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

Abstract

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 β, an analysis based on the Avrami model reveals that a plot of β/(ΔTpeak)2=β/(TM0−Tpeak)2, in which Tpeak represents the peak temperature of crystallization rate and TM0 the equilibrium melting point, is nearly equivalent to that of the inverse of crystallization half-time τ1/2 and peak time τpeak, which are obtained from isothermal crystallization and used as a measure of crystal growth rate. Therefore, a plot of β/(ΔTpeak)2 against Tpeak at different scan rates can be utilized to examine the temperature dependence of the crystal growth rate in the same way as that of τ1/2 and τpeak 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 β/(ΔTpeak)2 was much better than that of β/(Tpeak)2 used in the well-known Kissinger plot.