Ray Crandall, age 13, of Nogales, Ariz., for his question:
HOW IS NYLON MADE?
Nylon is a synthetic product that is one of the toughest, strongest and most elastic substances in existence. It is made of two chemical compounds: hexamethylenediamine and adipic acid. These compounds come from coal, water, air, petroleum, agricultural byproducts and natural gas.
Both hexamethylenediamine and adipic acid contain carbon and hydrogen.After they have been combined, they form another compound called hexamethylene diammonium adipate. The simpler name for this combination of compounds is nylon salt.
In a factory where nylon is made, the combination of compounds is put into a machine called an autoclave. The mixture is heated under pressure so that the molecules that make up each of the chemical substancescombine into larger molecules. This process of making large molecules out of smaller ones is called polymerization.
When polymerization is complete, the melted nylon comes out of the machines as a plastic ribbon. This is chilled and hardened on a metal roller.
The ribbon is then cut into chips and blended for uniformity. Next, nylon fibers are made by melting the chips over heated grids covered with inert gas to keep the oxygen of the air from getting into the melted nylon.
When the nylon becomes liquid, it is pumped through tiny holes of a device called a spinneret. The threads harden as soon as they strike the air and are wound on spools that handle about a half mile of thread per minute.
From one to as many as 2,520 strands or filaments from the spinneret are united into a textile nylon yarn. They are twisted a few turns per inch before they are wound on bobbins.
Nylon is cold drawn after it is made into yarn. When the thread is stretched, the molecules fall into parallel lines which give the yarn strength and elasticity.
The cold drawing process of nylon is carried out by unwinding the filament from one spool and winding it onto another in such a way as to make the winding up rate four or more times as fast as the unwinding rate. The pull between the spools stretches the yarn.
The size of the yarn depends on its original size and the degree of stretching. If the yarn is drawn to four times its original length, its diameter is only half of its original diameter.
The size of nylon is measured in deniers. A denier is the weight in grams of 9,000 meters or 9,843 yards of yarn. If you had 9,000 meters of nylon yarn that weighed 15 grams, it would be called 15 denier.
A chemist at the E.I. DuPont de Nemours and Company plant in Wilmington, Del., was the leader in the development of nylon. His name is Dr. Wallace Carruthers and he started his work in 1935. Commercial nylon was placed on the market in 1938.