The reinforcement efficacy of nano- and microscale silica for extruded wood flour/HDPE composites: the effects of dispersion patterns and interfacial modification

The reinforcement efficacy of nano-silica particles for wood/plastic composites (WPCs) has been inconsistent in previous research. Accordingly, this systematic study was conducted to verify the reinforcement feasibility using silica particles. Micro- and nano-silica particles were incorporated into high-density polyethylene (HDPE) via direct compounding (dry dispersion) or by mixing in a solution (wet dispersion), to determine the effects of dispersion and particle size on the reinforcement efficacy of the resulting wood/HDPE composites. Compared with non-filled WPCs, dry dispersion reduced the WPCs’ mechanical strength for microsilica (> 30%), but increased it for nano-silica (< 10%). Wet dispersion plus a surface treatment of silica with vinyltrimethoxysilane (VTS) improved the mechanical strengths of the WPCs by up to 30%; the creep deformation was also restricted to some extent. This study demonstrates that silica particles can reinforce WPCs to a moderate extent, if they are in the nano-diameter size range and are uniformly dispersed into the matrix of the WPC system.