Study On The Toughening Modification Of Basalt Fiber Reinforced Phthalonitrile Resin Composites

Phthalonitrile resin has excellent heat resistance,mechanical properties,weather resistance and dimensional stability,etc.Therefore,as a composite matrix resin,it is widely used in aerospace,high temperature industry and other fields.However,the cured product of phthalonitrile resin has the characteristics of poor impact-resistance due to the high crosslinking density.In addition,the high viscosity during molding and processing limits further development and application.How to improve the toughness of phthalonitrile resin based on its original performance has become an urgent problem to be solved.This thesis uses high-performance thermoplastic resins(PPEN and PPENK)to toughen modified phthalonitrile resin(BPh),and prepares basalt fiber-reinforced blended resin system composites,and explores PPEN and PPENK influence on the comprehensive properties of BF/BPh composites.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 to107.7 KJ/m~2,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 ther-moplastic PPEN and PPENK can significantly inhibit the delamination between the layers and the fiber pullout and debonding.Amino-terminated PPENK(PPENK-DA)with different molecular weights was designed and synthesized for toughening modified BF/BPh composites.The curing behavior of the BPh/PPENK-DA blends have been characterized by DSC and Rheometer.The thermal stability of the cured resin system has been studied in detail.The influence of the molecular weight of PPENK-DA on the mechanical properties of BF/BPh/PPENK-DA composites has been investigated.The results show that as the molecular weight of PPENK-DA is 8000,the bending strength of BF/BPh/PPENK-DA laminate can reach 740 MPa.And when the molecular weight of PPENK-DA is 10000,the impact strength can reach 116.3 KJ/m~2.The DMA test shows that the material maintains excellent thermal stability.At the same time,the SEM of the fracture surface of the composite laminate shows that the resin matrix and the basalt fiber have good interfacial adhesion.