The Comparison of Properties of (Rubber Tree Seed Shell Flour)-Filled Polypropylene and High-Density Polyethylene Composites

The effect of varied rubber tree seed shell flour (RSSF) filler loadings on processing torque, mechanical, thermal, water absorption, and morphological properties of polypropylene (PP) and high-density polyethylene (HDPE) composites has been studied. The addition of RSSF in the composites increased the stabilization torque in both PP- and HDPE-based composites. Tensile strength, elongation at break, flexural strength, and impact strength show significant reduction when higher loading of RSSF was incorporated, while tensile modulus and flexural modulus were improved. The phenomenon was noted for both matrices, PP and HDPE, but HDPE-based composites showed clear effects on the reduction of the mechanical properties compared with RSSF-filled PP. Scanning electron microscopy of tensile fracture specimens revealed the degree of dispersion of RSSF filler in the matrices. At higher filler loadings, agglomerations and poor dispersion of RSSF particles were spotted, which induce the debonding mechanism of the system. Thermogravimetric analysis thermograms showed that both PP- and HDPE-based composite systems with higher RSSF content have higher thermal stability, initial degradation temperature, degradation temperature, and total weight loss. Water absorption ability of the composites increases as the filler loading increases for both matrices. (C) 2014 Society of Plastics Engineers