Effects of hybridization and interface modification on mechanical properties of wood flour/polymer composites reinforced by glass fibers

Hybrid composites based on natural fibers were reinforced by glass fibers (GFs), the mechanical properties and microstructural morphology were investigated. Three types of GFs (3 mm, 4.5 mm, and 6 mm in length) and four GF concentrations (5%, 10%, 15%, and 20 wt%) were used to clarify their effects on mechanical properties, respectively. γ‐aminopropyltriethoxysilane (APTS) and maleic anhydride grafted polyethylene (MAPE) were used as the coupling agents to enhance the compatibility between fibers and high density polyethylene (HDPE). The results showed: (1) when 30% wood flour (WF) was incorporated, 4.5 mm‐long GF with 15% addition was the optimum formula used to improve most mechanical properties. The GF with 6 mm‐length or 20% addition could cause aggregation to destroy the continuity of matrix, leading to decreased mechanical properties. (2) Mechanical values increased within the concentration of APTS from 0% to 1.5% and decreased at 2% due to the self‐condensation behaviors of hydrolyzed silane. Extra –OH groups could cause incompatibility in the mixed system. MAPE could constantly improve the mechanical properties with the increase in MAPE concentration. (3) WF had the positive effect on tensile strength and flexural properties, and GF showed the advantageous contribution to impact strength. A mechanism concerning the reinforcing mechanism of the hybrid composites was proposed based on research results. POLYM. COMPOS., 40:3601–3610, 2019. © 2019 Society of Plastics Engineers