Heat capacity of linear high polymers

Abstract The molar heat capacity of a 45:55% copolymer of ethylene and tetrafluoroethylene has been measured from 80 to 340 K by the use of an adiabatic calorimeter, to an accuracy of 0.3%. The results are found to be in close agreement with values calculated from the known optical lines of related polymers and the Tarasov model; they are also analysed together with the available data on polyethylene and four other fluoropolymers, showing that the principle of additivity for heat capacities is generally valid to within 2%. The logical relations between these two phenomenological frameworks and their resultant implication on the effective one-dimensional force constant of the carbon backbone are discussed at some length.