Comparison of analytical assessment of composite properties utilizing short discontinuous bamboo fibers

Abstract

Due to interest in sustainable materials, natural fibers are increasingly being utilized as a reinforcement in composite materials. Moreover, natural fiber composites have been found to offer benefits such as reduced weight and costs. Recent advances have allowed for improved extraction and conversion of natural materials into useful fiber architectures. While studies have shown that these natural fiber composite properties are quite competitive, a reduced matrix bond strength and a hydrophilic nature have been associated with this class of fiber. As such, there is a need to understand the fiber/matrix interaction by establishing relationships toward predicting response of bamboo fiber composites for use in design of industrial applications. Two main parameters, fiber volume fraction and critical fiber length, must be known to allow for production and appropriate design of bamboo fiber materials and composites. Baseline tensile tests on polypropylene compounded with untreated bamboo were performed determining strength and modulus with significant fiber pullout noted. Several additives and surface treatments were utilized and were effective at improving composite performance allowing for correlations between fiber volume fraction with strength and stiffness to be established. Next, existing analytical models were applied to the baseline bamboo/polypropylene composites toward establishing the effectiveness of each at predicting composite properties. While several models predicted composite response marginally well, strength and stiffness appeared to be impacted differently by changes in fiber-matrix interfacial shear strength (IFSS). Based on these results and the relationship between IFSS and critical fiber length, a method for determining critical fiber length is investigated.