Preparation And Properties Of Sizing Agents For Pitch Based Carbon Fiber

Sizing agent is a kind of important assistant material applying on the surface of the carbon fiber.It not only has the effect of protection of carbon fiber,can also enhance the bonding strength between resin matrix and carbon fiber in composite materials.It can improve the interface state of the composite material.Intermediate pitch carbon fiber is a special breed of the carbon fiber family.It has unique performance and application field.But its surface structure has big difference from PAN carbon fiber,therefore it has special requirements for sizing agent.In this article,we choose epoxy resin F-51 which has a good interface bonding strength with pitch based carbon fiber.We prepare water solution and emulsion sizing agents using epoxy resin F-51 as a raw material.The preparation technology is also explored.Using infrared spectrum,centrifugal stability,scanning electron microscope,fiber abrasion resistance and cluster,and the interlaminar shear strength of composite materials,the performance of sizing agent,sized carbon fiber and the performance of the composites are evaluated.Water-soluble epoxy resin is prepared by chemical modification method.When the dosage of diethanolamine is n(epoxide group):n(diethanolamine)=3:1,and the epoxy base ring opening rate is 30%,and the reaction temperature is 80 ?,and the reaction time is 120min,and the neutralization temperature is 60?,modified resin has good water solubility.Its particle size is about 10nm.The quality of centrifugal precipitation is 0.1g/10ml,and stability of aqueous solution meets the requirement.Epoxy resin emulsion is prepared by phase inversion emulsification method.Polyoxyethylene octyl phenol ether,sorbitan monostearate and sodium dodecyl sulfate are chosen as the emulsifier.When the HLB value of the mixed emulsifier is 12,and dosage of emulsifier is 8%,and emulsifying temperature is 70 ?,and the stirring speed is 12000r/min,emulsion particle size of emulsion sizing agent is 5?m to 10?m.The quality of centrifugal precipitation is about 0.1g/10ml,and the emulsion stability is the highest.EP-PU type emulsion sizing agent and EP-PU type water soluble sizing agent are prepared by adding a suitable amount of waterborne polyurethane,which has certain flexibility,to epoxy resin emulsion and Water-soluble modified epoxy resin solution respectively.After the carbon fiber is sized by EP-PU type emulsion sizing agent and EP-PU type water soluble sizing agent,the carbon fiber sizing rate is between 0.8%and 1%.The carbon fiber surface becomes smooth,and the number of carbon fiber abrasion resistance reaches 50-70 times,and the carbon fiber cluster have greatly improved after sizing,and interlaminar shear strength of carbon fiber composites also have greatly improved.When the modified epoxy resin ring opening rate is 30%,and the dosage of polyurethane is 10%,comprehensive performance of sizing agent is best.