Resumo: O presente trabalho busca avaliar o comportamento de compósitos que contêm em sua formulação um biopolímero originário de indústrias da agricultura sustentável. O biopolímero selecionado, poli(ácido lático), (PLA) e um polímero termoplástico (poliuretano), (TPU), foram misturados a fibras naturais (madeira e coco). Em um primeiro momento, foram preparadas formulações contendo 10, 20 e 30% em massa de fibra vegetal em relação à blenda de PLA-TPU (na proporção de 70/30% em massa). Em um segundo momento, manteve-se a mesma proporção em massa de fibra vegetal em relação à blenda de PLA-TPU, porém foram adicionados 5% em massa de anidrido maleico. Na sequência, as formulações foram avaliadas através de caracterizações físico-mecânicas, térmicas e microscópica. De um modo geral, as análises mostraram evidências bastante conclusivas sobre a baixa adesão interfacial entre a blenda polimérica e as fibras vegetais. Deve-se salientar a fraca atuação do anidrido maleico como agente de acoplamento, haja vista que as formulações que o continham não apresentaram melhoras em suas propriedades. Portanto, os resultados indicam que os biocompósitos formulados possam atender à necessidade de nichos específicos de mercados populares, como o de decoração, os quais não demandam alto desempenho de seus produtos, viabilizando o uso de fibras vegetais devido à redução de custo do compósito final. Palavras-chave: Biopolímero, poli(ácido lático), compósitos poliméricos, fibras vegetais. Development and Characterization of Polymeric Composites Based on Poly (Lactic Acid) and Natural FibersAbstract: This work evaluates the behavior of composites containing a biopolymer derived from sustainable agriculture industries. The biopolymer selected, poly(lactic acid) -PLA -, in combination with a thermoplastic polymer (polyurethane) -TPU -was mixed with natural fibers, wood and coconut. In a first step, formulations containing 10, 20 and 30% by weight of fiber in relation to the blend of PLA-TPU (in the ratio 70/30 wt%) were prepared. In the second step, the same set of formulations was maintained but with addition of 5 wt% of the coupling agent maleic anhydride. These composites were characterized by means of physical-mechanical, thermal and microscopic techniques. The results indicated a low interfacial bonding between the polymeric blend and the vegetal fibers. It is important to emphasize the poor performance of the coupling agent, because the formulations containing maleic anhydride did not show any improvement in their properties in comparison to the standard material. Therefore, the biocomposites studied in this paper can be used when high-performance materials are not required, as in home decoration articles, making it feasible to use vegetal fibers in order to reduce the cost of the final composite. Keywords: Biopolymer, poly(lactic acid), polymeric composites, vegetal fibers. IntroduçãoMuito tem sido discutido sobre as principais políticas de gestão de resíduos de materiais utilizados na indústria em geral, porém, a maior reflexão ...

This study evaluates the thermal, morphological and mechanical behavior of polypropylene (PP) composite with different natural fibers. The fibers used were wood, sugarcane, bamboo, babassu, coconut and kenaf with and without coupling agent. The thermal, morphological and mechanical properties were evaluated, and a composite PP+GFPP (glass fiber) was used as reference. The interaction at the interface fiber-polymer matrix was studied by scanning electron microscopy (SEM) at the fractured surface of the composites, as expected the presence of maleic anhydride (MA) as coupling agent increasedthe interaction at the interface. The influence of natural fiber in the degree of crystallinity of the composites was evaluated by DSC analysis. The samples of PP+GFPP and PP+(PP-MA)+WF (wood flour) showed better temperature stability. PP+GF also presented superior flexural modulus. The thermal dynamic mechanical behavior was evaluated by DMA, a decrease in storage modulus with increasing temperature was observed, the PP+GF and the composite containing maleic anhydride and sugarcane fiber showed higher modulus. The natural fiber biocomposites studied, consistently presented lower flexural modulus and tensile strength than the reference composite, with and without the use of coupling agent. As expected the use of natural fibers lowered the density compared to the reference material.

The use of recycled raw materials and renewable sources are necessary for economical, social, environmental and technological development. In this context, this work aims to study the influence of two lignin types, one derived from pine (Lig I) and the other one from eucalyptus, (Lig II) on polymer composites properties of recycled low density polyethylene (r-LDPE-Al) and Pinus Elliotti wood flour (WF), in the proportion 70% and 30% matrix/reinforcement in weight, respectively. The r-LDPE-Al is from Tetra Pak post-consumer packaging. The composites were processed by extrusion in a laboratory co-rotation twin-screw extruder. The composites obtained were evaluated through tests of melt flow index (MFI), tensile strength, Charpy impact strength, density and heat deflection temperature (HDT). The MFI results indicated that both lignin showed potential use as a flow agent for r-LDPE-AL/WF composites, with an increase of  41% and 13% for Lig I and Lig II, respectively, when compared with composite reference 0 (without lignin). Mechanical test results showed that the lignin origin influences the composites’ properties where Lig I, is derived from pine (the same source as wood flour) had the best performance, indicating a potential use as a coupling agent. The results were favorable for a more noble reuse for post-consumer packaging and the lignin by-product.