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Master's Dissertation
DOI
10.11606/D.3.2011.tde-26032012-113625
Document
Author
Full name
Gustavo Russo Blazek
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2011
Supervisor
Committee
Wang, Shu Hui (President)
Drumond, Walker Soares
Fernandes, Elizabeth Grillo
Title in Portuguese
Estudo da blenda poli(3-hidroxibutirato) / poli(etileno glicol).
Keywords in Portuguese
Blendas poliméricas
Poli(3-hidroxibutirato)
Polímeros biodegradáveis
Abstract in Portuguese
Esse projeto visa a melhoria das propriedades mecânicas e de processabilidade do Poli(3-hidroxibutirato) (PHB) para futuras aplicações. Foram preparados filmes de blendas de PHB por dissolução em clorofórmio. Poli(etileno glicol), com massa molar de 300 (PEG) ou 4.000.000 g mol-1 (PEO), foi misturado em proporções de 5 a 30 % em massa e análises termogravimétricas (TG), de calorimetria diferencial exploratória (DSC) e ensaios dinâmico-mecânicos (DMTA) foram realizadas para avaliar a miscibilidade da blenda. Foram também analisados filmes recém-preparados e filmes envelhecidos, para avaliar o avanço da cristalização e consequente alteração das propriedades dos filmes com o passar do tempo. Para isso foram feitas comparações visuais de imagens microscópicas da morfologia das blendas, obtidas através de microscopia eletrônica de varredura (MEV). As blendas foram analisadas quanto ao grau de cristalinidade através de análise calorimétrica (DSC) e de difratometria de raio-X. As curvas de DSC mostram uma redução da Tm do PHB com a adição de PEG e PEO, o que indica uma forte interação entre os polímeros. As análises de TG mostram uma etapa principal de degradação, evidenciando a miscibilidade entre os polímeros. A TG também mostra uma sensível redução na temperatura de degradação do PHB para concentrações acima de 10 % em PEG, o que é indesejável. Através do MEV nota-se que existe também uma segregação de fases que aumenta com o tempo de estocagem do material, levando à recristalização do PHB e sua consequente fragilização. A difração de raios-X nos mostra que a adição de PEG e PEO ao PHB traz uma redução considerável para a cristalinidade do sistema, e que o aumento de 5 % para 30 % no teor de PEG é responsável por apenas uma pequena redução na cristalinidade, mas uma considerável redução na recristalização sofrida pela blenda com o tempo de estocagem. As análises de DMTA mostram que as blendas possuem módulo de armazenamento similar ao de polímeros flexíveis, evidenciando uma efetiva tenacificação do PHB. Amostras utilizando PEO apresentam maior rigidez do que as amostras contendo PEG.
Title in English
Poly(3-hydroxybutyrate) / poly(ethylene oxide) blend study.
Keywords in English
Biodegradable polymers
Polimeric blends
Poly(3-hydroxybutyrate)
Abstract in English
This project aims the enhancement of both processability and mechanical properties of poly(3-hydroxybutyrate) (PHB) for future applications. Films of blends of PHB and poly(ethylene oxide) were prepared by chloroform solution casting and evaporation. Poly(ethylene oxide) having molar mass of 4,000,000 (PEO) or 300 g.mol-1 (PEG) was blended in proportion of 5 to 30 wt %, Thermogravimetric Analysis (TG), Differential Scanning Calorimetry (DSC) and Dynamic-Mechanic Analysis (DMTA) were performed in order to evaluate the miscibility of the blends. As-cast and aged films were also compared in order to analyze the crystallization progress and the consequent changes in the blends properties due to the aging process. For this, visual comparison was drawn between microscopy pictures obtained through scanning electron microscopy (SEM). The blends have their crystallinity degree determined by analyzing their X-ray diffraction curves. The DSC curves show a reduction at the PHBs Tm as the mass percentage of PEG increases, indicating a strong interaction in between the polymers. The TG and DTG analyses reveal a single main degradation step, what denotes miscibility in between the polymers. The TG also shows a considerable reduction of the PHBs degrading temperature for PEG concentrations over 10 %, which is undesirable. Through SEM one can note a phase segregation that increases with storaging time, leading to further crystallization of PHB and its subsequent enbrittlement. The X-ray diffraction curves show that the PEG and PEO bring a considerable crystallinity reduction to the system, and that the increasing of PEG content from 5 to 30% has only a minor effect per se, though also a considerable reduction of the perfection undergone by the system with storage time. The DMTA shows that the blends have a storage modulus similar to the one of flexible polimers, hence showing an effective PHB toughening. Samples containing PEO are more rigid than those containing PEG.
 
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Publishing Date
2012-04-04
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • DRUMOND, W. S., et al. MISCIBILITY AND THERMAL PROPERTIES OF BLENDS OF POLY(3-HYDROXYBUTYRATE) ANDPOLYETHYLENE OXIDE. In XI International Macromolecular Colloquium /6th International Symposium on Natural Polymers and Composites, GRAMADO, 2007. PROGRAM AND PROCEEDINGS OF XI International Macromolecular Colloquium /6th International Symposium on Natural Polymers and Composites.PORTO ALEGRE : UFRGS, 2007. Abstract.
  • DRUMOND, Walker Soares, et al. MISCIBILITY AND THERMAL PROPERTIES OF BLENDS OF POLY(3-HYDROXYBUTYRATE) AND POLYETHYLENE OXIDE. In XI International Macromolecular Colloquium /6th International Symposium on Natural Polymers and Composites, GRAMADO, 2007. XI International Macromolecular Colloquium /6th International Symposium on Natural Polymers and Composites.PORTO ALEGRE : UFRGS, 2007.
  • SHIROMA E, et al. Poly(3-hydroxybutyrate) toughening by blending with poly(ethylene glycol). In 41st international symposium on macromolecules, rio de janeiro, 2006. macro2006-41st international symposium on macromolecules.sao carlos : abpol, 2006. Abstract.
  • SHIROMA E, et al. POLY(3-HYDROXYBUTYRATE)THOUGHENING BY BLENDING WITH POLY(ETHYLENE GLYCOL). In 41ST INTERNATIONAL SYMPOSIUM ON MACROMOLECULES, RIO DE JANEIRO, 2006. WORLD POLYMER CONGRESS PROGRAM.SAO CARLOS : ABPOL, 2006. Abstract.
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