Sodium alginate film: the effect of crosslinker on physical and mechanical properties

In this work, the effect of calcium chloride (CaCl2) at different concentrations and immersion duration on physical and mechanical properties of sodium alginate (SA) films was examined. The results show that the swelling properties of SA films were decreased upon immersed in longer duration of CaCl2 due to improved crosslink between carboxyl group (-COOH) of SA to calcium ion (Ca2+) of the CaCl2. In contrast, gel fractions of the films were increased at longer duration of immersions. The mechanical performances of the SA film immersed in 0.8 M of CaCl2 for 8 minutes exhibited highest tensile stress, tensile strain and Young's modulus at 3.92 ± 0.3 MPa, 21.08 ± 1.3% and 27.81 ± 7 MPa, respectively compared to SA films. The results show that the optimization of crosslinker could improve the physical and mechanical performances of the SA films.