Glass fiber surface effects in silane coupling

Glass fibers with the nominal E-glass composition were synthesized with 0, 2, 4, or 6% B₂O₃. The influence of the B₂O₃ content on aminosilane adsorption was evaluated using X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. The water adsorption capacity of the silane-treated fibers was measured using a gravimetric technique. It was found that the presence of B₂O₃ enhanced the adsorption of aminosilane, but, more significantly, it greatly increased the water adsorption capacity of the silane-treated fibers. This effect of the B₂O₃ on water adsorption was considerably less evident in the untreated fibers. The solubility of boron and aluminum appears to play a role in determining the chemical and physical structure of the silane overlayer.