基于晶格理论的聚合物溶液活度模型

根据Gibbs-Helmholtz热力学基本关系式,结合溶液晶格模型推导出适合聚合物体系的活度系数模型,该模型方程含有结合项、剩余项和自由体积项。将其与Entropic-FV(EFV)、UNIFAC-FV及UNIFAC模型,同时用于预测14个由PIB、PS和PPO等聚合物与苯、甲苯和丁烷等溶剂组成的聚合物-溶剂体系中溶剂的活度,并与实验数据进行比较,活度的平均偏差分别为3．98%、6．61%、4．92%、19．19%。计算结果显示该模型的预测精度高于其它3种常用的聚合物、溶剂体系的溶剂活度模型。

A activity model for the prediction of solvent activities in polymer solutions

A simplified activity model for polymer solutions is developed from the thermodynamic relation in this work.The model in- cludes not only a combinatorial term and a residual term but also a free volume one.The calculated results differ significantly between the models with and without taking the free volume effect into consideration.The validity of this new method is demonstrated by compa- ring the estimated activities from the present model equation with those by the EFV,the UNIFAC-FV and the UNIFAC methods.The overall average absolute deviation of solvent activities in 14 polymer solutions was 6.61% for EFV,4.92% for UNIFAC-FV,19.19% for UNIFAC and 3.98% for the proposed model.It is shown that the new model can yield improved results over the other models and is able to describe the phase behavior for polymer solutions over a wide range of molecular weights,temperatures and densities.