Study On The Surface Modification Of Carbon Fiber By Phenol Formaldehyde And Carboxyl-terminated Butadiene-acrylonitrile

In the field of CFRP,the application of T300 carbon fiber is more extensively used,but the fiber has the disadvantage of poor adhesion with the matrix,which leads to the existence of more defects in the interface of CFRP,often debonding under some external force at the interface,which directly leads to the serious influence on the mechanical properties of the composites and limits the high performance of the carbon fiber in the composite.In this paper,a method of phenol formaldehyde resin(PF)and carboxyl-terminated butadiene-acrylonitrile rubber(CTBN)compounded surface modifier(PF-CTBN)carbonizing on the surface of fiber was proposed.There is no other scientific research units and individuals researching about PF-CTBN carbonizing on the surface of carbon fiber to improve its interface shear strength reported before.Therefore,the research of this paper has very important value.In this paper,the mixing and charring behavior of PF and CTBN were studied.The best ratio of PF and CTBN was determined as the ratio of PF: CTBN = 9: 1.The thermogravimetric analysis,Structure analysis is used to study the carbonization mechanism of PF-CTBN and the influence of the presence of CTBN on the process of PF carbonization.In this paper,the surface modification of carbon fiber is related to the heat treatment,which will inevitably affect the tensile strength of the monofilament of the carbon fiber.Therefore,the tensile strength of T300 carbon fiber treated with different carbonization temperature is studied.When the temperature reaches 800oC,the tensile strength of monofilament is 48.3% lower than that of T300,and the structure of the body is severely damaged.It can be considered that the carbon fiber has failed and can no longer be used as a reinforcement.So the carbonization temperature as much as possible under the control of 600oC to ensure that the carbon fiber body tensile strength.In order to reduce the concentration of PF(PF-CTBN),butanone is used as solvent to dissolve PF and PF-CTBN.In this paper,the effects of modifier PF(PF-CTBN)concentration and carbonization temperature on the properties of modified carbon fiber were investigated.PF-CTBN has better modification efficiency.The optimum conditions are PF-CTBN concentration of 1:80 and carbonization temperature of 600oC.This concentration can ensure that PF-CTBN is suitable for coating on carbon fiber surface.This temperature can ensure that PF-CTBN in the carbon fiber surface is fully carbonized and not excessive,but also ensure that the carbon fiber to maintain a certain degree of body tensile strength.Under the optimum conditions,the interfacial shear strength increased to 128 MPa,which was 36.17% higher than that of T300.The modification method proposed in this paper can improve the bonding performance between the fiber and the matrix,and can maximize the role of the reinforcement in the composite material.