The crystallization dynamics of Nylon 66/Nylon 48 blends, the crystalline/crystalline polymer blend, was analyzed by differential scanning calorimetry (DSC) under isothermal conditions. The equilibrium melting temperature (T-m(0)), crystal growth rate (G) and the nucleation rate (N) depended on both the degree of supercooling (DeltaT) and the blend fraction (phi). The DeltaT/T-m(0) values obtained at the fixed G, which corresponded to the chemical potential different between molecules in the liquid and the crystal states, and the surface free energy parameters evaluated from G and N depended on phi for blends. The results suggested that Nylon 661Nylon 48 blends are miscible in all blend fractions. The result agrees with the intermolecular interaction parameter (chi) obtained from T-m(0) depression. Infrared spectroscopic and X-ray diffraction data indicated that the hydrogen bond became weak and the crystalline structure became disordered one by blending. (C) 2003 Elsevier B.V. All rights reserved.