Properties of recycled polypropylene/quarry dust composites

Rapid urbanization is placing unsustainable pressure on conventional construction materials and recycling waste products into useful materials presents an opportunity to develop viable substitutes. In this study, the viability of recycling waste polypropylene with quarry dust was investigated. Recycled PP/quarry dust composites with four particle sizes and varying filler loading were melt-blended in a single-screw extruder and then transfer moulded. No new functional groups were detected in the FTIR spectra. The TGA results showed that quarry dust particles enhanced the thermal stability of recycled PP. The SEM analyses showed that the compatibility between the two phases was relatively poor. Tensile strength and impact strength generally deteriorated with increasing filler content by up to 37.1 and 24.3 at 13.91 vol%, respectively. However, significant improvements in Young's modulus (37%) and compressive strength (16%) were observed with both filler content and decreasing particle size. Elongation at break dropped drastically with increasing filler content to nearly 0% at 13.91 vol%. The water absorption of the composites was very low and deemed unlikely to affect their performance. This study shows that incorporating quarry in PP is beneficial and the resulting material can be used to make low-cost composite products that may be used in construction.