Ultra-high-molecular-weight polyethylene: Difference between revisions

UHMWPE is odorless, tasteless, and nontoxic.<ref>Wong, D. W. S.; Camirand, W. M.; Pavlath, A. E.; Krochta, J. M.; Baldwin, E. A. and Nisperos-Carriedo, M. O. (eds.) (1994) "Development of edible coatings for minimally processed fruits and vegetables" pp. 65–88 in ''Edible coatings and films to improve food quality'', Technomic Publishing Company, Lancaster, PA. {{ISBN|1566761131}}.</ref> It embodies all the characteristics of [[high-density polyethylene]] (HDPE) with the added traits of being resistant to concentrated [[acid]]s and [[alkali]]s, as well as numerous organic solvents.<ref>{{Citecite web|url=http://www.porex.com/technologies/materials/porous-plastics/pe/ |title=PE Material: Porex Porous Polyethylene for Plastic Filter Media |website=porex.com |url=http://www.porex.com/technologies/materials/porous-plastics/pe/ |access-date=2017-02-14}}</ref> It is highly resistant to corrosive chemicals except [[oxidizing acid]]s; has extremely low moisture absorption and a very low [[coefficient of friction]]; is self-lubricating (see [[boundary lubrication]]); and is highly resistant to [[Wearwear#Abrasive wear|abrasion]], in some forms being 15 times more resistant to abrasion than [[carbon steel]]. Its coefficient of friction is significantly lower than that of [[nylon]] and [[polyoxymethylene|acetal]] and is comparable to that of [[polytetrafluoroethylene]] (PTFE, Teflon), but UHMWPE has better abrasion resistance than PTFE.<ref>{{cite journal|doi=10.1016/j.compositesa.2005.05.023 |title=Free abrasive wear behaviour of UHMWPE composites filled with wollastonite fibres |year=2006 |last1=Tong |first1=Jin |last2=Ma |first2=Yunhai |last3=Arnell |first3=R. D. |last4=Ren |first4=Luquan |journal=Composites Part A: Applied Science and Manufacturing |volume=37 |issue=1 |pages=38–45 |doi=10.1016/j.compositesa.2005.05.023}}</ref><ref>{{cite journal|doi=10.1016/S0043-1648(96)07346-2 |title=Resistance to particle abrasion of selected plastics |year=1997 |last1=Budinski |first1=Kenneth G. |journal=Wear |volume=203–204 |pages=302–309 |doi=10.1016/S0043-1648(96)07346-2}}</ref>

Polymerization of UHMWPE was commercialized in the 1950s by [[Ruhrchemie]] AG,<ref name="Handbook">{{cite book |author=Kurtz, Steven M. |title=The UHMWPE handbook: ultra-high molecular weight polyethylene in total joint replacement |url=https://books.google.com/books?id=bkuFjppEdMcC |year=2004 |publisher=Academic Press |isbn=978-0-12-429851-4 |url=https://books.google.com/books?id=bkuFjppEdMcC}}</ref><ref>''Die Aktivitäten der Ruhrchemie AG auf dem Gebiet der Kohlevergasung''. In: ''Glückauf-Forschungshefte'', Jg. 44 (1983), pp. 140–145.</ref> which has changed names over the years. Today UHMWPE powder materials, which may be directly molded into a product's final shape, are produced by, [[Ticona]], [[Braskem]], [[Teijin]] (Endumax), [[Celanese]], and [[Mitsui Chemicals|Mitsui]]. Processed UHMWPE is available commercially either as fibers or in consolidated form, such as sheets or rods. Because of its resistance to wear and impact, UHMWPE continues to find increasing industrial applications, including the automotive and bottling sectors. Since the 1960s, UHMWPE has also been the material of choice for total joint [[arthroplasty]] in [[orthopedic]] and [[Vertebralvertebral column|spine]] implants.<ref name="Handbook"/>

UHMWPE fibers branded as Dyneema, commercialized in the late 1970s by the Dutch chemical company [[DSM (company)|DSM]], and as Spectra, commercialized by Honeywell (then AlliedSignal), are widely used in ballistic protection, defense applications, and increasingly in medical devices, sailing, hiking equipment, climbing, and many other industries.

