To see the other types of publications on this topic, follow the link: Copolymers of ethylene vinyl acetate.
Dissertations / Theses on the topic 'Copolymers of ethylene vinyl acetate'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Copolymers of ethylene vinyl acetate.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Auden, Noel Geraint. "Ethylene-vinyl acetate copolymers." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239046.
Full text
2
Hatzinikolaou, Theodosios A. "Adhesion of ethylene vinyl acetate copolymers to metals." Thesis, University of Bath, 1985. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355114.
Full textAbstract:
The 180° peel strength of four ethylene vinyl acetate copolymers with varying V.A. content was measured (Pol A: 28%, Pol B: 18%, Pol C: 12% and Pol D: 9.5% by weight). The polymers were applied as hot-melts with or without an inextensible fabric support on: (a) mild steel etched in hydrochloric acid; (b) chemically polished copper and; (c) oxidised copper with a fibrous topography. The peel loads for a given polymer decreased from oxidised copper to etched steel to polished copper. For a given substrate the peel loads generally decreased from polymer A to polymer D with a peak for polymer C. This trend was correlated to similar trends obtained in mechanical tests like the tearing energy, strain energy density and tensile strength to failure. The fractured parts of the bond were examined with a scanning electron microscope. There was microscopic evidence of an analogy between the peel load and the observed extent of polymer deformation in the fractured surfaces where the ductilty of the particular polymer and the topography of the substrate were clearly depicted. Contact angle measurement showed a cohesive type of failure in all cases. X-ray photo-electron spectroscopy and multiple internal reflection infra-red spectroscopy provided evidence of polymer oxidation by the substrate, mostly significant in the case of etched steel. The energy balance approach was employed in order to analyse the peel test results further. The polymers response to the imposed mechanical deformations during peeling was shown to control the measured peel load. For the unbacked samples the major energy loss mechanism is the stretching of the freed strip. The much higher peel loads of the backed samples were attributed to energy losses around the peel front. Finally, plastic bending of the polymer was found to account for a relatively smaller part of the total input energy for both backed and unbacked samples.
3
Clough, Norman E. "Thermodynamics of ethylene-vinyl acetate copolymer blends." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5489/.
Full textAbstract:
The purpose of this study was to characterise the miscibility of several poly(ethylene-co-vinyl acetate), EVA, based polymer blends. EVA has many industrial applications and is often present as one of several polymeric components. Consequently, there is considerable interest in the thermodynamics of these blend systems. The thermodynamics of these blends was studied using several techniques: differential scanning calorimetry; phase contrast optical microscopy; small angle neutron scattering and wide angle X-ray scattering. Characterisation was also to include assessing the relative enthalpic and entropic thermodynamic contributions to the Rory-Huggins interaction parameter (%) of these blends. To determine the enthalpic interaction parameter, a "mixing calorimeter" was designed and constructed to measure accurately the "heat of mixing" values on blending these polymers. Free energy interaction parameters were determined from melting point depression and small angle neutron scattering measurements. In all the blends studied, the heat of mixing was endothermic and consequently, the enthalpic interaction parameters were positive i.e. unfavourable to miscibility. Miscibility in these blends can therefore only be achieved by a dominant entropic contribution, favourable to miscibility. Using phase contrast optical microscopy, both miscible and immiscible phase behaviour was observed in this series of blends. This shows good agreement with predictions of miscibility from heat of mixing, melting point and small angle neutron scattering measurements, based on the classical Flory-Huggins lattice theory. Wide angle X-ray scattering and differential scanning calorimetry results have associated miscible blends with crystallisation effects between the blend components. Small angle neutron scattering has been used to determine the concentration and temperature dependence of interaction parameters in a miscible blend. From these values the upper critical solution temperature (UCST) of the blend was predicted. The enthalpic contributions to these interaction parameters show good agreement with experimental values determined from heat of mixing measurements. It was concluded that the classical Flory-Huggins lattice theory (despite its many well documented Limitations) appears to be particularly suited to the thermodynamic characterisation of miscibility in these polymer blends.
4
Okpe, Owoicho. "Alumina trihydrate as a fire retardant for ethylene vinyl acetate copolymer." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339740.
Full text
5
Khunniteekool, Chonlada. "Structure/property relationships of cross-linked polyethylene and ethylene vinyl acetate copolymer foams." Thesis, University of Manchester, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390453.
Full text
6
Nuamthanom, Anuttra. "Multidimensional NMR studies of poly(ethylene-co-1-octene) copolymers and poly(ethylene-co-vinyl acetate-co-carbon monoxide) terpolymers." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1183614323.
Full text
7
Schofield, Wayne Christopher Edward. "Factors affecting the performance of magnesium hydroxide flame retardant fillers in an ethylene vinyl acetate copolymer." Thesis, Manchester Metropolitan University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297579.
Full text
8
Bergerbit, Cédric. "RAFT polymerization of ethylene for the synthesis of polar-apolar olefin block copolymers." Thesis, Lyon, 2019. https://n2t.net/ark:/47881/m6s181w9.
Full textAbstract:
La synthèse de copolymères à blocs, comprenant un bloc semi-cristallin de polyéthylène (PE) apolaire et un bloc polaire (poly(acétate de vinyle) (PAcV), poly(méthacrylate de méthyle) (PMAM), poly(oxide d’éthylène) (POE)) a été étudiée par polymérisation RAFT. L’étude préliminaire de l’homopolymérisation de l’éthylène en conditions relativement douces (T = 70 – 80 °C, P = 200 bar) a révélé que l’utilisation d’agents de transfert de chaîne (ATC) de type xanthates aromatiques conduit à une perte de fonctionnalité des extrémités de chaînes au cours de la polymérisation, conséquence directe de réactions de terminaison se produisant sur le radical intermédiaire. L’utilisation de dithiocarbamates aromatiques a permis de s’affranchir de ce mécanisme parasite et pour la première fois des chaînes de PE présentant une fonctionnalité de bout de chaîne proche de 100%. Des ATCs macromoléculaires polaires, obtenus avec les agents de transfert de chaînes identifiés au cours de l’étude préliminaire, ont ensuite été utilisés pour la synthèse de copolymères à blocs dans le carbonate de diméthyle (DMC), un solvant organique peu transférant. Le rôle clé de la thermodynamique du milieu de polymérisation (mélange DMC/éthylène supercritique à 200 bar) a alors été mis en évidence. En effet, les macro-ATCs sont insolubles dans un tel milieu, ce qui a conduit à la formation d’un mélange d’homopolymères. La diminution de la pression de polymérisation (P < 100 bar) a toutefois permis d’éviter ce phénomène et les copolymères PVAc-b-PE, PMMA-b-PE et PEO-b-PE attendus ont été obtenus. Des propriétés d’auto-assemblage ont été mises en évidence et des morphologies de type fibre ont été obtenues pour les copolymères PMMA-b-PE et PEO-b-PE synthétisés dans le DMC, permettant d’envisager un mécanisme de type auto-assemblage induit par la polymérisation (PISA). Le passage en milieu aqueux en utilisant le macro-ATC hydrosoluble PEO a permis l’observation de morphologies de type sphériques, vésicules ou encore ellipsoïdes selon le rapport molaire macro-ATC/amorceur utiliséThe synthesis of polar-apolar olefin block copolymers, combining a semi-crystalline polyethylene (PE) block and a polar block (poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO)) was investigated by RAFT polymerization. A preliminary study on ethylene homopolymerization revealed parasite cross-termination reactions happening at the intermediate radical, resulting in the loss of chain-end fidelity when using aromatic xanthates as chain transfer agents (CTA) under relative mild conditions (T = 70 – 80 °C, P = 200 bar). The extent of cross-termination was greatly reduced with aromatic dithiocarbamates, and for the first time, PE chains with a high livingness were obtained. These first results were used to equip polar macromolecular CTAs (PVAc, PMMA, PEO), with selected aromatic xanthates and dithiocarbamates, that were further used for block copolymerization with ethylene in a low-transferring organic solvent (dimethyl carbonate, DMC). A critical influence of the ethylene pressure was evidenced as block polymerization at 200 bar could not be achieved due to solubility issues in the resulting supercritical DMC/ethylene mixture. This was circumvented by performing the block copolymerization below the supercritical point of the mixture (P < 100 bar) and well-defined PVAc-b-PE, PMMA-b-PE and PEO-b-PE copolymers were eventually obtained. The block copolymers were found to feature self-assembly properties and worm-like morphologies were observed for PMMA-b-PE and PEO-b-PE synthesized in DMC, hinting at a plausible polymerization-induced self-assembly (PISA) mechanism. The successful switch from DMC to water for the synthesis of PEO-b-PE copolymers enabled the observation of various particle morphologies: spheres, vesicles and ellipsoidal particles, depending on the initial macro-CTA:initiator molar ratio
9
Rodriguez-Vazquez, Miguel. "Thermal and photo degradation and stabilisation of an ethylene vinyl acetate copolymer in the presence of air." Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289615.
Full text
10
Alencar, Ana Ellen Valentim de. "Estudo das propriedades do cimento asfÃltico de petrÃleo modificado por copolÃmero de etileno e acetato de vinila(eva)." Universidade Federal do CearÃ, 2005. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1439.
Full textAbstract:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorCimento AsfÃltico de PetrÃleo (CAP), caracterizado como CAP 50/60, oriundo do Campo Fazenda Alegre, no estado do EspÃrito Santo, foi modificado por adiÃÃo de CopolÃmero de Etileno e Acetato de Vinila (EVA). Na modificaÃÃo foram incorporadas amostras do copolÃmero EVA puro e proveniente do resÃduo da indÃstria de calÃados (EVAR). Os CAPS, polÃmeros e CAPS modificados, foram inicialmente caracterizados por espectroscopia no infravermelho (FTIR) e ressonÃncia magnÃtica nuclear (RMN). AnÃlise tÃrmica, como a termogravimetria (TG) e caloria exploratÃria diferencial (DSC), foi utilizada para o estudo da decomposiÃÃo tÃrmica, bem como para avaliar a estabilidade termoxidativa das amostras. Testes empÃricos como penetraÃÃo, ponto de amolecimento, susceptibilidade tÃrmica e retorno elÃstico, alÃm de viscosidade, tambÃm foram realizados para caracterizaÃÃo dos materiais. Os resultados indicaram que CAPS modificados apresentaram maior estabilidade em atmosfera oxidativa do que em atmosfera inerte. A anÃlise das curvas DSC revelou que os CAPS modificados mostraram-se mais resistentes à trincas tÃrmicas, quando submetidos a temperaturas mais baixas, que o CAP convencional. Os CAPS modificados foram mais resistentes à decomposiÃÃo oxidativa, quando foram submetidos ao envelhecimento simulado. A viscosidade do ligante modificado por adiÃÃo do polÃmero foi aumentada em relaÃÃo ao ligante puro. Diferentemente do CAP convencional, o CAP modificado por EVAR apresentou comportamento nÃo Newtoniano. Os ensaios empÃricos, relativos à penetraÃÃo, ponto de amolecimento, susceptibilidade tÃrmica e retorno elÃstico, mostraram que os CAPS modificados com EVAR, tiveram uma melhoria nas suas propriedades fÃsicas, em relaÃÃo aos CAPS nÃo modificados.
