Nano-analysis on the structure and chemical composition of the interphase region in carbon fiber composite

Detailed morphology of intact interphase and chemical compositions were investigated for carbon fiber/epoxy composite. The transmission electron microscopy (TEM) images revealed textures of oriented graphite crystallite and fibril in fiber cortex, and interphase located in-between the fiber and the amorphous matrix with the thickness to be about 200 nm. Structure variation through the interphase was demonstrated by plasmon energy values subtracted from the zero-loss peak. The electron energy loss spectroscopy (EELS) showed changes in chemical bonding states of different phase regions, and gradient decrease of oxygen to carbon ratio was observed from the matrix to the fiber.