Comparing the Effect of Sodium-Based and Calcium-Based Crosslinkers on the Swelling, Mechanical and Rheological Properties of Chitosan/Gelatin/Starch Films

Abstract

In this research chitosan/gelatin/starch films with a 47.5/47.5/5.0 (vol.%) composition were prepared by a solution casting method. To improve the mechanical and rheological properties of the chitosan-based films, two types of chemical crosslinkers, sodium triphosphate (STP) and calcium triphosphate (CTP), were used and the effects of these crosslinkers on the mechanical properties, swelling, water vapor transmission rate (WVTR) and the rheological-mechanical spectroscopy (RMS) of the films were investigated. For each crosslinker, two concentrations (0.05 and 0.1 wt% solutions) were used. The tensile test results showed that the samples with 0.05 wt% of STP or 0.1 wt% of CTP, had the best performance in enhancing the tensile strength and modulus of the films. The swelling tests indicated that 0.05 wt% of STP had the lowest swelling, and the performance with 0.1 wt% of CTP was also good. The results of the WVTR tests revealed that 0.05 wt% of STP and 0.1 wt% of CTP had the least and the most WVTR, respectively. Also, antibacterial tests were evaluated for the films based on an inhibition zone technique, and the results showed that the films containing the STP crosslinker has the best antibacterial activity. The RMS results indicated that the rheological properties of the films were enhanced by incorporating the crosslinkers, especially 0.1% concentration of CTP, into the film formulations.