UHMWPE is a type of [[polyolefin]]. It is made up of extremely long chains of polyethylene, which all align in the same direction. It derives its strength largely from the length of each individual molecule (chain). [[Van der Waals forces]] between the molecules are relatively weak for each atom of overlap between the molecules, but because the molecules are very long, large overlaps can exist, adding up to the ability to carry larger shear forces from molecule to molecule. Each chain is attracted to the others with so many van der Waals forces that the whole of the inter-molecular strength is high. In this way, large [[tensile stress|tensile]] loads are not limited as much by the comparative weakness of each localized van der Waals force.

When formed into fibers, the polymer chains can attain a parallel orientation greater than 95% and a level of [[crystallinity]] from 39% to 75%. In contrast, [[Kevlar]] derives its strength from strong bonding between relatively short molecules.

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 {{convert|130|to|136|C|F}},<ref>[http://chemyq.com/En/xz/xz4/39468nvyng.htm ultra high molecular weight polyethylene; UHMWPE]. chemyq.com</ref> and, according to DSM, it is not advisable to use UHMWPE fibres at temperatures exceeding {{convert|80|to|100|C|F}} for long periods of time. It becomes [[brittle]] at temperatures below {{convert|-150|C|F|sigfig=2}}.<ref>{{Citecite book|url=https://books.google.com/books?id=mrG3q9h__XYC |title=Handbook of Fiber Science and Technology Volume3: High Technology Fibers |last=Lewin |date=1996-07-09 |publisher=CRC Press |isbn=9780824794705 |language=en |url=https://books.google.com/books?id=mrG3q9h__XYC}}</ref>

The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the [[Polarpolar molecule|polar]] groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, nor [[wetting|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. In a similar manner, [[aromatic]] polymers are often susceptible to aromatic solvents due to [[aromatic stacking interaction]]s, an effect [[aliphatic]] polymers like UHMWPE are immune to. Since UHMWPE does not contain chemical groups (such as [[ester]]s, [[amide]]s, or [[hydroxyl]]ic groups) that are susceptible to attack from aggressive agents, it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms.

Under tensile load, UHMWPE will deform continually as long as the stress is present—an effect called ''[[Creepcreep (deformation)|creep]]''.

When UHMWPE is [[Annealingannealing (metallurgy)|annealed]], the material is heated to between {{convert|135&nbsp;°|C|abbr=on}} and {{convert|138&nbsp;°|C|abbr=on}} in an oven or a liquid bath of [[silicone oil]] or [[glycerine]]. The material is then cooled down at a rate of {{convert|5&nbsp;°|C/h|abbr=on}} to {{convert|65&nbsp;°|C|abbr=on}} or less. Finally, the material is wrapped in an insulating blanket for 24 hours to bring to room temperature.<ref>Hoechst: Annealing (Stress Relief) of Hostalen GUR</ref>

''Ultra-high-molecular-weight polyethylene'' (UHMWPE) is [[Chemicalchemical synthesis|synthesized]] from its [[monomers|monomer]] [[ethylene]], which is bonded together to form the base polyethylene product. These molecules are several [[orders of magnitude]] longer than those of familiar [[high-density polyethylene]] (HDPE) due to a synthesis process based on [[metallocene]] [[Kaminsky catalyst|catalysts]], resulting in UHMWPE molecules typically having 100,000 to 250,000 monomer units per molecule each compared to HDPE's 700 to 1,800 monomers.

