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1
Wang, Jiann-Hua. "Ultraviolet Raman spectroscopic and fluorescence lifetime studies of polymers and polymer additives." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621931.
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Ren, Xianjie ren. "Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129.
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Terranova, Steven Alfred. "Cross-Linking Additives as Smoke Suppressants for Poly(Vinyl Chloride)." W&M ScholarWorks, 1993. https://scholarworks.wm.edu/etd/1539625814.
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Grabowski, Daniel W. "Drag reduction in pipe flows with polymer additives /." Online version of thesis, 1990. http://hdl.handle.net/1850/10599.
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DeButts, Barbara Lynn. "Plant proteins as multifunctional additives in polymer composites." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/89011.
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Wheat gluten, wheat gliadin, and corn zein agricultural proteins were evaluated as multifunctional additives that: (1) provided reinforcement, (2) improved thermal stability, and (3) lowered the cost of polymer composites. Wheat proteins were utilized in two polymer matrices: poly(vinyl alcohol) (PVA) and synthetic cis-1,4-polyisoprene rubber (IR). The proteins were hydrolyzed and dispersed in the polymer matrix, where they cooperatively self-assembled into nanostructures called amyloids. Amyloids have the potential for high rigidity and stability due to high β-sheet content. In Chapter II, trypsin hydrolyzed wheat gluten (THWG) proteins were incubated in aqueous PVA solutions, then the composite solutions were air dried and compression molded into films. Anisotropic protein aggregates formed through a typical mechanism of β-sheet self-assembly, where a greater molding time and pressure and/or a lower PVA molecular weight allowed for more protein aggregation. The larger protein structures provided less reinforcement. In Chapters III and IV, THWG and trypsin hydrolyzed gliadin (THGd), a component protein in wheat gluten, were compounded in synthetic polyisoprene rubber to form nanocomposites. The reinforcement correlated to the protein β-sheet content and varied with protein concentration, protein batch preparation, processing temperature, and compounding time. The isotropic β-sheet containing structures were very thermally stable, even under harsh rubber compounding conditions. By optimizing the processing parameters uniform protein dispersion and optimal IR reinforcement were achieved, although the protein and IR phases had poor compatibility. In Chapter V, the THGd-IR composites were cured using a typical cure package and molding process. Protein aggregation into nanostructured β-sheets was observed during the curing process. Rubber reinforcement increased as a function of protein concentration and curing time. In Chapter VI, a hydrophobic protein (zein) was substituted for the hydrophilic protein (gliadin) used previously to improve protein-IR compatibility. The zein protein was better at reinforcing IR, while gliadin improved mechanical stability. Both zein and gliadin improved the thermal stability of IR. The results from Chapters II-VI showed an interesting concept: in situ filler formation in polymer matrices where the choice of protein, polymer, and processing conditions influenced the final morphology and composite properties.Doctor of Philosophy
We use plastics every day for a wide range of applications, from food packaging to automobile tires. Many of these plastics are composite materials, called “polymer composites,” meaning they are made of two or more chemically distinct materials where one material is a polymer. For reference, a polymer is a long chain molecule made of many (“poly-”) units (“- mer”). Polymer composites often contain additives which modify the properties of the polymer. For example, many soft polymers, such as tire rubber, need to be made stiffer and so a “reinforcing additive” is used to improve the stiffness of the rubber. Many composite materials are made stiffer so less material can be used. This process is called “lightweighting.” The automotive industry and food packaging industry use this process to reduce weight and fuel costs. In this research, plant proteins are tested as reinforcing additives in polymer composites. Plant proteins, such as wheat gluten, are abundant, non-toxic, sustainable, and can self-assemble into extremely small, stiff structures. For these reasons, plant proteins offer an environmentally friendly alternative to typical reinforcing additives. This dissertation shows that plant proteins can reinforce two polymers with very different properties. The first polymer is poly(vinyl alcohol) (PVA), which is biodegradable, hydrophilic (i.e., “water loving”), and is commonly used in flexible food packaging. The second polymer is synthetic cis-1,4-polyisoprene rubber (IR), which is non-biodegradable, hydrophobic (i.e., “water fearing”), and is commonly used in automotive tires. In Chapters II-V, the wheat gluten protein is hydrolyzed, i.e., chemically “chopped” into short chain peptides, to encourage the self-assembly of the plant protein into small, stiff structures. The self-assembled protein structures survive typical industrial processing techniques, such harsh rubber compounding conditions which involve high heat, pressure, and shear forces (i.e., the material is pushed in opposing directions). In Chapter VI, full corn and wheat proteins are incorporated into IR using standard industrial mixing and curing processes. The corn and wheat proteins reinforce the synthetic rubber and inhibit the degradation of the chemical structure of cured rubber under high heat. At certain protein concentrations, the proteins improve the elasticity and lessen the permanent deformation in the polymer composite. Together, Chapters II-VI show that proteins from diverse plant sources can be used to improve the performance of polymers with dissimilar properties.
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Liu, Chang. "Effect of Polymer Molecular Weight, Binary Processing Additives, Two-Dimentional Polymer on Efficiency of Polymer Solar Cells." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1396895752.
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Isaacs, Mark. "Nanoengineered polymer architectures for antimicrobial medical applications : novel additives." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/69607/.
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Silver is a clinically important, broad spectrum antibacterial, whose use extends back over several millennia. Its potent antibacterial activity, range of susceptible microorganisms, and lack of developed resistances, elevate silver as an exciting weapon in the fight against hospital acquired infections and so-called ‘superbugs’. The active, ionic form is efficacious at very low concentrations, thus controlling release rates offers potential durable, non-specific, antibacterial medical devices. This thesis examines a number of inorganic systems as potential slow-release, antibacterial silver nanocomposites for incorporation into polyurethane foam wound dressings. A range of silver core-silica shell nanocomposites were synthesised with tuneable dimensions, with porosity introduced into the silica shells, via base-etching or surfactant-templating producing disordered or ordered architectures respectively. An alternative system based on mesoporous SBA-15 silica was also investigated, which was employed as a scaffold for subsequent multilayer titania functionalisation, onto which mixed silver/silver carbonate nanoparticles were subsequently deposited. Detailed characterisation allowed fundamental structural-function relationships for silver dissolution kinetics and their associated impact upon antibacterial activity towards Gram-positive and Gram-negative bacteria including methicillin-resistant Staphylococcus aureus. Silver ion release rates are inversely proportional to silver crystallite size, with further governance via shell thickness and mesoporosity achievable in core shell systems. The intrinsic antibacterial activity of titania coated SBA-15 further enhances performance, independent of silver, whilst support macropore introduction increases silver particle dispersion. Antibacterial prowess of all materials demonstrates a strong activity correlation with dissolution kinetics, evidencing up to seven-fold logarithmic reductions in the bacterial concentrations within four hours. Materials were potent for > 24 hours, with the reverse micelle core-shell formulation showing continuous activity over a 14 day period. Comparative benchmarking indicates mesoporous silver core-silica shell architectures as promising candidates due to antibacterial longevity, manufacturing simplicity and cost, with their hydrophilic nature and small dimensions rendering them amenable to incorporation into compatible polyurethane foams.
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Saggar, Sandeep Amar. "Additives for Increased Atomic Oxygen Resistance in Cyanate Ester Resins." W&M ScholarWorks, 1999. https://scholarworks.wm.edu/etd/1539626216.
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Okopi, I. A. "Solubility and migration of stabilizing additives in polyolefins." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382571.
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This thesis describes a series of studies of the physical behaviour of commercially important stabilizing additives in polyolefins. A series of nickelthiocarbamates have been synthesised and their solubilities measured as a function of temperature in linear hydrocarbon solvents, low density polyethylene and isotactic polypropylene. The results are compared with predictions from a regular solution model. The loss of three benzophenone UV-stabilizers from supersaturated solution has been investigated with the aim of determining whether the loss is a diffusion controlled blooming or involves phase separation. Our data shows this phenomenon is a diffusion controlled blooming process. The volatilities of these same UV-stabilizers have been measured as a function of temperature. The solubility of a typical hindered amine (Tinuvin 770) has been investigated in hydrocarbon solvents and in polypropylene by infrared methods. Low solubility values were obtained in all cases. The diffusion of Tinuvin 770 in polypropylene has been monitored by an infrared method developed for the purpose and the diffusion coefficient estimated over a range of temperatures. Litp.rature data on solubility of additives together with our own data are critically reviewed and the effect of structure on solubility is analysed. Data on the benzophenone additives allows prediction of loss times and mechanisms to be made for the first time.
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Hodgson, Marcelle. "Emulsion polymerization of styrene in the presence of reversible addition-fragmentation chain transfer agents." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51739.
