Properties of hardboards made from acetylated aspen and southern pine

The effects of fiber acetylation, resin content, and wax content on mechanical and physical properties of dry-process hardboard made from aspen and southern pine were investigated. Test results indicate that the modulus of rupture (MOR) and modulus of elasticity (MOE) of the hardboard specimens were decreased due to the fiber acetylation. Tensile stress parallel to face and internal bond (IB) were generally higher for untreated boards than for acetylated boards. Water ab- sorption (WA) and thickness swelling (TH.S) were both reduced markedly by acetylation. In general, increasing resin content from 3% to 7% brought increases in MOR, MOE, tensile stress, and IB and improved WA and TH.S. Addition of the 0.5% wax content usually caused reductions in these mechanical properties, but improved WA and TH.S in some cases. Linear expansion (LE) in the dimensional stability test (from 30% to 90% RH) was significantly reduced by acetylation and influenced by wood species. Neither resin nor wax contents significantly affected the LE value of hardboard specimens in this study