Elastomer
Encyclopedia : E : EL : ELA : Elastomer
The term elastomer is often used interchangeably with the term rubber, and is preferred when referring to vulcanisates. Elastomer comes from two terms, elastic (describing the ability of a material to return to its original shape when a load is removed) and mer (from polymer, in which poly means many and mer means parts). Each link of the chain is the "-mer" or basic unit that is usually made of carbon, hydrogen, oxygen and/or silicon. To make the chain, many links or "-mers" are hooked or polymerized together. They are amorphous polymers existing above their glass transition temperature, so that considerable segmental motion is possible. At ambient temperatures rubbers are thus relatively soft (E~3MPa) and deformable. Their primary uses are for seals, adhesives and molded flexible parts.
Elastomers are usually thermosets (requiring vulcanization) but may also be thermoplastic (see thermoplastic elastomer). The long polymer chains cross-link during curing and account for the flexible nature of the material. The molecular structure of elastomers can be imagined as a 'spaghetti and meatball' structure, with the meatballs signifying cross-links.
Examples of elastomers
- Natural Rubber
- Polyisoprene
- *Butyl Rubber (copolymer of isobutylene and isoprene)
- Polybutadiene
- *Styrene Butadiene Rubber or SBR (copolymer of polystyrene and polybutadiene)
- *Nitrile Rubber (copolymer of polybutadiene and acrylonitrile), also called buna N rubbers
- Chloroprene Rubber, polychloroprene, also called Neoprene
- Silicone RTV
- FKM Viton®, Tecnoflon®(copolymer of vinylidene fluoride and hexafluoropropylene)
- Santoprene®
- Fluorosilicone Rubber
- EPM and EPDM rubber (ethylene propylene rubber, a copolymer of polyethylene and polypropylene)
- Polyurethane rubber
- Resilin
- Polyacrylic rubber (ABR)
- Epichlorohydrin rubber (ECO)
- Polysulfide Rubber
- Chlorosulfonated Polyethylene (CSM), (Hypalon®)
References
- Budinski, Kenneth G., Budinski, Michael K., Engineering Materials: Properties and Selection, 7th Ed, 2002. ISBN 0-13-030533-2.
- Expanation of properties and application of some elastomers: http://www.timcorubber.com/definitions/index.asp
- Comparison table of elastomer properties: http://www.timcorubber.com/definitions/Comparison_to_Elastomer_Properties.pdf
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