Glass fiber: it is a kind of inorganic nonmetal material with excellent performance. It has many advantages, such as good insulation, strong heat resistance, good corrosion resistance and high mechanical strength, but its disadvantage is brittle and poor wear resistance. It is made of glass ball or waste glass by high-temperature melting, drawing, winding, weaving and other processes. The diameter of single filament is from several microns to more than 20 meters, which is equivalent to 1/20 to 1/5 of a hair. Each bundle of glass fiber is composed of hundreds or even thousands of monofilaments. Glass fiber is usually used as reinforcement material in composite materials, electrical insulation material and thermal insulation material, circuit board and other fields of national economy.

Classification of glass fiber composite materials:

According to the shape and length of glass fiber, it can be divided into continuous fiber, fixed length fiber and glass wool;

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 glass fiber.

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 types of production methods for glass fiber:

One is to make the fused glass into fiber directly;

Another is to make glass balls or rods with a diameter of 20 mm, and then to produce very fine fibers with a diameter of 3-80 μm by heating and remelting in various ways. The infinitely long fiber drawn by mechanical drawing method through platinum alloy plate is called continuous glass fiber, generally known as long fiber. Through the roller or air flow made of discontinuous fiber, known as fixed length glass fiber, commonly known as short fiber.

Glass fibers are classified into different grades according to their composition, properties and uses. According to the standard, Grade E glass fiber is the most commonly used and widely used in electrical insulation materials; Grade S is special fiber.

There are many classification methods of glass fiber, which can be classified from the raw material composition, filament diameter, fiber appearance and fiber characteristics.

(1) It is generally distinguished by the content of alkali metal oxides.

Alkali free glass fiber (Grade E glass fiber)

Medium alkali glass fiber (Grade C glass fiber)

High alkali glass fiber (Grade A glass fiber)

(2) Classification by filament diameter

Glass fiber monofilament is cylindrical and can be divided into several types according to its diameter

Crude fiber: 30 μm;

Primary fiber: 20 μm;

Intermediate fiber: 10~20 μm;

Advanced fiber: 3~ 10 μm (also known as textile fiber);

Superfine fiber: the diameter of monofilament is less than 4 μm.

The different diameter of monofilament not only affects the properties of the fiber, but also affects the production process, output and cost of the fiber. Generally, 5-10 μm fibers are used for textile products; 10-14 μm fibers are suitable for roving, non-woven fabrics and chopped fiber felt.

(3) Classification by fiber properties

There are some new types of glass fiber with some special excellent properties, which is developed to meet the special requirements:

High strength glass fiber;

High modulus glass fiber;

High temperature resistant glass fiber;

Alkali resistant glass fiber;

Acid resistant glass fiber;

Ordinary glass fiber

Optical fiber;

Glass fiber with low permittivity;

Conductive fiber, etc

Features of glass fiber composites:

Compared with organic fiber, glass fiber has higher temperature resistance, non combustion, corrosion resistance, good heat insulation and sound insulation, high tensile strength and good electrical insulation. But it has brittle property and poor wear resistance. Glass fiber, which is used to make reinforced plastics or rubber, has the following characteristics. These characteristics make glass fiber more widely used than other kinds of fiber, and its development speed is far ahead:

(1) High tensile strength and small elongation.

(2) High elastic coefficient and good rigidity.

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

(4) It is an inorganic fiber with non flammability and good chemical resistance.

(5) Water absorption is small.

(6) The scale stability and heat resistance are good.

(7) It can be made into strand, bundle, felt, weaving and other different forms of products.

(8) Transparency can pass through light.

(9) The development of surface treatment agent with good adhesion to resin was completed.

(10) Fatigue resistance

(11) It is not easy to burn and can be melted into glass beads at high temperature