Evaluation of the effect of a custom fiber surface treatment on the adhesion level in a polymer-based composite using the single fiber fragmentation test

During the past several years, a number of investigations have focused on i mproved fiber surface treatments as well as the development of micromechani cal experimental techniques to accurately evaluate the fiber/matrix adhesio n level. The aim of this study was to evaluate the effect of a custom fiber surface treatment on the fiber/matrix adhesion level of a carbon fiber rei nforced, polymer matrix composite material. Single fiber fragmentation test s were performed on specimens produced using EPON 828 resin and AU-4 fibers , AS-4 fibers, and AU-4 fibers that were treated with a custom fiber surfac e treatment known to lead to direct chemical reaction with the EPON 828 res in. Qualitative inspection of the birefringent stress patterns produced by the custom treated fiber indicate a high level of fiber/matrix adhesion, gr eater than the adhesion exhibited by either of the two as received fiber ty pes. In addition, the custom treated fibers produced an average fiber fragm ent length approximately 23% shorter than the AS-4 specimens, indicating a rather significant increase in adhesion level for the custom treated fibers over the commercially treated fibers. Calculated interfacial shear strengt h values follow the same trend as was seen during the evaluation of the ave rage fragment length values.