Preparation And Properties Of The Waterborne Sizing Agent Applied To Thermoplastic Matrix For Carbon Fiber

Carbon fiber composites are widely used owing to their high strength, light weight, high corrosion resistance, excellent electromagnetic properties, good fatigue resistance, and excellent performance, Among them, the carbon fiber-reinforced thermoplastic composites have attracted a considerable amount of attention in the field of composite materials because of their simplemolding process, shorter production cycle and can be reused. However, the traditional carbon fiber-reinforced composites are thermosetting resin-based matrix, such sizing agents are incompatible with the thermoplastic matrix. Moreover, little research has been done in carbon fiber sizing agent for thermoplastic resin. In particular, the waterborne sizing agent that water as solvent.The solvent of the sizing agent is water, which is an environmental-friendly matter.In the present study, weused thewaterborne polyurethane as a main component, by the addition of inorganic Si O2 and Al2O3 hybrid particles, prepared a carbon fiber waterborne sizing agents forthermoplastic matrix. In order to improve the surface morphology and enhance the surface active carbon fibers, the waterborne sizing agents were used to modify the surface of carbon fiber, and then the composites were prepared. Bonding strengths have significantly increased, providing a reference for the development of carbon fiber reinforced thermoplastic composites.Firstly, on base of the analysis of characteristics of carbon fibers and thermoplastic matrix, we designed a kind of organic-inorganic hybrid coating material(sizing agent) that waterborne polyurethane as a main component. In order to obtain uniform, smallparticle size inorganic hybrid particles,solid acid was used as a catalyst for the hydrolysis of moisture in the air source to prepare a silica-alumina hybrid sol. Then, the sol wasadded to the waterborne polyurethane. Finally,the waterborne sizing agent was synthesized. The size, distribution, viscosity and stability of sizing agent ofthe inorganic particles in the sizing agents were investigated.The results showed thatthe sizing emulsions have a good stability. The particleswere small, narrow particle distribution and best centrifugal stability in the waterborne sizing agent by adding 2%waterborne polyurethane.Secondly, thehigh performance waterborne sizing agent was selected for sizing the carbon fiber. The surface chemical structure, physical morphology and mechanical properties of the carbon firbers were tested via Fourier transform infrared spectroscopy(FTIR), thermal field emission scanning electron microscope(SEM), atomic force microscopy(AFM), etc. The results showed that the activefunctional groups on the surface of carbon fiber were significantly increased after treatedby the waterborne sizing agent and the carbon fiber surface was covered by a layer of the inorganic particle, in addition, the mechanical properties of carbon fiber filaments has also been significantly improved.Finally, the sized carbon fibers and the thermoplasticnylon 6(PA6) were prepared into the composite materials. The effect of sizing agent on the tensile, flexural, thermalstability and interfacial properties of the composites were investigated.The results showed that themechanical and interfacial propertiesof the carbon fiber/PA6 composites were significantly improvedafter adding thewaterborne sizing agent treated carbon fiber.It is indicated that the waterborne sizing agent is a potential and excellent material for the carbon fiber-thermoplastic composites system.