The effect of nanocellulose on mechanical and physical properties of chitosan-based biocomposites

The effect of two types of nanocellulose on the mechanical properties of chitosan (CH) film was examined in terms of elongation, tensile strength, and dynamic-mechanical properties such as tan δ and storage modulus. Chitosan films were reinforced by cellulose nanocrystal (CNC) and cellulose nanofiber (CNF) with different ratios. CH/CNC and CH/CNF nanocomposite films containing 0–7 wt.% nanofibers were produced by solution casting. A comparison between CNC and CNF was made based on their nanostructures and interfacial bonding with the CH matrix. For both CNC and CNF, reinforcing effects in nanocomposite polymer films were presented. The results demonstrated that nanocomposite films can increase mechanical properties; 7 wt.% CNF and CNC had the most increasing effect on the mechanical properties, raising the tensile strength of the chitosan film by 104% and 52%, respectively. Moreover, the values of CH/CNC and CH/CNF films showed higher storage modulus compared to the pure chitosan film. CNF shows higher modulus and strength compared with CNC at the same amount of fiber because of CNFs’ percolation networks and their larger aspect ratio. Morphological studies revealed the dispersion of CNC and CNF is in the contiguous matrix of chitosan with a homogeneous distribution without agglomeration. The results also illustrated that CNC and CNF can improve the water resistance of chitosan films. The mechanical properties of composite films were acceptable to use as artificial skin and wound dressings.