纤维素中水分子扩散行为的分子模拟研究

Molecular Simulation of Water Diffusion Behavior in Cellulose

本文利用分子动力学方法对水在纤维素内的扩散吸附行为与吸附形态进行研究,计算了扩散系数、相互作用能。结果表明:水分子在无定形纤维素内的扩散能力较在空气中弱,扩散系数的数量级在10-11 m2/s。纤维素和水分子之间的静电作用对水分的扩散起到主要的束缚作用。随着纤维素内水含量增多,水分子在纤维素内部的扩散能力增强,扩散系数在含水量5%~6%、12%~14%两个阶段出现大幅跃升,分析影响因素后发现分别与水分子吸附形态改变、自由体积改变有关。

The diffusion and adsorption behavior of water in cellulose were studied by molecular dynamics method,and the diffusion coefficient and interaction energy were calculated.The results showed that the diffusion capacity of water molecules in amorphous cellulose was weaker than that in air,and the diffusion coefficient was 10-11 m2/s.The electrostatic interaction between cellulose and water molecules has a major binding effect on water diffusion.With the increase of water content in cellulose,the diffusion capacity of water molecules in cellulose increases,and the diffusion coefficient jumps significantly at the water content stages of 5%-6%and 12%-14%.After analyzing the influencing factors,it is found that it is respectively related to the change of adsorption morphology and free volume of water molecules.