Nanofibrillated natural cellulosic structures, or nanocelluloses, have attracted increasing attention as high-performance sustainable materials with high elastic moduli, high strength and small thermal expansions. Nanocellulose can form various types of robust structured materials such as transparent films with high strength,and low oxygen permeability. Such films are suitable for packaging or substrates for flexible electronics devices. The physical properties of nanocellulose materials are directly linked to the size (width, length and aspect ratio) of nanocelluloses.The widths of nanocelluloses can be estimated by microscopy (e.g. atomic force microscopy (AFM), scanning electron microscopy and transmission electron microscopy), solid-state <sup>13</sup>C nuclear magnetic resonance spectroscopy, and small-angle X-ray scattering. In particular, microscopy has been often used for the width measurement. However, microscopic methods are time-consuming, and there is no guarantee that the sampled images represent the whole system. Clearly we need a more robust, fast measure that can represent the ensemble. Carr and Hermans have reported that the mass-length ratio of very long and thin rigid rod-like particles such as fibrins can be simply calculated from the turbidity of the dispersion (Macromolecules, 1978, 11, 46). In the present study, we estimated the nanocellulose widths from the turbidity of their water dispersions according to the method proposed by Carr and Hermans. The nanocellulose samples were prepared by various methods, and have different widths and lengths. The widths of the nanocelluloses calculated from their turbidity values were linearly correlated with the widths measured by AFM, which was not influenced by their lengths.

Estimation of the nanocellulose width from turbidity

251st National Meeting (2016)

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