Incorporation of Recycled Polypropylene and Fly Ash in Polypropylene-Based Composites for Automotive Applications

The principal aim of this study is to investigate the utilization feasibility of waste materials, i.e., recycled Polypropylene (PP), and fly ash in the formulation of auto parts which are commonly designed based on PP. The typical formulation of auto parts consists of PP, elastomer, filler, and compatibilizer. Various recycled PP/virgin PP ratios were considered as the matrix of the composites. It is found that the increasing concentration of recycled PP in the composite leads to a reduction in mechanical properties, particularly ductility and impact strength. However, due to a lower viscosity at the presence of recycled PP, better dispersion of filler particles, observed by SEM analysis, leading to the improvement of tensile strength. Besides, the employment of recycled material lowers the percentage of crystallinity and melting temperature. It is deduced that the deployment of 20/80 to 40/60 ratios of recycled PP/virgin PP in the composites reasonably meets the requirements for auto parts with advantages in the environmental and economic aspects. Compared to the composites filled with talc, the ductility of fly ash-filled composites is higher. The simultaneous utilization of talc and fly ash as a hybrid system brings about higher ductility, but lowers impact strength compared to talc-filled samples. Using recycled PP mixed with fly ash provides advantages in cost reduction and sustainable and environment-friendly production.