Naturally based intraply hybrid composites

Abstract

Natural fibre composites consisting of natural fibres as the reinforcement and a biobased matrix are becoming increasingly popular alternatives to synthetic fibre composites. Popularity in the use of natural fibres to manufacture composites has increased due to various factors such as the benefits of natural fibres over synthetic fibres and, regulations and guidelines which require the use of more sustainable and eco-friendly materials. The study investigated the effect on material properties when hybridising sisal and flax fibres to produce intraply and intrayarn configurations as compared to non-hybrid woven sisal configurations. Intrayarn(tr)-S/F consisted of a treated intrayarn configuration made up of locally extracted sisal fibres spun with double ply flax yarn as the warp and single ply flax yarn as the weft. Intraply(tr)-S/F consisted of a treated hybrid configurations with sisal twine as the warp and double ply flax yarn as the weft. While, Intraply(untr)-S/F consisted of an untreated hybrid configuration with sisal twine as the warp and single ply flax yarn as the weft. The configurations were prepared and tested according to ISO 527-4:2023. Analysis of the tensile results indicate that Intraply(untr)- S/F had the highest tensile properties at a Young’s modulus, Poisson’s ratio and tensile strength of 6.95 GPa, 0.408 and 83.7 MPa respectively. Furthermore, the intraply and intrayarn configurations had higher tensile properties than the woven configurations. However, the fibre volume percentages varied significantly where, Intraply(untr)-S/F had an increase of 38.72 per cent, 52.25 per cent in Young’s modulus and tensile strength respectively from Intraply(tr)-S/F. The variation in tensile properties is due to a 9.32 per cent difference in fibre volume percentage. The predicted tensile properties of the configurations at a fibre volume percentage of 20 per cent indicates that Intrayarn(tr)- S/F would have superior tensile properties with a tensile modulus, tensile strength and Poisson’s ratio of 9.30 GPa, 109 MPa and 0.345 respectively. Moreover, the study also investigated the material and physical properties of treated configurations with 2 wt.% NaOH and untreated configurations. Moisture content analysis of the configurations indicates that moisture content decreases after treating with 2 wt.% NaOH as observed for Intraply(tr)-S/F and Wov(tr)-S with a decrease of 0.07 per cent and 0.65 per cent respectively. Furthermore, as the moisture content decreases the tensile properties are improved as observed for Intraply(tr)-S/F, Intraply(untr)-S/F and Intrayarn(tr) with low moisture contents of 8.19 per cent, 8.26 per cent and 8.78 per cent respectively.