Preparation and performance of PVC long-term heat stabilizer based on the synergistic effect of uracil and metal complexes

In order to improve the deficiency of traditional polyvinyl chloride (PVC) heat stabilizer, triazole-based zinc-containing complex (abbreviated as [Zn(ttr)(OAc)]) with good compatibility with PVC and a strong ability to absorb HCl was prepared in this paper, which was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM) and thermogravimetric analysis (TGA). PVC sheets were prepared by mixing PVC with composite heat stabilizer (DAJ) composed of [Zn(ttr)(OAc)] and 1,3-dimethyl-6-aminouracil (DAU). Different kinds and amounts of common auxiliary heat stabilizers were selected and added to the DAJ system to study the effect of thermally stable system on PVC by Congo red test, Discoloration test, Dynamic thermal stability test, SEM, TGA and Transmittance test and the relevant mechanism was explored. The PVC sheets with DAJ blended by 1.2 phr DAU and 0.8 phr [Zn(ttr)(OAc)] showed relatively excellent coloring properties, long-term thermal stability, and high light transmittance. Compared with dibenzoylmethane (DBM), 0.5 phr sorbitol and 1.5 phr epoxy soybean oil (ESBO)/Antioxidant 168 showed good synergistic effect with DAJ. Due to the polyhydroxy nature of sorbitol, the thermal stability of PVC was significantly improved, and the transmittance of PVC benefited from the similar miscibility of ESBO long chain. This was also confirmed by TGA and SEM of PVC sheet.