Isolation and characterization of cellulose nanofibers from four plant cellulose fibers using a chemical-ultrasonic process

Cellulose nanofibers (CNFs) were isolated from four kinds of plant cellulose fibers by a chemical-ultrasonic treatment. The chemical composition, morphology, crystalline behavior, and thermal properties of the nanofibers and their intermediate products were characterized and compared. The CNFs extracted from wood, bamboo, and wheat straw fibers had uniform diameters of 10–40 nm, whereas the flax fibers were not uniformly nanofibrillated because of their initially high cellulose content. The chemical composition of each kind of nanofibers was mainly cellulose because hemicelluloses and lignin were significantly removed during chemical process. The crystallinity of the nanofibers increased as the chemical treatments were applied. The degradation temperature of each kind of nanofiber reached beyond 330 °C. Based on the properties of the CNFs, we expect that they will be suitable for use in green nanocomposites, filtration media and optically transparent films.