Study On The Synthesis And Application Of Rare-earth As New Thermal Stabilizer For PVC

Poly(vinyl chloride) trade is obtained to develop rapidly in recent years in China. Therefore, the thermal stabilizers for PVC become more important. It is necessary to add some thermal stabilizer to prevent or retard PVC from degradation. At present, toxic lead stabilizers are widely used. With increasing health consciousness, the lead salts stabilizers must be forbidden gradually in future, and non-toxic efficient and composite thermal stabilizers are focused on development.Rare-earth compound stabilizer is a new kind of PVC thermal stabilizer. Rare-earth compound stabilizer is fit for many PVC product because of non-toxicity, efficiency, functionality and economy etc. The rare-earth resource is abundant in China. So it is greatly significant to utilize the rare-earth resource and develop PVC thermal stabilizers which are fit our country.A new kind of rare-earth compound as PVC thermal stabilizer was synthesized in the paper, rare-earth maleic aniline acid salt. Based on experiments four kinds of rare-earth maleic aniline acid salt were synthesized, the influencing factors such as the concentration of NaOH, the concentration of RECl3, pH and reaction time were investigated. With the date of orthogonal test, the preferable synthetic conditions were found. The molecular formulas of rare-earth maleic aniline acid salt were confirmed by TG and element analysis. And the coordination mode was confirmed by FTIR, UV and H1NMR analysis. The thermal stabilities of these four rare-earth maleic aniline acid salts were researched through static and dynamic methods. Their order of stability is LaL3>DyL3>YL3>SmL3. Compared with traditional thermal stabilizers, the stability of rare-earth maleic aniline acid salts is better than rare-earth straight chain fatty acid salts and other stabilizers, and a little lower than organic tin stabilizer. The synergistic effects of the rare-earth maleic aniline acid salts with other stabilizers were also discussed. The results showed that the rare-earth maleic aniline acid salts were well synergistic with CaSt, organic tin and pentaerythritol. The mechanism of stabilization for PVC is conjectured by FTIR analysis. Because the electron shell structure of rare-earth with empty 4f, 5d and 6s orbits, it can react coordinately with labile chlorine atoms easily in PVC chains when they are in the heated process, and it can also absorb dehydrochlorination. Based on experiments rare-earth composite thermal stabilizer was prepared. And the stability and mechanics performance were promoted evidently by the rare-earth composite thermal stabilizer.