A Comparative Study on the Mechanical Properties of Different Natural Fiber Reinforced Free-Rise Polyurethane Foam Composites

The goal of this study was to improve tailored mechanical properties of foam by incorporating different filler types. Flexible polyurethane foam thermosets with varying wt % of natural fibers were tested and characterized according to their mechanical, morphological, and thermal properties. The fillers used included lignin, chitin, chitosan, hazelnut shells, and polysaccharide, and the results were investigated to compare the effects of fillers on the foam properties. A morphological analysis showed good overall dispersion of chitin and hazelnut fillers and consequent improvements in tensile and tear strength of polyurethane foam. Additionally, these fillers helped increase resiliency while reducing foam hardness. Polysaccharide showed similar improvements in tensile results, while the tear strength decreased. However, lignin and chitosan reduced foam mechanical properties, which suggested low compatibility of these fillers (in pretreated form) with polyurethane foam. Based on the results, these fillers can be incorporated into polyurethane foam to fabricate more sustainable and ecofriendly thermoset polyurethane foams for industrial applications, such as the production of mattresses, car seats, and insulating material in construction or textile products, as well as in the cosmetic industry.