As a key strategic new material, high-performance fiber is a hot spot in the industry. Zhan Xinjun previously analyzed carbon fiber, which is a representative of inorganic fibers in high-performance fibers. Today we analyze the representative of organic high-performance fibers-aramid.
From police to soldiers, from athletes to astronauts, from emergency responders to industrial workers, there are aramid credits in special clothing, bulletproof jackets, helmets, protective gloves, buffer protective layers outside transmission fiber, and mobile phones, tires, and high Aramid is widely used in performance sportswear and equipment.
Aramid: the pearl in high-performance fiber materials
The full name of the aramid fiber is an aromatic polyamide fiber, which refers to a long-chain synthetic polyamide fiber in which more than 85% of amide bonds are directly connected to a benzene ring. Aramid was born in the 1960s. It was developed by the United States DuPont Company and took the lead in industrialization. It is a new type of special purpose synthetic fiber, and it is also the main category of organic high temperature resistant fibers.
Aramid fibers have high strength, high modulus, and light weight mechanical properties. The tensile strength is 3.0 to 5.5 GPa, the elastic modulus is 80 to 160 GPa, and the elongation at break is about 3%. Therefore, it is often used as a reinforcing material in applications In composite materials. From the perspective of functional characteristics, aramid fiber has high temperature resistance, chemical resistance, high dimensional stability, excellent insulation and aging resistance. According to different molecular structures, aramid is mainly divided into three types of ortho-aramid, meta-aramid, and para-aramid. At present, industrialized aramids are mainly two types of meta-aramid (Aramid 1313, PMIA) and para-aramid (Aramid 1414, PPTA).
Both are aramid fibers with excellent mechanical properties, but para-aramid and meta-aramid have their own characteristics. Para-aramid is a rigid polymer material arranged in para-position. Its outstanding features are high strength, high dimensional stability, and low density. The strength of para-aramid is 3 times that of steel, and the density is only 1/5 of that of steel; the stability is good, and the shrinkage is 0 at 150 ° C. Therefore, para-aramid is mainly used in high weight reduction and high performance fields, such as aerospace, bullet-proof weapons and equipment, automotive industry, shipbuilding industry, sports equipment and so on.
The meta-aramid's macromolecular chain is zigzag-shaped, and its fire resistance and oxidation resistance dominate. After continuous use at 250 ° C for 1000 hours, its strength can still maintain 65% of its original strength. Therefore, meta-aramid is often used as an organic high-temperature-resistant fiber and is applied in the fields of high-temperature protective clothing, flame-retardant fabrics for aircraft insulation, and the like.