The Petroleum Asphaltic Cement characterized as CAP 50/60, produced at the state of EspÃrito Santo (Fazenda Alegre), was modified by addition of copolymers of ethylene vinyl acetate (EVA) and EVA from the footwearâs industry residue (EVAR). The original and modified CAPS were characterized by infrared spectroscopy (FTIR) and nuclear magnetic resonance (RMN). Thermal analysis,as thermogravimetry (TG) and differential scanning calorimetry (DSC), was used to evaluate the thermal stability of the samples. The characterization was also performed with empirical tests such as penetration, softening point, elastic recovery and viscosity. The main results indicated that polymer modified CAPS presented larger thermal stability in oxidative atmosphere than in inert atmosphere. The analysis of DSC curves revealed that modified CAPS, when submitted to lower temperatures, were more resistant to the thermal cracks than conventional CAP. Also modified CAPS showed to be more resistant to the thermal oxidative decomposition, when submitted to a simulated aging process. The viscosity of the polymer modified binder was increased in relation to the original binder. Polymer modified CAP EVAR presented non-Newtonian behavior, whereas Newtonian behavior was observed for unmodified CAP. It was observed that modifying the asphalt binder with a copolymer EVAR leads to an improvement in the physical properties in relation to the penetration, softening point, thermal susceptibility and elastic recovery
11
Intharapat, Punyanich. "Thermoplastic natural rubbers based on natural rubber (NR) and ethylene vinyl acetate copolymer (EVA) with natural rubber-graft- poly(dimethyl(methacryloyloxymethyl)phosphonate) (NR-g-PDMMMP) as compatibilizer." Le Mans, 2009. http://cyberdoc.univ-lemans.fr/theses/2009/2009LEMA1005.pdf.
Full textAbstract:
Des copolymères greffés à base de caoutchouc naturel (NR) et de poly(acryloyloxyméthylphosphonate de diméthyle) (NR-g-PDMAMP), de poly(méthacryloyloxyéthylphosphonate de diméthyle) (NR-g-PDMMEP) et de poly(méthacryloyloxyméthylphosphonate de diméthyle) (NR-gPDMMMP), ont été synthétisés en milieu latex selon la méthode dite « grafting from » à partir de sites amorceurs photosensibles N ,Ndiéthyldithiocarbamate préalablement introduits le long des chaînes 1,4-polyisoprène du caoutchouc naturel. Des études de compatibilisation des mélanges caoutchouc naturel (NR) / copolymère d'éthylène - acétate de vinyle (EV A) ont par la suite été envisagées avec le copolymère NR-gPDMMMP, choisi comme agent compatibilisant. Elles ont été effectuées sur des mélanges simples 50/50 NR/EV A, mais aussi des mélanges dynamiquement vulcanisés 40/60 NR/EVA. Dans les deux cas,les influences du taux de greffage du NR-g-PDMMMP (71, 80, 89, et 95%) et du taux de chargement en compatibilisant (0, 1,3,5,7,9,12, et 15 % en poids par rapport au NR) sur les propriétés rhéologiques, dynamiques, mécaniques, morphologiques, et thermiques, ont été étudiées. Les meilleurs effets de compatibilisation ont été observées avec un copolymère NR-g-PDMMMP ayant un taux de greffage de 80 %, pour un taux de chargement de 7 % dans le cas du mélange simple 50/50 NR/EV A et de 9 % dans celui du mélange dynamiquement vulcanisé 40/60 NR/EV A. Les études microscopiques par SEM des mélanges ont montré une réduction de la taille des domaines. Il a aussi été noté que la stabilité thermique du mélange NR/EVA se trouve renforcée avec l'incorporation du NR-g-PDMMMPGraft copolymers of natural rubber and poly(dimethyl(acryloyloxymethyl)phosphonate) (NR-g-PDMAMP), natural rubber and poly(dimethyl(methacryloyloxyethyl)phosphonate) (NR-g-PDMMEP), and natural rubber and poly(dimethyl(methacryloyloxymethyl)phosphonate) (NR-g-PDMMMP), were prepared in latex medium via a "grafting from" methodology based on the photopolymerization of vinyl monomers initiated from N,N-diethyldithiocarbamate groups previously bound in side position of the 1,4-polyisoprene chains of natural rubber. Thereafter, compatibilization studies of natural rubber (NR) / ethylene vinyl acetate copolymer (EV A) blends were considered using NR-g-PDMMMP as a blend compatibilizer. The investigations were carried out on two categories of blends : uncured 50/50 and dynamically cured 40/60 NR/EV A blends. Ln the two cases, the influences of NR-g-PDMMMP grafting rates (i. E. , 71, 80, 89, and 95 %) and of loading level in compatibilizer (i. E. , 0, 1,3,5,7,9,12, and 15 wt% compared to NR) on rheological, dynamical, mechanical, morphological, and thermal properties, were studied. The best compatibilization effects were observed with a NR-g-PDMMMP having a grafting rate equal to 80 %, at a loading level of 7 wt% for 50/50 uncured blend and 9 wt% for 40/60 dynamically cured blend. In these conditions, the highest complex viscosity (positive deviation), tensile strength, and elongation at break, as well as the lowest values of tension set and tan d (damping factor), were observed. SEM micrographs of compatibilized blends showed a size decrease of the domains. It was also noted that the thermal stability of NR/EV A blends was improved by incorporating NR-g-PDMMMP
12
Zarrouki, Arthur. "Synthèse de polymères à base d'éthylène pour additiver les carburants." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1039.
Full textAbstract:
Les gazoles, carburant automobile préféré des français, sont « additivés » afin de permettre leur utilisation en hiver. Les n-paraffines présentes dans ces gazoles cristallisent en effet à basse température. Ces cristaux peuvent alors entraîner le colmatage des filtres protecteurs situés en amont du moteur. Des polymères à base d'éthylène, notamment les copolymères éthylène-acétate de vinyle (EVA), sont utilisés pour abaisser la température à laquelle les problématiques de filtration adviennent. Un nouveau procédé de copolymérisation radicalaire d'éthylène et d'acétate de vinyle, à plus basse pression et à plus basse température, que le procédé industriel actuel, a été développé au cours de cette thèse. Une grande variété d'EVA a ainsi été obtenue. Ils présentent des caractéristiques structurelles et une efficacité, pour le traitement des gazoles, similaires aux EVA commerciaux. Ce procédé a, par ailleurs, permis la synthèse d'autres co- et terpolymères de l'éthylène variant par la nature des comonomères polaires utilisés ou par l'architecture. Des modèles de copolymères EVA ont été également synthétisés par métathèse. La grande diversité d'additifs polymères à disposition combinée à des techniques d'analyse thermique et de diffusion des rayons X mises en oeuvre au plus proche de l'application (en particulier dans le gazole), ont permis de mieux appréhender leur mode d'action sur la cristallisation des n-paraffines. Les spécificités structurelles, des polymères, conditionnant leur efficacité pour le traitement de la tenue à froid des gazoles ont également pu être établiesThe additivation of diesel fuels allows operating engines at low temperatures without filter blocking and thus fulfilling legal requirements. Ethylene based copolymers such as ethylene-vinyl acetate copolymers, made by free radical polymerization at high pressure (above 2000 bars) and high temperature (above 200 °C) are frequently used as middle distillate cold flow improvers (MDFI). A new free radical copolymerization process of ethylene and vinyl acetate in organic solvent media has been developed. This process gives access to polymers close to commercial MDFI additives under tremendous less drastic conditions (under 250 bars of ethylene and 70 °C). Thanks to this process, a wide diversity (variation of the nature of the polar unit, of polymer architecture…) of ethylene based polymers was obtained. Moreover, EVA model copolymers have been synthesized by metathesis. Thanks to these numerous and diverse ethylene based polymers combined with thermal analysis and X-ray scattering studies a better understanding of the operating mode of these additives in a diesel fuel has been achieved. The structural characteristics of the polymers enabling their effectiveness as diesel fuel cold flow improvers have also been established
13
Glikman, Jean-François. "Oxydation photo-thermique des copolymeres ethylene-acetate de vinyle, ethylene-acrylate d'ethyle, ethylene-acide acrylique." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21050.
Full textAbstract:
Irradiation sous vide et dans l'air. La vitesse d'apparition des produits de photooxydation depend du type de copolymere. Cinetique et mecanisme. Mise en evidence de la labilite croissante de l'atome d'hydrogene tertiaire situe en position alpha des groupes substituants quand on passe de l'acetate a l'ethylate et a l'acide. Influence de charges et de stabilisants
14
Hlawiczka, Jakub. "Studium účinnosti polymerní přísady EVA v závislosti na ošetřovacích podmínkách malty." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240479.
Full textAbstract:
The Diploma thesis is adressing the issue of polymer-modified mortars (PMM) and theirs properties in dependence on curing conditions. The reasons of using polymer additives and some selected applications of PMM are described in theoretical part of this work. Cementitious composite (mortar) hardening is especially focused on mechanism of formation co-matrix system based on cement hydration products and polymer film in dependence on curing conditions. The knowledge of interaction of cement and ethylene-vinyl acetate (EVA) copolymer is presented in the latest paragraphs of theoretical work. Following practical part presents influence of EVA to physical and mechanic properties of PMM in dependence of dosage polymer additive and exogenous factors. The study of microstructure was investigated by scanning electron microscope and high-pressure mercury porosimetry. Tests and investigations are described and evaluated.
15
Scapini, Patrícia. "Morfologia e propriedades térmicas de compósitos de HDPE/EVA com POSS." reponame:Repositório Institucional da UCS, 2008. https://repositorio.ucs.br/handle/11338/370.
