Crystallization kinetics of poly (butylene terephthalate) (non-talc-PBT) and its 0.1 wt % talc composites (talc-PBT) was determined for a wide range of cooling rates and isothermal temperatures. The critical cooling rate to suppress crystallization is 2000 K s 21 for non-talc-PBT and 7000 K s 21 for talc-PBT. The cooling rate dependence of the total enthalpy change and heating rate dependence of enthalpy of cold crystallization are quantitatively discussed on the basis of the Ozawa's method. For isothermal crystallization, the annealing-temperature (T iso ) dependence of crystallization half-time (t 1/2 ) shows a bimodal curve with two minima. Talc shortens the t 1/2 at T iso above 340 K and acts as a heterogeneous nucleation agent. Tammann's approach revealed that the t 1/2 is shortened by pre-nucleation for non-talc-PBT but not for talc-PBT.

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