Dissertations / Theses on the topic 'Polypropylene liner'

An in-line process rheometer, employing a proven shear-stress transducer, was designed and built for polymer melts. The entire process stream runs through the rheometer, giving it a much faster response time than conventional side-stream models. The possibility of using the in-line rheometer for dynamic mechanical analysis was investigated and methods were developed to obtain the complex modulus over a wide range of frequencies with a single measurement. Measurement techniques for shear viscosity testing were also developed along with algorithms to compensate for the effects of process pressure and temperature.<br>The rheometer was used as a viscosity sensor to provide feedback control for a polypropylene visbreaking process. A first order plus dead time model was used to model the process and the rheometer together, and typically had dead times of less than 60 s and a first order time constant of 15 s. Gain scheduling was incorporated into minimum variance and proportional-integral controllers to achieve closed-loop settling times of 200 s for viscosity setpoint changes and process disturbances.

Os polímeros espumados são materiais do futuro, com um leque abrangente de aplicações. Podem ser usados em estruturas de isolamento, por exemplo, ou para reduzir custos com materiais. Este trabalho remete para a extrusão de misturas de Polipropileno isotático (iPP) / Polipropileno com Alta Resistência do Fundido (HMSPP), para a obtenção de espumas. O comportamento reológico do polímero fundido, principalmente a viscosidade na temperatura de processamento, tem um papel decisivo nas aplicações nas quais prevalece o fluxo extensional, como no caso da espumagem. Se a viscosidade for muito baixa, correspondente a uma baixa resistência do fundido, como no caso do homopolímero linear (PP isotático), a espumagem ficará prejudicada, face à impossibilidade de expansão acentuada. Entretanto, se a viscosidade for muito alta (HMSPP), com uma alta resistência do fundido, a espuma colapsará imediatamente após sua formação. A fim de obter espumas com uma estrutura celular homogênea e definida, foram efetuadas misturas 50% em peso entre o homopolímero linear (PP isotático) e o polipropileno ramificado (HMSPP), modificado por radiação gama, em ambiente contendo acetileno e na dose de 12,5 kGy. O processo de extrusão empregou a metodologia de espumagem solúvel, segundo o princípio de processamento/dissolução, que envolve a dissolução de um agente físico de sopro (PBA = Physical Blowing Agent), na pressão em torno de 30 bar, homogeneamente misturado com o fundido polimérico. As condições de extrusão, que, geralmente, compreendem o controle de temperatura, pressão e fluxo do material viscoelástico, foram investigadas experimentalmente para definir as características dominantes em prol da obtenção de espumas. O agente físico de sopro usado foi o nitrogênio. As principais características do PP e HMSPP foram obtidas via medidas reológicas (Índice de Fluidez e Resistência do Fundido) e análises térmicas (DSC/TGA), a fim de viabilizar e reproduzir a posteriori as espumagens pelo processo de extrusão. A morfologia celular das espumas foi investigada minuciosamente, com e sem a adição de talco, como agente nucleante, usando o Microscópio Eletrônico de Varredura. As propriedades mecânicas foram investigadas, via DMA, com base no Módulo de Young e tangente delta. A Rigidez Específica contribuiu com algumas considerações sobre a cristalinidade. As micrografias obtidas apontaram para espumas de células fechadas, nas quais a pressão é mantida durante o estágio de formação da célula. As espumas podem ser usadas em: mobílias; transporte; aterro sanitário; isolamentos; eletrodomésticos; como absorvedora de choque e de som; construção civil, incluindo chapas isolantes, proteção para pisos, perfis para acabamento, acabamentos de interiores; indústria automobilística, em painéis espumados; mercado de embalagem, em geral, incluindo embalagens para freezer e micro-ondas; acondicionamento de artigos médicos como seringas, catéteres intravenosos, frascos, materiais de sutura. fios e cabos e para finalidades estruturais (espumas estruturais), substituindo madeira, metais ou plásticos sólidos. As análises de densidade efetuadas nas espumas do presente trabalho apresentaram resultados típicos de espumas de alta densidade (faixa de 320 a 800 kg/m3), em torno de 500 kg/m3, usadas para fios e cabos e para finalidades estruturais (espumas estruturais), substituindo madeira, metais ou plásticos sólidos. As espumas estruturais têm densidades relativamente altas (acima de 320 kg/m3) e as estruturas celulares são compostas principalmente de vazios.<br>Foamed polymers are future materials, with a comprehensive application field. They can be used in order to improve appearance of insulation structures, for example, or to reduce costs involving materials. This work address to Isotactic Polypropylene / High Melt Strength Polypropylene blends, for foams production. Rheological behavior of polymer melt, especially referring to viscosity in processing temperature, plays a decisive role in applications where dominates extensional flow, as in case of foaming. If the viscosity is very low, it will correspond to a low melt strength, as in case of linear homopolymer (Isotact PP), and the foam will be prejudiced, due to the impossibility of expansion. Otherwise, if the viscosity is very high, with a high melt strength, the foam will collapse immediately after its formation. In order to get foams with an homogeneous and defined cellular structure, there were accomplished blends, 50% in weight, between linear homopolymer (isotactic PP) and HMSPP, from PP modified as per gamma radiation, in acetylene environment and at a 12.5 kGy dosis. Extrusion process used a soluble foaming methodology, according to a processing/dissolution principle, which involves the dissolution of a Physical Blowing Agent (PBA), under 30 bar pressure, homogeneously mixed with polymeric melt. Extrusion conditions, that generally involve temperature, pressure and viscoelastic material flow control were experimentally investigated to define prevalent characteristics for producing foams. Nitrogen was the used PBA and process extrusion parameters were adapted to PP, HMSPP and their 50% in weight mixtures thereof. Major PP and HMSPP characteristics were obtained via melt Index and melt strength and thermal analyses (DSC/TGA), in order to make viable and to reproduce foaming as per extrusion process. Foams cellular morphology of PP, HMSPP and their 50% in weight mixtures thereof was investigated, with and without talc addition, as nucleating agent, by using Scanning Electron Microscope (SEM). Micrographs obtained pointed to closed cells foams, in which the pressure is kept during all cell formation stage, informing that closed cells foams are used in thermal insulation in Civil Construction and in thermal vials. Density analyses accomplished in foams produced in our work showed typical results for high density foams (320 to 800 kg/m3 range), around 500 kg/m3, used for wire and cables and for structural purposes (structural foams), by replacing wood, metals or solid plastics. Structural foams have high density (above 320 kg/m3) and cellular structures are specially composed by holes.

