Abstract: A mathematical model is proposed for predicting small molecule solvent diffusion coefficients in amorphous glassy polymers, based on free volume theory that is suitable for rubbery polymers, and with the consideration of the plasticization effect induced by the penetrant. Because this model uses the identical conceptual framework in which free volume theory is derived for solvent diffusion in rubbery polymers, parameters used in free volume theory remain valid for this work. Only one parameter is introduced to describe the plasticization effect, and it can be easily estimated by thermodynamic theory about the glass transition temperature depression. Therefore, no adjustable parameters appear in this expression, resulting in its usefulness in prediction. Comparison of the diffusion coefficients calculated by this new model with the present experimental data, including benzene, toluene, ethylbenzene in polystyrene (PS) and poly(methyl methacrylate) (PMMA) are performed, calculation results in this study are in good agreement with experimental data, for the correct estimation of the hole-free volume change above and below the glass transition.

摘要： 以自由体积理论为基础 ,提出改良的玻璃态高分子中溶剂扩散系数的数学模型 .模型推导过程中考虑了溶剂可塑化效应对高分子凝聚态的影响 ,并以明确的物理概念计算玻璃态聚合物的自由体积 .对橡胶态适用的自由体积参数在此模型中保持有效 ,所引入的表达溶剂可塑化效应的唯一参数 β可以通过计算玻璃化温度来确定 .所以 ,本模型中无可调节参数存在 ,具有完全可预测性 .以芳香族溶剂苯、甲苯、乙苯在玻璃态聚苯乙烯和聚甲基丙烯酸甲酯中的扩散系数为例对模型进行验证 ,理论计算结果和实验值取得良好一致