Avaliação da morfologia e das propriedades mecânicas, térmicas e de biodegradação de compostos de PLA/PBAT contendo argila montmorilonita e/ou extensores de cadeia
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Dissertação
Data
2014
Autores
Freitas, A. L. P. L.
Orientador
Souza, Adriana Martinelli Catelli de
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FREITAS, A. L. P. L. Avaliação da morfologia e das propriedades mecânicas, térmicas e de biodegradação de compostos de PLA/PBAT contendo argila montmorilonita e/ou extensores de cadeia. 2014. 93 f. Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário da Fei, São Bernardo do Campo, 2014 Disponível em: . Acesso em: 21 maio 2014.
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Palavras-chave
Polímeros-Propriedades mecânicas,Compósitos poliméricos,Nanocompósitos
Resumo
O presente trabalho apresenta a avaliação da morfologia e das propriedades mecânicas, térmicas e de biodegradação de compostos de PLA/PBAT (ECOVIO® F Blend C2224) contendo argila montmorilonita (MMT) (Cloisite® 20A) e/ou extensores de cadeia (Joncryl® extrusora corrotacional de dupla rosca. Os grânulos processados foram avaliados, injetados e prensados em corpos de prova. A morfologia dos compostos avaliados foi verificada através da microscopia eletrônica de varredura (MEV) utilizando-se superfícies de fratura de corpos de prova provenientes dos ensaios de impacto. O grau de esfoliação da argila na matriz polimérica foi comprovado pelos ensaio de difração de raios X (DRX) e a efetividade dos extensores de cadeia por índice de fluidez (IF). As propriedades mecânicas foram verificadas através de ensaios de resistência à tração, flexão e impacto, e as propriedades térmicas a partir de temperatura de deflexão térmica (HDT). Para o ensaio de biodegradação corpos de provas foram enterrados em solo simulado com temperatura e umidade controladas, e de tempos em tempos analisou-se a perda de massa dos mesmos. A análise morfológica indicou que as blendas obtidas estão em forma de dispersão de gotas. Observou-se que para todas as composições analisadas houve segregação da fase dispersa para o centro do corpo de prova injetado. A argila MMT favoreceu a coalescência das partículas no centro dos corpos de prova. Os resultados dos ensaios de raios X indicaram que o tipo de processamento para a obtenção dos corpos de prova afetou a esfoliação da argila na matriz das blendas: a argila apresentou-se esfoliada em corpos de prova prensados e intercalada em corpos de prova injetados. A adição de MMT resultou num decréscimo das propriedades mecânicas. Todavia, a adição de MMT estimulou a biodegradação do material, além de retardar a sua degradação térmica. Os extensores de cadeia promovem recuperação de parte das propriedades mecânicas em flexão e impacto perdidas com o processamento e com a inclusão da argila e retardaram a degradação térmica dos compostos. Dentre os exgtensores o de estrutura ramificada (Joncryl® 4368) mostrou-se mais eficiente que o de estrutura linear (Joncryl® 4300) no aumento da massa molar.
This thesis presents the evaluation of the morphology, as well as mechanical, thermal and biodegradation properties of PLA/PBAT (Ecovio® F Blend C2224) compounds containing montmorillonite clay (MMT) (Cloisite® 20A) and/or chain extenders (Joncryl® 4368 and 4300). Processing was carried out by melt mixing by means of a co-rotating twin-screw extruder. The processed granules were evaluated, injected and pressed into specimens. The morphology of the evaluated compounds was checked via scanning electron microscopy (SEM), using surfaces of fractured Charpy impact test specimens. Exfoliation of the clay in the polymer matrix was confirmed by X-ray diffraction (XRD) and the effectiveness of the chain extenders by melt flow rate (MFR). The mechanical properties were verified by tensile, flexural and impact strength tests; thermal properties by differential scanning calorimetry (DSC), thermogravimetry (TGA) and heat deflection temperature analysis (HDT). For biodegradation, specimens were buried under simulated soil with controlled temperature and humidity, and their mass loss was analyzed on a frequent basis. Morphological analysis revealed the presence of a droplet-like dispersed phase. All investigations showed segregation of the dispersed phase to the center of the injected specimens. MMT clay favored coalescence of particles in the center of the specimens. XRD tests indicated that the type of processing affected exfoliation of the clay matrix in the blends: in the pressed specimens the clay showed to be exfoliated and intercalated in the injected specimens. Addition of MMT resulted in a decrease in mechanical properties. However, addition of MMT stimulated biodegradation of the material and retarded its thermal degradation. The chain extenders partially promoted recovery of the mechanical properties in flexural and impact that had been lost due to processing and incorporation of the clay, in addition to slowing down the thermal degradation of the compounds. Furthermore, the extenders of the branched structure (Joncryl ® 4368) were more efficient than the linear structure (Joncryl ® 4300) in increasing molar weight.
This thesis presents the evaluation of the morphology, as well as mechanical, thermal and biodegradation properties of PLA/PBAT (Ecovio® F Blend C2224) compounds containing montmorillonite clay (MMT) (Cloisite® 20A) and/or chain extenders (Joncryl® 4368 and 4300). Processing was carried out by melt mixing by means of a co-rotating twin-screw extruder. The processed granules were evaluated, injected and pressed into specimens. The morphology of the evaluated compounds was checked via scanning electron microscopy (SEM), using surfaces of fractured Charpy impact test specimens. Exfoliation of the clay in the polymer matrix was confirmed by X-ray diffraction (XRD) and the effectiveness of the chain extenders by melt flow rate (MFR). The mechanical properties were verified by tensile, flexural and impact strength tests; thermal properties by differential scanning calorimetry (DSC), thermogravimetry (TGA) and heat deflection temperature analysis (HDT). For biodegradation, specimens were buried under simulated soil with controlled temperature and humidity, and their mass loss was analyzed on a frequent basis. Morphological analysis revealed the presence of a droplet-like dispersed phase. All investigations showed segregation of the dispersed phase to the center of the injected specimens. MMT clay favored coalescence of particles in the center of the specimens. XRD tests indicated that the type of processing affected exfoliation of the clay matrix in the blends: in the pressed specimens the clay showed to be exfoliated and intercalated in the injected specimens. Addition of MMT resulted in a decrease in mechanical properties. However, addition of MMT stimulated biodegradation of the material and retarded its thermal degradation. The chain extenders partially promoted recovery of the mechanical properties in flexural and impact that had been lost due to processing and incorporation of the clay, in addition to slowing down the thermal degradation of the compounds. Furthermore, the extenders of the branched structure (Joncryl ® 4368) were more efficient than the linear structure (Joncryl ® 4300) in increasing molar weight.