A Theoretical Model of Relaxation in the Glass Transition Region: Application to the Temperature-Modulated DSC
نویسنده
چکیده
A single relaxation time model is used to describe the kinetics of enthalpy relaxation of glassforming systems subjected to a temperature modulated cooling or heating. There are two time scales of the measurement, a short one fixed by the modulation frequency and a slow one, determined by the average heating or cooling rate. It is demonstrated that the maximal respond of the system appears when the relaxation time is about 20% of the modulation period. Our computed data are in good agreement with the existing experimental data on polystyrene relaxation. It is demonstrated that the activation energy is overestimated considerably when determined from the slope of an Arrhenius plot (a log-lin plot of frequency against the reciprocal temperature).
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