin, George. "A new rheological polymer based on boron siloxane cross-linked by isocyanate groups." Thesis, University of Hertfordshire, 2012. http://hdl.handle.net/2299/13901.
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The research described in this thesis originated from an idea to develop new body protection for the sport of fencing. The ultimate goal is to develop body armour which would be flexible, wearable, washable, light and breathable, offer protection from injuries and cover the entire body of a sportsman. A new material which exhibits shear thickening behaviour has been specially developed for this purpose in the process of this investigation. The material was designed and synthesised as a soft polymeric system which is flexible, chemically stable and able to increase the value of its modulus of elasticity upon impact at a high strain rate, while remaining in its soft gel-like elastomeric state when low strain rate deformation is applied. The polymeric system that has been developed is based on interpenetrating polymeric networks (IPN) of immiscible polyurethane/urea-ester/ether and poly(boron)n(dimethylsiloxane)m (where on average m ≈ 16 n). In addition, as the polydimethylsilane (PDMS) based polymeric system strongly tends to phase separation, the siloxane polymeric network was chemically cross-linked to the polyurethane polymeric network through polyurethane chemical cross-link-bridges. In order to introduce polyurethane cross-links to a siloxane-based polymeric network, some of the attached methyl groups in the PDMS polymeric backbone were substituted by ε-pentanol groups. The resulting polymeric system combines properties of an alternating copolymer with IPN. The actual substitution of the methyl groups of PDMS into alternating ε-pentanol groups was performed by Grignard reaction of trifunctional chlorosilane monomers, magnesium and 1,5-dibromopentane. Chemical analytical techniques like FT-IR, 13C NMR and 1H NMR spectroscopy were used to reveal the chemical structure of the synthesised polymeric network. The mechanical and dynamical properties of the obtained polymeric system were analysed by dynamic mechanical analysis (DMA). This part of the investigation indicated that the novel polymeric system exhibited shear thickening behaviour, but only at a narrow diapason of deformations (i.e., deformations between 2 to 3 % of the length of the sample). At this limited diapason of deformation an effective increase of the modulus of elasticity from 6 MPa (at lower frequencies, i.e., up to ≤6 Hz of the applied oscillating stress) to 65 MPa (at frequencies between 12.5 to 25 Hz) was obtained. However, no increase in the modulus of elasticity was recorded at deformations below 1.5 % or above 3.5 % of length of the sample at the same frequencies (0 to 25Hz) of the applied oscillating stress.
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Wang, Kuan-Jong. "Reactive processing of polyureas and polyurethane-polyester hybrids /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487670346877346.
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Nadal, i. Soy Josep. "Noves aproximacions a la síntesi i caracterització de poliglicols al·lílics, polihidrosiloxans i surfactants copolimèrics. Avaluació d'aquests surfactants en formulacions de poliuretà." Doctoral thesis, Universitat de Girona, 2002. http://hdl.handle.net/10803/8030.
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Els polímers són una sèrie de compostos que troben un ampli ventall d'aplicacions en la indústria actual. Un exemple són les espumes de poliuretà, estructures de tipus cel·lular obtingudes mitjançant la reacció química entre compostos de tipus isocianat i compostos de tipus poliol (polièters amb diferent nombre de grups hidroxil). És imprescindible l'ús d'additius d'estructura tensioactiva (surfactants de silicona) per estabilitzar el procés d'espumació i per proporcionar una estructura cel·lular ordenada i homogènia en mida i distribució. La síntesis i caracterització de les molècules precursores (polihidrosiloxans i polièters al·lílics), l'estudi de la reacció d'hidrosililació com a via d'obtenció dels diferents surfactants per reacció d'addició entre els polihidrosiloxans i els polièters al·lílics i la caracterització i avaluació en formulacions comercials de poliuretà dels surfactants sintetitzats han constituït els objectius del present treball.MEMÒRIA
La Tesi Doctoral ha estat presentada seguint el següent esquema:
CAPÍTOL I. INTRODUCCIÓ A LA QUÍMICA DEL POLIURETÀ.
Es presenten els principis de la química del poliuretà, fent esment dels recents avenços en la síntesis i caracterització d'aquests compostos polimèrics, així com un apartat concret centrat en els surfactants de silicona. Es presenten les estructures habituals d'aquests compostos comercials i es detallen les reaccions de síntesi i les característiques físiques que aquests compostos proporcionen a les espumes de poliuretà.
CAPÍTOL II. OBJECTIUS.
1.- Síntesis y caracterització d'una àmplia gamma de poliglicols al·lílics i de polihidrosiloxans amb grups hidrur reactius, ambdós precursors d'estructures polimèriques de tipus surfactant.
2.- Estudi de la reacció d'hidrosililació com a via de formació d'enllaços Si-C no hidrolitzables, mitjançant la reacció d'addició entre els substrats al·lílics insaturats i els polisiloxans amb grups hidrur reactius.
3.- Caracterització de les estructures polimèriques de tipus surfactant sintetitzades i avaluació d'aquestes en formulacions de poliuretà, a fi de relacionar l'estructura química d'aquests oligómers amb els efectes físics que originen en l'espuma de poliuretà.
CAPÍTOL III. SÍNTESI I CARACTERITZACIÓ DE SUBSTRATS AL·LÍLICS INSATURATS DE TIPUS POLIGLICOL.
S'han caracteritzat per HPLC-UV una sèrie de polietilenglicols comercials. S'ha estudiat la reacció de derivatització al·lílica sobre els grups hidroxil dels polièters comercials (PEG, PPG i copolímers PEG-PPG) i s'han caracteritzat exhaustivament els productes sintetitzats (1H,13C-RMN, GC, GC-MS, FTIR, ESI-MS, HPLC-UV). S'ha iniciat un estudi de polimerització aniònica sobre nous epòxids amb un punt de diversitat molecular, sintetitzant-se i caracteritzant-se els corresponents nous polièters obtinguts.
CAPÍTOL IV. SÍNTESI I CARACTERITZACIÓ DE POLIHIDROSILOXANS REACTIUS.
S'estudia la síntesis de polihidrosiloxans amb grups hidrur reactius, mitjançant la reacció de polimerització aniònica d'obertura d'anell ("AROP, anionic ring opening polimerization") i mitjançant la reacció de polimerització per equilibració catiònica. Es presenta una caracterització exhaustiva dels productes sintetitzats i es descriu la naturalesa de la microestructura polimèrica a partir de la distribució bivariant dels copolímers PDMS-co-PHMS (poli(dimetilsiloxà)-co-poli(hidrometilsiloxà)).
CAPÍTOL V. ESTUDI SISTEMÀTIC DE LA REACCIÓ D'HIDROSILILACIÓ.
S'ha estudiat la reacció d'hidrosililació amb la finalitat de sintetitzar estructures copolimèriques poliglicol-polisiloxà a partir de la reacció de polisiloxans hidrur reactius i polièters al·lílics. S'han provat diferents catalitzadors (Pt/C 5%, cat. de Speier i cat. de Karstedt), s'han sintetitzat diferents estructures tensoactives (lineals i ramificades) i s'ha modelitzat les diferents reaccions secundàries observades, per presentar un estudi mecanístic de la reacció d'hidrosililació aplicada a la síntesis de molècules d'elevat PM a partir de la reacció entre substrats al·lílics insaturats i polihidrosiloxans.
CAPÍTOL VI. AVALUACIÓ DELS SURFACTANTS EN FORMULACIONS DE POLIURETÀ.
S'ha estudiat la idoneïtat dels surfactants de silicona sintetitzats en diferents formulacions de poliuretà comercials. S'ha relacionat el comportament físic d'aquests surfactants en les espumes de poliuretà amb la seva estructura química a partir de l'anàlisi per microscòpia electrònica de rastreig.
CAPÍTOL VII. CONCLUSIONS.
S'han esposat les conclusions extretes de cada capítol.
The present review has been structured in three parts, firstly a general introduction to polyurethane chemistry and the specific role that silicone surfactants develop, secondly a memory that contents a concise description of the PhD Thesis structure and finally the presentation of the results obtained and their discussion.
1.- INTRODUCTION
Polyurethane is one of the most important polymers used in the industry worldwide. The reaction, discovered in 1937 by Otto Bayer, consists in a polyaddition reaction between hydroxyl compounds and isocyanate groups. This reaction forms the new urethane group (strictly a carbamat group) that provide the chemical structure of the polymer. In the presence of different amounts of water, another reaction is involved, between isocyanate groups and water, in order to obtain urea groups. This reaction is very important because, besides generates new polyurea structures it generates carbon dioxide (CO2), the blowing aggent mostly used in the formulations of polyurethane.
Actually, a lot of applications of polyurethane products take advantage on the specific cellular structure that presents, specially flexible foams in mattresses, sofas, seats, rigid foams as insulation panels and semi-rigid foams in the automotive industry. The cellular structure is obtained in the foaming process of the reaction, which involves the generation of a gas (usually CO2 although other compounds like pentane, HCFC's and external CO2 had been used) and the growing of the cell because of the exothermic process. The foaming process is usually an unstable state that needs the participation of a surfactant, a silicone structure that provides the necessary stabilizing capacity in the foaming process. Moreover, another important feature of silicone surfactants is to improve the order and distribution of the cells in the foam.
Generally, the chemical structure of silicone surfactants is co polymeric, consisting in an hydrophobic part composed by the polysiloxane group and an hydrophilic part, usually being made up of different types of polyether structures. This different physical behaviour in the same molecule provides the specific characteristics of silicone surfactants. In order to obtain commercially available surfactants, it has been necessary to study the synthesis and the characterization of the components in the surfactant molecule (the polyether and the polysiloxane groups) and to perform a study of the hydrosilylation, the chemical reaction that generates the co polymeric structure by the reaction between the polyether and the polysiloxane constituents.
2.- PhD THESIS STRUCTURE
The thesis has been organized in seven chapters, being the first of them the introduction to polyurethane chemistry. In the second chapter are exposed the aims of the work. The third chapter is the synthesis and characterization of polyether type unsaturated substrates, the fourth is the synthesis and characterization of reactive polyhydrosiloxanes and the fifth is the systematic study on the hydrosilylation reaction. The evaluation of surfactants in different polyurethane formulations is described in the sixth chapter whereas the concluding remarks have been reported in the seventh chapter.
3.- RESULTS AND DISCUSSION
The first part of this study details the synthesis and characterization of unsaturated polyethers, substrates of the hydrosilylation reaction. Thus, the allylic modification of commercial monohidroxy polyethers has allowed the synthesis of this unsaturated substrates that can react through hydrosilylation reaction with Si-H bonds. In order to obtain new polyether structures, an investigation about the anionic polymerisation of new epoxies has been developed. These new polyether structures have been extensively characterized to estimate the polymerization degree and their molecular weight.
The synthesis and characterization of reactive polysiloxane compounds (containing Si-H bonds in their structure) has been the second aim of this work. In order to obtain these polysiloxane structures, both anionic polymerization of cyclic trisiloxane compounds and cationic polymerization have been studied. Its interesting to emphasize that the results have shown that the microstructure of the copolymeric poly(dimethylsiloxane)-co-poly(hidromethylsiloxane) is statistical in the monomeric distribution (based on MALDI-TOF-MS and 29Si-RMN results), thus the chemical composition along the polymer chain become constant.
Little information has been reported in the literature about the hydrosilylation as source of polymer structures. In order to clarify the synthetic behaviour of the reaction between polysiloxanes with Si-H bonds and allylic polyethers, an exhaustive study of the hydrosilylation as been developed. Different catalysts (Speier's, Karstedt's and an heterogeneous Pt/C 5% have been studied), concluding that the Karstedt catalyst has given the better behaviour.
Finally, the evaluation of the surfactant structures synthesized in different commercially available polyurethane formulations as allowed obtaining a relation between the chemical structure of the silicone surfactant and the physical behavior in the foaming process. SEM has been the technique of choice to better characterize the otained foams.
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Lopes, Gabriel Hoyer. "Síntese de poliuretano termoplástico modificado com POSS via extrusão reativa." reponame:Repositório Institucional da UCS, 2010. https://repositorio.ucs.br/handle/11338/561.
