Enhanced Mechanical and Morphological Properties of Surface-Modified Industrial Hemp Preform as Reinforcements in 2D Vinyl Ester Composites for Automotive Interiors

This study investigated the influence of surface modification on the mechanical and morphological properties of industrial hemp preforms reinforced in 2D vinyl ester composites produced through the Vacuum-Assisted Resin Transfer Molding (VARTM) technique. Industrial hemp preforms were grafted with methyl methacrylate (MMA) monomer to enhance fibre matrix interfacial bonding. The grafting efficiency (44.2%) and grafting percentage (21.5%) were determined, and the resultant grafted and ungrafted composites were evaluated for tensile, flexural, impact, hardness, and abrasion resistance properties according to ASTM standards. The results revealed significant mechanical enhancement in grafted composites. The tensile and flexural strengths increased from 44.57 MPa and 51.34 MPa (ungrafted) to 69.42 MPa and 85.34 MPa (grafted), respectively, representing approximately 55% and 66% improvements. Impact strength rose from 3.83 kJ/m² to 7.05 kJ/m², while Shore D hardness increased from 80.83 to 90.5, indicating better surface rigidity and interfacial cohesion. SEM micrographs confirmed reduced voids, fibre pull-out, and improved matrix wetting in grafted composites, demonstrating the effectiveness of MMA grafting in improving adhesion and load transfer efficiency. The study concludes that surface modified ihemp preforms exhibit superior performance compared to ungrafted ihemp preform making them promising materials for sustainable, lightweight, and eco-friendly interior components in the automotive.