利用核磁共振测定木材吸着水饱和含量

Bound Water Content in Saturated Wood Cell Wall Determined by Nuclear Magnetic Resonance Spectroscopy

利用核磁共振(NMR)技术研究了室温与-3℃条件下5种树种木材内水分质子的自旋-自旋弛豫时间(T2)特性,室温下各树种木材试样T2弛豫时间特性的不同是由木材微观构造导致的.通过对比冷冻前后各树种试样的信号反演峰面积,确定了其吸着水饱和含量,樟子松38.3%,杉木38.5%,杨木36.0%,白蜡木35.6%,轻木47.6%,均高于通过吸湿外推法估算数值,与溶剂排出法、多孔板法、离心法等实测法获得的吸着水饱和含量的结果相近,核磁共振技术可作为木材内吸着水含量快速测定的实验方法.

1H spin-spin relaxation time（T2） of water in 5 species of wood was measured by nuclear magnetic resonance（NMR） spectroscopy at room temperature and-3℃, which is thought to be related to the anatomical structure of the wood. The bound water content within swollen cell wall was determined by comparison of the inversion peak area before and after frozen treatment： Pinus sylvestris 38.3%, Cunninghamia lanceolata 38.5%, Populus sp. 36.0%, Fraxinus excelsior L. 35.6% and Ochroma pyramidale 47.6%. The bound water contents determined by NMR spectroscopy were apparently higher than those obtained by the conventional extrapolation methods, but similar to the results obtained by the solute exclusion method, porous plate method, centrifugal dewatering method. It is concluded that NMR may provide a rapid and non-destructive way to determine bound water content in wood.