Determination of the Bending Strength and Hardness Values of Sisal Fiber Reinforced Polyester Composites

Abstract

The growing environmental consciousness and understanding of the need for sustainable development has generated interest in the use of natural fibers as reinforcements in polymer composites to replace synthetic fibers such as glass. The aim of this study was to determine the bending strength and hardness values of composite samples from sisal fibers and unsaturated polyester resin as the matrix. Chopped random sisal fibers were mixed with resin at various fiber weight percentages from 5, 10, 15, 20 to 40% sisal fiber. Hand lay- up and cold compression processes were used to produce test samples which were left to cure at 250C. The test samples were supported on knife edges and a roller edge central load applied on them for the three-point bend test. The hardness of the samples was tested on a Vickers micro-hardness testing machine. Results show that the 30%wgt fiber content had the highest value of 51.062 MPa for bending strength properties and 16.1 for hardness value while the unmodified sisal fibers recorded a bending strength of 40.382 MPa and a hardness value of 15 at the same fiber content. The modified sisal fiber has a better bonding between the fibers and matrix compared to unmodified sisal fiber therefore the composite samples could bear more load. It was also observed that surface modification of plant fibers result in superior bonding of the fibers and matrix. Sisal leaves produces fibers that could be used in composite manufacturing for use in roofing, partitioning and furniture applications.