Crystallization kinetics of poly(trimethylene terephthalate) : macroscopic and microscopic studies

Abstract

Macroscopic crystallization kinetics was investigated using differential scanning calorimetry (DSC). Non-isothermal crystallization of poly(trimethylene terephthalate) (PTT) was considered in this study. The kinetics of crystallization process was evaluated by the macrokinetic models, namely Avrami, Tobin, Ozawa, Ziabicki. The effective energy barrier was determined by the differential isoconvesional method of Friedman. For the crystallization from the melt state, the evaluated crystallization rate was found to increase as the cooling rate increased. In case of the crystallization from the glassy state, the evaluated crystallization rate was found to increase as eating rate increased. Moreover, the miscibility, melting, crystallization kinetics behavior, and morphologies of PTT/PEN blends were also studied. A single composition-dependent glass transition temperature (Tg)was observed in these blends system, implying that these blends are fully miscible in the amorphous phase. The subsequent melting endotherms after melt-crystallization exhibited the melting point depression behavior in which the observed meliting temperatures decreased with an increasing amount of mionor component of the blends. Isothermal melt-crystallizationk kinetics was considered both macroscopically (using DSC) and microscopically (using polarized light microscopy (PLM)). The overall crystallization and spherulitic growth rates were found to increase with increasing crystallization temperature Tc. Considering at the same undercooling, the overall rates were found to increase with increasing PEN contents while the growth rates in blends were unaffected by composition. The morphologies of blends depend on both Tc and composition.