Application of gaussian calculations in PVC thermal stabilizers: Mechanistic insights from binding energy and electron distribution value

A method for predicting the thermal stability effect from the structure of thermal stabilizers could greatly accelerate the research of efficient thermal stabilizers and achieve the high performance of the PVC products. In this work, the Gaussian software was used to establish the method by calculating the binding energy and the electron distribution value (NPA charge) of the thermal stabilizers. Three initial-type [Zn(Bzo) 2 , Zn(PTBBA) 2 , and Zn(PNBA) 2 ] and three long-term [Zn(Pro) 2 , Zn(Ple) 2 , and ZCR] organic zinc thermal stabilizers were used to establish quantitative relationships between the binding energy and the NPA charge with the thermal stability properties of PVC samples. The binding energy of anion and cation could effectively explain the ability of the thermal stabilizers to replace the labile chlorine atoms on the PVC chains and the initial whiteness of PVC samples. Zn(PNBA) 2 with a Zn-O binding energy of 0.134 ha had an initial whiteness retention time of 40 min and a Congo red thermal stability time of 17.2 min on PVC. Moreover, the NPA charge of nitrogen atom could demonstrate the ability of thermal stabilizers to absorb HCl. The higher the NPA charge, the better the ability of absorbing HCl. The NPA charge of nitrogen atom in ZCR reached -1.43 e, resulting in the Congo red thermal stability time of 56.9 min and the long-term thermal stability time of 180 min. Thus, the initial whiteness retention time, long-term thermal stability time, and Congo red thermal stability time of the thermal stabilizers could be quantitatively predicted by combining the binding energy and the NPA charge of nitrogen atom. Moreover, the relationship was verified by the replacement test and absorbing HCl experiment.