The effect of nanoclay on the creation of clusters of polyamide 6 microfibrils

Document Type : Research Article


1 Polymer and Textile Department, Islamic Azad University, South Tehran Branch, Tehran, Iran

2 Iran Polymer and Petrochemical Institute (IPPI), Tehran, Iran


The PA6/clay nanocomposites were prepared during in-situ anionic ring-opening polymerization (AROP) via reactive melt blending in a Hakke internal mixer. Then, the samples were characterized using FT-IR, DSC, DMTA, rheometer, XRD, SEM/EDX/elemental mapping, TEM, and HT-GPC to study the effects of Cloisite 15A on PA6 properties. The results showed that nanoclay caused a decrease in the ultimate tensile strength (UTS), crystallinity, Tm, Tg, and tan δ of the samples. However, it increased the Young′s modulus and stress rupture of the samples. Furthermore, the nanocomposites showed a pseudo-solid behavior because of the reinforcing effect of the nanoparticles. Additionally, α crystals were not seen in the samples with 1 and 3 % nanoclay; however, γ crystals were observable in those samples. Also, nanoclay decreased PA6 viscosity and increased dispersity and residual monomers in the nanocomposite samples. The nanoclays exfoliated in the sample have 0.5 % nanoparticles, but they were intercalated by more loading in the PA6 matrix. Moreover, the PA6 microfibrils were observed as sporadic and clay-centered clusters in the SEM micrographs of the pure and nanocomposite samples, respectively. Therefore, the clustering of PA6 microfibrils in the matrix during in-situ AROP is considered a novelty in current research.

Graphical Abstract

The effect of nanoclay on the creation of clusters of polyamide 6 microfibrils


  • In the PA6/clay nanocomposite (0.5 % nanoclay), the nanoparticles were exfoliated.
  • In the PA6/clay nanocomposites (1 and 3% nanoclay), the particles were intercalated.
  • The PA6/clay nanocomposite showed a pseudo-solid behavior.
  • The clay-centered PA6 microfibrils clustering during AROP has not been reported before.
  • The clusters of PA6 microfibrils formed whose growth from the nanoclay.


