Unidirectional carbon fibre reinforced polyetherimide: Pilot-scale wet powder impregnation and critical composite properties

High-performance thermoplastic composites are increasingly favoured over traditional thermosets due to their superior toughness, faster processing without complex curing processes, lower health risks, and potential recyclability. Among thermoplastics, amorphous polyetherimide (PEI) offers an attractive set of thermal and mechanical properties compared to semi-crystalline alternatives such as poly(ether-ether-ketone) but at a lower cost. Besides thermal and physical characteristics of PEI, single fibre model composite properties, we present a pilot-scale wet powder impregnation route for manufacturing unidirectional (UD) carbon fibre-reinforced PEI composite tapes with a fibre volume fraction of 58%, tensile load of 1462 ± 72 N and modulus 109 ± 2.3 GPa. The consolidated laminates had a density of 1.56 g/cm 3 and a void content of 1.6%. UD CF/PEI composites had a short beam shear strength of 74 ± 8 MPa and a compressive strength and modulus of 623 ± 3 MPa and 107 ± 8 MPa, respectively, at room temperature. These properties decreased with increasing temperature to 150°C due to matrix softening. Mode II fracture toughness approached the lower bound of CF/PEEK composites making PEI a promising candidate as a matrix for high-performance composite applications.