Thermodynamics of polyvinyl chloride solutions. I. Solutions in cyclohexanone

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Abstract
Five samples of polyvinyl chloride, ranging in molecular weight from 23,200 to 155,400, were used to determine in cyclohexanone the intrinsic viscosities, molecular weights, and the polymer-solvent interaction parameters over a wide range of temperatures. Under all conditions studied, no “anomalous” solution behavior was observed, nor has evidence been detected for the presence of polymer “aggregates” in solution. The molecular weights of the samples were found to be independent of temperature between 17.5° and 106.5°C. The interaction parameters proved to be independent of concentration, but to be dependent on temperature and molecular weight. Again, the intrinsic viscosities as functions of molecular weight were found to follow the Mark-Houwink relation between 20° and 60°C with a constant a, but with a K linearly dependent on T. From the temperature coefficient of μ, λ, it was shown that above M2 = ca. 6200 the heats of mixing of completely amorphous polymer with solvent as well as heats of dilution should be exothermic, and these conclusions are in accord with observation. Further, the λ's obtained from osmometry agree with those obtained microcalorimetrically, thus confirming the contentions and validity of Maron's theory of polymer solutions.