Utilization of waste cooking oil as a substitute for plasticizers in the production of carrageenan/cornstarch bioplastic

In the current investigation, to develop a carrageenan/cornstarch bioplastic production technique suitable for commercial-scale production, an alternative method to the commonly used solvent-casting technique was implemented through a hot-melt extrusion process. Moreover, to enhance the water resistance of the bioplastic and reduce production costs, waste cooking oil (WCO) was used as a substitute for glycerol plasticizer. Various weight ratios of WCO to glycerol (w/w) were used in formulations. All the material ingredients were compounded using a double-screw extruder at 115°C. Subsequently, the resulting extrudate was then cut into resin pellets, followed by hot compression to produce bioplastic film samples. The film samples underwent testing for mechanical properties, water resistance, biodegradability, chemical structure and morphology. The overall results showed that the addition of WCO improved the tensile properties and water resistance and accelerated biodegradation. These findings were attributed to the presence of ester groups in the polymer structure, the intrinsic hydrophobic nature of WCO and the formation of voids within the film structure, as revealed by Fourier transform infrared spectroscopy and scanning electron microscopy analyses. Based on the findings, the utilization of WCO in carrageenan/cornstarch-based bioplastic production offers potential advantages for commercial applications.