Aramid Fiber: Advantages & Applications in Ropes
- 1.Introduction
Aramid fiber, namely aromatic polyamide fiber, is a kind of high-performance synthetic fiber, which has excellent properties such as ultra-high strength, high modulus, high temperature resistance, light weight, anti-aging, long life cycle and so on. At the same time, it also has excellent dielectric properties, relatively stable chemical properties, insoluble in organic solvents and general concentrations of strong acids and bases, easy to bend, easy to process. Aramid fiber has stable chemical and mechanical properties, which makes it widely used in marine engineering, national defense research, aerospace, protection and rescue and other fields.
Aramid fiber is also very prominent in the field of rope due to its unique properties. For example, aramid fiber has high strength and strong impact absorption ability, which can be used to make parachute ropes for aerospace and support ropes for offshore oil fields; Aramid ropes are scour resistant and can be used for ship ropes, submarine cables, buoy system cables, etc. The advantages of aramid rope in weight reduction and easy storage and installation make it have the potential to replace steel cables and wire ropes; In terms of safety rescue, aramid fire rope has become a veritable "lifeline".
2.Construction
Like other high-performance fibers, aramid fibers have outstanding structure, that is, long-chain polymer molecules arranged parallel to the fiber axis. Unlike the entanglement of main chains in nylon molecules, the rigid benzene unit in Aramid solves the problem of chain arrangement when synthesizing fibers, and the main chain of aramid obtains higher main chain segments and orientation. The high parallel and highly oriented extended long chain structure determines that aramid fiber has good strength and high modulus.
The existence of hydrogen bonds in aramid fibers makes the interaction between chain molecules stronger and has good mechanical properties. The strength of aramid fiber is more than 3 times higher than that of ordinary organic synthetic fiber, while the modulus is more than 10 times that of nylon fiber and 9 times that of polyester fiber. However, due to the weak van der Waals force between hydrogen bonded crystal planes, the compressive strength of aramid fiber is weak.
3.Benefit
- Excellent mechanical properties
- Good chemical resistance
- Resistant to cutting and stabbing
- High thermal stability
- Low creep
- Flame retardancy
- Electrical insulation
- Long service life
4.Advantages of aramid fiber
- Mechanical properties
Aramid fiber is a high-performance fiber with ultra-high strength to weight ratio, which can play a good advantage in mechanical properties in a wide temperature range. At the same time, due to the high crystallization and high orientation of aramid,it also has relatively good tensile fatigue resistance, which makes aramid have a good service life. However, due to the weak transverse connection between aramid molecular chains, the bending fatigue resistance of aramid is much weaker. At the same time, the aramid fiber should be avoided from being exposed to sunlight for a long time, so as to avoid the decline of mechanical properties.
- Low creep behavior
Aramid fiber has low creep behavior, and even under continuous stress for a long time, the permanent deformation observed is very small. This is quite beneficial to the dimensional stability of aramid fiber when used. Moreover, aramid fiber has the characteristics of high modulus and negative thermal expansion coefficient, which further improves the dimensional stability of aramid fiber
- Heat resistance and flame retardancy
Aramid fiber has outstanding heat resistance and can be used in a very wide temperature range. Long term use at 200 ℃ will not affect the mechanical properties of aramid fiber. It will not shrink, soften or embrittle when exposed to 300 ℃ for a short time. At the same time, aramid fiber has excellent flame retardancy, is difficult to burn in the air, and has self extinguishing property. Therefore, aramid rope products have unique advantages in fire prevention and rescue applications
- Chemical resistance
The unique molecular
and crystal structure of aramid fiber, coupled with the closed form of its filaments,
can prevent chemicals from penetrating into the polymer structure of the
material, and can resist the corrosion of most highly concentrated inorganic
acids and other chemicals. Aramid products are suitable for most environments.