Today, with the discovery of so many compact discs or CDs, we do have CD cases to store these data storage devices. The material that is used for packing and also in CD cases plastic model kits is called as polystyrene. Let us now find out how this useful material came into existence...
Discovery of Polystyrene
German apothecary called as Edward Simon accidentally discovered polystyrene in the year 1839. This discovery was recorded on the website of the Plastics Historical Society. Edward discovered a new chemical called as "Styrol" which was an oily substance that he had isolated from a natural resin. He had hardened the resin for a few days and assumed that it had oxidised. In 1845, English chemist John Blyth and German chemist August Willhelm von Hoffmann proved that the same reaction took place in the absence of oxygen, showing that it was not oxidation.
Stabilising the Monomer
Then, in the year 1866, Marcelin Berthelot demonstrated that the hard material was actually a polymer. The problem was that the monomer was very unstable and used to turn into the polymer before it should thereby preventing the useful application of polystyrene, as it came to be known in the mid-twentieth century.
In the year 1922, a step forward was taken when Dufraisse and Moureu found that the monomer could be stabilised by adding small amounts of aromatic amines and phenols. This led to the use of the reaction to study the mechanism of polymerisation all through the 1920s.
Commercial Manufacture of polystyrene
Work done by Herman Staudinger and Carl Wolff enabled the I.G Farben Company in Germany to begin the first commercial manufacture of polystyrene in the year 1931. They developed a reactor vessel which helped in extruding polystyrene through a heated tube and cutter and produced the polymer in a pellet form which was much easier to use.
Wide Usage of Polystyrene
The polymer which is otherwise hard and colourless can be cast into moulds with very fine detail. In this form it was used for economical, rigid plastic items, such as plastic model assembly kits, plastic cutlery, and CD cases. Butadiene/styrene co-polymers were used to produce synthetic rubber, and this was used extensively during the Second World War.
Polystyrene's main use now, of course, is in its expanded form. This form is produced by heating a mixture of polystyrene and a gaseous blowing agent like pentane or carbon dioxide. With the help of steam foam is made, which is then cooled to make the material most commonly associated with the name polystyrene. The bubbles of the trapped air in the material give it very low thermal conductivity thereby making it useful as an insulation material in building applications. It is also used for many types of packaging where fragile material needs protection from impact damage.
The only problem with polystyrene is that it is not bio-degradable. It is light in weight and hence it floats on water and is easily blown by wind. It is hence recommended to recycle the waste expanded polystyrene, by using it in the manufacture of more polystyrene and save our environment in turn.