A comparative study of the kinetic theories of the glass transition phenomenon in high polymers

The effect of thermal history on the glass transition temperature (T_g) of poly(vinyl chloride) was studied. The parameters like the hole energy (E_h), the activation energy for the disappearance of holes (E_j), the activation enthalpy for the structural relaxation (Δh1* and Δh2*) and the activation energy for the glass transition process (E) were calculated. The increase of E_h value with the increase in T_g value shows that there exists a holesize distribution. The E_j (26.9 ± 0.5 kcal/mol) value calculated according to Wunderlich's treatment, the Δh1* (27.8 ± 0.6 kcal/mol) value obtained by Moynihan's procedure and the E (35.3 kcal/mol) value from Barton-Critchley's method agree well with one another in the poly(vinyl chloride) system. The Δh2* quantity, obtained through Moynihan's formulations, increase as the rate of heating was increased, a result similar to the variation of E_h value with the rate of heating.