Polyolefin

A polyolefin is a polymer produced from a simple olefin (also called an alkene with the general formula CnH2n) as a monomer. For example, polyethylene is the polyolefin produced by polymerizing the olefin ethylene. An equivalent term is polyalkene; this is a more modern term, although "polyolefin" is still used in the petrochemical industry. Polypropylene is another common polyolefin which is made from the olefin propylene.

Properties

A more specific type of olefin is a poly-"alpha"-olefin (or poly-α-olefin, sometimes abbreviated as PAO), a polymer made by polymerizing an "alpha"-olefin. An "alpha"-olefin (or α-olefin) is an alkene where the carbon-carbon double bond starts at the α-carbon atom, i.e. the double bond is between the #1 and #2 carbons in the molecule. Common alpha-olefins used as co-monomers to give a polymer alkyl branching groups are similar to 1-hexene or may be longer (see chemical structure below). Many poly-alpha-olefins have flexible alkyl branching groups on every other carbon of their polymer backbone chain. These alkyl groups, which can shape themselves in numerous conformations, make it very difficult for the polymer molecules to line themselves up side-by-side in an orderly way. Therefore, many poly-alpha-olefins do not crystallize or solidify easily and are able to remain oily, viscous liquids even at lower temperatures. Low molecular weight poly-"alpha"-olefins are useful as synthetic lubricants such as synthetic motor oils for vehicles used in a wide temperature range.

Even polyethylenes copolymerized with a small amount of alpha-olefins (such as 1-hexene, 1-octene, or longer) are more flexible than simple straight chain high density polyethylene, which has no branching. The methyl branch groups on a polypropylene polymer are not long enough to make typical commercial polypropylene more flexible than polyethylene.

External links

* [http://openlearn.open.ac.uk/mod/resource/view.php?id=196631 Polymer Structure]

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Look at other dictionaries:

  • polyolefin — [päl΄ē ō′lə fin] n. [ POLY + OLEFIN] any of a group of thermoplastic polymers, as polyethlylene or polypropylene, made from any simple alkene …   English World dictionary

  • polyolefin — /pol ee oh leuh fin/, n. Chem. any of a group of thermoplastic, stiff, light, and hard polymers obtained from the polymerization of simple olefins like propylene, used for injection molding, mostly in the automotive and appliance industries.… …   Universalium

  • polyolefin — poliolefinas statusas T sritis chemija apibrėžtis Nesočiojo angliavandenilio polimerizacijos ar kopolimerizacijos produktas. atitikmenys: angl. polyolefin rus. полиолефин …   Chemijos terminų aiškinamasis žodynas

  • polyolefin — noun Date: 1930 a polymer of an alkene (as polyethylene) …   New Collegiate Dictionary

  • Polyolefin — Polyolefine (fachsprachlich: Polyalkene) sind Polymere, die aus Kohlenwasserstoffen der Formel CnH2n mit einer Doppelbindung (Ethylen, Propylen, Buten 1, Isobuten) aufgebaut sind. Polyolefine sind teilkristalline Thermoplaste, die sich leicht… …   Deutsch Wikipedia

  • polyolefin — noun a) A polymer (such as polyethylene) made by the polymerization of an olefin b) A polyene …   Wiktionary

  • Polyolefin — Po|ly|o|le|fin; Syn.: Polyalken, (systematisch:) Polyalkylen: Sammelbez. für thermoplastische Polymerisate von α Olefinen (1 Alkenen) mit der allg. Formel (̶CR1R2 CH2)̶n mit R1, R2 im Allg. = H, CH3, C2H5, z. B. Polyethylen, Polypropylen,… …   Universal-Lexikon

  • polyolefin — poly·olefin …   English syllables

  • polyolefin — pol•y•o•le•fin [[t]ˌpɒl iˈoʊ lə fɪn[/t]] n. chem. any of a group of stiff, light, and hard thermoplastic polymers, used for injection molding, mostly in the automotive and appliance industries • Etymology: 1930–35 …   From formal English to slang

  • polyolefin — |pälē+ noun Etymology: poly + olefin 1. : an olefin containing many double bonds 2. : a polymer of olefin as polyethylene) * * * /pol ee oh leuh fin/, n. Chem. any of a group of thermoplastic, stiff, light, and hard polymers obtained from the… …   Useful english dictionary


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