Nylon is a polyamide plastic. So it is made up of two monomers. Each monomer contains 6 carbon atoms of hexamethylenediamine and six of adipic acid.
FIVE REASONS NOT TO USE NYLON
HYGROSCOPIC
This plastic is hygroscopic. That means it absorbs water even from the natural environment. And water absorbsion can cause changes in a part’s dimensions.
NOT UV RESISTANT
It is not UV resistant without additives.
NOT CHEMICALLY RESISTANT
And this polymer is not particularly chemically resistant as it performs poorly in acids and halogens. It does slightly better in ketones and hydrogenated hydrocarbons. However, it is not suggested for use in the presence any of these chemicals.
LOW CONTINUOUS SERVICE TEMPERATURE
It has a relatively low continuous service temperature of 223 degrees F. Thus it is not recommended for use in ovens or in boiling water.
NOT HIGH STRENGTH
And it is not high strength with an ultimate tensile strength of 10,000 psi. Although this is not bad, FRP/G10 has a UTS of 45,000 PSI.
POPULARITY OF NYLON
But Nylon is one of the most popular plastics in use. So why is this? First of all, it is used extensively in the building of automobiles to help with greater fuel efficiency. And it is used in fiber for fabrics from stockings to parachute fabric as well as tents and rope. This plastic accounted for about 30 billion USD in the plastic industry in 2020. About a third was used in the automotive industry. Also one quarter was consumed for products such as nylon fasteners and custom parts. It is also used in the textile industry as well as the electrical and electronics industries. The most common grades are Nylon 6/6, 6, 4/6 and 612.
CHARACTERISTICS
NYLON AS AN INSULATOR
Importantly, it is an insulator. Its electrical resistivity is 1500 V/mil. This makes this plastic useful in electrical applications and electronics. Nylon fasteners made for these applications are screws, hex nuts, washers, cable ties, spacers, standoffs, screw insulators, parts for printed circuit boards including panel fasteners, snap rivets, and grommet nuts. It is also used for threaded rod, custom parts and thousands of other fasteners.
NYLON IS HYGROSCOPIC
Although it is hygroscopic, it is water repellent. Water repellent means a material is able to resist water penetration but not completely. But water repellence is all that is needed in many applications. For example in the automotive industry. Although parts of a car might get wet, usually they will dry off fairly quickly. This is the same for things made from nylon fibers. And usually, these products are not made to tight tolerances.
NOT NATURALLY UV RESISTANT
The lack of UV resistance can be a problem. If a product made from nylon receives UV rays continually it may cause it to fall apart. Say like a summer folding chain made of nylon webbing. However, the material can be treated with UV stabilizers. This will effectively stop deterioration from the sun. Also, some applications will never be exposed to the sun’s rays. For example, it is used extensively for indoor carpets. UV resistance can also be important in engineered plastic applications such as nylon fasteners that are exposed to UV rays.
GASOLINE IS A HYDROCARBON WHILE KEROSENE IS A MIXTURE
This material does well in gasoline and kerosene. This is not surprising since this polymer is derived from petrochemicals. Nylon 6 is used in car engine components such as bushings, oil containers, crankcases, cylinder head covers, and much more. Nylon 612 has been used in fuel line applications.
WEAR RESISTANT
It also has good wear resistance. It is also possible to add molybdenum disulfide to the material to improve lubricity. This is important in the engineered plastics industry for bushings and bearings.
LOW CONTINUOUS SERVICE TEMPERATURE
It does however have a relatively low continuous service temperature of 223 degrees F. This is low for an engineered plastic. However, this can be enough for a particular application. In automobiles, nylons are used in headlamp bezels, wheel covers, fuel caps, tailgate handles, front-end grilles, and exterior mirrors. Also it is used to make fabric for clothes, stockings, rope, and tents. These will all perform well with its continuous service temperature.
DOES NOT BURN
Its flammability rating is UL 94V-2. So it tends to melt rather than burn which is useful in many applications.
USEFUL IN BREAKAWAY APPLICATIONS BUT CAN BE MADE STRONGER
Nylon is not the strongest plastic available. But it is useful in applications where a part is designed to break away at a certain load. If strength is required adding glass fiber to the resin will result in a tensile strength of 32,000 psi. This is approximately 200 times that of the base resin.
REPLACEMENTS FOR NYLON
Nylon use is expected to grow in the coming years. But there are other less expensive materials that can perform well in the required applications. Some even perform better. Also such plastics as polypropylene, Polyvinylidene Fluoride (PVDF), and para-aramid synthetic fibers are an increasing threat to the use of nylons.
