There are several high-strength glass - S glass

When you need more strength, high-strength glass become an option, it was first developed in the 1960s and used for military applications.alkali-free or E glass, it’s named by its chemical composition, which is an excellent electrical insulator, which is particularly suitable for application to the desired radio signal, better transparency areas, such as aircraft radomes, antennas and printed circuit board. Manufacturers are constantly adjusted S glass formulations. 

At least 50% of E- glass fiber is made of silica oxide;fiberglass chopped strand Glass ball Manufacturers mat the rest consisting of aluminum, boron, calcium and / or other compounds, also include limestone, fluorite, boric oxide and clay.. It has become the standard form of glass fiber, accounting for more than 90% glass fiber reinforced materials. The new S-3 UHM (ultra-high modulus) glass, for example, AGY (Aiken, SC, USA) launched a tensile modulus of the new S-3 glass has 14,359 in - higher than the S- glass and 40% higher than E glass - due to improved manufacturing and proprietary additives and melt chemistry of the fiber. 

The amount of silica aluminum oxide and magnesium oxide in S- glass has significantly more than E glass, it is stronger 40-70% than E glass. Although this two types of fibers in this elevated temperature range still showed unusual strength. At the same time, it is also the most economical glass fiber composite materials to meet at a relatively low cost in many applications, which will provide enough performance requirements strength. 

There are several high-strength glass - S glass in the United States, R- glass in Europe, and T glass in Japan, the strand tensile strength is about 700 ksi, it has a high tensile modulus of 14 Msi.When the temperature is up to 540℃, the strength of E glass and S glass will lose a half