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Neste trabalho, foram sintetizados poliuretanos termoplásticos (TPU) via solução em reator e via extrusão reativa em extrusora dupla rosca. Os TPUs foram obtidos com o uso de pré-polímero 4,4‟-difenilmetano (MDI) e poliol poliéster, a hidroquinona bis-2-(hidróxietil)-éter (HQEE), e o n-fenilaminopropil-POSS. Os reagentes e produtos foram caracterizados através de análises de Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Calorimetria Diferencial de Varredura (DSC), análise Termogravimétrica (TGA) e reometria capilar (exclusivamente para os produtos). As análises de DSC mostraram que a presença do POSS influenciou a entalpia de fusão (ΔHm) dos TPUs sintetizados via solução. As amostras polimerizadas por extrusão reativa a 80 ºC apresentam Tm comparativamente menores que as amostras sintetizadas a 90 ºC, porém com ΔHm superior, indicando que a temperatura possivelmente favorece a formação de um número maior de cristais com um tamanho médio inferior. Também foram observados fenômenos exotérmicos durante o aquecimento das amostras sintetizadas via extrusão reativa, provavelmente devido a disponibilidade de grupos isocianato livres, detectados via FTIR, na região de ~2253 cm-1. A estabilidade térmica dos TPUs via solução também foi alterada pela adição de POSS, enquanto o polímero obtido através da extrusão reativa apresentou valores mais elevados no início da degradação. Os ensaios de TGA em isoterma apresentaram valores de perda de massa progressivamente inferiores nas amostras sintetizadas via extrusão reativa, demonstrando que tanto o POSS quanto a temperatura de síntese influem nas propriedades do polímero. Ensaios de resistência térmica nas amostras apresentaram perdas de massa inferiores nas amostras vi8a xetrusão reativa. Em ensaios de reometria capilar, a inserção do POSS levou a um aumento progressivo da viscosidade intrínseca do polímero, indicando aumento da massa molar média do TPU sintetizado via solução. Os mesmos ensaios executados com as amostras via extrusão reativa mostraram viscosidades aparentes similares, provavelmente influenciados por processos de degradação do material na célula de carga, levando a comportamentos de viscosidade sem uma tendência observável.Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-03T18:10:51Z No. of bitstreams: 1 Dissertacao Gabriel Hoyer Lopes.pdf: 2245249 bytes, checksum: 97ec28c68a7d73e9ca22b258465c50c6 (MD5)
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In this work, thermoplastic polyurethanes (TPU) were synthesized in solution process and reactive extrusion in twin-screw extruder. The TPUs were obtained with the use of pre-polymer based on 4,4´-Methylenediphenyl diisocyanate (MDI) and a polyester functionalized polyol, the bis-2-(hidroxyethyl)ether hidroquinone and the n-phenylaminopropyl-POSS as a second chain extender. The reagents and products were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and also capillary rheometry (only for those products). The DSC analysis presence influenced the melting enthalpy (ΔHm) of the TPU synthesized by solution. The samples synthesized through reactive extrusion at 80 ºC presented a higher Tm compared to the 90 ºC TPUs, with a higher ΔHm, suggesting that the temperature favors the formation of a greater number of crystals with a lower medium size. Exothermic phenomena were observed during the heating of samples synthesized in reactive extrusion, probably due to the availability of free isocyanate groups, which were detected by FTIR in the ~2253 cm-1 region. The thermal stability of the TPUs was enhanced by the addition of POSS, while the polymers obtained through reactive extrusion presented higher onset degradation temperatures. The TGA analysis in isothermal conditions showed progressively lower mass loss values in samples obtained by reactive extrusion, demonstrating that the amount of POSS, as well the synthesis temperature, had influence in the final properties of the TPU. The thermal resistance of samples polymerized in reactive extrusion. In capillary rheometry tests, the insertion of POSS in the polymer led to a progressively higher value of intrinsic viscosity of the TPUs, indicating an increase in the mean molar mass of the TPUs obtained through solution synthesis. The same method was applied to the samples obtained through reactive extrusion, which showed similar apparent viscosities, yet the analysis was probably influenced by the degradation of the TPU inside the loading cell, leading to no measurable tendency in the viscosity of the polymer.
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Sturgess, Craig. "Fully reactive 3D inkjet printing of polydimethylsiloxane and polyurethane." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49659/.
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Additive Manufacturing (AM) encompasses several different technologies, such as inkjet printing, extrusion, and laser melting processes, to selectively transform a processable phase, such as a liquid or powder, to a solid phase, e.g. through solidification, chemical reaction or powder melting and solidification. The geometry is initially defined as a 3D CAD model, which is subsequently ‘sliced’ to create a geometrical representation suitable for the layer-wise manufacturing process. These layers are “printed” in series on a substrate and are additively stacked. Some AM processes can also include multiple materials or voids in this process to increase the design freedom and geometric complexity. With any new process there are challenges, the key one for most AM processes is the limited material selection. Different processes have different material requirements and many current AM materials are sourced from other processes, for example a number of stereolithography processes use materials originally developed as finishes or coatings. The various AM processes have different criteria that must be met for a material to be suitable for processing, such as particle size and distribution, melting temperature and laser absorption in the case of laser-powder bed systems. This PhD is concerned with materials for ink jet printing, a major advantage of this process being the capability to co-deposit different materials. As the materials in jetting are not fed from a single bed or on a platform, there is complete control over material placement. The basic technology behind material jetting is the same as that seen in desktop inkjet printers, and the major challenge in transforming this to a 3D printing method is in materials development. Currently, the process is dominated by fast curing UV based resins, which are primarily acrylate based, and solvent based inks. The solvent inks highlight their 2D printing origins as they have a low material loading resulting in thin layers. These solvent systems are typically used to transport a conductive solute e.g. silver nanoparticles or graphene oxide. The focus of this PhD was to develop new materials for AM jetting by combining reactive components during processing. This process, called Fully Reactive Inkjet Printing (FRIJP), is only possible because of the freedom of material jetting to use multiple materials. In this work two reactions were selected for the development of FRIJP inks. The first was the crosslinking of polysiloxane based polymers (PDMS), the second was the addition polymerisation of polyurethane. These two reactions schemes were chosen because they involve the combination of two different reactive species and produce no unwanted by-products. For the FRIJP of PDMS a commercial two-part chemistry was used that separated the cross-linker and catalyst. When these two components are combined they produce a transparent PDMS rubber. The PDMS was found to have a viscosity that was too high for inkjet printing so a compatible solvent was selected and the concentration modified. Once a printable ink had been created, trials were conducted which involved printing the two components onto a substrate. It was found that by control of the mixing ratio and substrate heating, high reaction rates could be achieved and complex designs could be printed. These designs were then analysed using FTIR and Raman spectroscopy and it was found that there was comparable curing to the bulk mixing. It was also determined that for the selected PDMS there were no issues with substrate mixing which would result in concentration gradients. The second reaction investigated was the addition polymerisation of polyurethane, which involves combination of the diol and diisocyanate. For this work, the inks were developed from monomers that had printable viscosities through thermal modification. However, one ink used did contain a low concentration of solvent. For the polyurethane work the printing environment was controlled to minimise the moisture which could produce unwanted polyurea and amines. The metric used to determine how suitable the inks were for inkjet printing was the molecular weight of the polymer chain. The analysis was conducted using Size Exclusion Chromatography on the printed samples. It was found that after in development, it was possible to achieve an average molecular weight over 20,000, which was identified as the point whereby the polymer printing was successful. This PhD also demonstrates that when printing these two chemistries, the small size of the droplets facilitates complete mixing of the inks. Importantly, with the immiscibility of the polyurethane monomers before reaction, it was found that the small droplet size allowed for the reaction and successive molecular diffusion to achieve the high degrees of conversion required for the production of functional polymers.
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Lee, Yein-ming Leo. "Fundamental studies in reactive processing of polyurethane based polymerizations /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487322984316763.
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Lee, Albert. "Synthesis of polyurethane from one hundred percent sustainable natural materials through non-isocyanate reactions." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53038.
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The synthesis route for the preparation of polyurethane using 100% sustainable materials was proposed. Lignin, one of the most abundance biomass on Earth, was used as one raw material, while the other one used is soybean oil. The reaction occurs in 3 steps, and is done in 2 different pot reactions. Briefly, purchased epoxidized soybean oil is carbonated to synthesize carbonated soybean oil. Then carbonated soybean oil was reacted with coupling agent, 3-aminopropyltriethoxysilane to produce urethane monomers. Finally, prepared urethane monomers were polymerized with lignin to produce sustainable polyurethane. Molecular structures were intensively analyzed using Fourier-Transform Infrared Spectroscopy and Nuclear Magnetic Resonance Spectroscopy. In addition, mechanical properties of prepared polyurethane were analyzed in order to evaluate its performance and compare with the polyurethanes available commercially. Our results indicated that the highest tensile strength achieved was 1.4 MPa, which is slightly below the typical tensile strengths of processible polyurethane. Chemical properties of all the intermediates and products and implications for future research are discussed.
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Gibb, Jack Nicholas. "The competing reactions of polyurethane foam formation : a computational and experimental study." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648568.
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Hsu, Tze-Chien Jeffrey. "Urethane-based IPNs and polyureas in reactive polymer processing /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487331541711679.
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Hadden, Rory. "Smouldering and self-sustaining reactions in solids : an experimental approach." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5587.
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Smouldering combustion governs the burning of many materials in the built and natural environments. Smouldering is flameless, heterogeneous combustion which occurs when oxygen reacts with the surface of a solid fuel. Understanding the conditions which will result in the ignition and smouldering of a porous fuel is important and the phenomena involved are complex and coupled, involving heat and mass transfer, and chemical kinetics. This thesis reports experimental studies of the ignition, spread, suppression and emissions from reactions in porous media. Similar experimental techniques are shown in this thesis to be applicable when studying a wide range of solids which undergo self-sustaining reactions. This thesis is presented in a manuscript style. Each chapter takes the form of an independent paper which has been prepared for journal publication and as such, each chapter can stand on its own as a piece of research. A final chapter summarizes the findings and conclusions and suggests further areas of research. Chapter 1 presents a study of self-sustaining decomposition of ammonium nitrate containing inorganic fertilizer. This is of importance to the shipping industry which transports these materials in large quantities. Upon exposure to a heat source, ammonium nitrate may undergo exothermic decomposition which can propagate through the material, posing safety and economic threats. This reaction does not involve oxygenbased chemistry, but has many similarities to the propagation of a smoulder front in a porous material. Small-scale experiments to investigate the self-sustaining decomposition (SSD) behaviour of NPK (nitrogen, potassium, phosphorous) 16.16.16 fertilizer were undertaken. Experiments showed that this material will undergo self-sustaining decomposition and are used to formulate a reaction framework. Findings were applied to the events that occurred aboard the Ostedijk in 2007. Chapter 2 is a study of smoulder in polyurethane foam to study the relationship between sample size, critical heat flux and spread rate. Smouldering fires are the leading cause of residential fire deaths in developed countries and polyurethane foam is ubiquitous in the modern world. The critical heat flux for ignition was found to decrease with increasing sample size and the spread rate was found to be a function of the sample size, smoulder propagation depth and the applied heat flux. This is the first time that results on the effect of sample size on smouldering have been reported in the literature and these can be used to aid the extrapolation of small-scale flammability testing results to large scale scenarios. Chapter 3 presents an experimental investigation into the ignition of porous fuels by hot particles. This is related to the problem of spotting ember ignition in wildland fires which is a major, but poorly understood, spread mechanism. The process of spotting occurs in wildland fires when fire-lofted embers or hot particles land downwind, leading to ignition of new, discrete fires. The work studies the ignition of a fuel as a function of ember size and temperature. Metal particles are used as a proxy for burning embers and powdered cellulose to represent the forest fuel. Relationships between the size and temperature of the particle required for flaming and smouldering ignitions are found. These results are used to assess the ability of hot-spot ignition theory to determine the particle size–temperature relationship required for ignition of a cellulose fuel bed. Chapter 4 is an investigation into the suppression of smouldering coal. Subsurface coal fires are a significant global problem with fires in China alone estimated to consume up to 200 million tons of coal per year. As global demand for coal increases, accidental fires are a waste of a useful energy resource as well as a source of pollution and greenhouse gases. The results are the first attempt reported in the literature to study the suppression of these fires under controlled laboratory conditions. The ignition, spread and suppression of subsurface coal fires were studied using small-scale laboratory experiments. Time to ignition was seen to depend on particle size with small and large particles resulting in long times to ignition, while medium sized particles resulted in the shortest time to ignition. The maximum temperature, spread rate and mass lost were found to be independent of particle size above a critical particle size. The effectiveness of three systems for delivery of a suppression agent were assessed – direct injection, shower and spray. The effect of particle size on the water required for extinguishing using a spray was found to be weak. Chapter 5 presents an experimental investigation of the smouldering behaviour of peat. This is of particular interest in understanding the impact of smouldering fires on the earth system. The longer burn durations and different combustion dynamics of smouldering compared to flaming means that they have been shown to consume large amounts of biomass in, and contribute significantly to the emissions from, natural fires occurring in peatlands. The dynamics of smouldering peat in shallow, strong fronts was studied in the Fire Propagation Apparatus and a smoulder reaction framework with two burning regimes is presented. The first regime is peat smouldering and was found to be controlled by the applied heat flux and the second regime corresponded to char smouldering and was more sensitive to the flow of oxidizer. Chapter 6 complements Chapter 5 with an analysis of the CO and CO2 emissions for smouldering and flaming peat. This data can be used with large-scale measurement techniques to improve emission estimates. The emissions are found to be dependent of the burning regime and the type of combustion with flaming resulting in higher fluxes of CO2 and lower fluxes of CO compared to peat smouldering. Char smouldering resulted in the highest yields of CO and CO2. The large majority of emissions (85% of CO2 and 97% of CO) are released during the smoulder phase of the reaction. This highlights the differences in the chemical processes occurring under these two modes of combustion. Chapter 7 summarizes the research undertaken in this thesis and presents possible further work.
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Roberts, Sian Louise. "A novel reactive extrusion process for the production of polyurethane adhesives." Thesis, Bangor University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505941.
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Lhomme, Julien. "Nouveaux catalyseurs et systèmes catalytiques appliqués à la synthèse du polyuréthane via la réaction isocyanate – alcool." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0158/document.
