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Encyclopedia > Ultra high molecular weight polyethylene

Ultra high molecular weight polyethylene (UHMWPE), also known as high modulus polyethylene (HMPE) or high performance polyethylene (HPPE), is a thermoplastic. It has extremely long chains, with molecular weight numbering in the millions, usually between 2 and 6 million. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made. It is highly resistant to corrosive chemicals, with exception of oxidising acids. It has extremely low moisture absorption, very low coefficient of friction, is self lubricating and is highly resistant to abrasion (15 times more resistant to abrasion than carbon steel). Its coefficient of friction is significantly lower than that of nylon and acetal, and is comparable to teflon, but UHMWPE has better abrasion resistance than teflon. It is odorless, tasteless, and nontoxic. This article does not cite any references or sources. ... A thermoplastic is a material that is plastic or deformable, melts to a liquid when heated and freezes to a brittle, glassy state when cooled sufficiently. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... The resistance to lateral motion when one attempts to slide the surface of one object over another surface is called friction or traction. ... Abrasion may mean: Abrasion (medical), superficial damage to the skin, generally not deeper than the epidermis Abrasion (dental), the loss of tooth structure by mechanical forces from a foreign element Abrasion (geology) (corrasion), mechanical scraping of a rock surface by friction between rocks and moving particles during their transport in... Carbon steel, also called plain carbon steel, is a metal alloy, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. ... Nylon is a generic designation for a family of synthetic polymers first produced on February 28, 1935 by Wallace Carothers at DuPont. ... It has been suggested that Delrin be merged into this article or section. ... Teflon is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene. ...


Polymerisation of UHMWPE was commercialised in the 1950s by Ruhrchemie AG, which changed names over the years; today UHMWPE powder materials are produced by Ticona. UHMWPE is available commercially either as consolidated forms, such as sheets or rods, and as fibers. UHMWPE powder may also be directly molded into the final shape of a product. Because of its resistance to wear and impact, UHMWPE continues to find increasing industrial applications, including the automotive and bottling sectors, for example. Since the 1960s, UHMWPE has also been the material of choice for total joint arthroplasty in orthopedic and spine implants [2]. Ticona is an international manufacturer of engineering polymers. ... Arthroplasty (literally formation of joint) is an operative procedure of orthopaedic surgery performed for replacing the arthritic or dysfunctional joint surface with something better or remodeling or realigning the joint by osteotomy or some other procedures. ... Orthopedic surgery or orthopedics (BE: orthopaedics) is the branch of surgery concerned with acute, chronic, traumatic and recurrent injuries and other disorders of the locomotor system, its musclular and bone parts. ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ...


UHMWPE fibers, commercialised in the late 1970s by the Dutch chemicals company DSM, are widely used in ballistic protection, defense applications, and increasingly in medical devices as well. DSM (in full Koninklijke DSM N.V., or Royal DSM N.V.) is a multinational chemicals company. ...

Contents

Overview

Structure and properties

Structure of UHMWPE, with n greater than 100,000
Structure of UHMWPE, with n greater than 100,000

UHMWPE is a type of polyolefin and, despite relatively weak Van der Waals bonds between its molecules, derives ample strength from the length of each individual molecule. It is made up of extremely long chains of polyethylene, which all align in the same direction. Each chain is bonded to the others with so many Van der Waals bonds that the whole can support great tensile loads. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... A polyolefin is a polymer produced from a simple olefin, or alkene as a monomer. ... Van der Waals bonding, also known as London force, instantaneous dipole effect, and induced dipole interaction, is an intermolecular force or interatomic force that causes an attraction between temporarily induced dipoles in nonpolar molecules and atoms. ... This article does not cite any references or sources. ... Tensile stress (or tension) is the stress state leading to expansion; that is, the length of a material tends to increase in the tensile direction. ...


When formed to fibers, the polymer chains can attain a parallel orientation greater than 95% and a level of crystallinity of up to 85%. In contrast, Kevlar derives its strength from strong bonding between relatively short molecules. Chemical structure of Kevlar. ...


The weak bonding between olefin molecules allows local thermal excitations to disrupt the crystalline order of a given chain piece-by-piece, giving it much poorer heat resistance than other high-strength fibers. Its melting point is around 144 to 152 degrees Celsius, and according to DSM, it is not advisable to use UHMWPE fibers at temperatures exceeding 80 to 100°C for long periods of time. It becomes brittle at temperatures below -150°C. The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... A material is brittle if it is subject to fracture when subjected to stress i. ...