UHMWPE is processed variously by [[compression moulding]], ram [[extrusion]], [[Spinningspinning (polymers)#Gel spinning|gel spinning]], and [[sintering]]. Several European companies began compression molding UHMWPE in the early 1960s. Gel-spinning arrived much later and was intended for different applications.

In gel spinning a precisely heated gel (of a low concentration of UHMWPE in an oil) is [[extruder|extruded]] through a [[Spinneretspinneret (polymers)|spinneret]]. The extrudate is drawn through the air, andthe thenoil cooledextracted inwith a watersolvent bathwhich does not affect the UHMWPE, and then dried removing the solvent. 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 [[Reptationreptation|entanglements]] are minimal. Entanglements make chain orientation more difficult, and lower the strength of the final product.<ref>{{cite journal |author1=Pennings, A.J. |author2=van der Hooft, R.J. |author3=Postema, A.R. |author4=Hoogsteen, W. |author5=ten Brinke, G. |title=High-speed gel-spinning of ultra-high molecular weight polyethylene |journal=Polymer Bulletin |doi=10.1007/BF00955487 |volume=16 |pages=167–174 |year=1986 |issue=2–3 |s2cid=137384856 |doi=10.1007/BF00955487 |url=https://pure.rug.nl/ws/files/14630135/1986PolymBullPennings.pdf |access-date=2019-07-13 |archiveurl-datestatus=2019-02-17dead |archive-url=https://web.archive.org/web/20190217202628/https://pure.rug.nl/ws/files/14630135/1986PolymBullPennings.pdf |urlarchive-statusdate=dead 2019-02-17}}</ref>

{{cleanupCleanup section|reason=Currently in a disorderly list format without bullet points. Maybe organize by how the fibers are used (rope, sheet, composite, single-strand)?|date=April 2023}}

'''Dyneema''' and '''Spectra''' are [[brand]]s of lightweight high-strength oriented-strand gels spun through a [[Spinneretspinneret (polymers)|spinneret]]. They have [[yield strength]]s as high as {{convert|2.4 [[|GPa]] (2.4&nbsp;kN/mm² or 350,000 [[Pounds per square inch|psi]])abbr=on}} and [[density]] as low as {{convert|0.97 |g/cm³|abbr=on}} (for Dyneema SK75).<ref>Crouch, Ian. 2016. The Science of Armour Materials. P229. Woodhead Publishing.</ref> High-strength steels have comparable yield strengths, and low-carbon steels have yield strengths much lower (around {{convert|0.5 |GPa|abbr=on}}). Since steel has a specific gravity of roughly 7.8, these materials have a strength-to-weight ratios eight times that of high-strength steels. Strength-to-weight ratios for UHMWPE are about 40% higher than for [[aramid]]. The high qualities of UHMWPE filament were discovered by Albert Pennings in 1968, but commercially viable products were made available by DSM in 1990 and [https://www.southernropes.co.uk/pages/our-hmpe Southern Ropes] soon after.. <ref>{{cite web |title=The story of Dyneema® |website=Dyneema® Project |url=https://www.thedyneemaproject.com/en_GB/the-fabrics/dyneema.html}}</ref>

Derivatives of UHMWPE yarn are used in composite plates in [[armor]], in particular, [[personal armor]] and on occasion as [[vehicle armor]]. Civil applications containing UHMWPE fibers are cut-resistant gloves, tear-resistant [[pantyhose|hosiery]], [[bow (weapon)|bow]] strings, [[Slingsling (climbing equipment)|climbing equipment]], automotive [[winch]]ing, [[fishing line]], spear lines for [[spearfishing|spearguns]], high-performance [[sail]]s, suspension lines on sport [[parachute]]s and [[paraglider]]s, [[rigging]] in [[yachting]], kites, and kite lines for kites sports.

