Studies On Synthesis Of Novel Rare Earth Thermal Stabilizer And Applied Research In PVC

Rare earth compound stabilizer is fit for many PVC products because of non-toxicity, efficiency,functionality, and so on. The rare-earth resource is abundant and cheap in China. So it is greatly significantto utilize the rare-earth stabilizers which replace lead salts and partly replace expensive organic tinstabilizers would be the main direction of stabilizer industry in our country in the future.Lanthanum ricinoleate and lanthanum protocatechuate were synthesized as heat stabilizers for PVC inthis thesis. The IR spectral analysis were used to defined the composition of products. The influencingfactors such as the temperature of reaction, the concentration of NaOH and reaction time on the propertiesof lanthanum ricinoleate were investigated in the paper. When the temperature is70oC, the concentrationof NaOH is8g/L and the reaction time is1h, the yield of products is about94.6%.The investigations of thermal stability are taken to the rare-earth thermal stabilizers in this thesis.Compared with lead salt and organotin218, the thermal stabilities of lanthanum ricinoleate and lanthanumprotocatechuate were researched through static method. Their order of stability is lead salt>lanthanumricinoleate>lanthanum protocatechuate>organotin218. The synergistic effects of lanthanum ricinoleate andlanthanum protocatechuate with other stabilizers were also discussed. Lanthanum ricinoleate was wellsynergistic with pentaerythritol, Ca/Zn stabilizers and organic tin. Lanthanum ricinoleate were wellsynergistic with pentaerythritol. The mechanism of stabilization for PVC is conjectured by HCl scavengerexperimentation and FTIR analysis. The result suggested that HCl can be absorbed and neutralized bylanthanum ricinoleate to restrain its catalysis, and it also may react coordinately with labile chlorine atomseasily in PVC chains. Compared with lead salt and organotin218, it is believed that rare-earth compositethermal stabilizer has a marked effect to improve elongation and impact strength of PVC. UsingPlasticorder, effects of rare-earth composite thermal stabilizer on rheological properties of PVC werediscussed and analyzed. Lead salt as reference stabilizer are also given for the purpose of comparison. Theresults show that rare-earth composite thermal stabilizer can improve plasticization of PVC and has betterprocessing properties.