The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the polar groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, but it also does not get wet easily, which makes bonding it to other polymers difficult. For the same reasons, skin does not interact with it strongly, making the UHMWPE fiber surface feel slippery. Similarly, aromatic polymers are often susceptible to aromatic solvents due to aromatic stacking interactions, an effect aliphatic polymers like Dyneema are also immune to. Since Dyneema does not contain chemical groups (such as esters, amides or hydroxylic groups) that are susceptible to attack from aggressive agents, it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms. A commonly-used example of a polar compound is water (H2O). ... Wetting of different fluids. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Aromatic stacking interaction, sometimes called phenyl stacking, is a phenomenon in organic chemistry that affects aromatic compounds and functional groups. ... In chemistry, non-aromatic and non-cyclic (acyclic) organic compounds are called aliphatic. ... A carboxylic acid ester. ... Amide functional group Amides possess a conjugated system spread over the O, C and N atoms, consisting of molecular orbitals occupied by delocalized electrons. ... // Hydroxyl group The term hydroxyl group is used to describe the functional group -OH when it is a substituent in an organic compound. ...


Under tensile load, UHMWPE will deform continually as long as the stress is present - an effect called creep. Creep is the term used to describe the tendency of a material to move or to deform permanently to relieve stresses. ...


Annealing

To anneal UHMWPE the material should be heated to 135 °C to 138 °C in an oven or a liquid bath of silicone oil or glycerine. The material must then be cooled down at a rate of 5 °C / hour to at least 65 °C. Finally the material should be wrapped in an insulating blanket for 24 hours to bring to room temperature.[1] The word anneal has several meanings: In metallurgy and materials science annealing is a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. ... Silicone oils (polymerized siloxanes) are silicon analogues of carbon based organic compounds, and can form (relatively) long and complex molecules based on silicon rather than carbon. ... Glycerin, also known as glycerine and glycerol, and less commonly as 1,2,3-propanetriol, 1,2,3-trihydroxypropane, glyceritol, and glycyl alcohol is a colorless, odorless, hygroscopic, and sweet tasting viscous liquid. ...


Production

UHMWPE is synthesized from monomers of ethylene, which are bonded together to form what is called ultra high molecular weight polyethylene (or UHMWPE). These are molecules of polyethylene which are several orders of magnitude longer than familiar high density polyethylene due to a synthesis process based on metallocene catalysts. HDPE molecules generally have between 700 and 1,800 monomer units per molecule, while UHMWPE molecules tend to have 100,000 to 250,000 monomers each. Synthesis (from the Greek words syn = plus and thesis = position) is commonly understood to be an integration of two or more pre-existing elements which results in a new creation. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... Ethylene (or IUPAC name ethene) is the chemical compound with the formula C2H4. ... This article does not cite any references or sources. ... An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. ... HDPE has SPI resin ID code 2 High-density polyethylene (HDPE) is a polyethylene thermoplastic made from petroleum. ... In chemistry, and in particular, in organometallic chemistry, a metallocene is a compound consisting of an aromatic organic ligand bound to a metal. ... A Kaminsky catalyst is a catalytic system for olefin polymerization discovered by Walter Kaminsky and coworkers in 1980. ...


Finished UHMWPE is produced by 4 major methods: compression molding, ram extrusion, gel spinning, and sintering. The leading manufacturers of each process UHMWPE in different ways:


compression molding (PPD, Hutchinson, NorthAmerican) ram extrusion and fabrication (Garland Manufacturing, Artek) gel spinning - armor and cordage (Dyneema) sintering - Medical (Quadrant, Solus, Perplas)


Dyneema fibers are made using a DSM patented (1979) method called gel spinning. A precisely heated gel of UHMWPE is processed by an extruder through a spinneret. The extrudate is drawn through the air and then cooled in a water bath. The end result is a fiber with a high degree of molecular orientation, and therefore exceptional tensile strength. Gel spinning depends on isolating individual chain molecules in the solvent so that intermolecular entanglements are minimal. Entanglements make chain orientation more difficult, and lower the strength of the final product. Extrusion is a manufacturing process where a billet of material is pushed and/or drawn though a die to create a shaped rod, rail or pipe. ... A spinneret is a spiders silk spinning organ. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... Entanglement can refer to the process which results in felt from fibers and dust bunnies from hairs etc. ...


