处理温度对高温热改性橡胶木物理力学性能的影响

Effects of Treatment Temperature on the Physical and Mechanical Rroperties of Thermal Modified Rubber Wood

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 heat-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.