Discovery of Nylon
An organic chemist, Wallace Carathers produced nylon, a very commonly found polymer, in the year 1935. However, until 1937, the discovery remained unpatented and in the year 1938, the discovery of nylon was announced. The chemical name of nylon is polyhexamethyleneadipamide. It took seven years for the chemist to accomplish success on this project. He also discovered the fact that the liquid form of the polymer solidified quickly when it was blown through the nozzles that were ultra-thin. The amazing fact about the solidified polymers or resilient fibers is that they were thinner than human hair.
Naming of Nylon
The naming of these fibers became a big problem. First, they were named as Fiber 66. However, as the scientist was not happy with the name and wanted much better name, he had set up a naming committee that came up with 400 names. Out of them, Duparooh and No Run were accepted till sometime. Then, the committee reformed the No Run to Nylon, which remained till date. Though nylon does not carry any kind of Many people believe that the name nylon is a combination of two cities in which the product was launched, i.e. New York (NY) & London (LON). After sometime, the discoverer committed suicide by consuming cyanide.
Due to its property of thermo-plasticity, nylon saw its usage first, in the form of bristles in the toothbrushes of the common man. Then, it was used in the stockings worn by women in the year 1939, which increased its popularity. These stockings were considered delicate to the skin yet strong. Nylon was thought to be one of the reasons for the loss of silk market. Anyone would be amazed to know that it is the pioneer artificial or man-made fiber that was derived from air, coal and water. Moreover, the structure of nylon is quite complicated, as it has repeating links that are connected with the help of peptide or amide bonds.
Chemical Preparation of Nylon
Nylon is also known to be condensation polymer that is formed when equal quantities of diamine and dicarboxylic acid react. In this process, peptide bonds develop at either ends of each monomer. The number of carbons given by a single monomer is specified by the numerical suffix, in which diamine is the first and diacid is the second. In Nylon 6-6 (6/6), one 6 refers to diamine or hexamethylene diamine and the other 6 to diacid or adipic acid. Moreover, six carbons are donated to the polymer chain. Due to the presence of identical reactive group at either ends of every monomer, the amide bond direction between the monomers is reversed. Therefore, in the laboratory, it is possible to prepare nylon 6, 6 from adipic chloride, if adipic acid is not available. Daltons is the unit for measuring nylon strength and ten thousand Daltons are necessary to get strong nylon. Sometimes, it becomes next to impossible to get correct proportions, due to which you can find deviation and bond breakage in nylon. To solve this problem, at the room temperature, nylon salt that is solid and crystalline is formed, by adding acid and base in equal ratios. The base and acid neutralize one another. This salt mixture, when heated to 285 degrees Celsius reacts and forms nylon.
To compete with German company, BASF, DuPont copyrighted nylon 6, 6. The polycaprolactam or homopolymer nylon 6 is prepared by the polymerization of aminocaproic acid or ring opening polymerization. When the peptide bond of caprolactam breaks, the free active groups on the sides have two new bonds. In this, the amide bonds are towards the same direction. Therefore, the properties of nylon 6, 6 and nylon 6 are almost the same, except for the melting temperature, which is low for nylon 6.
Other Nylon Polymers
Nylon 5, 10 is another polymer, in which Carothers showed interest even before nylon 6, 6. This polymer is prepared by combining sebacic acid and pentamethylene diamine. Moreover, it has higher properties than nylon 6,6. However, due to the cost involved in preparing it, it was not given much importance.
Properties of Nylon
The high viscosity in the fluid form enables it to form random coils. Due to the crystalline regions in nylon, it gets strength and firmness. Further, the amorphous regions give it elastic property. Alternative to amorphous regions are lamellar crystals. To get lot of fibers, all the amide bonds should be in trans configuration. Moreover, the backbone of nylon is symmetrical and regular. However, crystalline property in block nylon is less. Nylon can be dyed easily, since it is clear and colorless. When people use multithreaded nylon rope or cord, it is important that they keep their palms dry as they are quite slippery and moreover, it can get unraveled.
Nylon came to be used in the making of tents, outerwear, sporting bags, combat uniforms, bridal veils, parachutes, carpets, flak vests, vehicle tires, ropes, and so on. Moreover, the solid nylon finds its usage in the mechanical parts and also as an engineering matter. Processes like extrusion, casting and injection molding are used for processing the nylon of engineering grade. In cast nylon, the Nylon 6 is the commonly and easily available commercial grade. In ordinary, the Type 6/6 Nylon 101 is the commonly available commercial grade.