Flexural Characterization of Hybrid Palm/Glass Fibers-Reinforced Epoxy Composites

Abstract

Natural fiber-reinforced polymer composites are commonly weak in tension causing failure initiated at their tension side when being loaded in flexure. In order to improve such composite beam performance, palm fiber of tension side of such beams has been substituted with E-glass fiber to produce hybrid palm/E-glass fibers-reinforced epoxy composites, and their flexural stress-strain response and failure have been studied. Palm fiber was obtained from local sugar palm trees while the E-glass was selected due to its low cost and availability, and epoxy was used as matrix. Whilst the palm fiber was undergone alkaline treatment, rinsing, slow drying and chopping into ~20 mm long prior to being embedded in the matrix, the E-glass fiber was arranged longitudinally such that its tensile strength can optimally be harnessed.  Composite plates with five different hybrid ratios of 0.0, 0.1, 0.2, 0.3, and 0.4, have been fabricated, cut into specimens and tested in three-point bend loading configuration in accordance with the ASTM D790 standard using span-to-depth ratios of 16, 24 and 32.  Composite plates were fabricated using hand lay-up and press mold techniques. The specimens were cut from the plates using a diamond-tipped circular saw blade rotating at ~6000 rpm. It was revealed that (i) longer beams exhibited higher flexural but lower strain-to-failure,  (ii) flexural strength increases with the increase of glass fiber content, (iii) shorter beams, S/d = 16, demonstrate a decrease in flexural strain to the contrary of longer beams, S/d = 24 and S/d = 32, with the increase of glass fiber content.