Unit 3 - Topic 3 - Plastics and Polymers

Most of the plastics we use have been made by scientists from chemicals that were obtained from crude oil. Plastics are examples of polymers - very large molecules formed by the joining of many small molecules called monomers. The uses of plastics are related to their chemical properties.

Poly(ethene) Poly(propene) Poly(tetrafluoroethene) Poly(chloroethene)

Ethene

Propene

Tetrafluoroethene

Chloroethene

Packaging film, trash and grocery bags

Plastic parts for cars and other methods of travel

Non-stick coating for pans and other cookware

Pipe insulation

Polymers are long molecules that are made using monomers. Monomers are unsaturated small molecules and polymers are saturated large molecules.

Plastics and synthetic fibres are made from giant molecules. Joining together many thousands of smaller molecules called monomers makes these giant molecules. The giant molecule is called a polymer as joining many small molecules together makes it. Poly means many

The most common monomer is ethene, C2H4, used to make the plastic called polythene, known as polythene.

Because, monomers add together to give 1 larger molecule.

All addition polymers are based on a monomer containing a C=C. This means the polymer chain will repeat every 2-carbon atoms. This is called the REPEATING UNIT.

A substance reacts with oxygen

CO2 + H2O

CO2 = Limewater turns cloudy H2O = Cobalt Chloride paper turns from blue to pink

Many plastics and synthetic fibres are flammable. Apart from the danger of fire, these materials can produce poisonous gases when they burn. There are 3 poisonous gases produced when plastics burn: Carbon Monoxide (CO) Hydrogen Chloride (HCl) Hydrogen Cyanide (HCN)