Study on Application and Mechanism of Alkali Sulfadiazine Neodymium as PVC Heat Stabilizer

In this paper, the alkali sulfadiazine neodymium (NdSD) was prepared from sulfadiazine and neodymium nitrate hexahydrate under alkaline conditions, and used as a heat stabilizer on PVC. The structure of NdSD was characterized by elemental analysis and infrared spectrum. The results show that the molecular formula of NdSD is Nd (SD)₂·OH·H₂O. The thermal degradation process of NdSD at 25-800°C was characterized by thermogravimetric analysis. The results show that the decomposition temperature of NdSD is higher than 200°C, which is suitable for PVC thermal stabilizer. The thermal stabilizer time of PVC by NdSD was characterized by static Congo red method. The results showed that the thermal stabilizer time of PVC increased from 2.7min to 23.2 min after adding NdSD. The discoloration effect of NdSD on PVC was characterized by oven discoloration method. The results indicate that PVC samples added with NdSD show better effect than other heat stabilizers. By means of silver nitrate solution method and Fourier transform infrared spectroscopy, it was proved that sulfadiazine neodymium can absorb and react with HCl, and further proposed a possible mechanism of NdSD stabilization of PVC.