Crystallinity in poly‐N‐methyllaurolactam and copolymers

Fully methylated nylon 12 was prepared by the hydrolytic polymerization of N‐methyllaurolactam. The polymer, with about 20% crystallinity, has a crystal structure different from that of nylon 12. The X‐ray diffraction patterns of copolymers of N‐methyllaurolactam and laurolactam were shown to be composition‐dependent. Copolymers containing up to 15% laurolactam units exhibited a crystal structure essentially the same as poly‐N‐methyllaurolactam. Copolymers containing from 20 to 50% laurolactam are transition structures, whereas copolymers containing more than 50% laurolactam units exhibit a crystal structure characteristic of polylaurolactam. DSC data on the homopolymers and copolymers are also reported.