**3. Use of additives and modifications in PVA/starch biobased formulations**

Various additives such as plasticizers (e.g., glycerol and sorbitol), cross-linkers (e.g., glutaraldehyde and epichlorohydrin), fillers (e.g., silicium dioxide and calcium carbonate), and natural raw materials (e.g., cellulose and chitosan) as well as thermoplastic starch have been used to improve the mechanical, thermal, and morphological properties of PVA/starch-based biodegradable hybrid films. Furthermore, a variety of methods including esterification, oxidation, and etherification were applied in order to modify the starch [25]. These novel additives and the modifications have been discussed under the following subheadings as plasticizers, cross-linkers, fillers, and chemical and physical modifications.
