Effects of ionic crosslinking on physical and mechanical properties of alginate 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 Mn(2+), Zn(2+), and Ca(2+) (but not Al(3+)) increased the tensile strength and light transmission and decreased the WVP of the films. Among the films, those crosslinked by Ca(2+) had the greatest tensile strength and exhibited the highest elongation and light transmission. Furthermore, the WVP and light transmission decreased gradually with increasing Ca(2+) concentration, and the maximum tensile strength and elongation were obtained for 2% (w/v) of Ca(2+). However, the WVP of the films increased gradually with increasing crosslinking time, and the elongation saturated after 2 min. These results suggest that alginate films crosslinked by 2% (w/v) calcium chloride for 2 min had the best overall performance and therefore have the potential to be used as entirely biodegradable agricultural mulching films.