Abstract
A novel technique has been developed to increase interfacial adhesion be tween organic fibers and thermoplastics. The technique consists of exposing the fiber to a radio frequency plasma discharge and then immediately coating the fiber with thermo plastic while still in the vacuum environment of the plasma reactor. Increased adhesion has been shown using a polyaramid fiber (Kevlar 49) and a polycarbonate resin (Lexan 121). An oxygen plasma exposure of 4.1 seconds at 24 Watts increased interfacial shear strength by 18 % as evaluated using the critical filament length technique. The plasma ex posure had no measurable effect on the filament tensile strength or the surface roughness. It is thought that the enhanced adhesion is due to the presence of covalent bonds formed at the interface when free radicals on the fiber are quenched by the thermoplastic.