The activated anionic ring opening polymerization of ε-caprolactam to polyamide 6 is highly sensitive to external influences such as water. Based on an initial theory, preliminary reaction kinetic tests are carried out with the aim of compensating the influence of the water by increasing the activator and catalyst concentration. Different formulations of activator and catalyst were studied to understand the influence of water on the concentration of activator and catalyst. It was found that the compensation of added water with activator and catalyst restores the original reaction time. The test plates produced are examined with regard to their mechanical characteristics and the polymer properties. The results of the mechanical characterization show no significant impairment after compensation of the added water. The physical properties of the matrix show degradation with repeated compensation. However, the residual ε-caprolactam content remains below the critical value of 1% for three of the four investigated formulations.

The reaction kinetics of anionic polymerization for the production of anionic polyamide 6 (aPA6) are widely understood. It is also known that this reaction is very sensitive to external influences such as water. This paper analyzes and quantifies the influence of water on the reaction of ε-caprolactam to anionic polyamide 6. A kinetic model is developed in which the reactive molecules of the activator and catalyst are defined as variables and the concentrations of activator and catalyst as well as water content are considered. A model for the calculation of the reaction kinetics is established and validated with experimental data. The developed model can be used to predict the influence and compensation of water by addition of surplus activator and catalyst during the polymerization of ε-caprolactam.