Problem definition and objectives: Given the importance of environmental issues and the need to use sustainable materials, the production of composite materials from natural substances and polymers has become a key topic in industrial research. Ash wood flour, as a natural resource with suitable mechanical properties, and polypropylene, as a widely used polymer, can effectively contribute to the creation of high-quality composites. However, one of the main challenges in this field is improving the mechanical, thermal, and flame-retardant properties of these composites. Nanoclay, as a reinforcing agent, can be effective in this regard, but further research is needed to understand its effects on various properties of the composites. The primary objective of this study is to investigate the impact of nanoclay on the mechanical, thermal, and flame-retardant properties of composites made from ash wood flour and waste polypropylene.
Methodology: To this end, polypropylene (at a fixed level of 50%), ash wood flour (at a fixed level of 50%), nanoclay (at four levels of 0, 2, 4, and 6 weight percent), and maleic anhydride grafted polypropylene at a fixed level of 3% were mixed together using a twin-screw extruder. Standard test samples were then produced using the injection molding method. Subsequently, mechanical properties, including tensile and flexural strength, tensile and flexural modulus, and impact resistance, as well as thermal and flame-retardant properties, were measured.
Results: The results indicated that the addition of nanoclay to the composite made from ash wood flour and waste polypropylene leads to improvements in mechanical, thermal, and flame-retardant properties, which can have diverse applications in various industries. Increasing the nanoclay content to 2% resulted in increases in tensile strength, tensile modulus, and flexural modulus of 7.9%, 6.3%, and 4.6%, respectively. An increase in nanoclay to 4% led to a 5.6% increase in flexural strength. However, raising the nanoclay content to 6% resulted in a 20.5% decrease in impact resistance and a 4.7% increase in the oxygen index. Additionally, thermal stability increased with the addition of nanoclay up to 6%, and a greater amount of char was retained.
Conclusion: The addition of nanoclay to the composite significantly enhances its tensile and flexural strength and modulus. This improvement results from the uniform distribution of nanoclay within the matrix and the strong bonding created between the nanoclay and the polymer matrix. Furthermore, nanoclay enhances the thermal resistance of the composite due to its layered structure, which improves heat transfer pathways. In terms of flame retardancy, nanoclay reduces the rate of combustion, as it forms a protective silicate layer during combustion that prevents the release of gases and flammable materials. Overall, incorporating nanoclay into composites made from ash wood flour and waste polypropylene leads to improved mechanical, thermal, and flame-retardant properties, which can provide diverse applications in various industries.