Effects of processing on the properties of chitosan/cellulose nanocrystal films.

Biocomposites of chitosan (CS)/cellulose nanocrystals (CN) were prepared by using solution casting method. Influences of solution preparation method and CN content on the properties of composites were investigated. Mechanical stirring/ultrasonication or microfluidization were used to disperse nanocrystals in the chitosan matrix. The prepared nanocomposites were characterized by FTIR, XRD, SEM, DSC, TGA, TMA and contact angle measurements. SEM analysis revealed that microfluidization decreased CN aggregates in matrix. Formation of hydrogen bonds between CS and CN in nanocomposites prepared by using microfluidization was confirmed by FTIR spectroscopy. This high interaction led to an increment of the crystallinity of chitosan films. Tg values within a range of 53-58°C were obtained in DSC and TMA measurements. The thermal stability of CS film showed no significant effect of CN addition, whereas contact angle measurements revealed that CN addition resulted in an increment of hydrophilicity of chitosan films.