Thermal analysis of lamellar thickening during isothermal crystallization

Abstract

Abstract The tickening of lamellar crystals occurring during isothermal crystallization has been explained as the result of molecular fractionation induced by crystallization. The feasibility of this theory is confirmed by the analysis of the DSC melting curves of a Marlex 50 polymer as a function of the crystallization time. The melting curves are recorded for meltcrystallized samples and solution grown crystals. In contrast with the crystallization from melt, the melting peak for solution grown crystals remains practically at a constant temperature, in the range of the crystallization time studied. Obviously, this corresponds to the observed constant fold period. This molecular fractionation theory is compared with the one of H OFFMANN and P ETERLIN .