The potential use of Resadiye/Tokat bentonite as a reinforcement in polypropylene (PP) and linear low density polyethylene (LLDPE) polymer matrix nanocomposites filler was investigated. At first, organoclays (OC) were prepared by cation exchange reaction (CER) between the raw bentonite (RB) and three quaternary ammonium salts with long alkyl tails (QA): hexadecyl trimethyl ammonium bromide [HMA] [Br], tetrabutyl ammonium tetrafluoroborate [TBA] [BF4], tetrakisdecyl ammonium bromide [TKA] [Br] and one quaternary phosphonium (QP) salt: tetrabutyl phosphonium tetrafluroborate [TBP] [BF4]. Characterization of resulting materials by XRD, TGA, FTIR and chemical analysis confirmed the formation of organoclays. Ternary composites of PP/organoclay/ maleic anhydride grafted polypropylene (MAPP) were prepared with two different grades of PPs in a co-rotating twin screw extruder. Composites prepared with these organoclays and PPs showed microcomposite formation. In the second part of the study, raw bentonite was purified by sedimentation, and characterization of purified bentonite (PB) by XRD, cation exchange capacity (CEC) measurement and chemical analysis (ICP) confirmed the success of purification method. PB was then modified with two QA`s: dimethyl dioctadecylammonium chloride [DMDA] [Cl], tetrakis decylammonium bromide [STKA] [Br] and one QP: tributyl hexadecyl phosphonium bromide [TBHP] [Br]. Organoclays from PB were used with the PP with lower viscosity, and ternary nanocomposites (PP/Organoclay2/MAPP5) were prepared in the extruder followed by batch mixing in an intensive batch mixer. Use of DMDA and TBHP OCs resulted in nanocomposite formation, while STKA resulted in microcomposite formation as observed by XRD and TEM. Young`s modulus and yield stress of the samples were enhanced through nanocomposite formation. In the last part of the study, ternary composites of LLDPE/Organoclay/ compatibilizer, a random terpolymer of ethylene, butyl acrylate and maleic anhydride (E-BA-MAH, Lotader&reg<br>3210), were prepared by melt compounding in the batch mixer at two different clay concentrations (2 and 5 wt %) and fixed compatibilizer/organoclay ratio (&alpha<br>=2.5). A commercial organoclay, I34, was also used in LLDPE based nanocomposites to make a comparison. XRD and TEM analyses of the compounds prepared by DMDA and TBHP showed mixed nanocomposite morphologies consisting of partially intercalated and exfoliated layers. Young`s modulus and tensile strength of nanocomposites prepared with DMDA and TBHP showed generally higher values compared to those of neat LLDPE, while results were the highest in the composites prepared with commercial organoclay I34. Parallel disk rheometry was used as a supplementary technique to XRD, TEM and mechanical characterizations, and it was shown to be a sensitive tool in assessing the degree of dispersion of clay layers in the polymer matrix.

