Chemists had been trying to create a cheap man-made fibre for several years when the American Wallace Carothers invented nylon in 1953. Nylon stockings were introduced in 1928, and they were soon in enormous demand. The manufacturers said the new fibre was as ‘strong as steel and as delicate as a spider’s web’.
Carothers was an organic chemist, and in 1927 he was invited to lead a research team at E.I. du Pont Nemours and Company in Wilmington, Delaware. His goal was to invent a new synthetic material. It took him and his team nearly 11 years, while du Pont had to invest $27 million in the project.
Carothers was sure that a new material could be made by polymerization (combining small molecules into larger ones, so forming new compounds). He was trying to create a polymer with the same structure as silk that could be made in bulk.
In 1931, after four years of frustration, Carothers discovered a fibre finer and stronger than silk. By mixing adipic acid with hexamethylenediamine he produced a sticky compound which could be easily drawn out into a thin fibre. The first fibres he produced either melted at low temperatures or were too weak, and it took another four years to perfect ‘polymer 66’. He found that the polymerization process was inhibited by water droplets that the compound contained. By evaporating the water Carothers produced a very strong and elastic fibre.
Carothers had suffered from depression for many years, and on April 29, 1937, 20 days after applying for a patent for his invention, he committed suicide. He never knew that his discovery was to be called ‘nylon’, and he probably never dreamed that he had started a ‘materials revolution’. Today man-made fibres like nylon, acrylic and polyester far outsell natural fibres like nylon. Acrylic and polyester far outsell natural fibres like wool and cotton.
The technique for producing synthetic fibres has remained largely unchanged. Polymers in a liquid form are blown through very thin nozzles, called spinnerets. The fine jet solidifies almost immediately, and forms a fibre about a quarter the thickness of a human hair.
Next, the fibres are stretched, which aligns the long molecules along the length of the fibre, and gives nylon its shine and transparency. Nylon can be stretched up to five times its original length, before the molecules become aligned and bond tightly together to resist further stretching. The strong threads are then made into cloth.
Man-made fibre fabrics can already re-create most properties that natural fibres possess. Acrylic can be used to make fluffy fabrics or synthetic fur, with its very fine, downy fibres. Because of its strong but elastic molecular structure polyester has a wonderful ability to spring back into shape, which prevents garments from creasing.
Man-made fibres can also be combined with natural ones, so drip-dry material that needs no ironing can be made to feel natural.
Man-made fabric is easier to mass produce than either wool or cotton, which is just as well – each pair of nylon stockings is made from a single filament of nylon 4 miles (6.6km) long and knitted into 3 million loops.
Picture Credit : Google
