<![CDATA[Natural fiber composites have potential as lightweight and environmentally friendly materials. This study investigated the effects of sisal fiber immersion time in 5% NaOH solution on the maximum tensile stress, maximum strain, and macrostructural fracture characteristics of polyester-matrix sisal fiber laminate composites. Immersion times were 1, 2, 3, 4, and 5 h, with five specimens per treatment. Tensile testing was conducted according to ASTM D638 Type III using a Universal Testing Machine (UTM), and fracture surfaces were examined using a digital microscope. The highest mean tensile stress was obtained after 3 h of immersion (27.3002 N/mm²), while the lowest occurred after 1 h (17.5245 N/mm²). One-way ANOVA revealed significant differences in tensile stress among treatments (F(4, 20) = 12.3808, p = 0.0000315), and Tukey HSD identified significant differences between several group pairs. The highest mean strain was also observed after 3 h (8.4982%); however, Welch’s ANOVA indicated no significant differences among treatments (F(4, 9.50) = 1.2120, p = 0.3675). Signal-to-noise (S/N) analysis yielded the highest values at 3 h for tensile stress and strain, at 28.5245 dB and 17.6453 dB, respectively. Macroscopic observations revealed voids in specimens immersed for 1–2 h and fiber breaking in those immersed for 3–5 h. Overall, 3 h of immersion produced the highest mean tensile stress and strain, although significant differences were found only in tensile stress.Keywords— Sisal fiber, NaOH treatment, tensile stress, strain, fracture characteristics..]]>
Copyrights © 2026