Made available in DSpace on 2014-10-09T12:27:13Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T13:57:01Z (GMT). No. of bitstreams: 0<br>Dissertacao (Mestrado)<br>IPEN/D<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

L'industrie petrochimique nigerianne que nous avons propose d'analyser presente un certain nombre de specificites, lesquelles ont justement motive notre recherche. La saisie de la principale de ces specificites a ete effectuee en analysant l'existence d'un secteur petrochimique dans le cadre du developpement d'un secteur petrochimique dans le cadre du developpement d'ensemble du nigeria a travers la theorie des "industries motrices". Mais on montre en meme temps que l'analyse de developpement historique du nigeria fait apparaitre les limites des conditions de pertinence de cette theorie. - dans le cadre de l'industrie petrochimique elle-meme, le con- cept central du "calcul des effets d'entrainements" s'applique loique- ment. - dans le cadre du developpement global, la theorie des "industries motrices" rencontre beaucoup de reserves quant a son appli- cation en tant que methodologie, dans la mesure meme ou l'autre concept principal de cette theorie. Celui de la "triangulation", n'a pas son correspondant objectif dans la strategie des pouvoirs publics nigerians. Certes, le nigeria n'a pas suivi cette voie; mais pas seu- lement parce qu'il n'avait pas de societe civile moderne, mais aussi parce que la classe politique n'etait pas soudee et parce qu'elle n'etait pas predisposee a rompre avec les flux classiques des relations internationales<br>The petrochemical instrutory of nigeria that we propose to analyse poresents certain number of specificitises which indeed motivated our research. The apprehension of these principal specificities were observed by analysing the existence of a section of petrochemical industry in the context of general development of nigeria through the theory of "inductible industries" (industrie motrices). But at the same time our studies reveals through its analysis that the historical development of nigeria presents limits of pertinents condition of this theory. Withen petrochemical industry itself, the major concept of calculation * of linkage and induction effect show corresponding application. * on the level of general development of nigeria, the concept of "inductibility" or "linkage" industires meet lots of handicorp in its methodological application, in the sense that the other other concept of the theory : that of "triangulation" does not have its objective correspondance in the strategic planing, by nigerian decision makers. Thus nigeria did not opte for this concept as to it's development, not for the fact that it does not have a modern administrative society, nor was it for the fact it's decision. .

