The development status of aramid and its surface modification research progress
The development status of aramid and its surface modification research progress
Aramid is a high-performance synthetic fiber prepared by spinning aromatic polyamide resin. Its macromolecular main chain is a long chain structure composed of amide bonds and aromatic rings alternately connected. Its full name is ” Aramid fiber”, the English name is “aramidfiber”. Aramid products come in various forms, including aramid filament, chopped fiber, pulp, aramid paper, aramid cloth, aramid composite materials, etc. Aramid has Low density, high modulus, high strength, cutting resistance, corrosion resistance, high temperature resistance, insulation and flame retardant and other excellent properties, it is widely used in aerospace, military industry and defense, transportation, electronic communications, tire rubber, safety protection, sports and leisure Environmental protection and other fields. Aramid is an important strategic material for national defense construction and economic development. Developed countries in the world attach great importance to the research and utilization of aramid.
The molecular chain segments of aramid fiber are highly regular and there are few active groups on the surface of the fiber, resulting in strong hydrophobicity and poor surface wettability of the aramid fiber. At the same time, the fiber has high crystallinity and smooth surface, resulting in weak interfacial bonding force and affecting the relationship between it and the matrix. The bonding properties of aramid. The molecular chain of aramid contains a large number of benzene ring rod-like molecular structures, which can form liquid crystals. The spinning process can make the fiber molecules highly oriented and stretched along the axial direction and achieve high-density stacking, thus having a relatively high axial modulus. However, the fibers are connected laterally by hydrogen bonds and intermolecular forces, and their mechanical properties are low. Fibers are easily broken under shear or compression force. When the fiber surface is damaged, its mechanical properties drop significantly. Fast, especially for aramid with skin-core structure.
In order to promote the combination of aramid fiber and the matrix interface, improve the mechanical properties of composite materials, and realize its high value-added utilization, the surface modification and functionalization research of aramid fiber has increasingly become the focus and difficulty of research. This article introduces the characteristics of aramid fiber The development process summarizes the classification and properties of aramid fiber, and elaborates on the main methods of surface modification and functionalization of aramid fiber as well as the latest research results. It is hoped to provide new ideas for subsequent research on aramid fiber and develop economical, green and Efficient modification method to prepare high-performance aramid products.
1
The development history and current situation of aramid fiber
Aramid was little known as a strategic material and space material at first. With economic development and social progress, it has been widely used in various fields because of its excellent properties. DuPont in the United States has done a lot of research on the development and application of aramid. Made great contributions: In the middle of the 20th century, DuPont’s research on low-temperature solution polymerization methods and the dissolution process of insoluble polymers laid the foundation for the birth of aramid; in 1967, DuPont commercialized the first high heat-resistant meta Aramid, the registered trademark is Nomex®; in 1972, para-aramid with better mechanical properties was launched, with the trade name Kevlar®. Since then, countries around the world have successively launched their own aramid products. In 1972, Teijin Corporation of Japan began commercial The company chemically produced meta-aramid Conex®, followed by the para-aramid Technora® in 1978. The Dutch company AkzoNobel developed the para-aramid Twaron® in 1986 and was sold by Japan in 2000. Acquired by Teijin Corporation. At the same time, Russia’s Armos® ternary copolymer para-heterocyclic aramid, SVM® binary heterocyclic aramid and Terlon® para-aramid also came out one after another. The development of aramid in my country lagged behind until the 1980s. Trial production of aramid 14 and aramid 1414 began in the mid-1990s. Yantai Taihe New Material Company mass-produced meta-aramid in 2004. Subsequently, South Korea’s Kolon Group put into production para-aramid Heracron® in 2006. Star Group put into production the para-aramid fiber ALKEX® in 2009, and Cathay New Materials launched the para-aramid fiber Taparan® in 2011.
According to reports, in 2018, the global production capacity of meta-aramid fiber was 39,000 tons, 50% of which was produced by DuPont. The global annual demand was 40,000 tons, mainly distributed in developed countries such as the United States and Europe; my country’s effective annual production capacity of meta-aramid fiber It is about 10,000 tons, the demand is about 6,000 tons, and most of the rest is exported. The global production capacity of para-aramid fiber is about 76,000 tons, mainly produced by DuPont and Teijin, and the global annual demand is 70,000 to 80,000 tons. ; my country’s effective annual production capacity of para-aramid fiber is 2,000 tons, but the demand is as high as 10,000 tons. The overall market gap is large, and a large amount of imports are still needed. Because aramid fiber involves sensitive fields such as military industry, national defense, aerospace and aviation, foreign developed countries have long-term Strictly block the production of raw materials, products, etc.Font, Arial, Helvetica, sans-serif;font-size:14px;”>
Summary and outlook
With its excellent performance, aramid fiber has important applications in traditional fields such as national defense and military industry, and also shows great potential in emerging fields such as new energy vehicles and 5G communications. my country’s aramid fiber industry started relatively late, but in recent years it has also It has made great progress, but there is still a certain gap between the international leading level. In comparison, my country’s aramid fiber needs to be improved in terms of output, quality, and product types, and product application areas also need to shift from the low-end market to the high-end market. The research on the modification of aramid fiber is the basis for realizing the wide application of its products. At present, traditional chemical, physical and other modification methods are also constantly developing. With the advancement of science and technology and the deepening of research, the surface modification method of aramid fiber will become more economical and environmentally friendly. ､With the trend of high-efficiency continuous, combined and joint modification of multiple processing methods, it is foreseeable that more multi-functional aramid products with a wider range of applications will be developed in the future.