Full textAbstract:
Neste trabalho foram estudados compósitos que apresentam como matriz polimérica uma blenda composta por polietileno de alta densidade (HDPE) e copolímero etileno acetato de vinila (EVA) e como nanocarga, silsesquioxano poliédrico oligomérico (POSS). Os compósitos foram processados em câmara de mistura fechada e caracterizados quanto às propriedades térmicas e morfológicas. Para a preparação dos compósitos foram variadas as concentrações dos componentes da blenda (0, 25, 50, 75 e 100%) e da nanocarga (0, 0,5, 1, 1,5, 2, 5 e 10%). Os resultados de processamento mostraram que o aumento da concentração de POSS na matriz polimérica provocou a agregação do mesmo na matriz polimérica. As análises de calorimetria diferencial de varredura e termogravimetria indicaram que o POSS não afetou as temperaturas de fusão, cristalização e degradação da matriz polimérica. Os resultados de raios X indicaram que a presença do EVA no compósito promoveu o aparecimento de domínios cristalinos em concentrações menores de POSS. A microscopia eletrônica de varredura indicou que as amostras com 1% de POSS apresentam distribuição homogênea na matriz polimérica. Por outro lado, ocorreu a formação de agregados nas amostras com 5% de POSS. Os valores de Tg obtidos por análise térmica dinâmico-mecânica indicaram que o POSS causou um efeito plastificante na fase HDPE e uma redução da mobilidade na fase EVA. Ocorreu um aumento nos valores de módulo de armazenamento com a incorporação de POSS na matriz polimérica.Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-22T19:03:21Z No. of bitstreams: 1 Dissertacao Patricia Scapini.pdf: 2020883 bytes, checksum: 2c7249d3915135dd5f3cba151cf459db (MD5)
Made available in DSpace on 2014-05-22T19:03:21Z (GMT). No. of bitstreams: 1 Dissertacao Patricia Scapini.pdf: 2020883 bytes, checksum: 2c7249d3915135dd5f3cba151cf459db (MD5)
In this study composites with a polymeric matrix comprising a blend of high density polyethylene (HDPE) and the copolymer ethylene vinyl acetate (EVA), and with polyhedral oligomeric silsesquioxane (POSS) as the nanoclay, were processed and characterized. The composites were processed in a closed mixing chamber and characterized in terms of their thermal and morphological properties. For the preparation of the composites the concentrations of the blend components (0, 25, 50, 75 and 100%) and of the nanoclay (0, 0.5, 1, 1.5, 2, 5 and 10%) were varied. The results of the processing showed that an increase in the POSS concentration in the polymeric matrix caused the aggregation of the system. The differential scanning calorimetry and thermogravimetry analyses indicated that the POSS did not affect the melt, crystallization and degradation temperatures of the polymeric matrix. The X-ray results indicated that the presence of EVA in the composite led to the appearance of crystalline domains at lower POSS concentrations. Scanning electron microscopy indicated that the samples with 1% of POSS have a homogeneous distribution in the polymeric matrix. However, the formation of aggregates occurred in samples with 5% of POSS. The Tg values obtained from the thermo dynamic mechanical analysis indicated that the POSS had a plasticizing effect on the HDPE phase and caused a reduction in the mobility of the EVA phase. There was an increase in the storage modulus values with the incorporation of POSS into the polymeric matrix.
16
Croot, Robert Arthur. "The characterisation and adsorption of vinyl alcohol vinyl acetate copolymers." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303767.
Full text
17
Bailly, Nathalie. "N-vinylpyrrolidone-vinyl acetate block copolymers as drug delivery vehicles." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20133.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The primary aim of this study was to investigate the feasibility of the amphiphilic block copolymer poly((vinylpyrrolidone)-b-poly(vinyl acetate)) (PVP-b-PVAc) as a vehicle for hydrophobic anti-cancer drugs. PVP-b-PVAc block copolymers of constant hydrophilic PVP block length and varying hydrophobic PVAc block lengths were synthesized via xanthate-mediated controlled radical polymerization (CRP). The methodology consisted of growing the PVAc chain from a xanthate end-functional PVP. In an aqueous environment the amphiphilic block copolymers selfassembled into spherical vesicle-like structures consisting of a hydrophobic PVAc bilayer membrane, a hydrophilic PVP corona and an aqueous core. The self-assembly behaviour and the physicochemical properties of the self-assembled structures were investigated by 1H NMR spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and dynamic and static light scattering. Drug loading studies were performed using a model hydrophobic drug, clofazimine, and a common anti-cancer drug paclitaxel (PTX) to evaluate the potential of the PVP-b-PVAc block copolymers for drug delivery,. Clofazimine and PTX were physically entrapped into the hydrophobic domain of the self-assembled PVP-b-PVAc block copolymers via the dialysis method. The drug-loaded PVP-b-PVAc block copolymers were characterized regarding particle size, morphology, stability and drug loading capacity in order to assess their feasibility as a drug vehicle. The polymer vesicles had a relatively high drug loading capacity of 20 wt %. The effect of the hydrophobic PVAc block length on the drug loading capacity and encapsulation efficiency were also studied. Drug loading increased with increasing the hydrophobic PVAc block length. The effect of the drug feed ratio of clofazimine and PTX on the drug loading capacity and encapsulation efficiency were also investigated. The optimal formulation for the drug-loaded PVP-b-PVAc was determined and further investigated in vitro. The size stability of the drugloaded PVP-b-PVAc block copolymers was also assessed under physiological conditions (PBS, pH 7.4, 37 °C) and were stable in the absence and presence of serum. PVP-b-PVAc block copolymers were tested in vitro on MDA-MB-231 multi-drug-resistant human breast epithelial cancer cells and normal MCF12A breast epithelial cells to provide evidence of their antitumor efficacy. In vitro cell culture studies revealed that the PVP-b-PVAc drug carrier exhibited no cytotoxicity towards MDA-MB-231 and MCF12A cells, confirming the biocompatibility of the PVP-b-PVAc carrier. In vitro cytotoxicity assays using clofazimine-PVPb- PVAc formulations showed that when MDA-MB-231 cells were exposed to the formulations, an enhanced therapeutic effect was observed compared to the free drug. Cellular internalization of the PVP-b-PVAc drug carrier was demonstrated by fluorescent labeling of the PVP-b-PVAc carrier. Fluorescence microscopy results showed that the carrier was internalized by the MDAMB- 231 cells after 3 hours and localized in the cytoplasm and the perinuclear region. Overall, it was demonstrated that PVP-b-PVAc block copolymers appear to be promising candidates for the delivery of hydrophobic anti-cancer drugs.
AFRIKAANSE OPSOMMING: Die studie is gebaseer op die gebruik van amfifieliese blokkopolimere van poli((Nvinielpirolidoon)- b-poli(vinielasetaat)) (PVP-b-PVAc) as potensiële geneesmiddeldraers. PVP-b-PVAc blokkopolimere van konstante hydrofiliese bloklengte en verskillende hydrofobiese bloklengte is voorberei via die RAFT/MADIX-proses. Blokkopolimere met vinielasetaat is vanaf poli(N-vinielpirolidoon) met ‘n xantaatendfunksie voorberei. In ‘n wateromgewing vorm die PVP-b-PVAc blokkopolimere vesikel strukture met ‘n hydrofobiese membraan en ‘n hydrofiliese mantel. Die fisies-chemiese eienskappe van die PVP-b-PVAc blokkopolimere is gekarakteriseerd met gebruik van KMR spektroskopie, fluoresent spektroskopie, transmissie elektronmikroskopie (TEM) en dinamiese en statiese lig verstrooiing. Die potensiaal van PVP-b-PVAc as ‘n geneesmiddeldraer is ondersoek deur gebruik te maak van die hydrofobiese geneesmiddel, clofazimine, en ‘n anti-kanker geneesmiddel, paclitaxel. Clofazimine en paclitaxel is ge-inkapsuleer in die hydrofobiese gedeelte van die blokkopolimere via die dialise-metode. Clofazimine-PVP-b-PVAc en paclitaxel-PVPb- PVAc blokkopolimere is gekarakteriseerd met betrekking tot die partikel grootte, morfologie, stabiliteit en laai kapasitiet om die PVP-b-PVAc blokkopolimere as geneesmiddeldraers te evalueer. Die PVP-b-PVAc geneesmiddeldraer het ‘n relatiewe hoë laai kapsiteit van 20 gew % aangetoon. Die invloed van die bloklengte op die laai kapasitiet is ook ondersoek en beskryf. ‘n Toename in die laai kapasitiet is gesien met ‘n toename in die hydrofobiese bloklengte. Die invloed van die hoeveelheid geneesmiddel op die laai kapasitiet en die inkapsuleer doeltreffendheid is ook ondersoek. Die optimale formulasie is gevind en verder gebruik vir in vitro studies. Die stabiliteit van die geneesmiddeldraer in fisiologiese omstandighede (pH 7.4, 37 °C) is ook beskryf. Resultate toon aan dat die sisteem stabiel is onder hierdie omstandighede in die afwesigheid en aanwesigheid van serum. In vitro eksperimente is op MCF12A epiteel-borsselle en MDA-MB-231 epiteelborskankerselle getoets om die anti-tumoraktiwiteit te ondersoek. Resultate toon aan dat die PVP-b-PVAc geen sitotoxiese effek op die selle het nie, wat aandui dat die polimere bioverenigbaar is. Verder is dit bewys dat die PVP-b-PVAc geneesmiddel formualsie ’n hoër sitotoxisiteit besit as die vry-geneesmiddel. Fluoresent studies het aangetoon dat die geneesmiddeldraer na 3 uur opgeneen word deur MDA-MB231 selle en gelokaliseerd is in die sitoplasma en in die omgewing van die kern van die selle. In die algemeen is dit aangetoon dat PVP-b-PVAc blokkopolimere potensiële kandidate vir die lewering van hydrofobiese geneesmiddels is.
18
Wood, Timothy John. "An adsorption study of vinyl alcohol/vinyl acetate copolymers on polystyrene by quartz microbalance." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261278.
Full text
19
Khan, Shadeed. "Controlled Release of Fluoride from Poly(ethylene-co-vinyl acetate) Films." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1928.
Full textAbstract:
The development of aesthetically unattractive white spots is a concern for patients undergoing fixed orthodontic treatment. Due to poor oral hygiene during treatment, accumulation of plaque around orthodontic brackets causes bacterial fermentation reactions producing acids that dissolve the mineral enamel. Such dissolution results in white spot formation, an early sign of dental caries. In principal, to inhibit the appearance of these spots during treatment, fluoridated elastomeric o-rings might be employed. Once placed around brackets, these o-rings should release fluoride therapeutically for at least 30 days, after which the orthodontist may replace them. At the present time, such fluoride-releasing o-rings are not available. In this study, model materials for fluoride-releasing elastomeric o-rings were developed. These materials were fluoride-impregnated poly(ethylene-co-vinyl acetate) (PEVA) films. In vitro release studies of these films were conducted, assessing their capacity to deliver fluoride within therapeutic range (1.2 ≤ µg F/ring/day ≤ 51.4) for 30-45 days. Optimal sample and experimental parameters, including (1) fluoride loading in the film (wt% F), (2) overcoat thickness, and (3) temperature that provided therapeutic release, were determined. At 37°C, favorable release was observed for the following: (1) films with overcoat thickness of 0.14 mm and fluoride loadings of 3.9 wt% and 5.7 wt% and (2) films with overcoat thickness of 0.27 mm and fluoride loading of 5.7 wt%. These results are important in providing fundamental guidance for the development of o-rings that combat white spot formation among orthodontic patients.
20
Bellam, Balaji Anand. "Effect of e-beam sterilization on polypropylene/ethylene propylene diene monomer and ethylene vinyl acetate thermoplastic elastomer." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52484/.
