Polyethylene

[ethylene]

Polyethylene is the most popular plastic in the world.It has a very simple structure, the simplest of all commerical polymers. A molecule of polyethylene is a long chain of carbon atoms, with two hydrogen atoms attached to each carbon atom.

[polyethylene]

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Uses of polyethylene:

  • Grocery bags
  • Shampoo bottles
  • Children's toy
  • Bullet proof vests

    Types of polyethylene

    Sometimes it's a little more complicated. Sometimes some of the carbons, instead of having hydrogen attached to them, will have long chains of polyethlene attached to them. This is called branched, or low-density polyethylene, or LDPE. When there is no branching, it is called linear polyethylene, or HDPE. linear polyethylene is much stringer than branched polyethlene, but branched polyethylene is cheaper and easier to make.
    [linear and branched polyethlene]

    Linear polyethylene is normally produced with molecular weights in the range of 200,000 to 500,000, but it can be made even higher. Polyethylene with molecular weights of three to six million is referred to as ultra-high molecular weight polyethylene, or UHMWPE. UHMWP can be used to make fibers which are so strong they replaced Kevlar for use in bullet proof vests.

    [vinyl]

    **Branched polyethylene is made by free radical vinyl polymerization.

    **Linear polythylene is made by a more complicated procedure called Ziegler-Natta polymerization.

    **UHMWPE is made using metallocene catalysis polymerization.

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