Preparation of spherical nanocellulose from Gai bamboo and mechanical properties of chitosan/nanocellulose composite

In this study, spherical cellulose nanocrystals have been extracted from Gai bamboo (Bambusa blumeana) fibers by sulfuric acid hydrolysis methods. The removal of amorphous components, lignin, and hemicellulose in raw bamboo fiber and the incorporation of sulfate groups were explored via the changes of bond's vibration in Fourier-infrared spectra and the decrease of onset temperature of thermogravimetric diagram. The results from transmission electron microscopy and X-ray diffraction revealed that the nanocellulose has a spherical shape with a diameter of 2 to 10 nm and the crystallization index of 70.30% and crystallization degree of 0.77. The improvement of thermal and mechanical properties of the chitosan films loaded with spherical nanocellulose were evaluated. Interestingly, the tensile strength, modulus, and elongation at break for chitosan film loaded with spherical nanocellulose were all increased. The highest value achieved with chitosan film containing nanocellulose of 2 phr. The increase values of tensile strength, modulus and elongation at break were of 63%, 207 MPa, and 30%, respectively. In addition, the moisture absorption of the chitosan film was decreased to 20% indicating that the barrier properties have improved. These improvements illustrated the advancement of nano sized of spherical nanocellulose and the chemical compatibility between nanocellulose and chitosan that resulted in well-dispersion of nanocellulose in chitosan matrix, developed high performance bionanocomposite.