A. Performance characteristics of aramid fiber

1. Mechanical properties

The most significant characteristics of para-aramid are high strength and high modulus. Its strength is greater than 25 g/denier. It is 5 to 6 times that of high-quality steel, 3 times that of glass fiber, and 2 times that of high-strength nylon industrial yarn; its modulus is 2 to 3 times that of high-quality steel or glass fiber, and 10 times that of high-strength nylon industrial yarn; its toughness is 2 times that of steel wire times. In addition, aramid fiber is lightweight. Its weight is only about 1/5 of steel wire.

Performance comparison of para-aramid fiber and other high-strength fibers

2. Heat resistance

Aramid fiber has excellent thermal stability. Meta-aramid has almost no strength loss at 130°C. It can be used for more than ten years at 220℃. 100 hours at 260℃ high temperature. The mechanical strength remains 65% of the original. Carbonization begins around 400°C without melting. The heat resistance of para-aramid is better than that of meta-aramid. The shrinkage rate at 150°C is 0, and it does not decompose or melt at a high temperature of 560°C. The strength and modulus of nylon and polyester decrease as the temperature increases.

3. Flame retardant performance

Normally the oxygen content in air is 21%. The limiting oxygen index of meta-aramid fiber is greater than 28%. The limiting oxygen index of para-aramid fiber is about 30%. It is a flame retardant fiber. Therefore, it will not burn in the air, nor does it support combustion. It is self-extinguishing and does not produce molten droplets. When encountering extremely high temperatures, the fibers will rapidly expand and carbonize, forming a unique thermal insulation layer that can prevent external heat from entering the interior. Play an effective protective role. This inherent characteristic derived from its own molecular structure makes aramid permanently flame-retardant and has the reputation of "fire-proof fiber".

4. Chemical corrosion resistance

Aramid fiber has excellent chemical resistance. Usually only aramid fibers are exposed to relatively high concentration acid or alkali solutions for a long time. Will have a significant impact on the performance of aramid fiber. Also, aramid is not sensitive to mold or rust.

5. Electrical insulation

The electrical conductivity of aramid fiber is very low, and the fiber has poor hygroscopicity. It can maintain excellent electrical insulation properties in high and low temperature and high and low humidity environments. The breakdown voltage of insulating paper made of meta-aramid fiber can reach 100kV/mm. The resistance of para-aramid fiber reaches 5×1014Ω/cm. Due to excellent electrical insulation properties. It has good application prospects in the electronic and electrical fields.

In addition to the performance described above. Aramid cord also has good aging resistance, wear resistance and radiation resistance. As a class of high-performance materials. The excellent properties of aramid fiber have been developed and applied in different fields.

B. Market applications of aramid fiber

1. Military and defense fields

Aramid composite materials can be used to manufacture missile solid rocket motor casings, pressure vessels, spacecraft cockpits, submarines, bulletproof armored vehicles, bulletproof cash transport vehicles, bulletproof plates, bulletproof helmets, body armor, etc.

2. Security protection field

The flame-retardant and high-temperature resistance of personal protective equipment is an important condition for ensuring personnel safety. With the development of material science and technology and textile processing technology, flame-retardant protective clothing has gradually developed from temporary flame-retardant finishing and semi-durable flame-retardant finishing to durable flame-retardant finishing and the application of intrinsic flame-retardant materials.

3. Rubber reinforcement field

Because rubber has high elasticity and low elastic modulus, it is easily deformed under the action of external force. Therefore, many rubber products must use fiber materials or metal materials as the skeleton. Cord fabrics, cords, yarns, canvas, integral belt cores, straight warp and straight weft fabrics made of aramid are used as skeleton materials for tires, power transmission tapes, material conveying tapes, and hoses.

4. Environmental protection field

Aramid has excellent heat resistance, flame retardancy and chemical stability, and can work in high-temperature and harsh environments for a long time. It is an ideal material for processing high-temperature-resistant filter bags and is used in areas with heavy air pollution such as steel, cement, and carbon black. High temperature smoke and dust filtration.

Non-woven fabrics woven from meta-aramid fibers have very good dust filtering properties. For example, as a high-temperature filter cloth, meta-aramid non-woven fabrics with a density of 380 g/m2 have higher dust filtering properties than polyester cloths of 530 g/m2 and acrylic cloths of 600 g/m2. g/m2 better filtration properties. In the field of bag dust removal, meta-aramid filter bags have a service life of more than two years when the exhaust gas temperature does not exceed 200°C, the humidity is 6%, and the SO2 content is 100ppm.

5. Electronic and electrical materials field

(1) Antenna structural parts

(2) Special printed circuit substrate

(3) Aramid insulating paper

(4) Optical fiber

6. Aerospace field

Aramid can be used to make secondary structural materials for large aircraft, such as cabin doors, windows, wings, fairing surfaces, etc. It can also be used to make interior ceilings, warehouse walls, etc. to reduce their weight.

7. Sports equipment field

Make full use of the properties of aramid such as high temperature resistance and fatigue resistance to make boxing gloves, mountaineering boots, racing car bodies, horse racing helmets, etc. that have harsh sports conditions. It can also be used to make rackets, snowboards, ski poles, sleds, bows and arrows, bow strings, etc. Fishing rods, kite frames, golf clubs, rowing boats, etc.

8. Other fields

(1)Sealing material

(2) Rope

(3) Friction materials

(4) Building materials