Effect and enhancement mechanism of sodium lignosulfonate on the chitosan-based composite film

Chitosan is a desirable alternative for petroleum-derived packaging materials, but the unsatisfactory performance of most chitosan composites drastically impedes their practical application. In this work, a facile physical blending strategy was selected to prepare chitosan-based composite films with good properties utilizing sodium lignosulfonate as a reinforcing agent. The effects of sodium lignosulfonate addition on the barrier performance, antioxidant activity, UV-blocking, and mechanical properties of the composite films were evaluated. The enhancement mechanism of sodium lignosulfonate on the structural and functional properties of the membranes was also investigated. The results show that chitosan mixed with sodium lignosulfonate exhibited a higher tensile strength (~75Mpa), improved barrier property (OTR and WVTR are 4.8 g·m-2·d-1 and 415 g·m-2·d-1, respectively), increased free radical scavenging activity (29.9%), and enhanced UV-blocking ability (95%) compared to pure chitosan film. Strong electrostatic interaction and hydrogen bonding between monodispersed sodium lignosulfonate and chitosan have an essential effect on the performance of composite films. The application of sodium lignosulfonate as a reinforcing material is both environmentally friendly and economically viable, showing promising potential for use in food packaging applications.