A novel on-line capillary rheometer (OLR) was used to examine the shear and extensional characteristics of polyolefin melts during twin screw extrusion (TSE). Comparisons with off-line rheometry were made using a twin-bore capillary rheometer and a modular in-line slit die rheometer (ILR) provided in-line rheometry comparisons. Both capillary rheometers were controlled via PCs running dedicated software, and the extrusion line and ELR were fully instrumented allowing real-time process monitoring to be carried out by IBM compatible PCs via data acquisition hardware and software. The prototype OLR was developed by the re-design of several key features including an instrumented transfer section and capillary die block which facilitated the use of various die geometries. Shear and extensional on-line rheometry of three polyethylenes (linear and branched), and four molecular weight grades of polypropylene were examined, and a direct comparison with off-line capillary rheometry showed a good correlation. The effect of a high loading of filler on two of the polyethylenes was investigated. In-line shear stress and entry pressure measurements showed a reasonable correlation with on-line rheometry. A study of entry flows in the OLR using capillary dies approaching orifice showed non-linearities occurred at very low capillary length to diameter(L:D) ratios, and this was repeatable using off-line rheometry. Predicted zero length entry pressures (Po) were used to estimate apparent extensional viscosity using a number of standard models. Melt instability and capillary wall slip were also investigated using on-line rheometry. Melt pressure and temperature in the twin screw extruder and OLR were monitored at various process conditions to examine the ability of the OLR to condition melt during testing, and the effect of OLR testing on extrusion conditions. Pressure variation in the extruder, OLR and off-line rheometer were compared in order to quantify process noise. The effect of OLR testing on melt rheology and polymer molecular weight were examined using off-line rheometry and gel permeation chromatography(GPC).

Made available in DSpace on 2016-06-02T19:10:21Z (GMT). No. of bitstreams: 1 5915.pdf: 3044014 bytes, checksum: 6a376f2e7b858f324320d8e103c124a2 (MD5) Previous issue date: 2014-04-17<br>Universidade Federal de Sao Carlos<br>The grafting reaction of maleic anhydride onto polypropylene by reactive extrusion, in presence of nanoclay, was studied. The organoclay (Cloisite 20A) was used as support for dicumyl peroxide (DCP), and different amounts of clay were used. The increment in the clay amount leads to reduction in the reaction rates, because it hinders the peroxide release, once organoclay absorbs partially the peroxide. Changes in the reaction mechanisms, in presence and absence of clay, were performed in a Haake internal mixing chamber, between 1 and 7 min of reaction. The results showed changes in the number, and length of maleic anhydride grafting, and in the molar mass. The reactive extrusion of polypropylene with maleic anhydride was studied based in central composite experimental design, using as factors the maleic anhydride and dicumyl peroxide concentrations. The experimental design was analyzed by ANOVA and shows that the increment in clay, used as peroxide support, leads to decrease in the grafting reaction of short succinic groups, by the introduction of long succinic groups, because its concentration increases the maleic anhydride homopolymerization. In the same way the increase in maleic anhydride concentration leads to decrease in the PP grafting level, because the maleic anhydride homopolimerization is increased, decreasing the reaction between polymer and monomer. The in-line monitoring of the reactive extrusion showed a good correlation between the light absorption measured and the formation of secondary reaction products, lately identified off-line as poli(maleic anhydride).<br>Neste trabalho estudou-se a reação de graftização de anidrido maleico em polipropileno, por extrusão reativa, na presença de nanopartículas argila montmorilonita. A argila montmorilonita organicamente modificada (Cloisite 20A) foi utilizada como suporte para o peróxido de dicumila (DCP), e foi testada em diferentes proporções. Este estudo mostrou que a argila é capaz de absorver parcialmente o peróxido, e que a quantidade de peróxido absorvida interfere no rendimento das reações. As alterações no mecanismo de reação, induzidas pela presença de argila, foram inicialmente estudadas em câmara de mistura Haake, sendo que a reação, na presença e ausência da argila, foi realizada entre 1 e 7min. Os resultados indicam alterações no tamanho e número de enxertias, além de alterações na degradação das cadeias poliméricas, estudadas através de SEC. Já a extrusão reativa do polipropileno com anidrido maleico, foi estudada com base em um planejamento experimental tipo composto central, onde os fatores estudados foram as concentrações de anidrido maleico e peróxido. A análise do planejamento experimental, realizada por ANOVA, mostra que a presença da argila, utilizada como suporte para o peróxido, tende a diminuir a quantidade de enxertias succínicas curtas, favorecendo a inserção de enxertias succínicas longas, devido à maior incidência das reações de homopolimerização do anidrido maleico. De maneira análoga o aumento nas concentrações de anidrido maleico, diminui o nível de reação, pois há maior concorrência entre as reações de graftização e homopolimerização do monômero. O monitoramento em tempo real das extrusões, mostrou a possibilidade de quantificação da modificação química por meio de colorimetria in-line, através do monitoramento da formação de produtos secundários, identificados como poli(anidrido maleico).

