Evaluation of the isoconversional approach to estimating the Hoffman-Lauritzen parameters from the overall rates of non-isothermal crystallization of polymers

The isoconversional approach proposed by Vyazovkin for evaluating the Hoffman-Lauritzen parameters from overall rates of non-isothermal crystallization was critically applied to two new and fast crystallizing polymers, poly(propylene terephthalate) and poly(butylene naphthalate), which are used for the production of fibers. Non-isothermal crystallization data were corrected for the effect of the thermal lag and the effective activation energy as a function of temperature was calculated using the method of Friedman. The estimated Hoffman-Lauritzen parameters. U* and K-g, were consistent with corresponding values from isothermal crystallization experiments obtained either from DSC measurements or using polarized optical microscopy (POM). It was found that the proposed method could simulate the experimental data very well, and the temperature interval under consideration did not allow the detection of any critical breakpoints denoting regime transitions.