Mechanical properties of laminated composites reinforced by natural fibers of ‎cotton, wool and kenaf under tensile, flexural and shear loadings

The increasing need for manufacturing of eco-friendly products has led researchers to explore the possibility of using of natural fibers in ‎the fabricating of composites. In the current study, plain-woven plant fibers of cotton and kenaf, and animal fiber of wool with were used ‎as the reinforcement of epoxy-based laminated composites. Moreover, in order to evaluate the mechanical properties of the natural fibers ‎reinforced laminated composites, plain-woven E-glass/epoxy composites were also manufactured. The mechanical properties of the ‎samples subjected to tensile, shear and flexural loadings were determined. The results showed that the fraction of the specific tensile ‎strength of the cotton/epoxy laminates to laminates reinforced by kenaf or wool fiber is equal to 1.71 and 4.47, respectively. Under shear ‎loading, the specific strength of the samples was also 1.24 and 2.45 times greater by changing the kenaf and wool fibers to cotton fiber, ‎respectively. In addition, the specific flexural strength of the cotton/epoxy composites was respectively obtained 1.42 and 2.34 times ‎greater than that of the kenaf/epoxy and wool/epoxy composites. Moreover, the specific energy absorption related to the cotton/epoxy ‎laminated composites under tensile loading is 2.7 times greater than that of the glass fiber reinforced laminated composites. At the end, in ‎order to measure the amount of water absorbed by different samples, moisture absorption test was also carried out at intervals of 3 and ‎‎10 days. It was revealed that the greatest percent of the water absorption (7.47%) is related to the cotton reinforced specimen at interval of ‎‎10 days‎.