| Carbon fibers,have been widely applied in a variety of field such as nation defense,aerospace, sports equipments and transportation because of their high specific strength, high specific modulus, wear and corrosion resistance. However, carbon fibers have the low elongation and high brittleness, so they are easy to be caused monofilament fracture and fluff in the production process as long as being bent and rubbed. When the carbon fibers are used as the reinforcing materials of the composites, the broken filaments of carbon fiber influence the compatibility between a matrix resin and carbon fibers, and also make the mechanical properties of whole composite materials greatly reduced. In order to solve above problems,carbon fibers need to be treated with sizing agent.Sizing agent is a layer of polymer intermediate layer which is located between carbon fibers and a matrix resin, and its formulation is considered as confidential information by manufacturers. Currently, the sizing agent used in production lines mostly belongs to solution-based sizing agent. Large amounts of organic solution are used as the solvent of solution-based sizing agent,the evaporation of solvent among sizing agent could not only increases the cost of production, but also results in security risk and environment pollution.Without above worries,waterborne epoxy resin sizing agent using water as dispersion medium or solvent has attracted more and more attention.In this article, phase inversion emulsion method has been used to prepare epoxy resin emulsion type sizing agent by using epoxy resin as main slurry. The using of response surface methodology is to make an optimization study on those factors affecting stability of emulsion in the process of preparation for sizing agent on the basis of single factor experiments.Box-Behnken results show that when the system temperature is 80? stirring speed is 1500rpm, the amount of emulsifier OP-10 is 2.58g, the amount of emulsifier T-60 is 0.89g,the amount of emulsifier SDBS is 0.31g, the minimum average particle size of the emulsion is 46.64?m. In addition to the storage stability, freeze and thaw stability, viscosity, pH value,particle size investigation, particle size distribution under the optimal condition of sizing agents has been tested.Using homemade epoxy resin emulsion type sizing agent makes a sizing treatment on carbon fiber, compared to unsized carbon fiber show that when the mass concentration of the sizing agent is 20%,the surface properties of carbon fiber such as brightness, bundle integrity,and crosslinking have better feature. Scanning electron microscopy' results indicate that compared with unsized one, the surface grooves become unobvious by sizing agents' filling and defects are also reduced significantly.Interlaminar shear strength(ILSS) tests show that, the ILSS of sized carbon fiber reinforced epoxy resin matrix composites is 67.61Mpa, compared with unsized one, the ILSS of composite was improved 7.82%. Composites sectional scanning electron micrograph show that if the carbon fiber reinforced epoxy resin composites after sizing handle are subjected to shear failure, compared with non-sizing handle one, debonding phenomenon between the resin matrix and carbon fiber has been reduced, and interfacial bonding has been greatly improved. |
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