Optimisation of anionic polyamide-6 for vacuum infusion of thermoplastic composites: Influence of polymerisation temperature on matrix properties

A process for the manufacturing of large thermoplastic composite structures through vacuum infusion is currently being developed at the Delft University of Technology. Here, we will discuss the effect of the polymerisation temperature on the properties of an anionic polyamide-6 specifically formulated for vacuum infusion. In general, an increase in polymerisation temperature results in a higher polymerisation rate, a higher degree of branching and a lower degree of crystallinity. The resulting effect on final conversion, molecular weight, melting point and mechanical properties is discussed. Finally, the influence of the polymerisation temperature on the shrinkage is considered. It will be shown that a too high shrinkage rate decreases the conversion and generates voids, which both have a detrimental effect on the mechanical performance of the polymer.