Information AboutNylon |
| CATEGORIES ABOUT NYLON | |
| plastics | |
| synthetic fibers | |
| polyamides | |
| dupont | |
| dielectrics | |
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Nylon is a generic designation for a family of Synthetic Polymer s first produced on February 28 , 1935 by Wallace Carothers at DuPont . OVERVIEW Nylon is a Thermoplastic silky material, first used commercially in a nylon- Bristle d Toothbrush (1938), followed more famously by women's “nylons” Stocking s (1940). It is made of Repeating Units linked by Peptide Bond s (another name for Amide Bonds ) and is frequently referred to as '' Polyamide '' (PA). Nylon was the first Commercially successful polymer and the first Synthetic Fiber to be made entirely from Coal , water and air. These are formed into Monomer s of intermediate Molecular Weight , which are then reacted to form long Polymer chains. It was intended to be a synthetic replacement for Silk and substituted for it in Parachute s and also making things like ropes, flak vests, vehicle tires, combat uniforms and many other military uses after the United States entered World War II in 1941, making stockings hard to find until the war's end. Nylon fibers are now used in Fabric s, bridal veils, carpets, guitar strings and Rope s, and solid nylon is used for Mechanical parts, Drumstick tips and as an Engineering material. Engineering grade Nylon is processed by extrusion, casting & Injection Molding . Type 6/6 Nylon 101 is the most common commercial grade of Nylon, and Nylon 6 is the most common commercial grade of cast Nylon. CHEMISTRY Nylons are → N terminal . In the laboratory, nylon 6,6 can also be made using Adipoyl Chloride instead of adipic It is difficult to get the proportions exactly correct, and deviations can lead to chain termination at molecular weights less than a desirable 10,000 of the Acid and the Base to neutralize each other. Heated to 285 °C, the salt reacts to form nylon polymer. Above 20,000 daltons, it is impossible to spin the chains into Yarn , so to combat this, some Acetic Acid is added to react with a free amine end group during polymer elongation to limit the molecular weight. In practice, and especially for 6,6, the monomers are often combined in a water solution. The water used to make the solution is evaporated under controlled conditions, and the increasing concentration of "salt" is polymerized to the final molecular weight. DuPont patented History of Nylon US Patent 2,130,523 'Linear polyamides suitable for spinning into strong pliable fibers', U.S. Patent 2,130,947 'Diamine dicarboxylic acid salt' issued and U.S. Patent 2,130,948 'Synthetic fibers', all issued 20 September 1938 nylon 6,6, so in order to compete, other companies (particularly the German BASF ) developed the Homopolymer Nylon 6 , or Polycaprolactam — not a condensation polymer, but formed by a Ring-opening Polymerization (alternatively made by polymerizing Aminocaproic Acid ). The peptide bond within the caprolactam is broken with the exposed Active Groups on each side being incorporated into two new bonds as the monomer becomes part of the polymer backbone. In this case, all amide bonds lie in the same direction, but the properties of nylon 6 are sometimes indistinguishable from those of nylon 6,6 — except for melt temperature (N6 is lower) and some fiber properties in products like carpets and textiles. There is also nylon 9. Nylon 5,10, made from Pentamethylene Diamine and Sebacic Acid , was studied by Carothers even before nylon 6,6 and has superior properties, but is more expensive to make. In keeping with this naming convention, "nylon 6,12" (N-6,12) or "PA-6,12" is a copolymer of a 6C diamine and a 12C diacid. Similarly for N-5,10 N-6,11; N-10,12, etc. Other nylons include copolymerized dicarboxylic acid/diamine products that are ''not'' based upon the monomers listed above. For example, some Aromatic nylons are polymerized with the addition of diacids like Terephthalic Acid (→ Kevlar ) or Isophthalic Acid (→ Nomex ), more commonly associated with polyesters. There are copolymers of N-6,6/N6; copolymers of N-6,6/N-6/N-12; and others. Because of the way polyamides are formed, nylon would seem to be limited to unbranched, straight chains. But "star" branched nylon can be produced by the condensation of dicarboxylic acids with Polyamine s having three or more Amino Group s. The general reaction is: : A molecule of Water is given off and the nylon is formed. Its properties are determined by the R and R' groups in the monomers. In nylon 6,6, R' = 6C and R = 4C Alkane s, but one also has to include the two carboxyl Carbons in the diacid to get the number it donates to the chain. In Kevlar , both R and R' are Benzene rings. NYLON FIBER The Federal Trade Commission s' Definition for Nylon Fiber: A manufactured fiber in which the fiber forming substance is a long-chain synthetic polyamide in which less than 85% of the amide-linkages are attached directly (-CO-NH-) to two aliphatic groups.
