Investigating the effect of pine wood flour dimensions on the thermal and mechanical properties of the resulting composites

This study was conducted to investigate the effect of pine wood flour dimensions on the thermal and mechanical properties of the resulting composites. For this purpose, polyethylene (at a constant level of 50%), pine wood flour (at a constant level of 50%), wood flour dimensions at three levels (40, 70 and 100 mesh), and maleic anhydride bonded to polyethylene at a constant level of 3% were mixed together using a twin-screw extruder (two helices) and standard test specimens were made using the injection molding method. Then, mechanical properties including tensile and flexural strength, tensile and flexural modulus, impact strength, physical properties including water absorption and thickness swelling, and thermal properties and fire retardancy were measured. The results showed that by reducing the flour size to 70 mesh, the tensile strength and modulus, flexural strength and modulus, and impact strength increased by 7.8, 8.5, 9.2, 10.4, and 4.5 percent compared to 40 mesh flour, respectively. By reducing the flour size to 100 mesh, water absorption and thickness swelling decreased by 11.24 and 4.65 percent compared to 40 mesh flour, respectively. By reducing the flour size to 100 mesh, the limited oxygen index increased by 0.7 percent. The residual ash content in the four composite samples when using 40, 70, and 100 mesh flour and pure polymer was 6.87, 7.11, 8.15, and 0.56 percent, respectively.