Abstract
The enthalpy relaxation process was analyzed for the engineering plastics, such as poly (ether sulfone), poly (ether imide), polysulfone and poly (ethylene terephthalate). In order to compare the rate of enthalpy relaxation, the enthalpy relaxation time at half of initial excess enthalpy (τ1/2) was evaluated at each annealing temperature (Ta). From the relationship between log τ1/2 and Tg-Ta, the rate of enthalpy relaxation was estimated. It was found that the rate of the engineering plastics was faster than that of polystyrene. The ether bond of the main chain of these engineering plastics seems to rotate easily in the glassy state.