Full textAbstract:
Thermoplastic elastomer is one of the priority polymeric compound identified for promotion and further development, given the growing demand for a number of commercial industries such as automobile, construction, footwear, healthcare, medical and food packaging sectors. In this study polypropylene (PP)/ethylene propylene diene monomer (EPDM) based thermoplastic elastomers are preferred for improving their properties as it can serve as a good replacement for PP or EPDM material, bridging the gap between thermoset and thermoplastic materials. This study focuses to develop PP/EPDM which can resist changes or improve properties when exposed to E-beam radiation, as E-beam also offers sustainable sterilization at low cost. The PP/EPDM blends with mixing ratios of 80/20, 50/50 and 20/80 were melt blended with the process parameters optimized using Design of experiments (DOE). The effect of E-beam on mechanical properties, thermal stability, crystallization and dynamic mechanical properties over the dose of 0 to 100 kGy were studied. The blends with high EPDM content (20PP/80EPDM) showed improvement in tensile strength up to 36% (at 40kGy and 60kGy) and resistant to impact strength up to 100 kGy, at the expense of elongation at break. On the other hand, the blends with high PP content (80 PP/20 EPDM and 50 PP/50 EPDM) showed detrimental effects on mechanical properties at all radiation dose studied and found to be not compatible for E-beam sterilization. Further, ethylene vinyl acetate (EVA) was incorporated to PP/EPDM blends at 10EVA/40EPDM/50PP, 20EVA/30 EPDM/50PP, 30EVA/20 EPDM/50PP and 40EVA/10 EPDM/50PP ratios. The gel content analysis showed that the efficiency of crosslinking decreased with increase in EVA loading. However, the presence of EVA in ternary blend especially facilitated the induction of sufficient crosslinks leading to improvement in tensile strength (up to 29% at 60 kGy), impact strength (up to 15% at 80 kGy) and retention of stiffness and thermal properties under radiation at the expense of elongation at break. In order to develop antibacterial ternary blends, silver nanoparticles (AgNP) were added by varying the loading from 0.3wt% to 1wt%. The Ag-ternary blends showed enhancement in impact properties (up to 9%) at the expense of decrement in tensile properties due to the agglomeration of AgNP. When, exposed to E-beam radiation, the mechanical and thermal properties exhibited similar trend of increment and decrement across radiation dose similar to the blends without AgNP. While, 1% Ag blend composites showed bacteriostatic effect on Staphylococcus aureuson, no significant reduction of Pseudomonas aeruginosa bacteria was observed. All the blends, before and after sterilization showed no significant toxicity on HaCaT cells investigated using in vitro analysis. Thus, the blends showed an instinct that their application could be extended to manufacturing of healthcare products and food packaging sector, as they are biocompatible and can withstand E-beam sterilization as demanded by the respective application. Among all the blends ternary blends studied (that exhibited biocompatibility even after radiation), 20EVA/30EPDM/50PP without AgNP showed the highest tensile strength of 18.41 MPa and impact strength of 43.64 J/m. Only a slight increase in tensile and impact properties was witnessed upon addition of 20% EVA to PP/EPDM blend in comparison to the binary blend (50PP/50EPDM blend). However, unlike the binary blend (whose properties decreased upon radiation), the ternary blend (20EVA/30EPDM/50PP) showed improvement in tensile strength up to 29% at 60kGy and up to 15% increase in impact strength at 80kGy.
21
Muriel, Galet Virginia. "Novel antimicrobial films based on ethylene-vinyl alcohol copolymers for food packaging application." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/48522.
Full textAbstract:
This PhD dissertation thesis has been focus on the development and characterization of
antimicrobial packaging films based on the incorporation in the polymer matrix or on
the attachment to the film surface of naturally occurring antimicrobial compounds with
the purpose of inhibiting the proliferation of microorganisms and extend the microbiological
shelf life of packaged food products.
The studied active films are based on the use of ethylene vinyl copolymers (EVOH) containing
29% (EVOH29) or 44% (EVOH44) molar percentage of ethylene as polymeric vehicle
for the incorporation of several antimicrobial compounds -oregano essential oil (OEO),
citral, ethyl lauroyl arginate (LAE), epsilon-polylysine (EPL), green tea extract (GTE) and
lysozyme. These antimicrobial agents have been incorporated in the film-forming solution
or immobilized to the film surface by covalent bonding.
Prior to the preparation of the active films, the antimicrobial activity of the selected compounds
against selected microorganism was demonstrated, confirming that they could be
good candidates to be used as preservatives for active food packaging applications, and
an alternative to synthetic additives. The effect of the incorporation of the antimicrobial
agents on relevant functional properties of the developed EVOH films was studied.
In general, the polymer properties as materials for food packaging were not relevantly
affected.
In order to evaluate the potential of EVOH matrices as sustain release systems of active
compounds, the release kinetics of the active compounds from the film to different media
was evaluated; for that the agent release rate and extend into food simulants was
monitored, and it was concluded that the agent concentration, release temperature, type
of EVOH, interaction of EVOH with the food simulant, and the solubility of the active
compound in the release media were the main controlling factors.
EVOH matrices have also shown good properties to be used for the attachment of active
molecules. In this regard, lysozyme was successfully immobilized on the film surface of
EVOH.
Several experiments were conducted to determine the antimicrobial properties of the
resulting films in vitro against different microorganisms responsible for foodborne illness
and in vivo with real foods –minimally-process salad, infant milk, surimi sticks and chicken
stock- to enhance their preservation. All the materials presented a strong in vitro antimicrobial
activity. Although the results obtained through in vivo tests showed activity
reductions caused by food matrix effects, all materials presented significant microbial
inhibition and, therefore, great potential to be used in the design of active food packaging.
They can be applied as an inner coating of the packaging structure, releasing the active
agent or acting by direct contact, producing a great protection against contamination
with a prolongation of the microbiological food shelf life.Muriel Galet, V. (2015). Novel antimicrobial films based on ethylene-vinyl alcohol copolymers for food packaging application [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48522
TESIS
Premiado
22
Badiee, Amir. "An examination of the response of ethylene-vinyl acetate film to changes in environmental conditions." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33757/.
Full textAbstract:
Photovoltaics are used for the direct conversion of sunlight into electricity. In order to provide useful power, the individual solar cells must be connected together. This electrically connected and environmentally protected unit is termed a photovoltaic (PV) module. The structure of a PV module consists of a number of layers of various materials with different properties. The encapsulation material is one of the critical components of a PV module. It mechanically protects the devices and electrically insulates them, ideally for at least the 20-25 year lifetime of the modules. The lifetime of a PV module is generally limited by the degradation of the constituent parts. The materials degrade and cause a decrease in the efficiency leading to eventual failure, with the encapsulant being particularly susceptible to degradation. The most common encapsulant material is Ethylene Vinyl Acetate (EVA) the degradation of which leads to a significant drop in a PV module’s efficiency, durability and lifetime. EVA undergoes chemical degradation when it is exposed to environmental factors such as elevated temperature, humidity and Ultra Violet (UV) radiation. Although numerous works have been done in this field there is still a gap in knowledge to fully understand the degradation of EVA and develop a predictive tool. This work investigates the chemical degradation of an EVA encapsulant to understand the degradation mechanisms, develop a predictive model and correlate the degradation with changes in the structure and mechanical properties. To determine the effect of environmental stresses on EVA environmental conditions were simulated in the laboratory in order to accelerate the test program. The ageing was classified into three main groups, namely thermal ageing, UV ageing and damp-heat ageing. In order to investigate the effect of elevated temperature on the mechanical and thermal properties and also to study the thermal degradation, EVA sheets were aged in a dark laboratory oven at 85°C for up to 80 days. To investigate the impact of UV exposure on the properties and photodegradation of EVA the samples were exposed to UV radiation of 0.68 W/m2 at 340 nm and 50°C. To study moisture diffusion and the impact of absorbed moisture on the mechanical properties and morphology, EVA sheets were aged in an environmental chamber at 85°C-85% RH and using a potassium chloride (KCl) salt solution in a sealed chamber to obtain 85% RH at room temperature (22±3°C). Thermal analysis techniques including Differential Scanning Calorimetry (DSC), Thermo-gravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA) along with Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Gravimetrics were used to investigate the structure, degradation kinetics and viscoelastic mechanical properties of the EVA as a function of ageing. The EVA was shown to have viscoelastic properties that were highly sensitive to the ambient temperature. Thermal ageing was shown to reduce the storage modulus due to the changes in the structure of the EVA and reduction in crystallinity. Over a longer time, chemical changes due to thermal activation also occurred, hence, these were insignificant compared with transient thermal effects. The activation energy of deacetylation was also shown not be affected by the ageing process. Investigation of photodegradation showed notable chemical changes as a result of UV exposure, with FTIR absorbance peaks related to carboxylic acid, lactone and vinyl exhibiting a sharp increase after UV irradiation. Differences in the ATR-FTIR spectra of the UV irradiated and non-irradiated samples showed that the intensity is depth dependant. DMA results showed UV ageing had a significant influence on the mechanical properties of the EVA and reduces the storage modulus. The predictive photodegradation model showed a good agreement on the UV irradiated surface with the experimental data where it did not agree well with the results on the non-irradiated side which could be due to the presence of UV absorber. The response of the EVA to damp heat was investigated at two conditions with same the RH level (85% RH) and different temperatures (room temperature and 85°C). The moisture diffusion coefficient was measured via gravimetry and Water Vapour Transmission Rate (WVTR) technique which were well-agreed. Results from DSC indicated that the crystallinity increased due to incorporation of moisture into the structure of the copolymer but decreased as ageing continued, showing the significant influence of elevated temperature and thermal degradation on the structure of EVA. A comparative study of the impact of the ageing on the structure and mechanical properties indicated that UV has a stronger degrading influence comparing to other degradation factors. DSC results also suggested that property changes could be connected to structural modifications. The impact of different degradation factors can be summarised as UV > T > DH.
23
English, Hugh Edmund. "Molecular simulations of ethylene vinyl acetate for the improvement of the cold flow properties of diesel." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/molecular-simulations-of-ethylene-vinyl-acetatefor-the-improvement-of-the-cold-flow-propertiesof-diesel(735bf45e-acf0-4115-86a0-ea0c811c910a).html.
Full textAbstract:
Ethylene-vinyl acetate co-polymers are widely used as cold-flow improving additives in diesel fuels. Although their functionality is undisputed, the mechanisms of action at a molecular level are not fully understood. Theories that EVA acts as both a nucleating agent for small wax crystals and as a crystal growth inhibitor are generally acknowledged, however the understanding of the effect of structure on additive performance is limited. Studies have been carried out using molecular simulation techniques with the aims of improving the understanding of the interactions between EVA and diesel fuels, and assessing the potential of these methods for the analysis of different additive structures and fuel compositions. Firstly, the ability of Monte Carlo simulations to predict the chemical potentials of n-alkanes in organic solvents was studied. This information would be of use in determining the characteristics of different fuel compositions. It was found that the particle insertion method used becomes more efficient as the aspect ratio of the solvent increases relative to that of the solute. Despite the identification of expected linear trends in the chemical potential of n-alkanes, it was not possible to produce high quality quantitative data using this method. The effect of vinyl acetate spacing and solvent environment on the configuration of lone EVA molecules in the liquid phase was studied. Molecular dynamics showed that closely spaced vinyl acetate groups increase the tendency of the molecule to fold at that point, whilst molecules with 2 or 3 ethylene groups in between show resistance to folding. It was shown that n-hexane as a solvent produced more folded configurations than benzene and n-hexadecane respectively. Monte Carlo simulations were also performed but were largely unsuccessful. Finally, molecular dynamics simulations were performed to study the effect of different EVA structures on the spontaneous crystallisation of n-hexadecane, and the interaction of the EVA with the resulting structures at a molecular level. It was shown that different EVAs had varying effects on the crystallisation, with trends attributed to the spacing of the vinyl acetate groups and the length and position of extended aliphatic sections of the EVA molecules. One molecule, with evenly spaced side-groups and no extended aliphatic sections was shown to fully prevent the formation of any crystalline structure within the time of the simulation where all other EVA molecules allowed some degree of wax formation to occur.
