Equilibrium melting parameters of poly(ethylene terephthalate)

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.