Surface characteristics of domestic T800-grade carbon fibers and microscopic interphase properties of composites

The surface properties of two domestic T800-grade sized and desized carbon fibers were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The micro-interface shear strength (IFSS) of single fiber composites was also analysed by single fiber fragmentation test (SFFT). The influences of surface properties on micro-interphase strength of single carbon fiber composites and hygrothermal properties were investigated. The results show that the amount of surface active functional groups decreases and surface roughness increases, but the interfacial adhesion between fiber and matrix enhances after desizing. In addition, the hygrothermal environments dramatically decrease the micro-interphase strength, especially degrade the chemical bond force on the interphase, but interphase properties can partially recover after humidity desorption.