利用核磁共振自由感应衰减曲线测定木材含水率

Determining wood moisture content by free induction decay of nuclear magnetic resonance

为定量测定木材含水率,以水分子中的质子为探针,利用核磁共振技术探究木材内部水分的变化情况。通过对胡桃木、红橡木和水曲柳解吸过程中,水分变化的核磁共振自由感应衰减曲线(FID)进行分析,发现木材的含水率与核磁共振的FID信号量高度线性相关,相关系数均超过0.99;因此,可以通过建立含水率与核磁共振FID信号的标准曲线实现木材含水率的核磁共振定量测量。同时,可以根据绝干木材的核磁共振FID信号量比较不同材种基本密度的大小。

Proton of water,as a probe,can be used to explore changes of moisture content in wood through nuclear magnetic resonance （NMR）.NMR provides a new way for the quantitative determination of wood moisture content （MC）.The changes of water in walnut,red oak and ash in desorption process were analyzed through free induction decay （FID） curve of nuclear magnetic resonance.The results showed that the relationship between wood sample MC and FID signal amplitude was highly linear,with R2 above 0.99.Therefore,wood moisture content can be measured with NMR by establishing a standard curve of wood MC and FID signal amplitude.Also the basic density of different wood species can be compared through FID signal intensity of dried wood.