Page 31 - Curriculum Visions Dynamic Book

 Bakelite appliance from the 1950s.
Bakelite
Bakelite is a plastic that is based
on the substances phenol and formaldehyde. It is a thermosetting plastic, meaning that when heat is applied, it hardens. Bakelite will not catch fire and so was used instead of the inflammable celluloid.
plastic (material): a carbon-based material consisting of long chains (polymers) of simple molecules. The word plastic is commonly restricted to synthetic polymers.
plastic (property): a material is plastic
if it can be made to change shape easily. Plastic materials will remain in the new shape. (Compare with elastic, a property where
a material goes back to its original shape.)
polymer: a compound that is made
of long chains by combining molecules (called monomers) as repeating units. (“Poly” means many, “mer” means part).
Celluloid: the first plastic
Alexander Parkes made the first plastic in 1856. It is made from cellulose nitrate and camphor. Many nitrate compounds are used in explosives, and celluloid material was used in World War 1 as a smokeless explosive. Not surprisingly, one of the problems with celluloid in the home or office is that it catches fire very easily. As a result it is rarely used today.
On the other hand cellulose, which is also prone to catch fire, is still widely used as a solvent for inks and paints because it dries very quickly. Car body paints, for example, are formulated with cellulose.
The history of plastics
The very first plastic, invented over a century ago, was called celluloid. It was a brittle white substance that was used as synthetic ivory. It was also used as the backing to rolls of photographic film.
It took half a century before the next plastic was invented. This was called Bakelite, after its inventor Leo Baekland. But after this, new forms of plastic were invented at a faster and faster rate.
The most well known plastics are nylon and polyester (both widely used for making garments), and polythene and polystyrene (used for making containers and packaging materials).
Most recently there has been a trend to make custom plastics, designed for a specific use.
 Celluloid table-tennis balls
Nonstick polymers
Nonstick surfaces on many pots and pans are made from polytetrafluoroethene
(Teflon), which is based on the two simple chemicals fluorine and ethene. It was
invented in 1938. It does not dissolve or burn. This is why it can be used on
pans and why fats, oils and other materials used in cooking have no
effect on it.
 A modern nonstick frying pan with a Teflon surface.
Also... Plastics solvents
A solvent is a liquid chemical compound used for dissolving another compound without reacting with it. Most organic materials do not dissolve in water, so water cannot be used as a solvent.
Most solvents have a low boiling point and are volatile, that is, they evaporate easily. A solvent used in polymer-based paints is cellulose nitrate;
a solvent for nail-varnish (cellulose acetate) is ethyl ethanoate (see page 29).
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