Eco-friendly plasticizer production from waste cooking oil using nanomaterial and its application in polyvinyl chloride films

The improper disposal of waste cooking oil (WCO) poses a significant environmental challenge, despite its potential as a renewable feedstock for value-added products. In this study, WCO was chemically converted into an eco-friendly plasticizer for polyvinyl chloride (PVC) through an epoxidation process catalyzed by nano-graphene oxide synthesized from citric acid. The successful epoxidation was confirmed by the appearance of characteristic epoxy absorption bands at 820–880 cm −1 in the FTIR spectra, as well as by improved thermal stability and glass transition behavior compared to raw WCO. The epoxidized WCO-based plasticizer was incorporated into PVC formulations and benchmarked against conventional di-octyl phthalate (DOP). Thermal and structural properties of the resulting films were evaluated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The optimized formulations (P1 and P4) demonstrated enhanced thermal stability, reduced crystallinity, improved miscibility, and better color retention under thermal aging. Furthermore, preliminary migration and solvent resistance tests indicated favorable durability of the plasticized films. These results confirm that nano-graphene-oxide-assisted epoxidized WCO is a promising sustainable alternative to traditional phthalate plasticizers.