Study On Mechanical Properties Of Carbon Fiber Reinforced Polyimide Composites

Submersible is an important equipment for the exploitation of Marine resources in deepsea equipment.As one of the most important components of submersible,the performance of pressure hull is affected by many factors,among which material properties are the prerequisite for optimizing the overall performance.Compared with traditional metal materials,composite materials have superior properties that no single material can have.Nonmetallic composite materials are widely used because of their advantages of light weight and high strength.The selection of substrate in non-metallic composite materials is crucial,among which,we choose the thermosetting material of polyimide as the substrate,in order to expand the application range of polyimide materials,so that its potential application in pressure shells,it is necessary to improve the mechanical properties of polyimide materials through some methods.In the current field of composite reinforcement,the most widely used and excellent performance is carbon fiber reinforced composite.Therefore,this paper chooses carbon fiber cloth to improve the performance of polyimide materials.Carbon fiber belongs to inorganic substance,matrix resin belongs to organic matter,and the effective combination between inorganic substance and organic matter must change the properties of both.In order to solve this problem,this paper carried out different surface treatments on carbon fiber cloth,and prepared carbon fiber reinforced polyimine composite material.The effects of different carbon fiber modification methods on mechanical and thermal properties of the composite were investigated.Based on the results of interlayer shear test of carbon fiber reinforced polyimine composite,the stress and strain analysis of the whole and interface of the composite was carried out by ABAQUS finite element software.Firstly,according to the molar ratio of p-phenyldiformaldehyde,diethylenetriamine and tri(2-aminoethyl)amine,which is 3:0.9:1.4,a kind of polyimine film material was prepared by the decomposition reaction.Carbon fiber cloth was modified by different surface modification methods,and carbon fiber reinforced polyimide composite was prepared by hot pressing method.Secondly,the structure and properties of polyimine materials were characterized by Fourier infrared spectroscopy(FTIR),thermogravimetric analyzer(TGA),X-ray diffractometer(XRD)and X-ray photoelectron spectroscopy(XPS).The impact properties,bending properties and interlayer shear properties of the composites were tested,and the fracture surface of the composites was photographed by scanning electron microscopy to analyze its fracture mechanism.The functional groups inside and on the surface of the composite were characterized by infrared spectroscopy.The element composition of the composite was detected by X-ray photoelectron spectrometer.X-ray diffractometer is used to determine whether the corresponding phase is present in the synthetic material.The results show that:(1)polyimide materials with good properties can be effectively synthesized through the decomposition reaction of imide complexes between aldehydes and amines,and this is also proved by infrared test,XPS test and XRD test.The mass change of polyimine substrate with temperature was measured by thermogravimetric analyzer.(2)Through unique technical means,this paper successfully modified the surface of carbon fiber cloth in three ways,so as to prepare a polyimine resin matrix composite material with good toughness and corrosion resistance.(3)The composition and microstructure of the samples were studied by infrared spectroscopy,scanning electron microscope,X-ray photoelectron spectrometer and X-ray diffractometer.Through impact test,bending test and interlayer shear test,the mechanical properties of the prepared samples were analyzed and explored,and the strengthening effects of three modification methods were discussed.It was concluded that Na OH and silane coupling agent had the best effect.Finally,ABAQUS finite element simulation analysis software was used to simulate and analyze the interlaminar shear test of carbon fiber composite laminates by using cohesion unit,and the simulation results were compared with the shear test results.The force and displacement curves of the two models are highly consistent with each other,as well as their positions and failure forms.The error between the simulated strength results and the experimental results is within an acceptable range,indicating that the simulation model has a reference importance in predicting the interlaminar shear failure.