Structural and Dielectric Properties of Pristine Bentonite-PVC Nanocomposites

Abstract

In this study, the structural and dielectric properties of pristine bentonite-PVC (Polyvinyl chloride) nanocomposites were systematically investigated. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses confirmed the partial intercalation of PVC molecules between the bentonite layers and their interaction with surface hydroxyl groups. The dielectric properties of the nanocomposites were examined via impedance spectroscopy over a broad frequency range of 1 Hz–10 MHz. The results revealed that PVC loading significantly influenced dielectric permittivity, dielectric loss, and loss tangent (tan δ). At low frequencies (<1 kHz), the permittivity and dielectric loss values of 25 mg, 35 mg, and 100 mg PVC-loaded nanocomposites were notably higher compared to pristine bentonite, indicating enhanced interfacial polarization. The relaxation frequency of pristine bentonite was determined to be 39 kHz, which shifted to lower frequencies upon polymer loading due to intercalation and surface interactions. Notably, in the 35 mg PVC-loaded nanocomposite, the relaxation frequency decreased to 12 kHz, suggesting stronger polymer-clay interactions. In addition, AC conductivity (σac) analyses were performed and successfully fitted with the Jonscher power law, confirming the dominant role of interfacial polarization and dipolar confinement on charge transport behavior. These findings demonstrate that the dielectric behavior of PVC-bentonite nanocomposites is governed by both intercalation and surface interactions, which modulate charge carrier mobility and polarization mechanisms. The integration of structural (XRD, FTIR) and dielectric (impedance spectroscopy) analyses provides a comprehensive understanding of the impact of polymer loading on the dielectric performance of bentonite-based nanocomposites.

Keywords

• Bentonite/PVC nanocomposites
• Dielectric properties
• Intercalation and surface interactions
• Electrode polarization
• Structural analyses

References

1. [1] Alexandre, M., and Dubois, P., “Polymer-layered silicate nanocomposites: preparation, properties and uses of a new class of materials”, Materials Science and Engineering, 28: 1-63, (2000). DOI: https://doi.org/10.1016/S0927-796X(00)00012-7
2. [2] Ray, S.S., and Okamoto, M., “Polymer/layered silicate nanocomposites: a review from preparation to processing”, Progress in Polymer Science, 28: 1539–1641, (2003). DOI: https://doi.org/10.1016/j.progpolymsci.2003.08.002
3. [3] Sheng, N., “Multiscale Micromechanical Modeling of the Thermal/Mechanical Properties of Polymer/Clay Nanocomposites”, Phd. Thesis, Massachusetts Institute of Technology, Massachusetts, 1-183, (2006)
4. [4] Wang, L., Wang, K., Chen, L., and Zhang, Y., “Preparation, morphology and thermal/mechanical properties of epoxy/nanoclay composite”, Composites: Part A, 37: 1890–1896, (2006). DOI: https://doi.org/10.1016/j.compositesa.2005.12.020
5. [5] Bhatt, C., Swaroop, R., Arya, A., and Sharma, A.L., “Effect of nano-filler on the properties of polymer nanocomposite films of PEO/PAN complexed with NaPF6”, Journal of Materials Science and Engineering B, 5: 11-12, (2015). DOI: https://doi.org/10.17265/2161-6221/2015.11-12.003
6. [6] Kaya, A.U., Guner, S., and Esmer, K., “Effects of solution mixing temperature on dielectric properties of PMMA/pristine bentonite nanocomposites”, Journal of Applied Polymer Science, 131: 39907-39914, (2014). DOI: https://doi.org/10.1002/app.39907
7. [7] Mansur, H.S., Sadahira, C.M., Souza, A.N., and Mansur, A.P., “FTIR spectroscopy characterization of poly(vinyl alcohol) hydrogel with different hydrolysis degree and chemically crosslinked with glutaraldehyde”, Materials Science and Engineering C, 28: 539–548, (2008). DOI: https://doi.org/10.1016/j.msec.2007.10.088
8. [8] Mohamed, A.T., “Thermal experimental verification on effects of nanoparticles for enhancing electric and dielectric performance of polyvinyl chloride”, Measurement, 89: 28–33, (2016). DOI: https://doi.org/10.1016/j.measurement.2016.04.002

