Systematic dynamic viscoelasticity measurements for chitin nanofibers prepared with various concentrations, disintegration times, acidities, and crystalline structures

Dynamic viscoelasticities were measured for chitin nanofiber (ChNF) dispersions prepared with various concentrations, disintegration times, acidities, and crystalline structures. The 0.05 w/v% dispersions of pH neutral ChNFs continuously exhibited elastic behavior. The 0.05 w/v% dispersions of acidified ChNFs, on the other hand, transitioned from a colloidal dispersion to a critical gel and then exhibited elastic behavior with increasing ChNF concentration. A double-logarithmic chart of the concentration vs. the storage modulus was prepared and indicated the fractal dimension and the nanostructure in the dispersion. The results determined that the neutral alpha- and beta-ChNFs were dispersed but showed some remaining aggregations and that the acidified beta-ChNFs were completely individualized. In addition, the alpha-chitin steadily disintegrated with increasing disintegration time, and the aspect ratio of the beta-chitin decreased as a result of the exscessive disintegration. The storage moduli of the ChNFs were greater than those of chitin solutions, nanorods, and nanowhiskers with the same solids concentrations. (C) 2018 Elsevier B.V. All rights reserved.