Surface amination and hydrolyzation of carbon fibers treated with triethylene tetramine in supercritical water/ethanol system

To improve the interfacial properties between carbon fibers and epoxy matrix, the fibers were treated by an ammoniac medium, which consisted of supercritical water, ethanol and triethylene tetramine. The images of atomic force microscopy and scanning electron microscope indicate that coating layers are formed on the surfaces of treated fibers. The results of X-ray photoelectron spectroscopy demonstrate that N content on the surfaces of carbon fibers increases and the main ammoniac groups of the coating layers are amino and imino groups. The mechanical measurements indicate that both interlaminar and interface shear strength of carbon fibers are significantly increased after amination.