Evaluation of mechanical properties of both benzoyl peroxide treated and untreated teak sawdust reinforced high density polyethylene composites

Natural fiber reinforced polymer composites are extensively used in various applications such as automotive interiors, furniture, packaging and construction materials. In the present work, teak or shegun (Tectona grandis) sawdust were used as reinforcements in thermoplastics. Sawdust fibers were chemically treated to reduce their moisture absorption. Sawdust pretreated with alkali was then treated with benzoyl peroxide to provide a more hydrophobic surface that would adsorb less water and have better interfacial adhesion. Reaction parameters such as time, temperature, pH and concentration of benzoyl peroxide were used to get the desired change in functional group of cellulose. FT-IR spectroscopic analyses were done and the results showed the evidence of positive reactions. In this work, chemically treated and untreated teak sawdust reinforced high density polyethylene (HDPE) composites were prepared by compression moulding technique. The effects of this chemical treatment on the physico-mechanical properties of the composites were studied. The effect of fiber content on the physico-mechanical properties of composites were also studied by preparing the composites with different weight fractions (5, 15, 25, 35 and 45%) of sawdust. Water absorption (%) tests for all composites revealed that there was less water absorption for the treated composites than the untreated ones. Scanning electron microscopy (SEM) images of treated and untreated sawdust-HDPE composites showed that better interfacial adhesion has occurred between the fiber and the matrix in benzoyl peroxide treated sawdust-HDPE composites. Mechanical properties (tensile strength, elongation at break and impact strength) were determined and analyzed for all treated and untreated sawdust-HDPE composites. Improved tensile and impact results of treated sawdust-HDPE composites indicated that benzoyl peroxide treatment of sawdust increases the interfacial adhesion between fiber-matrix in the treated sawdust-HDPE composites.