Effects Of Pre-Heat And Pre-Freeze Treatment Prior To Drying Upon Wood Physical Properties Of Eucalyptus Urophylla × Eucalyptus Grandis Wood

Eucalyptus is one of the most important fast-growing plantation tree species planted in China. However, many species of Eucalyptus tend to crack, collapse, and exhibit discoloration because of the large growth stress during drying. Choosing different moisture content wood as experimental material, investigating the effect of preheat and pre-freezing treatment of eucalypts on the wood properties. Including the properties of shrinkage and mechanical properties. Using the CIE (L*a*b*) system for quantitative characterization of wood color; Using scanning electron microscope (SEM) to look at the wood microscopic structuremicrostructure, and research the change of wood structure by IR and UV spectrum. The results prove that:(1) The tangential shrinkage and the difference drying shrinkage of Eucalypt green wood(MC=100%) decreased after preheat treatment at 100 ℃, that improve the dimensional stability of wood.(2) 100 ℃ steaming treatment has little effect on the color of Eucalypt green wood(MC=100%). 120 ℃ superheated steaming treatment for 32 hours lead the color of green wood(MC=100%) changed. The color of treated wood was similar to the color of Dipterocarpus sp wood.(3) 120 ℃ superheated steaming treatment for 12 hours lead the color of low moisture content Eucalypt timber(MC=7.9%) changed. The color of wood was similar to the color of Cinnamomum cansonor wood.(4) The shrinkage and mechanical properties of Eucalypt green wood(MC=40%) decreased after pre-freezing treatment, pre-freezing at-20 ℃ is better than that at-40 ℃ for improving the shrinkage and color of E. urophylla x E. grandis wood.