不同状态下的胡杨木材水分特性对比研究

A Comparative Study on the Moisture Characteristics of Populus euphratica under Different Conditions

木材的水分特性对木材的干燥工艺和木材使用具有重要意义,对于胡杨这种珍贵木材,水分是它3 000a不倒的主要影响因素,对比研究胡杨木3个不同状态,即活立木、伐倒木、枯倒木的水分特性,对胡杨木的存放、应用具有很重要的意义。选取内蒙古额济纳旗胡杨林保护区的胡杨木作为对象,分别研究初含水率、尺寸稳定性、吸水性、平衡含水率等水分特性,同时利用核磁共振技术探究气干和室干2种状态下的木材水分的驰豫特性(T2值)。结果表明,初含水率:活立木>伐倒木>枯倒木,线向干缩率:弦向>径向>纵向,体积干缩率:活立木>伐倒木>枯倒木,枯倒木的尺寸稳定性最强。在T2值反演后观察到气干状态下活立木含有2种结合水,而伐倒木和枯倒木只有1种结合水,活立木中水分与木材的结合能力较强,而伐倒木和枯倒木相对较弱。活立木、伐倒木、枯倒木水容量分别为:128%、156%、153.9%。平衡含水率:活立木1.94%,伐倒木1.80%,枯倒木1.33%。

It is of importance to study the characteristics of wood moisture for wood drying and use. Water is the main factor affecting the decay of Populus euphratica wood. In this paper,water conditions of three P. euphratica trunks were examined,to study the storage conditions of the wood,i, e. living tree （LT） ,felled tree （FT） ,and naturally felled and decayed trees （NFT） occurring in Ejina Banner of Inner Mongolia. The water characteristics included initial water content, dimensional stability, water absorption, and equilibrium moisture content,respectively. The relaxation characteristics （T2 value） of wood moisture of air dried and kiln dried wood were investigated by NMR. The results showed that the initial water content was in the or- der of LT ~ FT~ NFT. Linear shrinkage ratio was tangential 〉 radial 〉 longitudinal,volume shrinkage ratio was LT〉 FT〉 NFT,the dimensional stability of NFT was the strongest. After the T2 value was re- trieved,it was observed that the wood of LT contained two kinds of combined water in the air dried state, and FT and NFT just contained one kind of combined water. The water in LT had a strong ability to com- bine with the wood, and it was weak in FT and NFT. The water capacities of LT, FT, and NFT were 128% ,156% and 153. 9%, respectively, and the equilibrium moisture contents were 1.94%, 1. 80%, and 1.33%, respectively.