Optimization of initiator and activator for reactive thermoplastic pultrusion

In order to manufacture continuous fiber reinforced thermoplastic composites with high fiber content, reactive thermoplastic pultrusion was developed by using the anionic polymerization of polyamide-6 in this study. Firstly, based on the polymerization time tests, combination of activator of difunctional hexamethylene-1,6-di carbamoylcaprolactam (C20) and initiator of sodium caprolactamate (C10) were chosen as the most suitable formula combination for pultrusion. Effects of concentrations of the activator C20 and the initiator C10 on the polymerization time, molecular weight of polymer and degree of conversion were also investigated. Then, the range of initial polymerization temperature was determined, which had a great influence on the impregnation of dense fiber reinforcement. Comparing with commercial polyamide-6, the anionic polyamide-6 has a higher modulus and lower elongation. Finally, continuous glass fiber reinforced polyamide-6 composites with 50% volume fraction were successfully pultruded. Great interfacial adhesion between fiber and polymer was observed by the scanning electron microscope.