Adhesion: Comparison between physico-chemical expected and measured adhesion of oxygen-plasma-treated carbon fibers and polycarbonate

The adhesive interaction between oxygen-plasma-treated, polyacrylonitrile-b ased, high-tensile-strength carbon fibers and a polycarbonate matrix has be en studied. Several models have been used to predict the impact of the plas ma treatment process on the strength of adhesion between both jointing part ners. These approaches have been the thermodynamic work of adhesion which w as calculated from the solid surface tensions, based on the results of cont act angle measurements versus test liquids, the contact angle which was dir ectly obtained via polycarbonate melt droplets on single carbon fibers and the zeta (zeta)-potential data provided by streaming potential measurements . The results have been compared with the interfacial shear strength determ ined from the single-fiber fragmentation test. Additionally, the single-fib er tensile strength of the oxygen-plasma-treated carbon fibers was determin ed. We confirmed that any physico-chemical method on its own fails to describe exactly the measured adhesion. However, for the investigated system, the co nscientious interpretation of the data obtained from wetting measurements, in conjunction with the thermodynamic approach, is sufficient to predict th e success of a modification technique which has been applied to one compone nt in order to improve adhesion.