处理温度对高温热改性橡胶木物理力学性能的影响

摘要

以过热蒸汽为介质常压高温热改性人工林橡胶树木材,处理温度为170、185、200和215℃,处理时间均为3 h.分析了处理温度对热改性橡胶木物理力学性能的影响,结果表明:提高热处理温度,橡胶木的平衡含水率显著降低,降幅为34.33%～62.97%;干缩率显著降低,降幅为3.1%～51.75%(弦向)和2.72%～48.57%(径向);湿胀率显著降低,降幅为37.80%～69.85%(弦向)和28.04%～68.57%(径向);吸水率轻微下降,但不显著;热改性后,橡胶木的尺寸稳定性明显提高.气干密度、全干密度仅在215℃处理时明显下降,其余处理温度变化不显著:弦面硬度先略微增加,后急剧降低,整体呈下降态势;弦、径向局部横纹抗压强度先升高后下降,整体呈增加态势;抗弯强度显著降低,降幅为9.26%～37.52%;抗弯弹性模量有增加,但不显著.%The effects of temperature on physical and mechanical properties of rubber wood beat-treated in superheated steam were investigated in this paper. Specimens which cut from planted forest were thermally modified at 170, 185, 200℃ and 215 ℃ for 3 hours. The results indicated that the specimens' equilibrium moisture content of wood decreased significantly from 34.33％ to 62.97％ with the increasing temperature. The changes of oven-dry density and air-dry density were not significant except for 215 ℃. Significant decreases of 3.1％～51.75％(tangential) and 2.72％～48.57％(radial) were observed in Shrinkage properties, and the decrease in swelling properties ranged from 37.80％～69.85％ (tangential) and 28.04％ ～68.57％ (radial), whereas the water adsorption diminished slightly. These changes were beneficial to the increase of dimensional stability. Moreover, a significant loss of 9.26％ to 37.52％ happened in modulus of rupture, but increase tendency of modulus of elasticity were also observed except for one trail which specimens were thermally modified at 185 ℃. Meanwhile,the hardness presented the tendency of decrease, but the compressive strength showed increase tendency in all.