Wallace Carothers and Paul Schlack

Nylon 6/6 was first made on February 28, 1935 by the American chemist Wallace Carothers, working at DuPont. In Germany, by 1938, Paul Schlack of I.G. Farben Company had polymerized caprolactam, a different kind of polymer now known as nylon 6. Both are also called polyamides.

How Nylon is Made

This material is made via a condensation polymerization reaction and is formed by reacting di-functional monomers containing equal parts of amine and carboxylic acid. The amides form at both ends of the monomer in a process analogous to polypeptide biopolymers. The monomers for the 6/6 grade are adipic acid and hexamethylene diamine while the 6 grade requires a lactam or an amino acid. In each case the two molecules combine to make the polymer with only water left over. The water must then be removed or it inhibits the polymerization process. The name nylon 6 or nylon 6/6 is used based on how many carbon atoms there are between the two acid groups and the two amine groups.

Polyamides are strong, synthetic fibers that resists abrasion and will not shrink or stretch when washed. However, the material is damaged by ultraviolet light unless UV additives are used. Also it is flammable without the addition of flame retardants.  This material also has a higher water absorption rate than many other polymers. It is a thermoplastic made of repeating units linked by peptide bonds. Nylon 6/6 has a melting point of 509°F (265°C) while the melting point of nylon 6 is 428°F (220°C).

The Many Uses of Polyamides

The material started a revolution in the fiber industry. While previous attempts at “synthetic silk” had involved plant cellulose, this material was completely made from petrochemicals. DuPont began to make it commercially in 1939. Parachute fabrics, tooth brushes and women’s stockings were made of it. At the San Francisco Exposition in February 1939, “nylons” were first introduced. The stockings were an immediate hit. And nylon is used extensively in carpeting.

Nylon and the War Effort

The start of WWII in December of 1941 ended the use of the material in nylons at least temporarily. All production of this polymer was allocated to the war effort. It replaced Asian silk in parachutes and was used in tires, tents, ropes, ponchos and even the high-grade paper used in the production of U.S. currency. By the end of the war, the use of cotton fiber still predominated at 75% but synthetic fibers had risen to 15%. After the war, nylon stockings became all the rage once again.

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