Main Subjects

[1] Pramoda, K., and Liu, T. (2004).  Effect of moisture on the dynamic mechanical relaxation of polyamide‐6/clay nanocomposites. J. Polym. Sci. Pol. Phys. 42(10)1823-1830. 
[2] Xu, M., Chen, Y., Liu, T., Zhao, L., & Park, C.B. (2019). Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements. J. Appl. Polym. Sci. 136(42) 48138.
[3] Guo, F., Aryana, S., Han, Y., & Jiao, Y. (2018). A review of the synthesis and applications of polymer-nanoclay composites. Appl. Sci. 8(9) 1696. 
[4] Khaimov, V., Kohse, S., Arbeiter, D., Grabow, N., Schmitz, K.P. (2018). Nanofibrous polyamide 6 scaffolds promote adhesion of endothelial cells. Biomed. Eng. 4(1) 637-640. 
[5] Hammami, I., Hammami, H., Soulestin, J., Arous, M., & Kallel, A. (2019). Thermal and dielectric behavior of polyamide-6/clay nanocomposites. Mater. Chem. Phys. 232, 99-108.  
[6] Ghanta, T.S., Aparna, S., Verma, N., & Purnima, D. (2020). Review on nano- and microfilter-based polyamide 6 hybrid composite: Effect on mechanical properties and morphology. Polym. Eng. Sci. 60(8) 1717-1759. 
[7] Gupta, B., Lacrampe, M.F., & Krawczak P. (2006). Polyamide-6/clay nanocomposites: A critical review. Polym. Polym. Comp. 14(1) 13-3.
[8] Alonso-Montemayor, F.J., Tarrés, Q., Oliver-Ortega, H., Espinach, F.X., Idalia Narro-Céspedes, R., Castañeda-Facio, A.O., & Delgado-Aguilar, M. (2020). Enhancing the mechanical performance of bleached hemp fibers reinforced polyamide 6 composites: A competitive alternative to commodity composites. Polymers-Basel, 12(5) 1041.
[9] Holec, P., Jirkovec, R., Kalous, T., Baťka, O., Brožek, J., & Chvojka, J. (2022). The potential for the direct and alternating current-driven electrospinning of polyamides. Nanomaterials-Basel, 12(4), 665. 
[10] Xu, M., Lu, J., Qiao, Y., Wei, L., Liua, T., Lee, P.C., Zhao, L., & Park, C.B. (2020). Toughening mechanism of long-chain branched polyamide 6. Mater. Design, 196, 109173.
[11] Xu, M., Lu, J., Zhao, J., Wei, L., Liu, T., Zhao, L., & Park, C.B. (2021). Rheological and foaming behaviors of long-chain branched polyamide 6 with controlled branch length. Polymer, 224, 123730.
[12] Zhang X., and Loo, L.S. (2008). Morphology and mechanical properties of a novel amorphous polyamide/nanoclay nanocomposite. J. Polym. Sci. Pol. Phys. 46(23) 2605-2617.
[13] Baniasadi, H., Trifol, J., Ranta, A., & Seppala, J. (2021). Exfoliated clay nanocomposites of renewable long-chain aliphatic polyamide through in-situ polymerization. Compos. Part B-Eng. 211, 108655. 
[14] Mahmud, M.B., Anstey, A., Shaayegan, V., Lee, P.C., & Park, C.B. (2020). Enhancing the mechanical performance of PA6 based composites by altering their crystallization and rheological behavior via in-situ generated PPS nanofibrils. Compos. Part B-Eng. 195, 108067.
[15] Krasinskyi, V., Suberlyak, O., Sikor, J., & Zemke, V. (2021). Nanocomposites based on polyamide-6 and montmorillonite intercalated with polyvinylpyrrolidone. Polym. Plast. Technol. Mater. 60(15) 1641-1655.
[16] Sakai, T., Shamsudim, N.S., Fukushima, R., & Kageyama, K. (2021) Effect of matrix crystallinity of carbon fiber reinforced polyamide 6 on static bending properties. Adv. Compos. Mater. 30(2) 71-84.
[17] Chen, Y., Waghmare, P.R., & Ayranci, C. (2019). Fabrication and characterization of electrospun mats of nylon 6/silica nanocomposite fibers. J. Eng. Fiber. Fabr. 14, doi:10.1177/1558925019843225.
[18] Choi, J., Shin, T., Song, K., Seo, Y. P., & Seo, Y. (2020). Nonisothermal crystallization behaviors of structure-modified polyamides (Nylon 6s). ACS Omega, 5(45) 29325-29332.
[19] Zhang T. and Kang, H.J. (2021). Enhancement of the processability and properties of nylon 6 by blending with polyketone. Polymers-Basel, 13(19) 3403.
[20] Cai, L., Lin, Z., & Qian, H. (2010). Dispersion of nano-silica in monomer casting nylon6 and its effect on the structure and properties of composites. Express Polym. Lett. 4(7) 397-403. 
[21] Nuyken O. and Pask, S.D. (2013). Ring-opening polymerization - An introductory review. Polymers-Basel, 5(2) 361-403.
[22] Peter, C., LeBaron, P.C., Wang, Z., & Pinnavaia, T.J. (1999). Polymer-layered silicate nanocomposites: An overview. Appl. Clay Sci. 15(1-2) 11-29.
