Array ( [0] => {{Short description|Polymer with rubber-like elastic properties}} [1] => {{More citations needed|date=April 2015}} [2] => [3] => An '''elastomer''' is a [[polymer]] with [[viscoelasticity]] (i.e. both [[viscosity]] and [[Elasticity (physics)|elasticity]]) and with weak [[intermolecular force]]s, generally low [[Young's modulus]] (E) and high failure strain compared with other materials.{{cite book|last=De|first=Sadhan K.|title=Rubber Technologist's Handbook, Volume 1|date=31 December 1996|publisher=Smithers Rapra Press|isbn=978-1859572627|page=287|edition=1st|url=https://books.google.com/books?id=2rxFOm68Ui8C&q=elastomer+low+%22young%27s+modulus%22&pg=PA287|access-date=7 February 2017|archive-url=https://web.archive.org/web/20170207113815/https://books.google.ca/books?id=2rxFOm68Ui8C&pg=PA287&dq=elastomer+low+%22young%27s+modulus%22&hl=en&sa=X&ved=0ahUKEwjZoe3z8_zRAhVL1oMKHfl3DWoQ6AEIJDAC#v=onepage&q=elastomer%20low%20%22young's%20modulus%22&f=false#v=onepage&q=elastomer%20low%20%22young's%20modulus%22&f=false|archive-date=2017-02-07|url-status=live}} The term, a [[portmanteau]] of ''elastic polymer'',{{cite web |last=Gent |first=Alan N. |title=Elastomer Chemical Compound |url=https://www.britannica.com/science/elastomer |website=Encyclopædia Britannica |access-date=7 February 2017 |archive-url=https://web.archive.org/web/20170207114149/https://www.britannica.com/science/elastomer |archive-date=2017-02-07 |url-status=live }} is often used interchangeably with ''[[Synthetic rubber|rubber]]'', although the latter is preferred when referring to [[Vulcanization|vulcanisates]].{{cite book |last=Alger |first=Mark |title=Polymer Science Dictionary |date=21 April 1989 |publisher=Springer |isbn=1851662200 |page=503 |url=https://books.google.com/books?id=OSAaRwBXGuEC&q=rubber+term+preferred+vulcanisates&pg=PA503 |archive-url=https://web.archive.org/web/20170207113813/https://books.google.ca/books?id=OSAaRwBXGuEC&pg=PA503&lpg=PA503&dq=rubber+term+preferred+vulcanisates&source=bl&ots=wVLr810pyp&sig=Ul09oC8mdMwqij3ILfDYqo7kl_g&hl=en&sa=X&ved=0ahUKEwjL1I629fzRAhVG64MKHeloC60Q6AEILTAE#v=onepage&q=rubber%20term%20preferred%20vulcanisates&f=false#v=onepage&q=rubber%20term%20preferred%20vulcanisates&f=false |archive-date=2017-02-07 |url-status=live |access-date=7 February 2017 }} Each of the [[monomer]]s which link to form the polymer is usually a compound of several [[Chemical elements|elements]] among [[carbon]], [[hydrogen]], [[oxygen]] and [[silicon]]. Elastomers are [[amorphous]] polymers maintained above their [[glass transition temperature]], so that considerable [[Segmental motion|molecular reconformation]] is feasible without breaking of [[covalent bonds]]. At [[ambient temperature]]s, such rubbers are thus relatively compliant (E ≈ 3 M[[Pascal (unit)|Pa]]) and deformable. Their primary uses are for [[Seal (mechanical)|seals]], [[adhesive]]s and molded flexible parts.{{Citation needed|date=July 2023}} [4] => [5] => [13] => [[File:IUPAC definition for an elastomer in polymer chemistry.png|thumb|right|550px|link=https://goldbook.iupac.org/terms/view/ET07547|IUPAC definition for an elastomer in polymer chemistry]] [14] => [15] => Rubber-like solids with elastic properties are called elastomers. Polymer chains are held together in these materials by relatively weak [[molecule|intermolecular bonds]], which permit the polymers to stretch in response to macroscopic stresses. [16] => [17] => [[File:Polymer picture.svg|thumb|upright|(A) is an unstressed polymer; (B) is the same polymer under stress. When the stress is removed, it will return to the A configuration. (The dots represent cross-links)]] [18] => [19] => Elastomers are usually [[thermoset]]s (requiring vulcanization) but may also be [[thermoplastic]] (see [[thermoplastic elastomer]]). The long polymer chains [[cross-link]] during curing (i.e. vulcanizing). The molecular structure of elastomers can be imagined as a 'spaghetti and meatball' structure, with