9. [9] Rozik, N.N., Abd-El Messieh, L.L., and Abd-El Nour, K.N., “The effect of modified pluronic on the distribution of fillers in the polyvinyl chloride matrix”, Journal of Applied Polymer Science, 115: 1732–1741, (2010). DOI: https://doi.org/10.1002/app.31217
10. [10] Silva, T.F., Soares, B.G., Ferreire, S.C., and Sebastian, L., “Silylated montmorillonite as nanofillers for plasticized PVC nanocomposites: Effect of the plasticizer”, Applied Clay Science, 99: 93–99, (2014). DOI: https://doi.org/10.1016/j.clay.2014.06.017
11. [11] Gouda, O.E., Darwish, M.M.F., Thabet, A., Lehtonen, M., and Osman, G.F.A., “Enhancement of the underground cable current capacity by using nano-dielectrics”, Energy Science and Engineering, 12: 3647–3662, (2024). DOI: https://doi.org/10.1002/ese3.1822
12. [12] Akar, Y., and Kaya, A.U., “Investigation of structural, thermal and dielectric properties of PVA/Na-Bentonite composites”, Journal of the Faculty of Engineering and Architecture of Gazi University, 40: 287-295, (2025). DOI: https://doi.org/10.17341/gazimmfd.1401676
13. [13] Wilson, M.J., Clay Mineralogy: Spectroscopic and Chemical Determinative Methods, 1st ed., Springer, Dordrecht, (1994).
14. [14] Madejova, J., “FTIR techniques in clay mineral studies”, Vibrational Spectroscopy, 31: 1–10, (2003). DOI: https://doi.org/10.1016/S0924-2031(02)00065-6
15. [15] Kumari, N., Mohan, C., and Negi, A., “An investigative study on the structural, thermal and mechanical properties of clay-based PVC polymer composite films”, Polymers, 15: 1922-1937, (2023). DOI: https://doi.org/10.3390/polym15081922
16. [16] Erdem, M., Ortac, K., Erdem, B., and Turk, H., “Reaktif organobentonit katkilarin sert poliuretan kopugun bazi performans ozellikleri uzerine etkisi”, Journal of the Faculty of Engineering and Architecture of Gazi University, 32: 1209-1219, (2017). DOI: https://doi.org/10.17341/gazimmfd.369543
17. [17] Shanmugharaj, A.M., Rhee, K.Y., and Ryu, S.H., “Influence of dispersing medium on grafting of aminopropyltriethoxysilane in swelling clay materials”, Journal of Colloid and Interface Science, 298: 854–859, (2006). DOI: https://doi.org/10.1016/j.jcis.2005.12.049
18. [18] Chuajiw, W., Nakano, M., Takatori, K., Kojima, T., Wakimoto, Y., and Fukushima, Y., “Effects of amine, amine salt and amide on the behaviour of carbon dioxide absorption into calcium hydroxide suspension to precipitate calcium carbonate”, Journal of Environmental Sciences, 25: 2507–2515, (2013). DOI: https://doi.org/10.1016/S1001-0742(12)60284-8
19. [19] Branca, C., D’Angelo, G., Crupi, C., Khouzami, K., Rifici, S., Ruello, G., and Wanderlingh, U., “Role of the OH and NH vibrational groups in polysaccharide nanocomposite interactions: A FTIR-ATR study on chitosan and chitosan/clay films”, Polymer, 99: 614-622, (2016). DOI: https://doi.org/10.1016/j.polymer.2016.07.086
20. [20] Czako, E., Vymazal, Z., Volka, K., Stibor, I., and Stepek, J., “Effect of stabilizers in the thermal treatment of PVC-VI. An I.R. spectroscopic study of the stabilization of PVC with Ba and Cd stearates”, European Polymer Journal, 15: 81-85, (1979). DOI: https://doi.org/10.1016/0014-3057(79)90253-2
21. [21] Efimov, A.M., and Pogareva, V.G., “IR absorption spectra of vitreous silica and silicate glasses: The nature of bands in the 1300 to 5000 cm-1 region”, Chemical Geology, 229: 198–217, (2006). DOI: https://doi.org/10.1016/j.chemgeo.2006.01.022
22. [22] Kotal, M., and Bhowmick, A.K., “Polymer nanocomposites from modified clays: Recent advances and challenges”, Progress in Polymer Science, 51: 127–187, (2015). DOI: https://doi.org/10.1016/j.progpolymsci.2015.10.001
23. [23] Gong, F., Feng, F., Zhao, C., Zhang, S., and Yang, M., “Thermal properties of poly(vinyl chloride)/montmorillonite nanocomposites”, Polymer Degradation and Stability 84: (2004) 289-294 (2004). DOI: https://doi.org/10.1016/j.polymdegradstab.2003.11.003
24. [24] Zhu, R., Zhu, J., Ge, F., and Yuan, P., “Regeneration of spent organoclays after the sorption of organic pollutants: A review”, Journal of Environmental Management, 90: 3212–3216, (2009). DOI: https://doi.org/10.1016/j.jenvman.2009.06.015
25. [25] Li, M., Wu, Z., and Ge, F., “A review of intercalation composite phase change material: Preparation, structure and properties”, Renewable and Sustainable Energy Reviews, 16: 2094-2101, (2012). DOI: https://doi.org/10.1016/j.rser.2012.01.016
26. [26] Tournassat, C., Bizi, M., Braibant, G., and Crouzet, C., “Influence of montmorillonite tactoid size on Na-Ca cation exchange reactions”, Journal of Colloid and Interface Science, 15: 443–454, (2011). DOI: https://doi.org/10.1016/j.jcis.2011.07.039
27. [27] Elashmawi, I.S., Elsayed, N.H., and Altalhi, F.A., “The changes of spectroscopic, thermal and electrical properties of PVDF/PEO containing lithium nanoparticles”, Journal of Alloys and Compounds, 617: 877–883, (2014). DOI: https://doi.org/10.1016/j.jallcom.2014.08.088
28. [28] Chen, R.S., Ahmad, S., and Gan, S., “Characterization of recycled thermoplastics-based nanocomposites: Polymer-clay compatibility, blending procedure, processing condition, and clay content effects”, Composites Part B: Engineering, 131: 87-97, (2017). DOI: https://doi.org/10.1016/j.compositesb.2017.07.057
29. [29] Fal, J., Bulanda, K., Oleksy, M., and Zyla, G., “Effect of bentonite on the electrical properties of a polylactide-based nanocomposite”, Polymers, 16(10): 1372, (2024). DOI: https://doi.org/10.3390/polym16101372
30. [30] El-Khalafy, S.H., Hassanein, M.T., Alaskary, M.M., Ramzy, G.H., and Ali, A.I., “Synthesis, characterization, and dielectric properties of bentonite clay modified with (3-chloropropyl) triethoxysilane and Co(II) porphyrin complex for technological and electronic device applications”, Materials Advances, 6: 1931–1949, (2025). DOI: https: //doi.org/ 10.1039/d4ma00982g