Introduction to ultra high Molecular Weight polyethylene (UHMWPE)

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Introduction to ultra high Molecular Weight polyethylene (UHMWPE)
Introduction to ultra high Molecular Weight polyethylene (UHMWPE)

Introduction to ultra high Molecular Weight polyethylene (UHMWPE)

Ultra high molecular weight polyethylene (UHMWPE) is a polyethylene with molecular weight between 1 million and 5 million. The molecular weight of ordinary polyethylene varies from hundreds of thousands to tens of thousands. Therefore, UHMWPE has the excellent characteristics that ordinary POLYETHYLENE cannot achieve, such as extremely high wear resistance, higher strength than most metals, and excellent impact resistance. Is a widely used engineering plastics.

At present, the world’s three high performance fibers are: aramid fiber, carbon fiber and UHMWPE fiber. Currently, aramid fiber is only produced in small quantities in China due to technical problems. Carbon fiber is still in the stage of testing and primary production, the product can only be used in the field of wear-resistant filler; Since the breakthrough of key production technology in 1994, uHMWPE fiber has formed several industrial production bases of UHMWPE fiber in China.

Merit:

1.lightweight :

UHMWPE has a density of only 0.97-0.98g/cm3 and can float on the water.

2.Excellent mechanical properties :

· The specific strength is more than 10 times that of steel wire of the same section
· The specific modulus is second only to super carbon fiber
· Low elongation at break, outstanding impact resistance and cutting resistance
· Extremely high wear resistance and self-lubricity
· The fatigue performance is the strongest among existing fibers and has a long service life

3.Water absorption is very low :

There is generally no need for drying before processing

4. Strong weatherability :

Has the excellent ultraviolet ray resistance ability, after 1500h sun, the intensity still preserves above 80%. It can screen radiation, so it can be used as a screen for nuclear power plants

5. Health non-toxic :

Can be used in contact with food and medicine

Defect :

Poor heat resistance :

The melting point of PE and ordinary PE is about 140℃.

High processing difficulty :

Uhmwpe has poor fluidity and a melt index of almost zero, requiring special equipment for processing.

Low stiffness and hardness :

But this shortcoming can be improved by modification

Application area :

01. National defense :

Due to its good impact resistance and higher energy absorption, the fiber can be made into protective clothing, helmets and bulletproof materials in the military, such as helicopter, tank and ship armor plate, radar protective housing, missile shield, bulletproof vest, stinger vest, shield, etc.

Among them, the application of flak jacket is the most eye-catching. It has the advantages of softness, bulletproof effect is better than aramid fiber, has become the main fiber occupying the Bulletproof vest market in the United States. In addition, the specific impact load of UHMWPE fiber composite is 10 times that of steel, and more than 2 times that of glass fiber and arylon fiber. Foreign bulletproof and riot helmets made of the fiber reinforced resin composite material have become substitutes for steel helmet and aramid reinforced composite material helmet.

02. Aviation :

In aerospace engineering, the fiber composite material is suitable for wing tip structure, spacecraft structure and buoy plane because of its light weight, high strength and good impact resistance.

The fiber can also be used as a deceleration parachute for space shuttle landings and as a rope to suspend heavy objects from the aircraft. Instead of traditional steel cables and synthetic fiber ropes, the fiber is developing very fast.

03. Civil aspects :

(1) Application of ropes and cables: Ropes, cables, sails and fishing gear made of the fiber are suitable for Marine engineering and are the initial uses of the fiber. It is commonly used for load line, heavy haul line, salvage line, towing line, sailboat line and fishing line.

The fiber rope, under its own weight, breaks eight times longer than steel rope and twice as long as arylon. This cable is used as anchor cable for supertankers, Marine operating platforms, lighthouses and so on, which solves the problems of corrosion, hydrolysis, and ultraviolet degradation caused by corrosion of steel cables and nylon and polyester cables in the past and requires frequent replacement.

(2) Sports equipment: In sports equipment, safety helmet, skis, sail board, fishing rod, rackets and bicycle, glide board, ultra-light aircraft parts have been made, and their wear resistance is better than traditional materials.

(3) Used as biomaterial: The fiber-reinforced composite material has been used for denture material, medical graft and orthopedic suture, etc. It has good biocompatibility and durability, high stability, and will not cause allergy, so it has been used in clinical application. It is also used for medical gloves and other medical measures.

(4) In industry, the fiber and its composite material can be used as pressure vessel, conveyor belt, filter material, automobile buffer plate, etc.; In terms of architecture, it can be used as wall and clapboard structure, etc. It can be used as reinforced cement composite material to improve the toughness and impact resistance of cement.