Evaluating the state of dispersion on cellulosic biopolymer by rheology

The key challenge in the development of cellulose bio-nanocomposites lies in the spatial distribution of the cellulose fibre, as the presence of surface hydroxyl groups initiates self-agglomeration, thereby resulting in crack or failure of the composites. In this study, nanocrystalline cellulose (NCC) is here effectively surface acetylated to reduce agglomeration. Poly(lactic acid) PLA based cellulose bio-nanocomposites were then prepared by solvent casting technique. A rheological percolation threshold is calculated to quantify the level of dispersion and the optimal loading. Moreover, high frequency linear viscoelastic behavior is analyzed and the data is fitted to the Krieger-Dougherty equation to determine the maximum packing fraction. Maximum packing fraction value is then used as a mean to rank the quality of dispersion. The value for maximum packing fraction is compared with microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC), to show how shape and structure affects the quality of dispersion. (C) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43200.