Miscibility of Nylon 66 and Nylon 48 blend evaluated by crystallization dynamics

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 (Tm0), crystal growth rate (G) and the nucleation rate (N) depended on both the degree of supercooling (ΔT) and the blend fraction (φ). The ΔT/Tm0 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 φ for blends. The results suggested that Nylon 66/Nylon 48 blends are miscible in all blend fractions. The result agrees with the intermolecular interaction parameter (χ) obtained from Tm0 depression. Infrared spectroscopic and X-ray diffraction data indicated that the hydrogen bond became weak and the crystalline structure became disordered one by blending.