Obtenção e caracterização de compósitos preparados com poliestireno expandido reciclado e pó de madeira

Abstract

The present work aims to analyze the mechanical, thermal, dynamicalmechanical thermal properties and morphology of composites based on recycled polystyrene and wood flour. Composites with different types and levels of coupling agent and also with different levels of wood flour were developed in a co-rotating twin-screw extruder and injection molded. The results show that the coupling agent with higher amount of maleic anhydride, lower weight average molecular weight and used in to 2% by weight produced composites with better mechanical properties. The improvement in interfacial adhesion was also observed by dynamical-mechanical thermal analysis. An increase in the storage modulus, decrease in peak height and also lower value of adhesion factor, was observed due to the improved on interfacial adhesion. For the composites developed with different levels of wood flour density obtained was similar to theoretical density indicating that in accordance with the rule of mixtures. The use of coupling agent reduced the concentration of voids in the composites. The flexural modulus increases with the amount of wood flour and also approaches the behavior predicted by the rule of mixtures, however the composites without coupling agent showed reduction in flexural strength. The impact strength decreases with the addition of wood flour, but the composites with coupling agent showed better results than the composite without coupling agent for all levels of wood flour. There was an increase in the storage modulus, loss modulus and also the efficiency of filler with the addition of wood flour. There was a reduction in width and also in peak height of tan δ as the addition of wood particles, composite with coupling agent demonstrated greater reduction due to improved on interfacial adhesion. The theoretical model to predict the behavior of the storage modulus showed proximity with the experimental values for low levels of filler. Theoretical model for tan δ proved inadequate. The micrographs of composites without coupling agent indicated the presence of pulled-out traces and gaps between the wood flour and matrix, however the composites with coupling agent show the strong bonding and good wetting of the fillers by the matrix. The thermal stability of composites with coupling agent was reduced for all levels of wood flour when compared to composites without coupling agent.