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L’objectif de ce travail est de remplacer les catalyseurs organométalliques à base d’étain et de mercure utilisés lors de la synthèse de polyuréthane via la réaction isocyanate – alcool. Une étude bibliographique a montré que la basicité et la nucléophilie d’un catalyseur organique gouvernent son activité et le mécanisme réactionnel qu’il induit. Pour les catalyseurs organométalliques, ces propriétés catalytiques s’expliquent par des considérations électroniques ainsi que par le principe HSAB. D’autre part, une étude approfondie du catalyseur organomercuriel a été menée. Elle a révélé l’intérêt d’ajouter à l’espèce catalytique organométallique un acide carboxylique, de préférence à longue chaîne carbonée. Celui-ci ralentit l’hydrolyse du catalyseur tout en augmentant sa sélectivité envers la réaction isocyanate – alcool. De nouveaux catalyseurs ou systèmes catalytiques originaux ont ensuite été évalués grâce à un test simplifié. Trois catalyseurs organométalliques ont ainsi été sélectionnés pour de nouveaux essais dans des conditions plus proches de celles rencontrées dans l’industrie. Ils se sont tous révélés actifs, mais seul le -dicétonate de zinc II permet d’obtenir un prépolymère incolore et transparent, deux critères essentiels pour les applications visées. Il pourrait donc remplacer le catalyseur organostannique. Enfin, l’étude de la sélectivité de systèmes catalytiques impliquant un catalyseur commercial en présence d’acide néodécanoïque a confirmé le rôle protecteur de ce dernier. La sélectivité du complexe de zinc retenu précédemment a par ailleurs été évaluée et apparaît 2,5 fois supérieure à celle du complexe organomercuriel à remplacerThe aim of this work is to replace organotin and organomercury catalysts used for the synthesis of polyurethane via the isocyanate – alcohol reaction. A bibliographic review revealed that basicity and nucleophilicity of an organic catalyst affect its activity and the reaction mechanism it induces. For organometallic catalysts, these catalytic properties can be explained by electronic considerations and by the HSAB principle. On the other hand, a comprehensive study of the organomercury catalyst highlighted the benefit to combine it with a carboxylic acid, preferably with a long carbon backbone. This slows down hydrolysis of the catalyst while increasing its selectivity toward the isocyanate – alcohol reaction. New original catalysts or catalytic systems were then evaluated using a simplified experiment. Three organometallic catalysts were selected for further testing in conditions closer to industrial ones. They all showed appropriate catalytic activity, but the zinc II -diketonate is the only one to provide a colorless and transparent prepolymer, two essential criteria for the intended applications. This complex could therefore replace the organotin catalyst. Finally, the study of the selectivity of catalytic systems involving a commercial catalyst in the presence of neodecanoic acid confirmed its protective role toward hydrolysis. The previously retained zinc complex was also evaluated and revealed a selectivity 2.5 times greater than that of the organomercurial complex to replace
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Tawa, Tsutomu. "Studies on Reactive Water-Dispersible Polyisocyanate and Polyurethane-Urea Micelle as Coating Materials." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/57280.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第13847号
工博第2951号
新制||工||1436(附属図書館)
26063
UT51-2008-C763
京都大学大学院工学研究科高分子化学専攻
(主査)教授 伊藤 紳三郎, 教授 中條 善樹, 教授 瀧川 敏算
学位規則第4条第1項該当
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Pereira, João Paulo Cardoso Valadares Salvador. "Polímeros reactivos: projecto e síntese de polímeros com funcionalidade isocianato." Doctoral thesis, Universidade de Évora, 2006. http://hdl.handle.net/10174/22622.
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Neste trabalho estudam-se em detalhe os prepolímeros de isocianato e o processo de polimerização que está na base da respectiva síntese e produção. É analisada a cinética, na reacção de polimerização para formação da espuma, a incidência das matérias-primas e da relação estequiométrica de processo no grau de polimerização, bem como as características gerais do prepolímero obtido e da respectiva espuma. Foram projectadas estruturas macromoleculares, com diversas massas moleculares médias e funcionalidades planeadas para duas aplicações concretas na Engenharia Civil, para fundações por agregação do solo e de sistemas expansivos vedantes de perda de água em reservatórios ou barragens. Foram realizados diversos ensaios de caracterização física e qu1m1ca dos prepolímeros e das espumas, de forma a utilizar os prepolímeros desenvolvidos em aplicações na construção civil, nomeadamente na consolidação de solos e na vedação de fendas no betão quando se verifica passagem de água. É ainda apresentado um conjunto de ensaios de aplicação em obra, em diferentes situações, que confirmam o bom desempenho dos prepolímeros desenvolvidos. ⓿⓿⓿ ABSTRACT: lsocyanate prepolymers are studied together with polymerization process used for their synthesis and production. The kinetics is studied in the polymerization reaction for the foam formation, as well as the influence of the raw materials, stoechiometric balance and process conditions on the polymerization reaction and on the characteristics of the obtained prepolymer and foam. Different macromolecular structures were projected, with several average molecular weights and defined functionalities, to be used in two different applications in Civil Engineering, namely foundations by soil aggregation and Water leakage sealant expansion systems to use in Dams and reservatoires. A set of physical and chemical characterization tests were performed on the developed prepolymers and foams, to test the synthesized prepolymers in different applications in civil engineering, mainly in soil consolidation and in concrete sealing of the water passage. A set of application tests were performed, in different conditions, to confirm the good performance of the developed prepolymers.
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Ornaghi, Felipe Gustavo. "Nanocompósitos TPU/OMMT : processamento reativo e caracterização." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/98999.
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Neste trabalho foram obtidos nanocompósitos contendo 0, 1, 2, 5 e 10% (m/m) de argila organofílica montmorilonita cloisite 30B, contendo terminações hidroxila, por processamento reativo entre um pré-polímero com terminações isocianato e o 1,4-butanodiol, utilizando-se um misturador fechado. Os resultados mostraram que os poliuretanos termoplásticos sintetizados foram obtidos com sucesso. A adição de montmorilonita nos TPUs ocasionou a formação de folhas de argila dispersas de maneira intercalada, parcialmente esfoliada, esfoliada e aglomerados na matriz do TPU. Com a adição da argila houve modificações nos comportamentos de cristalização, estabilidade térmcica e mecanismo de degradação, assim como um aumento nos valores de energia aparente de ativação deste processo. A mobilidade de alguns segmentos poliméricos também foi alterada com a adição da argila. Portanto modificações morfológicas e viscoelásticas foram observadas para os nanocompósitos em dependência da quantidade de argila organofílica empregada, assim como a adição da organoargila alterou o comportamento térmico do poliuretano termoplástico, tornando os nanocompósitos mais suscetíveis a mudanças nos processos de fusão e cristalização em função da exposição a temperaturas elevadas.In this study, were obtained nanocomposites containing 0, 1, 2, 5 and 10% (w/w) of organophilic clay montmorillonite Cloisite 30B, containing hydroxyl terminations, by reactive processing between a prepolymer with isocyanate terminations and 1,4-butanediol, using a closed mixer. The analysis showed that the obtained thermoplastic polyurethanes were synthesized successfully. The addition of the montmorillonite in the TPUs resulted in the formation of sheets of clay dispersed in order intercalated, partially exfoliated, exfoliated and agglomerate in the TPU matrix. With the addition of clay there were changes in the behavior of crystallization, thermal stability and degradation mechanism, as well as an increase in the values of the apparent activation energy of this process. The mobility of certain polymer segments was also changed with the addition of the clay. Therefore viscoelastic and morphological changes were observed in the nanocomposites in dependence on the amount of organophilic clay used, as well as the addition of the organophilic decreased the thermal stability of the thermoplastic polyurethane, making nanocomposites more susceptible to changes in the melting and crystallization processes due to exposure to elevated temperatures.
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Baena, Johanna. "PROCESSING AND KINETIC STUDIES OF THE REACTIVE BLENDS OF POLY(VINYL CHLORIDE) AND THERMOPLASTIC POLYURETHANES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1163727625.
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Haupt, Robert A. "Structural Determination of Copolymers from the Cross-catalyzed Reactions of Phenol-formaldehyde and Polymeric Methylenediphenyl Diisocyanate." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/22025.
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This work reports the elucidation of the structure of a copolymer generated by the cross- catalyzed reactions of PF and pMDI prepolymers. The electronic behavior of phenolic monomers as perturbed by alkali metal hydroxides in an aqueous environment was studied with 1H and 13C NMR. Changes in electronic structure and thus reactivity were related to solvated ionic radius, solvent dielectric constant, and their effect on ion generated electric field strength. NMR chemical shifts were used to predict order of reactivity for phenolic model compounds with phenyl isocyanate with good success. As predicted, 2-HMP hydroxymethyl groups were more reactive than 4-HMP in forming urethane bonds under neutral conditions and 2-HMP hydroxymethyl groups were more reactive than 4-HMP in forming urethane bonds under alkaline conditions.The structure of the reaction products of phenol, benzyl alcohol, 2-HMP, and 4-HMP with phenyl isocyanate were studied using 1H and 13C NMR under neutral organic and aqueous alkaline conditions. Reactions in THF-d8 under neutral conditions, without catalyst, were relatively slow, resulting in residual monomer and the precipitation of 1,3-diphenyl urea from the carbamic acid reaction. The reactions of phenol, 2-HMP, and 4-HMP in the presence of TEA catalyst favored the formation of phenyl urethanes (PU). Reactions with benzyl alcohol, 2-HMP, and 4-HMP in the presence of DBTL catalyst favored the formation of benzyl urethanes (BU). Reactions of 2-HMP and 4-HMP led to formation of benzylphenyldiurethane (BPDU). DBTL catalysts favored formation of BDPU strictly by a benzyl urethane pathway, while TEA favored its formation mostly via phenyl urethane, although some BU was also present. Under aqueous alkaline conditions, 2-HMP was more reactive than 4-HMP, exhibiting an enhanced reactivity that was attributed to intramolecular hydrogen bonding and a resulting resonance stabilization of the phenolic aromatic ring.
ATR-FTIR spectroscopic studies generated real time structural information for model compound reactions of the cross-catalyzed system, differentiating among reaction peaks generated by the carbamic acid reaction, PU and BU formation. ATR-FTIR also permitted monitoring of propylene carbonate hydrolysis and accelerated alkaline PF resole condensation. ATR-FTIR data also showed that the overall reaction stoichiometry between the PF and pMDI components drove copolymer formation. Benzyl urethane formation predominated under balanced stoichiometric conditions in the presence of ammonium hydroxide, while phenyl urethane formation was favored in its absence. Accelerated phenolic methylene bridge formation became more important when the PF component was in excess in the presence of sufficient accelerator. A high percentage of free isocyanate was present in solid copolymer formed at ambient temperature. The combination of ammonium hydroxide and tin (II) chloride synergistically enhanced the reactivity of the materials, reducing the residual isocyanate.
From 13C CP/MAS NMR of the copolymer, the presence of ammonium hydroxide and tin (II) chloride and the higher PF concentration resulted in substantial urethane formation. Ammonium hydroxide favored formation of benzyl urethane from the 2-hydroxymethyl groups, while phenyl urethane formed in its absence. The low alkalinity PF resole with ammonium hydroxide favored benzyl urethane formation. Comparison of these results with the 13C NMR model compound reactions with phenyl isocyanate under alkaline conditions confirmed high and low alkalinity should favor phenyl and benzyl urethane formation respectively. These cross catalyzed systems are tunable by formulation for type of co-polymer linkages, reactivity, and cost.
Ph. D.
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Leadbitter, J. "Structure-property relationships in reaction injection moulded polymers and polymer composites : Structure-property studies of reaction injection moulded polyurethanes, polyesters, polyacrylates and novel acrylic-urethane blends and of composites of these." Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384311.
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Wenning, Christian [Verfasser], Annette M. [Gutachter] Schmidt, and Marc C. [Gutachter] Leimenstoll. "Reaction-Induced Phase Separation of PPG/PEO/HDI based bi-Soft Segment Polyurethanes / Christian Wenning ; Gutachter: Annette M. Schmidt, Marc C. Leimenstoll." Köln : Universitäts- und Stadtbibliothek Köln, 2017. http://d-nb.info/1151638307/34.
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Tahir, Muhammad. "Development of Novel Blends based on Rubber and in-situ Synthesized Polyurethane-urea." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232718.
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Polyurethane and the analogous ‘polyurethane-urea’ are high performance polymeric materials having remarkable properties such as high stiffness, abrasion and tear strengths. In many studies, the low strength rubbers have been blended with various types of polyurethanes for new and improved materials. However, until now, the reported heterogeneous blends offer only a narrow temperature range of application due to the high temperature softening of their polyurethane (-urea) phase. In addition, the conventional solution-or melt-blending methods are time and energy intensive, which tend to forfeit the economical realization of the reported blends. In contrast to earlier studies, a simplified reactive blending process is suggested to synthesize polyurethane-urea via a prepolymer route during blending with rubbers to obtain novel elastomeric materials having extended performance characteristics.
The reactive blending process is opted to prepare blends based on nitrile butadiene rubber (NBR) and in-situ synthesized polyurethane-urea (PUU). The blending is carried out in an internal mixer at a preset temperature of 100°C. The critical temperatures of the reactive blending process are determined from the chemo-rheological analysis of a premix, composed of a 4,4′-diphenylmethane diisocyanate (MDI)/polyether (PTMEG) based prepolymer admixed with 1,3-phenylene diamine (mPD). The prepared NBR/PUU blends exhibit highly improved mechanical properties. Contrary to previous reports, the reinforced dynamic-mechanical responses of the novel blends remain stable till very high temperatures (≥180°C).
The influence of diamine type on the in-situ synthesized polyurethane-urea and the performance of prepared blends are investigated. Four different diamines, namely 1,3-Phenylene diamine, 1,4-Bis(aminomethyl)benzene, 4,4′-Methylene-bis(2-chloroaniline) and 4,4ʹ-(1,3-Phenylenediisopropylidene)bisaniline, are selected to chain extend the prepolymer to PUU during blending with NBR. The chemical and domain structure of the PUUs are found to greatly influence the reinforced tensile and dynamic-mechanical responses of the NBR/PUU 70/30 blends.
