Effects of thermal history on enthalpy relaxation in glasses 7. Thermal time constants

Experimental data on a single polymer sample indicate that the instrumental/sample Green function is essentially a Dirac delta function, with a time constant of 15 s. Distortions of scanned heat capacities over the glass transition temperature range, induced by this Green function, were deconvoluted and the deconvoluted data were found to be independent of heating = cooling rate (apart from temperature shifts), in accordance with expectations. The effects of a single thermal time constant on computed activation energies and different definitions of Tg are discussed. It is suggested that temperature calibration can be compromised by a nonzero thermal time constant.