The Effects Of Atmospheric DBD Plasma Treatment And Grafting On The Surface Properties Of Pan Based Carbon Fiber

Plasma treatment has been seen as an effective and environmental friendly method of modification. And in recent years, it has been increasingly used in the field of fiber surface treatment. Plasma treatment on carbon fiber now is still in the experimental stage. Most researches have demonstrated that the oxygen group can be introduced onto the fiber by plasma treating, which resulted in the improvement of the activity and interface bonding of the surface.In this recent study, atmospheric dielectric barrier discharge (DBD) plasma has been introduced to investigate the effects of plasma treating time and voltage on the surface properties of carbon fiber. Based on this, the ethylene glycol was grafted before and after plasma treatment, and different densities of the monomer were also compared. To analyze the surface morphology, chemical composes, the wettability and surface bonding of the fiber, the testing methods of scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), dynamic contact angle test and single fiber composite test were performed.The results indicated that the surface properties have been greatly improved after plasma treating, and reached the best when treated under 6kv voltage with 90s duration. The plasma could eliminate the impurity other than etching the fiber. XPS analysis showed that the polar group increased significantly as the plasma treatment prolonged to 90s, however, the active groups just formed can be partly eliminated by the plasma after 90s. Different voltage also can affect the chemical composes, and 6kv was the most desirable. The Weibull analysis of the tensile data revealed no substantial changes in the tensile strength within the treatment time of 180s. The results of the contact angle and SFC test showed the interface property in line with the contents of oxygen containing group, and when treated with 90s under 6kv, the surface energy and IFSS value reached the top, which increased for 24% and 47% respectively compared to the untreated fiber.The results showed in the plasma grafting indicated that the grafting before plasma treatment was more advisable compared to the method grafting after the plasma treating, and the optimum concentration of monomer was 0.05mol/L. When the high energy plasma particle strike on the interface between the ethylene glycol and carbon fiber, it is easier to etch the surface than directly hitting onto the carbon fiber. Furthermore, the monomer can make full use of the plasma particle, which contributes a lot to the oxidation and activation of the carbon fiber. The IFSS increased for 77.7% and 39.3% when grafted before and after plasma, compared to the IFSS of the untreated fiber.It is obviously that the carbon fiber obtained better interfacial bonding by plasma grafting compared to the plasma treatment alone, which indicates that the plasma grafting may be more applicable in the field of surface modification of carbon fiber.