Multi-die thermoplastic pultrusion of carbon reinforced PolyEtherKetoneKetone bars at 1 m/min using preimpregnated tape

This study aimed at achieving multi-die thermoplastic pultrusion at 1 m/min for advanced air mobility applications. PolyEtherKetoneKetone impregnated carbon fibre (C/PEKK) prepreg tape was used. The measured void content of the as-received tapes was 15.6 vol%. A finite element simulation was developed to determine the temperature profile of the pultrudate for different die temperature set points. Three pultrusion speeds were tested: 50, 500, and 1000 mm/min. The die temperatures were adjusted using the simulation to ensure reaching the processing temperature of 370 °C in the compaction dies regardless of the pultrusion speed. The measured void content of the pultrudates increased from 1.8 vol% to 2.8 vol% for the lowest to highest pultrusion speed. The final pultruded parts do not exhibit deconsolidation, as indicated by the consistent thickness values obtained across all experiments. It was observed that improving the surface finish required relocating the cooling die further downstream from the last heated die. The surface finish (Ra) at 500 mm/min was 3.11 μm, whereas the values obtained at 50 and 1000 mm/min were comparable. A flexural test in accordance with ASTM D790 did not show any significant variation with increasing pulling speed. The flexural strength ranged from 998 to 1041 MPa, while the flexural modulus remained between 106 and 109 GPa.