Stability, mechanism and unique “zinc burning” inhibition synergistic effect of zinc dehydroacetate as thermal stabilizer for poly(vinyl chloride)

A novel kind of poly(vinyl chloride) (PVC) thermal stabilizer , zinc dehydroacetate (ZnL 2 ), was designed and synthesized using zinc acetate and dehydroacetic acid (DA) as raw materials, which had a unique "zinc burning" inhibition synergistic effect with calcium stearate (CaSt 2 ) that was 8 times greater than that of the CaSt 2 /ZnSt 2 combination reference stabilizer . The structure and stability of ZnL 2 were confirmed by Fourier-transform infrared, elemental analysis , and thermogravimetric analysis . The stability distinction of ZnL 2 and ZnSt 2 , and the stable effect of the two systems after being combined with CaSt 2 , were investigated by the Congo red test, solution acidity test, and discoloration test. The results showed that in the Congo red test the stability time of ZnL 2 was 8.9 min, which was 1.3 times that of ZnSt 2 , and the stability time of ZnL 2 /CaSt 2 was 13 min, which was 1.4 times that of a traditional Ca/Zn stabilizer. Furthermore, the stability time of ZnL 2 was 36 min in the solution acidity test, which was 2 times higher than that of ZnSt 2 , and the stability time was increased to 196 min after combining it with CaSt 2 , which was 8 times greater than that of the Ca/Zn stabilizer. Moreover, the dehydrochlorination rate of PVC stabilized with ZnL 2 was slower than with other stabilizers. The system with ZnL 2 /CaSt 2 could effectively delay “zinc burning” because of the excellent synergistic effect in the thermal aging test, with a stability time as long as 140 min. At the same time, the mechanism of PVC stabilization by ZnL 2 was studied in two simple experiments, and the stabilization mechanism of ZnL 2 in PVC degradation was speculated on.