Merlonghi Lorenzo, Giacinti Baschetti Marco, De Angelis Maria Grazia
Department of Civil, Chemical, Environmental and Material Engineering (DICAM), Alma Mater Studiorum-Università di Bologna, Via Terracini 28, 40131 Bologna, Italy.
DPI, P.O. Box 902, 5600 AX Eindhoven, The Netherlands.
Membranes (Basel). 2025 Mar 2;15(3):76. doi: 10.3390/membranes15030076.
The description of gas permeation across heterogeneous materials has been studied with many methods, mainly focusing on composites with high aspect ratios and low filler volume fractions. In the present work, the extension of these approaches to semicrystalline polymers is studied, considering a wide range of crystalline volume fractions to tackle applications ranging from membranes to barrier materials. A numerical approach focused on tortuosity effects related to the presence of impermeable crystalline domains was considered. Algorithms based on random sequential adsorption and Voronoi tessellation were used to reproduce the morphology of semicrystalline polymers. The flux reduction across the microstructures generated due to the presence of impermeable crystals was calculated by solving local mass balance through a finite volume method. Using this strategy, it was possible to investigate the effect of crystallites' arrangement, size distribution, orientation and shape on the relative permeability and the tortuosity of semicrystalline membranes. The results were analyzed considering existing macroscopic models and new analytical equations were proposed in order to account on such morphological effects for the prediction of the tortuosity in semicrystalline polymers.
人们已经用多种方法研究了气体在非均质材料中的渗透，主要集中在高长径比和低填料体积分数的复合材料上。在本工作中，研究了将这些方法扩展到半结晶聚合物的情况，考虑了广泛的结晶体积分数，以解决从膜到阻隔材料等各种应用问题。考虑了一种关注与不可渗透结晶域存在相关的曲折效应的数值方法。基于随机顺序吸附和沃罗诺伊镶嵌的算法被用于再现半结晶聚合物的形态。通过有限体积法求解局部质量平衡，计算了由于不可渗透晶体的存在而导致的微结构通量降低。使用这种策略，可以研究微晶的排列、尺寸分布、取向和形状对半结晶膜相对渗透率和曲折度的影响。考虑现有的宏观模型对结果进行了分析，并提出了新的解析方程，以便在预测半结晶聚合物的曲折度时考虑这种形态效应。
