Improving durability and mechanical resistance of wood/plastic composites through boric acid treatment

In this study, the effects of boric acid (BA) treatment on the mechanical properties and decay resistance of poplar wood flour/polypropylene composites (WPCs) were investigated. Three composite groups were prepared: untreated WPC (UT-WPC), BA-treated WPC with in-process powder addition (BA-T-WPC), and BA-pretreated WPC using aqueous BA solution (BA-PT-WPC). Mechanical properties including flexural strength and modulus, tensile strength and modulus, hardness, and impact strength were evaluated before and after exposure to fungal decay (Trametes versicolor). The results showed that boric acid treatment improved several mechanical properties of undecayed WPC. Specifically, BA-T-WPC exhibited the highest flexural strength (50.77 MPa) and modulus (3473 MPa), while BA-PT-WPC demonstrated superior tensile modulus (4563 MPa) and impact strength (49.40 J/m). Decay exposure decreased all mechanical properties across all groups, although BA-treated samples retained slightly higher performance compared to the untreated control. These findings suggest that boric acid can effectively enhance the mechanical behavior and decay resistance of WPCs through both direct and pretreatment methods.