Preparation, morphology and structure of cellulose nanocrystals from bamboo fibers

Bamboo cellulose nanocrystals (CNCs) were successfully prepared from the sulfuric acid hydrolysis of bamboo bleached fibers. Reaction parameters such as temperature, acid-to-pulp ratio and hydrolysis time were varied over a limited range and conditions for the preparation of individual bamboo nanorods with a yield of 30 % were identified. The characteristics of bamboo CNCs were compared with those of CNCs obtained from three other sources, namely eucalyptus, sisal and curauá, prepared using already reported conditions. The shape and size of all four types of CNCs were investigated by complementary techniques, namely transmission electron microscopy, atomic force microscopy, dynamic light scattering and X-ray diffraction. The surface charge of the nanocrystals was determined by conductometric titration and zeta potential measurements. In all cases, negatively charged ribbon-like nanoparticles constituted of a few laterally associated elementary crystallites were observed. The influence of the reaction parameters on the CNC characteristics was discussed and compared with the data reported in the literature.