Study on Lanthanum Cerium 6-Methyluracil As Heat Stabilizer of Polyvinyl Chloride

Abstract

Rare earth thermal stabilizers are a kind of newly discovered stabilizers, which are considered as a series of very promising stabilizers for inhibiting the degradation of PVC in the application and processing. Therefore, the continued exploration of new rare earth heat stabilizer is very necessary for scientific research and practical application. In this work, a new rare earth thermal stabilizer lanthanum cerium 6-methyluracil (LCMUA) was successfully synthesized via using cerium nitrate, lanthanum nitrate, 6-methyluracil (MUA) and aqueous ammonia as raw materials. And it was characterized by elemental analysis, FTIR, TG and other methods, the molecular formula of lanthanum cerium 6-methyluracil is confirmed as: La_0.35Ce_0.65(C₅H₄N₂O₂)NO₃⋅2H₂O. Subsequently, congo red tests and thermal aging tests of pristine LCMUA and LCMUA with calcium stearate (CaSt₂), zinc stearate (ZnSt₂), and pentaerythritol (PE) composite samples were performed, when LCMUA/CaSt₂/PE is compounded with mass ratio of 3 : 1 : 1, the heat stabilization time reached 70 min, and the heat stabilization performance was the best, which is better compared to those of commercial CaSt₂ and ZnSt₂. The excellent experimental results can be attributed to the special absorption effect of LCMUA for hydrogen chloride gas derived from the thermal decomposition of PVC, thereby removing in time hydrogen chloride gas to restrain the PVC self-decomposition process caused by HCl gas.