24
Garlet, Givanildo. "Aproveitamento de resíduos de E.V.A. (Ethylene Vinyl Acetate) como agregado para concreto leve na construção civil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1998. http://hdl.handle.net/10183/118243.
Full textAbstract:
O desenvolvimento de novos materiais para a construção civil a partir do aproveitamento de resíduos industriais, buscando a redução do custo das habitações e a preservação do meio ambiente, apresenta vantagens que vem despertando o interesse de pesquisadores e empresários em todo o mundo. Neste trabalho é descrito o estudo para o aproveitamento, na construção civil, do resíduo de E.V.A. (Ethylene Vinyl Acetate), polímero muito utilizado na indústria calçadista para a confecção de solados e palmilhas internas de calçados. Em virtude do grande volume gerado mensalmente este material vem se acumulando ao longo dos anos em áreas a céu aberto, causando diversos problemas ao meio ambiente. O emprego dos resíduos de EVA na construção, além de contribuir para a solução do problema ambiental, pode representar uma nova fonte de receita para empresas que exploram o uso deste material. Aproveitando a baixa massa unitária deste resíduo (± 180 kg/m3) o estudo foi direcionado para o desenvolvimento de um agregado leve, a ser usado na produção de concreto e de componentes de vedação para a construção civil. O material proveniente das fábricas de calçados foi triturado em um moinho, sendo ass1m obtido um agregado de EVA com determinada granulometria. Posteriormente foi conduzido um programa experimental, onde foram avaliadas as condições de trabalhabilidade e consistência necessárias à mistura fresca, bem como as propriedades físicas e mecânicas do concreto obtido, pela mistura de cimento, areia e agregado de EVA. Os resultados mostram um novo tipo de concreto leve, cuja principal propriedade é a grande ductilidade, devido às propriedades elásticas do agregado de EVA. Como aplicações em potencial são apontadas o uso como contrapiso de lajes entrepisos para atenuação do ruído de impacto, isolamento térmico, absorção acústica, além da possibilidade de produção de alguns artefatos de cimento, desde que a resistência à compressão seja adequada, na dosagem do concreto.The development of new construction materiais, using industrial wastes, can to reduce the cost of construction and preserve the environment. These advantages have been waking the interest of researchers around world. This work describes the studies to make use of E.V.A. (Ethylene Vinyl Acetate) wastes, which is a polymer very utilized to make soles in the shoes industry. The big amount of EVA wastes producted per month has been deposited in many earth sufaces, causing many environmental problems. Therefore utilizes these wastes can represent a new source of take for business enterprises. Furthermore, can contribute to solve the environmental problems. Due to the low weight of this material the studies were conducted to find out a new Lightweight aggregate to use in the civil construction. The first step was to grind the wastes from the factories to reduce them to an aggregate. Then was developed an experimental program where the physical and mechanical properties of the concrete obtained mixing cernent, sand and EVA aggregate were analyzed. The results shown a new Lightweight aggregate concrete that can be utilized to make non structural components for construction as thermal insulation of roofs, to reduce de impact noise between slabs of the multistory building and to acoustical absorption. The studies also conclude that the strength can be control through the concrete density in the project mix.
25
Bambalaza, Sonwabo Elvis. "An investigation into the use of a ceramifiable Ethylene Vinyl Acetate (EVA) co-polymer formulation to aid flame retardency in electrical cables." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1020159.
Full textAbstract:
The concept of a unique ceramifiable Ethylene vinyl acetate (EVA) based polymer composite was based on the incorporation of inorganic compounds such as aluminium hydroxide, calcium carbonate, muscovite mica, and calcined kaolinite within a 95 percent EVA/ 5 percent Polydimethylsiloxane (PDMS) polymer matrix such tha t upon heating to elevated temperatures of about 1000 oC, a solid end-product with ceramic-like properties would be formed. The ceramifiable EVA based polymer composite was developed to be used as electric cable insulation or sheath as the formation of a ceramic based material at elevated temperatures would provide flame retardant properties during fire situations. The flame retardant properties at elevated temperatures would ensure that the insulation remains at such temperatures due to some of the properties of the resultant ceramic such as reasonably high flexural strength, high thermal stability, non-reactivity and high melting point. During a fire this would ensure that flames would not be propagated along the length of the cable and also protect the underlying conducting wires from being exposed to the high temperatures of the fire. Its application as a cable insulation also required that the material functions as a cable insulator under ambient temperature conditions where the ceramifiable polymer composite should retain certain polymer properties such as the post-cure tensile strength (MPa), degree of polymer elongation (percent), thermal expansion, thermal slacking, limited oxygen index and electrical insulation. This study made use of a composite experimental design approach that would allow for the optimization of the amounts of the additives in the ceramifiable polymer composite giving both the desired mechanical properties of the material under normal operating temperatures as a polymer and also as a ceramic once exposed to elevated temperatures. The optimization of additives used in the ceramifiable polymer composite was done by using a D-optimal mixture design of experiments (DoE) which was analyzed by multiple linear regression.
26
Savant, Deepa. "Multidimensional NMR studies of terpolymers poly(ethylene-co-vinyl acetate-co-carbon monoxide) and poly(ethylene-co-1-hexene-co-carbon monoxide)." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1153685162.
Full text
27
Guclu, Mehmet. "Light Stability And The Effect Of Temperature On Mechanical Properties Of Polypropylene / Poly(ethylene-vinyl-acetate) Blends." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608535/index.pdf.
Full textAbstract:
The variation in properties of Polypropylene (PP) / Ethylene Vinyl Acetate (EVA) blends upon EVA content, temperature, and light stability were followed by using tensile testing, impact testing, and differential scanning calorimetry (DSC).
Young&rsquos modulus of the blends decreased with increasing drawing temperature and EVA content. The stress at break values of the blends slightly increased with EVA whereas decreased with drawing temperature. The percent strain at break values of the blends were found to increase abruptly by increasing EVA content and drawing temperature. These changes in the mechanical properties are the indication of compatibility. The impact tests were performed only at 0°
C, 25°
C and the impact strength increased with the temperature and EVA content, but none of the samples were broken at higher testing temperatures. The effect of stabilizer was very obvious because stabilizer-free samples failed after 400 hours whereas, the samples with stabilizer resisted up to 750 hours. Elongation values of the samples decreased because of increasing brittleness by UV irradiation. We also observed chain stiffening effect by crosslinking in all samples upon UV irradiation. Thermal analysis of the blends of the drawn samples showed an increasing trend of crsytallinity with increasing drawing temperature. Increasing drawing temperature made polymer chains more flexible because of the increasing chain mobility. These flexible chains were then oriented in one direction during tensile testing and therefore uniaxial crystallization occurred. The morphology of impact and tensile tests samples were also analyzed by scanning electron microscope (SEM). The fibrillation of pure PP is higher than the fibrillation of the blends.
28
Lehman, Stephen E. "Ruthenium catalysis in metathesis polymerization synthesis of linear copolymers of ethylene and polar vinyl monomers via metathesis /." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001021.
Full text
29
Cheetham, Paul Frederick. "An ESR study of the slurry preparation of acrylonitrile/ vinyl acetate copolymers, and corresponding NMR characterisation of their microstructures." Thesis, Lancaster University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386966.
Full text
30
Ramarad, Suganti. "Improving the properties of reclaimed waste tire rubber by blending with poly(ethylene-co-vinyl acetate) and electron beam irradiation." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/31278/.
Full textAbstract:
Non-degradable waste tire generation around the world is growing at an alarming rate. Diversifying the recycling route of these waste tires is essential to solve the problem. One way is to incorporate them into polymers and convert them into new products. However, incorporation of ground tire rubber into thermoplastics has been hampered due to lack of toughness and adhesion between phases. To address the issue, this study utilized reclaimed waste tire rubber (RTR) instead; and evaluated the properties of RTR and poly(ethylene-co-vinyl acetate) (EVA) blends. The properties of the RTR/EVA blends were further enhanced by compatibilization and electron beam irradiation. Processing, mechanical, thermal and dynamic mechanical properties of RTR were tremendously improved by blending with EVA. However, the interfacial adhesion was found to lack in the blends. Compatibilization by reactive, physical and combination strategies were explored utilizing (3-Aminopropyl)triethoxy silane (APS), liquid styrene butadiene rubber (LR) and maleated EVA (MAEVA), respectively. APS and MAEVA were found to be the most and least favourable compatibilizer, respectively. Apart from functioning as reactive compatibilizer, APS also reclaimed the RTR phase further. These lead to improved dispersion of smaller RTR phase in EVA matrix and enhanced the interfacial adhesion. Electron beam irradiation revealed the presence of radical stabilizing and scavenging additives within RTR which retards the crosslinking process in RTR and RTR/EVA blends. Though chain scissions were predominant; study showed the replacement of S-S and S-C bonds with stronger and stiffer C-C bonds ensures the retention of RTR and RTR/EVA blends properties upon irradiation. Compatibilization of RTR/EVA blend by APS (50RTR/5APS) also improved the crosslinking efficiency. However, the blend still suffered from oxidative degradation from irradiation in air. Radiation sensitizers, trimethylol propane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA) and N,N-1,3 Phenylene Bismaleimide (HVA2), were used to accelerate the irradiation induced crosslinking in RTR and 50RTR/5APS blends. Presence of radiation sensitizers leads to simultaneous improvement in toughness and tensile strength of RTR and 50RTR/5APS blends. Elastic capacity of RTR phase was restored and interfacial adhesion enhanced in the presence of radiation sensitizers.
31
Morin, Aurélie. "Controlled radical polymerization of vinyl esters and vinyl amides : experimental and theoretical studies." Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0117/document.
