Effect of the Fiber Equivalent Diameter on the Elastic Modulus of Eucalyptus Fibers

Environmental, economical, societal and technical advantages are today favoring natural lignocellulosic fibers over glass fiber. However, natural fibers are not as uniform in their dimension and properties as compared to synthetic ones. In recent works, it was found that the variation in strength could be correlated to the diameter for several lignocellulosic fibers, including that obtained from the eucalyptus wood. The present work investigated a possible correlation of the diameter with changes in the elastic modulus of eucalyptus wood fibers. Precise measurements of the equivalent diameter, conducted in a profile projector, were correlated with the elastic modulus by means of the Weibull statistic analysis. The results showed that an inverse correlation with the diameter applies for the elastic modulus with a reasonable degree of precision. SEM observation of the eucalyptus fiber, both it its structure and fracture aspects, strongly indicates that defects and microfibrils participation could be responsible for the inverse correlation.