Increased Dimensional Stability of Eucalyptus grandis × Eucalyptus urophylla ‘GLGU9’ Wood through Palm Oil Thermal Treatment

Eucalyptus grandis × Eucalyptus urophylla ‘GLGU9’ is one of the most commonly planted tree species in South China. It is a new variety created by Guangxi Zhuang Autonomous Region Forestry Research Institute. As a fast-growing species, the poor dimensional stability is one of its main drawbacks, which restricts its applications. Thermal treatment is one of the effective methods to improve the dimensional stability of wood. GLGU9 wood was treated using thermal modification with palm oil. The oil was used as a heating medium and a shielding material at temperatures of 150, 170, 190, 200, and 210 °C, at various treatment durations of 1.5, 3, 4.5 and 6 h. To investigate the effect of palm oil thermal treatment on dimensional stability, the anti-shrink efficiency (ASE1) and anti-swelling efficiency (ASE2) were examined. The results indicated that the ASE1 and ASE2 were increased by 62.8% and 56.6% at 210 °C for 6 h treatment, respectively.