NYLON-6: POLYMERIZATION CHEMISTRY, PROPERTIES, AND INDUSTRIAL APPLICATIONS –AN INDUSTRIAL REVIEW
DOI:
https://doi.org/10.53555/m2hyw924Keywords:
Fibre Formation, Melt Spinning Nylon-6, Polymerization and Process Control, Technical Textile, Fibre PropertiesAbstract
Nylon-6, a widely used polyamide, stands out among synthetic polyamides as a versatile, high- performance fibre owing to its unique macromolecular structure, balanced physicochemical properties, and broad processability. It is synthesized by the ring-opening polymerization of ε- caprolactam through hydrolysis, polyaddition, and polycondensation under controlled thermal and pressure conditions. The polymerization process is critical in defining the final polymer’s characteristics, including molecular weight distribution, residual monomer content, and relative viscosity, which directly influence fiber-forming capability. Advanced process control systems regulating temperature, pressure, level, and flow are indispensable for ensuring stability, reproducibility, and energy efficiency at industrial scale. The structural property relationship of Nylon-6 highlights its superior tensile strength, elasticity, abrasion resistance, dyeability, and thermal stability (Tm ≈ 220°C),with crystallinity levels around 50–55%. Post-polymerization treatments, such as hot washing and solid-state aging, further improve viscosity control and spinnability. Modified formulations with additives or resin blends enhance resistance to heat, solvents, and fire, expanding its range of applications. Due to this combination of mechanical robustness and processability, Nylon-6 is extensively employed in technical textiles (tire cords, carpets, fishing nets, parachutes, and sutures), apparel fabrics, packaging films, and engineering plastics processed via injection molding, extrusion, and blow molding. This Industrial Case study consolidates polymerization principles, control strategies, material properties, and applications of Nylon-6, providing a comprehensive perspective for advancing both research and industrial practices.
References
1.(P.Schlack) IGFarbenindustrie, “IGFarbenindustrie,(1941)US2241321(P.Schlack),” 1941.
2.L. Deopura, “Polyamide fibers,” Polyesters and Polyamides, pp. 41–61, 2008, doi: 10.1533/9781845694609.1.41.
3.J. Carothers, “Carothers,W.H.(1929)J.Am.Chem.Soc.51,2548–2559.,” 1929.
4.“Nylon 6 - an overview | ScienceDirect Topics.” Accessed: Aug. 22, 2025. [Online].
5.Available: https://www.sciencedirect.com/topics/chemistry/nylon-6
6.Bhat and V. Kandagor, “Synthetic polymer fibers and their processing requirements,” in Advances in Filament Yarn Spinning of Textiles and Polymers, 2014, pp. 3–30. doi: 10.1533/9780857099174.1.3.P. Matthies and W. F. Seydl, “History and Development of Nylon 6,” pp. 39–53, 1986, doi: 10.1007/978-94-011-7073-4_4.
7.“U.S. Patent US20020183478 A1 — Process for converting caprolactam to nylon 6”.
8.L. W. Andrew. Massey, “Massey, LK, Permeability properties of plastics and elastomers:
9.a guide to packaging and barrier materials. 2003: William Andrew.,” 2003.
10.“Carothers,W.H.(1929)J.Am.Chem.Soc.51,2548–2559.”.
11.W. Andrew. McKeen, “McKeen, LW, Film properties of plastics and elastomers.
12.2017: William Andrew.,” 2017.
13.“BASF, (1980) US 4204049 (A), Hydrolytic Polymerization of Epsilon-Caprolactam.”.
14.“Heikens, D., Hermans, P.H. and Want, G.M.V.D. (1960) On the Mechanism of the Polymerization of ????-Caprolactam. IV. Polymerization in the Presence of Water and Either An Amine”.
15.L. K. Massey, “Nylon 6,” The Effects of UV Light and Weather on Plastics and Elastomers,
16.pp. 117–125, 2007, doi: 10.1016/B978-081551525-8.50024-5.
17.M. Sewidan, “Nylon-6 (polyamide 6), historical background, properties, limitations, and
18.applications.,” 2020.
19.“Japan Chemical Industry Association. Product Safety Summary: ε-Caprolactam. 2010.
20.Available at: JCIA Document”.
21.“AdvanSix Inc. Technical Data Sheet: ε-Caprolactam. 2023. Available at: AdvanSix TDS
22.PDF”.
23.“CN101885842B. Continuous Polymerization Production Technology for Polyamide Fibre
24.Chinese Patent, Publication Date: Dec. 15, 2010. Available at: https://patents.google.com/patent/CN101885842B/en (accessed Sept. 2025).”.
25.L. W. McKeen, “Polyamides (Nylons),” The Effect of Long Term Thermal Exposure on Plastics and Elastomers, pp. 139–170, 2014, doi: 10.1016/B978-0-323-22108-5.00007-2.
