Combined effects of boron and compatibilizer on dimensional stability and mechanical properties of wood/HDPE composites

Thickness swelling, water absorption, and mechanical properties of the wood flour-high density polyethylene composites incorporated with different contents (4, 8, or 12 wt.%) of boron compounds (borax/boric acid and zinc borate) and compatibilizer (2, 4, or 6 wt.% maleic anhydride-grafted polyethylene (MAPE)) were investigated. The dimensional stability and mechanical properties of the uncoupled samples, except for the modulus of elasticity, were negatively affected by increasing the boron content while these properties were positively affected by increasing the compatibilizer content. The samples containing the zinc borate showed better dimensional stability and the flexural, tensile, and impact properties compared with the samples containing the borax/boric acid. The dimensional stability of the samples increased when the contents of the compatibilizer MAPE and boron compounds increased to 4% and 8 wt.%, respectively. However, a further increment in the content of the boron compounds (12 wt.%) negatively affected the dimensional stability and mechanical properties of the coupled samples (6 wt.% MAPE), except for the modulus of elasticity.