Study of the combined effect of both clay and glycerol plasticizer on the properties of chitosan films

Chitosan-based nanocomposites at different sodium montmorillonite loadings, with and without glycerol as plasticizer, were produced by solution casting. The combined effect of glycerol and silicate clay on the thermal, mechanical and barrier properties of the obtained nanocomposites was investigated. Films containing 10% (wt/wt) of Na-MMT show, with respect to neat chitosan, reduced water permeability of about 30% and 50% and an increased tensile strength of about 120% and 25%, for films with and without glycerol, respectively. The improvement of barrier and mechanical properties was correlated both to the films nanostructure and to the interactions between chitosan, Na-MMT and glycerol. XRD results suggest that in films without glycerol, which exhibit the best barrier properties, the Na-MMT stacks lay with their platelets parallel to the casting surface. The nanocomposites obtained with addition of glycerol show the best mechanical properties due to the enhancement of chitosan intercalation in the silicate galleries.