Estudo da influência dos teores de fibra, agente compatibilizante e tamanho de fibra nas propriedades de compósitos de polipropileno com fibra de bambu
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Tipo de produção
Dissertação
Data
2011
Autores
Caranti, Lilian Roberta Arisa
Orientador
Bonse, B. C.
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CARANTI, Lilian Roberta Arisa. Estudo da influência dos teores de fibra, agente compatibilizante e tamanho de fibra nas propriedades de compósitos de polipropileno com fibra de bambu. 2011. 189 f. Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário da Fei, São Bernardo do Campo, 2011
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Compósitos poliméricos,Polipropileno
Resumo
A necessidade contemporânea de preservação ecológica desafia os campos da ciência a desenvolverem materiais e processos ambientalmente sustentáveis. A pesquisa de compósitos reforçados com fibras vegetais celulósicas busca suprir esta necessidade. Comparativamente, o biocompósito requer menos energia para produção do que material homólogo reforçado com fibras sintéticas. Ademais, fibras vegetais são biodegradáveis e procedentes de fontes renováveis.
O presente trabalho deu ênfase ao estudo dos comportamentos mecânico e térmico do compósito de uma matriz termoplástica de polipropileno com fibra de bambu (Phyllostachys Edulis). A adesão interfacial entre os dois materiais foi promovida por meio de agente compatibilizante polipropileno enxertado com anidrido maleico PP-g-MA. Utilizou-se planejamento experimental fatorial 23 por meio do estudo de 8 formulações preparadas com variações quanto ao tamanho médio de fibra (nível inferior = 0,94 mm e nível superior = 2,19 mm), teor de fibra (20% e 40% em massa) e agente compatibilizante PP-g-MA (1% e 4% em massa). O comportamento mecânico do compósito foi avaliado por meio de ensaios de tração, flexão, impacto e fadiga. O comportamento térmico por meio de ensaio de deflexão por temperatura. Na investigação morfológica utilizou-se microscopia óptica. A cristalinidade foi medida por difração de raios X e as superfícies fraturadas foram observadas e analisadas por meio de microscopia eletrônica de varredura. A análise estatística de regressão múltipla avaliou os efeitos de interação das variáveis. O nível de significância adotado foi 0,05 com intervalo de confiança de 95%. O ponto ótimo foi obtido por curvas de contorno. A resistência à tração, o módulo em tração, a resistência à flexão, o módulo em flexão, a vida em fadiga e a temperatura de deflexão térmica do compósito aumentaram significativamente com a incorporação de 40% de fibra de bambu. O alongamento à ruptura e a tenacidade diminuíram com o aumento do teor de fibras. A adição do agente compatibilizante influenciou positivamente a resistência à tração, a deformação na ruptura, a tenacidade, a resistência à flexão, o módulo em flexão, a vida em fadiga e a resistência ao impacto do material. O aumento do tamanho da fibra foi signifcativo e positivo apenas nas propriedades mecânicas tensão máxima em tração e módulo em flexão. O aumento do teor de fibra de bambu acarretou queda no grau de cristalinidade do compósito, o grau de cristalinidade foi superior na direção longitudinal comparado à direção transversal ao fluxo de injeção. Fibras de bambu, auxiliadas por agente compatibilizante, podem ser utilizadas com êxito na manufatura de compósitos poliméricos reforçados com fibra, exceto para aplicações que requeiram alta resistência ao impacto.
The contemporary need for ecological preservation challenges the fields of science to develop environmentally sustainable materials and processes. Research on composites reinforced with natural cellulosic fibres seeks to meet that need. Comparatively speaking, manufacture of biocomposites requires less energy than homologous materials reinforced with synthetic fibres. Furthermore, natural fibres are biodegradable and come from renewable sources. The present research work aimed an investigation on the mechanical and thermal behaviour of a composite comprising a polypropylene thermoplastic matrix and bamboo fibres (Phyllostachys Edulis). Interfacial adhesion between the two materials was achieved by the addition of compatibilizer maleic anhydride grafted polypropylene PP-g-MA. A 23 experimental design was employed and 8 compositions were prepared by varying the average fibre size (lower level = 0.94 mm and upper level = 2.19 mm), fibre content (20 and 40 wt%) and compatibilizer PP-g-MA content (1 and 4 wt%). The mechanical behaviour of the composites was studied by carrying out tensile, flexural, impact and fatigue tests. Thermal behaviour was investigated by heat deflection temperature tests. Morphological investigation employed optical microscopy. Crystallinity was measured by means of X Ray diffraction and fractured surfaces were observed and analyzed by scanning electron microscopy. Multiple regression statistical analysis was performed to interpret interaction effects of the variables. The significance level was set at 0.05 and the confidence interval was 95%. Optimal design was obtained by contour plots. The tensile strength, tensile modulus, flexural stress, flexural modulus, fatigue life and heat deflection temperature of the composites increased considerably by incorporating 40 weight% bamboo fibre. Elongation at break and toughness decreased at increasing fibre content. The addition of compatibilizer PP-g-MA affected positively tensile strength, elongation at break, toughness, flexural stress, flexural modulus, fatigue life and impact strength of the material. The increase in the fibre size was only effective in improving mechanical properties such as maximum tensile strength and flexural modulus. The increase in the bamboo fibre content resulted in loss of crystallinity. The measured crystallinity was higher longitudinally than transversely to the injection molding flow. Bamboo fibres, with the aid of compatibilizer, can be successfully used for manufacturing of fibre-reinforced polymer composites, except for applications that require high impact strength.
The contemporary need for ecological preservation challenges the fields of science to develop environmentally sustainable materials and processes. Research on composites reinforced with natural cellulosic fibres seeks to meet that need. Comparatively speaking, manufacture of biocomposites requires less energy than homologous materials reinforced with synthetic fibres. Furthermore, natural fibres are biodegradable and come from renewable sources. The present research work aimed an investigation on the mechanical and thermal behaviour of a composite comprising a polypropylene thermoplastic matrix and bamboo fibres (Phyllostachys Edulis). Interfacial adhesion between the two materials was achieved by the addition of compatibilizer maleic anhydride grafted polypropylene PP-g-MA. A 23 experimental design was employed and 8 compositions were prepared by varying the average fibre size (lower level = 0.94 mm and upper level = 2.19 mm), fibre content (20 and 40 wt%) and compatibilizer PP-g-MA content (1 and 4 wt%). The mechanical behaviour of the composites was studied by carrying out tensile, flexural, impact and fatigue tests. Thermal behaviour was investigated by heat deflection temperature tests. Morphological investigation employed optical microscopy. Crystallinity was measured by means of X Ray diffraction and fractured surfaces were observed and analyzed by scanning electron microscopy. Multiple regression statistical analysis was performed to interpret interaction effects of the variables. The significance level was set at 0.05 and the confidence interval was 95%. Optimal design was obtained by contour plots. The tensile strength, tensile modulus, flexural stress, flexural modulus, fatigue life and heat deflection temperature of the composites increased considerably by incorporating 40 weight% bamboo fibre. Elongation at break and toughness decreased at increasing fibre content. The addition of compatibilizer PP-g-MA affected positively tensile strength, elongation at break, toughness, flexural stress, flexural modulus, fatigue life and impact strength of the material. The increase in the fibre size was only effective in improving mechanical properties such as maximum tensile strength and flexural modulus. The increase in the bamboo fibre content resulted in loss of crystallinity. The measured crystallinity was higher longitudinally than transversely to the injection molding flow. Bamboo fibres, with the aid of compatibilizer, can be successfully used for manufacturing of fibre-reinforced polymer composites, except for applications that require high impact strength.