Dielectric properties study of epoxy resin modified with tetraethoxysilane and tetrapropoxysilane in centimeter microwave range

The dielectric properties of epoxy modified with organosilicon compositions, and in particular alkoxysilanes, with the aim of improving its dielectric characteristics in microwave radio frequency range were studied. Tetraeth-oxysilane and tetrapropoxysilane introduction into epoxy material is stated to improve hydrophobic properties of the developed compound considerably. The research revealed that dielectric permeability largely depends on both alkoxysilane nature and on its structure. The relation of dielectric loss tangent at 9.8 GHz frequency and alkoxysilane amount has been determined. Dielectric loss was stated to be considerably lower in compositions modified with alkoxysilanes as compared with unmodified epoxy resin. The best effect is achieved when tetraethoxysilane is used as a modifier with the concentration from 2 to 4 %. Regardless alkoxysilane nature, a significant increase of dielectric loss is observed at the concentration over 5 %. The carried out research defined that water absorption of modified materials by alkoxysilanes is much lower than of unmodified. It causes dielectric loss reduction and consequently high stability of electric properties of epoxy based materials during the operation. Keywords: epoxy resin, alkoxysilane, tetraethoxysilane, tetrapropoxysilane, dielectric properties, the composite material, microwave-radio frequency range.