What is UHMWPE?
UHMWPE (ultra-high molecular weight polyethylene) generally refers to polyethylene products with a relative molecular weight of more than 1.5 million.
Molecular composition structure
UHMWPE macromolecules are mainly composed of methylene. The molecular chain basically does not contain polar groups. And there are no branched chains and double bonds in the molecular structure.
What are the mechanical behaviors of UHMWPE?
UHMWPE has superior mechanical behaviors that other kinds of conventional molecular weight polyethylene do not have. Due to its many excellent properties, it is called “strange plastic”. The abrasion resistance of UHMWPE ranks first among plastics, which is several times higher than that of carbon steel and brass. Its abrasion resistance is more than ten times higher than that of ordinary polyethylene. And it will be further improved with the increase of molecular weight. The friction coefficient of UHMWPE is smaller than other engineering plastics and can be comparable with PTFE. So UHMWPE is an ideal lubricating material. Its water absorptionis the smallest in engineering plastics. It has the highest impact resistance among engineering plastics, even 3 – 5 times higher than polycarbonate, which is famous for its impact resistance. Because its molecular structure is mainly linear, its tensile strength is as high as 3 – 3.5 gpa and its tensile elastic modulus is up to 100 – 125 gpa. In addition, UHMWPE also has excellent chemical resistance and can resist various corrosive media and organic solvents in a certain temperature and concentration range.
Application and development prospect
At present, many UHMWPE high-end products can be used for military purposes and high-tech fields. Because UHMWPE has many excellent characteristics, it shows great advantages in the high-performance fiber market, including mooring lines in offshore oil fields and High-Performance Lightweight composites. It plays an important role in modern war, aviation, aerospace, marine defense equipment and other fields.
♦UHMWPE can be used to build the lining of the bucket, silo and chute for loading coal, lime, cement, mineral powder, salt, grain and other powdery objects. Because it has excellent self-lubricating and non viscosity, the above powdery objects will not adhere to the storage and transportation facilities and ensure stable preservation.
♦UHMWPE is used to make liquid storage pipes such as quicksand. The barrier in the tube is 25% smaller than that in the non-metallic tube. Compared with bamboo tube, its longevity is increased by 18 times and its interest rate is reduced to 1 / 25; Compared with nylon tube, the service life is increased by 3 times and the interest is reduced to 1 / 8.
♦In the range of chute, bucket and ore cabin lining, when using traditional non-metallic documents, in cold and humid weather, the articles will thaw on the non-metallic, while the adoption of UHMWPE plate will never happen, which greatly reduces the unloading cost. After lining a layer of UHMWPE plate on the self unloading leakage of bulk vehicles and ships, the symmetrical unloading time is reduced from 16 – 20 hours to 8 hours.
♦In terms of national defense and quartermaster equipment, due to UHMWPE’s good impact resistance and large specific energy absorption, it can be made into protective clothing materials, helmets and bulletproof materials in military, such as armored protective plates of helicopters, tanks and ships, protective shell covers of radar, missile covers, bulletproof clothing, stab proof clothing, shields, parachutes, etc.
♦In aerospace engineering, because of UHMWPE’s light weight, high strength and good impact resistance, it is suitable for wing tip structure, spacecraft structure and buoy aircraft of various aircraft. At the same time, it can also be used as a deceleration parachute for the landing of the space shuttle and a rope for suspending heavy objects on the aircraft, replacing the traditional steel rope and synthetic fiber rope. The development speed in this area is extremely rapid.
♦In the civil field, the ropes, cables, sails and fishing gear made of UHMWPE are suitable for marine engineering. The breaking length under self weight is 8 times that of steel rope and 2 times that of aramid fiber. The UHMWPE rope is used for the fixed anchor rope of super oil tanker, marine operation platform, lighthouse, etc. It solves the problems of corrosion encountered in the past and corrosion, hydrolysis and UV degradation encountered in nylon and polyester cables, which cause the cable strength to decrease and fracture and need to be replaced frequently.
♦In industrial application, UHMWPE can be used in pressure vessel, conveyor belt, filter material, automobile buffer plate, etc. In architecture, it can be used as wall and partition structure. Using it as reinforced cement composite material can improve the toughness and impact resistance of cement. Because of its excellent abrasion resistance and impact resistance, it is widely used in the machinery manufacturing industry. It can make many kinds of mechanical parts such as gears, cams, impellers, rollers, pulleys, bearings, bearing shells, bearing sleeves, shaft cutting, gaskets, gaskets, elastic couplings, screws and so on.
♦In sporting, UHMWPE has been used to make safety helmets, skis, sail wheels, fishing rods, rackets, bicycles, gliders, ultra light aircraft parts and so on. Its performance is better than traditional materials.
♦In medicine, UHMWPE is used in the fields of dental support materials, medical grafts and plastic sutures. It has good biocompatibility and durability, high stability and will not cause allergy. It has been used in clinical application. It is also used in medical gloves and other medical measures.