The development of aramid fibers

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Aramid fiber, whose full name is “poly(p-phenylene terephthalamide)”, is also known as Aramid fiber; DuPont’s brand name for it is Kevlar. It is a type of advanced synthetic fiber that boasts excellent properties such as ultra-high strength, high modulus, resistance to high temperatures, acids, and alkalis, as well as low weight. Its strength is 5 to 6 times that of steel wire, its modulus is 2 to 3 times that of steel wire or glass fiber, and its toughness is twice that of steel wire. Meanwhile, its weight is only about 1/5 of that of steel wire. It does not decompose or melt at temperatures of 560 degrees Celsius. It has good insulation and aging resistance, as well as a long service life. The discovery of aramid is considered a very important historical milestone in the field of materials science. 　　Aramid fibers are important materials for defense and military applications. To meet the demands of modern warfare, bulletproof vests in developed countries such as the United States and the United Kingdom are now made of aramid material. The lighter weight of aramid-based bulletproof vests and helmets enhances the rapid response capabilities and combat effectiveness of military forces. During the Gulf War, American and French aircraft made extensive use of aramid composite materials. In addition to its applications in **, it is now used as a high-tech fiber material across various sectors of the national economy, including aerospace, mechanical and electrical engineering, construction, automotive industry, and sports equipment. In the fields of aviation and aerospace, aramids, with their low weight and high strength, help to save a significant amount of fuel. According to foreign sources, during the launch of spacecraft, reducing the weight by just 1 kilogram can result in cost savings of $1 million. In addition, the rapid advancement of technology is opening up more new civilian applications for aramid. It is reported that currently, aramid products are used in bulletproof vests, helmets, etc. in about 7–8%, while they are used in aerospace materials and sports materials in roughly 40% ； Materials for tire skeletons and conveyor belts account for about 20%, while high-strength ropes and similar materials account for around 13%. 　　Aramid fibers are mainly divided into two types: para-aramid fibers (PPTA) and meta-aramid fibers (PMIA). Since DuPont in the United States successfully developed aramid fibers and brought them to commercial use in the 1960s, over the course of more than 30 years these fibers have evolved from being strategic materials for military use to materials for civilian applications, with their prices dropping by nearly half. Currently, the research and development as well as large-scale production of aramids abroad are becoming increasingly mature. In the field of aramid fiber production, para-aramid fibers have seen the fastest development, with production capacity primarily concentrated in Japan, the United States, and Europe. Such as DuPont’s Kevlar fiber in the United States, Twaron fiber from Akzo Nobel in the Netherlands (which has merged with Teijin), Technora fiber from Teijin in Japan, and Terlon fiber from Russia. Examples of meta-aramid fibers include Nomex, Conex, Fenelon fiber, etc. DuPont in the United States is a pioneer in the development of aramids. It is at the world’s leading level in terms of new product development, production scale, and market share. The Kevlar fibers produced by this company include more than a dozen different grades such as Kevlar-49 and Kevlar-29, with each grade offering dozens of different variants. DuPont announced last year that it would expand the production capacity of Kevlar fibers, with the expansion project expected to be completed by the end of this year. Well-known companies in the aramid production sector, such as Teijin and Hearst, are also not willing to fall behind; they are expanding their production capacities or forming partnerships, and actively exploring new markets in an effort to become key players in this emerging industry. 　　The German company Acordis has recently developed high-performance ultra-fine para-aramid (Twaron) products. These materials are non-flammable and do not melt; they also possess high strength and excellent resistance to cutting. They can be used to produce coated and uncoated fabrics, knitted products, and needle-punched felts – all of which are suitable for use in textile and clothing applications that require resistance to high temperatures and cutting forces. The fineness of Twaron ultra-fine filaments is only 60% that of para-aramid, which is commonly used in protective clothing; gloves woven from it have a 10% improved cut resistance. When used to produce woven and knitted products, it yields a softer feel and greater comfort. Twaron cut-resistant gloves are primarily used in the automotive industry, glass manufacturing, and metal parts production plants. They can also be used to produce protective leg gear for the forestry industry, as well as anti-vandalism equipment for the public transportation sector. Leveraging Twaron’s flame-retardant and heat-resistant properties, it can be used to manufacture protective suits and blankets for fire departments, as well as heat- and flame-resistant clothing for industries involving high temperatures such as foundries, furnaces, and glass factories; it can also be used to produce flame-retardant and fire-resistant coating materials for airplane seats. This high-performance fiber can also be used to create components such as automobile tires, cooling hoses, and V-belts, as well as protective equipment like optical fiber cables and bulletproof vests. It can also replace asbestos as a friction material and sealing material. 　　According to statistics from relevant authorities, the world’s total demand for aramid fibers was 360,000 tons per year in 2001, and it was expected to reach 500,000 tons per year by 2005. Global demand for aramid is on the rise, and as an emerging high-performance fiber, aramid is entering a period of rapid development. 　　In contrast to the booming overseas aramid fiber industry, the localization of aramid fibers has only just begun. Due to the late start of the development of aramid fibers in China, as well as foreign companies’ monopoly over key technologies, China’s current technical level, product quality, and production capacity in this field still fall short compared to those of developed countries abroad. It is reported that in recent years, the electronics, construction, and tire industries in our country have developed rapidly, leading to a sharp increase in the consumption of aramids in our country. There are mainly two reasons why it is so difficult to achieve domestic production of aramids in our country: first, the technical barriers to production are hard to overcome ； Second, most of the raw materials need to be imported, especially as domestic solvents cannot pass inspection. But it is precisely because it is a new phenomenon in the domestic market and the market is still far from saturated that it deserves our attention and development efforts. At present, the development of aramid production in our country has been put on the agenda; aramid is included in the **list of high-tech products whose development is encouraged**, and the development of technologies for using aramid fibers in engineering tires and synchronous belts has also been designated as a key research and industrialization project for China’s rubber industry during the 10th Five-Year Plan period. In particular, China has made certain progress in the development and production of aromatic amides in its meta-production lines.