Designing phthalonitrile/hydroxyl compound systems for high performance CFRP composites

High mechanical residues at/after elevated temperatures are basic prerequisites for the engineering applications of carbon fiber reinforced polymer (CFRP) composites in special fields like aerospace. In this study, phthalonitrile (PNP) copolymers based on hydroxyl compounds of BP monomer, PEP and BZCN resin were designed and their curing behavior and processability were investigated for realizing the corresponding CFRP composites. High temperature mechanical performances of PNP/hydroxyl compound/CF composites under instantaneous and non-instantaneous states are systematically assessed. At 300 °C, PNP/hydroxyl compounds/CF composite showed a retention rate of tensile, compressive, flexural strength and flexural modulus higher than 35%, 95%, 80% and 90%, respectively. After 300 °C/50 h thermal aging, their flexural properties show no obvious attenuation. Even after being aged at 350 °C for 50 h, the residue of flexural modulus is above 90% while that of flexural strength is over 60%. The mass residue of PNP/hydroxyl compounds/CF composites were all higher than 98% and 90% after aging at 300 °C and 350 °C for 50 h. PNP/hydroxyl compounds/CF composites, with the excellent comprehensive mechanical properties, can be used as high performance engineering materials. (paper)