Effects of ionic crosslinking on physical and mechanical properties of alginate mulching films

•We studied effects of different ions on alginate films with 0.011–0.014mm thickness.•We studied radiometric properties of ionic crosslinking alginate films.•Ca2+, Zn2+ and Mn2+ could improve physical and mechanical properties of alginate films.•Alginate films which were cross-linked in 2% CaCl2 for 2min had the optimal performance.•The cross-linked alginate films are well suited for application as agricultural mulching films. The effect of different ionic crosslinking parameters on the thickness, radiometric profiles, and mechanical and water vapor permeation (WVP) properties of alginate mulching films was investigated. Crosslinking by Mn2+, Zn2+, and Ca2+ (but not Al3+) increased the tensile strength and light transmission and decreased the WVP of the films. Among the films, those crosslinked by Ca2+ had the greatest tensile strength and exhibited the highest elongation and light transmission. Furthermore, the WVP and light transmission decreased gradually with increasing Ca2+ concentration, and the maximum tensile strength and elongation were obtained for 2% (w/v) of Ca2+. However, the WVP of the films increased gradually with increasing crosslinking time, and the elongation saturated after 2min. These results suggest that alginate films crosslinked by 2% (w/v) calcium chloride for 2min had the best overall performance and therefore have the potential to be used as entirely biodegradable agricultural mulching films.