Nylon PA
Polyamide fiber is the first synthetic fiber produced in the world. The word nylon is used as a general name for polyamide fibers. Nylon fiber was first used in the production of women's socks.
There are two types of polyamide fibers most produced and consumed. These are nylon6.6 and nylon 6.
Nylon 6.6
The starting materials of Nylon 6,6 are adipic acid and hexamethylene diamine. There are 6 carbon atoms each in adipic acid and hexamethylene. The first process to obtain nylon 6.6 fiber is to enable these two substances to form long molecular chains or polymers. When these starting materials are heated in ethyl alcohol, the nylon 6.6 salt is formed. When the solution of this salt in water is kept at 215 – 220 °C in an airless environment by giving steam under pressure, polymerization begins.
When the degree of polymerization reaches the desired level, 1% acetic acid is added and polymerization is stopped. Nylon 6.6 polymer, which is milky white and solidifies, is cut into small pieces and turned into filaments according to the soft spinning method. These filaments are then subjected to a stretching process. If nylon 6.6 filaments are to be obtained as matte, 6.6% TiO1 is added in the form of nylon 2 salt.
Physical Properties of Nylon 6.6 Fiber
1-Cross-section and longitudinal view: Nylon 6.6 fibers have the appearance of a smooth cylinder, a glass rod under the microscope. Its cross section is round.
2-Color and BRIGHTNESS: Nylon 6.6 fibers are glossy, can be obtained as semi-matt or matte by adding titanium dioxide (TiO2) if desired.
3-Thinness and LENGTH: Nylon 6.6 fibers can be produced in various lengths. Depending on the area of use, they can be in filament form or in staple form.
4-Strength: The strength of nylon 6.6 fibers is very high. The strength of nylon 6.6 fibers is between 4.5 – 6 gr/denier in dry form and between 4.1 – 5.2 gr/denier in wet state. There is a slight decrease in strength when wet.
5-Moisture absorption feature: Nylon 6.6 fibers have lower moisture absorption properties than natural fibres. This rate varies between 4 – 4.5% under normal conditions.
6-Rubbing resistance: Nylon 6.6 fibers have a very good resistance to friction. However, lint problem can be encountered.
7-Dimension invariance: Nylon Dimensional stability of 6.6 products is good when washed at low and warm temperatures. Products washed at high temperatures shrink due to shrinkage.
8-Flexibility and springiness: Nylon 6.6 fibers have high flexibility and good springiness. Nylon 6.6 fibers can return to their original state when extended by 8%. The elongation rate of Nylon 6.6 fibers in filament varies between 26% – 32% in dry state and 30 – 37% in wet state.
9-Volumetric density : Nylon 6.6 fibers are a very light fiber with a specific weight of 1.14 gr/cm³.
Chemical Properties of Nylon 6.6 Fiber
1- Being affected by chemical substances: Nylon 6.6 fibers are resistant to chemicals. While aqueous acids do not have a negative effect on the fibers, strong acids such as sulfuric acid and nitric acid break down the fiber. Hot and cold hydrochloric acid damage the fiber. It is highly resistant to alkalis. Except for phenol, cresol and formic acid used in dry cleaning, other solvents do not harm the fiber.
2-Resistance to environmental factors: Nylon 6.6 fibers are resistant to sunlight. However, if they are exposed to sunlight for a long time, their strength will decrease slightly. Bacteria, fungi, moths and other harmful insects do not damage the fibers.
3-Electrification feature: Nylon 6.6 fibers are charged with static electricity since their electrical conductivity is very poor. Since its electrical conductivity is very low, fibers are also used for insulation purposes in electrical materials.
4-The ability to be affected by heat: Nylon 6.6 fibers turn yellow at 150 °C. It softens at 230 °C. The melting point of nylon 6.6 fibers is around 260 °C.
5-Burning feature: Nylon 6.6 fibers do not ignite immediately when it encounters a flame, but when it starts to burn, it burns with a flame. Due to its thermoplastic feature, the fibers first soften and then melt by dripping. The ash is cream-colored, bead-shaped and hard.
Usage Areas of Nylon 6.6 Fiber
Nylon 6.6 fibers are used in many areas such as clothing, interior upholstery fabrics and industrial textiles.
Clothing : Dress, swimwear, sportswear, women's, men's and children's socks, underwear, jackets and shirts.
