HEAT-CAPACITY OF POLYMER MELTS FROM THE POLYMER CHAIN-OF-ROTATORS EQUATION OF STATE

Recently, the chain-of-rotators equation of state derived from the rot ational partition function was extended to polymers. Values of the thr ee equation of state (EOS) parameters were obtained from fitting with experimental pressure-volume-temperature data and the parameters were correlated with the structure of the polymer repeat unit. In this arti cle, the residual molar heat capacity derived from an EOS is added to the ideal gas heat capacity from Benson's group contribution method to obtain the polymer molar heat capacity at constant pressure, C-p. Pre dictions from the polymer chain-of-rotators (PCOR) using correlated pa rameters are compared with those obtained from PCOR, Sanchez-Lacombe, Flory-Orwoll-Vrij, and the perturbed-hard sphere chain equations of st ate using parameters fitted from experimental data. Deviations of calc ulated C-p from the formula of van Krevelen for liquid polymers are li kewise presented. With the correlations developed for its parameters, the PCOR offers the advantage of predicting the C-p for polymer melts from just the knowledge of the polymer's structure. (C) 1998 John Wile y & Sons, Inc.