ABSTRACT
This chapter analyzes experimental approaches concerning wettability measurements onto single fibers. It deals with the analysis of capillary impregnation of “plugs” constituted by divided solids, like powders or fibers, as well as of fiber fabrics. The tensiometric method, in one or two liquid phases, is largely used nowadays to determine the thermodynamic surface properties of fibers, whatever the nature of these latter. This is particularly the case for cylindrical and rigid fibers, like glass and carbon but also polymeric fibers, which can easily penetrate into the liquid phases without bending. Washburn’s approach can also be applied to fibrous systems—in particular, woven fabrics—whatever the nature of the fibers. The authors have determined the ratio of oxygen atoms present on the surface for the different carbon fibers by means of x-ray photoelectron spectrometry. Several investigators have shown that the strength of the particle–polymer interfaces affects the yield stress of the reinforced materials and that poor adhesion tends to decrease this yield stress.
