Nylon

Overview

Nylon is a polymer chains.

Nylon was intended to be a synthetic replacement for silk and substituted for it in many different products after silk became scarce during World War II. It replaced silk in military applications such as parachutes, flak vests, and was used in many types of vehicle tires.

Nylon fibers are used in a great many applications, including fabrics, bridal veils, carpets, musical strings and rope.

Solid nylon is used for mechanical parts such as gears and other low- to medium-stress components previously cast in metal. Engineering grade nylon is processed by extrusion, casting, and 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. Nylon is available in glass-filled and molybdenum sulfide-filled variants which increase structural and impact strength and rigidity or lubricity.

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 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^[1] nylon 6,6, so in order to compete, other companies (particularly the German 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 polyamines having three or more amino groups.

The general reaction is:

A molecule of benzene rings.

Nylon Fiber

The Federal Trade Commissions' 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.

• A synthetic thermoplastic fiber (Nylon melts/glazes easily at relatively low temperatures)
• Round, smooth, and shiny filament fibers
• cross sections can be either
  • trilobal to imitate silk
  • multilobal to increase staple like appearance and hand
• Its most widely used structures are multifilament, monofilament, staple or tow and is available as partially drawn or as finished filaments.
• Regular nylon has a round cross section and is perfectly uniform. The filaments are generally completely transparent unless they have been delustered or solution dyed. Thus, they are microscopically recognized as glass rods.
• Molecular chains of nylon are long and straight variations but have no side chains or linkages.
  • Cold drawing (step 18 on the model) can align the chains so they are oriented with the lengthwise direction and are highly crystalline.

• Nylon is related chemically to the protein fibers silk and wool.
  • They both have similar dye sites but nylon has many fewer dye sites than wool.

Basic Concepts of Nylon Production

• The first approach: combining molecules with an acid (COOH) group on each end are reacted with two chemicals that contain amine(NH2)groups on each end.

This process creates nylon 6,6, made of hexamethylene diamine with six carbon atoms and acidipic acid, as well as six carbon atoms.

• The second approach: a compound has an acid at one end and an amine at the other and is polymerized to for a chain with repeating units of(-NH-[CH2]n-CO-)x.
  • In other words, nylon 6 is made from a single six-carbon substance called caprolactam.
  • In this equation, if n=5, then nylon 6 is the assigned name. (may also be referred to as polymer)

Nylon 6,6

• Pleats and creases can be heat-set at higher temperatures

• Nylon is very easy to dye, but Nylon 6,6 is not

Nylon 6

• Better dye Affinity

• Softer Hand

• Greater elasticity and elastic recovery

• Better weathering properties; better sunlight resistance

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

• Variation of luster: nylon has the ability to be very lusterous, semilusterous or dull.
• Durability: its high tenacity fibers are used for seatbelts, tire cords, ballistic cloth and other uses.
• High elongation
• Excellent abrasion resistance
• Highly resilient (nylon fabrics are heat-set)
• Paved the way for easy-care garments
• High resistance to:
  • insects and fungi
  • molds, mildew, rot
  • many chemicals
• Used in carpets and nylon stockings
• Melts instead of burning
• Used in many military applications

Bulk properties

Above their quenched 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 tetrahedral bonds of singly-bonded carbon atoms.

When tensile strength.[2] 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 shearing electrode to prevent this.

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 absorbent than wool or cotton.

Historical uses

Bill Pittendreigh, 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.

Use in composites

Nylon can be used as the matrix material in composite materials, such as glass or carbon fiber, and yields a higher density than pure nylon.

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 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

• carpet fiber
• clothing
• fishing lines
• footwear
• nylon fiber
• pantyhose
• toothbrush bristles
• velcro
• airbag fiber
• auto parts: intake manifolds, gas (petrol) tanks
• slings and rope used in climbing gear
• machine parts, such as gears and bearings
• parachutes
• metallized nylon balloons
• classical and flamenco guitar strings
• paintball marker bolts
• racquetball, squash, and tennis racquet strings
• Strings for String instruments
• Drumstick heads
• As filter media in sterlizing grade filters
• Flexible tubing
• Basketball netting

See also

• Polymers
• Plastic
• Nylon 6
• Nylon 6-6
• Ballistic Nylon
• Rip-Stop Nylon
• Cordura
• Nylon riots

References