DERIVATION OF ACCURATE GLASS TRANSITION TEMPERATURES BY DIFFERENTIAL SCANNING CALORIMETRY.

This paper desccribes how a simple treatment of DSC data gives 'equilibrium' values of T//g, which are independent of the heating rate. By contrast, the rate of cooling (annealing) through the transition region has a well defined effect on the glass temperature and quantitative data are given for this and also for the specific heat increment at T//g. In experiments, anionic PS was used. It is demonstrated that the transformation of DSC data to enthalpy curves gives accurate values of T//g when the curves for the glass and liquid which lie outside the transition region are extrapolated to meet. The point of intersection is T//g, and this is independent of the DSC heating rate unlike the directly recorded curves.