Properties and durability of wood impregnated with high melting point polyethylene wax for outdoor use

Abstract

In order to develop a new wood product suitable for outdoor applications, a high melting point polyethylene wax was used for high-pressure impregnation treatment of wood. Properties of impregnated wood were studied. Wax in molten state was stable with low viscosity, good fluidity, and easily penetrate into the wood under high pressure. Full-cell process included vacuum (-0.06 MPa for 30 min), high-pressure impregnation (0.75 MPa for 3 h) and pressure release (30 min). Wax contents of treated lodgepole pine (Pinus contorta Douglas ex Loudon.) and eucalyptus (Eucalyptus saligna) were 0.205 g/cm3 and 0.321 g/cm3, respectively. Cell gaps and cell cavities of wood were filled with polyethylene wax. Nanoindentation tests showed that longitudinal mechanical properties of wood cell walls were weakened after impregnation. After a 3 h high-pressure impregnation, hardness of lodgepole pine wood cell walls was reduced by 35.1%, and the modulus of elasticity was reduced by 4.9%. Treated wood had a much lower water absorption and swelling rate than untreated wood, its weathering resistance as well as insect resistance were better.