Fabrication Research Of High-strength,High-toughness Self-healing Composite Based On Electrospun Nanofibers

Advanced polymer matrix composites(PMC)made from high performance fibers reinforced polymer matrix have gradually become common lightweight structural materials in aerospace,automotive,sporting goods,construction and other fields due to their unique "light and strong" properties.For the laminated structure of fiber-reinforced polymer,however,the interlaminar fracture failure or delamination usually occurs,due to the existence of the ultra-thin resin intermediate layer with low strength and fracture toughness between adjacent layers.Adding nano-fillers to make the composite material self-repairing is an effective measure to prevent the composite material from delaminating.However,nano-fillers added will degrade the performance of the composites.In order to overcome this shortcoming,functional electrospinning nanofibers were used to modify the carbon fiber reinforced epoxy resin(CF/EP)composites by electrospinning technology,which enabled the composites to have excellent self-healing function and further improved mechanical properties at the same time.The optimal molding process of CF/EP composites modified by electrospun nanofibers was explored,through the analysis of two main factors of pressure and resin content in the molding process of composite molding.Within a certain pressure range,the greater the applied pressure,the fewer voids inside the material,the more compact the composite,and the stronger the performance.Meanwhile,the higher the content of carbon fiber,and the higher the strength of the composite,and the worse the interface performance as the content of resin decreases.However,due to the characteristics of high flexibility,low strength and easy breakage of electrospun nanofibers,the optimal molding pressure was 0.1 MPa,and the maximum pressure in the molding process shall not exceed 0.2 MPa.From the comprehensive consideration of strength and interface performance,the optimal resin content of composites was 40%.Nylon(PA)and Dicyclopentadiene(DCPD)were selected as shell and core materials of functional coaxial nanofibers respectively,and DCPD/PA coaxial fibers were successfully fabricated by electrospinning,and added into CF/EP composite as nanofiber membrane interlayer,a high-strength and high-toughness self-healing composite DCPD / PA-CF / EP was fabricated.The presence of nanofibers increased the flexural strength,fracture strain and fracture work of the composite by 10.59%,11.26% and 53.69%,respectively.Meanwhile,the strength returned to 83.74% of the original level after 2 h of failure.In order to further improve the self-healing ability of the composite,poly(phthalazinone ether sulfone ketone)(PPESK)was used to replace PA.Through the exploration of the electrospinning process,the encapsulation rate of the healing agent DCPD was improved,and the coaxial DCPD/PPESK fibers were added into the composite to prepare the DCPD/PPESK-CF/EP composite.The flexural strength,fracture strain and fracture work of the composite increased by 8.97%,26.14% and 62.12%,respectively.Meanwhile,with the improvement of the encapsulation rate of the healing agent,the healing ability was more significant,and the maximum strength recovery rate of 89.43% could be achieved at the current experimental level,and there was room for further improvement.