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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Microstructural analysis of polyethylenes and their blends and copolymers

Minick, Jill Suzanne January 1995 (has links)
No description available.
22

Characterization of Polymorphic and Blended Drugs by Physical-analytical Properties

Munigeti, Rajgopal January 2007 (has links)
No description available.
23

Investigative study of Biopolymer contamination in conventional recycling systems

Kuzhanthaivelu, Gauthaman January 2018 (has links)
The recycling industry which is efficiently functioning now has technical expertise, contented consumers, and resource availability and capital contributors. The potential inflow of new material into this existing system should be able to fulfill all the needs of the stakeholders involved in it. With most of the polymer wastes received from the polyethylene (PE) and polyethylene terephthalate (PET), they are available in abundant crossing the threshold quantity (Cornell, 2007) needed for the recycling process to be carried for every single polymer starting from the individual source separation till the granulation of pellets with active investment for the potential expectancy of returns in the recycling market targeting suitable consumers. Unlike other polymers like polyvinyl chloride and polypropylene (PP), biopolymers fail to fulfill the necessary criteria of being in threshold quantity to carry out the recycling process. With the very small inflow of biopolymers in the recycling industry, standalone recycling units for the same is not highly performed and appreciated. In addition to this, there are possible means and ways of the biopolymers getting infused into the conventional petrochemical polymers either through the mis-throws in manual sorting or in automated sorting. Though the studies so far don't have any substantial threatening effect over the biopolymer infusion, still it has its adversity affecting the industry by other means. The volumes of biopolymers are presently small and contamination of biopolymer in the plastic waste stream is presently not a problem. However, with increasing volumes of biopolymers, this can be a problem. Contamination could then be a future problem. This study investigates that problem and checks the truth to the claims of biopolymer infusion in the conventional post-consumer recycling systems affecting the quality of the recyclates. In order to investigate this, a biodegradable biopolymer (TPS & PHA) will be mixed into a conventional polymer (PE, PP, PET) at various percentages. The mechanical and thermal properties are then measured as a function of the percentage biopolymer. In a second part of the project, the blend of conventional plastics and bioplastic is conditioned in humidity in order to simulate what will happen to a conventional polymer that has been contaminated with a biopolymer in a humid climate.
24

Investigative study of Biopolymer contamination in conventional recycling systems

Kuzhanthaivelu, Gauthaman January 2018 (has links)
The recycling industry which is efficiently functioning now has technical expertise, contented consumers, and resource availability and capital contributors. The potential inflow of new material into this existing system should be able to fulfill all the needs of the stakeholders involved in it. With most of the polymer wastes received from the polyethylene (PE) and polyethylene terephthalate (PET), they are available in abundant crossing the threshold quantity (Cornell, 2007) needed for the recycling process to be carried for every single polymer starting from the individual source separation till the granulation of pellets with active investment for the potential expectancy of returns in the recycling market targeting suitable consumers. Unlike other polymers like polyvinyl chloride and polypropylene (PP), biopolymers fail to fulfill the necessary criteria of being in threshold quantity to carry out the recycling process. With the very small inflow of biopolymers in the recycling industry, standalone recycling units for the same is not highly performed and appreciated. In addition to this, there are possible means and ways of the biopolymers getting infused into the conventional petrochemical polymers either through the mis-throws in manual sorting or in automated sorting. Though the studies so far don't have any substantial threatening effect over the biopolymer infusion, still it has its adversity affecting the industry by other means. The volumes of biopolymers are presently small and contamination of biopolymer in the plastic waste stream is presently not a problem. However, with increasing volumes of biopolymers, this can be a problem. Contamination could then be a future problem. This study investigates that problem and checks the truth to the claims of biopolymer infusion in the conventional post-consumer recycling systems affecting the quality of the recyclates. In order to investigate this, a biodegradable biopolymer (TPS & PHA) will be mixed into a conventional polymer (PE, PP, PET) at various percentages. The mechanical and thermal properties are then measured as a function of the percentage biopolymer. In a second part of the project, the blend of conventional plastics and bioplastic is conditioned in humidity in order to simulate what will happen to a conventional polymer that has been contaminated with a biopolymer in a humid climate.
25