For personal armor, the fibers are, in general, aligned and bonded into sheets, which are then layered at various angles to give the resulting [[composite material]] strength in all directions.<ref>{{cite web |publisher=Tote Systems Australia |title=Dyneema |url=http://www.tote.com.au/dyneema.htm}}</ref><ref>Bhatnagar, A. (ed.) (2006) ''Lightweight Ballistic Composites: Military and Law-Enforcement Applications''. Honeywell International. {{ISBN|1855739410}}</ref> Recently developed additions to the US Military's [[Interceptor body armor]], designed to offer arm and leg protection, are said to utilize a form of UHMWPE fabric.<ref>

|date=20 September 2019 }}</ref>

}}</ref> fencing clothing, stab -resistant vests, and as composite liners for vehicles.<ref>{{cite web

The use of UHMWPE rope for automotive winching offers several advantages over the more common steel [[wire rope]]. The key reason for changing to UHMWPE rope is improved safety. The lower mass of UHMWPE rope, coupled with significantly lower elongation at breaking, carries far less energy than steel or nylon, which leads to almost no [[snap-back]]. UHMWPE rope does not develop kinks that can cause weak spots, and any frayed areas that may develop along the surface of the rope cannot pierce the skin like broken steel wire strands can. UHMWPE rope is less dense than water, making water recoveries easier as the recovery cable is easier to locate than wire rope. The bright colours available also aid with visibility should the rope become submerged or dirty. Another advantage in automotive applications is the reduced weight of UHMWPE rope over steel cables. A typical {{convert|11&nbsp;|mm|abbr=on}} UHMWPE rope of {{convert|30 metres|m|abbr=on}} can weigh around {{convert|2&nbsp;|kg|abbr=on}}, the equivalent steel wire rope would weigh around {{convert|13&nbsp;|kg|abbr=on}}. One notable drawback of UHMWPE rope is its susceptibility to UV damage, so many users will fit winch covers in order to protect the cable when not in use. It is also vulnerable to heat damage from contact with hot components.

In [[climbing]], cord and [[webbing]] made of combinations of UHMWPE and nylon [[yarns|yarn]] have gained popularity for their low weight and bulk. They exhibit very low elasticity compared to their nylon counterparts, which translates to low [[toughness]]. The fiber's very high [[lubricity]] causes poor knot-holding ability, and it is mostly used in pre-sewn 'slings' (loops of webbing) — relying—relying on knots to join sections of UHMWPE is generally not recommended, and if necessary it is recommended to use the [[triple fisherman's knot]] rather than the traditional [[double fisherman's knot]].<ref>

Ships' [[hawser]]s and [[rope|cables]] made from the fiber (0.97 specific gravity) float on sea water. "Spectra wires" as they are called in the towing boat community are commonly used for face wires{{clarify|what
<ref>
A iscable aused faceto wire|date=September 2021}} assecure a lighterbarge alternativeto toa steeltowboat wires.

It is used in skis and snowboards, often in combination with [[carbon fiber]], reinforcing the [[fiberglass]] composite material, adding stiffness and improving its flex characteristics.{{clarify|how does it improve flex characteristics?|date=September 2021}}. The UHMWPE is often used as the base layer, which contacts the snow, and includes abrasives to absorb and retain wax.{{clarify|how do the abrasives absorb wax?|date=September 2021}}

It is also used in lifting applications, for manufacturing low weight, and heavy duty lifting slings. Due to its extreme abrasion resistance it is also used{{clarify|in what form?|date=September 2021}} as an excellent corner protection for synthetic lifting slings.

High-performance lines (such as [[backstay]]s) for [[sailing]] and [[parasailing]] are made of UHMWPE, due to their low stretch, high strength, and low weight.<ref>{{Citecite web|url=http://www.ballyribbon.com/fibers/spectra-dyneema/ |title=Spectra® and Dyneema® {{!}} Bally Ribbon Mills |website=Bally Ribbon Mills |language=en-US |url=https://www.ballyribbon.com/fibers/spectra-dyneema/ |access-date=2016-06-07}}</ref> Similarly, UHMWPE is often used for winch-launching [[Gliderglider (aircraft)|gliders]] from the ground, as, in comparison with steel cable, its superior abrasion resistance results in less wear when running along the ground and into the winch, increasing the time between failures. The lower weight on the mile-long cables used also results in higher winch launches.

