Aramid fiber, referred to as "aramid fiber", is a new type of high-tech synthetic fiber. The production and research of aramid fiber in the United States, Japan, Europe and other countries are in a leading position. China's high-performance aramid technology enterprises have gone through many years. With the accumulation of R&D and technological breakthroughs, most of the aramid fibers produced in China have realized import substitution. Chinese aramid technology companies have taken a place in the international aramid fiber market. For example, YTTH Aramid Technology Group has realized the commercial production of high-performance aramid fibers, and the performance of the products has reached the level of similar products in the world.
Performance characteristics of aramid fiber
The main chain of aramid fiber is composed of aromatic ring and amide bond. The structure of aromatic ring has high rigidity, and the polymer chain is stretched to form a rod-like structure. At the same time, the molecular chain of linear structure makes the space utilization rate of aramid fiber high, so the unit volume can It contains more polymers and therefore higher strength. In addition, the conformation of the macromolecular chain is approximately linear, the cross-sectional area is small, the angular deformation of the macromolecular chain and the resistance within the bond are large, and the relative molecular mass is large.
Due to the difference in the microstructure of para-aramid fiber (PPTA) and meta-aramid fiber (PMIA) between para-position and meta-position, the physical properties are also different. Para-aramid fiber is obtained by polycondensation of terephthaloyl chloride and p-phenylenediamine. The molecular chain segments are relatively regular and the degree of orientation is high. The molecules are combined through hydrogen bonds to form hydrogen bonds and are stacked in the same direction to form fibers. Therefore, it has very strong rigidity, like rod-shaped molecules, good high temperature resistance, high strength, and high modulus body temperature. Utilizing the high orientation and easy fibrillation characteristics of para-aramid fiber, it can be made into aramid pulp to improve the adsorption force of the mixture, or used as reinforcing fiber to enhance friction and seal products.
Application of aramid fiber
Aramid fiber has excellent performance and is an important high-tech material in the material industry. It has the title of "omnipotent fiber". Aramid fiber and its products are widely used, mainly due to its high strength, high modulus, high temperature resistance and other characteristics.
Aramid fiber composite materials were originally used in rocket engine shells, aviation cylinders, aviation structural parts and military products. With the maturation of aramid fiber production technology and the reduction of costs, its applications have gradually expanded from aerospace and military fields to Civilian field.
Aerospace and military applications
Aramid fiber has high strength and certain corrosion resistance. It can be used in the manufacture of rocket engine shells, aircraft and spacecraft fuselages, main wings, and tail wings. As the requirements for aerospace materials become more and more demanding, aramid fibers have gradually developed from structural components that can withstand impact to secondary structural materials, such as cabin doors and windows, fairing body surfaces, and interior ceilings, partitions, bulkheads, luggage racks, Seats etc. In fact, the wide application of aramid fiber in aircraft is also inseparable from the light weight of aramid fiber. According to records, the weight of aircraft can be reduced by about 30% by using aramid fiber composite materials.
Civilian field
Conveyor belt, conveyor belt application
Miniaturization, light weight, and high efficiency are the development direction of modern mechanical transmission. As the application of belt transmission becomes more and more extensive, the requirements for belt transmission are getting higher and higher. For example, the automobile industry has proposed 240,000 km or 30 The rigorous requirements of 10,000 km even the same life span as automobiles have promoted the technological advancement of automobile transmission belts. Traditional road rubber has become increasingly unable to meet the current requirements for heat resistance of conveyor belts.
Construction sector
Aramid fiber composite materials are mainly used as reinforcement materials in the construction field. With aramid fiber reinforced cement, lightweight and high-strength structural parts can be obtained, which can effectively prevent the cracking of cement products. At the same time, the aramid fiber has good toughness and can be processed into cloth and cable. , Woven into a steel bar, as a cement-reinforced skeleton material, with light weight, high strength, corrosion resistance and shear resistance. Foreign research and development uses aramid fiber reinforced adhesive laminated wood beam technology, using low-grade wood instead of high-grade precious wood to greatly reduce the cost, the performance is not worse than the reinforced cement component and the cost is reduced. This technology has been researched and developed in European and American countries such as the United States, Germany, Japan, Australia and other countries, and has a broad application prospect.
Traffic field
Aramid fiber is mainly used in the transportation field to make tires for automobiles or airplanes. The tires made of aramid fiber are light and thin, have low rolling resistance and have good wear resistance; and the tires have high bearing capacity and are resistant to cutting and puncture; When working, the center of gravity moves small, the steering performance is good, the car is comfortable to ride; the heat dissipation is good, the tire is not easily deformed, and the tire has a long service life, which can meet the requirements of modern supersonic aircraft for tire use.
High temperature filter material
Meta-aramid fiber has good thermal stability and is difficult to age at high temperatures. It can be used for a long time at 220°C. It has good abrasion resistance and alkali resistance and slightly acid resistance. Various filter materials made of meta-aramid have been widely used in chemical plants, power plants, cement plants, lime plants, coking plants, as well as electric arc furnaces, oil boilers, incinerators and other high-temperature flue and hot air filtration to resist harmful The chemical corrosion of smoke not only effectively removes dust but also recovers precious metals.
Electronic and electrical field
Aramid fiber has high strength and can be used for fiber processing. When the fiber is under tension, it will not affect the transmission of light due to elongation and deformation; if the aramid fiber and carbon fiber are composite processed, it can be used to make materials that reduce the electric field in high-voltage devices; Utilizing the excellent wear-resistant and non-wearing surface characteristics of aramid chopped fibers, it can be used to make brakes (brakes), clutches, circuit breakers, etc. used in electronic and electrical equipment. It can also be used as an insulating material for heat-resistant motors in combination with natural mica flakes.
Other Applications
Aramid fiber materials can also be used in the manufacture of sports equipment, such as golf clubs, tennis rackets, skis, snowmobiles, and javelins. Hiking boots, boxing gloves, racing helmets, etc. with harsh sports conditions can also be made of aramid fiber.
The light weight of aramid fiber composite material can be used for shipbuilding, reducing the weight of the hull, saving fuel, and increasing the voyage. In addition, the aramid fiber composite material has strong ability to absorb vibration and endure continuous impact, and the ship sails stably, which improves the comfort of the boat. In addition, aramid fiber can also be used to make cables for sea ships and deep oil wells.
Prospects and development trends
Due to the limitation of foreign technology, the production and use of aramid fiber in China started relatively late. Since the industrialization of aramid fiber in 2004, the development of aramid fiber in China has changed rapidly. The production batch of aramid fiber in 2011 is the vane of domestic aramid fiber.
In order to fill the domestic consumption gap of aramid fiber and reduce the import volume, it is necessary to increase research and R&D, combined with enterprises and universities, to reduce the difficulty of aramid weaving and low processing efficiency, as well as strict requirements on the aerospace industry and materials. Claim. In other applications, the development of high-performance aramid fibers is an important future direction. In order to improve the adhesion between the surface of the aramid fiber and the substrate, and to improve the adhesion conditions between the aramid film and the substrate interface.
The development of aramid fiber is the key to the development of China's high-tech industry and the material basis for supporting the development of aerospace and military. However, compared with developed countries, China's aramid fiber research and development is seriously lagging behind, and many production equipment, raw materials and products are dependent on imports. Therefore, we must continue to work hard to break the international barriers of basic technology, independently break through technical barriers and innovations, realize the localization of aramid fiber, and go to the world.