Moisture sorption of ɛ-caprolactam and its influence on the anionic polymerization in the thermoplastic RTM-process - An overview

Thermoplastic fibre reinforced composites (FRPs) offer, in comparison to duromeric composites, a range of advantages. Higher impact strength, simple functionality and good recyclability are the main features of these composite parts. Thermoplastic resin transfer moulding (T-RTM) is an already extensively investigated manufacturing method for such components. As matrix components "-caprolactam is used in combination with activator and catalyst. The anionic ringopening polymerization (aROP) is sensitive to external influences such as water. The chemical reactions of the matrix components with water are examined in detail and explained according to their probability of occurrence. Since water absorption in the process cannot be excluded when materials are processed in series production, the sorption behaviour of the materials is very important. This has not yet been characterized in detail, which is why this paper considers the basics of sorption measurement of the materials used in the T-RTM process, and discusses suitable measurement methods. Finally, a calculation of the deactivated amounts of activator and catalyst in relation to the reaction rate serves as a basis for further experiments of cycle time optimization in the T-RTM process.