Study and comparison of the heat stability of PVC stabilized by rare earth stearate and by calcium stearate

In order to deepen understanding rare earth heat stabilizers, the heat stability of rare earth stearates on PVC was compared and studied and their stabilizing mechanisms are discussed by using calcium stearate as the reference and lathanum stearate as the representative.The results showed that:(1)the heat stability of rare earth stearates was similar to that of calcium stearate;(2) LaSt3/ZnSt2 were similar to CaSt2/ZnSt2 in the combination effects with epoxidized soybean oil,and slightly poorer than CaSt2/ZnSt2 in the combination effects with pentaerythritol(PET) and dibenzoyl methane(DBM);(3)the reason why poorer combination effects with PET and DBM of LaSt3/ZnSt2 than that of CaSt2/ZnSt2 was that La3+ was so more forceful than Ca2+ to compete with Zn2+ to form composite with PET and DBM that the roles of PET and DBM couldn't fully play.