Interfacial aspects of electrodeposited conductive fibers/epoxy compositesusing electro-micromechanical technique and nondestructive evaluation

Interfacial adhesion and nondestructive behavior of the electrodeposited (E D) carbon fiber reinforced composites were evaluated using the electro-micr omechanical technique and acoustic emission (AE). Interfacial shear strengt h (IFSS) of the ED carbon fiber/epoxy composites was higher than that of th e untreated case. This might be expected because of the possible chemical a nd hydrogen bonding based on an electrically adsorbed polymeric interlayer. Logarithmic electrical resistivity of the untreated single-carbon fiber co mposite increased suddenly to infinity when the fiber fracture occurred, wh ereas that of the ED composite increased relatively broadly up to infinity. This may be due to the retarded fracture time as a result of the enhanced IFSS. In single- and 10-carbon fiber composites, the number of AE signals c oming from the interlayer failure of the ED carbon fiber composite was much larger than that of the untreated composite. As the number of each first f iber fracture increased in the In-carbon fiber composite, the electrical re sistivity increased stepwise, and the slope of logarithmic electrical resis tance increased. In the three-graphite filament composite with a narrow 1 t ime inter-filament distance, the total numbers of the filament fracture and the IFSS were smaller than those of the wider 5 times case. This might be because the interacting fracture energy caused by a filament break could af fect the adjacent filaments. (C) 2001 Academic Press.