the meatballs signifying cross-links. The elasticity is derived from the ability of the long chains to reconfigure themselves to distribute an applied stress. The covalent cross-linkages ensure that the elastomer will return to its original configuration when the stress is removed. [20] => [21] => Crosslinking most likely occurs in an equilibrated polymer without any solvent. The free energy expression derived from the Neohookean model of rubber elasticity is in terms of free energy change due to [[Deformation (physics)|deformation]] per unit volume of the sample. The strand concentration, v, is the number of strands over the volume which does not depend on the overall size and shape of the elastomer.{{Cite journal |last1=Boczkowska |first1=Anna |last2=Awietjan |first2=Stefan F. |last3=Pietrzko |first3=Stanisław |last4=Kurzydłowski |first4=Krzysztof J. |date=2012-03-01 |title=Mechanical Properties of Magnetorheological Elastomers under Shear Deformation |url=https://www.sciencedirect.com/science/article/pii/S135983681100360X |journal=Composites Part B: Engineering |volume=43 |issue=2 |pages=636–640 |doi=10.1016/j.compositesb.2011.08.026 |issn=1359-8368 }} Beta relates the end-to-end distance of polymer strands across crosslinks over polymers that obey random walk statistics. [22] => [23] => \Delta f_d = \frac{\Delta F_d}{V} = \frac{K_BT\nu_{el}\beta\lambda_1p^2 + \lambda_2p + 2\lambda_3p^2 - 3}{2} [24] => [25] => v_{el} = \frac{n_{el}}{V} , \beta = 1 [26] => [27] => In the specific case of shear deformation, the elastomer besides abiding to the simplest model of rubber elasticity is also incompressible. For pure shear we relate the shear strain, to the extension ratios lambdas. Pure shear is a two-dimensional stress state making lambda equal to 1, reducing the energy strain function above to: [28] => [29] => \Delta f_{d}= \frac{k_{B}T\nu_{s}\beta\gamma^2}{2} [30] => [31] => To get [[shear stress]], then the energy strain function is differentiated with respect to shear strain to get the shear modulus, G, times the shear strain: [32] => [33] => \sigma_{12} = \frac{d(\Delta f_{d})}{d\gamma} = G\gamma [34] => [35] => Shear stress is then proportional to the shear strain even at large strains.{{Cite journal |last1=Liao |first1=Guojiang |last2=Gong |first2=Xinglong |last3=Xuan |first3=Shouhu |date=2013-09-01 |title=Influence of Shear Deformation on the Normal Force of Magnetorheological Elastomer |url=https://www.sciencedirect.com/science/article/pii/S0167577X13006836 |journal=Materials Letters |volume=106 |pages=270–272 |doi=10.1016/j.matlet.2013.05.035 |issn=0167-577X }} Notice how a low shear modulus correlates to a low deformation strain energy density and vice versa. Shearing deformation in elastomers, require less energy to change shape than volume. [36] => [37] => \Delta f_d = W = \frac{G(\lambda_{1p}^2+\lambda_{2p}^2+\lambda_{3p}^2-3)}{2} [38] => [39] => ==Examples== [40] => '''Unsaturated rubbers''' that can be cured by sulfur vulcanization: [41] => * Natural [[polyisoprene]]: cis-1,4-polyisoprene [[natural rubber]] (NR) and trans-1,4-polyisoprene [[gutta-percha]] [42] => * Synthetic polyisoprene (IR for [[isoprene]] rubber) [43] => * [[Polybutadiene]] (BR for [[butadiene]] rubber) [44] => * [[Chloroprene]] rubber (CR), [[polychloroprene]], [[neoprene]] [45] => * [[Butyl rubber]] (copolymer of [[isobutene]] and isoprene, IIR) [46] => ** [[Halogenation|Halogenated]] butyl rubbers (chloro butyl rubber: CIIR; bromo butyl rubber: BIIR) [47] => * [[Styrene-butadiene]] rubber (copolymer of [[styrene]] and butadiene, SBR) [48] => * [[Nitrile rubber]] (copolymer of butadiene and [[acrylonitrile]], NBR), also called [[Plastic#Synthetic rubber|Buna N rubbers]] [49] => ** [[Hydrogenation|Hydrogenated]] nitrile rubbers (HNBR) Therban and Zetpol [50] => [51] => '''Saturated rubbers''' that cannot be cured by sulfur vulcanization: [52] => * EPM ([[ethylene propylene rubber]], a copolymer of [[ethene]] and [[propene]]) and [[EPDM rubber]] (ethylene propylene diene rubber, a terpolymer of ethylene, propylene and a [[diene]]-component) [53] => * [[Epichlorohydrin]] rubber (ECO) [54] => * [[Acrylic rubber]] (ACM, ABR) [55] => * [[Silicone rubber]] (SI, Q, VMQ) [56] => * [[Fluorosilicone]] rubber (FVMQ) [57] => * [[Fluoroelastomer]]s ([[FKM]], and FEPM) [[Viton]], [[Tecnoflon]], Fluorel, [[Aflas]] and Dai-El [58] => * Perfluoroelastomers ([[FFKM]]) Tecnoflon PFR, [[Kalrez]], Chemraz, Perlast [59] => * [[Polyether block amide]]s (PEBA) [60] => * [[Hypalon|Chlorosulfonated polyethylene]] (CSM) [61] => * [[Ethylene-vinyl acetate]] (EVA) [62] => [63] => '''Various other types of elastomers''': [64] => * [[Thermoplastic elastomer]]s (TPE) [65] => * The [[protein]]s [[resilin]] and [[elastin]] [66] => * [[Polysulfide]] rubber [67] => * [[Elastolefin]], elastic fiber used in fabric production [68] => * [[Poly(dichlorophosphazene)]], an "inorganic rubber" from [[Hexachlorophosphazene#Ring-opening polymerisation|hexachlorophosphazene polymerization]] [69] => [70] => ==See also== [71] => * [[Liquid elastomer molding]] [72] => * [[Rubber elasticity]] [73] => [74] => ==References== [75] => {{Reflist}} [76] => [77] => ==External links== [78] => * [http://www.listdryprocessing.com/fileadmin/user_upload/download/publications/2014-9_Article___Ad_CPRJ-E.pdf Efficient and eco-friendly polymerization of elastomers, By Andreas Diener, Product Manager at List AG] [79] => [80] => {{Authority control}} [81] => {{Clothing materials and parts}} [82] => [83] => [[Category:Elastomers| ]] [84] => [[Category:Materials science]] [85] => [[Category:Polymer physics]] [] => )
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Elastomer

Elastomers are a type of polymer that displays the characteristic property of elasticity. They are capable of returning to their original shape after being stretched, compressed, or deformed.

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They are capable of returning to their original shape after being stretched, compressed, or deformed. The word "elastomer" is derived from the combination of the terms "elastic" and "polymer". Elastomers have a wide range of applications due to their ability to undergo large deformations without permanent deformation. This Wikipedia page on elastomers provides a comprehensive overview of the topic. It covers the history, types, properties, and applications of elastomers. The history section explores the development of elastomers over time, from the discovery of natural rubber to the synthesis of synthetic elastomers. It also discusses the various advancements in elastomer technology and the commercial production of elastomers. The page describes different types of elastomers, including natural rubber, synthetic rubber, thermoplastic elastomers (TPEs), and liquid silicone rubber (LSR). Each type is explained in detail, highlighting its composition, properties, and applications. The properties section provides an in-depth analysis of the mechanical, thermal, electrical, chemical, and environmental characteristics of elastomers. Furthermore, the Wikipedia page discusses the commercial uses of elastomers across different industries, such as automotive, aerospace, construction, healthcare, and consumer products. It covers applications like tires, seals, gaskets, conveyor belts, adhesives, medical devices, and more. The page also highlights the importance of elastomers in enabling innovations and advancements in technology. Lastly, the Wikipedia page touches upon topics like elastomer processing techniques, environmental considerations, and the challenges faced in recycling elastomers. It provides references and external links for further exploration of the subject. Overall, this Wikipedia page serves as a valuable resource for anyone seeking knowledge about elastomers, their properties, and their vast range of applications.

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