Validity of kinetic predictions for polymer crystallization from molten and glassy states: the case of...

The crystallization of poly(p-dioxanone) (PDX) was examined under different regimes - cooling of a melt, heating from the glassy state, and isothermal annealing reached either from the melt or from the glass. In addition to differential scanning calorimetry (DSC) measurements, supplemental characterization was performed using Raman spectroscopy, thermogravimetry, and optical microscopy. The comparison of the hot and cold crystallization data revealed distinct differences in the PDX crystallization behavior, governed by the presence/amount of nuclei generated on the applied thermal path. The kinetic analysis of the crystallization data employed the extended autocatalytic model combined with Hoffman-Lauritzen or Arrhenius rate expressions. Both frameworks fitted the data well, but their predictive accuracy depended strongly on how the temperature-dependent nucleation K_g(T) and growth E(T) activation energies were implemented (an improvement of the existing models was suggested, based on compensation via the addition of a continuous temperature dependence of the pre-exponential factor A(T)). Predictions of isothermal crystallization from non-isothermal kinetics were only reliable when the nucleation state of the system was appropriately reproduced, underscoring the limitations of using thermal proximity alone as a predictor.