Plastics are everywhere today. They are used to make a huge variety of products in our homes, offices and sometimes even inside our bodies.
PLASTICS are everywhere today. They are used to make a huge variety of products in our homes, offices and sometimes even inside our bodies.
Millions of tonnes of them are thrown away each year. But before 1856, they did not exist at all.
Nylon, used to make stockings, is a synthetic material, which means it does not exist in nature.
The first of these ever made was Parkesine, a plastic developed by Alexander Parkes (1813–1890) in 1856.
It was made by treating wood fibres with nitric acid.
Soon after came celluloid, patented in 1870 by American printer John Hyatt (1837–1920), who made it as an alternative to ivory for billiard balls. Its most important use since has been as photographic film.
In 1909, Leo Baekeland (1863–1944) made Bakelite, a good electrical insulator moulded to make electrical appliances such as telephones and radios.
Nylon, Parkesine and celluloid are thermoplastics – they soften when heated and solidify when they cool.
But Bakelite is a thermoset: once moulded it ‘sets’ and will not soften again.
Plastics are polymers – they are made of very large molecules formed from lots of small ones joined together.
For example, polythene is made from small molecules of a compound called ethylene, obtained from crude oil.
Most modern plastics are made from compounds that come from oil or natural gas.
In the quest to find new and better synthetic materials, chemists have strived to understand the process of polymerisation.
Several important materials were made early on – but often in quantities that were too small, in forms that were unusable or without their inventors realising what they had done.
Polyvinyl chloride (PVC) was first made in the laboratory in 1872 but did not become a useful product until the 1940s.
Usually referred to as ‘vinyl’, it became the standard material for making gramophone records.
Nylon was developed by Wallace Carothers (1896–1937), who joined U.S. manufacturing giant DuPont in 1928.
It can be made into fine fibres, which can be woven or knitted into a fabric that is very ‘sheer’, like silk.
It is made by mixing two chemicals, whose molecules join to form a ‘copolymer’.
Carothers and his team tried thousands of variations before hitting on a winning combination.
Their first product was the Miracle Tuft toothbrush with nylon bristles (1938).
Their stockings went on sale in 1939 as a popular alternative to silk.
During World War Two, DuPont had to make nylon for parachutes, tents and ropes. When afterwards it resumed making stockings, demand seriously outstripped supply, leading to occasional violence among women clamouring for them.
Today, the plastics industry makes a colossal range of materials. There are about fifty main types of plastics and hundreds of different varieties of each type.
There is also a new class of plastics called ecoplastics, made from crops such as corn and sugar.
Scientists are working, so far with limited success, on biodegradable plastics that will not remain in landfill sites for thousands of years.
