Study On The Structure And Properties Of Coated Modified Aramid And Its Composites

Aramid fiber has excellent performance,such as high strength,high modulus,low density,high stability and corrosion resistance,so it is widely used to prepare and improve the performance of composite materials.However,due to the smooth surface,high crystallinity and low surface activity of aramid fiber,the interface performance between the fiber and the matrix material is poor,which seriously limits the application of composites while poor electrical conductivity also hinders its development in flexible wearable electronic devices and special fabrics.In view of the above problems,coating modification is applied to functionalize the fiber surface for enhancing the surface properties of the fiber and the interface effect of the composite material.And on the basis of fiber functionalization,composite highly conductive fibers are prepared.The main research contents of this paper are as follows:(1)Utilize the characteristics of easy protonation and hydrolysis under strong acid conditions to produce active groups applied to coating polyethylene glycol on the surface of aramid fibers.On the one hand,it improves the surface roughness of the fiber,on the other hand,it improves the polarity of the fiber surface,which causes the surface activity of the fiber to increase.The interface between the aramid fiber and the epoxy resin is strengthened due to mechanical occlusion and polarity matching.It’s indicated that the interface performance of the modified fiber-reinforced epoxy resin-based composite material is significantly improved.(2)A hydrogen bond complex of tannic acid and polyethylene glycol is applied on the surface of aramid fiber for improving the surface activity of the fiber.On the one hand,part of the tannic acid is coated on the surface of the fiber,under the bridge action of polyethylene glycol,it interacts with the tannic acid in the solution through hydrogen bonds.On the other hand,the hydrogen bond complex formed by polyethylene glycol and tannic acid is coated on the surface of the fiber through hydrogen bond,π-π interaction,and self-gravity.The introduction of polyethylene glycol is also conducive to the increase of fiber surface activity.The results show that the performance of the fiber will not be damaged during the modification process,and the interface performance between the fiber and the epoxy resin has been effectively improved.At the same time,the composite coating on the surface of the fiber endows the fiber with a certain degree of UV resistance and ensures the excellent performance of the fiber.(3)The composite highly conductive fiber is prepared on the basis of the tannic acid and polyethylene glycol hydrogen bond complex encapsulated fiber.The silver layer is pre-deposited by the redox reaction of tannic acid and silver nitrate on the surface of the fiber.Under the action of glucose,the silver layer becomes denser,which enhances the conductivity of the fiber.When the concentration of silver nitrate is 25 g/L,the electrical conductivity of the fiber is the best,and the surface resistance is as low as 0.20 Ω/cm.As a circuit connection,the small bulb can be successfully illuminated.And the thermal stability of the fiber is improved to a certain extent under the protection of the dense silver layer.