Preparation and characterization of Chitosan/talc nanocomposite films for food packaging applications

Abstract

In the present study, the effect of ultrasonication treatment time on talc particles’ morphology, crystallite size, dimensions, structure and specific surface area was investigated. Additionally, the effect of talc as a filler material in chitosan/talc nanocomposite films’ barrier, mechanical and moisture absorption properties was studied, as a function of talc crystal size and concentration. It was found that treating talc particles through ultrasonication is effective to reduce their average crystallite size, as well as decrease both the lateral dimension and the thickness of the talc platelets (delamination), while maintaining its structural coherence and crystallinity. The ultrasonication treatment was also successful in increasing the specific surface area and it was determined that the flaky, platelet like morphology of talc was preserved throughout all treatment times. Upon addition of talc to the chitosan film, up to 16% and 24% increase in Modulus of elasticity (stiffness) was found, for the larger and smaller talc crystal size, respectively. A small increase in the Ultimate Tensile Strength of the films was observed for the 5% loading in both set of films, with values of 92-94 MPa. The water vapor permeability of the films was determined to slightly decrease (4-5%) with the addition of smaller crystal size talc, at 3 and 5% loadings. The water sensitivity of the films was improved, independent of talc crystal size and for all concentrations, as it was observed that the moisture absorption percent notably decreased (18-24% maximum reduction). Chitosan-talc nanocomposites show some promise as an emerging food packaging bioplastic due to its strength, stiffness and decreased water sensitivity. However, additional work is needed on the film synthesis method to improve its barrier properties and potentially compete with traditional food packaging plastics.