Correlations between rheological behavior and intrinsic properties of nanofibrillated cellulose from wood and soybean hulls with varying lignin content

Effects of raw material and chemical composition were considered relative to the intrinsic properties and the rheological behavior of nanofibrillated cellulose aqueous suspensions (CNFs). Atomic force microscopy, Fourier-transform infrared spectroscopy, surface chemistry analysis, thermal gravimetrical analysis, and zeta-potential were used to study the morphology, chemical composition, charge density, as well as thermal and colloidal stability of the different CNFs. Regarding the rheological properties of the samples, steady-state and oscillation studies of the CNF aqueous suspensions obtained from wood and soybean hulls were performed. An interesting correlation was found between the rheological behavior of CNF suspensions and their intrinsic properties. Soybean CNF presented lower viscosities than wood samples, which could be related to their morphology and charge density. Additionally, unbleached soybean CNF (sb-LCNF) showed yield stress compared with the other samples, which could be attributed to the presence of pectin. Furthermore, the different chemical compositions between the samples affected their thermal properties, as well as on their crystallinity.