Analysis of non-isothermal polymer crystallization at constant scan rates based on the Avrami model

When polymer crystallization is initiated by an instantaneous athermal nucleation and controlled by two-dimensional secondary nucleation on the growth face, for crystallization from the melt upon cooling at a constant scan rate beta, an analysis based on the Avrami model reveals that a plot of beta/(Delta T-peak)(2) = beta/(T-M(0) - T-peak)(2), in which T-peak represents the peak temperature of crystallization rate and T-M(0) the equilibrium melting point, is nearly equivalent to that of the inverse of crystallization half-time tau(1/2) and peak time tpeak, which are obtained from isothermal crystallization and used as a measure of crystal growth rate. Therefore, a plot of beta/(Delta T-peak)(2) against T-peak at different scan rates can be utilized to examine the temperature dependence of the crystal growth rate in the same way as that of tau(1/2) and tpeak obtained under isothermal conditions at different temperatures. The applicability was confirmed via numerical calculations and experiments using poly(vinylidene fluoride) and poly (butylene terephthalate). The agreement of the temperature dependence estimated by the plot of beta/(Delta T-peak)(2) was much better than that of beta/(T-peak)(2) used in the well-known Kissinger plot.

Automated summary

In this study, a new method for examining the temperature dependence of crystal growth in polymer crystallization was proposed, utilizing the Avrami model. Parameters obtained from isothermal crystallization were used to evaluate crystal growth rate. The applicability of this method was confirmed through numerical calculations and experimental studies.