The Synthesis of a Glutamate Zinc Complex and Investigation of Its Performance as a Heat Stabilizer for Poly(Vinyl Chloride)

ABSTRACT A new organic zinc heat stabilizer could be applied to polyvinyl chloride (PVC). Glutamic acid zinc complex (Glu‐Zn) was synthesized by a simple precipitation method in one step under alkaline conditions using glutamic acid and zinc acetate dihydrate as reaction raw materials. Its chemical element composition of Zn 5 (C 5 H 7 NO 4 ) 2 (OH) 6 ·H 2 O was analyzed by elemental analysis, crucible thermogravimetric method, infrared spectroscopy, and thermogravimetric analysis. The heat stability effect of Glu‐Zn in PVC was studied using Congo red and oven aging methods. The best synergistic thermal stabilization effect was achieved when Glu‐Zn compounded with calcium stearate (CaSt 2 ) at a ratio of 0.6:2.4. Moreover, the heat stability mechanism of Glu‐Zn in PVC was researched through experiments for the absorption of hydrogen chloride and substitution of unstable chlorine, and the results showed that Glu‐Zn could substitute the active chlorine atoms in the PVC molecule to avert additional thermal degradation and also eliminate the acidic HCl generated by subsequent degradation. In addition, the commercial auxiliary heat stabilizers such as pentaerythritol (Pe), dibenzoyl methane (DBM), and epoxidized soybean oil (ESBO) were added to Glu‐Zn/CaSt 2 to contrast their synergistic effects. The results showed that Pe had the best synergistic effect among the three additives.