Improved mechanical properties of basalt fiber/phthalonitrile composites modified by thermoplastic Poly(phthalazinone ether nitrile)s

Phthalonitrile resin is a potential high-performance composite matrix, its brittleness and weak interaction with fiber are the main obstacles to its wide application. High-performance thermoplastic poly(phthalazinone ether nitrile)s (PPEN) and poly(phthalazinone ether nitrile ketone)s (PPENK) have been used to toughen basalt fiber (BF) reinforced 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPh) composite. The curing kinetics for the BPh/PPEN and BPh/PPENK blends have been investigated using DSC. The structures and thermal properties of the cured BPh blends have been studied in detail. The effects of PPEN and PPENK on the mechanical properties of the modified BF/BPh composite have been assessed. The non-notched impact strength of BF/BPh/PPENK laminate can be up to 107.7 kJ/m2, which is 64.2% higher than that of the BF/BPh laminate. And the interlaminar shear strength of BF/BPh/PPEN laminate can reach 42.5 MPa, 134.8% higher than that of the BF/BPh laminate. Simultaneously, the fracture surface of the laminate showed that the thermoplastic PPEN and PPENK can significantly inhibit the delamination between the layers and the fiber pullout and debonding.