Effectiveness of Maleated and Acrylic Acid-Functionalized Polyolefin Coupling Agents for HDPE-Wood-Flour Composites

The performance of fiber reinforced thermoplastic composites strongly depends on solid fiber-matrix adhesion to allow stress transfer between the phases. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and the polymer. This study investigated the effects of coupling agent's functional monomer (acrylic acid vs. maleic anhydride) and base resin (polyethylene (PE) vs. polypropylene (PP)) types on the tensile and flexural properties of high-density polyethylene (HDPE)-wood-flour composites. The interfacial adhesion between wood flour and HDPE matrix was examined using environmental scanning electron microscope. The experimental results indicate that the types of functional monomer and base resin are important factors determining the effectiveness of functionalized coupling agents for HDPE-wood-flour composites. Maleic anhydride-functionalized polyolefins perform better than acrylic acid counterparts whereas PE-based maleated coupling agents are more effective than PP-based counterparts in improving the strength properties of HDPE-wood-flour composites.