Statistical thermodynamics evaluation of polymer-polymer miscibility

摘要

The Simha and Somcynsky (S\u2013S) statistical thermodynamics theory was used to compute the solubility parameters as a function of temperature and pressure [\u3b4 = \u3b4(T, P)], for a series of polymer melts. The characteristic scaling parameters required for this task, P*, T*, and V*, were extracted from the pressure\u2013temperature\u2013volume (PVT) data. To determine the potential polymer\u2013polymer miscibility, the dependence of \u3b4 versus T (at ambient pressure) was computed for 17 polymers. Close proximity of the \u3b4 versus T curves for four miscible polymer pairs: PPE/PS, PS/PVME, and PC/PMMA signaled the usefulness of this approach. It is noteworthy, that the tabulated solubility parameters (derived from the solution data under ambient conditions) propounded the immiscibility of the PVC/PVAc pair. The computed values of \u3b4 also suggested miscibility for polymer pairs of unknown miscibility, namely PPE/PVC, PPE/PVAc, and PET/PSF. In recognizing the limitations of the solubility parameter approach (the omission of several thermodynamic contributions), these preliminary results are auspicious because they indicate a new route for estimating the miscibility of any polymeric material at a given temperature and pressure.