The Tensile Properties and Microstructural Characteristics of Pulverised Silica-Coated Kenaf–Epoxy Composites
M.J. MEELAD, N.Z. NORIMAN, M.A. AZIZAN, M.F. OMAR, A.Z. ROMLI, R. HAMZAH, N. ISHAK, S.T. SAM
Abstract: Natural-fibre reinforced polymer composites offer sustainable alternatives for lightweight structural applications, yet their mechanical performance is often limited by insufficient interfacial adhesion, poor resin wet-out, and microstructural defects. This study investigates the tensile behaviour and microstructural characteristics of pulverised silica-coated kenaf–epoxy composites with varying nanosilica content (1 %, 2 %, 3 %) and kenaf loadings (5–25 wt%). Kenaf fibres were surface-treated with an epoxy–acetone–nanosilica mixture to enhance interphase formation and subsequently pulverised to produce hybrid fiber-particulate reinforcements. Composites were fabricated via hand lay-up followed by compression molding, and tensile properties were evaluated according to ASTM D638. Fractured specimens were analyzed using optical microscopy to quantify void formation, debonding, fiber pull-out, and nanoparticle clustering. Results reveal a pronounced “optimum-then-penalty” behaviour: moderate nanosilica loadings (2 wt%) and intermediate kenaf content (15 wt%) yielded the highest tensile modulus, strength, and strain due to improved fiber–matrix bonding and efficient stress transfer. Excessive nanosilica or fiber content reduced mechanical performance through particle agglomeration, resin starvation, and increased porosity. Optical microscopy confirmed that low void fractions, short debond channels, and tortuous crack paths correlate with enhanced tensile response, whereas abundant voids and clustering at high filler fractions initiate premature failure. These findings demonstrate that careful control of both nanosilica and fiber content can optimize interphase quality, minimize microstructural defects, and maximize reinforcement efficiency. The combined mechanical and microstructural analysis provides a robust framework for designing high-performance, biomass-based epoxy composites with tailored tensile properties.
Keywords
Kenaf Fibre, Epoxy Composite, Nanosilica Surface Modification, Tensile Properties, Optical Microscopy, Fiber-Matrix Interphase
Published online 7/15/2026, 8 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: M.J. MEELAD, N.Z. NORIMAN, M.A. AZIZAN, M.F. OMAR, A.Z. ROMLI, R. HAMZAH, N. ISHAK, S.T. SAM, The Tensile Properties and Microstructural Characteristics of Pulverised Silica-Coated Kenaf–Epoxy Composites, Materials Research Proceedings, Vol. 68, pp 272-279, 2026
DOI: https://doi.org/10.21741/9781644904237-36
The article was published as article 36 of the book Green Materials, Processing & Characterization
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
References
[1] Munimathan, A., Muthu, K., Subramani, S., & Rajendran, S. (2024). Environmental behaviour of synthetic and natural fibre reinforced composites: A review. Advances in Mechanical Engineering. https://doi.org/10.1177/16878132241286020
[2] Sapiai, N., Salleh, M. S., Mustapha, F., & Yusof, N. M. (2020). Tensile and flexural properties of silica nanoparticles in fibre-reinforced polymer composites. Polymers, 12(11), 2733. https://doi.org/10.3390/polym12112733
[3] Atmakuri, A., Fong, A., Wong, D. H., Lau, S., Debnath, S., Anwar, M., Davies, I. J., & Johar, M. B. (2025). A review on the hybrid polymer composites comprising natural fibre and nanomaterial reinforcement. Journal of Composite Materials. Advance online publication. https://doi.org/10.1177/00219983251334861
[4] Uniyal, P., Gaur, P., Yadav, J., Bhalla, N. A., Khan, T., Junaedi, H., & Sebaey, T. A. (2025). A comprehensive review on the role of nanosilica as a toughening agent for enhanced epoxy composites for aerospace applications. ACS Omega, 10(15), 15810–15839
[5] Ram Subbiah, R., Arivumangai, A., Yuvaraj, G., Kaliappan, S., Balaji, V., & Patil, P. P. (2022). Effect of nanosilica on mechanical, thermal, fatigue, and antimicrobial properties of cardanol oil/sisal fiber reinforced epoxy composite. Polymer Composites, 43(12), 7364–7377. https://doi.org/10.1002/pc.26930
