Desempenho e durabilidade de fibras vegetais modificadas superficialmente e submetidas a meios ácido e alcalino.

Abstract

The use of plant fibers in composites has many viability about the use of materials from renewable sources, biodegradability and the socioeconomic advantages in the raw material vegetable production. The plant fibers are highly hygroscopic and this is a main problem in the composites production, inducing to proportion changes under the moisture influence, deposition of the matrix products and degradation. In order to find alternatives to minimize the problems in cement composites in relation to vegetable fibers, the aim of this research the application the acetylation and pyroligneous liquor impregnation treatments in order to reduce water absorption, avoiding any variation dimensional and improving its compatibility with the matrix. The acetylation and impregnation treatments were applied to the “sisal”, “caroá” and “curauá” fibers at different levels, and its efficiency was determined by reduction of hydrophilicity, maintaining the mechanical performance, and changes in chemical composition, evaluated by physical, chemical, mechanical and thermal properties. The plant fibers showed reductions in water absorption of 37% to 47% in the acetylated, and 4% to 20% in impregnated. The treatments decreased the mechanical properties of “sisal” and “curauá” fiber, and increase in strength values in “caroá” fiber. The acetylation and impregnation treatments showed interference in the chemical composition of plants fibers. For durability, the reduction in the mechanical properties was mainly related to degradation occurred during treatment. The acetylated fibers showed higher sensibility in alkaline and impregnated in acid solution.