Production and investigation of the mechanical properties of nanoclay and walnut shell filled polymer composites

In today's technology, natural fibers combined with various inorganic and organic additives are preferred in the production of polymer composites, also known as biocomposites, to enhance the properties of polymer materials. Natural fibers offer numerous advantages such as low cost, high physical and mechanical strength, sustainability, and being derived from renewable resources. These fibers are mixed with plastics in various proportions to create plastic-composite materials. For this purpose, agricultural wastes (such as wheat straw, rice straw, hemp fiber, walnut shell, hazelnut shell, and various dry fruit shells) are extensively used as reinforcement materials in biocomposite production. Hybrid composites are also produced by adding both organic and inorganic additives to the polymer matrix. Hybrid composites are defined as materials obtained by combining different types of materials within the same matrix. These composites offer properties that cannot be achieved with a single reinforcement material alone. The hybridization of filler materials with different geometries and sizes provides some advantages over using them individually in a polymer matrix. Due to their effect on improving mechanical properties, hybrid composites attract the interest of many researchers. These composites consist of organic (cellulose-based) and inorganic (mostly mineral) filler materials. Walnut shell (WS), with its characteristic color, hardness, and cellulosic structure, is a highly suitable material for the production of these composites. Walnut production is abundant in Turkey. After the walnut kernel is extracted, the remaining WS is typically burned and does not generate additional value for the farmer. Given the abundance of walnuts in Turkey and the ease of processing, WS can be used as a natural filler additive in biocomposites. In this study, biocomposites will be produced using high-density polyethylene (HDPE) as the matrix material and various proportions of WS and nanoclay as reinforcements. The effect of the combined use of WS and nanoclay on the mechanical and thermal properties will be determined, and the resulting microstructures will be observed using SEM.