Basic Concepts of Nylon Production
This process creates Nylon 6,6 , made of hexamethylene diamine with six carbon atoms and acidipic acid, as well as six carbon atoms.
Nylon 6,6
Nylon 6
Full Nylon Production Model Producers The producers of nylon include: Honeywell Nylon Inc., Invista, Wellman Inc. among many others. The Dupont Company, is the most famous pioneer of the nylon we know today. The companies above now produce the nylon used in our everyday lives. Characteristics
BULK PROPERTIES Above their amide (-CO-NH-) groups are very Polar , so nylon forms multiple Hydrogen Bond s among adjacent strands. Because the nylon backbone is so regular and symmetrical, especially if all the amide bonds are in the ''trans'' Configuration , nylons often have high crystallinity and make excellent fibers. The amount of crystallinity depends on the details of formation, as well as on the kind of nylon. Apparently it can never be Quench ed from a Melt as a completely amorphous solid. Nylon 6,6 can have multiple parallel strands aligned with their neighboring peptide bonds at coordinated separations of exactly 6 and 4 carbons for considerable lengths, so the Carbonyl Oxygen s and amide Hydrogen s can line up to form interchain Hydrogen Bond s repeatedly, without interruption. Nylon 5,10 can have coordinated runs of 5 and 8 carbons. Thus parallel (but not antiparallel) strands can participate in extended, unbroken, multi-chain β-pleated Sheets , a strong and tough supermolecular structure similar to that found in natural Silk Fibroin and the β-keratins in Feather s. (Proteins have only an amino acid α-carbon separating sequential -CO-NH- groups.) Nylon 6 will form uninterrupted H-bonded sheets with mixed directionalities, but the β-sheet wrinkling is somewhat different. The three-dimensional disposition of each Alkane Hydrocarbon Chain depends on Rotation s about the 109.47° Tetrahedral bonds of singly-bonded carbon atoms. When Extruded into fibers through pores in an Industrial Spinneret , the individual polymer chains tend to align because of Viscous Flow . If subjected to Cold Drawing afterwards, the fibers align further, increasing their crystallinity, and the material acquires additional Tensile Strength . {Link without Title} In practice, nylon fibers are most often drawn using heated rolls at high speeds. Block nylon tends to be less crystalline, except near the surfaces due to Shear ing Stresses during formation. Nylon is Clear and Color less, or milky, but is easily Dye d. Multistranded nylon cord and rope is slippery and tends to unravel. The ends can be Melt ed and fused with a heat source such as a Flame or Electrode to prevent this. There are carbon fiber/nylon Composities with higher Density than pure nylon. When dry, polyamide is a good electrical insulator. However, polyamide is Hygroscopic . The absorption of water will change some of the Material 's properties such as its Electrical Resistance . Nylon is less absorbant than wool or cotton. HISTORICAL USES Bill Pittendreigh , DuPont , and other individuals and corporations worked diligently during the first few months of World War II to find a way to replace Asian Silk with nylon in Parachute s. It was also used to make Tire s, Tent s, Rope s, Poncho s, and other Military supplies. It was even used in the production of a high-grade paper for U.S. Currency . At the outset of the war, Cotton accounted for more than 80% of all fibers used, and manufactured and Wool fibers accounted for the remaining 20%. By August 1945, manufactured fibers had taken a market share of 25% and cotton had dropped. Some of the terpolymers based upon nylon are used every day in packaging. Nylon has been used for Meat wrappings and Sausage sheaths. ETYMOLOGY In 1940 John W. Eckelberry of DuPont stated that the letters "nyl" were arbitrary and the "on" was copied from the suffixes of other fibers such as Cotton and Rayon . A later publication by DuPont (''Context'', vol. 7, no. 2, 1978 ) explained that the name was originally intended to be "No-Run" ("run" meaning "unravel"), but was modified to avoid making such an unjustified claim and to make the word sound better. The story goes that Carothers changed one letter at a time until DuPont's management was satisfied. But he was not involved in the nylon project during the last year of his life, and committed suicide before the name was coined. Two theories about the origin of the name claim that it is an Acronym of "Now you've lost, Old Nippon " (N.Y.L.O.N.), or that it stands for " New York - London ". In the latter case, it is claimed that these were the two cities where the product was researched and developed, or that the inspiration came from a New York to London airplane ticket. There is no evidence for the 'airline ticket' theory, though some compelling evidence of the latter from contemporary researchers at Oxford University who assisted in development...Oxford can be viewed as London from New York, but Nylox would have been more accurate. USES
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