A COMPARATIVE STUDY OF MICRORHEOLOGY OF NANOCELLULOSE PRODUCED FROM CORN STOVER USING DIFFUSING WAVE SPECTROSCOPY (DWS) AND MECHANICAL RHEOMETRY

Agricultural waste corn stover has very little value, but can be a good renewable, biodegradable, and inexpensive source to produce value-added products, such as cellulose and nanocellulose. The properties and functions of cellulose and nanocellulose depend on the cellulose source and preparation process. The microheterogeneity and microrheological properties of corn stover nanocellulose (CSNC) solutions were investigated by a novel technique named diffusing wave spectroscopy (DWS); and both DWS and mechanical rheometry measurements for the prepared CSNC were compared and analyzed. We expected that the DWS study of the CSNC could reveal some new insight into the CSNC properties. It is also expected that the microrheological behavior of CSNC measured by DWS should be matched with the data measured by conventional mechanical rheometry. By comparing the meansquare displacement (MSD) of the microbeads embedded in five concentrations of CSNC solutions measured by DWS, we found that the solutions exhibited slight heterogeneity behavior at the lower concentration of 0.25%, while the material displayed a definite degree of heterogeneity at higher concentrations. DWS microrheology measurements were in excellent agreement with the conventional mechanical rheological studies for CSNC. The magnitude of the high-frequency viscoelastic moduli (|G*()|) for the CSNC was proportional to the 0.75 , which entails semi-flexible polymer behavior. The identified properties of the CSNC will provide useful information for utilizing this kind of nanocellulose in various applications.