The Research Of Supercritical Fluid For Surface Treatment Of Carbon Fiber

Carbon fiber has high strength and high modulus, so it has been widely used, because of the carbon fiber surface is smooth, surface energy and low performance, seriously affecting the carbon fiber and resin interface between the performance, this paper using supercritical H₂O₂ on the carbon fiber surface oxidation and supercritical TETA coated carbon fiber surface treatment, attempt to increase the carbon fiber surface roughness, to improve between the fiber and matrix invasion and increase of carbon fiber and resin matrix interfacial bonding.Results show that the weaker layer of carbon fiber surface is removed by the Supercritical H₂O₂ oxidation. According to scanning electron microscopy (SEM) and atomic force microscope (AFM) results show that: as compared with the untreated carbon fiber, the grooves after treatment become widened and deepened, and the surface roughness is also increased one-fold. Photoelectron spectroscopy (XPS) spectra obtained: the functional groups on the carbon fiber surface are increased after the Supercritical H₂O₂ oxidation, as confirmed by the O/C atomic ratio is increased. But the oxidation treatment on the weak layer of graphite fiber surface damage, resulting in lower fiber body strength, the use of interlayer shear strength (ILSS) and interfacial shear strength (IFSS) to evaluate the mechanical properties of carbon fiber composite materials, oxidant content is not higher, composite materials(CFRP) the better the performance, the test results obtained, the best state of oxidation when the oxidizing agent 3ml, IFSS increased from 82.27MPa to 106.66MPa, ILSS from 62.10MPa increased to 70.75MPa, treated carbon fiber surface roughness and oxygen groups, respectively, are two reasons for the increase, the mechanical properties improved.Supercritical TETA coated carbon fiber surface treatment, by SEM and AFM observation on the fiber surface, with no coating of the fiber surface compared to the modified fiber surface becomes rough from the smooth, showing different degrees of uplift, according to XPS test structures show that the surface of the fiber N, O elements of a significant increase, which proved surface amino group increment to be a stimulative factor on the interface capabilities of epoxy resin to CFs. But by IFSS and ILSS test results show that the composites do not increase with the TETA content increase, the test results obtained, the best state of oxidation when the TETA contents 0.4ml, IFSS increased from 131.69MPa to 161.88MPa, ILSS from 62.10MPa increased to 78.25MPa, modified the interface between fiber and resin combination of performance has been improved, the mechanical properties improved.Supercritical H₂O₂ on the carbon fiber surface oxidation and supercritical TETA coated carbon fiber surface treatment are to extent improve the wettability between fiber and resin, the purpose to improve the fiber and matrix resin mechanical meshing capabilities, in order to improve the mechanical properties of composite materials.