Characterization of thermoplastic starch composites reinforced with sugarcane bagasse fibers
Brazil is a country that produces a lot of lignocellulosic residue, and of different types. In view of this, many researches to define an environmentally acceptable fate have been made, and one of the destinations for such waste is to replace synthetic fibers as the dispersed phase in polymeric composites, thus forming a biodegradable material. In this project, residues from the sugarcane bagasse were used, with fibers before and after alkali treatment and in different sizes as a dispersed phase of a thermoplastic starch composite in order to investigate the influence of fiber size and chemical treatment on the properties of the same. The composites were produced by extrusion and the films formed by molding. To characterize the composites obtained and the starting materials, chemical, mechanical, thermal and morphological analyzes were performed.
The characterization of the fibers in different size ranges showed that the size does not interfere in the chemical composition and the thermal properties of the same. However, the crystallinity index and the aspect ratio were altered, with the larger fibers having larger values. Absorption and moisture content also changed, with smaller fibers having the highest values. The characterization of the treatment conditions indicated that the time did not significantly influence the result, except for the XRD that showed a tendency in the increase in the crystallinity index of the fiber with up to 1h of treatment. Determination of the chemical composition of the starting fiber and fiber after 1 h of treatment showed the efficiency of the treatment with a significant reduction in the hemicellulose and lignin content of the fiber. The composites with different sizes presented mechanical properties similar to TPS. Optical microscopy showed that the fibers were not well dispersed in the matrix, impairing the performance of the material and the use of new pressing conditions of the films in order to obtain greater homogeneity in the dispersion of the fibers.