Study On The Preparation And Thermal Stability Of Rare Earth Nitrogen-Containing Heterocyclic Organic Stabilizer

In this thesis,the effect of rare-earth heat stabilizers with different groups on stability performance was first studied.Using 6-carboxyuracil and 6-methyluracil?MUA?as ligands,two rare earth stabilizers,6-carboxycarboxyuracil lanthanum?LMUA?and6-methyluracil lanthanum,were synthesized with lanthanum nitrate and ammonia.By infrared spectroscopy,thermal analysis and elemental analysis,the rare earth heat stabilizer synthesized was characterized to determine its molecular formula.Through the experiment of Congo red and thermal aging box,the thermal stability of rare earth heat stabilizer was compared.The results showed that the thermal stability of lanthanum 6-methyluracil was much better than that of lanthanum 6-carboxyuracil.Then the synthesis of different rare earth element stabilizers and their influence on thermal stability were studied.Using 6-methyluracil,lanthanum nitrate,cerium nitrate and ammonia-water as raw materials,6-methyluracil cerium?CMUA?and 6-methyluracil cerium lanthanum?CLMUA?were synthesized.The synthetic stabilizers were characterized by infrared spectrum and thermal analysis.The static thermal stability of rare earth thermal stabilizers was studied using Congo red and high temperature thermal aging experiments;the dynamic thermal stability of rare earth thermal stabilizers was studied using electrical conductivity method.In the static and dynamic thermal stability experiments,the rare earth thermal stabilizers were compounded binary and ternary with zinc stearate,calcium stearate and pentaerythritol,respectively.The results of static thermal stability experiments show that the thermal stability performance of the rare earth thermal stabilizer alone is:LMUA>CLMUA>CMUA,and the thermal stability effect of ternary compounding is better than binary compounding.The results of dynamic thermal stability experiments show that the thermal stabilization sequence of thermal stabilizers is:single rare earth heat stabilizer>binary compounding>ternary compounding,and the thermal stability order of single rare earth heat stabilizer is the same as static.It was finally found that LMUA is the best main stabilizer?Ts=142 min?.But It was also found that CLMUA is the best main stabilizer when both performance and cost are considered.At the same time,ultraviolet spectrum absorption experiment and torque rheology experiment were carried out,and the light stability performance and processing performance of rare earth stabilizer were preliminary studied and compared.Finally,the mechanism of the effect of rare earth stabilizers was studied.The rare earth heat stabilizer can not only reduce the bond of C-Cl in PVC,but also absorb PVC to decompose HCl generating RECl₃,which weakened the further catalytic degradation of HCl and achieved the effect of thermal stability.After removing rare earth ions,6-Methyluracil rare earth stabilizer combined with hydrogen ions released from polyvinyl chloride to produce 6-methyluracil and dilute nitric acid.