Silk and Nylon

            

            Silk has always been a symbol of wealth and luxury, a fabric that could only be afforded by some, and takes back on the period of kings and queens, where extravagant fabrics were being made. This material opened trades between the East and the rest of the world, helping establishing other industries and develop cities which were dependent on this trade and manufacture of its’ products. Silk was without a doubt very expensive, and could not be afforded by all, and because of that reason an artificial silk was created, this much cheaper material that shared the same primary characteristics with silk was named nylon.

            Silk was such a valuable material loved by the wealthy due to its’ properties. Silk has a smooth feel to it giving the gentle sensation of caressing your skin, bringing also warmth in the cold weather and freshness in the hot weather. Adding to that, silk takes dye really well, portraying very attractive and beautiful colors, which create the extravagant and rich feeling that the wealthy loved so much. All this properties of silk are then due to its’ chemical structure. Silk is a polymer composed of alpha-aminoacids, mostly glycine, alanine and serine which bond together through peptide bonds, forming chains with a zigzag arrangement where the R side groups, (that determine the type of aminoacid) are alternating in each side of the chain. These chains will then lie parallel to each other and be held with cross attractions forming a pleated sheet structure. This type of structure is very flexible making silk resistance to stretching, and its smooth feel comes from the fact that the R groups are all similar in size creating this even surface which also has the ability to reflect light, which gives silk a beautiful glow. Adding to that silk was also admired by its ability to take dye color so fast, and this is also due to the pleated structure, in which other aminoacids, different from the previously mentioned, have side groups with the ability to bond with dye molecules, making it easy for this fabric to take color.

            This material, which has been loved and admired by many for more than four and a half millennia, was first produced by the Chinese with the cultivation of the silkworm. This larva is the main source of the natural silk that would be obtained from its cocoons. Each cocoon had the ability to produce threads of raw silk with lengths that could reach four hundred to more than three thousand yards.  China had the main power over the silk production, stopping any situations in which secrets from its production could leak to outsiders, and decrease their profit. Silk, as mentioned previously, was very valuable and it could be even used as payments, so its trade was also very valuable to the ones who had the power over it. All the attempts China had done to stop the leak of the silk secrets were however in vain when two monks smuggled silkworm eggs and brought them outside of China to the West. From the fourteenth and fifteenth century sericulture spread around the Mediterranean and brought great prosperity to countries like Italy and France in which silk production and its products originated a thriving industry and may have created the financial backing for the Renaissance movement originated in Italy during the era. By the twentieth century, the United States became the biggest manufacturers of silk products even though silk production had shown to be unsuccessful.

            There was a big demand for silk, even though its price never decreased very much and was still an expensive fabric to use. Since the demand was so great people started to search for replacements, and attempting to replicate this molecule and create synthetic silk which would be more affordable and still carried the same valued characteristics. This unfortunately did not happen, due to the natural structure of silk which was very hard to imitate due to the varied sequence of aminoacids and would make the synthetic product even more expensive than the natural one. What was instead discovered and produced, by Chardonnet, was not synthetic silk, but an artificial one, having different structures but the same desired properties. This artificial silk which mimicked the natural one, was produced with collodion (nitrocellulose). A solution of this substance was forced through a set of tiny holes forming fibers that resembled the silk fiber. This material was later named Chardonnet silk, and resembled some of the favorable properties of natural silk, however unlike it, this material was highly flammable and could even be explosive, something predictable since collodion was one of the nitro compounds mentioned in the last entry. This bad side of the material was its ruin, making it a bad product to commercialize. Another method made in England using another cellulose based artificial silk, produced viscose silk when viscose liquid was forced through a spinneret and into an acid bath, which would regenerate the cellulose into filaments. This method was later used in the production of rayon also composed of cellulose threads, and which has the shine and fast ability to take dye just like silk. However, this artificial substitute also had a flaw in the fact that it would absorb water an undesired property. With this drawback of rayon, the non-cellulose based Nylon entered the scene becoming the ultimate substitute of silk being the closest to the natural silk. Discovered by Wallace Carothers, the polyamide Nylon is constituted by two monomers, adipic acid which has two acid groups, and 1,6-diaminohexane with two amine groups. These two monomers are alternatively connected through amide links which are made with condensation reactions, also realizing water in the process.

Nylon was at first commercialized in toothbrush bristles, but with times innumerous uses started to arise for this artificial silk. Besides being cheaper, nylon had all the good properties of natural silk, and none of the bad sides of rayon or cotton. This created a great demand for this material since it was such an ideal product than was perfect for stocking, hosiery products, fishing nets, badminton rackets, and surgical sutures between many others. Even during the World War II nylon was very important in the manufacture of products like tire cords, ropes, mosquito netting and many other military items. After the war the use of this material did not decrease, going back to its previous uses, and developing new and varied ones, being also the first ‘engineering plastic’ strong enough to substitute metals.

            The search and desire for silk have since the past created a lot of wealth and prosperity to nations. Industries and countries developed thanks to this fabric and first attempts of espionage were done to have the power over it. Still today we see the importance of silk, this fabric is still seen has something beautiful and luxurious, representing wealth. Our necessity for silk has open door for the discovery of innumerous new materials and substances, and it was the setting point for the discovery of the so important and needed nylon. This material is still today used in innumerous areas, and its importance did not decrease since so many of our daily objects still use nylon. The authors have perfectly shown to us the influences and breakthroughs that silk and nylon have created. This importance shown to the readers by the authors can still for sure be seen today.