Effect of fabric architecture, compaction and permeability on through thickness thermoplastic melt impregnation

To reduce the cycle time of structural, automotive thermoplastic composites, we investigated the potential of direct thermoplastic melt impregnation of glass fabrics using an injection moulding process. At the high pressures that occur during the process, the effect of the fabric architecture on the impregnation, compaction, volume fraction and permeability of two unidirectional fabrics was studied. Using impregnation experiments with a low viscosity PA6 melt, we identified a favourable processing window resulting in an impregnation time of 5 min. The impregnation experiments with thermoplastic melts demonstrate that textile architectures promoting dual scale flow during impregnation are favourable for complete filling. Based on our findings, thermoplastic compression resin transfer moulding is an efficient processing route for automated production of composite parts with a high fibre volume fraction, if the fabric architecture is adapted for higher processing pressures and by fully utilising dual scale flow.