Optimisation of anionic polyamide-6 for vacuum infusion of thermoplastic composites: choice of activator and initiator

A process for the manufacturing of large thermoplastic composite structures through vacuum infusion is currently being developed at Delft University of Technology. This article discusses the choice of activator, initiator and polymerisation temperature for reactive processing of the anionic polyamide-6 resin. It will be shown that this manufacturing process requires another activator–initiator combination than conventional casting. The concentration of the reactive species and the polymerisation temperature, however, determine the polymerisation rate and the physical properties of the polymer. For use in a vacuum infusion process, a hexamethylene-1,6-dicarbamoylcaprolactam activator and a caprolactam magnesium bromide initiator are suggested to allow for longer infusion times and to increase the compatibility with reinforcing fibres.