Biocomposites from high density biopolyethylene and curaua fibers / Biocompósitos a partir de biopolietileno de alta densidade reforçado por fibras de curauá

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

In this work, curaua fibers were used in the reinforcement of a high-density (HDPE) thermoplastic matrix. The polyethylene used in this study was obtained by polymerization of ethene produced from sugarcane ethanol. This polymer, also called high-density biopolyethylene (HDBPE), was prepared from a natural source material. The aim of the present study was to contribute to the development of materials that, among other properties, release less CO2 into the atmosphere as compared to other materials. The curaua fiber surface was modified by treatment with ionized air, seeking improved fiber impregnation by the matrix, which would possibly enhance the fiber/matrix interface adhesion. The properties of the composites reinforced with this fiber (randomly distributed, 1-cm long, different amounts, thermopressed materials) were compared with those reinforced with non-modified fibers. Additionally, liquid hydroxylated polybutadiene (LHPB) was added to the composite formulation, aiming at improving resistance to crack spreading during impact. The fibers and their composites were characterized by several techniques, such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetry (TG). The composites were also characterized by dynamic mechanical thermal analysis (DMTA), mechanical properties (flexural and impact strength), and water absorption. The presence of curaua fibers reduced some of the properties of the HDBPE, such as flexural and impact strength. DMTA showed that the presence of the fibers results in a more rigid material. The addition of LHPB to the formulation was efficient, leading to greater impact strength for the HDBPE/LHPB/fiber composite, as compared to the HDBPE/fiber composite. The addition of over 15% LHPB to the composite resulted in a poor mixture of the component, as evidenced by the flexural strength. The mechanical properties of the materials were not greatly influenced by their reinforcement with fibers treated with ionized air as a whole, showing that the process parameters can be further investigated to minimize the degradation of the materials. The use of a rubber with a higher average molar mass that the one currently used may have a greater effect on the impact strength. Longer fibers in equal mass proportions to those used in the present study can be tested, since shorter fibers mean a larger number of ends, which may act as stress concentrators and worsen some mechanical properties of the composite.

ASSUNTO(S)

biocompósitos curaua fibers biopolietileno biopolyethylene biocomposites fibra de curauá

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