Understanding and Applications of Aramid Fiber

What is aramid fiber?

Aramid fiber, also known as aromatic polyamide fiber, is a linear polymer composed of aromatic and amide groups. It has excellent mechanical properties, stable chemical structure, ideal mechanical properties, and outstanding performance such as high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight, and abrasion resistance.

Compared with ordinary flexible polymer molecules, the main chain structure of the para-aramid fiber is mainly composed of a rod-shaped molecular structure formed by benzene rings in the position. Due to the existence of large conjugated benzene rings, the molecular chain segments are difficult to undergo internal rotation, presenting a linear rigid structure.

The main chain of aramid fiber molecules has good regularity and contains rigid crystal units, which can easily form a liquid crystal state. When this rigid molecular chain is in the liquid crystal state, it can be arranged in parallel with an increase in concentration. The internal molecular chain segments have high order without special stretching, and can achieve an extended chain structure only through spinning orientation, achieving a high modulus.

Moreover, in the spinning process, this structure can also stack multiple layers of high-density orientation along the fiber axis in a limited space, making the polymer have high strength. The molecular chains of aramid fibers are highly oriented along the fiber axis, and hydrogen atoms on the amide groups can form hydrogen bonds with carbonyls on another molecular chain to form hydrogen bond cross-linking between molecular chains. Aramid fibers include different forms of supramolecular structures such as skin-core, subcrystal, and microfiber structures.

Applications of aramid vs carbon fibers

Aramid vs carbon fibers are widely used in various fields. Carbon fibers are generally not used alone but are often combined with resins, metals, ceramics, and other materials to form carbon fiber composites. They can be used in unmanned aerial vehicles, aircraft, mechanical arms, rail vehicles, CT boards, and sports equipment. Aramid fibers can be used in the form of UD, fabric, winding, etc., and have good adhesion with rubber. They are suitable for making wideband transparent materials and large rigid sub-stressed structural components (such as wings, fairings, cabin liners, cabin doors, floors, cargo compartments, and bulkheads) for aircraft, missiles, and satellites, as well as sandwich structures for yachts, sculls, high-speed trains, and other high-performance structures. Both aramid and carbon fibers have excellent mechanical properties and can be used in combination to form sandwich structures with lighter weight and better strength.