Improving thermal stability and mechanical properties of high temperature carbon fibre phthalonitrile resin composites via Nano-CuO modified matrices

High performance phthalonitrile (PN) resins and their carbon fibre reinforced composites have been developed to meet harsh and stringent application scenarios in aerospace, aircraft, naval industries due to the highly crosslinked network, abundant polyaromatic structure and superior thermal stability and mechanical properties of PN resins. In this study, the thermal stability and mechanical properties of carbon fibre-reinforced PN matrix composites were improved by introducing CuO nanoparticles (NPs). These NPs promote the formation of phthalocyanine rings during PN resin curing, significantly improving the curing efficiency, thermal stability, and wettability of the resins, especially when the surfaces of CuO NPs were treated with silane (mCuO NPs). Incorporating CuO NPs into the PN matrix significantly increased both flexural strength and modulus. For the carbon fibre reinforced PN matrix composites, incorporating 10 wt% mCuO NPs, the flexural strength increased 128 % from 188 MPa to 429 MPa, and the flexural strength retention rate enhanced from 41 % to 60 %, compared with the carbon fibre reinforced neat PN resin composites, after thermal exposure at a heat flux density of 90 kW/m² (i.e., coil temperature of 930 °C in the cone calorimeter). The drastically enhanced thermostability and residual mechanical strength in carbon fibre PN resin composites provide high potential opportunities for preparing lightweight thermal protective aerospace and marine structures.