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Thesis (MSc)--Stellenbosch University, 2000.ENGLISH ABSTRACT: This work involves the study of the effects of Reversible Addition-Fragmentation Chain Transfer (RAFT) agents on the emulsion polymerization of styrene. The feasibility of RAFT as a method for obtaining controlled radical polymerizations in emulsion systems is also investigated. Both seeded and ab initio systems were studied with three RAFT agents of varying structure. Inhibition and retardation effects on addition of various amounts of the RAFT agents to the emulsion systems were observed and the trends noticed. The effect of the RAFT agents on the average number of radicals per latex particle was calculated from reaction rates. The effect of the RAFT agent on the molecular weight and the molecular weight distribution was monitored by gel permeation chromatography. Exit of free radicals from the latex particles proves to be a major feature in the studied RAFT emulsion systems. Fragmentation of the RAFT agent in the latex particles, gives rise to free radical species that can exit from the particle and enter other particles where they can either terminate instantaneously or propagate. The exit and termination processes presumably result in both the inhibition and retardation of the emulsion polymerizations. A linear increase in Mn with conversion is observed, however the low concentration of RAFT agent in the latex particles is responsible for the obtained number average molecular weights being much higher than predicted. The low concentrations of RAFT agents in the latex particles is also responsible for the broad molecular weight distributions that are obtained. Reaction conditions for RAFT experiments should to be chosen so that the effects of exit processes are minimized and that the RAFT agent is primarily situated in the latex particles. These conditions must be met if the RAFT process is to be successful as a method of controlled radical polymerization in emulsions.
AFRIKAANSE OPSOMMING: Hierdie navorsing behels die studie van die effek van In bygevoegde addisie-fragmentasie kettingsoordragsreagent (RAFT1) op die emulsie polimerisasie van stireen. Die uitvoerbaarheid van RAFT as 'n metode om gekontroleerde radikale polimerisasies in emulsiesisteme te verkry is ook ondersoek. Eksperimente met drie RAFTkettingoordragsreagente van gevarieerde strukture is uitgevoer in beide seeded en ab initia sisteme. Die effek van die RAFT-reagent op die inhibisie en vertraging van die emulsie polimerisasie is waargeneem en die invloed van RAFT op die gemiddelde aantal radikale per partikel is bepaal. Die ontwikkeling van die molekulêre massa en die molekulêre massadistribusie is waargeneem deur middel van gel permeasie- kromatografiese tegnieke. Die ontsnapping van vrye radikale vanuit die partikels was 'n belangrike faktor in RAFT emulsiesisteme wat ondersoek is. Hierdie radikale is gegenereer deur die fragmentasie van die oorspronklike RAFT-reagent. Fragmentasie van die RAFT-reagent in die lateks partikels lei tot die vorming van vrye radikale spesies wat uit een partikel kan ontsnap en ander partikels kan binnedring waar dit onmiddellik kan termineer of propageer. Die ontsnappings- en terminasieprosesse van vrye radikale lei oënskynlik tot die inhibering en vertraging van die emulsie polimerisasie. 'n Lineêre verhoging in die gemiddelde molekulêre massa tydens konversie is waargeneem, alhoewel die Mn-waardes baie hoër was as wat verwag is. Die verskil kan toegeskryf word aan die klein hoeveelhede van die RAFT-reagent wat in die partikels teenwoordig is. Hierdie lae RAFT-konsentrasies is ook verantwoordelik vir die breë molekulêre massa distribusie wat waargeneem is. Vir die RAFT-proses om suksesvol te wees in gekontroleerde radikale polimerisasies in emulsies, moet reaksie kondisies so gekies word dat die ontsnapping van vrye radikale tot 'n minimum beperk word en die RAFT-reagent hoofsaaklik in die lateks partikels teenwoordig is.
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Lott, Joseph Robert. "Design, Synthesis and Incorporation of Functional Additives into Multilayered Polymer Films." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1295673932.
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Tanaka, Yasuyuki. "Selective Crystallization of CaCO_3 in the Presence of Polymer Additives." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150251.
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OCAÑA, LADY MARYLIN PUMISACHO. "TURBULENCE MEASUREMENTS IN PIPE FLOW WITH DRAG REDUCING POLYMER ADDITIVES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18180@1.
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O fato que a dissolução de pequenas quantidades de polímero de cadeias
moleculares longas em fluxo turbulento através dutos reduz drasticamente o atrito, é
conhecido há muitos anos. No entanto, muitos aspectos fundamentais deste fenômeno
ainda não são bem compreendidos, particularmente os mecanismos de interação entre o
polímero e o solvente. O presente trabalho descreve os resultados de um estudo voltado
para fornecer informações detalhadas sobre as características da turbulência no
escoamento de água com aditivo polimérico através de tubos. Para isto, foram realizados
experimentos para medir o campo instantâneo de velocidade em uma seção longitudinal
de um tubo, empregando a técnica de Velocimetria de Partículas por Imagem, PIV, em
sua versão bidimensional. As grandezas estatísticas turbulentas foram obtidas a partir de
uma série de 2.500 campos instantâneos de velocidade medidos para cada configuração
de escoamento caracterizada pelo número de Reynolds e pela concentração de polímero
em água. Foram medidos campos de velocidade média, de flutuações de velocidade dadas
por valores RMS e perfis de tensão turbulenta. Especial atenção foi dedicada ao projeto
da seção de testes, de modo a minimizar as distorções de imagem junto à parede do
tubo. Na região de visualização, a parede do tubo foi usinada com uma espessura de 500
μm para minimizar a refração óptica da superfície curva. Esta tubulação de paredes finas,
em combinação com uma caixa de acrílico preenchida com água posicionada ao redor do
tubo, permitiu medições de velocidade com a técnica PIV em posições a cerca de 250 μm
da parede do tubo, o que equivale a menos de 10 unidades em coordenadas de parede. A
análise dos campos de deslocamento das partículas traçadoras nas imagens capturadas
empregou uma combinação da técnica PIV clássica com técnicas de acompanhamento de
partículas, resultando em medidas com resolução espacial substancialmente melhorada.
Os testes foram conduzidos para uma faixa de números de Reynolds de 23000 a 80000, e
para 20 ppm de concentração de polímero Superfloc A110 em água. As medidas da queda
de pressão indicaram reduções no coeficiente de atrito da ordem de 50%. Os resultados
obtidos demonstraram que a presença do aditivo polimérico produz alterações na
estrutura do escoamento turbulento junto à parede, o que se reflete em mudanças na
camada de amortecimento do perfil de velocidade.The fact that dissolving a minuscule amount of long-chain polymer molecules in a turbulent pipe flow reduces drastically the frictional drag, has been known for many years. However, many fundamental aspects of this phenomenon are still not well understood, particularly the mechanisms of interaction between the polymer and the solvent. The present paper describes the results of an ongoing project aimed at providing detailed information on the turbulence characteristics of turbulent pipe flow of water with polymer additive. To this end, an experimental program was conducted for measuring the instantaneous longitudinal velocity field employing a two-dimensional Particle Image Velocimetry technique – PIV. Turbulence statistics were obtained from a series of approximately 2500 instantaneous velocity fields measured for each flow configuration characterized by the pipe Reynolds number and the polymer concentration. Profiles of Time-averaged velocity, RMS velocity fluctuations and turbulent shear stresses were measured. Special attention was dedicated to the test section design so as to minimize image distortions close to the pipe wall. At the visualization region, the pipe wall was machined to a thickness of 500 μm to minimize optical refraction of the curved surface. This thin-walled pipe in combination with a plexiglass box filled the water surrounding the pipe, allowed for PIV velocity measurements at approximately 250 μm from the pipe wall, which is equivalent to less than 10 wall units. A combination of classical PIV with particle tracking techniques was employed in the analysis of the particle displacements, what substantially enhanced the spatial resolution of the measurements. Tests were conducted for a Reynolds number range from 23000 to 80000, and for 20 ppm of Superfloc A110 polymer in water. Wall pressure measurements indicated reductions in the friction factor of the order of 50%. The results obtained demonstrated that the presence of the polymer additive alters the turbulence structure at the wall, what produces a shift in the buffer layer of the velocity profile.
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Shallcross, Laura. "Investigating the interactions of nanoscale calcium phosphates with polymer additives." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/16902/.
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Islam, Shahida. "Time controlled photo-oxidation of polyolefins by polymer bound additives." Thesis, Aston University, 1992. http://publications.aston.ac.uk/9770/.
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A variety of iron compounds containing vinyl or thiol functional groups (used as photoactivators) have been synthesised and some of these were successfully bound to both polyethylene and polypropylene backbones during processing in the presence of peroxide and interlinking agent. Concentrates (masterbatches) of the photoactivators in PP and PE were prepared and the pro-oxidant effect of the diluted masterbatches in absence and presence of an antioxidant was evaluated. An antioxidant photoactivator (FeDNC ) was found to sensitise the photoactivity of pro-oxidants (Metone A / Metone M) whereas an antioxidant (ZnDNC) was found to stabilise the polymer (PP and PE) containing both of these combinations. It was observed that the lower concentration of FeDNC sensitises the stability of the polymer containing very small concentration of NiDNC whereas higher concentration of FeDNC stabilises the polymer (LDPE) containing same amount of NiDNC compared to FeDNC alone. The photostability of unstabilised PP containing FeAc could be varied by varying the concentration of ZnDEC. Both the induction period and the UV - life time of the polymer increased by increasing concentration of ZnDEC. It is suggested that ligand exchange reaction may take place between FeAc and ZnDNC. A polymer bound UV stabiliser (HAEB) and a thermal stabiliser (DBBA) were used with a non extractable photoactivator (FeAc) in PP. Small concentrations of the stabilisers (HAEB and DBBA) in combination with the photoactivator (FeAc) sensitise the polymer. The antioxidant present in commercial polymer (LDPE and PP) was found to be of a hindered phenol type, which was found to antagonise with ZnDNC when used in combination with the photoactivators.