L’objectif de cette thèse a été d’étudier un traitement de surface innovant basé sur un contact avec un mélange réactionnel gazeux F2/O2. (oxyfluoration) déjà utilisé industriellement sur polymères mais sans application jusqu’à présent au niveau des fibres naturelles. Ces travaux se sont inscrits dans le cadre d’un projet collaboratif ayant pour objectif d’étudier et de développer les applications industrielles de ce traitement sur des fibres naturelles d’origines végétales (coton, lin) et animales (laine et soie). Le but a été d’intégrer principalement des fonctions oxygénées. La compréhension des mécanismes en jeu a été réalisé via la combinaison de plusieurs techniques d’analyse de surface, parmi lesquelles les techniques de microscopie (MEB, AFM) et les techniques spectroscopiques (XPS, ToF-SIMS). Grâce à la complémentarité de ces différentes techniques d’analyses il est apparu que le traitement d’oxyfluoration ne dégrade pas la surface et introduit en surface une quantité significative d’oxygène peu dépendante de la composition initiale du support mais avec des fonctions chimiques par contre variables selon la structure chimique initiale. Les résultats obtenus, notamment lors de tests de stabilité, ont montré que le fluor, également détecté en surface après le traitement, n’est pas réellement intégré dans la structure chimique des supports. La comparaison à des traitements plasmas a montré que le traitement présente moins de variabilité, ce qui a été confirmé en envisageant, via un plan d’expériences, l’ensemble des modifications possibles dans un contexte d’application industrielle. L’étude d’un transfert industriel a ensuite été mise en œuvre dans le cas du remplacement des traitements de préparation avant teinture du coton et l’efficacité a été testée en fonction des résultats des tests métiers. Le manque de variabilité du traitement n’a pas permis d’identifier de conditions suffisamment optimales pour proposer le remplacement des traitements actuels malgré les avantages d’un traitement en phase gazeuse et à pression atmosphérique<br>The objective of this thesis was to study a new surface treatment based on contact with a gaseous reaction mixture F2/O2. (oxyfluorination) already used industrially on polymers but not yet applied to natural fibres. This work was part of a collaborative project aimed at studying and developing the industrial applications of this treatment on natural fibres of vegetable (cotton, linen) and animal (wool and silk) origin. The aim was to integrate mainly oxygenated functions. The understanding of the mechanisms involved was achieved by combining several surface analysis techniques, including microscopy techniques (SEM, AFM) and spectroscopic techniques (XPS, ToF-SIMS). Thanks to the complementarity of these different analysis techniques, it appeared that the oxyfluorination treatment does not degrade the surface and introduces a significant quantity of oxygen on the surface, which is not very dependent on the initial composition of the support but with chemical functions that vary according to the initial chemical structure. The results obtained, particularly in stability tests, have shown that fluorine, also detected on the surface after treatment, is not really integrated into the chemical structure of the supports. The comparison with plasma treatments showed that the treatment has less variability, which was confirmed by considering, via a design of experiments, all the possible modifications in an industrial application context. The study of an industrial transfer was then implemented in the case of the replacement of preparation treatments before dyeing cotton and the effectiveness was tested according to the results of the business tests. The lack of treatment variability did not allow to identify sufficiently optimal conditions to propose the replacement of current treatments despite the advantages of gas phase and atmospheric pressure treatment

Ghana, a West Africa country, is deeply burdened by poverty, and relies on the production of gold for economic sustainability. The gold mining companies in the country have international origins and receive most of their requirements from international sources. The extraction of gold from the crushed ore requires sodium cyanide as a lixiviant, which is imported into Ghana from other countries in wooden intermediate bulk containers (IBC) for further distribution to the mines. A life cycle assessment was completed to determine the burden that this packaging, which includes the wooden container and polyethylene and polypropylene liners, places on the environment in Ghana when disposed of. It was found that the life cycle of the incinerated IBC impacted on the Ghanaian environment the most, due to the incineration and the transportation of the IBC. The International Organization for Standardization 14040 management standard was used as a methodological framework for the assessment.<br>Environmental Science<br>M.Sc. (Environmental Science)

