Teflon Rod (PTFE Ploytetrafluoroethylene
Sand Graphite and Glass Filled)
Plastics & Nylon
PA6E / PA6G Polyamides / GPolyacetal POM / ALPolyethylene Terephthalate PET /
UHMWPE Polyethylene PETKG ® polypropylenes PP PPPolyvinyl chloride PVC VINYL /
Teflon & Nylon Sheets
Teflon® is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene.
3D model of a section of PTFE
Polytetrafluoroethylene (PTFE) is a fluoropolymer discovered by Roy J. Plunkett (1910–1994) of DuPont in 1938. It was introduced as a commercial product in 1946 and is generally known to the public by DuPont's brand name Teflon®.
PTFE has the lowest coefficient of friction (against polished steel) of any known solid material. It is used as a non-stick coating for pans and other cookware. PTFE is very non-reactive, and so is often used in containers and pipework for reactive chemicals. According to DuPont its melting point is 327 °C, but its properties degrade above 260 °C.
Other polymers with similar composition are known with the Teflon® name: fluorinated ethylene-propylene (FEP) and perfluoroalkoxy polymer resin (PFA). They retain the useful properties of PTFE of low friction and non-reactivity, but are more easily formable. FEP is softer than PTFE and melts at 260 °C; it is highly transparent and resistant to sunlight.
Properties and applications
Amongst many other industrial applications, PTFE is used to coat certain types of hardened, armour-piercing bullets, so as to reduce the amount of wear on the firearm's rifling. These are often mistakenly referred to as "cop-killer" bullets by virtue of PTFE's supposed ability to ease a bullet's passage through body armour. Any armour-piercing effect is, however, purely a function of the bullet's velocity and rigidity rather than a property of PTFE.
PTFE has excellent dielectric properties. This is especially true at high radio frequencies, making it eminently suitable for use as an insulator in cables and connector assemblies and as a material for printed circuit boards used at microwave frequencies. Combined with its high melting temperature, this makes it the material of choice as a high performance substitute for the weaker and more meltable polyethylene that is commonly used in low-cost applications. Its extremely high bulk resistivity makes it an ideal material for fabricating long life electrets, useful devices that are the electrostatic analogues of magnets.
Due to its low friction, it is used for applications where sliding action of parts is needed: bearings, bushings, gears, slide plates, etc. In these applications it performs significantly better than nylon and acetal; it is comparable with ultra high molecular weight polyethylene (UHMWPE), although UHMWPE is more resistant to wear than Teflon®. For these applications, versions of teflon with mineral oil or molybdenum disulfide embedded as additional lubricants in its matrix are being manufactured.
Because of its chemical inertness, PTFE cannot be cross-linked like an elastomer. Therefore it has no "memory", and is subject to creep (also known as cold flow and compression set). This can be both good and bad. A little bit of creep allows PTFE seals to conform to mating surfaces better than most other plastic seals. Too much creep, however, and the seal is compromised. Compounding fillers are used to control unwanted creep, as well as to improve wear, friction, and other properties.
Gore-Tex is a material incorporating Teflon® membrane with micropores. The roof of the Hubert H. Humphrey Metrodome in Minneapolis is the largest application of Teflon® on Earth, using 20 acres of the material in a double-layered white dome, made with PTFE-coated fiberglass, that gives the stadium its distinctive appearance.
Powdered PTFE is used in pyrotechnic compositions as oxidizer together with powdered metals such as aluminum and magnesium (see Magnesium/Teflon/Viton). Upon ignition these mixtures form carbonaceous soot and the corresponding metal fluoride and release large amounts of heat. Hence they are use as infrared decoy flares and igniters for solid fuel rocket propellants.
Electrical conductivity (σ)
463 K-624 K
represents a family of synthetic polymers, a thermoplastic material, first
produced on 28 February, 1935 by Gerard J. Berchet of Wallace Carothers'
research group at DuPont. The first product was a nylon-bristled toothbrush
(1938), followed more famously by women's 'nylons' stockings (1940). It is made
of repeating units linked by peptide bonds (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 monomers 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 parachutes 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 fabrics and ropes, and solid nylon
is used for mechanical parts 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.
Above their melting temperatures, Tm, thermoplastics like nylon are amorphous solids or viscous fluids in which the chains approximate random coils. Below Tm, amorphous regions alternate with regions which are lamellar crystals. The amorphous regions contribute elasticity and the crystalline regions contribute strength and rigidity. The planar amide (-CO-NH-) groups are very polar, so nylon forms multiple hydrogen bonds 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 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 carbonyl oxygens and amide hydrogens can line up to form interchain hydrogen bonds 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 feathers. (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 rotations 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. 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 stresses during formation. Nylon is clear and colorless, or milky, but is easily dyed. Multistranded nylon cord and rope is slippery and tends to unravel. The ends can be melted and fused with a flame to prevent this.
There are carbon fiber/nylon composities with higher density than pure nylon.
Bill Pittendreigh, Dupont industries, 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 parachutes. It was also used to make tires, tents, ropes, ponchos, 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.
Some people, such as Jack Herer, surmise that Cannabis sativa was made illegal because the fibers from the hemp plant, used for fabrics and ropes, were in strong competition with nylon (along with paper, fuel, and other industries). While the production of rope from hemp requires no chemicals or industrial processes, nylon fiber is more than twice as strong as hemp and weighs 25% less. An additional problem is that hemp rope rots from the inside out, making it difficult to determine the condition of a rope at a glance. While hemp was originally used in climbing rope, this is no longer the case, even in countries where cannabis is legal.
• nylon fiber
• toothbrush bristles
• fishing lines
• carpet fiber
• airbag fiber
• auto parts: intake manifolds, gas (petrol) tanks
• slings and rope used in climbing gear
• machine parts, such as gears and bearings
• metallized nylon balloons
• classical and flamenco guitar strings
• paintball marker bolts
• racquetball, squash, and tennis racquet strings
• Chompy Strings
• Guitar Strings