Introduction
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- Polyamides are polymers whose monomeric units are joined by the amide (-NH-CO-) linkage (at least 85%).
- There are aliphatic or cyclo-aliphatic units, often known as nylons.
- Polyamide is synthesized by a condensation reaction between diamine and diacid, where the repeating units are held together by amide links.
- In 1939, USA's first polyamide was produced by adipic acid and hexamethylene diamine named polyamide 66.
- IN 1938, German caprolactam was polymerized as polyamide 6 (Nylon 6).
Synthesis of Nylon 66
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| Synthesis of Nylon 66 ©Textile Pad |
Synthesis of Nylon 6
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| Synthesis of Nylon 6 ©Textile Pad |
Extrusion of Nylon
- Polyamide fibers/filaments are melt SPG.
- Dry N2 is used to prevent oxidation.
- Extrusion temperature Nylon 66 (280- 290℃), Nylon 6 (250-270℃).
- Spinneret holes dia 0.1-0.4 mm.
- Extrusion velocity is normally 1000-1200 meters/min.
- After extrusion, it passes through a cooling chamber almost 5 meters long.
- The filaments are then moisturized through steam or spin finish to absorb a small amount of water (MR% 4.0-4.5).
- Then the filaments are drawn at a draw ratio of 4-5 in the cold drawing method for apparel used and carpets.
- Stronger yarns are required to demand application drawn at a higher temperature, then texturized, and finally heat set.
- Heating-Nylon 66 (180-200℃)-Nylon 6 (160-180℃) in presence of steam.
- Induces the annealing process.
- Estimated polymer 90-140 nm length.
- Estimated polymer thickness of 0.3 nm.
Properties of Nylon
End Uses of Nylon
- Swimwear, skiwear, sportswear, lingerie.
- Extensively used as carpet fibers.
- Wool/Nylon (80:20) blend.
- High-tenacity tire cord, adhere to rubber.
- Reinforced rubber in drive belts, and conveyor vehicle airbags.
Tags
Synthetic Fibers