Effect of partial replacement of CaCO3 with palm kernel shell particles on the mechanical properties of PKS/CaCO3/HDPE hybrid composites

The use of biofillers as reinforcement in polymer matrix composite material has increased due to numerous advantages such as high strength, eco-friendly, and high strength-to-weight ratio. In this work, the effect of different sized palm kernel shells (PKS) and calcium carbonate (CaCO3) as filler materials on the mechanical, physical, and thermal properties in High density polyethylene (HDPE) was studied. The fillers were melt-blended with HDPE using Noztek single-screw extruder, and the sample was prepared using hot pressing and injection molding. The effects of PKS on the microstructure, tensile strength, impact strength, hardness, and thermal properties were analyzed. Significant improvements were observed in the ternary composites. The results showed that Young's modulus was decreased by 9.5 % and 4.9 % for the 125 μm and 500 μm hybrid, respectively. The addition of PKS showed significant improvement in tensile and hardness properties. An increase of approximately 0.9 % and a decrease of 7.7 % were observed in the tensile strength for the 125 μm and 500 μm hybrid, respectively. A decrease of 82.23 % and 83.37 % were observed for the impact strength of the 125 μm and 500 μm hybrid, respectively. The hybrid composite showed a more promising result regarding the hardness, with a 44.5 % and 44.7 % increase for the 125 μm and 500 μm hybrid, respectively.

SEM analysis of the composite surfaces revealed relatively good interfacial interactions between the palm kernel shell particles and the HDPE/CaCO₃ matrix.