Heat Capacity of Dilute Polymer Solutions

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Abstract
Flory's treatment of the excluded volume integral for pairs of segments of polymer chains is extended to include temperature dependence of the enthalpy and entropy of mixing. The heat capacity term thereby introduced is evaluated from the known critical solution temperatures for polyisobutylene–benzene and polystyrene–cyclohexane. The ratio C ¯ p,1 E / S ¯ 1 E at infinite dilution is calculated to be −3.1 and −4.1, respectively. A less accurate estimate of this quantity for polystyrene–decalin is employed in an analysis of data obtained by Berry. It is shown that partial draining effects are not as large as previously deduced, and that the results for this system are rationally interpreted by inclusion of temperature dependent thermodynamic functions for the mixture.