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Sonawane, N. R. "Synthesis, characterisation and application of nanoparticulate additives for vinyl polymer coatings." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2011. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3787.
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Smith, Susan H. "Extraction of Additives from Polystyrene and Subsequent Analysis." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36774.
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The extraction of fifteen (15) polymer additives with supercritical carbon dioxide which are used as antioxidants, uv stabilizers, process lubes, flame retardants and antistats from eight formulations of polystyrene is demonstrated and compared to traditional dissolution/precipitation extractions. The purpose of the study was twofold: 1) the development of a high performance liquid chromatography (HPLC) method(s) for the additives and 2) the determination of the viability of supercritical fluid extraction (SFE) for the additives from polystyrene.
Separation of some of the additives was achieved using reversed phase liquid chromatography. Nine of the additives were assayed in this manner while, the remaining six additives could not be assayed using reversed phase liquid chromatography. In order to develop an extraction method for the additives, the effects of static extraction time, CO2 density, and temperature were first investigated. These preliminary extractions revealed that a static extraction period which afforded an opportunity for the polymer to swell combined with a high CO2 density and extraction temperature above the glass transition (Tg) yielded quantitative recoveries of the additives. Triplicate extractions of the various polystyrene formulations matched additive recoveries obtained by the traditional dissolution/precipitation method.Master of Science
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Dogan, Mehmet. "Effect Of Polymer Additives On The Physical Properties Of Bitumen Based Composites." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607531/index.pdf.
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Polymer modified bitumen is a binder obtained by the incorporation of various types of
polymers in bitumen using mechanical mixing or chemical reactions. There are several
factors affecting the properties of polymer modified bituminous composites such aschemical composition of bitumen, kind of polymer and filler, compatibility of bitumen and polymer, amount of bitumen, polymer and filler, particle size of filler and process conditions. The main objective of this study is to determine the effects of polymer type and concentration on mechanical, thermal, properties and morphologies of bitumen based composites. It was also aimed to determine the effect of process temperature on mechanical and thermal properties of bituminous composites. Bituminous composites were prepared by using Brabender Plastic Coder, PLV 151. Mixing was made at two different temperatures (150 º
C and 180 º
C) at 60 rpm for 20 minutes. Three different kinds of polymer and four different polymer concentrations were used to understand the effect of polymer type and polymer concentration on bituminous composites properties. Low density polyethylene (LDPE), styrene-butadiene-styrene copolymer (SBS) and ethylene-vinyl-acetate (EVA) were chosen as polymer. The compositions were adjusted as the polymer volumes were equal to 5%, 10%, 20% and 50% of bitumen volume. According to the test results, addition of polymer increases the mechanical properties, reduces the melt flow index and thermal conductivity values of bituminous composites. Morphological analysis results show that, fibrillation occurs at tensile fractured surfaces of composites which contain LDPE and EVA when the polymer concentration reaches 20% of bitumen volume.
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Soravia, Valeria. "Towards the circularity of polymer packaging." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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This thesis project was held at the Department of Civil Engineering and Geosciences at Delft University for a total duration of four months. The project was born from a collaboration between the University of Bologna and Delft, which has been in the works for a long time.
The thesis project is also part of a six-year project that sees the collaboration of several Dutch institutes with the aim of creating new technologies and improving the quality of plastic packaging specifically when it is finished the recycling process so that it can be reused.
The paperwork is structured to provide, through the first chapter, an overview of the current state of plastic and packaging production and to introduce the concept of circular economy, which has now become fundamental in today's economy.
The next chapter will be devoted to the understanding of the project, the methodology used, and a thorough analysis of the actors involved in the standardization scenario will be carried out to understand the importance and the obstacles that need to be faced nowadays. Finally, the theme of product design will be deepened, which is fundamental to their proper recycling.
The third chapter presents a study of the literature on those that are the most used polymers today in the packaging industry. Particular attention is given to the characteristics of the material. The second part of the chapter deepens the theme of additives and their characteristics, cataloged following extensive research.
The fourth chapter continues with a description of the main steps involved in the recycling process and the various types of processes. The intention is to deepen what is happening in the various phases and what are the most problematic for the output quality.
Finally, the project conclusions and the opinions of some experts who have been consulted during these months of research and study will be presented.
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Zeybek, Serife. "Experimental Investagation Of Drag Reduction Effects Of Polymer Additives On Turbulent Pipe Flow." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606370/index.pdf.
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Since the discovery of the drag reduction effects of even small amount of macromolecules in solutions in turbulent pipe flows, there have been many experimental and theoretical studies in order to understand mechanisms behind this phenomenon. Theories have been proposed based on the observations on the change in the characteristics of the turbulent flow near the pipe wall where friction of the momentum transfer between the flow and the conduit takes place.
In this study drag reduction in fully developed turbulent pipe flow with four concentrations (200 to 500 wppm) of low molecular weight Sodium Carboxymethylcellulose (CMC) in aqueous solutions was investigated experimentally. Drag reduction was determined by pressure drop measurements. In order to observe the impact of the presence of CMC on the flow, Ultrasound Doppler Velocimetry (UDV) was employed to monitor the instantaneous velocity distributions. UDV is a non-invasive technique allowing one to obtain quick velocity profiles. Experimental measurements were used to calculate Fanning friction factor and radial distributions of the axial time-averaged velocity, velocity fluctuation (turbulent intensity) and eddy viscosity.
The drag reduction level was determined through the Fanning friction factor versus Reynolds number data. Velocity data could be obtained as close as 3 mm to the wall by UDV.
Two impacts of increasing CMC concentration on the flow field, hence pressure drop, were observed. The first effect was the decrease of the mean velocity gradient especially near the wall with increasing polymer amount which in turn gave rise to lower friction factor or pressure drop. In addition smaller eddy viscosities were obtained in the flow. The second impact of the polymer addition was on the velocity fluctuation or turbulent intensity variation along the radial distribution. An increasing trend in turbulence intensity in the turbulent core with polymer addition was observed. This was in agreement with the earlier studies in which similar turbulence behavior was observed in addition to the suppression of the turbulent intensities near the wall
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Furuya, Tsutomu. "Structure Formation and Physical Properties of Aqueous Polymer Solutions and Hydrogels with Additives." Kyoto University, 2019. http://hdl.handle.net/2433/236625.
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Bacchi, Ataís 1986. "Resin cements modified with thiourethane polymer additives = cement layer and bonding interface properties." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288589.
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Orientador: Rafael Leonardo Xediek ConsaniTexto em português e inglês
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo neste estudo foi formular cimentos resinosos a partir de oligômeros tiouretanos, com o propósito de melhorar as propriedades mecânicas do material e minimizar a contração e a tensão de polimerização. Materiais fotopolimerizados e de ativação dupla foram avaliados. Dois oligômeros foram sintetizados ao combinar 1,6-hexanodiol-diisocianato (HDDI) (alifático) com pentaeritritol tetra-3-mercaptopropionato (PETMP) ou 1,3-bis(isocianato-1-metiletil) benzeno (BDI) (aromático) com trimetilol-tris-3-mercaptoproprianato (TMP), na proporção de 1:2 de isocianato e tiol, mantendo grupos tiol pendentes. Inicialmente, 10-30% em peso de ambos os tiouretanos foram adicionados à matriz orgânica formada por BisGMA-UDMA-TEGDMA (nas proporções 50-30-20%, em peso) para o cimento experimental fotopolimerizado. A este, 25% em peso de partículas inorgânicas foram adicionadas. Para o cimento de cura dual, composto pela mesma matriz orgânica e partículas de carga, e para dois materiais comerciais ¿ RelyX Veneer e RelyX Ultimate (3M Espe) - apenas a versão aromática em 10 e 20% em peso foi avaliada. Para todos os materiais, as propriedades mecânicas foram avaliadas através do teste de flexão por três pontos (ISO 4049) para a resistência à flexão (RF), módulo de elasticidade (E) e tenacidade (T). A tenacidade à fratura (KIc) foi avaliada em amostras entalhadas (ASTM Standard E399-90). A tensão de polimerização (TP) foi avaliada usando o aparelho Bioman. Os materiais fotopolimerizados foram avaliados quanto à contração de polimerização (CP) pelo método do disco aderido e a cinética de polimerização (grau de conversão (GC), taxa máxima de polimerização (Rpmax) e vitrificação) avaliadas por infravermelho. A união de uma cerâmica vítrea e um compósito restaurador indireto à dentina foi avaliada com o cimento comercial dual com 0, 10 e 20 % de tiouretano. Os resultados foram submetidos à Análise de Variância e teste de Tukey (?=5%). Quanto ao GC, ocorreu aumento pela utilização da versão alifática nos cimentos experimentais fotoativados; entretanto, a versão aromática não promoveu alteração relevante no GC final dos materiais. Rpmax foi menor nos grupos tiouretanos sendo também significantemente menor para os alifáticos quando comparados aos aromáticos. Apesar de os tiouretanos influenciarem a vitrificação (p=0,035) no cimento experimental, os resultados não foram conclusivos pela análise de Tukey. No cimento comercial foi observado aumento da vitrificação pelo uso do oligômero. Nos cimentos experimentais, RF aumentou com o oligômero aromático e 20% em peso do alifático nos cimentos fotopolimerizados; para E, a versão aromática no cimento com ativação dupla e 10% em peso no material fotopolimerizado causou aumento nos valores. Os materiais comerciais tiveram redução de E com 20% em peso de oligômero, decorrente da redução da proporção de carga inorgânica da matriz. Aumento significante em tenacidade ocorreu nos grupos alifáticos no material fotopolimerizado e para 20% em peso de aromático no cimento dual. K1c aumentou significativamente em ambos os materiais experimentais contendo tiouretano em ambas as concentrações, sendo mais pronunciada em alifáticos na versão fotopolimerizada. Ainda, KIc aumentou com 20% em peso do oligômero em materiais comerciais. A CP reduziu significantemente nos grupos tiouretanos, especialmente para o oligômero alifático no cimento experimental fotopolimerizado. A TP reduziu com os oligômeros de maneira mais acentuada para alifáticos no cimento experimental fotopolimerizado. O uso dos aromáticos em cimentos de ativação dupla também causou redução na TP, e quando com 20% em peso nos materiais comerciais. A modificação do cimento comercial de ativação dupla com 20% em peso do oligômero aromático aumentou a adesão do compósito indireto e da cerâmica vítrea à dentina coronária. Em geral, oligômeros tiouretanos melhoraram as propriedades dos cimentos resinosos avaliados