Home textiles: Bed linen, carpet and drapery fabrics.
Industrial areas: It is used in tents, sleeping bags, fishing nets, umbrella and parachute fabrics, automobile tires and seat belts.
Nylon 6
It is the second most produced type among polyamide fibers. Nylon 6 fibers were produced in Germany in 1940 with the trade name Perlon L. Produced nylon 6.6 fibers and nylon 6 fibers meet all nylon fiber needs.
Obtaining Nylon 6 Fiber
Nylon's starting material is 6 carbon amino caproic acid NH2(CH2)5 COOH. This material is polymerized at 260 °C under pressure using nylon 6.6 salt as catalyst. Nylon 6 polymer is melted at 220 °C and turned into filament by soft spinning method. These filaments are then subjected to a stretching process to increase their strength.
Physical Properties of Nylon 6 Fiber
1-Cross-section and longitudinal view: Nylon 6 fibers have the appearance of a smooth cylinder, a glass rod under the microscope. Its cross section is round.
2-Color and shine: Nylon 6 fibers are glossy, if desired, it can be obtained as semi-matt or matte by adding titanium dioxide (TiO2).
3-Thinness and length: Nylon 6 fibers can be produced in various lengths. Depending on the area of use, it can be in the form of filament or in the form of staples.
4- Resistance: The strength of nylon 6 fibers is slightly higher than nylon 6.6. The strength of nylon 6 fibers is between 4.5 – 7 gr/denier in dry condition and 4.1 – 6 gr/denier in wet state. There is a slight decrease in their strength when wet.
5-Moisture absorption feature: Nylon 6 fibers have lower moisture absorption properties than natural fibers. It shows the same feature as nylon 6.6 fibers. This rate varies between 4 – 4.5% under normal conditions.
6-Rubbing resistance: Nylon 6 fibers have very good resistance to friction.
7-Dimension invariance: Nylon Dimensional stability of 6 products is good when washed at low and warm temperatures. Products washed at high temperatures shrink due to shrinkage.
8-Flexibility and springiness: Nylon 6 fibers have high flexibility and good springiness. Nylon 6 fibers can return to their original state when extended by 8%. The elongation rate of Nylon 6 fibers in filament varies between 23-43% in dry state and 27-34% in wet state.
9-Volumetric density: Nylon 6 fibers are a very light fiber with a specific weight of 1.14 gr/cm³.
Chemical Properties of Nylon 6 Fiber
1-Affected by chemical substances: Nylon 6 fibers are resistant to chemicals. While aqueous acids do not have a negative effect on the fibers, strong acids such as sulfuric acid and nitric acid break down the fiber. Hot and cold hydrochloric acid damage the fiber. Its resistance to alkalis is better than nylon 6.6. Except for phenol, cresol and formic acid used in dry cleaning, other solvents do not harm the fiber.
2- Resistance to environmental factors: Nylon 6 fibers have lower resistance to sunlight. If they are exposed to sunlight for a long time, their strength will decrease. Therefore, it is not recommended to be used as a curtain fabric. Bacteria, fungi, moths and other harmful insects do not damage the fibers.
3-Electrification feature: Nylon 6 fibers are charged with static electricity since their electrical conductivity is very poor. Since its electrical conductivity is very low, fibers are also used for insulation purposes in electrical materials.
4-The property of being affected by heat: The melting point of nylon 6 fibers is lower than nylon 6.6 fiber and is around 215 °C.
5-Burning property: Nylon The 6 fibers do not ignite immediately when it encounters a flame, but when it starts to burn, it burns with a flame. Due to its thermoplastic feature, the fibers first soften and then melt by dripping. The ash is cream-colored, bead-shaped and hard.
Usage Areas of Nylon 6 Fiber
Although the usage areas are similar with nylon 6.6 fibers, there are points where they differ due to some properties. Since the melting points are different, the ironing temperature to be applied is also different. Although the moisture wicking properties are the same, nylon 6 fiber is easier to use in some paints.
Brighter and more vivid colors can be obtained by dyeing. It is not used in curtain construction as it has less resistance to sunlight. Since the handle of nylon 6 is softer than nylon 6.6, it is mostly used in knitwear and in the production of textured yarns.
Clothing: Dress, women's, and children's socks, underwear, shirts
Home textiles: Bed linen, carpet making
Industrial areas: It is used in tents, fishing nets and automobile tires.
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