The sodium alginate/gelatin interpenetrating polymeric network (IPN) films were prepared by incorporating gelatin crosslinked with oxidized starch as a crosslinking agent into sodium alginate crosslinked with calcium chloride as a crosslinking agent.The structures of oxidized starch and sodium alginate/gelatin IPN films were investigated by Fourier transform infrared spectroscopy (FTIR).The effects of the oxidation degree of oxidized starch on the mechanical properties

thermal stabilities

micromorphologies

crosslinking degree

and water absorption and retaining rates of IPN films were investigated in details.The results indicated that tensile strength

elongation at break and crosslinking degree of IPN films first increased and then decreased with increasing oxidation degree of oxidized starch

and the above properties of the IPN films were optimized when the oxidation degree of oxidized starch increased to 60%.However

the water absorption and retaining rates first decreased and then increased with increasing oxidation degree of oxidized starch

and the reason was that the abundant hydroxyl and carboxyl groups of both macromolecular chains

which were hydrophilic

were trapped when uniform and dense network structures were formed in the two phases with increasing oxidation degree of oxidized starch

which decreased the water absorption and retaining rates of IPN films.And the results also indicated that there existed an optimal crosslinking degree of oxidized starch for crosslinking alginate/gelatin system.