Some considerations on equation of state and phase relations: Polymer solutions and blends

Abstract

We review briefly the general assumptions underlying hole theories of the configurational thermodynamic functions for single and multiconstituent systems. From the original Simha-Somcynsky theory several important modifications have recently evolved. First, there is a revision of the combinatorial entropy originating from the mixing of segments and holes in the spirit of Huggins's theory. With consistent additional modifications of the configurational free energy, quantitatively significant consequences for certain aspects of phase equilibria can arise. Finally, allowance for nonrandom mixing of constituents species and holes has been made. We illustrate the theory's potentials first in terms of pressurevolume-temperature (PVT) data for high and low molar mass species and their miscible mixtures. The influence of PVT properties on the miscibility behavior of solutions and blends is examined next. Of particular concern are the connections between predictability of lower from upper mixing spinodals, pressure effects, and the binary interaction ,y-function.

Thermodynamics of Polymer Blends

“…Thus, for the systems without strong interactions, the binary parameters are well approximated by the geometric and algebraic averages. For example, for PS/PVME blends, the assumption S e ¼ S v ¼ 1 resulted in 0.1 % deviation for the experimental values of the cross-parameters (Xie et al 1992;Xie and Simha, 1997, "private communication"). In contrast, it is to be expected that for systems with strong intermolecular interactions such mixture rules may fail and experimental values for the cross-factors may have to be found.…”

Free Volume in Molten and Glassy Polymers and Nanocomposites

“…The studies not only collect information on the influence of P and T on the specific volume, density, compressibility, and other derivative properties, but in addition, using an adequate theory, they offer an insight into segmental interactions, segmental packing, the free volume, which in turn affects a host of properties, including thermodynamic equilibrium and nonequilibrium properties, such as cohesive energy density, solubility, viscosity, diffusivity, as well as the solid-state performance (i.e., physical aging, crystallization kinetics, etc.). For binary systems the PVT data analysis yields information about interactions between constituents: the polymeric matrix and entities dispersed in it: gas bubbles [Xie et al, 1992;Higuchi and Simha, 1996;Xie and Simha, 1997;Simha and Xie, 1998;Simha and Moulinié, 2000;Utracki and Simha, 2001b;Li et al, 2008], domains of immiscible polymers [Zoller and Hoehn, 1982;Jain et al, 1982;Maier et al, 1994;Srithawatpong et al, 1999;Utracki and Simha, 2001a], filler particles Simha et al, , 1986Papazoglou et al, 1989;Simha et al, 1989], or nanoparticles [Simha et al, 2001;Utracki et al, 2003;Nelson et al, 2004;Utracki and Simha, 2004;Bamji et al, 2005].…”

Equations of State and Free‐Volume Content

“…Given a reliable PVT description of polymer melts and their mixtures, the equilibrium behavior of a polymer with a gas phase was examined [Xie et al, 1992]. During the last 20 years, studies of gas polymer sorption enjoyed great advances on two fronts:…”