Analysis of the thermodynamic compatibility of poly(vinyl chloride) and nitrile rubbers from inverse gas chromatography

The solubility parameter method was applied to an analysis of the solution thermodynamic data of several solutes (probes) in polymers obtained by inverse gas chromatography. Experimental data previously reported by different authors were analyzed. The polymers used as the stationary phases were poly(vinyl chloride) (PVC), two nitrile rubbers (NBRs), and PVC / NBR blends. From the retention volumes of the probes, the Flory-Huggins interaction parameters at infinite dilution were calculated. The interaction parameters, in turn, were related to the solubility parameters of the solutes and stationary phases. With a series of probes, the solubility parameters of PVC and NBRs were determined. Differences existed between the experimental values of the size-corrected free energies of solutions and the values calculated with solubility parameters. The differences were generally negative values. When these differences obtained from two NBR rubbers were plotted versus PVC, a correlation was found. Methods for obtaining the interaction parameters of polymer blends were examined. A modified plotting method gave a linear line and an interaction parameter between two polymers consistent with the results of the solubility parameters. (C) 2003 Wiley Periodicals, Inc.