Effect of cupuaçu residue incorporation as a vegetal filler on the properties of polystyrene

Cupuaçu husk was used as vegetal filler in polystyrene, aiming to investigate its influence on the properties of the polymer. The chemical characterization of the residue was carried out using FTIR and FRX. The thermal behavior was studied by TG/DSC. Surface morphology was observed by SEM. The particle size distribution was evaluated by laser scattering. Four types of test samples were fabricated: a sample containing only pure polystyrene and other ones filled with 1, 2, and 3% of residue. Furthermore, samples were subjected to thermal aging in an oven. 30-day oven-aged and unaged samples were characterized mechanically (tensile test), thermally (TG/DSC) and chemically (FTIR). In addition, fracture region was evaluated by SEM. The filler incorporation affected positively the mechanical behavior of the polymer. The degradation temperatures presented some increase along with the incorporation of the filler. Also, DSC curves suggested that the filler incorporation might have inhibited the formation of low molecular weight molecules detected in curve of pure-PS sample. It suggests that the residue can be a viable option as a thermal stabilizer. These results imply that the incorporation of the cupuaçu residue may have some positive influence in the performance of mechanical and thermal properties of the polystyrene.