Silk has been a coveted commodity ever since 2640 B.C., according to legend. But even if silk’s history isn’t as long as believed, its unique properties and historical influence are still remarkable. The effects of the production of silk include the opening of trade routes, the development of cities, and the blossoming of industries such as dyeing and weaving. Also, a search for a cheap alternative to silk caused major inventions as well, like hosiery and parachutes. Silk and its artificial relative nylon have actually made a larger impact on history and economics than one might think, and it’s all due to the chemical structure of silk.
Silk is a protein produced by the silkworm in the form of a cocoon, originally found in China, where the silkworm is common. The production of silk thread involves raising the silkworms in controlled temperatures with plenty of mulberry leaves to eat, heating cocoons made by the silkworms until the chrysalis inside is killed, and putting the cocoon in boiling water to remove the silkworm’s secretion that holds the silk together. One cocoon can make 400 to 3,000 yards of thread, which would be sold mostly to nobility and the imperial family for a high price. When the selling and trade of silk took off, a network of trade routes throughout central Asia was established as the Silk Road, which stretched into the Mediterranean, India, and present-day Turkey. Despite China’s efforts to retain a monopoly over silk, including punishing smuggling attempts with death, the production of silk, known as sericulture, spread to other countries. In fact, there is a legend that in 552 the first recorded incident of industrial espionage occurred when two monks managed to smuggle silkworm eggs in their hollow canes to Constantinople, enabling the West to begin producing silk. Once this act of smuggling was performed, western countries quickly began producing silk. By the 1300’s, Italy had established a booming sericulture industry, thought to be one of the financial foundations for the Renaissance to occur. From Italy, sericulture spread to France, England, and eventually the United States. There has always been a high demand for silk, yet it has always been expensive, so, starting in the late nineteenth century, a search for an artificial substitute began. After many trials and errors, nylon arrived on the scene in 1938, with characteristics most similar to silk than any other attempt before it. While Wallace Carothers was researching polymers for the Du Pont Fibersilk Company, he helped add evidence to the theory about giant molecules of polymers that Staudinger received the Nobel Prize for in 1953. After four years of research, Carothers created nylon, the first synthesized molecule to have the most properties similar to silk, such as sag and wrinkle resistance. Nylon was also much cheaper than silk. In 1938, nylon was first used for toothbrush bristles, but then it got its big break in 1939 when nylon hosiery was introduced. From there, nylon began to be used for fishing lines, tennis racket strings, surgical sutures, electrical wire coatings, and more, because it was strong, durable, and light. With World War II, production of nylon changed to be coarser than the thread used for hosiery so nylon could be used in military products such as weather balloons, mosquito netting, rope, and parachutes. After World War II, nylon production went back to domesticity, nylon being found in clothing, skiwear, carpets, furnishings, and more in the 1950’s. Nylon was also the first compound that could be used as a replacement for metal. Both silk and nylon had a great historical impact throughout the world. Silk opened trade routes, caused the development of big silk-producing cities, and helped establish other industries like dyeing, spinning, and weaving. Nylon impacted the modern world by becoming the base of many artificially made products and leading the way to other man-made manufactures.
The desirable properties of silk that caused its high price and association with the upper class can be attributed all to silk’s chemical structure. Silk is a protein and a polymer, which means it is composed of repeating molecules. Proteins consist of an amino group (NH2) attached to a carbon atom next to an organic acid group (COOH), with a side group or chain composed of one of 22 groups that code for a different amino acid. Glycine, with a side group of H, alaine (with CH3), and serine (with CH2OH) compose about 85% of silk. These three amino acids have the smallest side groups possible, which is responsible for silk’s smooth texture. The repeating molecules in silk differ from those of other fabrics because not all the molecules have the same side groups, which means they are different amino acids. Theoretically, each amino acid could be one of the 22 possible, but it has been estimated that 80-85% of the amino acids in silk follow the pattern of glycine-serine-slycine-alanine-flycine-alanine. Amino acids bond with each other by removing a water molecule between two, the H of one’s NH2 group and the OH of the other’s COOH, and forming an amide group. These chains of amino acids are in zigzag form and line up parallel with other chains going in the opposite direction. The two chains have cross attractions between molecules that cause them to stay together in a pleated structure, that is, with side groups on one chain facing up while side groups on the other face down. This pleated structure causes many of silk’s desired characteristics, like its stretch resistance, smoothness, its luster, and its “sparkle” (which is caused by irregularities in the pleated structure that break up reflected light). The remaining 15-20% of silk that isn’t made of the three main amino acids can easily absorb dyes and color. Nylon’s chemical structure is very similar to silk, which is why it has such similar characteristics that led to its fame. Silk is made of amino acid units with an acid on one end and an amine on the other, but nylon has two acid groups on the ends of one monomer unit and two amine groups on the ends of the other. The unit with two acids is known as adipic acid and has COOH at both ends, and the other unit, known as 1,6-diaminohexane, has NH2 on both ends. These two monomers still remove a water molecule between the two to make an amide bond, which is responsible for nylon’s properties similar to silk.
Today the uses of nylon is just as important as it was in the past, I think the only difference is that it has become so commonplace it is no longer a big deal in our minds. Silk has never lost its value since its beginning. Although today it isn’t making history like it did in the past, it is still a hot commodity associated with the wealthy. Nylon opened the world to synthesized molecules and man made products, but now that more molecules have been synthesized and used to make artificial commodities that once were strictly natural-made, nylon has died down a bit. It is still used for many products such as hosiery and parachutes, but it is no longer the hot new thing of the century. I agree with the authors’ statement that silk and nylon have a great significance to our past and our present. One can use many other examples in history to know that anything that creates jobs will have striking effects on the economy, such as World War II or the Industrial Revolution. Both the production of silk and, later on, nylon created jobs and in silk’s case, created large trade routes and manufacturing cities. Also, nylon’s convenient timing of being created just before World War II allowed it to be used for military items, which could possibly be interpreted as helping the technology of the military to help the soldiers’ performance. Both silk and nylon have such desirable characteristics for fabric and clothing, they both shaped the idea of fashion and the fashion industry. Despite the slight decline in fame for both silk and nylon, they both play an important role in our culture and economy, by shaping fashion trends and creating jobs for manufacture. And both have always played an important role since each was found or created, and both have made huge impacts on our world.