Department of Forest Products Technology, Helsinki University of Technology, Finland.
Biomacromolecules. 2010 Feb 8;11(2):515-20. doi: 10.1021/bm901268j.
The impact of drying on the ultrastructure of fresh wood was studied by deuterium exchange coupled with FT-IR analysis. This fundamental investigation demonstrated that water removal leads to irreversible alterations of the wood structure, namely, supramolecular rearrangements between wood polymers. The deuteration of fresh wood was shown to be fully reversible by a subsequent exposure of the deuterated sample to water (reprotonation). Therefore, the presence of any OD groups in deuterated and then dried wood samples after reprotonation is a clear indicator of reduced accessibility. The extent of changes was affected by drying temperature and relative humidity. Application of this methodology for the evaluation of chemical pulp sample (reference material) resulted in similar response, only more pronounced. Two hypothetical alternatives were proposed for accessibility reduction in dried wood: (i) irreversible aggregation of cellulose microfibrils and (ii) irreversible stiffening of the hemicellulose/lignin matrix that extensively swells when exposed to water.
通过氘交换结合傅里叶变换红外分析研究了干燥对新鲜木材超微结构的影响。这项基础研究表明，水分的去除会导致木材结构的不可逆变化，即木材聚合物之间的超分子重排。通过随后将氘化样品暴露于水中（质子化），证明新鲜木材的氘化是完全可逆的。因此，在质子化后干燥的氘化木材样品中存在任何 OD 基团是可及性降低的明确指标。干燥温度和相对湿度会影响变化的程度。该方法在评估化学浆样品（参考材料）时得到了类似的响应，只是更为明显。对于干燥木材中可及性降低，提出了两种假设性的替代方案：（i）纤维素微纤维的不可逆聚集和（ii）半纤维素/木质素基质的不可逆硬化，当暴露于水时，该基质会广泛膨胀。