Abstract: The aim of this study was to formulate resin cements with thio-urethane oligomers to improve mechanical properties and minimize shortcomings related to the volumetric shrinkage and polymerization stress. Light- and dual-cured materials were evaluated. Oligomers were synthesized by combining 1,6-Hexanediol-diissocyante (aliphatic) with pentaerythritol tetra-3-mercaptopropionate (PETMP) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (aromatic) with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiols. Oligomers were added at 10-30wt% to BisGMA-UDMA-TEGDMA (5:3:2). 25wt% silanated inorganic fillers were added. The dual-cured cement, composed by the same organic matrix and filler particles, and for two commercial cements (RelyX Veneer e RelyX Ultimate; 3M Espe) were only evaluated with the addition of the aromatic version in 10 and 20 wt%. For all materials, the mechanical properties were evaluated by the three-point bending test (ISO 4049) for the flexural strength (FS) elastic modulus (E) and toughness (T). The fracture toughness was evaluated with notched specimens (ASTM Standard E399-90). The polymerization stress (PS) was evaluated in the Bioman. For the light-cured materials, the volumetric shrinkage (VS) was evaluated by the bonded-disc method and the polymerization kinetics ¿ degree of conversion (DC), maximum rate of polymerization (Rpmax) and vitrification ¿ evaluated by near-infrared (NIR). The bonding of a glass ceramic and an indirect composite to dentin were evaluated with the dual-cured commercial cement with 0, 10 and 20 wt% of thio-urethane. Data were analyzed with ANOVA and Tukey¿s test (?=5%). Regarding the DC, an increase was observed in the light-cured materials containing the aliphatic version. The aromatic oligomer did not promote relevant influence the materials. Rpmax was lower for thio-urethane groups being also significantly lower for the aliphatic group when compared to the aromatic. ANOVA has shown the thio-urethane influencing the vitrification (p=0.035) in the experimental cement, but the results were not conclusive by the Tukey¿s test. For the commercial cement, an increase in the vitrification was observed in the thio-urethane-modified group. For experimental cements, FS increased with the use of 10-30 wt% aromatic oligomer and with 20 wt% of aliphatic for light-cured cements. E was only higher for the aromatic version at 10 wt%. The commercial cements presented a reduction in E with 20 wt% of oligomer caused by the reduction in the filler proportion. A significant increase in T occurred in the aliphatic groups for the light-cured group and for 20 wt% of aromatic in the dual-cured cement. KIc significantly increased in both experimental materials formulated with thio-urethane for both concentrations, being more evident for the aliphatic group in the light-cured version. KIc also increased with the aromatic oligomer in commercial materials. The VS was significantly reduced in the thio-urethane groups, mainly for the aliphatic version in the light-cured cement. The PS decreased in the groups formulated with oligomers in the light-cured experimental materials, being also significant for aliphatics. The use of aromatic oligomer also reduced the PS when added to a 20 wt% proportion of organic matrix. The modification of a dual-cured commercial cement with 20wt% of aromatic oligomer led to an increase in the bond strength of an indirect composite and a glass ceramic to the coronal dentin. Thus, it can be concluded that thio-urethane oligomers improved the properties of resin cements
Doutorado
Protese Dental
Doutor em Clínica Odontológica
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Lee, William K. "Solid-gel interactions in geopolymers." Connect to thesis, 2002. http://repository.unimelb.edu.au/10187/1071.
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This is partly because the requirements for such an ultimate material change with people’s perception about its properties as well as its environmental impact. Thus, the once-believed ultimate Portland cement binder is now becoming unacceptable for a number of reasons including poor durability as well as severe environmental impact during production. Thus, an improved mineral binder is required by modern society to serve the same purposes as the existing Portland cement binder, as well as to reduce the current environmental impact caused by Portland cement production.Geopolymerisation is such a ‘green’ technology capable of turning both natural ‘virginal’ aluminosilicates and industrial aluminosilicate wastes, such as fly ash and blast furnace slag, into mechanically strong and chemically durable construction materials. However, the source materials for geopolymer synthesis are less reactive than Portland cement clinkers and the chemical compositions of these source materials can vary significantly. Consequently, product quality control is a major engineering challenge for the commercialisation of geopolymers.
This thesis is therefore devoted to the mechanistic understanding of the interfacial chemical interactions between a number of natural and industrial aluminosilicates and the various activating solutions, which govern the reactivity of the aluminosilicate source materials. The effects of activating solution alkalinity, soluble silicate dosage and anionic contamination on the reactivity of the aluminosilicate source materials to produce geopolymeric binders, as well as their bonding properties to natural siliceous aggregates for concrete making, are examined. In particular, a new set of novel ‘realistic’ reaction models has been developed for such purposes. These reaction models have been further utilised to develop a novel analytical procedure, which is capable of studying geopolymerisation on ‘real’ geopolymers in situ and in real time. This novel procedure is invaluable for the total understanding of geopolymerisation, which is in turn vital for effective geopolymer mix designs.
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Jeng, Jong Paul. "Mechanisms of poly(vinyl chloride) fire retardance and smoke suppression induced by copper additives." W&M ScholarWorks, 1995. https://scholarworks.wm.edu/etd/1539623866.
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The purpose of this study was to elucidate the mechanisms of PVC fire retardance and smoke suppression induced by copper additives.;The experimental approaches involved: (1) the use of activated copper (Cu{dollar}\sp0{dollar}) to study PVC model-compound reactions and the crosslinking of PVC and (2) the pyrolysis of PVC model compounds in the presence of several copper additives in order to examine all of the possible chemical reactions involved in the formation of heavy products.;The results obtained from experiments with activated copper and allylic chloride model compounds suggest that the reductive coupling mechanism is a viable process in PVC. The Cu{dollar}\sp0{dollar} that caused the coupling was either (a) a slurry resulting from the reduction of CuI {dollar}\cdot{dollar} P(n-Bu){dollar}\sb3{dollar} with lithium naphthalenide or (b) a film created by the pyrolysis of copper(II) formate. Significantly, both the slurry and the film were also demonstrated to be capable of promoting the extensive crosslinking of PVC itself.;In small-scale sealed-ampule model compound pyrolysis experiments, several chemical reactions were revealed that may account for the crosslinking that occurs in copper-containing PVC. These reactions include Lewis-acid-catalyzed oligomerization and chloroalkylation, reductive coupling dimerization, alkene mono-halogenation (rechlorination), and aromatization.;For copper compounds, Lewis-acid catalysis is the major (if not the only) reaction pathway toward crosslinking; while in the case of high-purity copper metal, the reductive coupling mechanism apparently plays a major role in the crosslinking process.;Since the crosslinking of PVC is known to suppress the formation of the volatile aromatics whose combustion generates smoke, the results of this study indicate that copper-promoted Lewis-acid catalysis and reductive coupling dimerization will tend to prevent the evolution of smoke from the burning polymer.
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Ng, Yean Thye. "Electrically conductive melt-processed blends of polymeric conductive additives with styrenic thermoplastics." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/11016.
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The growing demand in portable and compact consumer devices and appliances has resulted in the need for the miniaturisation of electronic components. These miniaturised electronic components are sensitive and susceptible to damage by voltages as low as 20V. Electrically conductive styrenic thermoplastics are widely used in electronic packaging applications to protect these sensitive electronic components against electro-static discharge (ESD) during manufacturing, assembly, storage and shipping. Such ESD applications often require the optimal volume resistance range of ≥ 1.0x105 to < 1.0x108 Ω. The best known method to render styrenic thermoplastics conductive is by the incorporation of conductive fillers, such as carbon black but the main limitation is the difficulty in controlling the conductivity level due to the steep percolation curve. Thus the aim of this research is to develop electrically conductive styrenic thermoplastics by blending several styrenic resins with polymeric conductive additives to achieve optimal volume resistance range for ESD applications with the ease in controlling the conductivity level.
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Daniels, Leonard John. "The synthesis and evaluation of curing agents for use in epoxy modified Portland cement mortars." Thesis, Lancaster University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312635.
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Pepper, Stephen T. "The interaction of fillers and lubricants in rigid PVC compositions." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/13708.
