Study On Preparation And Properties Of High Performance Polyimide Fiber Reinforced Epoxy Resin Composites

High performance fiber reinforced resin matrix composites have important roles in many fields including aerospace as well as national economy.High performance polyimide(PI)fiber is a new type of organic fibers with high strength,high modulus,high toughness,radiation resistance,high temperature resistance,high insulation and good dielectric properties.It is the most comprehensive high performance organic fibers and it is suitable for using as reinforcement.PI/EP composites with PI fiber as reinforcement and epoxy resin as matrix can reduce the weight of structures and possess high insulation properties.It is of great significance to promote the application and development of new types of composite materials that the basic research of PI/EP composites.In this paper,PI/EP and aramid/EP composites were prepared by wet winding combined with autoclave molding technology.The research contents are as follows:1.Properties of epoxy resin matrix.(1)The curing process and curing kinetics parameters of DGEBA and TDE-85 resin and aromatic amine DEDDM were studied by non-isothermal DSC method.Nano-silica particles were used to modify epoxy resin,and the dielectric properties were characterized.The SEM morphology of the cured section was observed,and the effects of the change of silica content on the mechanical properties of the resin was analyzed.The results show that the tensile properties and impact strength of TDE-85 resin modified by 4wt.%Si02 are the highest,and the dielectric loss value of TDE-85 resin modified by Si02 has small to increase.(2)DGEBA/D-400 resin was toughened by liquid rubber particles(CTBN and HTBN).The influence of rubber type and contents on mechanical properties was discussed.The results show that CTBN can greatly improve the impact strength of cured resin2.Preparation and properties of PI/EP(DEDDM)composites.Prepreg was prepared by wet winding and composite laminates were prepared by autoclave molding.Firstly,the effects of molding processing on the properties of prepreg and composite laminates were analyzed.Then,the basic mechanical properties of the composites were tested,and the failure modes of the composites were analyzed based on the failure morphology of macro and micro specimens.The dielectric properties,insulation properties and heat resistance of the composites were characterized.The results show that the mechanical properties of PI/EP composites are excellent,the interlaminar shear strength can reach to 70 MPa,the tensile strength is 1635 MPa and the compressive strength is 298 MPa,the longitudinal tensile failure mode of PI/EP composites is explosion damage of filament,and the longitudinal compressive failure mode is 450 kinking band.3.PI/EP(D-400)toughness composite laminates were prepared by the same molding processing,and basic mechanical properties,impact properties and failure modes of composites were analyzed.The results show that the basic mechanical properties of PI/EP(D-400)toughness composites are lower than those of PI/DEDDM composites,but impact resistance is excellent.In particular,the external and internal damage area of CTBN toughened composite laminates are small,and the peak impact load of laminates is close to 7KN.