Surface modification of cellulose nano-fiber and its effect on mechanical properties of nitrocellulose film

Cellulose nano-fibers (CNFs) are prepared by TEMPO-mediated oxidation combined with homogenizing mechanical treatment. The carboxyl groups on the surface of CNFs are removed by an alkalization process. Then CNFs are chemically modified by a mixture of nitric acid and dichloromethane to obtain nitrified CNF (NCNF). NCNFs could readily suspend and well disperse in acetone. The structure and properties of NCNFs are examined using Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), and transmission electron microscopy (TEM). The nano-nitrocellulose composite films with NCNF as reinforcment are prepared by a casting/evaporation technique. The tensile properties of the nanocomposite films are tested. The results show that the tensile strength, Young's modulus, and elongation at break of the nanocomposite films increase simultaneously in comparison with that of neat NC. The influence of cellulose nanowhiskers (CNWs) and CNFs on the tensile properties of nanocomposite films is studied. As reinforcement, CNFs demonstrate higher efficiency compared to CNWs because of their larger aspect ratio.