26.“Synthetic fibres: Nylon, polyester, acrylic, polyolefin.” Accessed: Aug. 25, 2025. [Online]. Available: https://www.researchgate.net/publication/296898681_Synthetic_fibres_Nylon_polyester_acrylic
27._polyolefin
28.N. Makul, “Nylon Fiber,” Dictionary of Concrete Technology, pp. 938–940, 2025, doi: 10.1007/978-981-97-2998-2_513.
29.W. H. Carothers and G. J. Berchet, “Studies on polymerization and ring formation. VIII. amides from ϵ-aminocaproic acid,” J. Am. Chem. Soc., vol. 52, no. 12, pp. 5289–5291, Dec. 1930, doi: 10.1021/JA01375A091.
30.P. Matthies and W. F. Seydl, “History and Development of Nylon 6 BT - High
31.Performance Polymers: Their Origin and Development,” pp. 39–53, 1986.
32.“Allied Chemical, (1967) CA 823290 (I.C. Twilley, D.W.H. Roth, Jr., R.A. Lofquist).”.
33.“Allied Chemical, (1968) US 3578640 (I.C. Twilley, G.J. Coll, Jr., D.W.H. Roth, Jr.).”.
34.L. K. Massey, “Nylon 6,” The Effects of UV Light and Weather on Plastics and Elastomers,
35.pp. 117–125, 2007, doi: 10.1016/B978-081551525-8.50024-5.
36.L. W. McKeen, “Polyamides (Nylons),” The Effect of Long Term Thermal Exposure on Plastics and Elastomers, pp. 139–170, 2014, doi: 10.1016/B978-0-323-22108-5.00007-2.
37.“Intratec. Nylon-6 Production from Caprolactam (Continuous Process). Intratec Solutions LLC, Technical Report Preview. Available at: https://cdn.intratec.us/docs/reports/previews/nylon- 6-e12a-b.pdf (accessed Sept. 2025).”.
38.W. H. Carothers and G. J. Berchet, “Studies on polymerization and ring formation. VIII. amides from ϵ-aminocaproic acid,” J. Am. Chem. Soc., vol. 52, no. 12, pp. 5289–5291, Dec. 1930, doi: 10.1021/JA01375A091.
39.“Handbook of Polymers | ScienceDirect.” Accessed: Aug. 25, 2025. [Online]. Available:
40.https://www.sciencedirect.com/book/9781895198928/handbook-of-polymers
41.“AlliedChemical,(1973)US3813366(W.H.Wright,A.J.Bing ham, W.A. Fox).”.
42.K. Agrawal and M. Jassal, “Manufacture of polyamide fibres,” Polyesters and Polyamides, pp. 97–139, 2008, doi: 10.1533/9781845694609.1.97.
43.K. Tai and T. Tagawa, “Review Section Simulation of Hydrolytic Polymerization of ∈- Caprolactam in Various Reactors. a Review on Recent Advances in Reaction Engineering of Polymerization,” Industrial and Engineering Chemistry Product Research and Development, vol. 22, no. 2, pp. 192–206, Jun. 1983, doi: 10.1021/I300010A007.
44.“Tai, K. and Tagawa, T. (1983) Ind. Eng. Chem. Prod. Res. Dev. 22 (2), 192–206.”.
45.“NIST Chemistry WebBook. Caprolactam – C6H11NO. National Institute of Standards and
46.Technology. Available at: NIST WebBook”.
47.“OSHA. Chemical Data for Caprolactam. Occupational Safety & Health Administration. Available at: OSHA Database”.
48.“Kohan,M.I. ed. (1973)NylonPlastics,Wiley-Interscience, NewYork.”.
49.“Matthies, P. andSeydl,W.F. History andDevelopment of Nylon6, inHighPerformancePolymers:TheirOriginand Development, (eds.R.B. Seymour andG.S.Kirshenbaum), Elsevier,NewYork,pp.39–53.”.
50.“Rothe, M. (1958) J. Polym. Sci. Part A: Polym. Chem. 30, 227. 185 Jacobs, H. and Schweigman, C. (1972) Mathematical Model for the Polymerization of Caprolactam to Nylon-6 in Chemi cal Reaction Engineering, Proc. Fifth Eur./Second Int. Sympos. Chem. React. Eng., Amsterdam, Elsevier, pp. B 7–1 to 7–26.”.
51.“Modelling of VK Column Reactors for Manufacturing Nylon-6. IJFTR, Vol. 20, Issue 3.
52.(Year).”.
53.“Global Journal of Researches in Engineering, Non-Linear Mathematical Modelling of Nylon-6 Polymerization in VK tube reactors. (2019).”.
