Effects of alkali treatment on the mechanical and thermal properties of sisal/cattail polyester commingled composites

Abstract

Environmental and energy conservation pressure has led to a dramatic increase in the need for economically feasible lightweight materials that can be better substitutes for non-biodegradable materials in reinforced composites. In this study, the mechanical and thermal properties of polyester resin composites hybridized with a blend of untreated and alkali treated sisal (Agave sisalana) and cattail (Typha angustifolia) fibers were evaluated. Composites were fabricated by a hand lay-up technique at an optimal hybrid fiber weight fraction of 20 wt% and a constant sisal/cattail fiber blend ratio of 75/25. Flexural, tensile, compressive and impact strengths and moduli, as well as thermal conductivity of the composites, were evaluated following ASTM and ISO test methods. Analytical results indicated that alkali pre-treatment of the fibers enhanced the mechanical properties of the hybrid polyester composites though only marginal differences were recorded in the thermal conductivity of the composites fabricated with treated and untreated fiber blends. Morphological examination revealed that the major failure modes were fiber pull-outs and fiber fracture in composites fabricated with untreated and treated fiber blends, respectively. The composites produced could find non-structural applications as ceiling boards, electronic and food packaging materials but their properties such as wettability, crystallinity, flammability and other thermal properties need to be further investigated.

Mechanical Properties of Sisal/Cattail Hybrid-Reinforced Polyester Composites

“…us, the current study augments previous studies which indicated that hybridization of natural fibres in polymer composites improves the mechanical properties of the resultant composites [9,17,31,36,37].…”

“…Flexural, tensile, and compressive strengths of cattail/ polyester composites were much lower compared with sisal/ polyester composites. is trend can be explained by the fact that tensile properties of sisal fibres are higher than those of cattail fibres and thus implying that the reinforcing effect of sisal fibres in the matrix is better than that of cattail fibres (Figure 8) [17]. It was also noted that the diameter of the sisal fibre was less than that of the cattail fibre, and therefore, the surface area of the fibre exposed to the matrix is higher in sisal/polyester composites than in cattail/polyester composites [17,29,30].…”

“…However, there was a drop in flexural, tensile, and compressive strengths by 15.43%, 15.08%, and 20.58%, respectively, as the hybrid fibre weight fraction increased from 20 to 25%. is could be attributed to the possible poor interfacial bonding between the fibres and the matrix as a result of reduced fibre wetting [17][18][19]. Figure 4 shows a fracture micrograph of the flexural investigation test specimen for the hybrid composite at 25 wt% and a constant (50/50) percentage of sisal/cattail fibre in the hybrid.…”

“…e flexural, tensile, and compressive strengths increased by 62.3%, 88.75%, and 45.24% as the hybrid fibre weight fraction increased from 5 to 20 wt% with the maximum values of 44.92, 31.40, and 23.99 MPa, respectively (Supplementary File 1).ere were significant differences (p < 0.05) between the mean flexural, tensile, and compressive strengths of the composites formed by varying hybrid fibre loadings. is may be attributed to the increase in the amount of fibres as load bearing elements in the composites and their uniform distribution in the matrix as fibre loading increased to 20 wt%.e recorded values could be due to the better fibre-matrix bond resulting from uniform distribution of the fibres and the presence of sisal fibres in the composites(Figure 3)[16,17].…”

Structure-properties relationships in alkaline treated rice husk reinforced thermoplastic cassava starch biocomposites

“…Edhirej et al reported that TPS composites reinforced with untreated bagasse with size of < 300 m exhibited higher tensile strength compared with those reinforced with bagasse sized within 300-600 m [6]. TPS/RH1 and TPS/treated RH1 composites showed similar levels of elongation at break (Figure 8 alkaline treatment points to more effective fiber/matrix load transfer [56,57] as a result of stronger interfacial interactions arising from favorable topological and wetting contributions [58][59][60]. In principle, interface bonding in fiber reinforced composites takes place via electrostatic forces, chemical bonding and mechanical interlocking mechanisms [61].…”