UHMWPE was used for the {{convert|30-kilometre|km|abbr=on}} long, {{convert|0.6&ndash;|mm|abbr=on}} thick space tether in the ESA/Russian [[Young Engineers' Satellite 2]] of September, 2007.<ref>{{cite journal |journal=[[Nature (journal)|Nature]] |author=Katharine Sanderson |title=Dropping a line from space |volume=449 |date=2007-09-26 |page=387 |doi=10.1038/449387a |pmid=17898730 |issue=7161 |bibcode = 2007Natur.449..387S |doi=10.1038/449387a |doi-access=free }}</ref>

[[Dyneema Composite Fabric]] (DCF) is a laminated material consisting of a grid of Dyneema threads sandwiched between two thin transparent polyester membranes. This material is very strong for its weight, and was originally developed for use in racing yacht sails under the name 'Cuben Fiber'. More recently it has found new applications, most notably in the manufacture of lightweight and [[ultralight backpacking|ultralight]] camping and backpacking equipment such as tents, backpacks, and backpacksbear-proof food bags.

In archery, UHMWPE is widely used as a material for bowstrings because of its low creep and stretch compared to, for example, [[Dacron]] (PET).{{citation needed|date= November 2018}} Besides pure UHMWPE fibers, most manufacturers use blends to further reduce the creep and stretch of the material. In these blends, the UHMWPE fibers are blended with, for example, [[Vectran]].

In [[skydiving]], UHMWPE is one of the most common materials used for suspension lines, largely supplanting the earlier-used [[Dacron]], being lighter and less bulky.{{citation needed|date= November 2018}} UHMWPE has excellent strength and wear-resistance, but is not dimensionally stable (i.e. shrinks) when exposed to heat, which leads to gradual and uneven shrinkage of different lines as they are subject to differing amounts of friction during canopy deployment, necessitating periodic line replacement. It is also almost completely inelastic, which can exacerbate the opening shock. For that reason, Dacron lines continue to be used in student and some tandem systems, where the added bulk is less of a concern than the potential for an injurious opening. In turn, in high -performance parachutes used for [[Canopycanopy piloting|swooping]], UHMWPE is replaced with Vectran and HMA (high-modulus aramid), which are even thinner and dimensionally stable, but exhibit greater wear and require much more frequent maintenance to prevent catastrophic failure. UHMWPE are also used for reserve parachute closing loops when used with [[automatic activation device]]s, where their extremely low coefficient of friction is critical for proper operation in the event of cutter activation.

In 2007, manufacturers started incorporating anti-oxidants into UHMWPE for hip and knee arthroplasty bearing surfaces.<ref name=Handbook /> [[Vitamin E]] (a-tocopherol) is the most common anti-oxidant used in radiation-cross-linked UHMWPE for medical applications. The anti-oxidant helps quench free radicals that are introduced during the irradiation process, imparting improved oxidation resistance to the UHMWPE without the need for thermal treatment.<ref>Wannomae, K. K., Micheli, B. R.; Lozynsky, A. J. and Muratoglu, O. K. (2010) [http://www.ors.org/Transactions/56/2290.pdf "A new method of stabilising irradiated UHMWPE using Vitamin E and mechanical annealing"]. 56th Annual Meeting of the Orthopedic Research Society, 2290.</ref> Several companies have been selling antioxidant-stabilized joint replacement technologies since 2007, using both synthetic vitamin E as well as hindered phenol-based antioxidants.<ref>{{cite web |author=Spiegelberg, S.H. |date=2012 |title=UHMWPE for total joint arthroplasty: Past, present, and future |website=Bonezone |url=https://bonezonepub.com/2012/06/09/uhmwpe-for-total-joint-arthroplasty-past-present-and-future/}}</ref>

