Thermodynamics of polyvinyl chloride solutions: II. Solutions in cyclopentanone

Six samples of polyvinyl chloride (PVC) ranging in molecular weight from 23,200 to 155,400, were used to determine in cyclopentanone the intrinsic viscosities, molecular weights, and the polymer-solvent interaction parameters over a wide range of temperatures. The solutions were found to behave normally and to exhibit no evidence of “aggregate” formation. The molecular weights obtained were independent of temperature and agreed well with those measured in cyclohexanone. The interaction parameters observed were independent of concentration but were 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 the temperature. From the temperature coefficient of the interaction parameter, it was deduced that, above a molecular weight of ca. 13,000, the heats of mixing of completely amorphous PVC with cyclopentanone as well as the heats of dilution should be exothermic.