Anionic copolymers of caprolactam with laurolactam (nylon 6/12 copolymers)—I. Preparation and general properties

Copolyamides of high mol.wt were obtained by the anionic copolymerisation of ?-caprolactam with ω-laurolactam at 180°C, using a sodium caprolactamate-N-phenylcarbamoylcaprolactam initiator activator system. The proportions of co-units in the copolymers were close to those in the comonomer feeds. The copolymers were crystalline and substantially fully hydrogen-bonded over the whole range of compositions, except at 50/50 mole% ratio, each displayed only one crystalline phase corresponding to that of the major component. T_m and density measurements indicated a crystallinity minimum at 50 60 mole% NH(CH₂)₅CO unit content. The properties of the copolyamides were consistent with random copolymeric structures.