Comparison of the effect of walnut shell and charcoal flour on the characteristics of wood-plastic composites

In this study, the effect of walnut shell and charcoal flour on the applied characteristics of the resulting plastic composites was investigated. For this purpose, walnut shell and charcoal flour in three levels of 20, 30 and 40% were mixed with high density polyethylene using Brabender internal mixer during the melt mixing process, then standard test samples were made by injection molding method. Mechanical properties including tensile and flexural strength, tensile and flexural modulus and impact strength were measured. Physical properties including water absorption and thickness swelling after 24 hours immersion were evaluated and scanning electron microscopy images were also examined. The results showed that the flexural strength and impact strength of the wood plastic composite containing 40% walnut shell flour were higher than the samples containing 40% charcoal flour. Also, by increasing the walnut shell and charcoal flour from 20 to 30%, the flexural strength increased by 3.3% and 6.1%, respectively, and by increasing the walnut shell and charcoal flour from 20 to 40%, the flexural modulus increased by 51.9% and 63.8%, respectively. Other results of mechanical strength indicate that with increasing walnut shell charcoal from 20 to 40%, tensile strength and modulus increased to 22.9 and 109.7%, respectively, and with increasing walnut shell and charcoal flour from 20 to 40%, the impact strength decreased by 6.6 and 5.4%, respectively. The results of physical properties showed that with increasing walnut shell and charcoal flour from 20 to 40%, water absorption for 24 hours decreased by 19.2 and 8.4%, respectively, and thickness swelling by 24 hours decreased by 53.6 and 46.7%, respectively.