过热蒸汽温度对马尾松干燥速率和力学性能的影响(英文)  

Effects of the superheated steam temperature on the drying rate and mechanical properties of masson pine wood

作　　者：程曦依 李贤军[1] 贺霞[1] 李芸[1] 熊幸阳 谢杰[1] 全鹏[1] 

机构地区：[1]中南林业科技大学材料科学与工程学院,长沙410004

出　　处：《林业工程学报》2016年第6期51-57,共7页Journal of Forestry Engineering

基　　金：国家林业局“948”项目(2014-4-50);“十二五”国家科技支撑计划课题(2015BAD14B01)

摘　　要：以常压过热蒸汽为干燥介质,对马尾松板材进行干燥处理。研究了过热蒸汽温度对马尾松木材干燥速率、力学性能、尺寸稳定性和微观结构的影响规律。结果表明:过热蒸汽干燥可以有效提高马尾松板材的干燥速率,增大板材的弹性模量及静曲强度,一定程度上影响了板材的尺寸稳定性。随着过热蒸汽由120℃升至130,140和150℃,干燥速率显著从014%/min增大至018,019,020%/min,其显著水平为99%。除150℃处理试件表现出大量的內裂和最低的力学强度外,当过热蒸汽温度分别为120,130和140℃时,静曲强度分别增加了2990,3259和3787 MPa,弹性模量分别增加了2 275,901和780 MPa。与常规干燥材相较,过热蒸汽处理材表现出更强的吸水能力,在120℃时获得的最大弦向、径向和体积膨胀率分别显著增加了2089%,1918%和4026%,而150℃处理材各向尺寸分别降低了2051%,1258%和1610%。从微观结构观察发现,过热蒸汽处理试件出现了大量破裂的纹孔膜及树脂重新分布后的树脂道间隙。In this study, superheated steam at atmospheric pressure was used for the drying of masson pine （ Pinus mas- soniarta Lamb. ） lumber, and the effects of the superheated steam temperature on the drying rate, mechanical properties, dimensional stability and microstructure of the dried wood was investigated. The results showed that the superheated steam drying improved the drying rate, increased the modulus of elasticity （MOE） and modulus of rupture （MOR）, and decreased the dimensional stability. With an increase in superheated steam temperature from 120 ℃ to 130, 140 and 150 ℃, the drying rate were increased from 0. 14%/min to 0. 18, 0. 19 and 0.20%/min （ct〈0.01） , respectively. The MOR significantly increased by 29. 90, 32. 59 and 37. 87 MPa, and MOE increased by 2 275, 901 and 780 MPa at steam temperature of 120, 130 and 140 ℃, respectively. However, when the drying temperature was 150 ℃, the lowest mechanical strength was obtained and also numerous internal checks were observed. Compared with the conventionally dried wood, the higher water absorption was obtained in superheated steam-dried specimens, the reduced dimensional stability was showed as increased tangential swelling （TS）, radial swelling（RS） and volume swelling（VS） for 20.89%, 19. 18% and 40. 26%, while the improved dimensional stability was obtained as decreased TS, RS and VS for 20. 51%, 12. 58% and 16. 10%, respectively. Due to the high temperature of the superheated steam, the broken pits and unfilled resin canals improved the permeability of the wood, thereby enhancing the drying rate and the water absorption capability.

关 键 词：过热蒸汽干燥 马尾松 干燥速率 力学强度 尺寸稳定性 微观构造 

分 类 号：S781[农业科学—木材科学与技术]