聚合物浓溶液中气液平衡的估算──UNIFAC－FV模型参数考察

ESTIMATION OF VLE IN CONCENTRATED POLYMER SOLUTIONS ─THE STUDY OF MODEL PARAMETERS IN UNIFAC - FV MODEL

应用ＵＮＩＦＡＣ－ＦＶ模型估算了低密度聚乙烯一溶剂体系中以重量分率表示的溶剂亨利常数，Ｈ；”．以及低密度聚乙一溶剂和聚苯乙烯一溶剂中无限稀释的溶剂活度系数Ｏｉｃ．结果表明，通过调节ＣＩ，ＵＮＩＦＡＣ－ＦＶ模型能较好地估算Ｈ７和Ｄ７．估算溶剂亨利常数时，低密度聚乙烯一溶剂体系：芳烃取ＣＩ—１１，脂肪烃取ＣＩ—２·０，低密度聚乙烯一极性溶剂体系中ＣＩ随溶剂不同而变化；估算无限稀释的溶剂活度系数时，ＣＩ值随聚合物一溶剂体系而变，且模型估算误差较前者为大；参数ｂ值随ＣＩ和温度而变；对脂肪烃、环已烷和极性溶剂之Ｄ７的估算，ＵＮＩＦＡＣ－ＦＶ模型有待进一步改进．

The UNIFAC - FV model has been applied to predict the weight - fraction Henry's const ants (H7 ) and the infinite dilution activity coefficients (n7 ) of solvents low- density polythylene in (LDPE) polystgrene in PS in the temperature range of 100 to 250℃ By adjusting the number of external degrees of freedom per hydrocarbon molecule,C,,H7 is correlated with good agreement between the model and experimental data,and ac can be basically estimated by the model. In calculating H7, the values of C, are 1. 1 and 2. 0 for aromatic and aliphatic hydrocarbons in LDPE respectively,and are changed with the different polar solvents.While in calculating 'r,the values of C, vary with the types of solvents in PS and in LDPE. By adjusting a parameter, n: can also be calculated for cyclohexane,n - heptane and n - decane in PS and LDPE. The results show that model parameter. b will change with C, and temperature.The UNIFAC - FV model should further be improved for the estimation of ac, espacially for aromatic hydrocarbons,cyclohexane and pcial solvents in polymer solutions.