Oxidization of carbon nanofiber and its effect on tensile properties of PAll matrix composite reinforced with carbon nanofiber

In order to improve interfacial adhesion between the thermoplastic matrix and the carbon nanofibers (CNFs), two-step oxidization by using mixed acid and hydrogen peroxide was performed on the CNFs. Moreover, polyamide 11 (PA11) based composites reinforced with the oxidized CNFs were fabricated, and tensile properties of the composite were evaluated. The effect of 2-step oxidization on the tensile properties was discussed. From the results of the X-ray diffraction and XPS, the functional groups including oxygen were introduced to the surface of CNFs by 2-step oxidation process. However, the oxidization by using strong mixed acid destroyed the structure of CNFs excessively. On the other hand, when the mild oxidization by using a hydrogen peroxide was carried out after strong oxidization in a short time, the structure of CNFs was not destroyed and was able to give functional groups including oxygen. As the result, tensile property of the composites reinforced with mild oxidized CNF improved in comparison with the composites reinforced with strong oxidized CNF. It is suggested that the mild oxidization in the second oxidation process was effective to improve the tensile properties of the PA11 matrix composites.