Glass fibers (formerly known as glass fibers or fiber glass) are a kind of inorganic non-metallic materials with excellent properties. They have many kinds. Their advantages are good insulation, heat resistance, corrosion resistance and high mechanical strength, but their disadvantages are brittleness and poor wear resistance. It is made of glass ball or waste glass by high temperature melting, drawing, winding, weaving and other processes. Its monofilament diameter is several microns to more than twenty meters microns, equivalent to 1/20-1/5 of a hair filament. Each bundle of fibers is composed of hundreds or even thousands of monofilaments. Glass fibers are usually used as reinforcing materials in composite materials, electrical insulation materials and insulation materials, circuit substrates and other fields of national economy. The general idea of glass is that hard and fragile objects are not suitable for use as structural materials, but when they are drawn into silk, their strength is greatly increased and they are flexible. Therefore, they can finally become excellent structural materials with the shape given by resins. Glass fiber decreases with its diameter and its strength increases. The characteristics of raw materials and their applications are introduced. Glass fibers are better than organic fibers in temperature resistance, non-flammability, corrosion resistance, heat insulation and sound insulation (especially glass wool), high tensile strength and good electrical insulation (such as alkali-free glass fibers). But it is brittle in nature and poor in wear resistance. Glass fibers are mainly used as electrical insulation materials, industrial filter materials, anti-corrosion, moisture-proof, heat insulation, sound insulation and shock absorption materials. It can also be used as reinforcing material to manufacture reinforced plastics or rubber, reinforced gypsum and reinforced cement. The flexibility of glass fiber coated with organic materials can be improved. It can be used to make packaging cloth, window screen, wall cloth, covering cloth, protective clothing, insulation and sound insulation materials. As a reinforcing material, fiberglass has the following characteristics. These characteristics make the use of fiberglass far wider than other kinds of fibers. The development speed of fiberglass is also ahead of its characteristics listed below.

(1) high tensile strength and small elongation (3%).

(2) high elasticity coefficient and good rigidity.

(3) the elongation within the elastic limit is large and the tensile strength is high, so the impact energy is large.

(4) inorganic fibers, which are non flammable and highly resistant to chemicals.

(5) water absorption is small.

(6) the scale stability and heat resistance are all good.

(7) good workability, and can be made into different forms of stock, bundle, felt and weaving.

(8) transparency can be transmitted through light.

(9) development of surface treatment agent with good resin adhesion.

(10) the price is cheap.

(11) it is not inflammable and can be melted into small glassy beads at high temperature.

Main components

Its main components are silica, alumina, calcium oxide, boron oxide, magnesium oxide and sodium oxide. According to the alkali content of glass, it can be divided into alkali-free glass fibers (0%-2% sodium oxide, belonging to aluminoborosilicate glass), medium-alkali glass fibers (8%-12% sodium oxide, belonging to boron-containing or boron-free sodium calcium silicate glass). And high alkali glass fiber (sodium oxide more than 13%, sodium calcium silicate glass). According to shape and length, glass fibers can be divided into continuous fibers, fixed length fibers and glass wool. According to glass composition, glass fibers can be divided into alkali-free, chemical-resistant, high alkali, medium alkali, high strength, high elastic modulus and alkali-resistant glass fibers.

The main raw materials for glass fiber production are quartz sand, alumina and pyrophyllite, limestone, dolomite, boric acid, soda, mirabilite, fluorite, etc.

There are two kinds of production methods: one is to make fibers directly from molten glass; the other is to make glass balls or rods with a diameter of 20 mm first, and then to make very fine fibers with a diameter of 3-80 microns after reheating and remelting in various ways. The infinite length of fibers drawn by mechanical wire drawing through platinum alloy plates is called continuous glass fibers, commonly known as long fibers. A discontinuous fiber made of rollers or airstreams is called fixed length glass fiber, commonly known as staple fiber. A fine, short and flocculent fiber made of centrifugal or high-speed airflow is called glass wool. After processing, glass fibers can be made into various forms of products, such as yarn, twistless roving, chopped raw silk, cloth, tape, felt, board, tube, etc.

Glass fibers are divided into different grades according to their composition, properties and uses. According to the standard level (see table), Class E glass fibers are widely used in electrical insulation materials; Class S is a special fiber, although its output is small, but it is very important, because of its super strength, it is mainly used for military defense, such as bullet-proof boxes; Class C is more chemically resistant than Class E, used for battery isolators and chemical filters; Class A is alkaline. Glass fibers are used to produce reinforced materials.

Glass for glass fiber is different from other glass products. The components of glass that have been commercialized internationally 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 fiberglass, which has good electrical insulation and mechanical properties. It is widely used in the production of fiberglass for electrical insulation, and also in the production of fiberglass for fiberglass reinforced plastics. Its shortcoming is that it is easy to be eroded by inorganic acids, so it is not suitable for acidic environment.

C-glass is also called medium alkali glass. Its chemical resistance is better than that of non-alkali glass, but its electrical performance is poor. Its mechanical strength is lower than that of non-alkali glass fibers by 10%-20%. Generally, foreign medium alkali glass fibers contain a certain amount of boron trioxide, while China's medium alkali glass fibers do 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. It is also used to reinforce asphalt roofing materials. But in China, medium alkali fiberglass accounts for more than half of the fiberglass output (60%). It is widely used to reinforce fiberglass as well as to reinforce asphalt roofing materials.