Properties Of Modified Carbon Nanotube/epoxy/aramid Fiber Composites

In this paper,the multi-walled carbon nanotubes(MWCNTs) were chemically treated,and then the liquid thiol oligomer(TO) was grafted to obtain thiol oligomer grafted multi-wall carbon nanotubes(MWCNTs-TO),improve the dispersibility of MWCNTs in epoxy resin(EP),combine the modified EP curing system with aramid fiber(AF) to prepare MWCNTs-TO/EP/AF ternary composite material to improve the mechanical properties of the composite material.First hydroxylated MWCNTs,then silanized,and finally grafted TO to obtain MWCNTs-TO with a grafting rate of 11.4wt%.Infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TGA),scanning electron microscopy(SEM)were used to analyze and characterize the molecular structure and composition changes of each reaction stage during the modification of MWCNTs.MWCNTs-TO/EP composites were prepared by using MWCNTs-TO as the nano-reinforced particles and liquid low molecular weight polyamide(PA) curing agent to synergistically cure EP.The mechanical properties and thermal properties of MWCNTs-TO/EP were tested.The results show that with the increase of MWCNTs-TO content,significantly improve the tensile strength,bending strength and impact strength of the composite materials,increased by 59.6%,34.8% and 55.4%,respectively.The mechanical properties of MWCNTs-TO/EP composites were analyzed by thermogravimetric analysis(TGA)and dynamic thermomechanical analysis(DMA).The results show that the T_g of composites is significantly improved with the increase of MWCNTs-TO content,which the maximum value with 0.75wt% content,while the heat resistance and thermal stability have been significantly improved.The morphology of MWCNTs-TO/EP was characterized by SEM.It was found that the interface bonding state between MWCNTs-TO and EP matrix was good.Through the mechanical properties test of MWCNTs-TO/EP/AF composite materials,it was found that the TO molecules in the interface layer are beneficial to buffer,absorb and eliminate the internal stress that the composite material bears,which has a great influence on the mechanical properties of the composite material.When the content of MWCNTs-TO in the ternary composite is 0.75 wt%,the mechanical properties are maximized,compared with EP/AF composites,the flexual strength were increased by 58.47%,the tensile strength were increased by 44.08%,and the impact strength were increased by 88.33%.