Mean-field lattice equations of state: 4. Influence of pressure on the phase behaviour of the system polystyrene/cyclohexane
Mean-field lattice equations of state: 4. Influence of pressure on the phase behaviour of the system polystyrene/cyclohexane
复制标题
平均场晶格状态方程：4.压力对聚苯乙烯/环己烷体系相行为的影响
DOI：
10.1016/0032-3861(92)91101-7
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发表时间：
1992
期刊：
影响因子：
4.6
通讯作者：
R. Koningsveld
中科院分区：
文献类型：
--
作者：
L. V. Opstal;R. Koningsveld
混合自由焓的Flory-Huggins-Staverman表达式中相互作用项的压力依赖性可以借助于一般热力学关系式引入。本文以压力对聚苯乙烯/环己烷体系相行为的影响为例，研究了（δT δp）c在临界点的符号随压力和聚苯乙烯摩尔质量的增加而变化的情况，并以此作为该半唯象（SP）模型和修正的平均场格子气（MFLG）模型的检验案例。SP模型在描述相图的一部分和预测另一部分方面表现得非常好。相比之下，MFLG模型仅代表不同摩尔质量的聚苯乙烯样品的数据，如果混合物的参数之一是空穴浓度的函数。即使相互作用项是一个高度复杂的浓度函数，对所有样品的同时描述也只是定性的。
The pressure dependence of the interaction term in the Flory-Huggins-Staverman expression for the free enthalpy of mixing can be introduced with the aid of general thermodynamic relations. The peculiar pressure influence on the phase behaviour of the system polystyrene/cyclohexane, where the sign of (δT δp) c at the critical point changes upon an increase of pressure and molar mass of polystyrene, is taken as a test case for this semi-phenomenological (SP) model and for a modified form of the mean-field lattice-gas (MFLG) model published earlier. The SP model performs very well in describing one part of the phase diagram and in predicting another part. The MFLG model in contrast only represents data for polystyrene samples of different molar mass separately if one of the parameters for the mixture is made a function of the hole concentration. A simultaneous description for all samples is only qualitative even though the interaction term is made a highly complicated concentration function.