Nylon is
made through a complex two-step chemical and manufacturing process that first
creates the fiber’s strong polymers, then binds them together
to create a durable fiber. The term is commonly used to refer to a broad range
of polyamides, or synthetic polymers, and encompasses a range of often very
different products. Clothing, rope, hard plastic mechanical parts, parachute
coverings, and tires are all examples of the synthetic material in action. In
most cases the manufacturing process
is different for these different items, but the chemical part of their creation tends to be very similar.
Polymerization
The first thing the manufacturer must do is
to combine two sets of molecules. One set has an acid group on each end and the
other set has an amine group, made up of basic organic compounds, on each end.
There is some room for variation, but using hexamethylene diamine monomers and
adipic acid is a common combination. When these two substances are combined,
thick crystallized “nylon salts” result. These are commonly known as nylon 6, 6 or simply 6-6. The name is based on the number
of carbon atoms between the two acid groups and the two amine
groups.
This material can be chemically created in a different way as well,
namely by molding the same molecules into a different structure. In this
alternate method, the acidic molecules are all at one end of the structure, and
the amine molecules are all at the other. This compound is then combined into a
chain of carbon atoms. In either case, the crystals that result must be soaked
in water to dissolve them, then acidified and heated to create a chain that is
nearly unbreakable on a chemical level.
Heating and Spinning
Manufacturers typically use a
specially designed machine to get the polymers heated to the right temperature,
then combine the molecules to form a molten substance that is forced into aspinneret, separating it into thin strands and
exposing it to air for the first time. The air causes the strands to harden
immediately, and once they are hard they can be wound onto bobbins. The fibers
are stretched to create strength and elasticity, which is one of the material’s
main benefits.
From here the filaments are unwound
and then rewound onto another, smaller spool. This process is called drawing and is used to align the molecules
into a parallel structure. The strands that result are multipurpose threads
that can be used for a variety of different purposes. They can be woven or
bound as they are, or they can be combined and further melted.
Manufacturing Process
After the material has been wound onto the smaller spool, it is ready to
be turned into whatever product it is destined to become. From a technical
standpoint it is nylon at this point, but not in any form that consumers would
recognize, and it usually needs more refining in order for it to be useful in
the market.
Most products are created by weaving or fusing the filaments together.
Where materials and synthetic fabrics are concerned, the tighter the weave, the
stronger and more water resistant the material will be; for plastics and other
hard molded items, the hotter the temperatures for melting, the more seamless
and shiny the final product. Ropes and cording usually depend on complex
twisting and fusing, and most are actually made up of hundreds if not thousands
of individual strands bound together to create a very tough end product.
Nylon can also be mixed with other
fibers to create combination materials. When combined with cotton, it produces a resilient type of
fabric that holds its shape but is soft to the touch. It can also be woven into
patterns to reinforce strength, improve appearance, or meet other design
requirements. In industry and military uses it can be poured into molds and
used for machine parts, tire treads, and food storage containers, either in
isolation or in combination with other plastics and synthetic materials.
Nylon is a thermoplastic made from petrochemicals. It is a
semi-crystalline plastic, that it has both amorphous (unstructured) as well as
crystalline (structured) regions. When heat is applied it does not begin
to slowly melt like amorphous resins, rather it stays firm until it reaches its
melting point and then melts all at once. Nylon has a relatively high melting
temperature of 256°C/450°F.
Nylon is a tough material that is difficult to tear and exhibits
excellent abrasion resistance. It can bend and will bounce back. It
is not damaged by oils, solvents or alcohols. However, when exposed to acids
such as dilute sulfuric acid it will begin to break down. The material will
also be damaged if it comes into contact with phenols, alkalis, and
iodine. It is a hygroscopic material and on the molecular level tends to
absorb moisture from the surrounding environment. Water molecules bond with the amide groups
in the nylon molecules and cause the material to swell. At the same time,
nylon tends not to absorb water droplets from minor splashing, making it dry to
the touch. Nylon will decompose under sunlight so often UV resistance additives are used. Nylon is not affected by
fungi, molds and mildew and is not eaten by insects.
1) Plastic Fasteners and Machine Parts
Nylon is used for making plastic
machine parts as it is low cost and long lasting. It is often commonly used in
the electronics industry for its non-conductivity and heat resistance. It
is used for screws, bolts, washers and nuts as well as circuit board
hardware. Parts made of
nylon are often used in mechanisms that rotate or slide due its low
coefficient of friction. It is used to make bearings for the appliance industry
because of its excellent abrasion resistance.
2) Cookware
Nylon is used in cookware since it has
a relatively high continuous service temperature. These include spatulas,
slotted spoons, turners, forks, tongs, brushes, etc. Easy to dye, nylon
cookware can be color co-ordinated with kitchen decor. Nylon cooking tools are
gentle on non-stick surfaces. Companies such as OXO and Caphalon have used
nylon for their cookware products.
3) Fabric
Perhaps the most important
characteristic of nylon is that it can be made into strong fibers. When these
are woven together a silky, lightweight fabric is produced. Nylon was introduced as a fabric during the
1939 New York World’s Fair and by 1940 was used to make women’s
stockings. Nylon fabric became important as a synthetic substitute for
silk in the manufacture of parachutes when silk became scarce during
WWII. Nylon is still used today to make parachute canopies due to its elasticity, strength, resistance to mildew, availability
and price. However, the use of nylon fibers does not stop with the
fabric. Harness straps and suspension lines are also made from nylon
fibers as well as tents, sleeping bags, sails, rope, tennis strings, fishing
poles and lines, etc.
Today nylon is the most common fiber for textiles and it is one of the strongest and
most common fabrics on the market. It can be easily dyed so textiles can be
made in a rainbow of colors. It is known to drape well and is used extensively
in apparel. Nylon fabric is used in an almost countless number of items: book
bags, back packs, flak jackets, wedding gowns and bridal veils, athletic shoes,
ponchos, umbrellas, camera cases, swimsuits, socks, gloves, hats, luggage, and
much more.
Sample products:
Weaving nylons
into patterns makes it stronger and enables the manufacture of products such as
nylon rope.
Umbrellas are made from nylon.
Stocking and hosiery are commonly made of nylon.
Some cold weather sweaters are made from synthetic wool.
