Issue 78

R. Shivashankar et alii, Fracture and Structural Integrity, 78 (2026) 454-473; DOI: 10.3221/IGF-ESIS.78.26

Recent studies further demonstrate the potential of ceramic nanofillers in hybrid fiber composites. Improved mechanical performance and damage tolerance in SiO ₂ , halloysite nanotube, and nanoclay-modified basalt/epoxy composites were reported by Sukur et al. [17]. Kuila et al. [18] found that basalt/epoxy laminates treated with CaCO 3 had improved tensile and flexural strengths. Si ₃ N ₄ was shown to enhance the tensile and flexural characteristics of pineapple/basalt polyester composites by Jesumanen et al. [19]. Improved impact resistance of MWCNT/SiO ₂ -modified basalt/glass epoxy composites was reported by Boobalan and Sathish [20], whereas Alam et al. [21] demonstrated that Al2O3/GNP nanofillers improved interfacial stress transmission, increasing the glass/carbon epoxy composites' hardness and tensile strength. evertheless, most of the literature currently in publication has focused on the tensile, flexural, impact, and durability-related aspects of ceramic/nanoparticle modification in basalt-based or other hybrid fiber composites. Alkali-treated hemp/basalt hybrid epoxy composites containing Si 3 N ₄ nanoparticles have not been thoroughly studied, especially when it comes to evaluating interlaminar shear strength, flexural performance, and K IC at the same time. Furthermore, it is yet unclear how Si ₃ N ₄ addition and fiber surface treatment affects interfacial integrity, damage development, and crack-growth resistance. To close this gap, the current study assesses the mechanical and fracture response of a surface-modified hemp/basalt/Si 3 N ₄ epoxy multiscale composite system. N OVELTY AND PURPOSE OF THE CURRENT STUDY n this context, the present study will focus on the effects of Si ₃ N ₄ nanoparticle incorporation into alkali treated hemp/silane treated basalt fabric-reinforced epoxy hybrid composites with special attention to interlaminar shear strength (ILSS), flexural strength and K IC . The novelty of the work is related to the systematic combination of surface treated hemp and basalt fabrics with different contents of Si ₃ N ₄ nanoparticles and assessing their synergistic effect on the bond at the interfaces, as well as the efficiency of load transfer and crack propagation resistance. The mechanical response and fracture mechanisms are studied as a function of Si ₃ N ₄ content to find the best concentration of nanoparticles. Specific focus is placed on the dispersion of nanoparticles, adhesion of fibers to a matrix, stress transfer and crack growth resistance. The multiscale reinforcement approach of the combination of individual reinforcement and surface-treatment strategy is designed to enhance the structural integrity and damage tolerance of the hemp/basalt epoxy hybrid composites. Materials he epoxy matrix system was composed of HY951 hardener, an aliphatic amine produced from triethylene tetramine (TETA), and LY556 epoxy resin, a diglycidyl ether of bisphenol-A (DGEBA). Huntsman Advanced Materials India Pvt Ltd., located in Mumbai, India, provided both parts. With a viscosity of 10,000–12,000 mPa·s, the LY556 resin makes it easier to wet and impregnate fibers during composite construction. The cured LY556/HY951 combination has a Young's modulus of 2.85 GPa and a tensile strength of about 60 MPa. Resin and hardener were used in the manufacturer's recommended proportions of 10:1 to ensure complete cure under ambient conditions for optimum composite properties. Fiber reinforcement The reinforcement phase consisted of bidirectional plain-weave hemp and basalt fabrics. Metro Composites provided the hemp fabric, and Funique Composites Pvt Ltd. provided the basalt fabric. The areal density of both textiles was 200 g/m². Basalt fibers, with a tensile strength of 2950 MPa and a Young’s modulus of 89 GPa, were incorporated to enhance the stiffness, strength, and thermal stability of the composites. Hemp fibers offered lightweight, renewable reinforcement with a density of 1.45 g/cm³ and a Young's modulus of 30–70 GPa. These woven fabrics used in this study can be seen in Fig. 1. The basalt fabric had a more homogeneous and structurally regular appearance, whilst the hemp fabric had a naturally occurring organic texture. Both reinforcements were anticipated to facilitate successful interfacial adhesion due to their strong compatibility with polymeric matrix. Hemp fibers were alkali-treated with NaOH prior to laminate production, while basalt fibers were silane-treated to improve fiber–matrix bonding and decrease moisture absorption. N I T R ESEARCH GAP M ATERIALS AND METHODS

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