Crystallization of random copolymers based on poly(hexamethylene adipamide)

The effects of crystallization temperature and time for a series of polyamide 66 copolymers have been studied. Measurements were made of the growth rate of spherulites, the melting temperature, and the lamellar thickness. The lamellar thickness was found to be approximately constant at 1 ½ to 2 chemical repeat units. The growth rate is enhanced for the nylon 6T copolymers and reduced for the nylon 6I and nylon 6 copolymers. Although the polymers show typical T_c vs. T_m behavior on a Hoffman- Weeks plot, the Gibbs-Thompson plot indicates that there are only small changes in the lamellar thickness with increasing melting point. Based on calculations of the size of the critical nucleus, the Secondary Nucleation Model does not apply for polyamide 66. The crystallization dynamics are dominated by hydrogen bonding.