Ultra high molecular weight polyethylene cable (UHMWPE, hereinafter referred to as PE), also known as "Dyneema", is just a material trademark name of DSM company. However, its reputation is very high, so this type of material is collectively referred to as "Dyneema" by many people. Most of the PE materials used in domestic equipment are not DSM products. This type of material has a mature production scale in China, and the quality of ultra-high molecular weight polyethylene cables in our country is already very good. Even Petzl often chooses cheaper domestic PE materials instead of dyneema products. Its color is generally pure white, with a small amount of high modulus polyethylene material in yellow/black.
Aramid rope, we often hear about Kevlar rope because its product trademark is "Kevlar Kevlar", which is a product of DuPont. There is also a similar material called "liquid crystal polymer" (LCP), which has similar properties to aramid. Their color is usually yellow.
Ultra high molecular weight polyethylene cables have high strength and good chemical resistance, and are commonly used in marine and mooring applications; Aramid ropes are resistant to high temperatures and are commonly used in the field of firefighting.
The above two materials are also commonly used in the manufacturing of bulletproof equipment due to their high strength. Of course, there are also many differences in their material properties, such as the low melting point of high modulus polyethylene, which is only around 145 degrees Celsius, but its specific gravity is lighter than water, so it can float on the water surface. And aramid can withstand high temperatures, with a carbonization temperature of around 450 degrees Celsius.
The difference in performance between ultra-high molecular weight polyethylene ropes and aramid ropes:
Density: Ultra high: 0.97 (can float in water); Aramid: 1.4
Scalability: Ultra high: Extremely low; Aramid: Extremely low.
Friction coefficient: ultra-high: very low; Aramid: Low.
Water absorption rate: ultra-high: very low; Aramid: Generally.
UV resistance: ultra-high: very good; Aramid: Not good.
Intensity: Ultra high: Very high; Aramid: Very high.
Melting point (℃): Ultra high: 145; Aramid: 450.
In the field of personal protective equipment, ropes made of ultra-high molecular weight polyethylene and aramid materials are mostly technical auxiliary ropes with diameters ranging from 5mm to 8.5mm. These auxiliary ropes have high strength but very low ductility, or can be blended to add some characteristics.
For ultra-high molecular weight polyethylene, the reason why this material is not suitable as a forward working rope is mainly due to its low melting point and low friction coefficient.
For aramid materials, there are indeed a small number of advanced work ropes made entirely of aramid on the market (due to their high temperature resistance, many are used in fire and police environments), and their ductility is also very low. However, aramid materials are too sensitive to ultraviolet radiation, and perhaps after two or three months of use, ultraviolet radiation can cause the rope skin to become powdery. Moreover, some aramid fibers are sensitive to frequent bending and prolonged deliquescence, which can also lead to a decrease in their strength.
In terms of ductility, ultra-high molecular weight polyethylene cables and aramid cables have extremely low ductility, which leads to a significant problem of decreased ability to absorb impact forces. The significant risk brought about during the process of exploring the cave is the enormous impact force generated by short distance operations or the failure of intermediate anchor points. So those low diameter ropes are not suitable for the vast majority of people and environments, and if widely used, they can easily cause accidents.
Moreover, the prices of ultra-high molecular weight polyethylene and aramid materials are much higher than nylon and polyester, so their cost-effectiveness as advanced work ropes is also very low.
Purchasing ultra-high molecular weight polyethylene ropes and aramid ropes, please feel free to contact us.