Effects of kappa-carrageenan on the physico-chemical properties of thermoplastic starch

Polymers obtained from renewable sources are extensively considered due to their low cost and wide range of functional properties. This research focuses on fabricating blends and composites from natural polymers specifically cassava starch and kappa-carrageenan. Blends formed by these materials offer new remarkable applications such as the fabrication of edible films. Plastics films from starch and kappa-carrageenan blends were successfully produced by the casting method. To validate their synergistic performance, the physico-chemical properties of the films were evaluated. Results showed that there is no significant change on the color of the films, L* (lightness variable). Increase in water solubility shows linear dependency on the kappa-carrageenan content. The moisture content is decreasing as the amount of kappa-carrageenan is increased. Incorporation of kappa-carrageenan (90/10 w/w starch/kappa-carrageenan blend) showed a significant change (p \u3c 0.5) to the thickness of the films. The infrared spectra showed a shift of C-O-C band from 1010.63 cm-1 (100/0 ratio) to 1002.91cm-1 (90/10 ratio), and a shift of C-H band from 2391.56 cm-1 (100/0) to 2399.27 cm-1 (90/10) suggesting physical entanglements between molecules. As the kappa-carrageenan is increased, tensile strength increased, % elongation decreased, aw increased, and pH increased. WVTR decreased significantly from 82.73 g/(m2.day) for pure thermoplastic starch to 11.31 g(m2.day) for 90/10 % (w/w) starch/kappa-carrageenan ratio, a value already comparable to polypropylene