The processability and properties of agar/gelatin film in a melt-mixing process

The rising concern in the use of nonbiodegradable plastics has triggered the search for potential substitutes from renewable sources. Agar and gelatin are two potential sources of bio-based plastic; however, their preparation process mostly uses solution casting, which uses toxic substances, limiting its processability in industrial machinery. In this study, agar/gelatin film was produced through a twin-roll mixer without any involvement of any toxic chemicals, creating a greener process of bioplastic. The resulting films were investigated in terms of processability, chemical structure, thermal properties, tensile properties, contact angle, and biodegradation. The loading of gelatin improved the processability of the agar film blends, which is comparable with synthetic plastic, such as high-density polyethylene and polypropylene. With the gelatin loading of 3 wt.%, the tensile strength increased from 20.80 to 25.89 MPa. The presence of gelatin enhanced the onset degradation temperature (Tdonset) and peak degradation temperature (Tdpeak) of glycerol while lowering both values in agar. Contact angle increased from 38.17° to 67.77° with the presence of 4 wt.% gelatin. These results show that agar/gelatin has a promising future to be an environmentally friendly substitution for synthetic, nondegradable plastic and can be produced in a common plastic industry equipment.