Toward a prediction of the phase behavior of polyamide blends

As we have reported recently, the application of association models has provided a theoretical basis for the calculation of the free energy changes and phase diagrams of binary polymer blends in which hydrogen bonding plays a significant role. Here we report theoretical calculations of spinodal phase diagrams of a series of polyisophthalamide-polyether blends and compare the predictions with experimental observations of the miscibility of these polymer blend systems. The general agreement between theory and experiment is very encouraging and has important ramifications to discussions of polymer-induced crystallnity, the minimum number of hydrogen bonding sites necessary to ensure significant molecular mixing, and the effect of hydrogen bonding on the breadth of “miscibility windows.”