Cork-wood hybrid filler system for polypropylene and poly(lactic acid) based injection molded composites. Structure evaluation and mechanical performance

Presented work discusses comparative studies of the use of a hybrid filler system on the properties of polypropylene and poly(lactic acid) composites. Wood flour have been added to improve the initially poor material performance of cork based composites. The hybrid cork/wood filler system used during this study was introduced to polymer system by two step extrusion/injection molding process in the amount of 10, 20 and 30 wt %. Samples were subjected to detailed thermo-mechanical and structural analysis. The investigated hybridization method was successfully implemented, leading to the enhancement of mechanical characteristics comparing to pure cork composites. Density analysis in combination with structural observations, confirmed significant changes in the morphology of cork, including the loss of the cellular structure, due to high shearing of the injection molding process. The favorable results of water absorbency tests indicate the potential use of cork filler to improve the dimensional stability of composites.