Viscoelastic and Processing Effects on the Fiber-Matrix Interphase Strength. Part III. The Effects of Postcure

A novel method for tailoring the interphase of carbon fiber-polymer composites by resistive electric heating is presented. The single-fiber fragmentation test is used to investigate the adhesion and fracture properties of the interphase. Electric resistive heating is shown to increase adhesion and toughness at the interphase region. In analyzing the results, the strength and fracture energy of the interphase are related to the thermal postcure conditions created by resistive electric heating. For this purpose, a difference analysis method is used to obtain a numerical solution for the heat conduction problem in the single-fiber test specimen and the temperature distributions are determined. Improvements obtained by using resistive electric heating of the carbon fiber are compared with those obtained by postcuring of the whole sample via convective thermal postcuring. The results obtained using these two different postcure methods seem to be similar.