Pentaerythritol stearate ester-based tin (II) metal alkoxides: A tri-functional organotin as poly (vinyl chloride) thermal stabilizers

Abstract In this work, a non-volatile solid organotin thermal stabilizer, pentaerythritol stearate ester-based tin (II) metal alkoxides (PSE-Sn) was synthesized with a very simple process and its impact on the thermal stability and processing performance of PVC was evaluated by conductivity measurement, thermal aging, thermogravimetric analysis, and torque rheometer test. The results showed that the addition of PSE-Sn not only could significantly enhance the thermal stability of PVC, accelerate plasticization, but also improve lubrication performance during PVC processing. Thus, PSE-Sn played the role of tri-functional additives: thermal stabilizer, plasticizer, and lubricant. The joint effects of PSE-Sn with ZnSt2 and CaSt2 on the thermal stability of PVC were also evaluated. Results indicate that there is a good synergistic effect between PSE-Sn and ZnSt2 on the initial color and long-term thermal stability of PVC. However, such synergistic effect was not observed between PSE-Sn and CaSt2. In addition, the working mechanism of PVC stabilization by PSE-Sn was also explored. Furthermore, the thermal stability and processing performance of PSE-Sn and methyl tin mercaptide (MTM) on PVC were comparatively tested. PVC stabilized by MTM possessed the longest color stability. The addition of PSE-Sn could also improve the initial color stability and long-term thermal stability of PVC significantly. The results of tensile test showed that both PSE-Sn and MTM could reduce the average tensile strength of PVC but increase the average elongation at break of PVC.