聚酰亚胺渗透汽化膜的研究(Ⅳ) 模型研究膜材料性质及膜中传质行为

Study on the polyimide membranes for pervaporation(Ⅳ) The transfer behavior investigation of steam permeates in PI membranes by transport modeling

依据改进的Scatchard-Hildebrand模型、Flory-Huggins理论、线性粘弹性理论,通过建立的传质模型计算298.15 K和308.15 K下,水蒸气小分子在PI膜中的吸附/脱附曲线.通过计算杨氏模量,研究了PI的玻璃化温度与杨氏模量的关系,以及PI结构对杨氏模量的影响.通过计算无限稀扩散系数D0,研究温度和PI的结构对无限稀扩散系数D0的影响.研究结果表明:模型能很好的预测水蒸气在PI膜中的传质行为,模型最大误差小于9%,平均误差小于4%,计算结果较好,进一步验证了所建模型的准确性.

A new transport model, which is based on modified Hildebrand - Scatchard model, Flory - Huggins theory and linear viscoelastic theory, was applied in this paper. Using this model, the sorption and desorption curves of steam in PI membranes were calculated under different temperatures as 298.15 K and 308.15 K. By calculating the parameter of E, the relation between the glass - transition temperature of PI and optimized parameter of E under different temperatures was studied. The influence of the structure of PI membrane on parameter of E was studied. The infinite dilution diffusion coefficient of steam in PI membranes was calculated. The influence of the temperature and the structure of PI membrane on the infinite dilution diffusion coefficient of steam in PI membranes were studied. It can be concluded that with temperature increasing, the infinite dilution diffusion coefficients of steam in PI membranes increase. Compared with experimental results, the maximum relative error was less than 9% and the average error was less than 4% comparing with experimental results, so the prediction results agree well with the experimental results.