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The physical properties of rigid PVC products can be related to formulation, preblending and processing characteristics. A fuller understanding between these interrelations involves investigation of a complete processing system from powder additives to end product. A knowledge of these relationships can lead to a optimisation of formulation aspects and processing conditions. Fillers and lubricants have often been incorporated into PVC compounds on a empirical basis, however in this investigation a wide range of compositions were carefully chosen and included a calcium carbonate filler at levels up to 40 phr. These were dry blended and then characterised by bulk density and filler content. The premix was processed using an instrumented twin screw extruder, a wide processing 'window' being chosen to provide a product range with large variations in fusion level. Further compounds were extruded, incorporating two different impact modifiers. The extrudates was assessed for degree of fusion by differential thermal analysis, solvent immersion and microscopy. The filler distribution, surface appearance and residual grain structure was observed using a range of microscopy techniques and the results related to operating conditions. A measure of fusion level was obtained from mast er curves of heat of fusion versus processing temperature'. The filler level did not influence the degree of fusion. Various mechanical properties of the pipe were assessed. Impact performance was measured using an instrumented falling weight impact tester and the subsequent fracture behaviour depended on the composition and fusion level. Impact properties were dramatically reduced at a critical filler content and ductile-brittle transition temperatures were obtained for the extrudates by testing at low and high temperatures. Tensile properties did not follow the trends observed during impact testing but indicated a progressive reduction in tensile properties with increasing filler content.
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Via, James C. "Applications of supercritical fluids to the extraction and analysis of oligomers and polymer additives." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38653.
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Moyo, Lumbidzani. "Fatty acid intercalated layered double hydroxides as additives for Jojoba oil and polymer matrices." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/25462.
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Fatty acid intercalated layered double hydroxides were used as additives for Jojoba oil and polymer matrices. The first phase of the study was to intercalate carboxylic acids (C14 to C22). These were successfully intercalated into layered double hydroxides (LDHs), with the formula [Mg0.7Al0.3 (OH) 2](CO3)0. 15•0.5H2O. The one-pot synthesis consistently yielded a bilayer intercalated product for the range of acids employed. The intercalated anions had an orientation tilt angle of 55–63°, depending on the length of the fatty acid chain. However, there is an indication that the anion exchange process employed in this study is accompanied by probable dissolution and recrystallisation of the LDH. This is supported by the different growth habits and sizes of platelets observed through scanning electron microscopy (SEM). Moreover, the organo-LDH platelets were found to have varying MII/MIII compositions, ranging from 1.65 to 6, indicating that the one-pot synthesis yields an array of mixed metal hydroxides. Polymer composites, containing 5% and 10 wt.% of stearate intercalated layered double hydroxides (LDH-stearate) and neat layered double hydroxides (LDH-CO3), were prepared via melt-compounding to explore the use of LDHs as an additive. The stearate modified starting material was bilayer-intercalated clay. During melt compounding, excess stearates were released and the clay reverted to a monolayer-intercalated form. Comprehensive characterisation and study of the fatty acid-intercalated LDH showed that these organoclay hybrids exhibit thermotropic behaviour. This behaviour ultimately leads to the exudation of excess fatty acid. The exuded stearates were found to have lubricating and plasticising effects on the poly(ethylene-co-vinyl acetate) (EVA) and linear low density polyethylene (LLDPE) matrices. Strong hydrogen bond interactions between the chains of poly(ethyleneco- vinyl alcohol) (EVAL) and the clay platelet surfaces overwhelmed the lubrication effect and caused an increase in the melt viscosity of this matrix. The notched Charpy impact strength of this composite was almost double that of the neat polymer. It appears that this can be attributed to the ability of the highly dispersed and randomly oriented nanosized clay platelets to promote extensive internal microcavitation during impact loading. The creation of a large internal surface area provided the requisite energy dissipation mechanism. The study also considered fatty acid-intercalated LDH as an argillaceous mineral for potential use as a rheological additive in Jojoba oil. A minimum of 20 wt.% LDH in Jojoba oil formulation was found to be stable, i.e. it did not form separate layers on standing. The viscosity of the neat Jojoba oil demonstrated Newtonian behaviour, whereas the modified LDH/Jojoba oil formulation shear thinned, which is a typical non-Newtonian behaviour. Viscosity as a function of temperature showed complex rheological behaviour for the long chain fatty acids C16 to C22. The viscosity increase is assumed to be due to a combination of three events, which include the formation and changes of LDH microstructures within the oil, the loss of excess fatty acids into the oil matrix, and the formation of fatty acid crystal networks. Shear action also induced some delamination of the clay platelets.Thesis (PhD(Eng))--University of Pretoria, 2012.
Chemical Engineering
unrestricted
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Yeasting, Kyle Douglas. "The Evaluation of Hybrid Slurry Resulting from the Introduction of Additives to Mineral Slurries." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3415.
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Drilled shaft construction often requires the use of drill slurry to maintain borehole stability during excavation and concreting. While drill slurry may be composed of fluids ranging from air to petroleum, drilled shaft construction typically makes use of water based drilling fluids. Although clean water may be utilized as a drilling fluid, a premixed slurry consisting of water, minerals, and/or polymers is more commonly used. Florida Department of Transportation (FDOT) specifications require the use of mineral slurry for all primary structures. The slurry resists the intrusion of groundwater, slows the outward migration of drilling fluid from the excavation, and aids in the removal of suspended soil cuttings. The mechanisms by which mineral slurries work are quite different from those of polymer slurries. Due to these differences, it is unclear whether a mineral based slurry, which has been fortified with polymers by manufacturers or enhanced through the addition of polymers in the field, behaves more like a mineral slurry rather than polymer slurry.
This thesis provides an overview of the methods used to measure physical slurry parameters of interest. These parameters include density, viscosity, pH, sand content, and filtration control. Methods employed to describe the slurry parameters include tools and instrumentation commonly used in both field and laboratory settings.
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Aquino, Eugene Canlas. "The Effects of the Exposure of Atomic Oxygen on Polymeric Material: I Siloxane Modified Epoxy Resins II Polyetherimide Films with Additives." W&M ScholarWorks, 1991. https://scholarworks.wm.edu/etd/1539625668.
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Wallmon, Tanya. "The Influences on the Optical Properties of Paperboard Due to Dye Additives." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-251452.
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In the paper industry the appearance and optical performance of coated and uncoated paperboard is important, therefore colour dyes are widely used to enhance the paperboard. In order to enhance the appearance of paper products, the dyes are added directly into the pulp and/or in the coating. This addition can lead to dye buildup in the white water system. The white water system recirculates back to the pulp and contains both chemicals, dye and fibers. A general assumption is, when the concentration of dyes builds up in the system, it can lead to changes of the optical properties. Previously studies have been conducted to investigate the white water system at Iggesund Paperboard Workington Ltd. mill. Suspicion of a potential dye buildup in the white water system arose because of notable changes in the optical properties of the collected samples. An assumption was, when the concentration of dye increases in the white water system, it led to changes of the optical properties. The purpose of this project was therefore to investigate if/how potential dye buildup occurred in the white water system at Iggesund paperboard Workington Ltd. Mill. The system will be analyzed for dye buildup and to see if it influences the optical properties of the coated paperboard as a final product as well as how quickly it builds up in the system. This report contains a theoretical background for relevant knowledge about the white water system and optical properties of paperboard. The methodology for this project was to collect samples from the boardmachines’ white water system and analyze them through laboratory trials. Collected data is presented in the form of diagrams, trends have been investigated to validate assumptions. The dye dosage point was also analyzed through laboratory trials, to confirm or deny whether it is possible to achieve an optimal dosage point. The analysis showed that there were changes in the optical properties in the white water over time, as a result of dye buildup. Due to the complex system and different parameters that may affect the system, the sample collection needs to be extended further for a more precise conclusion. Such as how the dye responds to longer shuts and addition of polymers. Apart from what influenced the optical changes in the white water system and may have affected the paperboard, when the top coating from the production is applied, no changes or variations cannot be seen. Therefore giving the conclusion, that the changes of the optical properties do not influence the paperboard as a final product.Kartong är bland de vanligaste materialen att använda vid paketering. Den optiska egenskapen hos kartong är viktig för att den ska se tilltalande ut, samt vara mottaglig för tryck. Användning av färg är vanligt förekommande inom pappersindustrin för att förbättra de optiska egenskaperna i obelagt papper och belagt papper. Färgen tillsätts vanligen direkt i pappersmassan och vid bestrykning av beläggningen. Dock kan det leda till övermättnad i bakvattnet när man tillsätter färgen direkt i massan, vilket i sin tur kan påverka och även förändra de optiska egenskaperna. Bakvattnet recirkuleras i processen tillbaka till massaflödet då vattnet fortfarande innehåller användbara kemikalier, färg och fibrer som kan ansluta sig till massaflödet igen. Skulle det ske förändringar av de optiska egenskaperna behöver doseringen av färgen förändras vid beläggningen, vilket i sin tur kan leda till överdosering av färgen. Tidigare studier gällande bakvattensystemet vid Iggesund Paperboard Workington Ltd. mill har gjorts. Förändringar i de optiska egenskaperna från samlade prover från bakvattnet resulterade i misstankar av en potentiell ökning av färg i systemet. Detta utmynnade i antagandet att den ökande koncentrationen av färg i bakvattensystemet, i slutändan orsakar optiska förändringar. Syftet med detta projekt var därför att undersöka denna potentiella färgökning i bakvattensystemet vid Iggesund paperboard Workington Ltd. Mill. Bakvattensystemet har analyserats för att se en ökad färgkoncentration och om dessa optiska förändringar påverkar slutprodukten, samt hur snabbt färgens koncentration ökar. Denna rapport innehåller en teoretisk bakgrund för bland annat bakvattensystemet samt de optiska egenskaperna hos kartong. Metodiken för projektet var att samla prover från kartongmaskinens bakvattensystem och att analysera dessa prover. Insamlad data presenteras i diagram och trender undersöktes, för att validera antaganden modellerades trender. Doseringen av färgen undersöktes genom försök, för att kunna bekräfta om det är möjligt att upptäcka en optimal doseringspunkt. Analyserna visar att det sker förändringar i dem optiska egenskaperna över tid, som ett resultat av en ökad koncentration av färg. Då systemet är komplext och olika parametrar kan ha påverkat, behöver denna undersökning förlängas för en säkrare slutsats. Till exempel hur långa stop och hur addition av polymerer påverkar processen. Bortsett från vad som påverkar de optiska förändringarna i bakvattnet och kan påverka slutprodukten, när kartongen bestryks med beläggning, kan inga förändringar/variationer ses. Därför ges slutsatsen, att förändringar i de optiska egenskaperna i bakvattnet inte påverkar kartongen som slutprodukt.
