Modeling and computation of solvent penetration in glassy polymers

本提案的主要目标是溶剂在玻璃聚合物中渗透的计算模型。对于大多数工程应用来说，菲克定律准确地描述了扩散过程，但是在玻璃化转变温度附近的玻璃化聚合物中，菲克定律失败了。在玻璃化转变温度附近，当低分子量溶剂扩散到玻璃化聚合物中时，使后者发生橡胶-玻璃相转变。扩散过程遵循非菲克行为。经典的菲克式扩散称为情形一扩散，而玻璃聚合物中的扩散称为非菲克式的“情形二扩散”。一个典型的系统进行情况II扩散是聚甲基丙烯酸甲酯（PMMA）和甲醇为例。例如，在制药和汽车工业中，对经历案例II扩散的聚合物进行建模是特别感兴趣的。由于扩散在许多工业和生物过程中的重要性，从各种角度和技术进行完整的检查是必要的。手头的一个工具是计算建模，这是本项目的目标。在此基础上，建立一个包罗万象的理论模型。因此，非常具有挑战性的非菲克行为建模是本项目的主要任务之一。这一雄心勃勃的理论的数值实现将随后完成，以便从工程或生物力学中计算出不同的典型应用模型。

The main goal of this proposal is the computational modeling of solvent penetration in glassy polymers. For most engineering applications, Fick s law accurately describes diffusive processes, but one of the applications where it miserably fails is in glassy polymers near the glass transition temperature. In the vicinity of the glass transition temperature, when a low molecular weight solvent diffuses into a glassy polymer, the latter is caused to undergo a rubber-glass phase transition. The diffsive process follows non-Fickian behavior. Whereas the classical Fickian diffusion is referred to as case I diffusion, diffusion in glassy polymers is known as non-Fickian „case II diffusion“. A typical system undergoing case II diffusion is polymethylmethacrylate (PMMA) and methanol, for example.Modeling polymers which undergo case II diffusion is of particular interest in pharmaceutical and automotive industries, for example. Due to the importance of diffusion in many industrial and biological processes, a complete examination from a variety of perspectives and techniques is necessary. One tool at hand is the computational modeling at which this project aims. Hereby, an all-embracing theoretical model is to be set up extending existing approaches. Thus the very challenging modeling of non-Fickian behavior is one main task of this project. The numerical implementation of this ambitious theory is to be done subsequently in order to computationally model distinct typical applications from engineering or biomechanics.