The Effects of Partial Deacetylation on the Ultrasonic Mechanical Treatment to Prepare Chitin Nanofibrils

Abstract

Chitin nanofibrils (ChiNF) were prepared using a partial deacetylation of the chitin-ultrasonic mechanical method. The effects of degree of deacetylation (DD) of chitin on the ultrasonic treatment conditions and structures of the ChiNF were explored via Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), wide angle X-ray diffraction (WAXD) and zeta potential analysis. The results showed that with increasing the DD of chitin, the yields of the ChiNF increased, the average lengths increased, the average diameters were unchanged and the zeta potentials gradually increased. The DD of the ChiNF, however, remained constant in comparison to that of corresponding deacetylated chitin (d-chitin) and, accordingly, the crystallinity indices increased and the grain size was reduced. The ChiNF dispersion, obtained from the optimal process, i.e. deacetylation time of 4 h and ultrasonic treatment time of 1.5 h, was cast into a transparent ChiNF film, and it exhibited enhanced mechanical properties and water-resistance after heat treatment.