School of Tea and Food Science and Technology, Anhui Agricultural University, Hefei 230036, China.
Department of Applied Chemistry, School of Science, Anhui Agricultural University, Hefei 230036, China.
Carbohydr Polym. 2019 Apr 15;210:322-331. doi: 10.1016/j.carbpol.2019.01.087. Epub 2019 Jan 28.
The contribution of different states of adsorbed water to the sub-T dynamics of cellulose was investigated by means of dielectric spectroscopy in couple with LF-NMR. The distribution and hydration state of adsorbed water in cellulose were determined by LF-NMR, based on which the role that different state of adsorbed water plays in typical secondary dielectric relaxations is discussed in detail. The variation of the dynamic characteristics of these relaxations suggested that three states of bound water present in moist cellulose, including tightly bound, non-freezable loosely bound, and freezable loosely bound water. It was discovered that different state of adsorbed water has obviously different contribution to these relaxations and the role that a certain state of bound water plays in different relaxations also varies. For cellulose with very high moisture content, an additional relaxation due to the dynamics of interfacial ice-like water was also observed.
采用介电谱法与 LF-NMR 相结合的方法研究了不同吸附态水对纤维素亚松弛动力学的贡献。通过 LF-NMR 确定了纤维素中吸附水的分布和水合状态，在此基础上详细讨论了不同吸附态水在典型次级介电松弛中所起的作用。这些松弛的动态特性的变化表明，在潮湿的纤维素中存在三种结合水状态，包括紧密结合的、不可冻结的松散结合的和可冻结的松散结合的水。研究发现，不同吸附态的水对这些松弛有明显不同的贡献，而且某种结合态水在不同松弛中所起的作用也不同。对于水分含量非常高的纤维素，还观察到了由于界面冰状水的动力学引起的额外松弛。