[23] Fornes, T. and Paul, D.R. (2003). Crystallization behavior of nylon 6 nanocomposites. Polymer, 44(14) 3945-3961. 
[24] Ding, W., Zhou, Y., Wang, W., & Wang, J. (2020) The reactive compatibilization of montmorillonite for immiscible anionic polyamide 6/polystyrene blends via in-situ polymerization. Polym.-Plast. Technol. Mater. 59(8) 1-11.
[25] Kausar, A. (2022). Polyamide/nanosilica nano-composite: A chronicle of design and high-tech progressions. Mater. Res. Innov. 26(22) 52-63.
[26] Khanyile, N. (2022). Advances in nanostructured polyamide-based chemical sensors. J. Nanomater. 2022, 5543283. 
[27] Münstedt, H. (2021). Rheological measurements and structural analysis of polymeric materials. Polymers-Basel, 13(7) 1123.
[28] Morimune-Moriya, S., Yada, S. I., Kuroki, N., Ito, S., Hashimoto, T., & Nishino, T. (2020). Strong reinforcement effects of nanodiamond on mechanical and thermal properties of polyamide 66. Comp. Sci. Technol. 199, 108356.
[29] Fabia, J., Gawłowski, A., Rom, M., Slusarczyk, C., Brzozowska-Stanuch, A., & Sieradzka, M. (2020). PET Fibers modified with cloisite nanoclay. Polymers-Basel, 12(4) 774.
[30] Shanmugan, S., Gorjian, S., Elsheikh, A.H., Essa, F.A., Omara, Z.M., & Raghu, A.V. (2021). Investigation into the efects of SiO2/TiO2 nanolayer on the thermal performance of solar box type cooker. Energ. Source. Part A, 43(21) 2724-2737.
[31] Lincoln, D.M., Vaia, R.A., Wang, Z.G., & Hsiao, B.S. (2001). Secondary structure and elevated temperature crystallite morphology of nylon-6/layered silicate nanocomposites. Polymer, 42(4) 1621-1631.
[32] El-Gabry, L.K., Nasr, M.F., & Abou El-Kheir, A.A. 1 (2020). A new economical technique for dyeing polyamide fiber/nanoclay composite with basic dye. Res. J. Text. Appar. 25(1) 47-63.
[33] Yang, M., Gao, Y., & Li, H.M. (2007). Preparation of polyamide 6/silica nanocomposites from silica surface initiated ring-opening anionic polymerization. Express Polym. Lett. 1(7) 433-442.
[34] Chen, J., Beake, B.D., Bell, G.A., Tait Y., & Gao, F. (2016). Investigation of the nanomechanical properties of nylon 6 and nylon 6/clay nanocomposites at sub-ambient temperatures. J. Exp. Nanosci. 11(9) 695-706. 
[35] Li, Y., Liu, K., & Xiao, R. (2017). Preparation and characterization of flame-retarded polyamide 66 with melamine cyanurate by in-situ polymerization. Macromol. Res. 25(8) 779-785. 
[36] Wu, H., Krifa, M., & Koo, J.H. (2014). Flame retardant polyamide 6/nanoclay/ intumescent nanocomposite fibers through electrospinning. Text. Res. J. 84(10) 1-13.
[37] Abdel Alim Sadik, W., Maghraby El Demerdash, A.G., Abbas, R., & Bedir, A. (2020). Impact of hybrid nanosilica and nanoclay on the properties of palm rachis-reinforced recycled linear low-density polyethylene composites. J. Thermoplast. Compos. 35(11) 2032-2051.
[38] Nagy D., & Kókai, E. (2018). Polymer-based nanocomposites with nanoclay. IOP Conf. Ser.-Mat. Sci. 448, 012021. 
[39] Li, Q., Gao, D., Wei, Q., Ge, M., Liu, W., Wang, L., & Hu, K. (2010). Thermal stability and crystalline of electrospun polyamide 6/organo-montmorillonite nanofibers. J. Appl. Polym. Sci. 117(3) 1572-1577.
[40] Kanapitsas, A., Pissis, P., & Kotsilkov, R. (2002). Dielectric studies of molecular mobility and phase morphology in polymer–layered silicate nanocomposites. J. Non-Cryst. Solids, 305, 204-211.
[41] Koo, C.M., Kim, S.O., & Chung, I.J. (2003). Study on morphology evolution, orientational behavior, and anisotropic phase formation of highly filled polymer-layered silicate nanocomposites. Macromolecules, 36(8) 2748-2757.
[42] Hanemann, T., & Szabó, D.V. (2010). Polymer-nanoparticle composites: from synthesis to modern applications. Materials, 3(6) 3468-3517.
[43] Abdelwahab, M., Codou, A., Anstey, A., Mohanty, A.K., & Misra, M. (2020). Studies on the dimensional stability and mechanical properties of nanobiocomposites from polyamide 6-filled with biocarbon and nanoclay hybrid systems. Compos. Part A- Appl. Sci. 129, 105695.
[44] Siddique, S., Leung, P.S., & Njuguna, J. (2021). Drilling oil-based mud waste as a resource for raw materials: A case study on clays reclamation and their application as fillers in polyamide 6 composites. Upstream Oil Gas Technol. 7, 100036.
