Silicone — Glass Cloth for Solar Glazing

Abstract

OLAR ENERGY PRACTITIONERS continue t o seek better glazing S materials. As part of this search, we are working to combine the durability and dimensional stability of sheet glass with the reduced cost, ease of installation and resistance to breakage of common plastic films. A number of new glazing materials are being introduced to the solar industry. Silicone resin coated glass cloth is an candidate with potential for exceptional durability and strength. Silicones are well known in many industries, including the construction industry, for their outstanding resistance to weathering, insolation, and other extreme environmental forces. This durability results from the basic structure: unlike common polymeric materials, silicones have a chemical structure similar to glass, involving a high energy bond between silicon and oxygen atoms. Silicones are a large class of synthetic materials recognized for suitability in thousands of applications with temperatures ranging from -5OF to over 400F, for use in wet or damp environments, for flame resistance and for their biological inertness [ 1, 21. Recent basic research has also shown that the environmental fate of the most common silicone structure i s a breakdown to ultimately form silicic acid and carbon dioxide, and silicic acid has been shown to support the growth of diatom cultures [31. But unlike other polymers based on carbon atoms, silicones usually do not have sufficient strength to form strong unsupported films like polyethylene or acrylics. This can be overcome by coating silicones on strong fabrics, and glass cloth is preferred, for several reasons: high strength, durability, inertness, and chemical compatibility. Silicone-coated glass'cloth has been used for many years as premium electrical insulation. It is made by running a web of glass cloth through