A novel hybrid polyurethane composites with ZnO particles and sheath palm residues: Synergistic effect

Abstract

AbstractTechnological advances related to the development of new sustainable materials have driven the search for composites containing green fillers. Polyurethane (PU) composites with natural fibers have stood out; however, these materials have limited mechanical and thermal properties. This study developed hybrid PU composites filled with ZnO and palm sheath residues and evaluated the fiber loading (0, 5, 10, 15, and 20 wt%) on morphological, chemical, thermal, crystalline, and mechanical properties. Microscopic and scanning electron microscopy images showed that ZnO promoted homogeneous and isotropic cell structures. Sheath palm residues were well dispersed throughout the PU matrix and increased the foam's density and further decreased the cell sizes due to limited expansion caused by the fibers that altered nucleation and growth mechanisms. Strong hydrogen bonds formed between the fillers and the PU matrix resulted in a new network that improved thermal resistance. Also, crystallinity enhanced PU chains' organization due to filler incorporation, and these changes on the PU matrix increased impact resistance. The best results were obtained for the hybrid PU composite with 20 wt% of palm fiber. The properties improvements show the reinforcements' character in PU foams with environmentally friendly materials.