The first human-made plastic was invented by Alexander Parkes in 1862; he called this plastic Parkesine. The development of plastics has come from the use of natural plastic materials (e.g., chewing gum, shellac) to the use of chemically modified natural materials (e.g., rubber, nitrocellulose, collagen, galalite) and finally to completely synthetic molecules (e.g., bakelite, epoxy, polyvinyl chloride, polyethylene).
Rubber
Natural rubber is an elastomer (an elastic hydrocarbon polymer) that was originally derived from a milky colloidal suspension, or latex, found in the sap of some plants. It is useful directly in this form (indeed, the first appearance of rubber in Europe is cloth waterproofed with unvulcanized latex from Brazil) but, later, in 1839, Charles Goodyear invented vulcanized rubber; this a form of natural rubber heated with, mostly, sulfur forming cross-links between polymer chains (vulcanization), improving elasticity and durability.
Cellulose-based plastics
In 1855, an Englishman from Birmingham named Alexander Parkes developed a synthetic replacement for ivory which he marketed under the trade name Parkesine, and which won a bronze medal at the 1862 World's fair in London. Parkesine was made from cellulose (the major component of plant cell walls) treated with nitric acid and a solvent. The output of the process (commonly known as cellulose nitrate or pyroxilin) could be dissolved in alcohol and hardened into a transparent and elastic material that could be molded when heated. By incorporating pigments into the product, it could be made to resemble ivory.
Bois Durci is a plastic moulding material based on cellulose. It was patented, in Paris in 1855, by Lepage. It is made from finely ground wood flour mixed with a binder, either egg or blood albumen or gelatine. The wood is probably either ebony or rose wood, giving a black or brown result. The mixture is dried and ground to a fine powder. The powder is placed in a plastic mould and compressed in a powerful hydraulic press whilst being heated by steam. The final product has a highly polished finish imparted by the surface of the plastic mould. |
