Issue 78

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

Figure 1: Photographs of plain weave woven fabric reinforcements: (a) Hemp, (b) Basalt.

Nanofiller reinforcement Ceramic nanofillers were silicon nitride (Si ₃ N ₄ ) nanoparticles (20–45 nm, 99.9% purity; Sigma-Aldrich, MERCK, Product No. 334103). Because of its exceptional hardness, wear resistance, and thermal stability, Si ₃ N ₄ was chosen. Agglomerated, irregular nanoparticles with clustered shape are visible in SEM images (Fig. 2).

Figure 2: Si 3 N ₄ nanoparticle SEM micrographs at two different magnifications: (a) 3,000× and (b) 15,000×. Figs. 2a and 2b show the SEM morphology of the as-received Si 3 N 4 powder at magnifications of 3,000x and 15,000x, respectively. High-surface-area ceramic powders are characterized by irregularly shaped, agglomerated nanoparticles with fine clustered characteristics, as shown in micrographs. This type of morphology helps to improve the filler-matrix interfacial contact, which in turn improves stress transmission and reinforces the composite system's efficiency. Alkali modification of hemp fabrics Hemp fabrics were treated with a 5 wt.% sodium hydroxide (NaOH) solution to enhance interfacial adhesion between the fibers and the epoxy matrix. This alkali treatment removed non-cellulosic impurities—including hemicellulose, lignin, waxes, and pectin—yielding a cleaned, roughened surface with partial fibrillation. These modifications increased fiber wettability, exposed reactive hydroxyl groups, and promoted mechanical interlocking and interfacial bonding, thereby facilitating more efficient stress transfer. A 5 wt.% concentration was selected because it effectively optimizes interfacial properties without compromising cellulose structure or fiber mechanical integrity [3]. Silane modification of basalt fabrics The basalt fabrics were treated with 1 wt.% of silane coupling agent to strengthen the fiber–matrix interface. The silane treatment introduced functional groups on the surface of the basalt fiber which promote stable chemical bonding with the epoxy matrix and enhance the wettability. Consequently, this minimized interfacial defects, enhanced fiber–matrix stress

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