Capacity

Production capacity of DSM Dyneema is about 5000-6000 tons/yr by 2008 as the 10th production line will be finished in 2008[2], [3]. 5 lines are located in Heerlen, The Netherlands and 5 in Greenville, North Carolina (USA). Heerlen ( (help· info)) is a municipality and a town in the southeastern Netherlands and the fourth largest municipality in the province of Limburg. ... Motto: Je Maintiendrai (Dutch: Ik zal handhaven, English: I Shall Uphold) Anthem: Wilhelmus van Nassouwe Capital Amsterdam1 Largest city Amsterdam Official language(s) Dutch2 Government Parliamentary democracy Constitutional monarchy  - Queen Beatrix  - Prime minister Jan Peter Balkenende Independence Eighty Years War   - Declared July 26, 1581   - Recognised January 30, 1648 (by Spain... Nickname: Pro Town USA Location of Greenville shown within North Carolina Coordinates: Country United States State North Carolina County Pitt County Settled 1771 Founded 1774 (Martinsborough) Founded 1786 (Greenville) Mayor Don Parrott Area    - City 68 km²  (26. ...


Trade Names

Dyneema is a registered trademark of Royal DSM N.V. (The Netherlands). Dyneema was invented by DSM in 1979. It has been in commercial production since 1990 at a plant in Heerlen, the Netherlands. In the Far East, DSM has a cooperation agreement with Toyobo Co. for commercial production in Japan. In the United States, DSM has a production facility in Greenville, North Carolina which is the largest production facility in the United States for UHMWPE fiber. DSM (in full Koninklijke DSM N.V., or Royal DSM N.V.) is a multinational chemicals company. ... Also: 1979 by Smashing Pumpkins. ... Year 1990 (MCMXC) was a common year starting on Monday (link displays the 1990 Gregorian calendar). ... Heerlen ( (help· info)) is a municipality and a town in the southeastern Netherlands and the fourth largest municipality in the province of Limburg. ... East Asia Geographic East Asia. ...


Honeywell developed a chemically identical product, which is sold under the brand name Spectra. Though the production details are somewhat different, the resulting materials are comparable in properties.


Other trade names for consolidated UHMWPE materials include TIVAR by Poly Hi Solidur, and Polystone-M by Rochling Engineered Plastics.


Usage

Fiber applications

Dyneema and Spectra are gel spun through a spinneret to form oriented-strand synthetic fibers of UHMWPE which have yield strengths as high as 2.4 GPa and density as low as 0.97 Kg/l (for Dyneema SK75)[4]. This gives a strength/weight ratio as much as 15 times stronger than steel [citation needed] and up to 40% stronger than Aramid. A spinneret is a spiders silk spinning organ. ... Synthetic fibers are the result of extensive research by scientists to increase and improve upon the supply of naturally occurring animal and plant fibers that have been used in making cloth and rope. ... The initials GPA can refer, among other things, to Grade Point Average; see Grade (education) Guinness Peat Aviation General Practice Australia, a private, independent medical accreditation society Greyhound Pets of America This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same... KG, kg or Kg can refer to several things: Kilogram, the SI base unit of mass. ... The liter (spelled liter in American English and litre in Commonwealth English) is a unit of volume. ... Aramid fiber (1961) is a fire-resistant and strong synthetic fiber. ...


UHMWPE fibers are used in bulletproof vests, bow strings, climbing equipment, fishing line, spear lines for spearguns, high performance sails, suspension lines on sport parachutes, rigging in yachting, kites and kites lines for kites sports. Spectra is also used as a high-end Wakeboard line. This article or section does not adequately cite its references or sources. ... This image depicts a typical bow, as made by the Huns, lying against a tree. ... A sling is an item of climbing equipment consisting of a tied or sown loop of webbing that can be wrapped around sections of rock, hitched (tied) to other pieces of equipment or even tied directly to a tensioned line using a special prussik knot, for anchor extension or equalisation. ... Fishing line is any cord made for fishing. ... // Dutch fishermen using tridents in the 17th century Night spear fishing, Amazon basin, Peru. ... A gaff-rigged cutter flying a mainsail, staysail and genoa jib For other uses, see Sail (disambiguation). ... The Apollo 15 capsule landed safely despite a parachute failure. ... Yachting is a physical activity involving boats. ... A Wakeboard is the board for wakeboarding. ...


For body armor, the fibers are generally aligned and bonded into sheets, which are then layered at various angles to give the resulting composite material strength in all directions. Recently developed additions to the US Military's Interceptor body armor, designed to offer arm and leg protection, are said to utilise a form of Spectra or Dyneema fabric.[citation needed] ... A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct within the finished structure. ... Interceptor body armor in woodland camouflage with groin and neck protector. ...


Spun UHMWPE fibers excel as fishing line as they have less stretch, are more abrasion resistant, and are thinner than traditional monofilament line. Fishing line is any cord made for fishing. ... Abrasion on the palm of a right hand, shortly after falling Abrasions on elbow and lower arm, still healing. ... Monofilament line is a thin string made from a single fiber. ...