54.“Plazl, I., & Krampe, D. (1998). Mathematical Model of Industrial Continuous Polymerization of ε-Caprolactam (Nylon-6). Industrial & Engineering Chemistry Research.”.
55.“Google Patents. US Patent: Nylon 6 Polymerization Reactor Temperature Control, 2022.”.
56.“Lurgi Zimmer GmbH, (2015) EP 2128198 (B1), Process for the Preparation of Polyamides Using Carboxylic Acids and Amides.”.
57.“Technip Zimmer GmbH, (2017) WO 2017054957 (A1), Method and Device for Continuously Modifying a Polymer Melt Made of Non-extracted Polyamide 6 with One or More Additives.”.
58.“Allied Chemical, (1980) EP-A 0038473 (S.L. Yates, C.J. Cole, A.H. Wiesner, J.W.
59.Wagner).”.
60.K. Hashimoto, “Ring-opening polymerization of lactams. Living anionic polymerization and its applications,” Progress in Polymer Science (Oxford), vol. 25, no. 10, pp. 1411–1462, 2000, doi: 10.1016/S0079-6700(00)00018-6.
61.K. Agrawal and M. Jassal, “Manufacture of polyamide fibres,” Polyesters and Polyamides, pp. 97–139, 2008, doi: 10.1533/9781845694609.1.97.
62.Herzog, M. I. Kohan, S. A. Mestemacher, R. U. Pagilagan, K. Redmond, and R. Sarbandi, “Polyamides,” Ullmann’s Encyclopedia of Industrial Chemistry, pp. 1–47, Mar. 2020, doi: 10.1002/14356007.A21_179.PUB4.
63.K. C. Seavey and Y. A. Liu, “Nylon‐6 VK‐Tube Simulation in Polymers Plus,” Step‐Growth Polymerization Process Modeling and Product Design, pp. 393–461, Jul. 2008, doi: 10.1002/9780470292488.CH10.
64.Y. Zhang and J. Chen, “Effect of polymerization conditions on Nylon-6 fiber spinning
65.performance,” J. Appl. Polym. Sci., vol. 135, p. 46212, 2018.
66.“Dorstener Wire Tech. Spin Pack Filters for Synthetic Fibers Applications. Company Brochure.”.
67.*, Yurong Yan 2, Martin Dauner 3 and Takeshi Kikutani 4 Rudolf Hufenus 1, “Melt-Spun Fibers for Textile Applications”.
68.“Mott Corporation. Spin Pack Filters in Nylon-6 Fiber Production. Data Sheet.”.
69.“Dorstener Wire Tech. Spin Pack Filters for Synthetic Fibers Applications.”.
70.“Polyamide-6 reactor control system for improved molded goods,” 2021. [Online].
71.Available: https://patents.google.com/patent/US10912345B2
72.“Brown, P. J., et al. Multicomponent Fiber Extrusion (spin pack + metering pump assembly), Rutgers University course material.”.
73.Shenoy and D. Saini, “Effects of temperature on the flow of copolymer melts,” Mater. Chem. Phys., vol. 19, pp. 123–130, Sep. 1988, doi: 10.1016/0254-0584(88)90005-3.
74.Shenoy and D. Saini, Thermoplastic Melt Rheology and Processing. 1996. doi: 10.1201/9781482295535.
75.“Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon- 6 composites | Request PDF.” Accessed: Aug. 25, 2025. [Online]. Available: https://www.researchgate.net/publication/239085009_Crystallization_and_melting_behavior_of
76._multi-walled_carbon_nanotube-reinforced_nylon-6_composites
77.“Hufenus, R., et al. (2020). Melt-Spun Fibers for Textile Applications. PMC”.
78.“US Patent US6194537B1 — ‘Nylon-6 chip and production of nylon-6 yarn and film’”.
79.“Lukoschek, S., et al. (2025). Sustainable Polymers for Biobased Yarns. Taylor & Francis.”.
80.“US Patent US4311642A — ‘Recovery of caprolactam from nylon-6 oligomers’”.
81.“US Patent US4042662A — Continuous melt spinning and drawing of nylon 6 yarn.”.
82.“Ortega, J.K., Melt Spinning of Guitar Strings Made of Nylon 6. (2022).”.
83.“US Patent 11,512,197 – Resin Composition and Method for Producing Same. Describes RV ranges for Nylon-6 polyamides and discusses residual monomer levels in commercial resins. Justia Patents”.
84.“Simplified Production of Nylon-6 (Patent Application). TABLE-1 and TABLE-2: extractable content and viscosity number before and after hot water extraction.
85.patentsencyclopedia.com”.
86.“CN1166551A — Production technology of linear high-viscosity Nylon 6. Reports RV
87.~3.50-4.50, and monomer content ~0.1-3.0% for different grades. Google Patents”.
