Preparation And Properties Analysis Of Carbon Fiber Reinforced Composites

The carbon fiber reinforced polymer composites rods have light quality, good corrosion resistance,high specific stiffness, high specific strength, simple construction and excellent mechanical properties in comparison with steel rods.It has been more and more widely used in bridge construction, civil engineering and other fields.This paper is based on making the carbon fiber reinforced epoxy resin composite rods. The key control parameters of continuous resin transfer molding process were obtained through the systematically study of curing reaction of epoxy resin systems. In order to verify the feasibility of the CRTM process, the unidirectional carbon composites rods were prepared. On the foundation of this prepareration, it not only established the continuous braiding-resin molding process method but designed and prepared the braided composite rods, which has a diameter of 5 mm and braiding angle 30°,40 ° and 50°, respectively. Carbon fiber reinforced composite rods were tested by three point bending, compression, shear and torsion test, which researched experimental temperature, molding process and braiding angle on the influence of composite rods. The conclusions are as follows:(1) Viscosity-temperature test and DSC test was carried out on the selection of CP-02A/B epoxy resin, it is found that the injecting temperature of epoxy resin is 55℃～60℃,the gel temperature is 98.9℃,the curing temperature is 121.3℃ and the post-processing temperature is 134℃ from the experimential data. The three zone temperature of the die was set on the basis of above analysis.Through the process validation of the early stage in this experiment, the finial CRTM molding process parameters were as follows:three zone temperature of the die is followed by 130℃, 160℃,180℃; injecting temperature of resin is 55 ℃, injecting pressure is 0.2 MPa and pultrusion speed is 0.3 m/min.(2) In the comparsion experiments, three temperature points:25℃,70℃,180℃ were chosen based on the Tg=183℃ of resin matrix. The results show that with increasing experimential temperature, the bending strength and compressive strength of unidirectional carbon fiber composite rods have all decline. This may be related to carbon fibre and epoxy resin have different thermal expansion coefficient such that elevated temperatures makes the combining between carbon fibre and resin matrix variation.(3) When the fiber volume content and sample diameter are certain, the bending strength and torsional strength of the unidirectional carbon fiber composite rods prepared by conventional pultrusion process compared with those prepared by CRTM molding process increase by 11.11% and 8.18%, separately, shear strength and compressive strength reduced 1.59% and 1.72%,respectively.However, the coefficient of variation of the samples prepared by the CRTM process significantly reduce. From what has been discussed above, the use of CRTM molding process can effectively reduce the discrete of experimental data, which greatly improves the stability of the test results.(4) The braiding angle plays a major impact on the mechanical of braided composites rods. The bending strength of braided composite rods decrease, the compressive strength increases first and then decreases, shear strength and torsional strength increases with the increase of braiding angle.