Issue 78

N. Nayak et alii, Fracture and Structural Integrity, 78 (2026) 378-392; DOI: 10.3221/IGF-ESIS.78.22

Figure 12: SEM micrograph of alkali-treated powder sisal fibre reinforced polypropylene composite at 20 wt.% fibre loading.

Figure 13: SEM micrograph of untreated powder sisal fibre reinforced polypropylene composite at 20 wt.% fibre loading.

SEM observations confirmed improved fibre embedding, reduced fibre pull-out, fewer interfacial gaps and lower void concentration in the alkali-treated composites. These features support the measured improvements in tensile, flexural and impact properties and reinforce the role of interfacial adhesion in governing composite performance.

C ONCLUSIONS

T

his investigation evaluated alkali-treated sisal fibre reinforced polypropylene composites through mechanical testing, dielectric characterization, SEM examination and Response Surface Methodology. The main conclusions are as follows:  Sisal fibre reinforced polypropylene composites were successfully fabricated by compression moulding, and the selected experimental design enabled systematic evaluation of fibre treatment, fibre length and fibre loading.  Alkali treatment improved fibre–matrix compatibility by removing non-cellulosic surface constituents and increasing fibre roughness, which enhanced mechanical interlocking, reduced fibre pull-out and improved stress transfer.  Mechanical performance was strongly influenced by fibre loading and fibre length. Moderate reinforcement improved tensile, flexural and impact responses, whereas excessive loading or excessive fibre length reduced performance because of poor dispersion, void formation and localized stress concentration.

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