[6] Yogin Soodesh, C., & Roy, B. (2023). Natural fiber and nanoparticles reinforced natural fiber for structural composite applications. In Fiber Reinforced Polymeric Materials and Sustainable Structures (pp. 139–158). Springer. https://doi.org/10.1007/978-981-19-8979-7_11
[7] Jose, S., Thomas, S., & George, G. (2023). Nanosilica-incorporated coarse wool-epoxy hybrid composites: Mechanical, water-absorption and biodegradation behaviour. Frontiers in Materials, 10, 1140602. https://doi.org/10.3389/fmats.2023.1140602
[8] Rahman, M. R., et al. (2023). Design of hybrid kenaf/nanosilica epoxy composites: Experimental and computational approach. Materials Today Communications, 36, 105537. https://doi.org/10.1016/j.mtcomm.2023.105537
[9] Patel, B., & Das, A. (2024). Bio-based hybrid nanocomposites: Recent developments in mechanical optimization. Journal of Composite Materials, 58(3), 405–418. https://doi.org/10.1177/00219983231217392
[10] Nasir, M., et al. (2022). Epoxy/silica/kenaf hybrid composites: Fabrication and performance under mechanical loads. Polymers for Advanced Technologies, 33(6), 1899–1910. https://doi.org/10.1002/pat.5563
[11] Khoshnoud, A., et al. (2023). Optimization of nanosilica loading in bio-based epoxy composites. Construction and Building Materials, 371, 130708. https://doi.org/10.1016/j.conbuildmat.2023.130708
[12] Chin, C. W., et al. (2023). Microstructural behavior and tensile characteristics of epoxy-based kenaf-silica composites. Journal of Applied Polymer Science, 140(8), 53645. https://doi.org/10.1002/app.53645
[13] Rashid, Z., et al. (2023). Tensile and impact analysis of hybrid kenaf/nano-silica epoxy composites. Journal of Reinforced Plastics and Composites, 42(6), 421–431. https://doi.org/10.1177/07316844231123462
[14] Tan, Y. L., et al. (2022). Micromechanical fracture behavior of natural fiber/silica hybrid epoxy composites. Materials Today: Proceedings, 61(2), 152–159. https://doi.org/10.1016/j.matpr.2022.06.044
[15] Hasan, M. S., et al. (2024). Fractography and microstructure–property correlation of nanofilled kenaf–epoxy composites. Polymers and Polymer Composites, 32(1), 118–129. https://doi.org/10.1177/09673911231218312
[16] Jin, R., Xu, B., Guo, D., Shi, B., Chen, Y., Jia, X., & Qu, L. (2024). Advanced chemical modification technology of inorganic oxide nanoparticles in epoxy resin and mechanical properties of epoxy resin nanocomposites: A review. Nano Materials Science. https://doi.org/10.1016/j.nanoms.2024.10.006
[17] Kamarudin, S. H., Mohd Basri, M. S., Rayung, M., Abu, F., Ahmad, S., Norizan, M. N., Osman, S., Sarifuddin, N., Mat Desa, M. S. Z., Abdullah, U. H., Mohamed Amin Tawakkal, I. S., & Abdullah, L. C. (2022). A review on natural fibre reinforced polymer composites (NFRPC) for sustainable industrial applications. Polymers, 14(17), 3698. https://doi.org/10.3390/polym14173698
[18] Zappalorto, M., Pontefisso, A., Fabrizi, A., & Quaresimin, M. (2015). Mechanical behaviour of epoxy/silica nanocomposites: Experiments and modelling. Composites Part A: Applied Science and Manufacturing, 72, 58–64. https://doi.org/10.1016/j.compositesa.2015.01.027
[19] Madueke, C. I., Mbah, O. M., & Umunakwe, R. (2023). A review on the limitations of natural fibres and natural fibre composites with emphasis on tensile strength using coir as a case study. Polymer Bulletin, 80(4), 3489–3506. https://doi.org/10.1007/s00289-022-04241-y
[20] Sprenger, S. (2020). Nanosilica-toughened epoxy resins: mechanisms and performance. Polymers, 12(8), 1777. https://doi.org/10.3390/polym12081777
[21] Sapiai, N., Jumahat, A., Jawaid, M., Midani, M., & Khan, A. (2020). Tensile and flexural properties of silica-nanoparticles-modified unidirectional kenaf and hybrid glass/kenaf epoxy composites. Polymers, 12(11), 2733. https://doi.org/10.3390/polym12112733
[22] Li, Y., Li, Q., & Ma, H. (2015). The voids formation mechanisms and their effects on the mechanical properties of flax fiber reinforced epoxy composites. Composites Part A: Applied Science and Manufacturing, 72, 40‑48. https://doi.org/10.1016/j.compositesa.2015.01.029
[23] Ismail, A. S., Jawaid, M., & Naveen, J. (2019). Void content, tensile, vibration and acoustic properties of kenaf/bamboo fiber reinforced epoxy hybrid composites. Materials, 12(13), 2094. https://doi.org/10.3390/ma12132094
