Phase Behavior of EVAL Polymers in Water-2-Propanol Cosolvent
Phase Behavior of EVAL Polymers in Water-2-Propanol Cosolvent
复制标题
EVAL 聚合物在水-2-丙醇共溶剂中的相行为
作者：
T. Young;L. Cheng;C. Hsieh;Leo
用两种非溶剂（水和2-丙醇）作为共溶剂体系，确定了半结晶聚乙烯醇（EVAL）的等温相图。确定了60℃时液相图中液-液脱混和结晶诱导胶凝的位置。利用三个二元相互作用参数（χij）和一个三元相互作用参数（χT），尝试将实验结果与基于改进的Flory - Huggins理论的三元解预测相关联。如果忽略三元相互作用参数，理论预测和实验数据之间没有很好的一致性。但当考虑三元相互作用参数时，可以得到改进。最优值约为−1.7 + 0.5φ2 + 1.0φ3。因此，当二元参数不能充分描述相行为时，引入三元相互作用参数是必要的。
Isothermal phase diagrams for semicrystalline poly(ethylene-co-vinyl alcohol) (EVAL) using two nonsolvents (water and 2-propanol) serving as a cosolvent system have been determined. The locations of the liquid−liquid demixing and the crystallization-induced gelation in the phase diagrams at 60 °C were identified. Attempts were made to correlate the experimental findings with predictions on the basis of the modified Flory−Huggins theory for ternary solutions using three binary interaction parameters (χij) and one ternary interaction parameter (χT). No good agreement was found between the theoretical predictions and experimentally obtained data if the ternary interaction parameter was neglected. But an improvement can be obtained when a ternary interaction parameter is considered. The optimum value has been found to be approximately −1.7 + 0.5φ2 + 1.0φ3. Therefore, it is necessary to introduce the ternary interaction parameter when the binary parameters provide an inadequate description of phase behavior, b...