The Mechanical Properties of Sisal and Loofah Fibres and Their Composites Resulting From the Reinforcement of Epoxy Resins

Abstract

Sisal and Loofah are two amongst a number of natural fibres that are found in Kenya. While Sisal is cultivated commercially in large scale plantations, Loofah grows in the wild. The traditional uses for Sisal fibre include the making of rope, sacks, carpets, bags and cushioning upholstery. Loofah fibre is normally used as washing sponges, pillowing material, filter material for oil presses and for scouring and cleaning machinery. Extensive research has been carried out on the effects of Longitudinally Aligned continuous and Randomly Aligned Discontinuous Sisal fibres on base materials such as Mortar, Cement and Epoxy resin. This research has been conducted within the Departments of technical Engineering and Civil Engineering of the University of Nairobi. Mutuli (1979) carried out research on the mechanical properties of sisal fibre reinforced composites. While his results on the tensile properties conformed with the general theory on fibre reinforced composites, they lacked certain features that would normally arise at low and high fibre volume fractions. otieno and Ogango (1991) carrred out some work on the effects of Loofah fibre on the tensile stress and the tensile strain of Epoxy reSln. Their results however were not conclusive. One of the aims of this research is to determine the effect of fibre volume fraction on the tensile strength, tensile strain, and Elastic Modulus of Sisal reinforced and Loofah reinforced Epoxy resin composites. Comparison of the results from both the existing theory and the present work will be done. The volume fraction at which the composite properties are a minimum or are critical will be identified. The relationship between the Multiple Matrix Fracture (M.M.F.) phenomena and the fibre volume fraction will be determined. The interfacial bond strength and the fibre critical length will also be evaluated. In addition the effects of the varying cross - sectional area of sisal fibre and the differing Poissons ratios of sisal fibre and Epoxy resin matrix will be examined. The present results show that sisal fibre when used to reinforce Epoxy resin does lead to definate improvements in the tensile properties of the matrix. The results also show that designs must be based on specific fibre volume fractions. Within the M.M.F. range, containers for liquids will be regarded as having failed whereas pure structural components may still find use. In contrast, Loofah fibre reinforcement of Epoxy resin results into a reduction of the tensile properties of the matrix.