Synthesis and Study of Zinc Orotate and Its Synergistic Effect with Commercial Stabilizers for Stabilizing Poly(Vinyl Chloride).

Feng Ye,Yeqian Ge,Xu Wang,Haihua Zhan,Qiufeng Ye,Xiaotao Ma

doi:10.3390/polym11020194

Abstract

Zinc orotate (ZnOr2), which is a new kind of poly(vinyl chloride) (PVC) stabilizer, is prepared in this work through the precipitation method, and its impact on the thermal stability of PVC is measured by thermogravimetric analysis (TG), Congo red test, and discoloration test. The results exhibit that the thermal stability of PVC is positively enhanced after the addition of ZnOr2. In contrast with a commercial thermal stabilizer, zinc stearate (ZnSt2), a noteworthy improvement was observed that ZnOr2 could postpone the “zinc burning” of PVC. This is principally ascribed to the Or anion in the structure of ZnOr2 being able to absorb the HCl released by PVC, and to supersede unstable chlorine atoms in the structure of PVC. In addition, blending ZnOr2 with calcium stearate (CaSt2) in diverse mass ratios can significantly accelerate the thermal stability of PVC. Optimum performance was achieved with a CaSt2:ZnOr2 ratio of 1.8:1.2. Moreover, an outstanding synergistic effect can be observed when CaSt2/ZnOr2 is coupled with other commercial auxiliary stabilizers. The initial color and long-term stability of PVC including CaSt2/ZnOr2 is significantly increased when pentaerythritol (PER) is added, while dibenzoylmethane (DBM) can only improve its long-term thermal stability.

Highlights

Poly(vinyl chloride) (PVC) is a kind of thermoplastic polymer manufactured by the polymerization of vinyl chloride monomer
Over the past few decades, various compounds have been studied as PVC stabilizers, such as metal soaps [7], lead salts [8], and organotin [9,10,11]
Lead salts and organotin have been shown to be highly effective in stabilizing PVC, the properties of high toxicity for lead salts and high price for Polymers 2019, 11, 194; doi:10.3390/polym11020194

Summary

Introduction

Poly(vinyl chloride) (PVC) is a kind of thermoplastic polymer manufactured by the polymerization of vinyl chloride monomer. It has extensive applications in the living and industrial fields because of its advantages for mature production technology, easy to process molding, corrosion resistance, abrasion resistance, flame retardant properties, and good electrical insulating performance [1,2,3]. The HCl will further catalyze the degradation of PVC, resulting in the product gradually converting from white to completely black [4,5,6]. Lead salts and organotin have been shown to be highly effective in stabilizing PVC, the properties of high toxicity for lead salts and high price for Polymers 2019, 11, 194; doi:10.3390/polym11020194 www.mdpi.com/journal/polymers

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