Alternating-layered spherulites in thin-film poly(trimethylene terephthalate) by stepwise crystallization schemes

Structuring of multi-layered spherulites in aryl polyester of poly(trimethylene terephthalate) (PTT) by stepwise crystallization was attempted. Characterization of feasibility was performed by polarized-light microscopy (POM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). Two- or three-layered spherulites could be developed in PTT by subjecting to stepwise crystallization. Sequence and number of layers in spherulites can be designed by altering the steps of temperatures with proper holding time. Time must be allocated properly in the multiple steps if three different textures are to be structured into one single PTT spherulite by stepwise crystallization. Coexistence of multiple lamellar thicknesses and various degrees of crystal perfection were supported by DSC results. The various crystalline regions of the layered spherulites in PTT develop upon stepwise crystallization exhibit the same unit cell as demonstrated by WAXD crystallographs.