[45] Gill, Y.Q., Abid, U., & Song, M. (2020). High performance nylon12/clay nanocomposites for potential packaging applications. J. Appl. Polym. Sci. 137(41) 49247.
[46] Mekhzoum, M.E.M., Raji, M., Rodrigue, D., El Kacem Qaissa, A., & Bouhfid, R. (2020). The effect of benzothiazolium surfactant modified montmorillonite content on the properties of polyamide 6 nanocomposites. Appl. Clay Sci. 185, 105417.
[47] Tuna, B., & Benkreira, H. (2019). Chain extension of polyamide 6/organoclay nanocomposites. Polym. Eng. Sci. 59(6) 1233-1241.
[48] Krishnamoorti, R., & Yurekli, K. (2001). Rheology of polymer layered silicate nanocomposites. Curr. Opin. Colloid In. 6(5-6) 464-470.
[49] Kakuta, T., Baba, Y., Yamagishi, T.A., & Ogoshi, T. (2021). Supramolecular exfoliation of layer silicate clay by novel cationic Pillar[5]arene intercalants. Sci. Rep.-UK, 11, 10637.
[50] Saha, M., Ray, R., Choudhury, A.R., De Bhowmik, P., & Kumar Ballabh, T. (2021). Impact of exfoliation/intercalation of nano-clay on structure, morphology and electrical properties of poly(ethylene oxide) based solid nanocomposite electrolytes. J. Polym. Res. 28(8) 299.
[51] Ruymbeke, E.V., Slot, J.J.M., Kapnistos, M., & PAM, S. (2013) Structure and rheology of branched polyamide 6 polymers from their reaction recipe. Soft Matter, 9(29) 6921-6935. 
[52] Anisio da Paz, R., Melissa, A., Leite, D., Maria Araújo, E., da Medeiros, V.N., Jeferson de Melo, T.A., & Pessan, L.A. (2016). Mechanical and thermomechanical properties of polyamide 6/brazilian organoclay nanocomposites. Polímeros, 26(1) 52-60.
[53] Ehsan, K. Y. A., Avramenko, V., & Ahmadi, S. (2013). Reducing the flammability of nylon-6 by introducing a fireproofing agent during the anionic polymerization of ε-caprolactam. Int. Polym. Sci. Technol. 40(9) 19-21. 
[54] Li, L., & Yang, G. (2009). Synthesis and properties of hydroxyapatite nanorod-reinforced polyamide 6 nanocomposites. Polym. Int. 58(4) 380-387. 
[55] Xu, Q., Chen, F., Li, X., & Zhang, Z. (2013). The effect of surface functional groups of nanosilica on the properties of polyamide 6/SiO2 nanocomposite. Poli. J. Chem. Technol. 15(3) 20-24.
[56] Sar, P., Ghosh Roy, S., De, P., & Ghosh S. (2020). Synthesis of glutamic acid derived organogels and their applications in dye removal from aqueous medium. Macromol. Mater. Eng. 305(4) 1900809.
[57] Zanoag, M., Airinei, A., Fifere, N., Grigoras, C.V., Ţîmpu, D., & Tanasa, F. (2021). Critical assessment of structural changes in some co-polyamide-clay hybrid materials in correlation with the filler characteristics. Polym. Compos. 42(11) 5936-5951.
[58] Zhang, S., Zhang, J., Tang, L., Huang, J., Fang, Y., Ji, P., Wang, C., & Wang, H. (2019). A novel synthetic strategy for preparing polyamide 6 (PA6)-based polymer with transesterification. Polymers-Basel, 11(6) 978.
[59] Vasanthan, N., & Salem, D. (2001). FTIR Spectroscopic characterization of structural changes in polyamide 6 fibers during annealing and drawing. J. Polym. Sci. Pol. Phys. 39(5) 536-547.
[60] Geethamma, V. G., Asaletha, R., Kalarikkal, N., & Thomas, S. (2014). Vibration and sound damping in polymers. Resonance, 19, 821-833. 
[61] Kiziltas, E., Yang, H. S., & Kiziltas, A., Boran, S., Douglas, E., & Gardner, J. (2016). Thermal analysis of polyamide 6 composites filled by natural fiber blend. Bioresources, 11(2) 4758-4769. 
[62] Hutchinson, J. M. (2009). Determination of the glass transition temperature. Methods correlation and structural heterogeneity. J. Therm. Anal. Calorim. 98, 579-589.
[63] Reyhani, R., Zadhoush,  A., Salman Tabrizi, N., Nazockdast, H., & Naeimirad, M.R. (2021). The influence of CNT-doped carbon aerogels on microstructural, rheological and mechanical properties of epoxy nanocomposites. Compos. Sci. Technol. 215, 109031. 
[64] Taghizadeh, E., Naderi, G., & Dubois, C. (2010). Rheological and morphological properties of PA6/ECO nanocomposites. Rheol. Acta 49, 1015-1027. 
[65] Han, Y.K., Um, J.W., Im, S.S., &  Kim, B.C. (2001) Synthesis and characterization of high molecular weight branched PBA. J. Polym. Sci. Pol. Chem. 39(13) 2143-2150.
[66] Gad, M.M., Rahoma, A., & Al-Thobity, A.M. (2018). Effect of polymerization technique and glass fiber addition on the surface roughness and hardness of PMMA denture base material. Dent. Mater. J. 37(5) 746-753.