Synthesis of Bio-base Plasticizer Using Waste Cooking Oil and Its Performance Testing in Soft Poly(vinyl chloride) Films

Waste cooking oil was modified to prepare bio-base plasticizers (a, b and c) with terephthalic acid, adipic acid and benzoic acid by transesterification, epoxidation and ring opening reactions, respectively. The polyvinyl chloride (PVC) films (a/PVC, b/PVC and c/PVC) were prepared using a, b and c as bio-base plasticizers. The epoxidation and ring opening reactions were mainly investigated through GC-MS analysis. The structures of bio-base plasticizers (a, b and c) were confirmed by Fourier transform infrared spectroscopy (FT-IR), 1H NMR and 13C NMR. The mechanical properties of a/PVC were as good as those of PVC films with the dioctyl phthalate (DOP) plasticizer. Meanwhile, the elongation at break of c/PVC reached 422%. The glass transition temperature (Tg) from dynamic mechanical analysis (DMA) was reduced to 30.6˚C, 45.3˚C, 23.6˚C and 40.6˚C, respectively when 40 phr of a, b, c and DOP plasticizer were added. Results of thermogravimetric analysis (TGA) illustrated that the thermal degradation stabilitiy of a/PVC films was better than those of c/PVC and DOP/PVC. The volatility losses of a, b and c were lower than that of the DOP. Bio-base plasticizers a and c exhibited excellent migration resistance in different solutions (distilled water, 50% ethanol (w/w)). The FT-IR of PVC films showed that the downfield shifts of the —CH—Cl groups of the PVC plasticized with a and c were greater than that of b/PVC. The bio-base plasticizers b had a better plasticizing effect at low temperature.