The nonisothermal crystallization of poly (butylene dodecanedioate) was studied by differential scanning calorimetry

crystals of polyesters were observed through polarized optical microscope

and an Avrami method was used to analyze the kinetics of nonisothermal crystallization The results showed that the crystallization temperature decreased slowly with an increase in the cooling rate．Furthermore

secondary nucleation was observed in the pmcess of PBDD nonisothermal crystallization

and the Avrami exponential values n of PBDD indicated that the mechanism of crystallization was a tridimensional growth with heterogeneous and homogeneous nucleation Meanwhile

the Avraml values n of P(BDD-co-BT)-20 is 1．which indicated that their mechanism of crystallization was a one-dimensional growth with heterogencous nucleation Crystallization activation energies implied that it is easier to crystallize for copolyester From the observed results of spherulites

it can be concluded that the size of sphemlites decreases with increasing the content of terephthalic acid.