Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE A composite thermal stabilizer formed by mixing Glu Zn with CaSt2 and Pe is utilized for stabilizing Polyvinyl 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 Zn5(C5H7NO4)2(OH)6·H2O 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 (CaSt2) 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/CaSt2 to contrast their synergistic effects. The results showed that Pe had the best synergistic effect among the three additives.