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Vongsaysy, Uyxing. "Studies on processing additives introduced to increase the efficiency of organic solar cells : selection and mechanistic effects." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0230/document.
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Les cellules solaires organiques à hétérojonction en volume (BHJ en anglais) font l'objet d'un grand intérêt car elles représentent une source d'énergie bon marché et renouvelable. Cependant, à cause des rendements généralement bas, ce type de cellule peine à intégrer le marché. Afin d’en augmenter le rendement, contrôler la morphologie des semi-conducteurs dans la BHJ représente un élément clé. Dans ce contexte, il apparaît, dans la littérature, que les additifs solvant permettent de contrôler cette morphologie et d'augmenter les rendements.Cette thèse a pour but de fournir une étude complète sur l'utilisation des additifs. Le couple de semi-conducteurs étudié est le poly(3-hexylthiophene) (P3HT)/[6,6]-phényl-C61butanoate de méthyle (PC61BM).Une première partie présente une méthode développée pour guider la sélection d'additifs parmi une liste de solvants. Cette méthode emploie les paramètres de solubilité de Hansen des semi-conducteurs. Elle est appliquée au système P3HT/PC61BM et résulte en l'identification de trois nouveaux additifs performants. Ensuite, des caractérisations structurales, électriques et optiques sont menées sur la BHJ et permettent d'identifier les effets des additifs. Les effets de ces additifs se révèlent être différents en fonction de l'architecture des dispositifs. L'origine de telles différences est corrélée aux variations de mobilités des porteurs de charge causées par les additifs. Des tests de photo-stabilité ont été menés et montrent que les additifs sont capables d'augmenter la stabilité des cellules solaires. L’origine de telles améliorations est étudiée. Enfin, l'étude est étendue à deux autres nouveaux polymères semi-conducteursPolymeric bulk heterojunction (BHJ) organic solar cells (OSCs) have attracted significant interest as a low cost and renewable technology to harvest solar energy. However, their generally low efficiencies are a barrier for their movement into commercial application. Controlling the BHJ morphology is a key step in the pursuit of higher OSC efficiencies. Processing additives have emerged as effective components for optimizing the BHJ morphology. This thesis provides a comprehensive study on the introduction of additives in the formulation of semiconductors. The semiconductor system studied is based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61 BM). First, a method was developed to guide the selection of additives from a large range of solvents. This method employs the Hansen solubility parameters of the semiconductors and was successfully applied to the P3HT/PC61 BMsystem. It resulted in the identification of three new efficient additives. Next, the mechanistic role of additives in influencing the BHJ morphology is investigated by performing structural, electrical and optical characterizations. Also, the effect of additives on OSC performance was found to depend on the type of the OSC architecture. Such differences were correlated to the variations in charge carrier mobilities caused by the additive. Furthermore, photo-stability tests, performed on different types of OSCs, showed that processing additives can improve the photo-stability. The origin of such improvement is investigated. Finally, the scope of this study is extended to two other donor semiconducting polymers
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Dumetz, Andre C. "Protein interactions and phase behavior in aqueous solutions effects of salt, polymer, and organic additives /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 284 p, 2008. http://proquest.umi.com/pqdweb?did=1456290971&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Thesis (Ph.D.)--University of Delaware, 2007.Principal faculty advisor: Abraham M. Lenhoff, Dept. of Chemical Engineering, and Eric W. Kaler, College of Engineering . Includes bibliographical references.
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Zestos, Alexander George. "Effects of Metal-Based Montmorillonite Clay and Zeolite Additives on the Fire Retardance and Smoke Suppression of Poly(vinyl Chloride)." W&M ScholarWorks, 2008. https://scholarworks.wm.edu/etd/1539626874.
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Greyling, Corinne Jean. "Electrospinning of polyacrylonitrile nanofibres with additives : study of orientation and crystallinity." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/3996.
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Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Polyacrylonitrile, (PAN), polymers are of interest due to their many unique characteristics in comparison to most other fibre forming polymers. The focus of this study was the effect of electrospinning variables and additives on their unusual thermal properties and internal molecular morphology with the objective of improving the performance of this fibre in industrial application, or at least contributing to the understanding of how the fibre processing variables affect the thermal performance. The process of electrospinning was used to process samples of PAN fibres with additives in order to determine their effect on the molecular orientation and crystallinity of the resultant nano- and micronsized fibres. The effect of additives in the forms of low molecular weight oligomers, blends of conductive polymers and nanoparticles and conductive salts (mainly copper and lithium based) on the molecular structure and thermal properties is reported. In addition the effect of certain electrospinning processing variables such as the PAN polymer grade, the type of solvent, the temperature, the spinning voltage and the spinning distance were evaluated in terms of their effect on the resultant fibre molecular structure. The crystallinity and molecular orientation are quantified using various analytical techniques including: Fourier-Transform Infra-Red Spectroscopy (FTIR); Differential Scanning Colorimetry; (DSC) Thermal Gravimetric Analysis, TGA, Scanning and Transmission Electron Microscopy; Wide-Angle X-ray Diffractometry, XRD, Small-angle Neutron Scattering; SANS, Solid-state 13C Nuclear Magnetic Resonance Spectroscopy; NMR, and Electron-spin Resonance Spectroscopy, ESR. The researcher has ascertained in this study that the orientation of electrospun PAN is comparable to that in commercial wet-spun fibres when the electrospinning field strength is greater than 0,75 kV per cm. The process of electrospinning leads to chemical degradation of the PAN polymer only previously noted by other fibre scientists after heating PAN fibres to more than 280 C. This is due to the high mechanical stress on the high surface area electospun fibres spun into an oxygen rich air atmosphere. The addition of certain salts, particularly lithium chloride and copper nitrate, to the PAN electrospinning dope by the researchers produced fibres with improved thermal stability in comparison to the control PAN samples with no additives. In addition these salts lower the endotherm for the production of carbonized fibres from PAN fibres and will therefore make more structured, stronger, high tenacity carbon fibres. The XRD revealed that through the addition of certain salts to disrupt the dipole interations in PAN, that fibres with a 2D hexagonal crystal structure can be electrospun and have a structure similar to wet spun PAN. It is shown that fibres in a non-aligned electrospun mat have a 3D crystal structure and lower molecular orientation that wet spun fibres. Some industrial applications of electrospinning using PAN fibres are developed and reported.
