Isothermal Crystallizaiton Kinetic and Melting Behaviors of Nylon 6/66/510

In this work, nylon 6/66 (S0) and nylon 6/66/510 (S1~S3) containing 5 ~ 15 mol % nylon-510 were synthesized by melt condensation polymerization and the isothermal crystallization kinetics and melting behaviors after isothermal crystallization of copolymer were systematically studied by differential scanning calorimetry (DSC). The chemical structures and molecular weights were characterized by means of nuclear magnetic resonance (1H-NMR). The values of t1/2 and the equilibrium melting temperature for all samples were calculated by Avrami equation and Hoffman-Weeks, respectively. The crystal structure of the copolyamides were also investigated by wide-angle X-ray diffraction (WARD). The results shows that: (1) Avrami model can be used to well describe the isothermal crystallization behavior of the copolyamides, and all the values of t1/2 increase with increasing the Tc or the mole fraction of nylon 510. (2) The crystallization activation energy (ΔE) and nucleation constant (Kg) both increase with increasing the mole fraction of nylon-510, which indicating that the addition of nylon nylon-510 decreases the crystallization rate of copolymer.