Synthesis Of Complex Of Lanthanum(Ⅲ) With N-benzyl Maleamic Acid And PVC Thermal Stability With Test Evaluation Method Research

Polyvinyl chloride （PVC） is one of the five general plastics, whose production andconsumption in the world are less than polyethylene （PE） and lie in the second place. BecausePVC has the advantages of flame resistance, wear resisting, chemical resistance, goodelectrical insulation, strong mechanical performance, etc, it has been widely used in manyfields. But its poor thermal stability and easily dehydrochlorination of PVC with hydrogenchloride （HCl） elimination create many problems in PVC processing, including conjugateddouble bond formed. These unsaturated bonds are further oxidized, and lead to form a serialof degradation of products. In order to ensure the processing of PVC with high quality, theheat stabilizer has been added in PVC. On the one hand, the research of heat stabilizers ofPVC gets more and more attention. On the other hand, however, few works about the thermalstability and evaluation of thermal stabilizer of PVC have been reported. Based on the ideamentioned above, the following four aspects were discussed in my thesis:1.The complex of N benzyl maleamic acid radical and lanthanum （Ⅲ）（LaL₃） wassynthesized by using maleic anhydride, benzyl amine, sodium hydroxide, lanthanum oxideand hydrochloric acid as raw material. Infrared spectroscopy （IR）, melting point, elementalanalysis and thermal characterization suugest that the complex is LaL₃·H₂O, which is mytarget product.2.Effect of LaL₃on PVC thermal stability was tested by congo red test, double rollerexperiment, ultraviolet spectrum analysis, infrared spectrum analysis and thermogravimetric analysis, and compared with pure PVC. The experiments have shown that theadding of LaL₃enhances both thermal stability temperature of PVC and thermal stability time.LaL₃is suitable as PVC thermal stabilizer. 3.The thermal stability of PVC in the temperature range of150190℃was evaluated byultraviolet spectrum experiment. The experimental results indicate that conjugated polyenestructure whose conjugated double bonds number is3is mainly generated in the thermaldegradation process of PVC, at the same time, it also generates a small amount of conjugatedpolyene sequence whose conjugated double bonds number is49. With increase of thermaldegradation time, the concentration of short chain structure and long chain structure changeobviously.4.By using thermogravimetry and constant temperature thermogravimetric experiments,we can examine the effect of different heat stabilizer on PVC thermal stability under air andnitrogen atmosphere. The results show that the different heat stabilizer has obvious differentimpact on PVC thermal stability, and the constant temperature loss of weight under airatmosphere is far greater than that under nitrogen atmosphere, which suggests that thermaldegradation of PVC under the aerobic environment carrry out more thoroughly.