摘要
在一些玻璃态聚合物中,溶剂分子的运移行为会呈现出不同于经典Fick定律的Non-Fickian扩散性质,且该过程往往伴随着材料溶胀和大变形。类比热传导分析中的非傅里叶效应理论,本文采用双相滞后方法,即引入两个描述玻璃化转变过程中材料性能依赖于浓度的控制参数,以考察Non-Fickian型溶剂扩散与凝胶溶胀变形的行为特征。针对不同材料体系的一维柱状和二维板状凝胶溶胀理论模型,借助有限差分法进行控制方程数值求解,所得的计算结果表明,溶剂分子在这两种聚合物中的浓度分布显著区别于Fick扩散形式,材料溶胀部分与未溶胀部分之间存在着一个尖锐分界面,且该分界面移动速率近似为一个常数。同时,理论计算结果与现有实验结果的吻合度较好,这也进一步验证了双相滞后方法描述Non-Fickian扩散动力学的有效性和准确性。
In some glassy polymers,the transport behavior of solvent molecules exhibits non-Fickian diffusion features which are different from the classical Fick’s law,and this process is usually accompanied by swelling and large deformation of the material.In this paper,the characteristics of non-Fickian solvent diffusion and swelling deformation of gels are investigated by using a two-phase hysteresis method,which is analogous to the theory of non-Fourier effect in heat conduction analysis.In other words,two controlling parameters related to solvent concentration are introduced to describe the material properties during the glassy transition process.The governing equations for describing diffusion and swelling of different material systems,namely one-dimensional gel rod and a two-dimensional gel plate,are numerically solved by the finite difference method.Our obtained results show that the concentration distribution of solvent molecules in these two polymers is significantly different from that under the case of Fick diffusion.There is a sharp boundary between the swollen part and the non-swollen part,and its moving speed is approximately a constant.At meantime,the theoretical predictions are in good agreement with the existing experimental results,which further verifies the validity and ability of the two-phase hysteresis method to characterize the kinetics of Non-Fickian diffusion.
作者
李能
李旭
LI Neng;LI Xu(School of Science,Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics,Wuhan University of Technology,Wuhan 430070,China)
出处
《高分子通报》
CAS
CSCD
北大核心
2022年第5期77-85,共9页
Polymer Bulletin
基金
国家自然科学基金(11902229)
中央高校基本科研业务费专项资金(WUT:2020IB007)资助。