The PUU (based on MDI/PTMEG prepolymer and mPD) is blended with polar (CR, XNBR) and nonpolar (NR, EPDM, sSBR) rubbers. PUU compatibilizes with all the rubbers irrespective of their polarity and reinforces their tensile and dynamic-mechanical characteristics. The use of blends in industrial applications, for example, in a truck tire tread compound and as a roller covering material, is examined. In a simplified tire tread formulation, the carbon black for NR-CB composite is partially replaced with an equivalent quantity of PUU for NR/PUU-CB composite of similar hardness. The dynamic mechanical investigations reveal that the energy dissipation and strain dependent softening is high in NR-CB as compared to the NR/PUU-CB composite. In another application, NBR/PUU blend is successfully tested as a rubber roller covering material. The tested blend-covered roller retains its structural integrity and develops less heat build-up as compared to the silica filled NBR-covered roller. This shows a substantial suitability of the blend-covered rollers for film, printing and textile processing machinery.
These novel blends are considered to be the promising new materials for many commercial applications including wheels, rubber rollers, belts or pump impellers.
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Jones, Jacqueline Ann. "Biomaterials and the Foreign Body Reaction: Surface Chemistry Dependent Macrophage Adhesion, Fusion, Apoptosis, and Cytokine Production." online version, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1176223290.
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Hamidi, Abdelmoumen. "Modélisation et simulation du rotomoulage réactif du polyuréthane." Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0016/document.
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Le procédé du rotomoulage réactif est une technologie de fabrication de pièces creuses de taille et géométrie très variés. Une compréhension et une modélisation des phénomènes physiques qui interviennent dans les différentes étapes de la fabrication apportent une contribution importante à la maîtrise de ce procédé. Les travaux abordés dans cette thèse se situent dans le cadre d'un programme plus général visant le contrôle et le pilotage du rotomoulage réactif.Tout d'abord, une caractérisation et modélisation de la cinétique du polyuréthane thermodurcissable en mode dynamique est réalisé suivie par des mesures rhéologiques afin d'établir des lois rhéocinétique ainsi que des lois du comportement viscoélastiques du système réactionnel. Ces lois de comportement sont établies conformément aux conditions réelles de la mise en œuvre du matériau.Ensuite, nous simulons le procédé du rotomoulage en utilisant un code de calcul basé sur la méthode « Smoothed Particle Hydrodynamics » (SPH), développé par notre équipe, en implémentant des nouveaux paramètres physiques: le caractère non-newtonien du mélange réactionnel et les effets de tension superficielle.Le modèle de tension de surface en 2 et 3D développé dans cette thèse permet la détection explicite de l'interface séparant le fluide réactif de l'air. Puis, nous utilisons l'interpolation lagrangienne ou la régression circulaire pour construire la courbe d'interface en 2D et la surface d'interface en 3D sera reconstruite via la régression sphérique. Quant à la modélisation de l'écoulement du fluide non-newtonien, une loi de puissance décrivant l'évolution de la viscosité en fonction du taux de cisaillement a été intégrée dans le solveur pour décrire le caractère non-newtonien du mélange réactionnel durant sa mise en œuvre. Ces paramètres physiques implémentés dans le code ont été validé par une série de cas de tests en 2 et 3D.L'intégration des effets de tension de surface et la prise en compte du caractère non-newtonien du fluide réactif nous ont permis de mieux présenter la mouillabilité de la surface interne du moule et l'étalement des différentes couches du polymères.Mots clés : rotomoulage réactif, polyuréthane thermodurcissable, rhéocinétique, Smoothed Particle Hydrodynamics, tension de surface, fluide non-newtonien, simulationReactive Rotational molding (RRM) is a process for manufacturing hollow plastic products with no weld lines, in virtually any shape, size, color and configuration, using biaxial rotation and high temperature. Understanding and modelling of physical phenomena provide a great contribution for process control that is the purpose of a more general program.Firstly, a characterization and the kinetic modeling of the thermoset polyurethane are performed in anisothermal conditions followed by rheological measurements in order to establish rheokinetik model and the the viscoelastic behavior of the reactive system according with RRM conditions.Afterwards, to simulate the RRM, Smoothed Particles Hydrodynamics (SPH) method is applied which is suited method to simulate the fluid flow with free surface such as occurs at RRM. This solver is developed by our team. Modelling and simulating reactive system flow depend on different parameters; the physical phenomena involved are: surface tension force and non-newtonian fluid behavior.The surface tension method has been successfully applied to simulate RRM using SPH solver taking into account free surface tension force. Surface tension force is given explicitly in the current model. After detecting the boundary particles, the interface is locally fitted by using Lagrangian interpolation polynomial or fitting circle in 2D and by using fitting sphere in 3D, respectively. To study the non-newtonian fluid flow during RRM, a power law describes the evolution of the viscosity versus shear rate was adopted to describe the viscoelastic nature of the reactive fluid during its shaping.The implementation of surface tension and viscoelasticity allows us to present the wettability of internal surface of the mold and the spreading of different polymers layers.Keywords : Reactive rotational molding, thermoset polyurethane, rheokinetik, Smoothed Particle Hydrodynamics, surface tension, non-newtonian fluid, simulation
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Faria, Emanuelle Lima Pache de. "Síntese enzimática de monoésteres de etila catalisada por células íntegras imobilizadas com elevada atividade lipolítica em reator de leito fixo operando em fluxo contínuo." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/97/97137/tde-24032015-171630/.
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Visando ampliar as rotas de produção de biodiesel, o objetivo deste trabalho foi utilizar uma tecnologia alternativa para a produção de biodiesel por via enzimática. Neste processo, células do fungo Mucor circinelloides URM 4182 foram cultivadas em meio apropriado, imobilizadas in situ em espuma de poliuretano e utilizadas diretamente como biocatalisador na síntese de ésteres de ácidos graxos em reações de transesterificação do óleo de coco usando etanol como agente acilante. O trabalho experimental foi desenvolvido em 4 etapas. Inicialmente, as propriedades bioquímicas do biocatalisador foram determinadas, incluindo valores ótimos de pH (7,3) e temperatura (40° C) e constantes cinéticas (Vmax= 610 U/g e Km= 263 mM). Na segunda etapa foram realizados testes utilizando reatores de tanque agitados operados em regime descontínuo confirmando a eficiência do M. circinelloides UMR 4182 para converter os ácidos graxos presentes no óleo de coco em ésteres correspondentes (rendimento de transesterificação da ordem de 96% em 144 horas). Com objetivo de aumentar a produtividade do sistema, na terceira etapa, estudos foram conduzidos em reator de leito fixo operando em fluxo contínuo empregando dois reatores (A e B) com diferentes relações geométricas altura/diâmetro (l/d=4,2 e l/d=14). Avaliou-se inicialmente no reator A o comportamento do sistema para substratos preparados em diferentes razões molares (1:6, 1:8 e 1:10 óleo/álcool). Comparativamente os rendimentos mais elevados (da ordem de 62%) foram obtidos para substratos preparados na razão molar de 1:8 (óleo/álcool), indicando a necessidade de investigar outros parâmetros do processo. A presença de caminhos preferenciais detectada visualmente no reator A pela injeção do corante lipossolúvel indicou limitações de transferência de massa, justificando a baixa conversão em ésteres de etila. Em seguida, mediante a avaliação da geometria dos reatores, foi selecionado o reator B (volume útil - 286 mL) para determinar a influencia do tempo espacial (60, 70 e 80 horas) no desempenho do processo utilizando a condição pré-estabelecida, etanol em excesso na razão molar 1:8 (óleo/etanol). O melhor desempenho do reator foi constatado para tempo espacial de 80h (vazão volumétrica = 0,06 mL.min-1). Nessa condição, 92,7 ??1,5% dos ácidos graxos presentes no óleo de coco foram convertidos nos ésteres de etila correspondentes, alcançando uma produtividade média de 51,0 ??1,4 mgéster.g-1meio.h-1 e fornecendo uma operação estável do sistema por 25 dias. As amostras purificadas apresentaram valores de viscosidade 5,14 mm2/s e teores residuais de monoglicerídeos (3,2 m/m%) e diglicerídeos (3,4 m/m%). Na quarta etapa foram realizados testes em reatores agitados operados em regime descontínuo na presença de solvente (terc-butanol e/ou líquido iônico), em diferentes proporções (10 - 50%). Os resultados foram comparados com a reação conduzida na ausência de solvente que apresentou baixa velocidade de reação e rendimento reduzido (44,5% em 6 dias de reação). Ambos os solventes aumentaram as conversões e velocidades de reação; no entanto, terc-butanol apresentou melhor desempenho em menor proporção (15%). Nessa condição, rendimentos da ordem de 96% foram alcançados em 96 horas, provavelmente devido à polaridade moderada e baixa viscosidade deste solvente que dilui o glicerol acumulado no suporte e melhora a transferência do substrato para o interior das células imobilizadas, impedindo a inibição da enzima por limitação da transferência de massa. De forma geral, os resultados foram promissores e demonstraram a potencialidade das células íntegras de M. circinelloides URM 4182 imobilizada em poliuretano para mediar a síntese de biodiesel em um reator de leito fixo em fluxo contínuo.Aiming at expanding routes for biodiesel production, the goal of this work was to use an alternative technology for the production of biodiesel by enzymatic route. In this case, whole-cells from filamentous fungus Mucor circinelloides URM 4182 were growth in appropriate medium, simultaneously immobilized on low-cost support and used directly as a biocatalyst in the transesterification reactions of coconut oil using ethanol as the acylating agent. The experimental work was carried out in four steps. Initially, the biochemical properties of the immobilized biocatalyst were determined, including values for optimum pH (7.3) and temperature (40 °C) and kinetics parameters (Vmax 610 U/g and Km= 263 mM). Following this, tests were carried out in stirred batch reactors confirming the efficiency of M. circinelloides URM 4182 to produce biodiesel from coconut oil (96% in 144 hours). However, the low productivity attained motivated the replacement of the batch system for packed bed reactor operating under continuous flow using two reactor (A and B) having different geometric relations height/diameter (l/d = 4.2 and l/d = 14). Initially, the performance of the reactor A was assessed for substrates at different molar ratios (1:6, 1:8 and 1:10 oil/alcohol). Comparatively the best conversion (62%) was achieved for substrate at molar ratio of 1:8 (oil/alcohol); suggesting the need to investigate other process parameters to overcome such limitations. The presence of preferential paths visual detected for Reactor A by tracer assay indicated severe mass transfer limitations, justifying the low conversion attained in ethyl esters. Following this, Reactor B was selected to run the continuous experiments using substrate at pre-established condition (molar ratio oil/ethanol 1: 8) under different space times (60, 70, and 80 hours). Better reactor performance was found for space time of 80 h (volumetric flow = 0.06 mL min-1). In this condition, 92.7±1.5% of the fatty acids present in the coconut oil have been converted into the corresponding ethyl esters, reaching an average volumetric productivity of 51.0 ??1.4 mgester.g-1medium.h-1 with no significant reduction in the efficiency during 25 days. The purified samples presented values of 5.14 viscosity mm2/s and residual levels of monoglycerides (3.2 wt %) and diglycerides (3.4 wt%). In the fourth step, transesterification reactions were performed in stirred tank reactors in the presence of solvent (tert-butanol and/or Ionic Liquid) at different proportions (10-50%) in relation to the total weight oil and ethanol. The results were compared with the reaction carried out in the absence of solvent which has low reaction rate and reduced yield (44.5% in 6 days of reaction). Both solvents enhanced the transesterification yields and reaction rates; however tert-butanol showed better performance at lower proportion (15%). Under this condition, yields in the order of 96% were attained in 96 hours, probably due to the moderate polarity and lower viscosity of this solvent which dilutes the glycerol accumulated in support and improved the substrate transfer into the interior of the immobilized cells by preventing the enzyme inhibition by limitation of the mass transfer. Overall, the results were promising and showed the potential of whole-cells from M. circinelloides URM 4182 immobilized in polyurethane to mediate the synthesis of biodiesel in a continuous packed bed reactor.
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Nikam, Shantanu P. "RATIONAL DESIGN AND SYNTHESIS OF FUNCTIONAL POLYMERS FOR ANTIMICROBIAL, ANTI-FOULING AND ANTI-ADHESIVE BIOMATERIAL APPLICATIONS." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1620215379000849.
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Nardi, Ivana Ribeiro De. "Degradação de benzeno, tolueno, etilbenzeno e xilenos (BTEX) em reator anaeróbio horizontal de leito fixo (RAHLF)." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-18122015-114648/.
