Fourier transform infrared spectroscopic study of the structure of silane coupling agent on E-glass fiber

Abstract

Infrared spectra of silane coupling agents deposited on E-glass fiber were obtained by Fourier transform infrared spectroscopy (FT-IR). A spectral subtraction technique resolved all vibrational modes of the coupling agent deposited from various concentrations of treating solutions. The amount of vinyl functional coupling agent was determined by measuring the integrated peak intensities of the organic functional group. It revealed that the thickness of the coupling agent layer on the glass fiber depended on the concentrations of the treating solution. The rates of condensation reaction of polysiloxanol with and without glass fiber were followed. The coupling agent on the glass fiber reacted much faster than without glass at room temperature. It was concluded that the coupling agent molecules near the glass fiber surface have some order and can easily participate in the condensation reaction. The carbonyl group of a methacryl functional silane hydrogen bonds with hydroxyl groups. The methacryl functional silane on the glass fiber showed less hydrogen bonded groups than the precipitated polysiloxanol suggesting a mechanism of predominant head-to-head adsorption.