Eco-Friendly Polypropylene Composite Reinforced with Natural Fillers: Mechanical Properties and Wear Resistance

Abstract

Natural composite materials are gaining interest due to their low cost, recyclability, and availability. This study examines hemp-polypropylene (HPP) composites, where polypropylene (PP) is reinforced with 30 wt.% short hemp fibers (HF). The composites were produced via melt compounding using a twin-screw extruder, followed by injection molding. To improve adhesion between hydrophilic hemp fibers and the non-polar PP matrix, polypropylene-graft-maleic anhydride (PP-g-MA) was used as a coupling agent. Structural and mechanical properties were assessed using SEM, FTIR, tensile, and scratch tests. Results revealed a significant improvement in fiber-matrix adhesion with the use of PP-g-MA, demonstrating enhanced interfacial bonding. The hemp fibers were uniformly dispersed within the PP matrix, resulting in a dense and homogeneous composite structure. Mechanically, the addition of 30 wt.% HF markedly increased the stiffness and tensile properties of the composites. The Young’s modulus and tensile strength of the HPP composites reached 3804 MPa and 28.07 MPa, respectively, compared to 1523 MPa and 22.98 MPa for neat PP. Scratch testing further supported these findings, showing a notable reduction in penetration depth upon the inclusion of hemp fibers. This study highlights the potential of hemp-reinforced polypropylene composites as a sustainable alternative in applications requiring enhanced mechanical performance.