Preparation and characterization of glycerol plasticized (high-amylose) starch–chitosan films

The chitosan–starch (high amylose) blend film (1;1), via microfluidization, was prepared by casting with different glycerol concentration (0%, 2.5%, 5% and 10%). The films were characterized for their mechanical, thermal and morphological properties. The addition of glycerol at 5% (w/w) and higher concentrations resulted in decrease in tensile strength, increase in elongation at break due to plasticization. The well-known antiplasticization was observed in the polymer films with 2.5% of glycerol. The addition of glycerol promoted the interactions among chitosan, starch and glycerol through hydrogen bonding as reflected on the shifting of main peaks of the glycerol-free film to higher wavenumbers as shown by FTIR spectra. The decrease in intensity of glycerol-related peaks in starch–chitosan–glycerol films in both 1H NMR and 13C NMR spectra proved the strong interactions (decrease in glycerol mobility) occurring among starch, chitosan and glycerol in glycerol-plasticized films.

► Film casting solutions were homogenized using microfluidization.
► Glycerol c% > 5% was adequate to produce starch + glycerol + chitosan films.
► Antiplasticization (film cracking and high Tg) was observed in <2.5% glycerol.
► Glycerol formed hydrogen bonds with starch/chitosan proven in FTIR spectra.
► Three-way interactions occurred as shown in FTIR and NMR spectra.