Department of Forest Products Technology, School of Science and Technology, Aalto University, P.O. Box 16300, FIN-00076 Aalto, Finland.
Biomacromolecules. 2010 Aug 9;11(8):2161-8. doi: 10.1021/bm100547n.
Ultrastructural alterations of fresh wood caused by initial drying were compared to changes incurred during drying of never-dried wood pulp fibers of different macromolecular composition. Drying induced inaccessibility of a native wood sample exhibited remarkable similarity to wood pulp samples of different lignin contents. The results suggest that the supramolecular rearrangements in native wood matrix upon dehydration are qualitatively identical to the well-known changes occurring in pulp fibers after drying, although the changes are considerably different in quantity. The alterations were observed and quantified by monitoring the conversion of accessible deuterium exchanged OH groups in fresh wood and wood pulp fibers to inaccessible, reprotonation resistant OD groups during drying. The deuteration/FT-IR measurements correlated well with the water retention measurement of the pulp samples. Irreversible reduction of water retention due to the supramolecular changes implies reduced accessibility of wood polymers in various chemical and mechanical treatments, such as enzymatic conversion of biomass or preparation of cellulosic nano-objects for diverse applications.
新鲜木材在初始干燥过程中产生的超微结构变化与从未干燥过的不同高分子组成的木浆纤维在干燥过程中产生的变化进行了比较。干燥导致天然木材样品的不可接近性，与不同木质素含量的木浆样品表现出显著的相似性。结果表明，在脱水过程中天然木材基质中的超分子重排与众所周知的在干燥后发生在纸浆纤维中的变化在质量上是相同的，尽管在数量上有很大的不同。通过监测新鲜木材和木浆纤维中可交换氘化 OH 基团转化为不可接近的、抗再质子化的 OD 基团的过程，观察到并量化了这些变化，这是在干燥过程中发生的。氘化/FT-IR 测量与纸浆样品的保水率测量相关良好。由于超分子变化导致的水Retention 的不可逆减少意味着木材聚合物在各种化学和机械处理中的可及性降低，例如生物量的酶转化或用于各种应用的纤维素纳米物体的制备。
