利用时域核磁共振研究木材干燥过程水分状态变化

Water Status Change in Wood Drying Studied By Time-Domain NMR

以新疆杨幼龄材为研究对象,以水分子中的H质子为探针,利用时域核磁共振技术探究木材干燥过程中水分状态变化与迁移。通过对干燥过程中水分变化的自由感应衰减曲线(FID)和横向弛豫时间(T2)进行测定与分析,探究木材内部水分状态变化及迁移过程。结果表明:利用时域核磁共振技术测得新疆杨的理论含水率(71.90%)与实际含水率(73.74%)相差1.84%。通过T2分布描述木材干燥过程中水分的迁移,例证在木材干燥的初始阶段结合水也有缓慢减少的现象。通过不同组分水的T2弛豫时间对应的峰面积定量计算出新疆杨幼龄材中不同状态水的含量。对干燥过程中的自由水、结合水及木材总含水量的变化建立相应的数学模型。

Water states and migration in juvenile Xinjiang poplar （Populus alba var. pyramidalis） drying was studied by time-domain nuclear magnetic resonance （TD-NMR）. Water in wood drying was investigated through free induction decay curve （FID） and transverse relaxation time（T2） of proton sensor in water molecules. The results showed that the difference was 1.84% between theoretical moisture content （71.90%） and actual one （73.74%） by using TD-NMR technique ; the T2 distribution revealed the water states and migration in wood drying, also the bound water was slowly lost in the drying initial stage. The mass of different water states in juvenile wood during drying could be calculated according to peak areas of T2 distributing. Finally mathematical models for free water, bound water and the total water migration were developed in the drying process.