Acetylation degree, a key parameter modulating chitosan rheological, thermal and film-forming properties

The effect of blue crab chitosan acetylation degree (AD) on its rheological, thermal and film-forming properties was investigated. Determination of the dynamic viscoelastic properties (elastic modulus G' and viscous modulus G) of chitosan solutions revealed a typical Newtonian viscous-like behavior, with higher viscosity values at lower acetylation degrees. Moreover, the gelation temperature of blue crab chitosan was strongly dependent on its acetylation degree, with lower values at lower acetylation degrees. Regarding chitosan thermal stability, thermogravimetric profiles revealed greater thermal resistance for chitosans with lower acetylation degrees, showing significantly higher degradation temperature. Likewise, the values of glass transition temperature decreased with the increase of the acetylation degree. In another side, chitosan-based films, with lower acetylation degrees, are found to be more flexible, resistant and transparent. Therefore, blue crab chitosan acetylation degree modulated toughly its viscosity, elongation at break, tensile strength and thermal resistance. Further, chitosans with ADs less than 20% seemed to have potential industrial applications.