AFRIKAANSE OPSOMMING: Polyakrilonitrielpolimere (PAN) is van belang weens die baie unieke eienskappe wat hulle het in vergelyking met die meeste ander vesel-vormende polimere. Die fokus van hierdie studie op die effek van verskeie veranderlikes en byvoegmiddels op hul buitengewone termiese eienskappe en interne molekulêre morfologie, met die doel om die werksverrigting van hierdie vesel in industriële toepassings te verbeter, of ten minste by te dra tot die begrip van hoe die vesel-prosesveranderlikes die termiese werksverrigting beïnvloed. Die elektrospinproses is gebruik om monsters van PAN met bymiddels te prosesseer om vas te stel wat die effek sou wees op die molekulêre oriëntering en kristalliniteit van die gelewerde nano- en mikrongrootte vesels. Verslag word gelewer oor die effek van bymiddels in die vorm van oligomere met „n lae molekulêre gewig, mengsels van geleidende polimere en verskillende nano-partikels en geleidende soute (meestal koper- en litium-gebaseerd). Die effek van sekere veranderlikes in die elektrospinproses, soos die PAN polimeer-graad, die temperatuur, die tipe oplosmiddel, die spin-spanning en spin-afstand, is geëvalueer in terme van hulle effek op die vesels wat gelewer word. Die kristalliniteit en molekulêre oriëntering word gekwantifiseer deur verskeie analitiese tegnieke te gebruik, onder meer: Fourier-Transform Infrarooispektroskopie; Differensiële Skandeerkolorimetrie; Termiese Gravimetriese Ontleding; Skandeeringelektronmikroskopie; Transmissie Elektron Mikroskopie; Wye-hoek X-straal Diffraktometrie; Klein-hoek Neutronstrooiing; Vaste-toestand 13C Kern Magnetiese Resonansiespektroskopie; en Elektronspin Resonansiespektroskopie. Dit is in hierdie studie vasgestel dat die oriëntering van elektro-gespinde PAN vergelykbaar is met kommersiële nat-gespinde vesels as die elektro-spin veldsterkte groter is as 0,75 kV per cm. Die elektro-spin proses lei tot chemiese degradasie van die PAN polimeer, wat voorheen slegs deur ander vesel-wetenskaplikes waargeneem is nadat PAN tot meer as 280 C verhit is. Dit word veroorsaak deur die hoë meganiese spanning op die hoë-oppervlakarea vesels wat in „n suurstofryke lug-atmosfeer gespin word. Die byvoeging van sekere soute, veral litiumchloried en kopernitraat, by die PAN elektro-spin spinlak (dope) deur die navorser het vesels gelewer met verbeterde termiese stabiliteit in vergelyking met die kontrole PAN-monsters sonder bymiddels. Verder verlaag hierdie soute die endoterm vir die produksie van gekarboniseerde vesels uit PAN-vesels, en dit sal daarom meer gestruktureerde, sterker koolstofvesels met hoë taaiheid lewer. X-straaldiffraksieanalise het gewys dat gewone elekrospin vesels ‟n driedimensionele struktuur het maar as gevolg van die byvoeging van sekere soute, wat die dipoolinteraksies in PAN opbreek, dat vesels wat 'n soortgelyke tweedimensionele struktuur het as dié van groot skaalse kommersiële nat-spin vesels, maklik d.m.v. die elektrospinproses berei kan word. Enkele nywerheidstoepassings van elektrospin is ontwikkel, en beskryf.
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Szabang, Katrin. "Antistatische Ausrüstung von duroplastischen Kunststoffen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-120754.
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Da Kunststoffe im Allgemeinen einen spezifischen Oberflächenwiderstand von >10E12 Ω besitzen, müssen die Materialien zur Vermeidung von elektrostatischen Aufladungen bei Bauelementen der Elektroindustrie antistatisch ausgerüstet werden. Durch elektrostatische Aufladungen können die Bauelemente eine Beeinträchtigung ihrer Funktion erfahren und Personen gefährden. Weiterhin ermöglicht die Absenkung des spezifischen Oberflächenwiderstandes eine elektrostatische (Pulver-)Lackierung.
Für die Herstellung von Kunststoffen mit kleinem spezifischen Durchgangswiderstand ist der Zusatz von leitenden Substanzen, wie z. B: Leitfähigkeitsruß, Graphit, Eisenoxid-, Kupfer- oder Aluminiumteilchen, metallisierte Glasfasern oder –kugeln, Edelstahlfasern oder Kohlenstofffasern, üblich. Die Substanzen werden dabei physikalisch in die Polymermatrix eingemischt. Je höher der Volumenanteil der Additive für die benötigte Ableitfähigkeit bezogen auf die Gesamtrezeptur ist, desto größer ist jedoch auch der Einfluss dieser Additive auf die mechanischen Eigenschaften in Relation zum unadditivierten Ausgangsmaterial. Unterschiedliche Polaritäten und Oberflächenspannungen von Additiv und Matrix bedingen zudem Probleme bei der Homogenisierung der Additive in der Matrix. Eine homogene Verteilung über das Volumen ist jedoch Voraussetzung dafür mit möglichst wenig Additiv die Perkolationsschwelle zu erreichen. Aus dieser Sicht hat sich eine reaktive Ankopplung von leitfähigen Gruppen an Matrix- oder sonstige geeignete Rezepturbestandteile in der Vergangenheit, z.B. für MDF, als erfolgreicher Weg erwiesen.
Ziel war es, dieses Konzept auf duroplastische Kunststoffe zu übertragen und dessen spezifischen Oberflächenwiderstand von >10E12 Ω abzusenken. Im Rahmen dieser Arbeit sollten die Materialien SMC (Sheet molding compound) und Epoxidharzlaminate eine antistatische Ausrüstung erhalten.
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Kezirian, Michael Tevriz. "The effect of polymer additives on the hydrodynamic stability and nonlinear evolution of thin liquid films." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10615.
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Zhou, Lucy Ying Jr. "Quantitative Analysis of Additives in Low Density Polyethylene Using On-line Supercritical Fluid Extraction /Supercritical Fluid Chromatography." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36786.
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Polymer additives exemplify many classes of compounds which possess a wide variety of chemical (i.e., phenols, amides, esters) and physical (i.e., volatility, solubility) properties. They are incorporated into polyolefins and other such polymeric materials for a number reasons: (a) to prevent degradation by ultraviolet light, heat, and oxygen; (b) to aid in the processing of the polymer; and (c) to modify the physical properties of the polymer. Since the purity and amount of additive can affect polymer properties, it is very important to characterize and quantify additives in polymer products. Traditional liquid solvent/polymer extraction methods, which involve dissolution/precipitation, are time-consuming, uneconomical, and the recoveries are significantly lower than 90%.
In recent years, analysis with supercritical fluids (SFs) has emerged as an alternative analytical technique because SFs afford higher diffusivity and lower viscosity. In this research, an on-line Supercritical Fluid Extraction (SFE)/Supercritical Fluid Chromatography (SFC) system was assembled to provide efficient extraction and separation of polymer additives with quantitative results. The effects of various SFE/SFC parameters, such as trapping temperature, injection temperature, extraction pressure and temperature, dynamic extraction time, and fluid flow rate on extraction and separation efficiencies of different additive standards (i.e., BHT, BHEB, Isonox 129, Irganox 1076 and Irganox 1010) were investigated. Optimized conditions were employed to quantitatively extract additives from LDPE. Identification of additives was performed by comparing the retention time with each additive standard. Results obtained from on-line SFE/SFC were compared to results from off-line SFE/High Performance Liquid Chromatography (HPLC) and off-line Enhanced Solvent Extraction (ESE)/HPLC.
Master of Science
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Ghamari, Mohsen. "An experimental examination of combustion of isolated liquid fuel droplets with polymeric and nanoparticle additives." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/5758.
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In spite of recent attention to renewable sources of energy, liquid hydrocarbon fuels are still the main source of energy for industrial and transportation systems. Manufactures and consumers are consistently looking for ways to optimize the efficiency of fuel combustion in terms of cost, emissions and consumer safety. In this regard, increasing burning rate of liquid fuels has been of special interest in both industrial and transportation systems. Recent studies have shown that adding combustible nano-particles could have promising effects on improving combustion performance of liquid fuels. Combustible nano-particles could enhance radiative and conductive heat transfer and also mixing within the droplet. Polymeric additive have also shown promising effect on improving fire safety by suppressing spreading behavior and splatter formation in case of crash scenario. Polymers are also known to have higher burning rate than regular hydrocarbon fuels. Therefore adding polymeric additive could have the potential to increase the burning rate.
In this work, combustion dynamics of liquid fuel droplets with both polymeric and nanoparticle additives is studied in normal gravity. High speed photography is employed and the effect of additive concentration on droplet burning rate, burning time, extinction and soot morphology is investigated.
Polymer added fuel was found to have a volatility controlled combustion with four distinct regimes. The first three zones are associated with combustion of base fuel while the polymer burns last and after a heating zone because of its higher boiling point. Polymer addition reduces the burning rate of the base fuel in the first zone by means of increasing viscosity and results in nucleate boiling and increased burning rates in the second and third stages. Overall, polymer addition resulted in a higher burning rate and shorter burning time in most of the scenarios. Colloidal suspensions of carbon-based nanomaterials in liquid fuels were also tested at different particle loadings. It was found that dispersing nanoparticles results in higher burning rate by means of enhanced radiative heat absorption and thermal conductivity. An optimum particle loading was found for each particle type at which the maximum burning rate was achieved. It was observed that the burning rate again starts to reduce after this optimum point most likely due to the formation of large aggregates that reduce thermal conductivity and suppress the diffusion of species.
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Sing, Charles Edward. "Photoluminescent Dye and Polymer Blends as Tunable Time-Temperature Indicators." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1220571864.
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Diar, Bakerly Bashar [Verfasser], and Josef [Akademischer Betreuer] Breu. "Innovative, Platy Nano-Additives as Efficient Flame Retardants for Polymer Nanocomposites / Bashar Diar Bakerly. Betreuer: Josef Breu." Bayreuth : Universität Bayreuth, 2016. http://d-nb.info/1093512180/34.
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Butt, Ali Azhar. "Life Cycle Assessment of Asphalt Pavements including the Feedstock Energy and Asphalt Additives." Licentiate thesis, KTH, Väg- och banteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102763.
