Crude oil and by-products from processing it can be used to make the fibres and plastics which are in use today. An attractive looking and durable plastic chair comes from black crude oil!
The most widely used starting substance for making polymers is ethylene. It may be obtained by cracking crude oil fractions. In this process alkanes, with 15 to 25 carbon atoms per molecule, are broken into two smaller molecules, one an alkane and the other an alkene.
Ethylene, which is an alkene from cracking, is used to make polymers. The reactive double bonds in ethylene allow it to be converted into useful products such as the starting materials for important plastics. When ethylene is reacted with chlorine and oxygen it may form vinyl chloride, styrene and vinyl acetate. Further industrial reactions lead to making poly vinyl chloride (PVC), polystyrene and polyester. These are polymerisation reactions in which many identical small molecules combine together to form one large molecule. See https://www.britannica.com/science/polymerization The small molecules are called monomers and the large molecules are polymers. Ethylene polymerises to form Polyethylene, an addition polymer. Each molecule contains from a few hundred to a few thousand monomers.
Other important addition Polymers are Polyvinyl Chloride (PVC) and Polystyrene. PVC is made from the monomer vinyl chloride and Polystyrene is made from the monomer styrene. Polyethylene is used to make milk bottles,cling wrap and rubbish bins. PVC is made into electrical insulation and garden hoses while Polystyrene is used for disposable drink cups and modern furniture.
Condensation Polymers: These polymers form by the elimination of a small molecule (often water) when pairs of monomer molecules join together. Cellulose is a naturally occurring condensation polymer. A synthetic condensation polymer is nylon-6, which is a particular type of nylon formed from the monomer 6-aminohexanoic acid.
See the YouTube Video displayed above to see how this classroom experiment is done.
Proteins are condensation polymers made from amino acids. Amino acids are compounds with a carboxylic acid group at one end and an amine group at the other. When proteins form from amino acids, different amino acids are strung together sequentially in the one chain.
Cellulose is a polymer of which the monomer units are glucose. It is widely used as cotton (textiles), as paper and as a source of the chemicals ethanol and ethylene. See details abut cotton processing https://www.cotton.org/pubs/cottoncounts/fieldtofabric/harvest.cfm
Biopolymers are polymers which are made totally or in large part by living organisms. In the past this meant biologically synthesised polymers such as cellulose, starch, proteins and nucleic acids. The definition now includes chemically modified versions of natural polymers and polymers which can be produced by manipulating biological organisms. Products include
Rayon, fibres which can be used to make fabric; Cellophane, a form of rayon produced as a thin transparent film which is used for packaging; cellulose nitrate, was used for photographic and movie film.
There is a major problem with petroleum based polymers: they are not biodegradable. So when they go into landfill dumps they are not decomposed naturally. A solution being tried now is to develop biopolymers that have similar properties to synthetic polymers but which still retain biodegradability. Cornstarch is a useful carbohydrate with which to begin the biodegradable polymerisation process. In class you may heat it with vinegar and glycerine to make a biodegradable polymer pancake.
So polymers are powerful and significant chemical compounds. Check out the embedded links in the text above and the You Tube video.
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