Low-density polyethylene
2138217
222200763
2008-06-28T01:33:13Z
222.154.110.37
/* Physical qualities */
{{Unreferenced|date=February 2008}}
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'''Low-density [[polyethylene]]''' ('''LDPE''') is a [[thermoplastic]] made from [[petroleum|oil]]. It was the first grade of polyethylene, produced in 1933 by [[Imperial Chemical Industries]] (ICI) using a high pressure process via [[Radical_polymerization|free radical polymerisation]] [http://www.pacia.org.au/_uploaditems/docs/3.polyethylene.pdf|1]. Its manufacture employs the same method today.
==Properties==
LDPE is defined by a density range of 0.910 - 0.940 g/cm³. It is unreactive at [[room temperature]]s, except by strong oxidizing agents, and some [[solvent]]s cause [[swelling]]. It can withstand temperatures of 80 °C continuously and 95 °C for a short time. Made in translucent or opaque variations, it is quite flexible, and tough to the degree of being almost unbreakable.
It has more [[Branching (chemistry)|branching]] (on about 2% of the carbon atoms) than [[high-density polyethylene|HDPE]], so its [[intermolecular force]]s ([[instantaneous-dipole induced-dipole attraction]]) are weaker, its [[tensile strength]] is lower, and its [[resilience]] is higher. Also, since its molecules are less tightly packed and less crystalline because of the side branches, its [[density]] is lower.
===Chemical resistance===
* Excellent resistance (no attack) to dilute and concentrated [[acid]]s, [[alcohol]]s, [[Base (chemistry)|bases]] and [[ester]]s
* Good resistance (minor attack) to [[aldehyde]]s, [[ketone]]s and [[vegetable oil]]s
* Limited resistance (moderate attack suitable for short-term use only) to [[aliphatic]] and [[aromatic]] [[hydrocarbons]], [[mineral oil]]s, and [[oxidizing agent]]s
* Poor resistance, and not recommended for use with [[Halogenated hydrocarbons]].[http://www.dynalabcorp.com/technical_info_ld_polyethylene.asp]
==Applications==
LDPE is widely used for manufacturing various containers, dispensing bottles, wash bottles, tubing, plastic bags for computer components, and various [[molding (process)|molded]] laboratory equipment. <!-- and many more, care to add? --> Its most common use is in [[plastic bag]]s. Other products made from it include:
* Trays & general purpose containers
* Food storage and laboratory containers
* Corrosion-resistant work surfaces
* Parts that need to be [[weldable]] and [[machining|machinable]]
* Parts that require flexibility, for which it serves very well
* Very soft and pliable parts
* Six-pack soda can rings
* Extrusion coating on paperboard and aluminum laminated for beverage cartons.
* Computer components, such as hard drives, screen cards and disk-drives.
* Playground Slides
==See also==
* [[High-density polyethylene]]
* [[Linear low-density polyethylene]]
* [[Ultra-high-molecular-weight polyethylene]]
{{polymer-stub}}
[[Category:Polyolefins]]
[[Category:Plastics]]
[[Category:Packaging materials]]
[[nl:LDPE]]
[[ja:低密度ポリエチレン]]