Fennell Eanna, Kamphus Juliane, Huyghe Jacques M
Bernal Institute, University of Limerick, Castletroy, V94 T9PX Limerick, Ireland.
School of Engineering, University of Limerick, Castletroy, V94 T9PX Limerick, Ireland.
Polymers (Basel). 2020 Mar 7;12(3):609. doi: 10.3390/polym12030609.
The Flory-Rehner theoretical description of the free energy in a hydrogel swelling model can be broken into two swelling components: the mixing energy and the ionic energy. Conventionally for ionized gels, the ionic energy is characterized as the main contributor to swelling and, therefore, the mixing energy is assumed negligible. However, this assumption is made at the equilibrium state and ignores the dynamics of gel swelling. Here, the influence of the mixing energy on swelling ionized gels is quantified through numerical simulations on sodium polyacrylate using a Mixed Hybrid Finite Element Method. For univalent and divalent solutions, at initial porosities greater than 0.90, the contribution of the mixing energy is negligible. However, at initial porosities less than 0.90, the total swelling pressure is significantly influenced by the mixing energy. Therefore, both ionic and mixing energies are required for the modeling of sodium polyacrylate ionized gel swelling. The numerical model results are in good agreement with the analytical solution as well as experimental swelling tests.
水凝胶溶胀模型中自由能的弗洛里 - 雷纳理论描述可分为两个溶胀组分：混合能和离子能。传统上对于离子化凝胶，离子能被视为溶胀的主要贡献者，因此混合能被认为可忽略不计。然而，这一假设是在平衡状态下做出的，忽略了凝胶溶胀的动力学过程。在此，通过使用混合杂交有限元方法对聚丙烯酸钠进行数值模拟，量化了混合能对离子化凝胶溶胀的影响。对于单价和二价溶液，在初始孔隙率大于0.90时，混合能的贡献可忽略不计。然而，在初始孔隙率小于0.90时，总溶胀压力受到混合能的显著影响。因此，模拟聚丙烯酸钠离子化凝胶溶胀需要同时考虑离子能和混合能。数值模型结果与解析解以及实验溶胀测试结果吻合良好。
