Tensile behavior of high performance natural (sisal) fibers

Environmental awareness and an increasing concern with the greenhouse effect have stimulated the construction, automotive, and packing industries to look for sustainable materials that can replace conventional synthetic polymeric fibers. Natural fibers seem to be a good alternative since they are readily available in fibrous form and can be extracted from plant leaves at very low costs. In this work we have studied the monotonic tensile behavior of a high performance natural fiber: sisal fiber. Tensile tests were performed on a microforce testing system using four different gage lengths. The cross-sectional area of the fiber was measured using scanning electron microscope (SEM) micrographs and image analysis. The measured Young's modulus was also corrected for machine compliance. Weibull statistics were used to quantify the degree of variability in fiber strength, at the different gage lengths. The Weibull modulus decreased from 4.6 to 3.0 as the gage length increased from 10 mm to 40 mm, respectively. SEM was used to investigate the failure mode of the fibers. The failure mechanisms are described and discussed in terms of the fiber microstructure as well as defects in the fibers.