Effect of Melting Conditions on Crystallization Behavior of Poly(trimethylene terephthalate)

The effect of melting conditions on the crystallization kinetics of poly(trimethylene terephthalate)(PTT) was presented by means of depolarized light intensity (DLI) technique. The kinetics of PTT crystallization from melt depends on melting conditions and primarily upon the temperature of the melt. Higher melt temperature or longer time of melting may cause a reduction of crystallization rates at the melt temperature range from 506 to 531 K. Crystallization mechanism of PTT crystallizing from various melting conditions has been discussed according to Avrami kinetics parameters and morphology study. The reduction of the rate may result from two reasons: 1) the decrease of regularity such as residual nuclei in the PTT melt which lead to a reduction in the number of heterogeneous nuclei in the crystallization process; 2) the decreased spherulitic growth rate of PTT with higher melt temperature or longer residence time for melting