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A atividade industrial diversificada tem sido responsável pelo lançamento, no ambiente, de resíduos que contém materiais tóxicos e/ou de difícil degradação. Benzeno, tolueno, etilbenzeno e xilenos (BTEX) são compostos importantes, por estarem presentes em águas superficiais e subterrâneas, geralmente a partir de contaminações por derivadas de petróleo. Enquanto a degradação aeróbia de BTEX já está amplamente entendida e descrita, a aplicação de processos anaeróbios de tratamento, indicados na década de 80 ainda requer mais estudos. Reatores anaeróbios horizontais de leito fixo de bancada preenchidos com cubos de espuma de poliuretano, contendo lodo anaeróbio proveniente de diversas fontes trataram a água residuária sintética a base de proteínas, carboidratos, lipídios, contendo solução etanólica de BTEX e solução de BTEX em detergente comercial; e solução etanólica de BTEX como únicas fontes de carbono. A influência da adição de nitrato e sulfato como aceptores de elétrons na degradação anaeróbia também é discutida. Os reatores foram capazes de remover BTEX nas concentrações testadas de até 15,0 mg/L de cada composto, com tempos de detenção hidráulica de 11,4 horas e 13,5 horas. Os reatores forneceram condições excelentes para o desenvolvimento de biofilme complexo capaz de degradar BTEX, contendo organismos degradadores de BTEX, acetogênicos, acetoclásticos e hidrogenotróficos. Arqueas metanogênicas representaram menos de 0,5% do total de organismos anaeróbios na biomassa dos reatores. O modelo cinético de primeira ordem com residual foi o que melhor representou os dados experimentais e as velocidades de degradações de BTEX, estimadas neste trabalho, foram cerca de 10 a 94 vezes maiores que as encontradas na literatura, em ensaios realizados em microcosmos.The diversified industrial activity has been responsible for discharge in the environment of toxic and/or difficult degradation compounds. Benzene, toluene, ethylbenzene and xylenes (BTEX) are important compounds present in surface and ground waters, usually from petroleum products contamination. While BTEX aerobic degradation is extensively understood and described, anaerobic treatment application, started in the eighties, associated to fundamental studies need to be improved. Bench-scale horizontal-flow anaerobic immobilized biomass reactors filled with polyurethane foam matrices, containing immobilized anaerobic biomass from various sources, treated synthetic substrate containing protein, carbohydrates, lipids, BTEX solution in ethanol and BTEX solution in commercial detergent, as well as BTEX solution in ethanol as the sole carbon source. The influence of the addition of nitrate and sulfate as electron acceptors on anaerobic degradation is also discussed. The reactors were able to remove up to 15.0 mg/L of each BTEX compound, with hydraulic detention time of 11.4 hours and 13.5 hours. The reactors provided excellent conditions for developing a complex biofilm with BTEX-degraders, acetogenic, acetoclastic and hydrogenotrophic microorganisms. Methanogenic archaea were found to represent less than 0.5% of the total anaerobic organisms in the biomass inside the reactors. Residual first order kinetic model fitted well the experimental data and the BTEX degradation rates, estimated in this work, were about 10- to 94-fold higher than those found in the literature, in microcosms studies.
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Wendling, Ana Cláudia. "Remoção simultânea de matéria organica e nitrogênio total em reator de leito estruturado com aeração intermitente tratando efluente composto por esgoto bruto e efluente de ralf." Universidade Estadual de Ponta Grossa, 2017. http://tede2.uepg.br/jspui/handle/prefix/2424.
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O consumo do oxigênio dissolvido nos corpos hídricos é um dos principais problemas resultantes da poluição nas águas por matéria orgânica. Outro ponto importante é a eutrofização, que é o crescimento excessivo das plantas devido ao excesso de nutrientes presentes nesse meio. As estações de tratamento de esgoto brasileiras costumam utilizar processos biológicos para a remoção da matéria orgânica e do nitrogênio. Nesse sentido visando a remoção simultânea da Demanda Química de Oxigênio (DQO) e de Nitrogênio Total (NT) do esgoto sanitário, o presente estudo teve como objetivo avaliar a eficiência de um reator de leito estruturado com aeração intermitente, com períodos de aeração de 60 minutos seguidos de 120 minutos sem aeração, a cada ciclo de 180 minutos. O reator foi operado com Tempo de Detenção Hidráulica (TDH) de 8 horas, temperatura de 30 ± 1ºC, alimentação contínua e razão de recirculação igual a 2. Foram realizados 5 ensaios que se diferenciaram em a composição do afluente. Os afluentes foram compostos por uma combinação de parcelas de esgoto sanitário bruto da Estação de Tratamento de Esgoto (ETE) Verde e efluente de Reator Anaeróbio de Leito Fluidizado (RALF) da mesma ETE. As concentrações de cada parcela no afluente foram de 0%, 25%, 50%, 75% e 100%. Como meio suporte para a fixação dos microrganismos foram utilizados 13 cilindros de espuma de poliuretano dispostos verticalmente no reator. Para avaliação da eficiência do processo, foram realizadas as análises de pH, alcalinidade, Nitrogênio Total Kjeldahl (NTK), nitrogênio amoniacal (N-NH4+), nitrito (N-NO2-), nitrato (N-NO3-), Demanda Química de Oxigênio (DQO) e fósforo. A eficiência mínima de remoção de DQO obtida foi de 76% e a máxima de 95%, porém os resultados apontaram que não houve diferença estatística significativa entre os ensaios para esse parâmetro. A melhor eficiência de remoção de NT foi de 78%, com afluente composto apenas por efluente do RALF, que foi o ensaio 3. Nestas condições o efluente apresentou teores de DQO de 14 mg.L-1, de N-NH4+ de 3 mg.L-1, de N-NO3- de 2 mg.L-1 e de N-NO2- de 3 mg.L-1. Diante dos resultados foi possível concluir que o reator de leito estruturado e aeração intermitente é eficiente para a remoção simultânea da matéria orgânica carbonácea e nitrogenada com afluente contendo uma mistura do esgoto bruto e efluente de RALF nas mais diferentes proporções.
The consumption of dissolved oxygen in water bodies is one of the main problems resulting from water pollution by organic matter. Another important point is eutrophication, which is the excessive growth of plants due to the excess of nutrients present in this medium. Brazilian sewage treatment plants usually use biological processes for the removal of organic matter and nitrogen. In this sense, aiming at the simultaneous removal of Chemical Oxygen Demand (COD) and Total Nitrogen (TN) from sanitary sewage, the present study aimed to evaluate the efficiency of a structured bed reactor with intermittent aeration, with aeration periods of 60 Minutes followed by 120 minutes without aeration, with each cycle of 180 minutes. The reactor was operated with Hydraulic Detention Time (HDT) of 8 hours, temperature of 30 ± 1ºC, continuous feed and recirculation ratio equal to 2. Five trials were performed that differed in the composition of the influent. The influente were composed of a combination of raw sewage plots from the Green Sewage Treatment Station (ETE) and the Fluidized Bed Anaerobic Reactor (RALF) effluent from the same ETE. The concentrations of each plot in the affluent were 0%, 25%, 50%, 75% and 100%. As a support medium for Microorganisms were used 13 polyurethane foam cylinders arranged vertically in the reactor. In order to evaluate the efficiency of the process, pH, alkalinity, Total Kjeldahl Nitrogen (TKN), ammoniacal nitrogen (N-NH4+), nitrite (N-NO2-), nitrate (N-NO3-), Chemical Demand Oxygen (COD) and phosphorus. The minimum COD removal efficiency obtained was 76% and the maximum of 95%, but the results showed that there was no significant statistical difference between the tests for this parameter. The best effluent removal efficiency was 78%, with an effluent composed only of RALF effluent, which was test 3. Under these conditions, the effluent had COD contents of 14 mg.L-1, 3 mg N-NH4+.L-1, N-NO3- of 2 mg.L-1 and N NO2- of 3 mg.L-1. In view of the results it was possible to conclude that the structured bed reactor and intermittent aeration is efficient for the simultaneous removal of carbonaceous and nitrogenous organic matter with a influent containing a mixture of crude sewage and RALF effluent in the most different proportions.
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Oliveira, Lorena Lima de. "Influência do material suporte na degradação de alquilbenzeno linear sulfonado (LAS) em reator anaeróbio." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-17082006-161823/.
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Neste trabalho foi estudada a degradação anaeróbia do alquilbenzeno linear sulfonado (LAS), um surfactante largamente utilizado na fabricação de detergentes e presente em águas residuárias domésticas e industriais. Para isso, foram utilizados dois reatores anaeróbios horizontais de leito fixo (RAHLF) preenchidos com diferentes materiais suporte para imobilização da biomassa: carvão vegetal (RAHLF1) e leito misto de argila expandida e espuma de poliuretano (RAHLF2). O inóculo usado foi lodo proveniente de reator anaeróbio de fluxo ascendente e manta de lodo (UASB) utilizado no tratamento de águas residuárias de suinocultura. Os reatores foram alimentados, numa primeira etapa, com esgoto sintético e, posteriormente, suplementados com 14 mg/L de LAS. O tempo de detenção hidráulica (TDH) utilizado foi de 12 horas. Foi possível constatar que a presença do surfactante na alimentação não afetou a remoção de matéria orgânica (DQO), próxima a 90% em ambos os reatores para afluente com DQO de 550 mg/L. Com o balanço de massa constatou-se que os reatores foram aptos a remover LAS em 30% no RAHLF1 e 35% no RAHLF2. Desse total, 28% e 27%, respectivamente, foram degradados biologicamente, após 343 dias de operação. O restante manteve-se adsorvido nos materiais suportes. O pH no efluente dos RAHLFs manteve-se constante e próximo a 7,0. Alcalinidade foi gerada, assim como ácidos voláteis, apresentando concentrações médias de 342 e 353 mgCaCO3/L e 27 e 24 mgHAc/L no RAHLF1 e RAHLF2, respectivamente, durante operação com 14 mg/L de LAS no afluente. Ácidos acético e propiônico foram observados nos reatores em concentrações de até 50 e 12 mg/L, respectivamente. Em ambos os reatores estiveram presentes microrganismos com morfologias semelhantes a Methanosarcina sp., Methanosaeta sp., bacilos, cocos e filamentos, entre outros. Utilizando-se técnicas de Biologia Molecular (PCR/DGGE) verificou-se, em ambos os reatores, ampla variedade populacional de microrganismos pertencentes aos Domínios Bacteria, Archaea e ao Grupo BRS. Os materiais suportes selecionaram o crescimento de diferentes populações microbianas. No entanto, para o RAHLF2, praticamente não ocorreu estratificação populacional para os dois suportes. No RAHLF1, algumas populações foram semelhantes às observadas no reator de leito misto e outras cresceram mais favoravelmenteThe aim of this work was to study the anaerobic degradation of LAS (linear alquilbenzene sulphonate), which is a surfactant widely used in manufacture of detergents and commonly found in domestic and industrial wastewaters. For the experimental purpose it was used two horizontal anaerobic immobilized biomass (HAIB) reactors filled with different support materials for biomass immobilization, such as: vegetal coal (HAIB1) and a mix of expanded clay and polyurethane foam (HAIB2). The biological material used as inoculum was obtained with the sludge of an upflow anaerobic sludge blanket reactor (UASB) treating suine wastewater. The reactors were fed, in a first stage, with synthetic sewage and, in a second, with a synthetic sewage supplemented with 14 mg/L of LAS. The applied hydraulic detention time was of 12 hours. With the chemical routine analyses it was possible to ascertain the evidence that the presence of surfactant in the feeding influent did not affect organic matter removal efficiencies (COD), which were close to 90% for both reactors treating 550 mg/L COD. The mass balance results suggested that the reactors removal efficiency of LAS were of 30% in RAHLF1 and 35% in RAHLF2. Of the total concentration of used LAS in the experiments, 28% and 27% were degraded biologically after 343 days of operating regime. The remaining LAS concentrations were adsorbed on the support materials. The pH values in the systems remained unaltered and close to 7.0. Alkalinity was generated (342 and 353 mgCaCO3/L, respectively), and volatile acids were recorded at concentrations of 24 and 27 mgHAc/L in RAHLF1 and RAHLF2, respectively, both treating effluent containing 14 mg/L of LAS. Acetic and propionic acids were detected in the reactors at concentrations up to 50 and 12 mg/L, for reactors 1 and 2, respectively. In both reactors it was observed microorganisms with morphologies resembling Methanosarcina sp., Methanosaeta sp., rods, cocus, filaments and others. Techniques of Molecular Biology (PCR/DGGE) showed high diversity of Bacteria, Archaea and BRS Group in both reactors. The support material selected different microbial populations. For RAHLF2, however, microbial stratification when using the distinct support material was not observed. In RAHLF1, it was observed that some populations were similar within the reactor of mixing bed where others grew more favorably
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Róz, Alessandra Luzia da. "Preparação e caracterização de amidos termoplásticos." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-11062008-150517/.
