Polyamide (6,6) is the most commonly used nylon material in the world
Polyamide (6,6) is the most commonly used nylon material in the world
Dr. Adil S. Matuk- Department of physics
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Nylon is one of the most versatile materials known to man, capable of being molded into commercial or industrial products or being drawn into fibers for the textile industry. Everywhere one looks, they can find nylon; toothbrush bristles, nylon-blended clothing, nylon umbrellas, nylon gears for different gadgets, and much more.
Polyamide is the chemical name for the general term ‘nylon’. Polyamide 6,6 (or equivalently, Nylon 6,6) is the most commonly used nylon material in the world along with Nylon 6. Nylon materials, and especially Nylon 6,6, are used for their unique blend of properties which include but are not limited to: (1) high mechanical strength, (2) rigidity, (3) high heat resistance, (4) high chemical resistance, and (5) relatively low thermal expansion.
Nylon 6,6 has found a lot of application in the fiber/textile industry from everything from guitar strings, for their elasticity and excellent tensile strength (as well as their musical sound), to precision molded plastic parts that can often replace ceramics and metals in applications typically thought not reasonable for a polymer. The reasons for which a polymer might not be considered suitable for a given application usually include heat issues (high temperature applications) or strength issues. The properties of nylon are very unique to the material which is why it is the main alternative to silks, cloths, and hemp in each of their respective applications (at times even outperforming the latter).
One of the most attractive properties of nylon 6,6 (and nylons in general) is its chemical resistance. Due to the formation process for nylon 6,6 it is extremely difficult for any foreign agents to compromise the nylon structure. Nylon 6,6 is made of thousands of individual strands of materials bonded together physically by hydrogen bonding. These strands can form parallel to each other and align themselves so that the intermolecular forces of attraction are maximized, this means that it is very difficult to interfere with the molecular structure of the material, and as such very difficult for foreign agents to compromise the material. The term ‘foreign agents’ can refer to everything from mold, fungus, insects, and water. This is the reason for nylon’s use in outdoor fiber applications such as umbrellas or swimming outfits. Nylon braided rope, in addition to being incredibly strong, is often left at hook-up sites for would be climbers or hikers because of the fact that it won’t degrade very much due to any weather conditions.
The water molecules cannot penetrate the nylon and neither can they effectively wet the nylon, making it fantastic for commercial outdoor products and industrial applications where dampness or mold might compromise another material. Although the chemical resistance is excellent, nylon is not invincible as it is susceptible to phenol, relatively strong acids, and some other uncommon materials which are unlikely to be found in commercial applications. Also, prolonged exposure to water will eventually lead to wetting, although it is less absorbent than wool or cotton.
Although nylon is a thermoplastic material, meaning that melts and begins to flow beyond a certain temperature, the temperature at which this occurs is relatively high for polymer materials. This begins to occur for nylon 6,6 at roughly 260°C (500°F). The significance of this is that the nylon material can be used at higher temperature applications than other thermoplastic materials. In general, most thermoplastics will begin to melt somewhere below 170°C. The higher temperature of nylon 6,6 and nylon 6 make it a reasonable choice for an alternative to ceramic or metal parts in vehicles and machinery. As an example, several parts of the engine and break mechanics of a typical car (the two areas where the temperature and friction would be highest) are made of nylon 6,6. Looking under the hood of a vehicle will reveal that much of it is plastic including all of the tubing and a lot of brackets which are majority nylon 6,6.
The mechanical properties, meaning tensile strength and rigidity, of nylon are also a major selling point for the material. Nylon is a major component in the fiber and textile industries because of its impression tensile strength. Nylon, by itself, is stronger than cotton, silk, or hemp. Clothes containing nylon fibers are also extremely abrasion resistant as well as elastic. Nylon can completely reform to its original configuration regardless of wrinkling or stretching so long as an elongational strain is maintained below roughly 10%. Nylon is often used in those areas of clothing that are subject to the most stress/strain (e.g. shirt necks, sock necks, knees in most leg apparel, and elastic waistlines).
Nylon 6,6 and other nylons have very unique properties that are accentuated in each of their many versatile applications. Nylon can be used for: (1) high mechanical strength, (2) rigidity, (3) high heat resistance, (4) high chemical resistance, (5) elasticity and flexibility in fibers, and (6) relatively low thermal expansion. Some applications, as mentioned above, also use several of those aspects in conjunction with another to improve the performance of the material as a whole.