Studies In Low Density Polyethylene-Starch Blends

Reddy, Prasad A 01 1900 (has links) (PDF)
No description available.
26

The structure and kinetics of formation of grafted polymer layers

Clarke, Christopher John January 1994 (has links)
No description available.
27

The dynamics of cricket ball impacts and the effect of pitch construction

Carre, Matthew Jon January 2000 (has links)
No description available.
28

Obtenção e caracterização de misturas do polímero biodegradável P[3HB] e seu copolímero P[3HB-co-3HV] com elastômeros. / Obtention and characterization of polymer blends based on P[3HB] and its copolymer P[3HB-co-3HV] with elastomers.

Calvão, Patrícia Schmid 15 September 2009 (has links)
Neste trabalho foi desenvolvido um estudo com o poliéster biodegradável P[3HB] (poli[R-3-hidroxibutirato]) e seu copolímero P[3HB-co-3HV] (poli[R-3-hidroxibutirato-co-3- hidroxivalerato]). Esses materiais são conhecidos por seu grande potencial de biodegradabilidade, porém sua utilização pela indústria ainda é limitada em função de seu baixo desempenho mecânico. Visando a tenacificação desses materiais, optou-se por misturá-los com os elastômeros EPDM (terpolímero de etileno-propileno-dieno) e PVB (Poli(vinil butiral)). Foram estudados quatro grupos de blendas: P[3HB]/EPDM e P[3HB-co- 3HV]/EPDM processados em misturadores internos e posteriormente prensadas em filmes; P[3HB]/EPDM e P[3HB]/PVB extrudados e posteriormente injetados. As blendas foram obtidas nas concentrações de 10, 20 e 30% em peso de elastômeros. Inicialmente, estudou-se efeito da incorporação de elastômeros na cristalinidade, estrutura cristalina, propriedades térmicas e dinâmico-mecânicas das matrizes, e o efeito do tipo de processamento utilizado. Observou-se que a adição dos elastômeros às matrizes semicristalinas aumentou a nucleação de esferulitos, resultando em um aumento da cristalinidade das mesmas. O PVB apresentou um efeito plastificante na estrutura do PHB. Os filmes apresentaram uma degradação térmica maior que as amostras injetadas, resultando em uma cristalização mais lenta e um grau de cristalinidade maior. Em um outro estudo, avaliou-se a morfologia, tensão interfacial, comportamento reológico, propriedades mecânicas e a biodegradabilidade das amostras estudadas. Foi observada uma morfologia de dispersão de gotas para todas as misturas, exceto para a mistura P[3HB]/EPDM obtida por injeção que apresentou um certo grau de co-continuidade. No caso das misturas injetadas foi visto que o fator que parece influenciar mais fortemente em sua morfologia final são as razões de viscosidade observadas entre a matriz e a fase dispersa das mesmas. A adição de elastômeros aumentou a resistência ao impacto do P[3HB], principalmente no caso da mistura P[3HB]/EPDM, o que pode estar relacionado à morfologia co-contínua observada nesta blenda. A incorporação dos elastômeros resultou em uma redução do módulo de elasticidade e da resistência à tração do P[3HB], e aumento do alongamento, principalmente no caso da mistura com PVB. Foi visto que a biodegradação do P[3HB] e P[3HB-co-3HV] aumentou com a adição de elastômeros, devido à morfologia de dispersão e a diminuição do tamanho dos esferulitos que aumentam a área interfacial para a ação das enzimas, facilitando a biodegradação. / In this work a study with the biodegradable polyester P[3HB] (poly[R-3- hydroxybutyrate]) and its copolymer P[3HB-co-3HV] (poly[R-3-hydroxybutyrate-co-3- hydroxyvalerate]) was conducted. These materials are known for their high biodegradability but their use is still limited because of their poor mechanical properties. In order to improve these properties it was chosen to blend these biodegradable polymers with EPDM (Ethylene propylene diene monomer) and PVB (Polyvinyl butyral). Four groups of blends were obtained: P[3HB]/EPDM and P[3HB-co-3HV]/EPDM blends were prepared using an internal mixer and then compressed molded; P[3HB]/PVB and P[3HB]/EPDM blends were prepared using an extruder and further injected. The blend concentrations ranged from 10 to 30 wt. % of the rubbery phase. Initially, the effect of rubber type on the crystallinity, the crystalline structure, thermal and dynamic-mechanical properties of the matrices and the effect of processing method to obtain the blends were investigated. The addition of elastomers on P[3HB] (and P[3HB-co- 3HV]) increases the nucleation, resulting in an increase of matrix crystallinity. PVB showed a plasticizing effect on the P[3HB] structure. Film samples showed a higher thermal degradation than injected ones, resulting in a slower crystallization and higher crystallinity. The morphology, interfacial tension, rheological behavior, mechanical properties (tensile and impact) and biodegradability of samples were also studied. A droplet dispersion morphology type was obtained for all the blends except for P[3HB]/EPDM injected samples which presented some extent of degree of continuity. The experimental results indicated that the final morphology observed for the blends was controlled by the viscosity ratio between the matrix and dispersed phase. Elastomer addition increased P[3HB] impact strength mainly for P[3HB]/EPDM blends, probably due to its co-continuous morphology. Moreover, elastomer incorporation resulted in a decrease of P[3HB] elastic moduli and tensile strength and increase of elongation of break, mainly for P[3HB]/PVB blends. It was observed that P[3HB] and P[3HB-co-3HV] biodegradation increased with elastomer addition due to the droplet dispersion morphology and decrease of spherulites size witch causes an increase of interfacial area for enzymes, facilitating biodegradation.
29