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Este trabalho teve como objetivo estudar o processo de plasticização do amido via mistura física e por reação química para a produção de novos materiais. A plasticização via mistura física foi realizada empregando-se como agentes plasticização diferentes compostos hidroxilados. Os amidos termoplásticos (TPS) foram processadas em misturador intensivo a 150°C, a partir de misturas contendo de 15 a 40% de agente plasticizante. A plasticização via reação química foi realizada com isocianatos monofuncionais e difuncionais, os quais levaram a obtenção de produtos de enxertia e entrecruzamento, respectivamente. Os produtos obtidos foram caracterizados por difração de Raios X, Calorimetria Exploratória Diferencial (DSC), Termogravimetria (TG), Análise Dinâmico-Mecânica (DMA), Microscopia Eletrônica de Varredura (SEM) e Cromatografia de Permeação em Gel (HPSEC). O estudo dos diferentes plasticizantes propiciou a determinação das características que estas substâncias devem possuir para a preparação de amidos termoplásticos. O cisalhamento desenvolvido durante o processamento em misturador intensivo levou à perda da estrutura cristalina e à desestruturação dos grânulos de amido. O processamento do TPS em misturador intensivo não provoca mudanças significativas na massa molar do amido termoplasticizado. Os amidos termoplasticizados com sorbitol foram aqueles que apresentaram menores valores de absorção de água. Os valores de módulo de Young das amostras plasticizadas com propilenoglicol aumentaram com o aumento do conteúdo de plasticizante. Para as amostras plasticizadas com etilenoglicol o módulo aumenta até 30% de conteúdo de plasticizante, quando ocorre uma diminuição do valor do módulo. Os TPS plasticizados com propilenoglicol, 1, 4-butanodiol, sorbitol e dietilenoglicol apresentaram um aumento da temperatura de transição vítrea com o aumento do tero de plasticizante. Os diferentes TPS obtidos via mistura física apresentaram estabilidade térmica similares à exibida pelo amido in natura. As propriedades mecânicas destes materiais variaram de acordo com o tipo e a quantidade de plasticizante empregado. A análise dos produtos obtidos via reação química (amidos enxertados e entrecruzados) revelou que estas reações promoveram a desestruturação dos grânulos de amido e, independentemente do regente empregado, a modificação produziu derivados mais hidrofóbicos que o amido in natura. A reação do amido com o oligômero de poli-óxido de propileno tolueno di-isocianato permitiu a obtenção de um derivado com propriedades de material elastomérico e elevada capacidade de intumescimento. Os derivados enxertados ou entrecruzados apresentaram perda de cristalinidade, redução do caráter hidrofílico e estabilidades térmicas semelhantes à apresentada pelo amido in natura.This main of this work was to study of the cornstarch granules plasticization by means of physical or chemical treatments in order to prepare new materials. The plasticization by physical processing was performed in an intensive mixer at 150°C using ditferent hydroxylated compounds as plasticizers. The production of thermoplastic starch (TPS) by chemical reaction was carried out using mono and di-isocyanates to obtain grafted and cross linked derivatives, respectively. All the products were characterized by X Ray Diffraction, Ditferential Scanning Calorimetry (DSC), Thermogravimetry (TG), Dynamical Mechanical Analysis (DMA), Scanning Electron Microscopy (SEM), High Pressure Size Exclusion Chromatography (HPSEC). The utilization of ditferent plasticizer permitted determining which characteristics the substances must present to be used in the TPS preparation. The shear developed in the processing step lead to the loss of crystalline pattern and disruption of the starch granules. The utilization of intensive mixer does not produce significant changes in the molar mass of the thermoplastic starch. TPS produced using sorbitol as plasticizer presented the lowest level of water uptake. The valous of Young modulus for TPS produced with propylene glycol increased with the content of plasticizer. To samples produced with ethylene glycol the values of Young modulus increased until 30% and after the modulus decrease. TPS prepared with propylene glycol, 1, 4-butanediol, sorbitol and diethyleneglycol showed an increase in the glass transition temperature with the increase in the plasticizer content. The ditferent TPS produced by physical mixture shoed thermal stabilities similar to the one exhibited by in natura starch. The mechanical properties of these materials were dependent of the type and amount of plasticizer. The analysis of the derivatives obtained by chemical reaction (grafted and cross linked) revealed the occurrence of disruption of the starch granules and, independent1y of isocyanate, the products presented higher hydrophobic character than that one presented by in natura starch. By reaction starch with propylene toluene polyoxide oligomer, it was obtained a derivative with elastomeric properties and high swelling capability. The grafted or cross linked derivatives showed loss of crystallinity, decrease in hydrophilic character, and thermal stability similar to the one exhibited by in natura starch.
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Bendaikha, Tahar. "Photopolymérisation réticulante de macromères multifonctionnels : comportement photochimique de réseaux polyacryliques tridimensionnels." Mulhouse, 1986. http://www.theses.fr/1986MULH0016.
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Cinétique de la photopolymérisation des macromères multiacrylates, influence des constituants de la résine photosensible; influence de l'oxygène sur la photopolymérisation de résines multiacrylates; influence de l'intensité lumineuse; caractéristiques des réseaux polymères photoréticulés. Photodégradation des réseaux époxy-acrylates; photooxydation des polyuréthannes acrylates réticules
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Polak, Rafael. "REATOR DE LEITO EMPACOTADO EM ESCALA PILOTO PARA REMOÇÃO DE MATÉRIA ORGÂNICA E NITROGENADA DE ESGOTO SANITÁRIO." Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2708.
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Essa pesquisa teve por objetivo principal avaliar o desempenho de um reator em escala piloto de leito empacotado e fluxo contínuo sob diferentes condições operacionais de aeração, na remoção biológica de matéria carbonácea e nitrogenada, de efluente sanitário. O reator possuía um volume total de 5,65 m³ e volume útil de 4,75 m³, devido ao volume ocupado pelo material suporte. O meio suporte utilizado para fixação de microrganismos foi o dispositivo denominado Biobob®, que consiste em uma matriz de espuma de poliuretano envolta por uma estrutura de polipropileno, com geometria cilíndrica de 45 mm de diâmetro e 60 mm de altura. O reator foi operado com um Tempo de Detenção Hidráulica (TDH) de 12 horas, razão de recirculação de 2 vezes vazão de alimentação e foi alimentado continuamente por afluente composto por mistura de esgoto sanitário não tratado e efluente de Reator Anaeróbio de Leito Fluidizado (RALF) na proporção de 1:1 (v:v). Foram explorados três ciclos de operação de 180 minutos: (10) aerando continuamente por 180 minutos, (2) aerando 60 minutos e não aerando 120 minutos, e (3) aerando 120 minutos e não aerando 60 minutos. Os resultados mostraram não haver diferença estatística nas eficiências de reduções de Demanda Química Oxigênio (DQO) entre as três condições estudadas, com eficiências médias de 76,34%, 75,32% e 79,80%, respectivamente, indicando que o tempo de aeração não influenciou na eficiência de redução. A DQO efluente do reator variou entre 31 mg.L-1 e 206 mg.L-1. A eficiência de nitrificação se mostrou fator limitante na remoção de NT. As condições (1) e (3) com maiores taxas de nitrificação, 75% e 70% respectivamente, obtiveram as melhores eficiências de remoção de NT, com taxas de 65% em ambas. A relação DQO/NTK durante as 3 etapas da pesquisa foi próxima a 9,59. A condição (3) apresentou diferença estatística significativa na remoção de NT devido a maior disponibilidade de doadores de elétrons, com relação DQO/NTK de 11,2. A desnitrificação apresentou médias de remoções de 87%, 89% e 94%, nas condições 1, 2 e 3, respectivamente. Pelos resultados obtidos, pode-se concluir que o reator piloto de leito empacotado e aeração intermitente foi eficiente na remoção simultânea de matéria orgânica e nitrogenada, podendo ser considerado uma alternativa interessante a ser utilizada no tratamento combinado de efluente de UASB e esgoto bruto.
The main objective of this research was to evaluate the performance of a pilot scale reactor of packed bed and continuous flow, on different aeration operating conditions, in the biological removal of carbonaceous and nitrogenous matter from sanitary effluent. The reactor has a total volume of 5.65 m³, and a useful volume of 4.75 m³ due to the volume occupied by the structured bed. The medium used to fix microorganisms was the device called Biobob®, which consists of a polyurethane foam matrix enveloped by a polypropylene structure, with a cylindrical geometry of 45 mm in diameter and 60 mm in height. The reactor was operated with a 12 hour Hydraulic Retention Time (HRT), recirculation rate of 2 times feed rate and was continuously fed by a mixture of untreated sewage and effluent from an Upflow Anaerobic Sludge Blanket (UASB) in the proportion of 1:1 (v:v). Three 180-minute cycles of operation were performed: (1) continuous aeration for 180 minutes, (2) aeration 60 minutes and no aeration for 120 minutes and (3) aeration for 120 minutes and no aeration for 60 minutes. The results showed that there was no statistical difference in the efficiency of Chemical Oxygen Demand (COD) reductions between the three conditions studied, with mean efficiencies of 76.34%, 75.32% and 79.80%, respectively, indicating that the aeration did not influence the reduction efficiency. The COD concentrations effluent from the reactor varied between 31 mg.L-1 and 206 mg.L-1. The efficiency of nitrification was shown to be a limiting factor in NT removal. The conditions (1) and (3) with higher nitrification rates, 75% and 70%, respectively, obtained the best NT removal efficiencies, with rates of 65% in both. The COD / NTK ratio presented a high average during the 3 stages of the research, with an observed value of 9.59. Denitrification showed mean removals of 87% (1), 89% (2) and 94% (3). Condition (3) presented a statistically significant difference with the others due to the greater availability of electron donors, with a COD/NTK ratio of 11.2. From the results, we can conclude that the packed bed reactor and intermittent aeration is efficient in the simultaneous removal of organic matter and nitrogen and is an interesting alternative to be used in the treatment and post treatment of anaerobic reactors.
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Sarti, Arnaldo. "Desempenho de reatores anaeróbios operados em bateladas sequenciais em escala piloto no tratamento de esgoto sanitário." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-29072016-110026/.
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Este trabalho apresenta e discute os resultados obtidos na operação de quatro reatores anaeróbios operados em bateladas seqüenciais, projetados em escala piloto, para tratamento de 7,8 m3.dia-1 de esgotos sanitários, coletados da rede coletora que atravessa o Campus da USP de São Carlos. Cada sistema (1,2 m3) foi concebido para tratamento de 1,95 m3.dia-1 de esgoto sanitário, com concepções geométricas (relação L-altura/D-diâmetro), mecânicas (agitação mecânica ou recirculação de líquido) e tipo de retenção de biomassa diferentes. Três unidades eram do tipo ASBR (anaerobic sequencing batch reactor) e outro tipo ASBBR (anaerobic sequencing batch biofilm reactor) com leito fixo composto de matrizes cúbicas de espuma de poliuretano. Os ciclos operacionais tinham duração de oito horas perfazendo no total três ciclos por dia em cada sistema. O monitoramento dos reatores incluiu a determinação de DQO, pH, sólidos em suspensão totais (SST) e voláteis, ácidos voláteis totais, alcalinidade no afluente e efluente, bem como a concentração de metano no biogás. O ensaio experimental foi dividido em duas etapas distintas, sendo que na primeira (227 dias), os reatores não receberam inóculo e na segunda (66 dias) houve a inoculação prévia de lodo anaeróbio granular. Em ambas etapas, os dois reatores ASBR com mesmo tipo de agitação por recirculação de líquido, mas com diferente relação L/D não apresentaram desempenho satisfatório. Os valores médios de eficiência de remoção de DQO e de SST foram próximos de 40% e 60%, respectivamente. No efluente a concentração média foi de 300 mgDQO/L e de 100 mgSST/L. Nos reatores, ASBR com agitação mecânica e, ASBBR com biomassa imobilizada, os resultados médios obtidos foram melhores. O reator ASBBR atingiu eficiência média de 65% e 75% em remoção de DQO e SST, enquanto no ASBR com agitação mecânica chegou-se a 60% e 85%, respectivamente. A concentração média no efluente dos reator foi de 150 mgDQO/L e 60 mgSST/L no ASBBR e 220 mgDQO/L e 50 mgSST/L no ASBR com agitação mecânica.This study reports and discuss several data obtained using four pilot scale anaerobic sequencing batch reactor, treating 7.8 m3.d-1 of domestic sewage from the Sao Paulo University sewer treatment system (Campus- São Carlos). Each reactor system (1.2 m3) was designed for the treatment of 1.95 m3.d-1 of domestic sewage with different geometric reactor characteristics (ratio L-length/D-diameter), mechanical (mechanical mixing or liquor re-circulation) and biomass retention type. Three reactors were a conventional ASBR (anaerobic sequencing batch reactor) with granular biomass and another one, an anaerobic sequencing batch biofilm reactor (ASBBR), which was composed with cubic matrices of polyurethane foam. The reactors were operated within 8-h of a sequential batch cycle, which were attained in three cycles by day for each system. Chemical oxygen demand (COD), pH, total suspended solids (TSS), volatile fatty acids, bicarbonate alkalinity in both the influent and effluent were monitored in the different cycles. Methane concentration was also assessed in the same period using Gas Chromatography (GC). The experiments were divided in two different phases. In the first phase, which corresponded to 227 d, the reactors were not inoculated. In the second phase (66 d) the reactors were then inoculated with anaerobic granular sludge. It was observed that in both operational phases, the two ASBR reactors, with the same re-circulating process of the mixed liquor, but with different L/D ratio, showed non-satisfactory results. The average values of COD and TSS removal were close to 40 and 60%, respectively. In the effluent, the average values were of 300 mgDQO/L and 100 mgTSS/L. ASBR reactors with mechanical mixing and ASBBR reactor with immobilized biomass showed better results. The average removal efficiency observed was of 65 and 75% for COD and TSS, respectively. ASBR reactors with mechanical mixing reached the efficiency of 60 and 85% for COD and TSS removal. The average concentration in the effluent was of 150 mgDQO/L and 60 mgSST/l in the ASBBR reactor; and 220 mgCOD/L and 50 mgTSS/L in the ASBR reactor with mechanical mixing.
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Abreu, Sergio Brasil. "Estudo do desempenho de reator anaeróbio-aeróbio de escoamento ascendente no tratamento de esgoto sanitário com espuma de poliuretano como suporte de imobilização da biomassa." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-21032016-150822/.
