Compósitos poliéster/tecidos tramados vegetal-vidro: caracterização mecânica e simulação da sorção de água.

Abstract

This work deals with the mechanical performance and the water sorption characteristics of compression molded unsaturated polyester composites reinforced with an all jute fabric and an especially manufactured hybrid jute-glass fabric having jute strings on the warp and glass fiber roving on the weft. The mechanical performance of the composites was investigated as a function of total and relative fiber content, test direction and fiber identity and content along the test direction. A tri-dimensional transient mathematical modelling was used to predict mass transfer during the water sorption by these composites. The data show composite tensile, flexural and impact properties to increase with fiber content. Best overall properties were obtained for the composites tested along the glass fiber direction where tensile strength, tensile and flexural modulus and impact strength up to 5.9; 3.6; 3.7 and 15.8 times higher than those of the neat matrix were obtained for composites with 58% and 32% (glass) w/w total and relative fiber contents. Fabric hybridization with glass fibers not only promoted an increase in composite mechanical performance but also led to a decrease on water uptake by the composites. The mathematical formulation was numerically solved by a finite volume method and a completely implicit interpolation scheme. Results on the evolution of the average humidity within the material during water uptake are shown, analyzed and compared with the experimental data. A satisfactory fit was obtained and the water diffusion coefficient, as well as the humidity distribution within the material, was estimated from this fit by employing a minimum quadratic error technique.