Another important medical advancement for UHMWPE in the past decade has been the increase in use of fibers for [[Surgicalsurgical suture|sutures]]. [[Medical-grade]] fibers for surgical applications are produced by DSM under the "Dyneema Purity" trade name.<ref>{{cite web |date=2017 |title=DSM introduces Dyneema Purity® Black fiber, the first black medical-grade UHMWPE fiber |website=DSM |url=https://www.dsm.com/biomedical/en_US/media-events/press-releases/2017/2017-03-07-dsm-introduces-dyneema-purity-black-fiber.html }}</ref>

===Wire/ and cable===

Fluoropolymer / HMWPE insulation cathodic protection cable is typically made with dual insulation. It features a primary layer of a fluoropolymer such as [[ECTFE]] which is chemically resistant to chlorine, sulphuricsulfuric acid, and [[hydrochloric acid]]. Following the primary layer is an HMWPE insulation layer, which provides pliable strength and allows considerable abuse during installation. The HMWPE jacketing provides mechanical protection as well.<ref>[https://www.current-voltage.com/definition-of-xlpe-cable-and-advantages/ "Cathodic Protection"] {{Webarchive|url=https://web.archive.org/web/20210802155222/https://www.current-voltage.com/definition-of-xlpe-cable-and-advantages/ |date=2021-08-02 }}. ''Performance of XLPE cable''.</ref>

UHMWPE is used in marine structures for the mooring of ships and floating structures in general. The UHMWPE forms the contact surface between the floating structure and the fixed one. Timber was and is used for this application also. UHMWPE is chosen as facing of fender systems for berthing structures because of the following characteristics:<ref>{{Citecite web |title=UHMWPE for marine structures |url=https://u-hubs.com/uhmwpe-for-marine-structures/|title=UHMWPE for marine structures|access-date=May 7, 2020}}</ref>

== See also ==

* [https://web.archive.org/web/20070929082933/http://www.patentstorm.us/patents/5342567-description.html US Patent 5342567 Process for producing high tenacity and high modulus polyethylene fibers, issued 1994-08-30 ]

* [httphttps://dspace.mit.edu/handle/1721.1/34092 Polymer Gel Spinning Machine] Christine A. Odero, MIT, 1994

* [http://www.campoly.com/index.php/download_file/view/158/191/ Analytical techniques to characterize radiation effects on UHMWPE] {{Webarchive|url=https://web.archive.org/web/20140424231819/http://www.campoly.com/index.php/download_file/view/158/191/ |date=2014-04-24 }}

* [http://www.campoly.com/index.php/download_file/view/361/190/ Next generation orthopedic implants using UHMWPE] {{Webarchive|url=https://web.archive.org/web/20140424233326/http://www.campoly.com/index.php/download_file/view/361/190/ |date=2014-04-24 }}

* [http://www.campoly.com/index.php/download_file/view/354/190/ Highly crosslinked VE-UHMWPE for hip and knee replacements] {{Webarchive|url=https://web.archive.org/web/20140424231814/http://www.campoly.com/index.php/download_file/view/354/190/ |date=2014-04-24 }}

* [https://www.energetic-plastics.com/uhmwpe-p00101p1.html UHMWPE Characteristics, Processing Methods, Applications ] {{Webarchive|url=https://web.archive.org/web/20190705014949/https://www.energetic-plastics.com/uhmwpe-p00101p1.html |date=2019-07-05 }}

* [https://www.energetic-plastics.com/info/polyethylenecomparison-i00045i1.html Polyethylene UHMWPE HDPE LDPE LLDPE – What are the differences?] {{Webarchive|url=https://web.archive.org/web/20210515013208/https://www.energetic-plastics.com/info/polyethylenecomparison-i00045i1.html |date=2021-05-15 }}

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