How is polypropylene made

Polypropene

After polyethene, polypropene or polypropylene is the second most important plastic with a market share of approx. 20% .Polypropene has almost exactly the same structure as polyethene, except that an additional methyl group is attached to every second carbon atom:

properties

The properties of polypropene (produced for the first time in 1951) are similar to those of polyethene, but because of the additional methyl groups, the density, melting point and mechanical strength are slightly higher. Polypropene is temperature resistant up to a maximum of 100 ÂșC! As a thermoplastic, polypropene can be easily deformed when heated.

use

Like polyethene, polypropene is also used in a variety of ways. In the production of synthetic fibers, polypropene has a share of over 30%. Polypropen also has a high market share in packaging films. In addition, glasses frames, plastic boxes, garden furniture, CD cases and many other everyday items are made from polypropene. Some cars contain up to 80 kg of polypropene parts, for example bumpers or molded parts for the interior of cars.

Synthetic fibers can also be drawn from polypropene. Yarns and fabrics are then made from these fibers.

synthesis

Like polyethene and many other plastics, polypropene is produced by polymerisation; the monomer for polypropene is alkene propene. Over 60% of the propene produced today is used for polypropene synthesis.

There are several methods of polypropene synthesis. In all processes, the propene gas is heated to up to 90 degrees Celsius under high pressure. By using certain catalysts, the chain length of the polymer can be determined and thus influence the properties of the plastic. It is therefore possible to produce both thin packaging films and stable plastic boxes or cases made of polyethene.

If a little ethene is mixed in with the propene, a copolymer is obtained in which propene and ethene monomers alternate randomly (irregularly). Disposable drinking cups and some plastic bottles are made from such an ethene-propene copolymer.

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