Obtenção e caracterização de misturas do polímero biodegradável P[3HB] e seu copolímero P[3HB-co-3HV] com elastômeros. / Obtention and characterization of polymer blends based on P[3HB] and its copolymer P[3HB-co-3HV] with elastomers.

Patrícia Schmid Calvão 15 September 2009 (has links)
Neste trabalho foi desenvolvido um estudo com o poliéster biodegradável P[3HB] (poli[R-3-hidroxibutirato]) e seu copolímero P[3HB-co-3HV] (poli[R-3-hidroxibutirato-co-3- hidroxivalerato]). Esses materiais são conhecidos por seu grande potencial de biodegradabilidade, porém sua utilização pela indústria ainda é limitada em função de seu baixo desempenho mecânico. Visando a tenacificação desses materiais, optou-se por misturá-los com os elastômeros EPDM (terpolímero de etileno-propileno-dieno) e PVB (Poli(vinil butiral)). Foram estudados quatro grupos de blendas: P[3HB]/EPDM e P[3HB-co- 3HV]/EPDM processados em misturadores internos e posteriormente prensadas em filmes; P[3HB]/EPDM e P[3HB]/PVB extrudados e posteriormente injetados. As blendas foram obtidas nas concentrações de 10, 20 e 30% em peso de elastômeros. Inicialmente, estudou-se efeito da incorporação de elastômeros na cristalinidade, estrutura cristalina, propriedades térmicas e dinâmico-mecânicas das matrizes, e o efeito do tipo de processamento utilizado. Observou-se que a adição dos elastômeros às matrizes semicristalinas aumentou a nucleação de esferulitos, resultando em um aumento da cristalinidade das mesmas. O PVB apresentou um efeito plastificante na estrutura do PHB. Os filmes apresentaram uma degradação térmica maior que as amostras injetadas, resultando em uma cristalização mais lenta e um grau de cristalinidade maior. Em um outro estudo, avaliou-se a morfologia, tensão interfacial, comportamento reológico, propriedades mecânicas e a biodegradabilidade das amostras estudadas. Foi observada uma morfologia de dispersão de gotas para todas as misturas, exceto para a mistura P[3HB]/EPDM obtida por injeção que apresentou um certo grau de co-continuidade. No caso das misturas injetadas foi visto que o fator que parece influenciar mais fortemente em sua morfologia final são as razões de viscosidade observadas entre a matriz e a fase dispersa das mesmas. A adição de elastômeros aumentou a resistência ao impacto do P[3HB], principalmente no caso da mistura P[3HB]/EPDM, o que pode estar relacionado à morfologia co-contínua observada nesta blenda. A incorporação dos elastômeros resultou em uma redução do módulo de elasticidade e da resistência à tração do P[3HB], e aumento do alongamento, principalmente no caso da mistura com PVB. Foi visto que a biodegradação do P[3HB] e P[3HB-co-3HV] aumentou com a adição de elastômeros, devido à morfologia de dispersão e a diminuição do tamanho dos esferulitos que aumentam a área interfacial para a ação das enzimas, facilitando a biodegradação. / In this work a study with the biodegradable polyester P[3HB] (poly[R-3- hydroxybutyrate]) and its copolymer P[3HB-co-3HV] (poly[R-3-hydroxybutyrate-co-3- hydroxyvalerate]) was conducted. These materials are known for their high biodegradability but their use is still limited because of their poor mechanical properties. In order to improve these properties it was chosen to blend these biodegradable polymers with EPDM (Ethylene propylene diene monomer) and PVB (Polyvinyl butyral). Four groups of blends were obtained: P[3HB]/EPDM and P[3HB-co-3HV]/EPDM blends were prepared using an internal mixer and then compressed molded; P[3HB]/PVB and P[3HB]/EPDM blends were prepared using an extruder and further injected. The blend concentrations ranged from 10 to 30 wt. % of the rubbery phase. Initially, the effect of rubber type on the crystallinity, the crystalline structure, thermal and dynamic-mechanical properties of the matrices and the effect of processing method to obtain the blends were investigated. The addition of elastomers on P[3HB] (and P[3HB-co- 3HV]) increases the nucleation, resulting in an increase of matrix crystallinity. PVB showed a plasticizing effect on the P[3HB] structure. Film samples showed a higher thermal degradation than injected ones, resulting in a slower crystallization and higher crystallinity. The morphology, interfacial tension, rheological behavior, mechanical properties (tensile and impact) and biodegradability of samples were also studied. A droplet dispersion morphology type was obtained for all the blends except for P[3HB]/EPDM injected samples which presented some extent of degree of continuity. The experimental results indicated that the final morphology observed for the blends was controlled by the viscosity ratio between the matrix and dispersed phase. Elastomer addition increased P[3HB] impact strength mainly for P[3HB]/EPDM blends, probably due to its co-continuous morphology. Moreover, elastomer incorporation resulted in a decrease of P[3HB] elastic moduli and tensile strength and increase of elongation of break, mainly for P[3HB]/PVB blends. It was observed that P[3HB] and P[3HB-co-3HV] biodegradation increased with elastomer addition due to the droplet dispersion morphology and decrease of spherulites size witch causes an increase of interfacial area for enzymes, facilitating biodegradation.
30

Using Hydrogen-Bonding Interactions to Control the Peptide Miscibility and Secondary Structures

Lu, Yi-syuan 07 August 2012 (has links)
In this study we synthesized poly(tyrosine) (PTyr) through living ring-opening polymerization of £\-amino acid-N-carboxyanhydride and then blended with poly(4-vinyl pyridine) (P4VP) homopolymer in N, N-dimethylformamide (DMF) and methanol solutions to control the miscibility behavior and the secondary structures of poly(tyrosine). Infrared spectrum analysis suggests that the mixture of PTyr/P4VP possesses strong hydrogen-bonding interaction between the hydroxyl group of PTyr and the pyridine group of P4VP. DSC analyses indicate that these PTyr/P4VP complexes from methanol solution always have higher glass transition temperatures than the corresponding PTyr/P4VP miscible blends obtained from DMF solution. We proposed that the polymer chain behavior of PTyr/P4VP blend from DMF solution is the separated random coil and thus the PTyr chain possesses the random coil secondary structure after solvent evaporation. However, by increasing the hydrogen bonding for PTyr/P4VP complex from methanol solution, inter-polymer complex aggregate is proposed and the corresponding chain behavior enhances the intermolecular hydrogen bonding interaction of PTyr with P4VP that results in the £]-sheet conformation based on Fourier transforms infrared (FTIR), solid state nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray diffraction analyses.

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