Full textAbstract:
Ces travaux de thèse portent sur la polymérisation radicalaire contrôlée (PRC) des esters et amides de vinyle. L’une des possibilités de contrôle est le piégeage dynamique réversible des chaînes radicalaires croissantes (P•) par un agent de contrôle (T) formant une espèce dormante (P─T’). La concentration en radicaux dans le milieu peut alors diminuer dramatiquement de sorte que les réactions indésirables de terminaisons soient négligeables et que le contrôle de la masse molaire des polymères soit atteint avec un faible indice de dispersité. L’utilisation de complexes métalliques, pouvant s’oxider et former une liaison métal-carbone, comme agent de piégeage des radicaux est une manière de réaliser ce contrôle. La PRC est alors appelée Polymérisation Radicalaire Contrôlée par voie Organométallique (OMRP). A ce jour, plusieurs métaux de transitions ont été utilisés avec plus ou moins de succès en OMRP. Lors de cette étude, nous avons synthétisé des complexes de cuivre(I) et testé leurs performances pour l’OMRP de l’acétate de vinyle et de l’éthylène. Nous avons également utilisé des outils de chimie théorique pour mieux comprendre pourquoi le cobalt(II) acétylacétonate est, jusqu’à aujourd’hui, le meilleur agent de contrôle pour la polymérisation de l’acétate de vinyle et des amides de vinyle. Grâce à la théorie de la fonctionnelle de densité (DFT), nous avons mis en lumière le rôle crucial de la coordination sur le cobalt des groupements carbonyles des monomères étudiésThis thesis focus on Controlled Radical Polymerization (CRP) of vinyl esters and vinyl amides. One of the possibilities to achieve this control is a dynamic reversible trapping of the growing radical chains (P•) by a controlling agent (T) to form a dormant species (P─T’). The radical concentration in the medium can be dramatically reduced so that the unwanted terminations are disfavored and polymers with controlled molecular weights and low dispersity can be obtained. A way to achieve this control is the use of metallic complexes, which can oxidize and form a metal-carbon bond, as trapping agent in the so-called Organometallic Mediated Radical Polymerization (OMRP). So far, different transition metals have been used with gretaer or smaller success. In this study, the synthesis of copper(I) complexes and their investigation for the vinyl acetate and ethylene polymerization under OMRP conditions were performed. We also used computational chemistry as a tool to better understand why the cobalt(II) acetylacetonate (Co(acac)2) has, so far, given the best results for either vinyl acetate or vinyl amides polymerization. Thanks to Density Functional Theory (DFT), the crucial role of the monomer carbonyl group coordination to cobalt was pointed out
32
Jin, Yu [Verfasser], Dietmar [Akademischer Betreuer] Stephan, Oliver [Gutachter] Weichold, Dietmar [Gutachter] Stephan, and Wolf-Dieter [Gutachter] Hergeth. "Interaction between vinyl acetate-ethylene latex stabilized with polyvinyl alcohol and Portland cement / Yu Jin ; Gutachter: Oliver Weichold, Dietmar Stephan, Wolf-Dieter Hergeth ; Betreuer: Dietmar Stephan." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156179033/34.
Full text
33
Wheeler, Nicholas Robert. "Lifetime and Degradation Science of Polymeric Encapsulant in Photovoltaic Systems: Investigating the Role of Ethylene Vinyl Acetate in Photovoltaic Module Performance Loss with Semi-gSEM Analytics." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1473440287427776.
Full text
34
Langer, Filip. "Vliv okolních podmínek na recyklaci solárních modulů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442429.
Full textAbstract:
This thesis is focused on experiments, goal of which is to separate protective glass apart from thin layer solar panel. This could lead to less expensive and more efficient recycling. We try to achieve the separation of the glass by thawing ethylene vinyl acetate layer, which serves as insulant and bonding material. Experiments are concluded in high temperature dryer and high temperature vacuum oven on samples of thin layer solar panel, which is for the purposes of experiments cut into same pieces by water jet cutting machine. The initiatory experiments in dryer and oven are to determine value of ethylene vinyl acetate thaw point in tested samples of panel. The thaw point is determined to be 340 °C. When exposed to this temperature, the ethylene vinyl acetate thaws enough for glass to be able to be extracted with minimal physical strength. The process is accompanied by fire destruction of tedlar layer and creation of exhaust gases. Following experiments in vacuum and nitrogen environment are to test their influence on thawing process. Exposing sample to temperature of 340 °C in vacuum led to no new results. Exposing sample to temperature of 340 °C in nitrogen environment prevented fire and achieved same level of thawing of ethylene vinyl acetate while creating less exhaust gases. Even though the fire was prevented, tedlar layer was still destroyed by the high temperature. Furthermore, particles of evaporated ethylene vinyl acetate condensed on surface of module in form of dust. Following experiments studied absorption of panel and influence of accessible solvents on thawing process. It was determined that panel is able to absorb approximately 2 % of acetone, 0,4 % of isopropyl alcohol and 0,11 % of distilled water in its own weight. Experiments with modules soaked in these solvents proved no new results in thawing process. By observing samples of ethylene vinyl acetate taken from module, thawed out of module after experiment in vacuum oven and dust condensed on surface of module after experiment in nitrogen environment, it was proven that the condensed dust is indeed ethylene vinyl acetate.
35
Cankaya, Burhan Fuat. "Foamed Eva-bitumen Blends And Composites." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610215/index.pdf.
Full textAbstract:
The thermal conductivities of foamed polymer based materials are much lower thermal conductivity values than unfoamed polymeric materials. Especially, thermal conductivity values of foamed polymers with closed-cell structure decreases to 0.03
W/m.K. The reinforcement of foamed polymeric materials by mixing with bitumen lowers the raw material cost.
The main objective of this study is to make a new thermal insulation material with low thermal conductance. In this study, the effects of concentration of calcium carbonate as inorganic filler and the effects of cross-linking on the properties foamed and unfoamed ethylene-vinyl acetate (EVA) copolymer based bituminous blends and composites were investigated. Applications such as thermal, mechanical characteristics of foamed and unfoamed EVA based bituminous composites were investigated.
Foamed EVA based bituminous composites were prepared by using Brabender Plastic Coder, PLV 151. Mixing was made at 120 ºC at 60 rpm for 15 minutes. The prepared blends were molded by a technique called Hand Lay-up Self-expanding Batch Molding (HLUSEBM) which was firstly applied by our group. The molding temperature was 170 º
C at which chemical blowing agent and cross-linking agent decomposes. According to test results, at moderate chemical blowing agent and EVA content, the best closed-cell structure with high porosity and low thermal conductivity values were obtained. The compressive properties of foamed polymer based bituminous composites (FPBBCs) increase with increasing CBA and EVA content. With increasing calcium carbonate and EVA concentration, the porosity of FPBBCs increases but thermal conductivity of them decreases. On the other hand, with increasing filler content but with decreasing EVA concentration elastic modulus of FPBBCs increases but elastic recovery decreases.
36
Debnáriková, Michaela. "Krystalizace dvousložkových směsí polylaktidu a jejich morfologie." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444214.
Full textAbstract:
Master thesis deals with the influence of polyvinylacetate, polycaprolactone, poly(butylene-adipate-co-terephtalate) and talc, ethylenevinylacetate, polyethylene glycol and monosodium citrate on the flow properties, mechanical properties and crystallization ability of PLA. The flow properties were studied using the melt flow index and mechanical properties were studied using a tensile test. The crystallinity was studied by differential scanning calorimetry and on a polarization optical microscope equipped with hot stage. Isothermal crystallization was performed at 95 and 105 °C for 3 h and non-isothermal crystallization was performed with a calorimeter at two cooling rates (1 and 10 °C/min). Upon the isothermal crystallization at 95 °C, the formation of denser crystalline structure was observed and the content of crystalline phase increased in most of the samples. The formation of spherulitic structure was observed at 105 °C in samples with 30 % PVAc, 30 % EVA and PEG. Reducing the cooling rate to 1 °C/min at non-isothermal crystallization had nearly no effect on the crystallization process of the most samples; the content of crystalline phase increased in the samples containing PBAT and PEG, which revealed double melting peak during subsequent heating. The crystalline fraction was the most significantly affected by the addition of PEG. All added polymers except PVAc affected the mechanical properties; PBAT, PCL, EVA and PEG increased the strain and decreased the strength and modulus of elasticity. The samples containing monosodium citrate showed unsatisfactory mechanical properties and could not be measured. The samples containing higher concentration of EVA copolymer showed the phase separation.
37
Lim, Henry C. A. "The influence of reactive modification on the compatibility of polyolefins with non-olefinic thermoplastics." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8372.
Full textAbstract:
Polyethylene (PE) resins being non-polar in nature and having a high degree of crystallinity have limited miscibility and compatibility when blended with polar polymers. The miscibility and compatibility of these blends are generally worsened when they are prepared by direct injection moulding without a precompounding process. Such situations are commonly encountered in particular by polymer converters when blending colour and/or additive concentrates, commonly known as masterbatches. Typically, masterbatches are mixtures containing high loading of pigments and/or additives predispersed in a suitable solid vehicle (commonly known as carrier) such as a polyethylene resin. These masterbatches are usually used for the colouration of a wide range of polymers and the carrier used must therefore be compatible with these matrix (host) polymers. The preliminary stage of this study involved the investigation of the properties of blends based on high density polyethylene (HDPE) and a range of engineering thermoplastics (ABS, PC, PBT, PA6), prepared by injection moulding. Five different types of compatibilisers namely, ethylene-vinyl acetate (EVA) copolymer, ethylene-methyl acrylate (EMA) copolymer, ethylene-glycidyl methacrylate (E-GMA) copolymer, ethylene-methyl acrylateglycidyl methacrylate (E-MA-GMA) terpolymer and maleic anhydride grafted HDPE (HDPE-g-MAH) copolymer were evaluated with respect to their efficiencies in compatibilising HDPE with the four engineering polymers. The pre-compounded HDPE/compatibiliser binary blends at 2 different blend ratios (1:1 and 3:1) were added at 15 wt% concentration to each engineering thermoplastics and test samples were produced directly by injection moulding. Results of mechanical testing and characterisation of the blends showed that glycidyl methacrylate compatibilisers, E-MA-GMA, in particular have the most universal compatibilising effectiveness for a range of engineering thermoplastics including ABS, PC, PBT, and PA6. Blends compatibilised with E-MA-GMA compatibiliser had the best notched impact performance irrespective of matrix polymer type. The presence of an acrylic ester (methyl acrylate) comonomer in E-MA-GMA resulted in increased polarity of the ii compatibiliser leading to improved miscibility with the polar matrix polymers demonstrated by fine blend morphologies, melting point depression and reduction in crystallinity of the HDPE dispersed phase. The second stage of this study involved the reactive modification of HDPE using a low molecular weight di-functional solid diglycidyl ether of bisphenol A (DGEBA) type epoxy resin compatibilised with HDPE-g-MAH in an attempt to improve its compatibility with ABS, PBT and PA6. The maleic anhydride moieties in HDPE-g-MAH served as reactive sites for anchoring the epoxy moieties while the HDPE backbone was miscible with the HDPE resin. An excessive amount of reactive groups resulted in the formation of crosslinked gels while the addition of EVA co-compatibiliser helped in the reduction of gel content and further improved the dispersion of the epoxy. The effectiveness of epoxy grafted HDPE (with and without EVA co-compatibiliser) in compatibilising ABS/HDPE, PBT/HDPE, and PA6/HDPE was investigated by injection moulding of 5 wt% functionalised HDPE with these matrix polymers into test bars for mechanical testing, and characterisation by differential scanning calorimtery (DSC) and optical microscopy. The reactively functionalised HDPE blends, improved the mechanical properties of ABS and PA6 blends especially with EVA as co-compatibiliser. However, the mechanical properties of PBT blends were unmodified by the functionalised HDPE which was believed to be due to end-capping of the PBT chain-ends by ungrafted epoxy resins.
38
Ildefonso, Jesner Sereni. "Análise da viabilidade técnica da utilização do copolímero etileno acetato de vinila (EVA) descartado pela indústria calçadista em misturas asfálticas (processo seco)." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18143/tde-13032007-112426/.
