STRENGTHENING OF GLASS RODS WITH ORMOSIL POLYMERIC COATINGS

The strengthening of abraded glass rods, with an average strength similar to that of commercial glassware, by the application of an ormosil polymeric coating composed of a silane with an epoxy resin is reported in detail for the first time. These coatings are applied from solution in an organic solvent by either dipping or spraying and have a thickness in the range 3-10 mu m. For the formation of effective coatings it is necessary to control their composition, prereaction of the silane and application conditions. Subsequently, it is essential that the resin is 'fully' cured and that good adhesion between the coating and the glass surface is achieved. An approximate calculation of the stress in the coating shows that it is tensile. Hence the role of these coatings, which can increase the measured strength of glass rods by up to 100%, depends on the chemical interfacial reaction between the coating and Griffith flaws in the glass surface.