An efficient bio-based plasticizer for poly (vinyl chloride) from waste cooking oil and citric acid: Synthesis and evaluation in PVC films

Abstract

Abstract In this study, a bio-based efficient plasticizer (acetylated-fatty acid methyl ester-citric acid ester, AC-FAME-CAE) for poly(vinyl chloride) (PVC) was synthesized by using waste cooking oil and citric acid as raw materials in very user-friendly approaches. Its structure was characterized by FTIR and 1H NMR. The epoxidation and ring opening reaction were investigated primarily using a GC-MS analysis. Tetrabutylammonium chloride (TBAC) was used as the catalyst of ring opening, and it dramatically accelerated the reaction process of carboxylic acid and epoxy bonds. The glass transition temperature (Tg) decreased to 26.32 °C, as determined by dynamic mechanical analysis (DMA), when 50 phr of AC-FAME-CAE was added. The mechanical and migration stabilities of PVC films with AC-FAME-CAE plasticizer were investigated using volatility and extraction tests as well as thermogravimetric analysis (TGA) and TGA–FTIR analysis. The mechanical properties of PVC films with AC-FAME-CAE plasticizer were obviously better than those of PVC films plasticized by ESO (epoxidized soybean oil) and as good as those of PVC films plasticized by DOP (dioctyl phthalate, 99%). The structure−property analysis of the AC-FAME-CAE as a PVC plasticizer confirmed that a higher molecular weight and more ester bonds could reduce the volatility and extraction loss and improve the compatibility and stability of PVC films.