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| The term '''elastomer''' is often used interchangeably with the term ], and is preferred when referring to vulcanisates. They are ]s existing above their ], so that considerable segmental motion is possible. At ambient temperatures rubbers are thus relatively soft (]~3MPa) and deformable. Their primary uses are for ]s, ]s and molded flexible parts. | The term '''elastomer''' is often used interchangeably with the term ], and is preferred when referring to ]. They are ]s existing above their ], so that considerable segmental motion is possible. At ambient temperatures rubbers are thus relatively soft (]~3MPa) and deformable. Their primary uses are for ]s, ]s and molded flexible parts. | ||
| Elastomers are usually ]s (requiring vulcanization) but may also be ]. The long polymer chains ] 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. | Elastomers are usually ]s (requiring vulcanization) but may also be ]. The long polymer chains ] 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. | ||
Revision as of 23:37, 7 February 2006
The term elastomer is often used interchangeably with the term rubber, and is preferred when referring to vulcanisates. 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. 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
- Viton® (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.