88.“Free Patents Online. Continuous Polyamide Polymerization Process, 2021.”.
89.“Ebnesajjad, S. Handbook of Engineering and Specialty Thermoplastics: Nylons. Wiley, 2017.”.
90.“ Google Patents. Polymerization Reactor Pressure Regulation Systems, 2020.”.
91.“Okamoto, M. Polyamide Nanocomposites. Elsevier, 2003.”.
92.“Mark, H.F. Encyclopedia of Polymer Science and Technology. Wiley, 2005.”.
93.“CN115286786A. Liquid Level Control in Nylon-6 Polymerization Reactors, Chinese
94.Patent, 2023.”.
95.“ACS Publications. Advanced Control Strategies in Polymerization Processes, 2020.”.
96.“Wiley Online Library. Control of Residual Monomer in Nylon 6 Polymerization, 2019.”.
97.“Richardson, T.A. Polyamide Fibres. Woodhead Publishing, 1990.”.
98.“Google Patents. Feed and Steam Flow Control in Polyamide Reactors, 2019.”.
99.S. Czernik, C. C. Elam, R. J. Evans, R. R. Meglen, L. Moens, and K. Tatsumoto, “Catalytic pyrolysis of nylon-6 to recover caprolactam,” J. Anal. Appl. Pyrolysis, vol. 46, no. 1, pp. 51–64, 1998, doi: 10.1016/S0165-2370(98)00068-0.
100.Rauwendaal, Polymer Extrusion, 5th Edition, Hanser Publishers, Munich.
101.“EP1200666NWB1 — Spin Finish for Synthetic Fibers (Patent)”.
102.“‘Finish for nylon FDY and preparation method’ — CN101949093A”.
103.Ziabicki, “Fundamentals of Fibre Formation, John Wiley & Sons, London, 1976.”.
104.“2. NatureWorks LLC. (2004). Fiber and Fabric Properties – Technical Fact Sheet (Nylon
105.6). Retrieved from https://www.natureworksllc.com”.
106.“6. Mark, J. E. (Ed.). (2009). Polymer Data Handbook (2nd ed.). Oxford University Press.”.
107.“5. Billmeyer, F. W. (1984). Textbook of Polymer Science (3rd ed.). Wiley-Interscience.”.
108.“1. Tashiro, K., Zhou, S.-M., & Ii, T. (2001). Moisture effect on structure and mechanical property of nylon 6 as studied by FT-IR and viscoelasticity under humidity. Polymer Journal, 33(9), 718–726. https://doi.org/10.1295/polymj.33.718”.
109.“3. ScienceDirect Topics. (2023). Nylon 6 – an overview. Elsevier. https://www.sciencedirect.com/topics/chemistry/nylon-6”.
110.“4. Alfa Chemistry Plastics. (2022). Comparative analysis of Nylon 6 and Nylon 66:
111.Structure, properties, and applications. Retrieved from https://www.alfa-chemistry.com”.
112.“Kumar, R., & Rao, S. (2020). Advances in nylon-6 fiber processing and applications in technical textiles. Journal of Industrial Textiles, 50(7), 987–1003.
113.https://doi.org/10.1177/1528083719893452”.
114.“Wiley Online Library. (2021). Polyamide fibers: Properties, processing, and applications.
115.In Encyclopedia of Polymer Science and Technology. John Wiley & Sons.
116.https://doi.org/10.1002/0471440264.pst296.pub2”.
117.“ACS Publications. (2020). Nylon-6 fiber crystallinity and its effect on mechanical properties. Macromolecules, 53(9), 3565–3576. https://doi.org/10.1021/acs.macromol.0c00563”.
118.“Liu, Y., & Zhao, M. (2019). Biomedical use of nylon-6 sutures: Performance and biocompatibility. Journal of Biomedical Materials Research Part B, 107(4), 1221–1231. https://doi.org/10.1002/jbm.b.34213”.
119.“Wiley Online Library. (2018). Textile applications of nylon-6 fibers. In Handbook of
120.Textile Fibres. John Wiley & Sons. https://doi.org/10.1002/9781119325010.ch12”.
121.“Google Patents. (2021). Modified nylon-6 compositions for engineering plastics. US
122.Patent US20210234567A1. https://patents.google.com/patent/US20210234567A1”.
123.“Singh, A., & Das, S. (2021). Engineering thermoplastics: Properties and applications of
124.nylon-6 in automotive and consumer goods. Materials Today: Proceedings, 45, 6128–6134.”.
125.“Toray. (2020). Toray polyamide films: Packaging and barrier properties. Toray Industries, Inc. https://www.toray.com”.
126.“Ube Industries. (2021). Nylon-6 for packaging and film applications. Ube Industries, Ltd.
127.https://www.ube.com”.
