Crystallization kinetics of poly(trimethylene terephthalate)

The bulk isothermal crystallization kinetics of poly(trimethylene terephthalate) (PTT) was studied using a differential scanning calorimeter. Avrami's theory was used to analyze the data. Based on crystallinity growth rate, Avrami rate constant, K, and crystallization half-time, PTT's crystallization rate is between those of poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) when compared at the same degree of undercooling. PET has the highest crystallization rate with K in the order of 10(-2) to 10(-1) min(-n). It is about an order of magnitude faster than PTT at 10(-3) to 10(-2) min(-n), which in turn is an order of magnitude faster than PET with K of 10(-4) to 10(-2) min(-n). Contrary to previous reports (PTT was not included in the study) that aromatic polyesters with odd numbers of methylene units were more difficult to crystallize than the even-numbered polyesters, PIT did not fit in the prediction and did not follow the odd-even effect.