X-ray diffraction method and differential scanning calorimetry analysis have been used to investigate the nonisothermal crystallization of poly(3-hydroxybutyrate) (PHB)/poly(ethylene glycol) phosphonates (PEOPAs)-modified layered double hydroxide (PMLDH) nanocomposites. Effects of cooling rates and PMLDH contents on the nonisothermal crystallization behavior of PHB were explored. These results show that the addition of 2 wt % PMLDH into PHB caused heterogeneous nucleation increasing the crystallization rate and reducing the activation energy. By adding PMLDH into the PHB probably hinder the transport ability of the molecule chains and result in a decreasing crystallity of PHB, thus increasing the activation energy. The correlation among melting behavior, apparent crystallite size, and paracrystalline distortion of PHB/PMLDH nanocomposites has been also discussed. (c) 2007 Wiley Periodicals, Inc.