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The problem of the solvent influence on the determination of polymer-polymer interaction parameters by inverse gas chromatography (IGC) has been reexamined in the light of a phenomenological approach recently proposed. Experimental data previously reported by different authors have been analyzed with this new alternative. Two main conclusions can be inferred. First, there is not a significant difference between the results of such an analysis and those obtained with the aid of more sophisticated and timeconsuming procedures. Second, a correct selection of the probes can reduce the confidence intervals of the obtained polymer-polymer interaction parameters.

In this work, inverse gas chromatography has been used to calculate interaction energy densities of two polymer blends: poly(epichlorohydrin) (PECH)/poly(methyl acrylate) (PMA) and poly-(hydroxy ether of Bisphenol A) (phenoxy, PH)/poly(vinyl methyl ether) (PVME) at different temperatures. An approach based on the lattice fluid theory has been used in an attempt to eliminate the well-known probe dependence of the thermodynamic parameters calculated by IGC. In the two polymer blends under study, the above mentioned data analysis seems to be unable to remove the probe dependence. However, it allows the calculation of an average characteristic interaction energy density * which can be used in the calculation of the interaction energy density B, its enthalpic and entropic components, and the interaction energy density related to the second derivative of the free energy, Bac. The thermodynamic properties so calculated are in good agreement with those obtained from a phenomenological and simpler data analysis.

Amorphous blends of poly(viny1 methylether) (a, = 63 OOO and M n = 37 OOO) and a copolymer of bisphenol A and epichlorohydrin (M, = 50400 and Mn = 18000) were found to be miscible over the complete range of compositions at temperatures below 420 K. At higher temperatures, blends separate into two phases, giving a LCST-type phase diagram. Heats of demixing and excess heat capacity of a 50:50 blend have also been measured by DSC. The r e s u b have been interpreted in terms of the equation-of-state theory and compared with predictions of a recent model proposed by ten Brinke and Karasz for blends which have direction-specific interactions.