No<br>The in-line development of crystalline morphology and orientation during melt extrusion of low density polyethylene (LDPE) tape at nil and low haul-off speeds has been investigated using Small-Angle X-Ray Scattering (SAXS). The processing parameters, namely haul-off speed and distance down the tape-line have been varied and the resulting crystalline morphology is described from detailed analysis of the SAXS data. Increasing haul-off speed increased orientation in the polymer tape and the resulting morphology could be described in terms of regular lamellar stacking perpendicular to the elongation direction. In contrast, under nil haul-off conditions the tape still showed some orientation down the tape-line, but a shish-kebab structure prevails. The final lamellae thickness (similar to 50 angstrom) and bulk crystallinity (similar to 20%), were low at, for all processing conditions investigated, which is attributed to the significant short-chain branching in the polymer acting as point defects limiting lamellae crystal growth. (C) 2013 Elsevier Ltd. All rights reserved.

Polypropylene (PP) and ethylene-co-octene copolymer (EOC) blends were prepared at various component ratios and reinforced with silica nanoparticles (SiO2). Strategies to improve filler dispersion involved the grafting of a silane coupling agent on the PP matrix, the addition of a maleated PP (PP-g-MA) as a compatibilizer and the use of hydrophobic silica nanoparticles. These approaches resulted in a fine dispersion of the nanoparticles within the PP phase and induced a reduction of the size of the EOC domains, due to a barrier effect. Tensile and flexural properties were significantly increased, whereas ductility and impact properties were not affected. These enhancements are attributed to the favourable microstructure of the blends, featuring a segregated microstructure, and to the improved interfacial adhesion between the functionalized polymer matrix and the surface of the nanoparticles. The microstructure and rheology of model melt compounded EOC-based nanocomposites were investigated. Functionalization of the polyolefin matrix was accomplished through silane grafting, or addition of a maleated EOC (EOC-g-MA) compatibilizer. Various grades of unmodified SiO2 having different specific surface areas (SSA), as well as a surface-modified grade were added to the EOC matrix at various loadings. The formation of covalent and hydrogen bonds between the silanol groups and the functionalized polymer generated strong polymer/filler (P/F) interactions, resulting in improved filler dispersion. Bound polymer characterization revealed that in the compatibilized materials, the amount of polymer physically attached to the nanoparticles was higher than in the non-compatibilized samples. In the absence of a compatibilizer, larger SiO2 aggregates formed upon increasing SSA because of increased probability of hydrogen bonding between the particles. The increased propensity for aggregation was revealed by time sweeps as well as by the increased strain sensitivity in stress sweeps. On the contrary, the compatibilized composites exhibited a stable response and a higher critical strain for the onset of non-linearity, indicative of stronger adhesion between the fillers and the matrix. Superposition of oscillatory and creep/recovery experiments revealed that the viscoelastic properties in the terminal region were influenced substantially by the state of dispersion of the nanoparticles. In the absence of a compatibilizer, substantial enhancements in the linear viscoelastic (LVE) functions were noted and an increasing SSA resulted in more significant deviations from terminal flow. On the contrary, the SSA of the particles had no effect on the viscoelastic and mechanical properties of the compatibilized composites.<br>Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2011-04-18 15:17:52.471

No<br>Solid phase orientation of polymers is one of the most successful routes to enhancement of polymer properties. It unlocks the potential of molecular orientation for the achievement of a range of enhanced physical properties. We provide here an overview of techniques developed in our laboratories for structuring polymers by solid phase orientation processing routes, with a particular focus on die drawing, which have allowed control of significant enhancements of a single property or combinations of properties, including Young's modulus, strength, and density. These have led to notable commercial exploitations, and examples of load bearing low density materials and shape memory materials are discussed.