The effect of nucleating agents on the polymorphic crystallization behavior of poly(butylene adipate) (PBA) was studied with four kinds of commercially available nucleating agents, such as talc and boron nitride. The crystal structures of the a and beta forms were studied with wide-angle X-ray diffraction. The beta-to-alpha-crystal transformation of PBA in the absence and presence of the nucleating agents in isothermal crystallization and nonisothermal crystallization processes was studied with differential scanning calorimetry and polarized optical microscopy. In both isothermal and nonisothermal crystallization, the introduction of nucleating agents selectively initiated the nucleation of the a-form crystal, which was relatively slow in the absence of nucleating agents. The nucleating activity of the four kinds of nucleating agents in the crystallization of the PBA a-form crystal was determined by the study of the nonisothermal crystallization, spherulite morphology, and isothermal kinetics. (c) 2005 Wiley Periodicals, Inc.