Thermodynamic properties of polystyrene and styrene

Abstract

A Tarassov function has been used to estimate the specific heat of polystyrene between 0° and 60°K. These data, together with published C_p data, have been used to calculate the entropy, enthalpy, and free energy of styrene and polystyrene from 0° to 298.16°K. The entropy of polymerization of styrene at 298.16°K. was found to be 26.69 cal./mole°.The thermodynamic function C_p/T versus T as calculated for polystyrene, increases to a maximum at 65°K. and then increases again at the glass transition temperature. The Tarassov function, which is shown to be useful in estimating the specific heat of amorphous polymers, should be combined with a T³ Debye function to yield more accurate c_v data at low temperatures. The number of classically vibrating units per repeating unit of polystyrene was found to be 6.57. The difference C_p – C_v was calculated at 273°K. and found to be 2.0 cal./mole°.