Effect of span length on the tensile properties of natural fibers

Natural fibers are widely used as “reinforcing agents” in polymer composites. The aim of the current study is to evaluate the effect of span length on the tensile properties of several natural fibers (Vietnamese coir and bamboo and Bangladeshi jute). Tensile testing of jute, bamboo and coir fibers was carried out by varying span length (5, 10, 15, 25 and 35 mm). The Young’s modulus and strain to failure were corrected by using newly developed analytical equations in order to correlate the Young’s modulus and strain to failure of natural fibers. Scanning electron microscopy of the fibers was also carried out. It is clearly observed that the Young’s modulus increased with an increase in span length. Whereas tensile strength and strain to failure decreased with an increase in the span length of single fibers. The correction method resulted in a high Young’s modulus for larger span, while strain to failure found was lower compared to smaller span. This is because larger span length helps to minimize the machine displacement compared to smaller ones. Among all fibers, the Young’s modulus of bamboo fiber was highest, followed by jute and coir respectively. Jute fiber had smoother surface and compact structure compared to other two fibers.