The Effect Of Sizing Agent On The Surface Of T800 Carbon Fibers And The Interphase Properties Of Their Composites

The carbon fiber/resin matrix composites are widely used in the many fields. The interphase is composed of two parts that are between fiber and sizing agent and between sizing agent and matrix. The sizing agent can reacted with the surface of carbon fiber, which is the important role in the composites.First, this paper aimed to study the effect of heat treatment on the surface properties of T800 grade carbon fibers and the interface properties of carbon fibers reinforced epoxy composites. This paper investigated two different carbon fibers (T800-1, T800-2), and the effect of sizing agents on the carbon fiber surface properties. Carbon fibers were heat-treated and then went through modifying to study the properties. The results of the study indicate that the heat treatment temperature of carbon fibers has an important influence to the carbon fibers composites due to the reactivity of sizing agent. This is due to different surface morphology, different amounts of functional groups, different kinds of sizing agent and different preparation conditions on T800-1 and T800-2 carbon fiber surface. Heat treatment contributes to the main enhancement of chemical interaction between T800-1 carbon fibers in the composites, while the trenches developed on the T800-2 can contribute to the physical interaction more.Second, this paper aims to study impact of coated different functionalized and contents of CNCs(cellulose nanocrystals) in the sizing agent(aq) on interfacial properties of T800 carbon fibers with epoxy (EP) resin matrix. Different functionalized and contents of cationic CNCs(cellulose nanocrystals) in the sizing agent(aq) result in different effects. The results show that the properties of cationic CNCs coating on the surface of carbon fibers is better than tempo CNCs at the same content. And with the same CNCs on the surface on the carbon fibers, the properties of 0.5wt% is best of all.In conclusion, sizing agent reacts with functional groups on the surface of T800 carbon fiber by heat treatment process. And sizing agent reacts with grooves on the surface of the carbon fiber. The reaction changed the sizing agent on the surface of carbon fiber, making the composite interphase performance change. The cationic cellulose nanocrystals make the composite interphase performance better than tempo CNCs on the surface of carbon fibers, both of which can enhance the interfacial properties of composites. In addition, the 0.5wt% cationic cellulose nanocrystals make the composite interphase performance better.