Interfacial aspects of electrodeposited carbon fiber-reinforced epoxy composites using monomeric and polymeric coupling agents

Using a monomeric and two polymeric coupling agents, interfacial aspects of electrodeposited (ED) carbon fiber/epoxy composites were investigated by m eans of fragmentation techniques and acoustic emission (AE). ED results for dipped and untreated fibers under dry and wet conditions were compared. Mu ltifiber-embedded composites (MFC) were prepared for direct comparison. Var ious treating conditions such as treating time, concentration of coupling a gent, and treating temperature were optimized, respectively. The adsorption mechanisms of the coupling agents onto the carbon fiber were analyzed in t erms of the electrolyte molecular interactions during ED process, due to ch ain mobility in the aqueous solution. The microfailure mechanisms occurring from fiber breaks, and matrix and interlayer cracks were examined by AE pa rameters. The interfacial shear strength (IFSS) of ED-treated carbon fibers was much higher than that of the other two cases under dry and wet conditi ons. Well-separated AE groups were found for the untreated, the dipped, and the ED-treated cases, and significantly more AE events occurred from the E D interlayer failure between fiber and matrix than from the untreated and e ven than from the dipping cases. AE events from different-type interlayers may be correlated with IFSS based on the differing mechanical and chemical roles of the interlayers. (C) 2000 Academic Press.