Kinetics of the anionic polymerization of ε‐caprolactam from an isocyanate bearing polystyrene

Abstract This work aims to systematically study a reactive extrusion process for the synthesis of graft copolymers with polystyrene (PS) as backbone and polyamide 6 (PA6) as grafts. The underlying chemistry relies on the use of a random copolymer of styrene (St) and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI), PS‐ co ‐TMI, to activate the polymerization of ε‐caprolactam (CL) using sodium ε‐caprolactam (NaCL) as a catalyst. To obtain sufficiently high polymerization rate and monomer conversion, the following conditions should be met simultaneously: polymerization temperature higher than 220°C, TMI content in PS‐ co ‐TMI higher than 2 wt%, and the molar ratio between the isocyanate group in PS‐ co ‐TMI and NaCL smaller than 3. Moreover, feeding mode has a little effect on the CL conversion and the composition of PS‐ g ‐PA6 but has a strong effect on the polymerization induction time. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers