Investigation of physical and mechanical properties of nano-pulverized cellulose nanofiber preform sheets for CNF thermoset nanocomposites application

Abstract

To study the physical and mechanical properties of nano-pulverized cellulose nanofiber (CNF) sheets, CNF sheets were prepared by vacuum filtration and solvent exchange—hot press technique with different concentrations of CNF, respectively. The microstructures as well as the mechanical properties of the corresponding CNF sheets were investigated, and low density and high porosity of the solvent-treated CNF sheets were shown. Porosity of the CNF sheets was successfully controlled using solvent with different concentrations of CNF. The porous structure of the CNF sheet was investigated by field emission scanning electron microscopy (FE-SEM). Structural changes were observed as a consequence of solvent exchange method. Tensile strength and elastic moduli of solvent-treated CNF sheets were lower than those of water-dried CNF sheets due to the solvent exchange method. The physical and mechanical properties of solvent-treated CNF sheets are better than those of many thermoplastics. The resin impregnation of solvent-treated CNF preforms was successfully demonstrated. The resin impregnation condition of solvent-treated CNF preform sheets were observed by using FE-SEM. The tensile strengths and Young’s modulus of CNF/epoxy films were higher than those of the solvent-treated cellulose nanofiber preform sheet.