Four Major Types of High-Performance Organic Fiber Ropes

High-performance fiber ropes possess unique physical and chemical properties, playing a significant role in fields such as national defense, military industry, and aerospace, and are considered crucial strategic materials. Based on their chemical composition, high-performance fiber ropes can be categorized into inorganic and organic types. Compared to inorganic fibers represented by carbon fiber, organic fibers exhibit better wear resistance and weavability, making them the primary material for most ropes. High-performance organic fiber ropes mainly include aromatic fibers such as aramid, polyarylate, and polyimide, as well as olefin-based fibers represented by ultra-high molecular weight polyethylene (UHMWPE).

1. Aramid Ropes
Aramid, short for aromatic polyamide fiber, is highly notable for maintaining excellent mechanical properties even at high temperatures of up to 170 degrees Celsius. Aramid-reinforced composites are used in radar radomes, rocket fairings, and engine casings, effectively enhancing performance while reducing structural weight. However, the interfacial bonding strength between aramid and resin or rubber matrices needs improvement. Synergistic modification methods, such as plasma and bio-enzyme treatments, represent one of the key future development directions.

2. Polyarylate Fiber Ropes
Polyarylate fiber, fully known as liquid crystal polyarylate (LCP) fiber, is synthesized through the polycondensation of 4-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid. Compared to aramid, polyarylate fiber offers superior creep resistance and chemical stability. It has been used in the landing buffer airbags of the Spirit and Opportunity Mars rovers and the landing brake ropes of the Curiosity rover. In the future, it is expected to be applied in Mars exploration equipment such as Mars suits, inflatable landing decelerators, and habitats. However, polyarylate fiber exhibits significant performance degradation after ultraviolet exposure, limiting its application in space inflatable structures like stratospheric airships.

3. Ultra-High Molecular Weight Polyethylene Ropes
Ultra-high molecular weight polyethylene (UHMWPE) fiber is polymerized from ethylene monomers, with a relative molecular mass ranging from 3.5 million to 7.5 million. UHMWPE fiber has a density of only 0.97 g/cm³ and a specific strength of up to 370 cN/tex, making it the organic fiber with the highest specific strength currently available. UHMWPE fiber is commonly used in lightweight ballistic materials and marine ropes. However, due to the weak intermolecular forces, it is highly prone to deformation under high temperatures and external forces. Thus, creep modification of UHMWPE ropes has become a key research focus in recent years.

4. Polyimide Ropes
Polyimide (PI) fiber is primarily synthesized from two types of monomers: dianhydride and diamine. Its molecular structure contains a large number of aromatic groups connected by imide bonds, endowing it with exceptional thermal stability, radiation resistance, and dielectric insulation properties. Polyimide fiber is often used in lightweight thermal insulation materials, structural materials, and radiation protection materials for spacecraft. In recent years, with the development of high-strength and high-modulus PI fibers, their strength and modulus have surpassed those of aramid, demonstrating significant potential for application in load-bearing structures of spacecraft.

In summary, aramid ropes excel in high-temperature mechanical performance, making them suitable for high-temperature applications. Compared to aramid, polyarylate fiber offers superior creep resistance, making it ideal for long-term load conditions. UHMWPE ropes exhibit outstanding tensile strength but are highly sensitive to high temperatures and loads. Polyimide fiber stands out for its radiation resistance and thermal stability, making it an ideal alternative to aramid. The performance characteristics of these four high-performance organic fibers ensure their suitability for meeting the needs of fiber material selection in braided ropes.