Equipment used for climbing includes cord and webbing made of combinations of Dyneema and nylon yarns. Dyneema "Slings", multi-purpose sewn loops of webbing, have gained popularity for their low weight and bulk, though unlike their nylon counterparts they exhibit very low stretch, making them unsuitable for limiting forces in a fall. Dyneema's very high lubricity leads to poor knot holding ability, and has led to the recommendation to use the triple fisherman's knot rather than the traditional double fisherman's knot in 6mm Dyneema core cord. A good hitch to use with this material is the Palomar knot (this knot is not common among climbers but has become popular with anglers).[citation needed] Rock climbers on Valkyrie at The Roaches in Staffordshire, England. ... Webbing is a strong fabric woven as a flat strip or tube of varying width and fibers often used in place of rope. ... Nylon is a generic designation for a family of synthetic polymers first produced on February 28, 1935 by Wallace Carothers at DuPont. ... Yarn Spools of thread Yarn is a long continuous length of interlocked fibers, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery and ropemaking. ... A sling is an item of climbing equipment consisting of a tied or sown loop of webbing that can be wrapped around sections of rock, hitched (tied) to other pieces of equipment or even tied directly to a tensioned line using a special prussik knot, for anchor extension or equalisation. ... The Fishermans knot is a type of knot. ... Use the double fishermans knot to tie together two ropes of unequal sizes. ... A hitch is a type of knot used for binding rope to a part of a ship or other vehicle or object. ... The palomar knot is a knot that is used for securing a fishing line to the fishing lure. ...


It is also used in both skis, and snowboards often in combination with carbon fiber, reinforcing the fiberglass composite material, adding stiffness and improving its flex characteristics. The UHMWPE is often used as the base layer, that contacts the snow and is structured with abrasives to absorb and retain wax. Carbon fiber composite is a strong, light and very expensive material. ... Bundle of fiberglass Fiberglass (also called fibreglass and glass fibre) is material made from extremely fine fibers of glass. ... A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct within the finished structure. ...


High-performance ropes for sailing and parasailing are made of Dyneema as well.[citation needed] Dyneema is the preferred material for sport kite lines for two main reasons. First the low stretch means that control inputs to the kite are transferred quickly and secondly the low friction allows the kite to remain controllable up to about ten twists in the line.[citation needed] For either of the songs named Sailing, see Sailing (song). ... Parasailing in Punta Cana, Dominican Republic Parasailing, also known as parascending, is a recreational activity where a person (two or three people may also ride at the same time) is towed behind a vehicle (usually a boat) while attached to a parachute. ... Delta style sport kite on the ground, ready to be launched. ...


The extremely low friction coefficient of UHMWPE makes it a common topsheet for boxes in terrain parks.[citation needed] A terrain park is an outdoor area that contains jumps and half-pipes that allow snowboarders and skiers to do tricks. ...


Medical Applications in Total Joint Replacement

UHMWPE has over 40 years of clinical history as a successful biomaterial for use in hip, knee, and most recently (since the 1980s), for spine implants. [5] An online repository of information and review articles related to medical grade UHMWPE, known as the UHMWPE Lexicon, was started online in 2000 [6].


Joint replacement components have historically been made from "GUR" resins. These powder materials are produced by Ticona, typically converted into semi-forms by companies such as Quadrant and Orthoplastics, and then machined into implant components and sterilised by device manufacturers.[citation needed] Ticona is an international manufacturer of engineering polymers. ...


UHMWPE was first used clinically in 1962 by Sir John Charnley and emerged as the dominant bearing material for total hip and knee replacements in the 1970s. Details about the "discovery" of UHMWPE for orthopedic applications by Charnley and his engineering associate Harry Craven are available [7]. Sir John Charnley (born August 29, 1911–August 5, 1982) was a British orthopaedic surgeon. ...


Historically, there were unsuccessful attempts to modify UHMWPE to improve its clinical performance until the development of highly crosslinked UHMWPE in the late 1990s. [citation needed]


One unsuccessful attempt to modify UHMWPE was by blending the powder with carbon fibers. This reinforced UHMWPE was released clinically as "Poly Two" by Zimmer in the 1970s [5]. The carbon fibers had poor compatibility with the UHMWPE matrix and its clinical performance was inferior to virgin UHMWPE. [citation needed]


A second attempt to modify UHMWPE was by high pressure recystallisation. This recrystallised UHMWPE was released clinically as "Hylamer" by DePuy in the late 1980s [5]. When gamma irradiated in air, this material exhibited susceptibility to oxidation, resulting in inferior clinical performance related to virgin UHMWPE. Today, the poor clinical history of Hylamer is largely attributed to its sterilisation method and there has been a resurgence of interest in studying this material (at least among certain research circles).[citation needed] Hylamer fell out of favor in the United States in the late 1990s with the development of highly crosslinked UHMWPE materials, however negative clinical reports from Europe about Hylamer continue to surface in the literature.