Full textAbstract:
A presente dissertação teve por objetivo analisar o comportamento de misturas asfálticas modificadas, pelo processo seco, com o copolímero etileno acetato de vinila (EVA), resíduo sólido descartado pela indústria calçadista. Em razão das características do EVA, acredita-se que ele possa melhorar as características mecânicas de misturas asfálticas e a resistência ao desgaste. A maioria dos pesquisadores tem direcionado seus esforços em estudos de misturas asfálticas modificadas pelo processo úmido, porém, devido à natureza do resíduo analisado neste trabalho, optou-se pelo processo seco, que demanda menos energia por não necessitar de moagem do material. A pesquisa compreendeu o estudo de amostras de misturas asfálticas não envelhecidas e com envelhecimento de duas e quatro horas em estufa, com moldagem de corpos-de-prova para realização dos ensaios de resistência à tração por compressão diametral estática, módulo de resiliência por compressão diametral, fluência por compressão uniaxial estática e dinâmica, vida de fadiga e desgaste por abrasão (ensaio Cantabro). Os resultados mostram que a utilização deste resíduo aumentou a resistência das misturas à fadiga e ao desgaste de forma significativa, porém as misturas tornaram-se mais susceptíveis à deformação permanente. O tempo de envelhecimento de curto prazo se mostrou importante, pois aumentou a resistência das misturas à fadiga e à deformação permanente.The main purpose of the present master thesis was to analyze the behavior of modified hot-mix asphalt, through the dry process, with the copolymer ethylene vinyl acetate (EVA) discarded by the footwear industry. Since the EVA characteristics, it is believed that it can improve hot-mix asphalt mechanic characteristics and the wear and tear resistance. Most of the researchers have been addressing efforts in studies on modified hot-mix asphalt by the wet process, however, due to the nature of the solid residue analyzed in this work, the dry process will demand less energy for not needing of grinding. The research evolved the study of samples of asphalt mixtures not aged and with aging of two and four hours in oven, submitted to indirect tension test, resilient modulus, static and dynamic creep, fatigue life and loss due to abrasion (Cantabro test). The results show that the use of this residue increased the resistance of the mixtures to the fatigue and loss of mass due to abrasion, however the mixtures became more susceptible to the permanent deformation. The short-time aging was shown important, because it increased the resistance of the mixtures to the fatigue and the permanent deformation.
39
Dommanget, Cédric. "Polymérisation radicalaire contrôlée : le défi de l'éthylène." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10216/document.
Full textAbstract:
Les travaux présentés dans cette thèse portent sur le contrôle de la polymérisation radicalaire de l'éthylène à basse pression (200 bar) et basse température (70 °C) et sur la synthèse de copolymères à blocs contenant au moins un segment de polyéthylène. Quatre techniques de polymérisation, couramment utilisées en ingénierie macromoléculaire, ont été étudiées : NMP, CMRP, RAFT/MADIX et ESCP. Nos études sur le nitroxyde SG1 (NMP) et le bis(acétylacétonate) de cobalt (CMRP) ont montré que ces composés sont inefficaces pour contrôler la polymérisation de l'éthylène. Un comportement inattendu du bis(acétylacétonate) de cobalt a cependant été mis en évidence. Il semblerait que ces complexes de cobalt favorisent les réactions de couplage entre les radicaux propagateurs. En revanche, la première polymérisation radicalaire contrôlée de l'éthylène a été atteinte grâce à l'utilisation de xanthates (RAFT/MADIX). Les polyéthylènes synthétisés possèdent des masses molaires qui augmentent linéairement avec la conversion et des dispersités faibles. Le caractère pseudo-vivant de la réaction a été démontré par la synthèse de copolymères à blocs poly(acétate de vinyle)-b-polyéthylène. L'utilisation de nitrones (ESCP) a également permis l'introduction d'une fonction réactive au centre des chaînes de polyéthylène et la synthèse de copolymères triblocs de type ABA, où les blocs latéraux A sont en polystyrène ou polyacrylate et le bloc central B est en PolyéthylèneThe work presented in this thesis displays the controlled radical polymerization of ethylene at low temperature (70 °C) and low pressure (200 bar) and the synthesis of block copolymers featuring polyethylene segments. Four polymerization techniques, commonly used in macromolecular engineering, were studied: NMP, CMRP, RAFT/MADIX and ESCP. Our investigation of the use of SG1 nitroxide (NMP) and cobalt (II) acetylacetonate (CMRP) as controlling agents demonstrated their inability to control the polymerization of ethylene. Nonetheless, an unexpected reaction with cobalt (II) acetylacetonate was observed. The coupling reaction between propagating radicals appeared to be favored by the presence of this compound. On the other hand, the first controlled polymerization of ethylene was successfully achieved by using xanthate (RAFT/MADIX). A linear increase of molecular weight with conversion and low polydispersities were observed for the produced polyethylenes. The reaction was demonstrated to be a pseudo-living polymerization by the synthesis of block copolymers poly(vinyl acetate)-b-polyethylene. In addition, midchain-functionalized polyethylenes and ABA type block copolymers, with polystyrene or polyacrylate as the A block and polyethylene as the B block, were also prepared using nitrone based polymerization technique (ESCP)
40
Brien, Joshua V. "DEVELOPMENT OF CEMENTITIOUS MATERIALS FOR ADHESION TYPE APPLICATIONS COMPRISING CALCIUM SULFOALUMINATE (CSA) CEMENT AND LATEX POLYMER." UKnowledge, 2014. http://uknowledge.uky.edu/ce_etds/19.
Full textAbstract:
The objective of this research was to develop high performing polymer modified calcium sulfoaluminate (CSA) cement materials for use in applications requiring superior adhesion characteristics. Little information is available describing interactions of CSA cement containing minor phase tri-calcium aluminate (C3A) with commonly used admixtures. Given the scarcity of information, a basic approach for developing cementitious materials was followed. The basic approach consisted of four tasks: cement design, admixture design, polymer design and testing developed materials. The iterative, time consuming process is necessary for understanding the influence of specific constituent components on overall system behavior. Results from the cement design task suggest calcium sulfate type influences microstructural characteristics and strength development for materials based upon the experimental CSA cement. Results from the admixture design task suggest lithium carbonate and tartaric acid are effective accelerating and retarding admixtures for hydration reactions including reactants yeelimite, calcium sulfate and water. Results from the polymer design task suggest vinyl acetate / ethylene (VAE) dispersible polymer powders (DPP) are compatible with systems containing the experimental CSA cement and other commonly used admixtures. Additionally, results from the polymer design task highlight a method for specifying the ductile behavior of materials containing the experimental CSA cement as majority hydraulic binding agent. Finally, results from the testing of developed materials task suggests adhesion performance for materials containing the experimental CSA cement can be influenced by adjusting the ratio of polymer to hydraulic binding agent in material formulations. Polymer modified CSA cement mortars demonstrated bond strength resulting in substrate failure when cast over porous concrete substrates. Developed mortars demonstrated consistent bonding performance when applied to non-porous substrate materials, metal and glass. Select polymer modified mortars displayed adhesion bond performance such that the glass substrate materials fractured during pull off testing.
41
Dougherty, William R. "Miscibility of vinyl acetate-ethylene copolymers with vinyl chloride-ethylene copolymers /." Diss., 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9935160.
Full text
42
Chen, Po-Tsun, and 陳柏村. "The Impact Toughening of Polystyrene by Ethylene-Vinyl Acetate Copolymer." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/98419770869017245318.
Full textAbstract:
碩士國立成功大學
化學工程學系
88
Toughening of Polystyrene is the major object of this study. Traditionally, PB (Polybutadiene) is used as impact resistant modifier. The Disadvantages of PB are aging, degradation and recycle problems. In place of PB rubber, we use EVA (ethylene-vinyl acetate copolymer) to overcome these problems. However, EVA is incompatible with PS, giving poor adhesion at the interphase. By grafting PS onto EVA backbone, enhancing the mechanical properties and impact resistance of the PS matrix. When addition of 10% EVA, the impact strength increase five times than PS, but modulus decrease five times, too. Morphological studies by scanning electron microscopy revealed crazing is the major toughening mechanism, shear yielding and deformation of EVA phase are the next. The t-BO initiation system has better impact resistance results than BPO initiation system. The clarification of grafting sites on EVA, the effects of reaction condition on grafting efficiency and grafting level, and thermal behavior of graft copolymer (EVA-g-PS) are all discussion in this research. Thermodynamics for EVA/PS/SM ternary solution is used to create a ternary plot, which can be used to simulate the phase states changes in practical reaction and predict when does the phase inversion occur. From the plot, the interaction parameters can be calculated. Phase inversion took places when the volume ratio of two phases reached unity. The molecular weight of EVA affects the time to reach phase inversion. The phase inversion has great influences on mechanical properties of products.
43
Chang, Jian-Sheng, and 張建盛. "Biohydrogen production with sewage sludge immobilized ethylene-vinyl acetate copolymer." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/03568105726393254481.
Full textAbstract:
碩士逢甲大學
化學工程學所
92
Sewage sludge immobilized cells are applied for biohydrogen dark fermentation in our laboratory for many years. The immobilized cell particles were prepared by encapsulates approaches, meanwhile adding of ethylene vinyl acetate copolymer (EVA) to modify the particles physically and chemically. EVA immobilized cells show the advantages of mechanical strength and the stability of hydrogen production activity, which was believed to improve on the EVA immobilized cells. The experimental works were worked on the batch reactor firstly, and then carried out in a continuous fluidized bed bioreactor for hydrogen dark fermentation. The EVA immobilized cells show that the excellent hydrogen production stability during fifteen-repeated batch runs. The optimal operation condition was studied in this investigation. Monod-type kinetic model was fitted well for this data analysis, and shows that the most efficient hydrogen production is at 40 oC and sucrose concentration of 20 gCOD/l. For the continuous fluidized bed bioreactor, changed the sucrose concentrations and hydraulic retention time (HRT) to examine the hydrogen production rates. The results show that sucrose concentration of 20 gCOD/l has better performance. For different particles package, say 5, 10 and 15 % (v/v), the hydrogen production rates order are 10%＞15%＞5% (1.51 l/h/l＞1.21 l/h/l＞0.54 l/h/l). Under the 10% particle package, the various recycle flow rates were tested, the results show that the hydrogen production rates order are 5 l/min＞3 l/ min＞7 l/min (1.57 l/h/l＞1.51 l/h/l＞1.38 l/h/l).
44
Zheng, Ren-Hao, and 鄭人豪. "Dynamic Modeling of High-Pressure Ethylene-Vinyl Acetate Copolymer Autoclave Reactor." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/33535074546716270323.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
90
A mathematical kinetic EVA model is developed to simulate the behavior of multizone, multifeed high-pressure EVA polymerization autoclave reactor. Dynamic mass and energy balance are derived to predict the polymerization rate, monomer concentration, molecular weight(Mw…etc.), and temperature profile with respect to the position in the reactor. The effects of grade transition on the EVA autoclave reactor model are investigated. It is shown that the proposed model is capable of predicting the behavior of EVA autoclaves and can be used for the process design, operating condition optimization, control strategy, and grade transition study of the EVA autoclave reactor.
