Mechanical Properties Of Epoxy Resin And CFRP Composite Enhanced By Gelatin Functionalized Carbon Nanomaterial

Carbon fiber reinforced polymer(CFRP)is widely used in aerospace and other fields due to its excellent properties such as high specific stiffness,high specific strength,and strong corrosion resistance.The interfacial mechanical property of carbon fiber-resin matrix and the mechanical properties of resin matrix are the key factors for the performance of CFRP.However,due to the poor interfacial mechanical property between carbon fiber and resin and the low mechanical property of resin,it is difficult to satisfy the application requirement of high performance of CFRP.A protein gelatin was proposed as a surfactant in the thesis to improve the dispersibility of gelatin functionalized carbon nanofibers(g-CNFs)in epoxy resin and the mechanical property of epoxy nanocomposite enhanced by g-CNFs(gCNFs/epoxy).Fiber surface modification method based on gelatin functionalized carbon nanotubes(g-CNTs)was used to improve the interfacial mechanical property of carbon fiberresin,and then improve the mechanical property of CFRP composite enhanced by g-CNTs(g-CNTs-CFRP).The numerical analysis method of mechanical property of epoxy nanocomposite enhanced by g-CNTs(g-CNTs-EP)was improved,and the tensile mechanical property was successfully predicted.The main work and results are as follows:Optical microscopy and scanning electron microscopy characterization reveals that gelatin functionalization improves the dispersion property of g-CNFs in epoxy resin.The flexural mechanical property and dynamic mechanical property of g-CNFs/epoxy were analyzed.With the nanofiller concentration of 0.25 wt%,the flexural strength and modulus of g-CNFs/epoxy are 118.97 MPa and 3.62 GPa,which are 29.1% and 27.1% higher than those of pure epoxy resin,respectively.The glass transition temperature of g-CNFs/epoxy is about 53.02 ℃ and 12.7% higher than that of pure epoxy resin.According to the fracture characteristics of g-CNFs/epoxy,the reinforcement mechanism of g-CNFs enhancing the mechanical property of epoxy resin is revealed.The g-CNTs-CFRP composite was prepared by the fiber surface modification method.The interfacial normal strength of the sepcimen is 31.49 MPa and 40.3% higher than that of the untreated sample.The flexural strength and modulus are 828 MPa and 66.1 GPa,which are 21.9% and 25.3% higher than the original CFRP,respectively.The g-CNTs-CFRP composite was also prepared by the matrix reinforcement method.The interfacial normal strength of the sample is 29.5 MPa and 31.4% higher than that of the untreated sample;the flexural strength and modulus are 813.4 MPa and 67.8 GPa,increasing by 21.5% and 25.9%compared with the original CFRP sample,respectively.Based on the failure characteristics of the carbon fiber-epoxy resin interfacial region,the mechanism of g-CNTs enhancing interfacial mechanical property is revealed.Based on the numerical analysis method of the tensile mechanical properties of uniformly distributed g-CNTs-EP nanocomposite and agglomerated epoxy resin,a method to reduce the parameter of resin matrix material in the agglomerated region was proposed,which improved the analysis method of agglomerated distributed g-CNTs-EP.This finite element analysis method improves the prediction accuracy of the mechanical property of gCNTs-EP nanocomposite,and accurately predicts the tensile mechanical property of g-CNTsEP with the loading of 1.5 wt%.The effect of g-CNTs distribution on the mechanical property of g-CNTs-CFRP microcell is studied,and it is found that g-CNTs distributed on the surface or interfacial area of carbon fiber could reduce the damage within the interfacial area.