Crystallization behaviour of poly(N-methyldodecano-12-lactam) Part 1. Isothermal crystallization

Differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS) and Raman spectroscopy have revealed a complex melting/crystallization beh aviour of poly(N-methyldodecano-12-lactam), MPA. After cooling from the mel t to crystallization temperature T-c of 250-280 K, primary lamellar structu re is formed which melts at about 324 K. During later stages of isothermal crystallization, imperfect "fringed" crystallites melting at about T-c + 10 K are formed in the interlamellar space of the primary structure. On heati ng, additional crystallization of the primary lamellae takes place with an optimum temperature at about 300 K. In the case of isothermal crystallizati on at T-c = 290 K and higher, the two steps of the primary structure format ion combine in a single isothermal step. Under certain conditions an additi onal endotherm, possibly corresponding to some less-defected "fringed" lame llae, was detected. On further heating, the primary crystallites undergo re crystallization with an optimum temperature at about 327 K. The final highe r-ordered structure melts at about 335 K. Melting temperature of the imperf ect crystallites shows a strong dependence while that of the highest-meltin g structure a negligible dependence on T-c. Within 24 h at 300 K, the MPA s ample reaches crystallinity of about 34%. (C) 2000 Elsevier Science Ltd. Al l rights reserved.