Highly crosslinked UHMWPE materials were clinically introduced starting in 1998 and has rapidly become the standard of care for total hip replacements, at least in the United States [5]. These new materials are crosslinked with gamma or electron beam radiation (50-105 kGy) and then thermally processed to improve its oxidation resistance.[citation needed] Five year clinical data, from several centers, are now available demonstrating its superiority relative to conventional UHMWPE for total hip arthroplasty.[citation needed] Clinical studies are still underway to investigate the performance of highly crosslinked UHMWPE for knee arthroplasty.[citation needed] Hip replacement is the most successful, cheapest and safest form of replacement surgery. ... Arthroplasty (literally formation of joint) is an operative procedure of orthopaedic surgery performed for replacing the arthritic or dysfunctional joint surface with something better or remodeling or realigning the joint by osteotomy or some other procedures. ...


Another important medical advancement for UHMWPE in the past decade has been the increase in use of fibers for sutures. Medical grade fibers for surgical applications are currently produced by DSM under the "Dyneema Purity" trade name.[citation needed]


Skis

The bottom of most modern skis—the surface that contacts the snow—is coated with UHMWPE. In this context, the material is known as P-tex.[citation needed] Because the material is a thermoplastic, gouges can easily be filled. A shaped, twin-tip alpine ski. ...


Small Bicycle Parts

Freestyle BMX company Tree Bicycle Co. uses UHMWPE in a guard used to protect a bicycles front sprocket/chainwheel during a stunt in which one grinds on their sprocket guard. A BMX Race. ...


Inline Skating

Aggressive inline skating use UHMWPE for Soul Plates and frames to assist how well the skates slide when preforming grinding tricks


Skateboarding

Downhill and trick slide skateboarders and use UHMWPE for the plastic pucks used on sliding gloves.[citation needed]


Garland Manufacturing has sponsored both solar cars and inline skating projects with its GARDUR brand of UHMWPE. The company has limited-run capabilities for new applications in sport markets.[citation needed]


Front1 Most high-level short track speed skaters use a cut resistant suit made of Dyneema or a comparable textile like kevlar.[citation needed] Short track speed skating (also Shorttrack speedskating) is a form of competitive ice speed skating. ... Chemical structure of Kevlar. ...


Hockey

Ice hockey and field hockey sticks against US Patent 5333857 use Dyneema as a material to reinforce the body of the stick.[8]


See also

A synonym for the more widely accepted term, alkene. ... Aramid fiber (1961) is a fire-resistant and strong synthetic fiber. ... Chemical structure of Kevlar. ... Chemical structure of Kevlar. ... poly(p-phenylene-2,6-benzobisoxazole) Zylon is a trademarked name for a range of thermoset polyurethane materials manufactured by the Toyobo Corporation. ... Synthetic fibers are the result of extensive research by scientists to increase and improve upon the supply of naturally occurring animal and plant fibers that have been used in making cloth and rope. ... Linear low density polyethylene (LLDPE) is a substantially linear polymer, with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. ... LDPE has SPI resin ID code 4 Low-density polyethylene (LDPE) is a thermoplastic made from oil. ... HDPE has SPI resin ID code 2 High-density polyethylene (HDPE) is a polyethylene thermoplastic made from petroleum. ... ...

References

  1. ^ Hoechst: Annealing (Stress Relief) of Hostalen GUR
  2. ^ Dyneema capacity 400 or 600 tons/yr per production line
  3. ^ 2008 expansion to ten lines
  4. ^ Tensile and creep properties of UHMWPE fibres
  5. ^ a b c d Kurtz SM, The UHMWPE Handbook, Academic Press, New York, 2004.
  6. ^ UHMWPE Lexicon
  7. ^ [1]
  8. ^ US Patent 5333857

External links


  Results from FactBites:
 
Ultra high molecular weight polyethylene - Plastics Wiki (0 words)
Ultra high molecular weight polyethylene (UHMWPE), also known as high modulus polyethylene (HMPE) or high performance polyethylene (HPPE), is a thermoplastic.
UHMWPE is a type of olefin and, despite relatively weak Van der Waals bonds between its molecules, derives ample strength from the length of each individual molecule.
UHMWPE is synthesized from monomers of ethylene, which are bonded together to form what is called ultra high molecular weight polyethylene (or UHMWPE).
  More results at FactBites »

 
 

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