45
甘子葳. "Modeling of high-pressure ethylene-vinyl acetate copolymer at autoclave reactor." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/17374718142388141080.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
91
For EVA free radical copolymerization, a mathematical model is developed to simulate composition concentration and reaction heat profile in the high-pressure autoclave reactor. Furthermore the model predicts structural and physical properties of production in the reactor outlet. In the model, EVA kinetic model is simplified to homopolymerization by using pseudo kinetic rate constant method, moreover, the reaction mechanism include the long chain branching frequencies. The technique of moments is then used to find the average molecular weight of polymer. Due to nonideal mixing, the reactor is divided into seven reaction zones in sequence. In addition to initiator and monomer feeds, each zone has mutual back-mixing flow. It is shown that the predicting properties of the proposed model agree well with plant model results and actual manufacturing data. In order to predict the properties of production such as Production Rate, Melting Index, Comonomer Weight Percent for seven different grades, we try to obtain the optimal kinetic parameters set for the EVA model. First, the most important reactions that affect the properties of production are determined by quantitative and qualitative analysis, then a three-stage approach is deduced to obtain the optimal kinetic parameters in the model. From different Melting Indexes, two sets of optimal kinetic parameters are found. One applies to three grades of lower Melting Indexes; another applies to four grades of higher Melting Indexes.
46
Li, Chi-Hung, and 李奇鴻. "Preparation and Properties of Olefin Block Copolymer/Ethylene-Vinyl Acetate Copolymer and Composites." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93215513382920393378.
Full textAbstract:
碩士國立宜蘭大學
化學工程與材料工程學系碩士班
101
The study is the investigation on the shape memory behaviors of hollow silica-filled nanocomposites. At first,nano hollow silica was prepared using water/oil emulsion process with tetraethoxysilane as silica source and sodium hydrogen carbonate as a basic catalyst and a blowing agent. The results of scanning electron microscope (SEM) and transmission electron microscopy (TEM) showed the shell thickness of about 20 nm and hollow silica particle size of about 200~500 nm. Then, the olefin block copolymer (Olefin block copolymer, OBC) and ethylene vinyl acetate (Ethylene-vinyl acetate copolymer, EVA) environmentally materials were prepared using OBC-g-MA as a compatibilizer. And then various proportions of EVA, EVA-g-VTEOS, and hollow silica were mixed with each other to produce OBC/EVA, OBC/EVA-g-VTEOS, OBC-g-MA/EVA, OBC-g-MA/EVA-g-VTEOS, OBC/ EVA-g-VTEOS/ silica, and OBC-g-MA/EVA-g-VTEOS/silica blends/composites. The results of Fourier transform infrared spectroscopy (FTIR) suggested that MA grafted on OBC. The results of scanning electron microscope (SEM) confirmed that the modified systems have better dispersion than the unmodified ones. By the differential scanning calorimetry (DSC) test, results showed modified system were slightly higher than the unmodified system on crystallization temperatures. By a DMA (Dynamic Mechanical Analyzer, DMA) analysis the OBC/EVA blends were compatible, but damping peak variations of OBC/EVA-g-VTEOS were not obvious. It is difficult to determine whether compatibility was improved. In a tensile test and the shape memory testing, the tensile strength, and the shape recovery ratio of systems after modification,were higher than those of the unmodified OBC/EVA system. In the shape memory under compression, EVA has good shape fixity and recovery ratio, The shape memory was affected by the pore size and its distribution of the foam. The shape memory effect of modified systems was found to be high, up to 80%.
47
Cheng, Shih-Kai, and 鄭世楷. "Study on the Toughening Poly(Methyl Methacrylate) by Ethylene-Vinyl Acetate Copolymer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/40912424246953605024.
Full textAbstract:
博士國立成功大學
化學工程學系碩博士班
91
In comparison with the other general plastics, poly(methyl methacrylate)(PMMA) has the best optical property and the excellent weathering ability. But the poor impact resistance of PMMA sometimes restricts its application. In this research, by utilizing EVA as the impact modifier, the toughened PMMA sheets are successfully manufactured via casting process. The advantages of EVA are described as follows. First, the VAc segments destroy the PE crystalline, which results in the increasing compatibility of the polymer blend with EVA. Second, without vinyl bonds, the weathering ability of EVA is better than the common rubber. Third, the refractive index of EVA and PMMA at the ambient temperature is close to each other. At last, EVA copolymers are massive produced and the price of EVA is acceptable. Thus, the usage of EVA for toughing PMMA sheet has a lot of profits. After choosing the optimum specification of EVA, in order to realize the morphologies of EVA/PMMA blends, this study examines the phase changes during MMA polymerization. The ternary PMMA/MMA/EVA mixtures are considered to create triangular phase diagram, which responds the phase behaviors during polymerization. The polymer solution undergoes phase separation at the initial stage of the MMA polymerization. Additionally, the phase inversion occurs in the form of spinodal decomposition (SD) after the conversion of MMA reaches 13.8%. With the development of the SD, the coarsening of the second phase makes the combination of EVA phase. As present in the TEM results, the graft copolymer can hinder the combination of the EVA phase and prevent to form the larger particles. Thus, the uniformity of EVA particle size is also available. The graft copolymer can be synthesized by taking tert-butyl peroctoate (t-BO) as the induced initiator during MMA polymerization. In comparison with the melt blends and in situ blends, the toughness is improved as long as the graft copolymer exists in the blend. But the poor transparency of melt blends results in the diminution usage of PMMA. On the other hand, the transparency and toughened PMMA sheet can be successfully manufactured via casting process with the induced initiator, t-BO. After combining the morphologies, mechanical properties and the fracture surface of EVA/PMMA blends, the toughen mechanism can be concluded. After the addition of EVA, the intrinsic brittle PMMA matrix, which the fracture mainly causes by crazing, changes the main fracture mechanism to shear yielding. The yielding region also retards the growth of the craze and absorbs more applied energy. Besides, the graft copolymer increases the adhesion force between the particles and the matrix, which is hindered the cavitation of EVA particles from PMMA matrix. Moreover, a non-linear optical property with the temperature is also observed accidentally in this work.
48
Kalish, Jeffrey P. "Effects of molecular architecture on crystallization behavior of poly(lactic acid) and random ethylene-vinyl acetate copolymers." 2011. https://scholarworks.umass.edu/dissertations/AAI3482709.
Full textAbstract:
The relationship between polymer chain architecture, crystallization behavior, and morphology formation was investigated. The structures formed are highly dependent on chain configuration and crystallization kinetics. Poly(lactic acid) (PLA) and Poly(ethylene-co-vinyl acetate) (EVA) random copolymers were studied. Sample characterization was performed using a variety of techniques, including spectroscopy, scattering, and calorimetry. In PLA, structural differences between alpha' and alpha crystalline phases were analyzed using cryogenic infrared and Raman spectroscopy. Compared to the alpha crystal, the alpha' crystal has slightly looser packing and weaker intermolecular interactions involving carbonyl and methyl functional groups. Simulations in conjunction with Raman scattering analyzed the conformational distortion of the alpha' phase. The conformation of an alpha' chain was determined to have tg't-10/3 conformation with tg't-3/1 units randomly distributed along the chain. Departure of the O-C(alpha); dihedral angle was also confirmed. The structural disorder leads to different thermal properties for alpha' and alpha crystalline forms, which was quantified by measuring the enthalpic change at melting for both crystals (delta H (alpha') = 57 ± 3 J/g and delta H (alpha) = 96 ± 3 J/g). The transformation from alpha' to alpha and the mechanism of order formation in PLA were also elucidated. The relationship between chain configuration of EVA random copolymers and crystallization behavior was established. For three different EVA samples, the distribution of methylene sequences was calculated and compared to a distribution of crystallite sizes formed. This comparison revealed that only a small fraction of the total methylene segments present actually crystallized. Cocrystallization with highly mobile oligomers was explored to enhance the crystallization of EVA copolymers. When blended, EVA28 (28 weight percentage) cocrystallizes with C36H74 n-alkane resulting in faster crystallization kinetics and a higher degree of crystallinity. The observed increase in degree of crystallinity was directly related to the chain configuration. Compositional mapping using Raman spectroscopy provided evidence for oligomer nucleation. The cocrystallization kinetics and morphology of EVA and n-alkane blends was found to depend on the chain length of oligomer. In both systems studied, crystallization kinetics determines the morphologies formed, which are undoubtedly related to the details of molecular architecture.
49
Li, Ching-hsiang, and 李敬翔. "Characteristics of Thermoplastic Polyurethane Elastomer and Ethylene-vinyl Acetate Copolymer Blends and Foams." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9v373r.
Full textAbstract:
碩士逢甲大學
化學工程學系
106
In this study, we investigated characteristics of thermoplastic polyurethane (TPU) elastomer and ethylene-vinyl acetate (EVA) copolymer blends and foams. Foaming reactions of TPU and EVA blend were examined in solution. TPU, 4,4'-Methylenedianiline (MDA) , compatibilizer (cyclohexane-maleic anhydride copolymer, PCH-PMAH) and solvent cyclohexanone were added to the reactor. The reactor was sealed and heated to 120℃ under a magnetic stirring for one day. It is inferred from the results of Fourier Transform Infrared spectrometer (FTIR) and Gel Permeation Chromatography (GPC) that the bonding between MDA and carbamate leads to a chain scission and a decrease in the average molecular weight of TPU. MDA also interacts with maleic anhydride of the compatibilizer. The two reactions compete to each other. In addition, we collected TPUs sample that have been commercialized by several companies and conducted various thermal analyses for them. For rheometrics dynamic analysis (RDA), TPU of the higher G' value can be added to EVA to increase the G' value of the blend so as to increase the melt strength of the blend. TGA and DSC data can be good references when we need to choose a TPU. The foam formed by blending of EVA and TPU was extracted subsequently using two good solvents to facile determining its crosslink density. The result shows that only 70% of EVA was crosslinked. The microphase structure shows that when the foam contains a compatibilizer, the TPU can be more uniformly distributed in the EVA matrix. Key word：Thermoplastic polyurethane elastomer, ethylene-vinyl acetate, blend
50
Tang, WeiJay, and 唐偉傑. "Research on the fiber reinforced water dispersion polyvinyl alcohol / ethylene-vinyl acetate copolymer composites." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/68m8uq.
Full textAbstract:
碩士中國文化大學
化學工程與材料工程學系奈米材料碩士班
100
In this study, prepared by winding fiber composite prepreg material to waterborne dispersion polyvinyl acetate, for the substrate, the glass fiber and carbon fiber reinforced materials to discuss the EVA/PVA winding method used in the feasibility. In addition to comparing different experiments, the percentage of filler addition on the impact of fiber composite materials, but also use laminated sandwich structure prepared by different perspectives and different carbon fiber content of the hybrid fiber composite materials. In addition, when the different parameters in the hot processing, by the mechanical properties, dynamic mechanical properties, thermal properties, physical properties and to investigate the electrical properties of PVA with different properties of fiber composites, and to identify optimal processing conditions parameters. Observed in the SEM to the EVA/PVA attached to the fiber in good condition, particularly in the 500cp viscosity control under the best, show the feasibility of processing, and in the prepreg material to maintain the pressure in the temperature of 90 ℃ at 500 psi specimens produced has the best short be am Inter laminar shear strength(I.L.S.S.), add the filling material kaolin can increase the part of the mechanical and thermal properties, but adding too much viscosity will increase between EVA/PVA, and fiber adhesion conditions deteriorate, resulting in reduced strength. Carbon fiber composite materials can enhance the structural strength, The different layers and can enhance the mechanical properties. Keywords:polyvinyl alcohol/ethylene-vinyl actate copolymer, winding method, prepreg, fiber, composite materials, sandwich structure.