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Roads are assets to the society and an integral component in the development of a nation’s infrastructure. To build and maintain roads; considerable amounts of materials are required which consume quite an amount of electrical and thermal energy for production, processing and laying. The resources (materials and the sources of energy) should be utilized efficiently to avoid wastes and higher costs in terms of the currency and the environment. In order to enable quantification of the potential environmental impacts due to the construction, maintenance and disposal of roads, an open life cycle assessment (LCA) framework for asphalt pavements was developed. Emphasis was given on the calculation and allocation of energy used for the binder and the additives. Asphalt mixtures properties can be enhanced against rutting and cracking by modifying the binder with additives. Even though the immediate benefits of using additives such as polymers and waxes to modify the binder properties are rather well documented, the effects of such modification over the lifetime of a road are seldom considered. A method for calculating energy allocation in additives was suggested. The different choices regarding both the framework design and the case specific system boundaries were done in cooperation with the asphalt industry and the construction companies in order to increase the relevance and the quality of the assessment. Case-studies were performed to demonstrate the use of the LCA framework. The suggested LCA framework was demonstrated in a limited case study (A) of a typical Swedish asphalt pavement. Sensitivity analyses were also done to show the effect and the importance of the transport distances and the use of efficiently produced electricity mix. It was concluded that the asphalt production and materials transportation were the two most energy consuming processes that also emit the most GreenHouse Gases (GHG’s). The GHG’s, however, are largely depending on the fuel type and the electricity mix. It was also concluded that when progressing from LCA to its corresponding life cycle cost (LCC) the feedstock energy of the binder becomes highly relevant as the cost of the binder will be reflected in its alternative value as fuel. LCA studies can help to develop the long term perspective, linking performance to minimizing the overall energy consumption, use of resources and emissions. To demonstrate this, the newly developed open LCA framework was used for an unmodified and polymer modified asphalt pavement (Case study B). It was shown how polymer modification for improved performance affects the energy consumption and emissions during the life cycle of a road. From the case study (C) it was concluded that using bitumen with self-healing capacity can lead to a significant reduction in the GHG emissions and the energy usage. Furthermore, it was concluded that better understanding of the binder would lead to better optimized pavement design and thereby to reduced energy consumption and emissions. Production energy limits for the wax and polymer were determined which can assist the additives manufacturers to modify their production procedures and help road authorities in setting ‘green’ limits to get a real benefit from the additives over the lifetime of a road.QC 20120926
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Andersson, Jonas. "Synthesis of polycarbonate polymer electrolytes for lithium ion batteries and study of additives to raise the ionic conductivity." Thesis, Uppsala universitet, Strukturkemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-259513.
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Polymer electrolyte films based on poly(trimethylene carbonate) (PTMC) mixed with LiTFSI salt in different compositions were synthesized and investigated as electrolytes for lithium ion batteries, where the ionic conductivity is the most interesting material property. Electrochemical impedance spectroscopy (EIS) and DSC were used to measure the ionic conductivity and thermal properties, respectively. Additionally, FTIR and Raman spectroscopy were used to examine ion coordination in the material. Additives of nanosized TiO2 and powders of superionically conducting Li1.3Al0.3Ti1.7(PO4)3 were investigated as enhancers of ionic conductivity, but no positive effect could be shown. The most conductive composition was found at a [Li+]:[carbonate] ratio of 1, corresponding to a salt concentration of 74 percent by weight, which showed an ionic conductivity of 2.0 × 10–6 S cm–1 at 25 °C and 2.2 × 10–5 S cm–1 at 60 °C, whereas for even larger salt concentrations, the mechanical durability of the polymeric material was dramatically reduced, preventing use as a solid electrolyte material. Macroscopic salt crystallization was also observed for these concentrations. Ion coordination to carbonyls on the polymer chain was examined for high salt content compositions with FTIR spectroscopy, where it was found to be relatively similar between the samples, possibly indicating saturation. Moveover, with FTIR, the ion-pairing was found to increase with salt concentration. The ionic conductivity was found to be markedly lower after 7 weeks of aging of the materials with highest salt concentrations.
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Seddon, Richard. "Influence of flame retardant additives on the processing characteristics and physical properties of ABS." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/14228.
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Antimony trioxide (Sb203) and halogenated additives are used together in flameretarded formulations due to their synergistic retardant properties. A study has been made to determine the effects of adding different grades of Sb203 (dSD particle sizes 0.11 um, 0.52um and 1.31 um) into ABS polymer either alone or with commercial brominated materials (BTBPE, TBBA, DBDPO) and an experimental bromine grade (sDBDPO). The Sb20 3 was added at 4wt% loadings and the bromines at 20wt% loadings. The results consider the influence of the additives on processing, mechanical, morphological and flame retardant properties. All compounds were produced using a twin-screw co-rotating extruder and then an injection moulder was used to mould notched impact (falling weight testing), flexural, LOI and UL-94 flame test bars. Samples of all the compounded formulations were titrated to determine Sb20 3 and Br contents. Fracture surface, morphology, size and dispersion analysis was carried out using both SEM and TEM equipment. Osmium tetroxide (OS04) staining was used to determine relative locations of filler particles and polybutadiene phase. Additions of the different antimony trioxide grades showed that the 0.52um and 1.31 um grades lowered impact energy absorption (-25 to -30%) when added at 4wt% loading. The use of a sub-micron size grade (0.1 um) did not significantly lower impact properties (-3%) and had similarly small effects on the flexural modulus and flexural strength. Additions of the brominated materials had much greater effects causing large reductions in impact properties (-20 to :70%). The presence of the bromines generally increased flexural modulus and lowered flexural strength with the exception of TB BA, which increased both modulus and strength. Compounds containing both 1.31 um Sb203 and bromines suffered a further reduction in impact energies, with the bromine properties dominating. Using the 0.1 um Sb20 3 grade again improved impact and flexural properties compared to the 1.31 um grade. The 0.1 um grade resulted in improvements in fire resistance as measured by the UL-94 properties when used with all bromine grades.
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Bouscher, Robert F. "Advancements in Powder Coating Processing and in Real-time Film Formation Analysis of Thermoset Coatings." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627566578541715.
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Fan, Jui Chin. "The Impact of Nanostructured Templates and Additives on the Performance of Si Electrodes and Solid Polymer Electrolytes for Advanced Battery Applications." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7568.
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The primary objectives of this research are: (1) use a hierarchical structure to study electrode materials for next-generation lithium-ion batteries (LIBs) and (2) understand the fundamentals and utility of solid polymer electrolytes (SPEs) with the addition of halloysite nanotubes (HNTs) for battery applications. Understanding the fundamental principles of electrode and electrolyte materials allows for the development of high-performance LIBs. The contributions of this dissertation are described below. Encapsulated Si-VACNT Electrodes. Two hurdles prevent Si-based electrodes from mass production. First, bulk Si undergoes volume expansion up to 300%. Second, a solid-electrolyte interphase (SEI) forms between the interface of the electrolyte and electrode, which consumes battery capacity and creates more resistance at the interface. Si volume changes were overcome by depositing silicon on vertically-aligned carbon nanotubes (VACNTs). Encapsulating the entire Si-VACNT electrode surface with carbon was used to mitigate SEI formation. Although SEI formation was reduced by the encapsulation layer, capacity fade was still observed for encapsulated electrodes, indicating that SEI formation was not the primary factor affecting capacity fade. Additionally, the impact of the encapsulation layer on Li transport was examined. Two different transport directions and length scales were relevant””(1) radial transport of Li in/out of each Si-coated nanotube (~40 nm diameter) and (2) Li transport along the length of the nanotubes (~10 µm height). Experimental results indicated that the height of the Si-VACNT electrodes did not limit Li transport, even though that height was orders of magnitude greater than the diameter of the tubes. Simulation and experimental data indicated that time constant for Li diffusion into silicon was slow, even though the diffusion distance was short relative to the tube height. Other factors such as diffusion-induced stress likely had a significant impact on diffusion through the thin silicon layer. Solid Polymer Electrolytes. A thorough understanding of the relationships between physical, transport, and electrochemical properties was studied. HNT addition to polyethylene oxide (PEO) electrolytes not only improved the physical properties, such as reduction of the crystallinity of PEO, but also enhanced transport properties like the salt diffusivity. The processing steps were important for achieving enhanced properties. Moreover, HNTs were found to stabilize the interfacial properties of the SPE films during cycling. Specifically, HNT-containing SPE films were successfully cycled at room temperature, which may have important implications for SPE-based batteries.
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Javaid, Salman. "Some aspects of ionic liquid blends and additives influencing bulk conductivity of commercial base paper." Thesis, Karlstads universitet, Avdelningen för kemiteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26775.
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In this study, bulk conductivity of commercial base paper impregnated with different ionic liquids blends and additives, through bench coating was investigated. Bulk conductivity of base paper, ion conductive paper and surface sized ion conductive papers with and without the influence of calendering were evaluated at different concentrations of ionic liquids using at resistivity cell and four point probe technique. It was shown that bulk conductivity of base paper was increased by increasing the amount of ionic liquids. Nano fibril cellulose also showed positive influence on the bulk conductivity of coated papers. By increasing the line load in the calendering machine, a positive influence on the bulk conductivity was observed. The tensile index of all the coated papers was lower than that of the base paper.
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Si, Kun. "Kinetics and Mechanism of Vinyl Chloride Polymerization: Effects of Additives on Polymerization Rate, Molecular Weight and Defect Concentration in the Polymer." online version, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1168382967.
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Bartsch, Nastasia [Verfasser]. "Polymer additives, contaminants and non-intentionally added substances in consumer products: Combined migration, permeation and toxicity analyses in skin / Nastasia Bartsch." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1177152770/34.
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