The equilibrium melting temperature, volume, and enthalpy and entropy changes on melting of poly(ethylene terephthalate) have been analyzed and heats of fusion have been newly measured with an automated scanning calorimeter to yield the following data: 553°K, 16.9 cm3/mole, 2.69 kJ/mole, and 48.6 J/deg/mole, respectively. A more detailed discussion of annealed samples obtained from etched starting materials shows that the density of the noncrystalline regions may be variable.

The heat capacity of polyethylene from 0 K to 600 K is reviewed using measurements on 46 samples reported in the literature. The crystallinity dependence is evaluated critically and a set of recommended data for completely crystalline and amorphous polyethylene is derived. Entropy, enthalpy, and Gibbs energy functions are calculated. Polyethylene can serve as a standard material for the thermodynamic functions of a simple linear macromolecule. This paper is the second in a series which will ultimately cover all heat capacity measurements on linear macromolecules.

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