The chemical name of Nylon is polyamide. The English name polyamide (PA) is also a term for polyurethane fiber, which is nylon – the world’s first synthetic fiber. It is a general term for thermoplastic resins containing repeating amide groups on the main chain of the molecule. Therefore, there are many types of nylon and it does not refer to only one substance. This also includes aliphatic PA, aliphatic-aromatic PA and aromatic PA. Among them, aliphatic PA has many varieties, large output and wide application, so its naming is determined by the specific number of carbon atoms of the synthetic monomer
2. Development process
The research on the synthesis of polyamide can be traced back to 1928. In 1935, when the American scientist Carothers and his collaborators were conducting theoretical research on the polycondensation reaction, they used adipic acid and adipic acid in the laboratory. The amine produces the high molecular weight linear condensation polymer polyhexamethylene adipamide (polyamide 66). From 1936 to 1937, the American DuPont Company used melt spinning to make polyamide 66 fiber based on Carothers’ research results, and named the fiber product nylon. This was also the first polyamide variety, which was produced industrially in 1939. In addition, Schlack of Germany invented the synthesis of polycaprolactam (polyamide 6) using caprolactam in 1938 and its fiber production technology, which was industrialized in 1941.
After more than half a century of development, many polyamide products have been introduced one after another. Aliphatic polyamides (PA) include PA-6, PA-610, PA-612, PA-1010, PA-11, PA-12 and PA-46, etc. Aromatic polyamides include poly-phenylene terephthalamide fiber, which is commonly known as aramid 1414 in my country, and poly-phenylene isophthalamide fiber (aramid 1313 in my country). Hybrid polyamides include polym-phenylene adipamide (MXD16) and polyhexamethylene terephthalamide (polyamide 6T).
3. Characteristics of nylon
1.
It has excellent mechanical properties, high mechanical strength and good toughness. As a synthetic fiber, the most prominent advantage of nylon is that its wear resistance is higher than that of all other fibers. It is 10 times more wear-resistant than cotton and 20 times more resistant than wool. Adding some polyamide fiber to the blended fabric can greatly improve its wear resistance. Wear resistance; when stretched to 3-6%, the elastic recovery rate can reach 100%; it can withstand tens of thousands of bends without breaking.
2. It has excellent self-lubricating properties and good friction resistance. Nylon has good self-lubricating properties and small friction coefficient.
3. It has excellent heat resistance and excellent weather resistance.
4. It has excellent electrical insulation properties. Nylon has high volume resistance and high breakdown voltage resistance. It is an excellent electrical and electrical insulation material.
5.
It is water-absorbent, and nylon is highly water-absorbent, which can easily lead to changes in the size and performance of the product. However, there are terminal amino groups and carboxyl groups at the end of the main chain of polyamide macromolecules, which have certain reactivity under certain conditions. Therefore, chemical and physical modifications can be carried out through methods such as blocking, grafting, blending, reinforcement and filling to overcome the changes in size and performance caused by greater water absorption.
4. Applications of Nylon
There are two main applications of nylon. In its early days, it was mainly used as a textile raw material. This can be seen from the word nylon in many of our clothing labels. During World War II, because nylon was often used in paratrooper parachutes, military uniforms and other war preparation supplies, nylon stockings, a favorite item among women, became a rationed item. As a result, its price soared, so that poor women at the bottom had to use pens to She drew seams on her legs that resembled the seams of nylon stockings to make them look real, and jokingly called them “magic stockings.”
On the other hand, nylon is not only non-toxic and lightweight, but also has excellent mechanical strength, good wear resistance and good corrosion resistance. So nylon was used to make engineering plastics in the early 1950s to replace steel, iron, copper and other materials. Therefore, nylon engineering plastics are often used to make wear-resistant parts, transmission structural parts, household appliance parts, automobile manufacturing parts, screw preventive mechanical parts, chemical machinery parts, and chemical equipment. Such as turbines, gears, bearings, impellers, cranks, instrument panels, drive shafts, valves, blades, screw rods, high-pressure washers, screws, nuts, seals, shuttles, sleeves, sleeve connectors, etc.
