Although the TOCN widths are always 3-4 nm, average lengths/length distributions of TOCNs vary depending on oxidation and disintegration conditions. Especially, length/length distribution of TOCNs has significant influence on mechanical, thermal, optical and gas-barrier properties of TOCN-films and -composites. Although measurement of TOCN lengths on TEM images provides the length information, it is quite time-consuming and needs technical skills. In this study, therefore, we developed a new evaluation method of average lengths of TOCNs prepared under various conditions, based on rheological theory of polymer solutions. Namely, 0.01-0.10% TOCN/water dispersions were subjected to steady state shear measurements using a rotary rheometer under suitable conditions. Their shear rates at the initial shear-thinning points were first measured, and then applied to an equation expressing flow properties of rod-like polymers in dilute regime. The average TOCN lengths thus calculated corresponded well to those measured on TEM images.

Determination of average lengths of TEMPO-oxidized cellulose nanofibrils (TOCNs) dispersed in water by rheological method

245th National Meeting (2013)

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