Melting behaviors and nonisothermal crystallization of poly(butylene terephthalate)/poly(ethylene-co-glycidyl methacrylate) (PBT/PEGMA), PBT/commercial modified montmorillonite clays (PBT/Clay), and PBT/exfoliated silicates (PBT/PEGMA/Clay) nanocomposites were studied by wide-angle X-ray diffraction and differential scanning calorimeter. PEGMA is used as a compatibilizer. For both isothermally and nonisothermally crystallized samples, PEGMA facilitates the recrystallization of PBT during the heating scans, and leads to a less degree of perfection of the crystals. However, the clay hinders the recrystallization growth during heating scans, and increases perfection of the crystals. Nonisothermal crystallization kinetics was described by kinetic models and undercooling was taken into account. The PEGMA would lead to an increase of the blend viscosity, rendering the chains less mobile and lower the crystallizability of PBT in PBT/PEGMA. The well-dispersed exfoliated silicates in PBT/PEGMA/Clay cause a large number of nuclei to precede crystallization. The fold surface free energy (sigma(e)) and activation energy also supported the interpretation. (c) 2008 Wiley Periodicals, Inc.