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O projeto consistiu na concepção e avaliação do desempenho de um sistema anaeróbio-aeróbio para tratamento de esgoto sanitário. O leito do reator foi dividido em quatro compartimentos de igual volume. Foi usada espuma de poliuretano para imobilização da biomassa e, para facilitar a partida do reator, esse material suporte foi previamente inoculado. O projeto teve três fases distintas: na primeira etapa, foi observada a importância da concentração de biomassa anaeróbia no desempenho de reator anaeróbio a princípio operado com metade do leito reacional com espuma e, a seguir, com o leito todo preenchido com espuma. Na segunda etapa, foram testados diferentes tempos de detenção hidráulica no reator que operou apenas em condições anaeróbias. Na última etapa foi operado o reator combinado anaeróbio-aeróbio. Ficou constatada a importância da concentração de microrganismos no desempenho do reator anaeróbio, pois com o aumento da quantidade de espuma, o reator atingiu resultados melhores e maior estabilidade operacional. Foi comprovada a influência do tempo de detenção hidráulica (TDH) no desempenho do reator. Tempos de detenção muito altos acarretam problemas de transferência de massa líquido-sólido, e baixos TDH dificultam adequada ação dos microrganismos. O melhor resultado para o reator em operação exclusivamente anaeróbia foi para o TDH de 10 horas, no qual se conseguiu reduzir a DQO de amostra bruta de 389 +/- 70 mg/L para 137 +/- 16 mg/L, em média. Para o reator operado anaeróbio-aeróbio a DQO de amostra bruta decresceu de 259 +/- 69 mg/L para 93 +/- 31 mg/L, em média. A comparação de todos os resultados obtidos, evidenciou a importância do pós-tratamento aeróbio na remoção de parcela de matéria orgânica não removida em tratamento unicamente anaeróbio.The project consisted in the design and performance evaluation of an anaerobic-aerobic system for wastewater treatment. Polyurethane foam was used for biomass immobilization and, to smooth the reactor start-up, this supporting material was previously inoculated. The project was divided in three distinct phases. In the first one, the importance of the anaerobic biomass concentration was observed in the performance of the anaerobic reactor in a way to operate the reactor primarily with half of the reaction bed filled with foam and subsequently operate it with the bed completely filled with foam. In the second phase, different times of hydraulic retention were tested with the reactor operating exclusively in anerobic conditions. In the third and last phase, an anaerobic-aerobic combined reactor was operated. It was possible to confirm the importance of microorganism concentration in the performance of the anaerobic reactor, since the increase in the amount of foam allowed the reactor to reach better results and greater operational stability. The influence of the hydraulic retention time in the reactor performance was also proved. Very high retention times cause problems in the liquid-solid mass transference, while low retention times do not allow an adequate action of microorganisms. The best result for the reactor with an exclusive anaerobic operation was the 10 hour retention time, when it was possible to reduce the COD of a 389 +/- 70 mg/L gross sample to a 137 +/- 16 mg/L in average. On the other hand, for the anaerobic-aerobic operating reactor, the COD of a gross sample dropped from 259 +/- 69 mg/ L to 93 +/- 31 mg/L in average. Finally, comparing all the obtained results, it was possible to verify the importance of the anaerobic post treatment in the removal of a part of the organic matter not removed in an exclusively anaerobic treatment.
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Siman, Renato Ribeiro. "Reator anaeróbio em batelada seqüencial contendo biomassa imobilizada submetido a aumento de carga orgânica tratando água residuária sintética." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-30062016-142655/.
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Nesse estudo, procurou-se investigar a influência do aumento de carga orgânica em um ASBR operado a 30ºC, agitado mecanicamente e contendo microrganismos imobilizados em suporte inerte. Para tal, foi aplicado um carregamento orgânico volumétrico variando de 1,5 a 6,0 g DQO/L.dia, alimentando-se um reator construído em acrílico (5,4 L) com 2 L de água residuária sintética com concentrações de 500 a 2000 mg DQO/L com fontes de carboidrato/proteína/lipídio, em bateladas de 8 a 12 h. O sistema apresentou eficiências de remoção de material orgânico entre 73% e 88% para as condições estudadas. Entretanto, quando o reator foi alimentado com uma concentração de 2000 mg DQO/L em bateladas de 8 h, verificou-se o acúmulo de ácidos voláteis totais, refletindo na redução da eficiência de remoção de material orgânico para 55%, para amostras filtradas. Os perfis dinâmicos ao longo da batelada permitiram concluir que, para a condição com o mesmo carregamento orgânico, porém com concentrações afluentes e tempos de ciclo diferentes, a produção inicial de ácidos voláteis totais foi mais acentuada para o caso de alimentação com maior concentração. Para condições com concentrações afluentes iguais, o tempo a mais para o ciclo foi fundamental para obter-se efluente de melhor qualidade em termos de remoção de matéria orgânica.The current study investigated the effect of increasing organic load in an ASBR operated at 30ºC with mechanical stirring and containing immobilized on inert support. Accordingly, volumetric organic loading rates ranging from 1.5 to 6.0 g COD/L.day were used by feeding an acrylic reactor (5.4 L) with 2 L of influent at concentrations of 500 to 2000 mg COD/L from wastewater containing carbohydrates, proteins and lipids in 8 and 12 h batches. Organic matter removal efficiencies between 73% and 88% were observed under the conditions investigated. However, when the reactor was fed at a concentration of 2000 mg COD/L in 8 h batches, accumulation of total volatile acids was detected, leading to a reduction in organic matter removal efficiency as low as 55% for filtered samples. The dynamic batches profiles allowed to conclude that for the same organic loading rates and different concentration influent and cycle times, the initial production of total volatile acids showed to be more pronounced for better quality effluent in terms of organic matter removal.
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Nocko, Lissa Maria. "Remoção de carbono e nitrogênio em reator de leito móvel submetido à aeração intermitente." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-11022009-173925/.
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O lançamento de águas residuárias contendo compostos nitrogenados tem um importante impacto sobre a saúde e o meio ambiente, tornando necessária a incorporação de processos de remoção desses compostos nos sistemas de tratamento de águas residuárias. Neste trabalho, foram estudadas as condições de operação para promover a remoção conjunta de nitrogênio e matéria orgânica em reator biológico de leito móvel, contínuo, operado sob aeração intermitente, alimentado com água residuária sintética contendo nitrogênio amoniacal (90 a 110 mg/L) e melaço como matéria orgânica (DQO de 450 a 550 mg/L). Foram utilizados dois reatores em escala de bancada, cada um com dois litros de volume útil, contendo diferentes meios suportes para a imobilização da biomassa: matrizes de espuma de poliuretano e anéis plásticos. Na primeira etapa experimental, o reator contendo anéis plásticos apresentou eficiências de remoção de nitrogênio muito baixas. Na segunda etapa, trocou-se o material suporte por matrizes de espuma de poliuretano inoculadas com lodo aeróbio de estação de tratamento de águas residuárias. A partir de então, trabalhou-se com dois reatores de mesma configuração, exceto pelas origens, idades e características dos lodos de inóculo. Inicialmente, a alimentação foi realizada utilizando-se apenas os micronutrientes contidos no melaço. Posteriormente, a composição da água residuária foi alterada, introduzindo-se solução de micronutrientes, pois se concluiu que a instabilidade no processo de nitrificação devia-se ao fato de o melaço comercial apresentar deficiências nutricionais. Como resultado, em condições de estabilidade operacional, foram obtidas eficiências de remoção de DQO superiores a 85%, oxidação total do nitrogênio amoniacal e eficiências de remoção de nitrogênio de aproximadamente 55%. Variações posteriores nas condições de operação, como o aumento do período anóxico (de 1h para 1h15min) e redução do tempo de detenção hidráulica (para valores inferiores a 12 horas), resultaram em melhora no desempenho dos reatores. Os resultados obtidos permitem admitir que as melhores condições de operação não foram atingidas durante o experimento, abrindo a possibilidade para a otimização do processo em pesquisas futuras. Constatou-se que o desenvolvimento das populações microbianas imobilizadas no meio suporte foi diferente do observado na biomassa em suspensão. Verificou-se, também, que a biomassa responsável pela nitrificação e desnitrificação ocorreu predominantemente no meio suporte, enquanto que a biomassa heterotrófica predominou no lodo em suspensão.The operating conditions for the combined removal of nitrogen and organic matter in moving- bed biological reactor were investigated. Two bench-scale reactors, two liters each, were operated under intermittent aeration and continuously fed with synthetic wastewater containing ammonia nitrogen (90 to 110 mg/L) and molasses as organic carbon source (COD of 450 to 550 mg/L). Each reactor received different moving-bed materials: polyurethane foam matrices and plastic rings, respectively. During the first experimental period, the reactor containing plastic rings maintained very low nitrogen removal efficiencies during large period. For this reason, the moving-bed was replaced by polyurethane foam matrices and the reactor was re-inoculated with aerobic wastewater plant sludge. Thereafter, the two reactors were similar except for the origin, age and characteristics of the inoculum sludge. First, the wastewater micronutrients were just those contained in the carbon source (molasses). After, the synthetic wastewater composition was changed by adding a solution of micronutrients. This procedure was adopted to achieve a stable nitrification process, because commercial molasses is a very poor regarding its micronutrient composition. As a result of the stable conditions prevalence just after adding micronutrients, organic matter (as COD) removal efficiencies were higher than 85% and complete nitrogen ammonia oxidation was achieved. In nitrogen removal efficiencies were approximately 55%. The performance of the reactors improved after the increase of the anoxic period from1h to 1h15min, and reduction of the hydraulic detention time to less than 12 h. The results obtained in the last operating period indicated the optimum operating conditions was not achieved in this experiment, thus opening the possibility of process improvement in further researches. Microbial populations with different characteristics were developed in suspended growth and attached biomass. Nitrification and denitrification bacteria predominated as attached biomass whereas heterotrophic bacteria predominated as suspended growth biomass.
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Miqueleto, Ana Paula. "Comportamento de reator anaeróbio operado em batelada seqüencial, contendo biomassa imobilizada e submetido a aumento progressivo da concentração de substrato de fácil degradação." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-02072009-085827/.
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Os objetivos deste trabalho foram avaliar o desempenho do reator anaeróbio operado em batelada seqüencial quando submetido ao aumento progressivo da concentração de glicose e estimar os parâmetros cinéticos da degradação da glicose. Inicialmente o reator foi operado com ciclos de 8 horas, tratando glicose nas concentrações, aproximadas, de 500, 1000 e 2000 mg/L. Não foi detectada glicose no efluente nas três condições. O reator operou de maneira estável, tratando aproximadamente 500 mg/L de glicose, com eficiência na remoção da DQO filtrada entre 93% e 97%. Na operação com concentrações de glicose no afluente próximas de 1000 mg/L e 2000 mg/L, observou-se instabilidade operacional, principalmente devido à produção de polímeros extracelulares (EPS) que comprometeram a hidrodinâmica e a transferência de massa no sistema. Os valores médios da concentrações de ácidos voláteis no efluente foram de 159 ± 72 mg/L e 374 ± 92 mg/L, respectivamente. Aos perfis de concentração de glicose foi ajustado modelo de primeira ordem, enquanto que um modelo modificado, contemplando concentração residual de matéria orgânica, foi ajustado aos perfis temporais de DQO. Para verificar a formação do EPS, operou-se o reator com 3 horas de ciclo nas concentrações, aproximadas, de 500 e 1000 mg/L. Esta fase teve como objetivo verificar a hipótese, segundo a qual, a produção de EPS seria resultado da exposição da biomassa a baixas concentrações de matéria orgânica por longo período. Dessa forma, reduzindo o tempo de ciclo, a exposição a baixas concentrações também seria reduzida. No entanto, embora o reator tenha operado com relativa estabilidade, verificou-se formação de grande quantidade de EPS logo na primeira condição operacional, com aproximadamente, 500 mg/L de glicose no afluente, indicando que a hipótese não estava correta.The main objectives of this study were to evaluate the performance of the anaerobic sequencing batch reactor when subjected to a progressive increasing of the influent glucose concentration and estimate the kinetic parameters of glucoses degradation. Initially the reactor was operated with 8-hour cycles, treating glucose at concentrations of 500, 1000 and 2000 mg/L. Glucose was not detected in the effluent in all these three conditions. The reactor showed operating stability treating glucose concentration of approximately 500mg/L, with efficiencies between 93% to 97% in the filtrated COD removal. In the operation with glucose concentrations of 1000 mg/L and 2000 mg/L, approximately, it could be noticed an operational instability, caused mainly by a production of extracellular polymers (EPS) leading to hydrodynamic and mass transfer problems in the reactor. The mean values of volatile acids concentration in the effluent were about 159 ± 72mg/L and 374 ± 92mg/L, respectively. A first order model was adjusted to glucose concentration profiles, and a modified model, including a residual concentration of substrate, was adjusted to COD temporal profiles. To verify the EPS formation, the reactor was operated with 3-hour cycle in the concentrations of 500 and 1000 mg/L This stage had the objective of verifying if the EPS production would result from the exposure of the biomass to low concentration of substrate for a long period of time. Thus, reducing the time cycle, the exposure to low concentrations would also be reduced. Nevertheless, even with the reactor operating with relative stability, the hypotheses could not be verified due the formation of a large amounts of EPS right in the first operational condition with approximately to 500 mg/L of glucose in the influent, showing that the hypothesis was not right.
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Lapa, Katt Regina. "Avaliação da recirculação da fase líquida e do regime de alimentação no reator anaeróbio, em escala piloto, operado em bateladas seqüenciais contendo biomassa imobilizada (ASBBR), no tratamento de esgoto sanitário." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-24032007-232108/.
