Abstract:

In the present work, hydrothermal-microwave treatment was used for elm dimension-timber softed treatment. Ratio of longitudinal compressing, single and muti-dimensional minimal curvature radius were used to evaluate the softening result. XRD and FTIR were used for the characterization of surface composition and crystallinity. The results show that hydrothermal-microwave treatment can soften elm dimension-timber significantly, the content of extractive and hemicellulose also decreased significantly. The content of lignin increased slightly（1.73%～0.47%）. In addition, the number of hydroxyl groups on wood surface increased significantly. For the non-crystalline region, microsoft fiber tended to arrange orderly and increase the degree of crystallinity. In the crystal region, the hydroxyl of the sur-microsoft fiber was exposed and the hydrogen bonding enhanced and the width of crystal region increased. When treated under the optimum condition of scheme B, the ratio of longitudinal compressing reached maximum and the single and muti-dimensional radius reached minimum. The main reason of the best softening performance of sample B was the high degree of crytallinity and appropriate number of hydroxyl.

Key words: elm, hydrothermal-microwave treatment, softening wood properties, longitudinal compressing