Strength evaluation of alkali treated Sabai Grass ( Eulaliopsis binata ) fibers and its reinforced composites

Abstract

This investigation aims to use Sabai grass fiber as a substitute reinforcement in epoxy-based composite systems, which is environment friendly and performs similarly to other natural fibers. Composite laminates are prepared with treated and untreated Sabai fibers reinforcement layered in different orientations using vacuum resin transfer molding method. Fabricated composite laminates have been evaluated for their mechanical properties (tensile strength, flexural strength, and impact strength). The effect of varying concentrations (3%, 5%, 7%, and 9 wt.%) of NaOH treatment and fiber reinforcement angle on Sabai fiber-reinforced composite laminates on its physical and mechanical properties are experimentally evaluated. The specimen made with 5 wt.% of NaOH-treated has shown maximum tensile properties because of the higher fiber concentration in the composite laminate. The thickness of fibers gets reduced as the central voids contract after the treatment. The treated strand reinforced (0°/0°/0°/0°) composite laminate has maximum tensile (103.15 MPa) and flexural strength (143 MPa). In addition, it has a higher density (1.20 g/cm³) and less porosity contents (0.70%). The untreated reinforcement has a higher impact strength. The adhesion mechanism at the fiber matrix interface has been studied using field emission scanning electron microscopy by analyzing the fiber surface morphology after treatment and in the fractured samples. The correlation of the mechanical properties of the laminate has been discussed with consideration of interfacial adhesion mechanism, fiber pull-outs, and fiber-matrix cracking phenomenon. FTIR analyses confirm the removal of the peak at around 1735 cm⁻¹ that belongs to the acetyl group of hemicellulose attributed to C=O stretching vibration, and the peak at 1253 cm⁻¹ is associated with the lignin, which is in close agreement with chemical analysis.