A kinetic model is proposed for the absorption of water in polymers. The process of bonding-debonding water molecules is described by two opposite reactions with different rate constants, and the key role of the concentration of traps by hydrogen bonding in the polymer matrix is highlighted. These three parameters are combined such that an equation is obtained that generalizes the model proposed by Carter and Kibler, with an additional, crossed, term. Numerical application is performed for the diffusion-absorption of water in a plane polymer sheet, and the parameter ranges where a quasi-Fickian water uptake curve is obtained are defined. The associated apparent diffusivity is shown to obey a hyperbolic variation with equilibrium water uptake for homologous series of polymers, which is in agreement with previous experimental observations.

提出了用于吸收聚合物中水的动力学模型。通过两个速率常数不同的相反反应描述了水分子键合-键合的过程，并着重指出了通过氢键在聚合物基体中捕集阱的浓度的关键作用。将这三个参数组合在一起，就可以得到一个方程，该方程可以概括由Carter和Kibler提出的模型以及一个附加的交叉项。对水在平面聚合物片材中的扩散吸收进行数值应用，并定义了获得准菲克吸水曲线的参数范围。对于相关的聚合物系列，相关的表观扩散率显示出服从平衡水吸收的双曲线变化，这与先前的实验观察一致。