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Avaliou-se a influência da recirculação da fase líquida e do regime de alimentação em reator anaeróbio no tratamento de esgoto sanitário. Utilizou-se um reator anaeróbio operado em bateladas seqüenciais, contendo biomassa imobilizada (ASBBR), em escala piloto, com volume total de 1,2 \'M POT.3\' (\'fi\' 1,0 m e altura 1,53 m). O leito suporte para a imobilização da biomassa era constituído por matrizes cúbicas de espuma de poliuretano, com 5 cm de aresta, confinadas em cesto de aço inox 304, colocado no interior do reator. A influência da recirculação da fase líquida sobre o desempenho do ASBBR quanto à remoção de matéria orgânica e quanto ao arraste de sólidos foi avaliada submetendo-se o reator às velocidades ascensionais de 1,27; 3,82; 7,64 e 10,18 m/h resultantes das diferentes vazões de recirculação impostas. Contrariamente ao observado em pesquisas anteriores em reatores operados em escala de bancada e alimentados com água residuária sintética, não houve aumento significativo da eficiência do reator com o aumento da velocidade ascensional no tratamento de esgoto sanitário. A influência do regime de alimentação de esgoto sanitário no desempenho do ASBBR foi avaliada submetendo-se o reator a tempos de enchimento correspondentes a 0,25 e 0,5 do tempo total de ciclo, utilizando-se a vazão de recirculação de 6 \'M POT.3\'/h, que foi a que apresentou os melhores resultados nos ensaios anteriores. Concluiu-se que o reator pode ser operado sob batelada alimentada com duração de até 0,5 tempo de ciclo, sem que seu desempenho seja significativamente alterado. Esse resultado é importante, pois representa que o sistema de tratamento composto por reatores ASBBR pode ser projetado com número menor de reatores. A fim de esclarecer dúvidas sobre o desempenho do ASBBR observado no tratamento de água residuária de composição complexa (esgoto sanitário), o reator foi alimentado com água residuária facilmente degradável (etanol). O desempenho do reator foi aquém do esperado, mesmo quando alimentado com composto de fácil degradação. Os ensaios de atividade metanogênica específica (AME) demonstraram que houve decréscimo dos valores de AME com o aumento da velocidade ascensional. Os valores obtidos foram 0,0632; 0,0509; 0,0248 e 0,0299 g DQO-CH4/(g STV.d), respectivamente, para os valores de Va de 1,27; 3,82; 7,64 e 10,19 m/h. Concluiu-se que a baixa eficiência de remoção de matéria orgânica deveu-se ao abaixamento progressivo da atividade metanogênica do lodo, cujas causas não puderam ser completamente esclarecidas nesta pesquisa.The influence of the liquid phase recirculation and the feeding regimen on the performance of an anaerobic sequencing batch reactor containing immobilized biomass (ASBBR) applied for the treatment of domestic sewage was evaluated. Biomass immobilization was provided by a basket containing cubic polyurethane foam matrices (5 cm side) inside the 1.2 \'M POT.3\' (1.0 m diameter and 1.53 m height) pilot-scale reactor. The influence of the liquid phase recirculation on the reactor performance in respect to organic matter and solids wash-out was verified by subjecting the reactor to a wide range of up flow velocities (1.27; 3.82; 7.64 and 10.18 m/h) resulting from different recirculation flow rates imposed. The increase of the up flow velocity did not increase the efficiency of the pilot reactor as expected. This result contradicts those obtained with bench-scale ASBBR experiments treating synthetic wastewaters. The influence of the feeding regimen was verified by subjecting the reactor to feeding times correspondent to 0.25 and 0.50 of the total cycle time, at the recirculation flow rate of 6 \'M POT.3\'/h. It could be concluded that the reactor can be operated at the feeding batch mode up to 0.5 of the cycle time. This result is important for full scale applications considering that a treatment system composed of ASBBR reactors can be designed using a lower number of units. In order to clear some aspects related to the limited performance of the ASBBR reactor treating a complex wastewater (sewage), the reactor was subjected to an easily degradable wastewater (ethanol). However, the performance was not improved even when the reactor was treating an easily degradable compound. The results from the specific methanogenic activity (SMA) demonstrated a decrease on the values of SMA with the increase of the up flow velocity. The values of SMA were 0.0632; 0.0509; 0.0248 and 0.0299 g DQO-CH4/(g STV.d) for the Va of 1.27; 3.82; 7.64 and 10.19 m/h respectively. It could be concluded that the low efficiency obtained for organic matter removal was due mainly to the progressive decrease of the sludge methanogenic activity. The causes for that behaviour could not be completely explained in this research. It could be concluded that the reactor performance was iv clearly limited by the low productivity of the methanogenic populations present in the biomass.
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Cai, Xiaoshuang. "Production of carbonated vegetable oils from a kinetic modeling to a structure-reactivity approach Structure-reactivity : comparison between the carbonation of epoxidized vegetable oils and the corresponding epoxidized fatty acid methyl ester Aminolysis of cyclic-carbonate vegetable oils as a non-isocyanate route for the synthesis of polyurethane: a kinetic and thermal study Influence of ring‐opening reactions on the kinetics of cottonseed oil epoxidation Investigation of the physicochemical properties for vegetable oils and their epoxidized and carbonated derivatives Influence of gas-liquid mass transfer on kinetic modeling : carbonation of epoxidized vegetable oils." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR05.
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La valorisation de la biomasse et du dioxyde de carbone est à présent considérée comme une solution aux problèmes environnementaux du réchauffement climatique et l'épuisement des réserves de pétrole. Ainsi, les huiles végétales ont attiré l'attention croissante des milieux universitaires et industriels, comme une source de biomasse potentielle renouvelable qui peut être appliquée à la production de substitut fossile pour un développement durable, due à leurs caractères renouvelables, durables, biodégradables. De plus, cette biomasse est disponible avec une énorme quantité. Durant des décennies de recherches, les processus d'époxydation et de carbonatation sont deux méthodes d'application populaires pour la valorisation des huiles végétales. La conversion des huiles végétales en huiles époxydées est définie par une conversion d'un composé insaturé en un groupe époxyde. Jusqu'ici, l'oxydation de Prileschajew est la méthode de synthèse plus efficace pour la possible industrialisation du processus d'époxydation de huiles végétales, qui est une manière conventionnelle bien connue à utiliser comme processus de production commerciale. Ce type d'époxydation utilise l'acide percarboxylique comme transporteur d'oxygène qui est formé in situ dans la phase aqueuse, et ensuite époxyde les groupes insaturés des huiles végétales en groupes époxyde. Cependant, cette méthode présente une réaction secondaire d'ouverture du cycle du groupe époxyde au cours du processus. Donc, les conditions du procédé d'époxydation doivent être optimisées afin de minimiser les réactions d'ouverture de cycle. Des paramètres de réaction, y compris la concentration en catalyseur acide (acide sulfurique), réactifs (eau, groupe époxyde, peroxyde d'hydrogène, acide acétique) et la température de réaction, ont été discutés dans cette étude pour l'époxydation et réaction d'ouverture de cycle des huiles végétales. Au cours de la modélisation cinétique, les constantes cinétiques associées pour les réactions d'ouverture du cycle ont été estimées. En se basant sur ce modèle, les réactions d'ouverture du cycle époxyde par les acides acétique et peracétique sont plus rapides que celles de l'eau et du peroxyde d'hydrogène. Un réacteur en mode semi-fermé, avec addition du peroxyde d'hydrogène et de l'acide sulfurique, est la configuration la plus appropriée pour la production d'huiles végétales époxydées. Pour déterminer les conditions optimales et passer à échelle industrielle dans les procédés d'époxydation et de la carbonation, il faut connaître différentes propriétés physicochimiques telles que la viscosité, la densité, l'indice de réfraction, la capacité thermique spécifique et les évolutions de ces données avec la température. Cependant, aucune information sur ces propriétés est disponible dans la littérature. Pour cette étude, l'évolution de ces propriétés ont été déterminées pour trois huiles végétales et leurs dérivés époxydées et carbonates (l'huile de coton, l'huile de lin et l'huile de soja) avec la température et leur composition. La densité et l'indice de réfraction ont été trouvé linéairement dépendant de la température pour les huiles étudiées. La relation entre la contrainte de cisaillement et le taux de cisaillement dans l’étude de viscosité, indique que ces huiles sont des fluides newtoniens. Il a été démontré que la capacité thermique spécifique suit une équation polynomiale du second ordre avec la température. Sur la base de ces résultats, il a été démontré que certaines corrélations pourraient être utilisées pour prédire les évolutions de ces propriétés physicochimiques à différentes compositions et températuresNowadays, biomass and carbon dioxide valorization are considered as a helpful solution to the environmental issues of global warming and the depletion of petroleum reserves. Thus, vegetable oils have attracted increasing attention of academic and industrial communities, as one of the potential renewable biomass that can be applied to the production of fossil substitute for sustainable development, owning to their advantages of renewable, sustainable, biodegradable, and universally available with huge feedstock. Among decades of researches, epoxidation and carbonation processes are two popular application methods for vegetable oil valorization. The conversion of vegetable oils into epoxidized ones is defined by a conversion of unsaturated compound into an epoxide group. So far, the potential application for the production of epoxidized oil in the industrial is the Prileschajew oxidation, which is a wellknown conventional way to be used as the commercial production process. This type of epoxidation uses percarboxylic acid as an oxygen carrier, which is formed in situ in the aqueous phase, and then epoxidize the unsaturated groups on the vegetable oils into epoxide groups. During the process, however, this method presents side reaction of ring-opening of the epoxide group. Therefore, the selective epoxidation process conditions need to be optimized in order to minimize the ring-opening reactions. In this study, process parameters including the concentration of acid catalyst (sulfuric acid), reactants (water, epoxide group, hydrogen peroxide, acetic acid) and the reaction temperature have been discussed for the epoxidation and ring opening of vegetable oils. During the kinetic modeling stage, the related kinetic constants for the ring opening reactions were estimated. Based on this model, the ring opening by acetic and peracetic acids was found to be faster than by water and hydrogen peroxide. A semibatch reactor, where hydrogen peroxide and sulfuric acid were added, was found to be the most suitable configuration. To determine the optimum operating conditions and scale up the epoxidation or carbonation processes, it requires the database of different physicochemical properties, i.e. viscosity, density, refractive index, or specific heat capacity and the evolutions of these properties with the temperature. However, this information is absent in the literature. For this study, the evolution of these properties with temperature and compositions (double bond, epoxide and carbonated groups concentration) was determined for three vegetable oils and their corresponding epoxidized and carbonated forms (cottonseed oil, linseed oil and soybean oil). Density and refractive indices of these oils were found to vary linearly with temperature. Based on the measurement of changes in viscous stresses with shear rates, these oils were found to be Newtonian fluids. It was demonstrated that specific heat capacity follows a polynomial equation of second order with temperature. Based on these results, it was demonstrated that some correlations could be used to predict the evolutions of these physicochemical properties at different composition and temperature based on the knowledge of the property of the pure compounds
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Carrasquillo, Katherine V. "Molecular Interpretation of a Trigger for Controlling an Amine Isocyanate Polyurethane Reaction." 2015. https://scholarworks.umass.edu/masters_theses_2/266.
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The temperature profile needed to complete the reaction between the sodium-diamine complex and the isocyanate terminated prepolymer has been established. The sodium diamine complex has the advantage of blocking the nearly instantaneous reaction between the diamine and isocyanate from taking place until it is released at elevated temperatures. Because of its low melting temperature (~40 °C) and its low molecular weight (low viscosity), this chain extension reaction is not dependent on the participation of the prepolymer. Instead, the rate of reaction is dependent on the dissolution of the 4,4’-methylenedianiline (MDA) complex into the system. The dissolution of the MDA complex has been demonstrated to be strongly dependent on particle size. Both the plasticizer Bis(2-ethylhexyl) adipate and the quaternary ammonium compound found in soy lecithin play crucial roles for this reaction. The quaternary ammonium compound is crucial in the dissolution of the complexes. Although the plasticizer has been shown to dissolve the complex to a small extent, the principal role of the plasticizer is to disperse the complexes and to prevent their agglomeration. Other additives such as Dimethyl Sulfoxide (DMSO) have demonstrated to be highly efficient in dissolving the complex. However its effectiveness limits the mixing window needed before reaction take place, resulting in a disadvantage.
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Hung, Liao-Jui, and 廖睿宏. "The study of thermally reversible Polyurethane via Diels-Alder Reaction." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3f475d.
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碩士國立臺灣科技大學
材料科學與工程系
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Self-healing materials can repair cracks caused by mechanical damage through external stimuli. and have the advantages of increasing material safety, extending service life and saving renovation costs. Polyurethane (PU) is a kind of copolymer with soft and hard segment. The physical properties can behave from rigid to soft and widely use in daily life. The advantage of Diels-Alder (DA) reaction is moderate reaction temperature and well reversibility. The introduction of DA reversible covalent bond in PU molecular chain can have excellent self-repairing ability. The retro-DA bond-breaking reaction can shorten the molecular chain to fill the crack. Then the DA re-bonding reaction can increase the molecular chain to restore the mechanical properties. However, during the crack healing the viscous flow state causes a significant drop in mechanical properties. The lack of elasticity makes the material susceptible to deformation by external forces. In this experiment, a linear PU molecular chain containing a thermally reversible Diels-Alder bond (DAPU) was used as a healing agent can healing the crack of bulk material. Moreover, a thermosetting crosslinked PU (CPU) was used as a backbone to enhance the elasticity during crack healing. Both component blend together with a weight ratio of 1:1. Observed by optical microscopy, the temperature required to fill the crack increases because the CPU network structure will constrain the thermal motion of the linear DAPU molecules. From the tensile test, the thermosetting CPU is composed of non-reversible covalent bonds, and the material crack is filled by linear DAPU. The tensile strength recovery rate decreased from 96.7 % to 68.2 % compared with pure DAPU. According to dynamic thermomechanical analysis, the blend of DAPU and CPU can let the material maintain a certain elastic modulus during the crack repairing. This kind of self-healing material can extend applications such as fuel storage bladders, inflatable structure membrane and architectural building envelopes.
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Niyogi, Debdarsan. "Modeling Of Bubble Size Distribution In Reaction Injection Molded Polyurethane Foams." Thesis, 1997. http://etd.iisc.ernet.in/handle/2005/1780.
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