Compósitos de polipropileno reciclado reforçados com torta de mamona in natura e tratada quimicamente

Abstract

The production of polymeric composite materials reinforced by natural fibers has become an interesting alternative due to the low cost of fibers, their biodegradability, low specific mass and because they are found in abundance in nature. Thus, it has been sought to combine the most different types of polymers with fibers from agricultural residues that produce composites with properties similar to or superior to pure polymers. A widely used method in the manufacture of these composites is the chemical treatment of natural fibers to improve the interfacial adhesion between the fiber and matrix. Thus, this study aimed to apply different contents of castor cake particles in natura and treated with maleic anhydride and sodium hydroxide as reinforcement in recycled polypropylene (PP) composites and to evaluate how changes in physical, mechanical and microstructural properties before. The compositions for partial replacement of recycled PP with castor cake were 0%, 10%, 20% and 30% (w / w), which went through the extrusion and pressing process to manufacture the specimens. After preparation, the specimens were placed in an air conditioning room at 20 ± 2 ° C and a relative humidity of 65 ± 3% until the physical-mechanical tests of water absorption, density, traction, flexion and impact were carried out. A morphological analysis was also performed by scanning electron microscopy (SEM) of the composites and particles of the castor cake in natura and superficially treated. The results sought that there was no limited variation in density for the studied replacement contents. The treatments with maleic anhydride and sodium hydroxide increased the surface roughness of the particles and composites, which improves the adhesion between the reinforcement and the matrix. However, maleic anhydride caused the defibrillation of castor cake particles. The compounds with particles treated with sodium hydroxide differentiated the best behavior of tensile strength. The increase in the particle content of fresh castor cake increases the impact resistance in compacts, which is up to 75% when compared to the impact resistance of pure recycled PP. There were no relevant changes for water absorption and elastic modulus (MOE) in the bending of the composites. These results show a potential use of this composite.