Comment on “Determination of Nucleus Density in Semicrystalline Polymers from Nonisothermal Crystallization Curves”

Abstract

Besides orientation effects induced by flow, mechanical and optical properties of semicrystalline polymers are strongly affected by the spherulite size, hence the nucleation density. Therefore, tools to predict nucleation density and to relate it to the final mean spherulite size in processed plastic parts are technologically important. Menyhárd et al.1 presented a method for determining the nucleation density in nonisothermal crystallization experiments in the absence of flow using two sets of experimental data: the spherulite growth rate measured in polarized optical microscopy experiments (POM) at different temperatures and the bare nonisothermal DSC thermogram at a prespecified cooling rate. Before discussing this work, it must be mentioned that a procedure for dealing with this issue was published by the present author in 2002 for isothermal DSC experiments2 and in 2003 for nonisothermal experiments, including the application to real processing conditions in the absence of flow.3 Errors resulting from calibration effects, the sample thermal resistance, and heat released during isothermal, nonisothermal, and shear-induced crystallizations were also considered.4,5