Differentiation of silane adsorption onto model E-glass surfaces from mixed solutions of amino and glycidyl silanes

Mixed silanes are often used as coupling agents in sizings for glass fibres. A technique has been developed which enables the preferential adsorption of a particular silane onto a model E-glass from a mixed aqueous silane solution to be probed. It is shown that け-Aminopropyltriethoxysilane (APS) is preferentially adsorbed over け-glycidoxypropyltrimethoxysilane (GPS) onto model E-glass fibres. High resolution X-ray photoelectron spectroscopy (XPS) has been employed to investigate the nature of silane deposits. Differentiation between the hydrolysed silane deposit and the model silica-based glass substrate was achieved by Si2p curve fitting. The extent of total silane adsorption onto model E-glass fibres was determined from the intensity of CSiO3 peak. In the case of APS/GPS mixed silanes, the N1s peak intensity provides the concentration of APS in the deposit. By comparing the relative intensities of the components in the Si2p3/2 and Si2p1/2 peaks for SiO4 and CSiO3 with the intensity of the N1s peak an assessment of differential adsorption proved possible.