The effects of glycerol, sorbitol and oleic acid On mechanical properties, water vapor and oxygen Permeability's for methylcellulose composite thin films

Cellulose derivatives have very good film-forming properties but their main problem is their poor resistance to water vapor. The effect of individual substances of glycerol, sorbitol and oleic acid and their combined effects on mechanical properties, water vapor and oxygen permeabilities of methylcellulose composite thin films have been studied. Results demonstrated that the above substances yielded in significant changes (P<0.05) on mechanical properties, water vapor and oxygen permeabilities. Oleic acid not only had a plasticizer role but also resulted in reduction in water vapor transmission rate (WVTR) and water vapor permeability (WVP). The reduction rates of WVTR and WVP for the film containing sorbitol were smaller than that of the film containing glycerol. The values of WVP for the composite films [(77% methylcellulose- 7.7% glycerol- 15.4 Oleic acid) and (77% methylcellulose-7.7 % sorbitol- 15.4% oleic acid)] decreased 38.7% and 23.72% in comparison with the films (91% methylcelluose–9%) and (91% methylcelluose – 9% sorbitol), respectively. Similar changes in mechanical properties and oxygen permeability were observed using the above substances in the methylcellulose composite films.