The liquid glass is formed at 1600 ° C from a mixture of mineral products (sand, kaolin, rock, limestone, calcium borate). The liquid is passed through the micron holes of the bushing and cooled simultaneously until warps or glass fibers with a diameter of 5-24 microns are produced. The warps are pulled together to form a “bundle of strands” or are loosely coupled to form a “roving”. The strands are covered with a starch to ensure the interconnection of warps and glass resistance against abrasion.
Various types of GPR with various applications are produced by modification of manufacturing instructions:
Type A fiberglass: Includes alkaline and shows good resistance against acid.
– Type E (electric) fiber glass: contains a lower percentage of alkaline and is stronger than type A fiber glass (alkaline), this fiber glass enjoys favorable tensile and compressive strength and good stiffness, provides optimal electrical insulation and is relatively inexpensive. However, its resistance is relatively weak. In the polymer matrix composite industry, the type E fiberglass is known as the most commonly used GPR.
– Type C (chemical) fiber glass: shows the best resistance to chemicals and is mainly used as tissue in the outer or inner layer of the multi-layered tubes or containers adjacent to chemicals and water.
– Type S fiber glass is of high strength and is used mostly in military industry.
– ECR type fiber glass: type of glass integrates the electrical and mechanical properties of type E fiberglass and the chemical resistance of type C fiberglass. This type of fiberglass also enjoys higher thermal and dielectric properties compared to type E fiberglass, and is environmentally friendly due to being boron-free.
R, S, or T-type fiberglass are brand names for fibers that have higher tensile and module strength than the type E fiberglass and can better maintain their strength in wet environments. Due to smaller diameter of strands, this type of fiber has favorable inter-layer shear strength (ILSS). Type S fiberglass is manufactured by OCF in the United States and by AGY in the UK, type R fiberglass is manufactured by Vetrotex factory in Europe and type T fiberglass is produced by Nittobo Co. in Japan. These fibers are mostly used in Aerospace and defense industries and also have some ballistic applications.