According to the form and length, glass fiber can be divided into continuous fiber, fixed length fiber and glass cotton; according to the glass composition, it can be divided into alkali free, chemical resistant, high alkali, medium alkali, high strength, high elastic modulus and alkali resistant (alkali resistant) glass fiber, etc.

The main raw materials for producing glass fiber are quartz sand, alumina and pyrophyllite, limestone, dolomite, boric acid, soda ash, mirabilite, fluorite, etc. There are two kinds of production methods: one is to make the fused glass into fiber directly; the other is to first make the fused glass into a 20 m m diameter glass ball or bar, and then heat and remelt it in various ways to make a very fine fiber with a diameter of 3-80 μ M. The infinite fiber drawn by mechanical drawing method through platinum alloy plate is called continuous glass fiber, which is generally called long fiber. The discontinuous fiber made by roller or air flow is called fixed length glass fiber and short fiber.

Glass fiber is divided into different grades according to its composition, property and use. According to the standard level (see table), class E glass fiber is widely used and widely used in electrical insulation materials; class s is special fiber.

Glass used in the production of glass fiber is different from other glass products. The internationally commercialized glass components for fibers are as follows:

E- glass

Also known as alkali free glass, is a borosilicate glass. At present, it is a widely used glass component for glass fiber, which has good electrical insulation and mechanical properties. It is widely used in the production of glass fiber for electrical insulation, and also widely used in the production of glass fiber for FRP. Its disadvantage is that it is easy to be eroded by inorganic acid, so it is not suitable for use in acid environment.

C- glass

It is also called medium alkali glass, which is characterized by better chemical resistance, especially acid resistance than non alkali glass, but poor electrical performance, mechanical strength 10% - 20% lower than non alkali glass fiber. Generally, foreign medium alkali glass fiber contains a certain amount of boron dioxide, while China's medium alkali glass fiber does not contain boron at all. In foreign countries, medium alkali fiberglass is only used to produce corrosion-resistant fiberglass products, such as fiberglass surface felt, etc., and also used to strengthen asphalt roofing materials. However, in China, medium alkali fiberglass accounts for more than half (60%) of the fiberglass production. It is widely used in the production of fiberglass reinforcement, filter fabric, binding fabric, etc., because its price is lower than that of non alkali glass Fiber has a strong competitiveness.

High strength glass fiber

It is characterized by high strength and high modulus. Its tensile strength of single fiber is 2800mpa, about 25% higher than that of alkali free glass fiber, and its modulus of elasticity is 86000mpa, higher than that of E-glass fiber. The FRP products produced by them are mostly used in military industry, space, bulletproof armor and sports equipment. However, due to the high price, it can not be popularized in civil use, and the world's output is about several thousand tons.

Ar glass fiber

Also known as alkali resistant glass fiber, alkali resistant glass fiber is the rib material of glass fiber reinforced (cement) concrete (GRC) and is 100% inorganic fiber, which is an ideal substitute for steel and asbestos in non load bearing cement components. Alkali resistant glass fiber is characterized by good alkali resistance, effective resistance to the erosion of high alkali substances in cement, strong grip, high modulus of elasticity, impact resistance, tensile strength and bending strength, strong resistance to combustion, freezing, temperature and humidity change, excellent crack resistance and permeability resistance, strong designability and easy forming. Alkali resistant glass fiber is widely used in high-performance reinforcement（ Cement) is a new type of environmental protection reinforced material in concrete.

A glass

Also known as high alkali glass, it is a typical sodium silicate glass, because of its poor water resistance, it is rarely used to produce glass fiber.

E-CR glass

It is a kind of improved boron free and alkali free glass, which is used to produce glass fiber with good acid and water resistance. Its water resistance is 7-8 times better than that of alkali free glass fiber, and its acid resistance is also much better than that of alkali free glass fiber. It is a new type specially developed for underground pipelines, tanks, etc.

D glass

Also known as low dielectric glass, it is used to produce low dielectric glass fiber with good dielectric strength.

In addition to the above glass fiber components, there is a new alkali free glass fiber, which is completely boron free, thus reducing environmental pollution, but its electrical insulation and mechanical properties are similar to the traditional E glass. In addition, there is a kind of glass fiber with double glass components, which has been used in the production of glass wool, and it is said that it has potential in the use of glass fiber reinforced materials. In addition, there are non fluoride glass fiber, which is an improved non alkali glass fiber developed for environmental protection.

Identification of high alkali fiberglass

The simple test method is to boil the fiber in boiling water for 6-7h. If the fiber is high alkali glass nitrate fiber, after boiling water, the warp and latitudinal fibers become loose.

According to different standards, there are many classification methods of glass fiber, generally from the two angles of length and diameter, composition and performance.