Nylon is a generic name given to a group of related compounds classified as Polyamides, just like cotton, linen and wool. Nylon is a long chain of linear con-centrated polymer made from haxamethy-lene diamine and adipic acid. Nylon is the first synthetic fibre made in 1928 during a research at Dupont Company.
Nylon was invented by E.I.Du Pont de Nemours & Co. The credit of the dis-covery of the nylon goes to Dr.Wallace H. Carothers and his staff of organic chem-ists who worked in Du Pont’s chemi-cal department. Realizing that there is a need of more active program of research to provide new developments, Du Pont began a long range of programme in 1928. Du Pont now shifted from applied research to fundamental research, which primarily aimed to develop knowledge of chemicals, materials and processes.
After many months of research, Dr.Carothers assistant discovered a poly-mer, which was a clear, heavy molasses when molten and could be drawn out into filament. This was a polymer. It was called 6.6, because there were six carbon atoms per molecule. Later it was called Nylon. It is also known a polyamide.
Nylon is actually a group of related chemical compounds. It is composed of hydrogen, nitrogen, oxygen and carbon in controlled proportions and structural arrangements. Variations in the chemi-cal structures can result in formation of compounds like plastic. The two types of nylon are nylon 6.6 and nylon 6.
The diameter of the nylon yarn filament can be determined by the rate of delivery from the pump to the spinneret and the rate by which the yarn is drawn away from the spinneret. The size of yarn, which is measured in denier, can be determined by the diameter and the number of filaments in the yarn. Based upon this nylon can be divided as Nylon 6.6, Nylon 6.12, Nylon 4.6, Nylon 6, Nylon 12 and so on.
· Monofilament Yarns.
· Multifilament Yarns.
· Stretch Yarns.
· Textured Yarns.
· Spun Yarns.
Required amount of hexamethylene diamine and adipic acid are mixed to form nylon salt. This salt is dissolved in water at the spinning mill and heated to get a con-centrated nylon salt solution. The solution is placed in an autoclave under high pressure and heat which results in giant chain links structure called “Linear Superpolymers”. The solution is slowly passed over the auto-clave and a molten nylon resin is deposited on wheel. This is sprayed with cold water to harden into opaque ribbon, flakes or pellets. On melting this pellets or flakes are passed through the spinneret to form nylon yarns (Figure 3.3).
Shape : Can be modified as per requirement.
Size : Thin long filament.
Density : 1.1 g / ccm
Lustre : Varies from brightness to dullness
Strength : Good
Elongation : Good
Elastic recovery : 100%
Resiliency : Good
Moisture absorption : 8%
Dimensional stability : Excellent
Resistance to acid : Poor
Resistance to alkalies : Good
Sunlight : Affected by sunlight
Insects : Normally damages the fibres
Resistance to flame : Self extinguishing
Nylon fabrics can be given various finishes.
Antistatic finish : For reduction of electrostatic build up
Embossing : For patterns or designs
Heat setting : For permanent shape
Moireing : For shimmer effect
Molding : For shaping fabrics
Nylonizing : For increased absorbency
Water repellence : For added protection against water
Dyeing : For imparting colour to the fabric
· Nylon is used in women’s stockings or hosiery. It is also used as a mate-rial for producing socks, swimwear, shorts, track pants, active wear, draperies and bedspreads.
· Nylon is used for making fishing nets, ropes, parachutes and tyre cords.
· Nylon is used in cookware since it has a relatively high continuous ser-vice temperature.
· 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.