中文摘要：

以自由体积理论为基础,利用基于基团贡献法的格子-流体（GCLF）状态方程计算高分子供溶剂扩散的有效自由体积,进而提出改进的高分子-溶剂体系扩散系数模型。模型中与高分子相关的参数均可由基团贡献法确定,可用于预测已知分子结构的高分子中的溶剂扩散系数。计算了8种有机溶剂和6种高分子组成的体系的无限稀释扩散系数和溶剂自扩散系数,与实验值保持良好一致。基于空穴自由体积在高分子总自由体积中所占比例在微观和宏观上应相等的观点,用正电子湮没（PALS）实验结果验证改进方法的合理性。

英文摘要：

Based on the free-volume theory,the group contribution lattice-fluid （GCLF） equation-of-state （EOS） was employed to determine the effective free volume provided by polymer for solvent diffusion.And thus a modified diffusion coefficient model was proposed for polymer-solvent systems.Since all the parameters related to polymer can be calculated by group contributions,this model can be used to predict solvent diffusion coefficients in polymers with molecular structures as the input.Calculations of infinite dilution diffusion coefficients and solvent self-diffusion coefficients were consistent with experimental data for eight organic solvents in six polymers.In addition,results form positron annihilation lifetime spectroscopy （PALS） measurements proved the reliability of the modification,on the basis that the ratio of the hole free volume to the total free volume in polymer from microscopic view should be equal to that from macroscopic view.