M.+Killeen-Reaction+Wiki

=**Polyethylene**= < Some final products made with the help of Polyethylene.
 * **Uses:** || **thermoplastics, fibers** ||
 * **Monomer:** || **ethylene** ||
 * **Polymerization:** || **free radical chain polymerization, Ziegler-Natta polymerization, metallocene catalysis polymerization** ||
 * **Morphology:** || **highly crystalline (linear), highly amorphous (branched)** ||
 * **Melting temperature:** || **137°C** ||
 * **Glass transition temperature:** || **-130 to -80°C** ||

Polyethylene was discovered in 1933 by Reginald Gibson and Eric Fawcett at the British industrial giant Imperial Chemical Industries (ICL).This is the polymer that everyone probably sees most in their daily lives. This reaction is the most popular plastic that we have in the world today. Helping us to make grocery bags, shampoo bottles, childrens toy's and they even help to make bullet proof vests. When looking at the outside of this material and how versatile it is contributing to many different aspects of life, it has a very smple structure. It is actually the simplest of all polymer commercials. A molecule of this reaction is simply a long chain of carbon atoms with two hydrogen atoms attached to each carbon. This trend is represented shortly in this model of the reaction:

Another, more clearer and easier to understand, example of the reaction can be looked at by this model of it:



Sometimes some of the carbon atoms within this reaction will be attached to long chains of polyethylene instead of having hydrogen atoms attached. This is called branced, or low-density polyethylene, or LDPE. Linear polyethylene is when there isnt any branching, also being called HDPE. The stronger of the two polyethylene goes to the linear but the branched polyethylene is cheaper and a lot easier to produce and manufacture. Here are two pictures that help you to visualize what each one of these different molecules of polyethylene looks like: Linear polyethylene is normally produced with molecular masses between the range of 200,000 to 500,000 but can be made even higher. Polyethylene with masses of three to six million are referred to as ultra-high molecular weight polyethylene, or UHMWPE. This kind of polyethylene can be involved in making fibers (ones that are so strong that theyve replaced the use of Kevlar in the manufacturing of bullet proof vests. Another use for this strong material is skating rinks which can be made by using large sheets of it instead of using ice.

< Bullet Proof Vest

ExXon Mobile Chemical is the leading global Polyethylene (PE) producer and supplier. They have the broadest PE product portfolio and are well placed to offer high performance relative to other polymers and alternative materials such as glass, metal or paper.


 * **Type of Polyethylene** || ==Commercial Uses== ||
 * __UHWMPE__ (ultra-high molecular weight PE) || Can and bottle handling machine parts, moving parts on weaving machines, bearings, gears, artificial joints, edge protection on hockey rinks, butchers’ chopping boards ||
 * __HMWPE__ (high molecular weight polyethylene), __HDPE__ (high density PE) || Milk Jugs, Detergent Bottles, Margarine tubs, Garbage containers, Water pipes ||
 * __HDXLPE__ (high density cross-linked PE), __PEX__ (Cross-linked PE), __MDPE__ (Medium density PE) || Gas pipes and fittings, sacks, shrink film, packaging film, carrier bags, screw closures ||
 * __LDPE__ (low density PE), __LLDPE__ (Linear low density PE) || Predominantly used in film applications due to its toughness, flexibility and relative transparency ||
 * __VLDPE__ (very low density PE) || Hose and tubing, ice and frozen food bags, food packaging and stretch wrap ||

Bibliography: [|http://pslc.ws/macrog/pe.htm] [|http://www.packagingtoday.com/introplasticexplosion.htm] http://www.3dchem.com/molecules.asp?ID=332