Physical and mechanical properties of fast-growing eucalypt wood under high temperature heat treatment

GAO Wei1,2, LUO Jian-ju1,2 *, LI Qu-en1,3 (1 Forestry College, Guangxi University, Nanning 530005, China; 2 Guangxi Wood Products Quality Supervision and Test Station, Nanning 530004, China; 3 Sichuan Gulin Langjiu Liquor Sales Co. Ltd., Chengdu 610020, China)

fast-growing eucalypt wood; high temperature heat treatment; physical properties; mechanical properties

[Objective]This research studied the changes in physical properties and mechanical properties of fast-growing eucalyptus wood that underwent high temperature heat treatment to provide parameters for industrial production.[Method]Under water vapor protection, wood samples were heat treated at different temperature levels (160, 180, 200, 220, and 230℃) under three different time durations (1, 2, and 3 h), then the physical and mechanical properties were determined according to GB/T 1927-GB/T 1943 national standards. [Result]As the temperature of heat treatment increased, the moisture content increased considerably while the dry shrinkage rate, water absorption, and wet expansion rate gradually decreased. The wood density decreased as the temperature increased and treatment time prolonged. Effects of the processing time on the parallel-to-grain compression strength and the impact toughness and hardness were significant. Heat treatment for 1 h was optimal out of all heat treatment conditions. Under the same temperature conditions, the flexural strength was the highest after 1 h of treatment, medium after 3 h of treatment, and lowest after 2 h of treatment. As the heat treatment temperature increased, the elastic modulus first increased then decreased. [Conclusion]High temperature heat treatment had great effects on the physical properties of eucalyptus wood, in which the dry shrinkage, absorbent condition, and expansion condition obviously decreased and the dimensional stability increased. As the treatment temperature increased and the heat treatment time continued, the mechanical properties of fast-growing eucalyptus wood exhibited an overall declining trend.