Study On The Synthesis Aannddapplication Of Complex Of Lanthanum (â…¢) With N-linear Alkyl Maleamic Acid And The Thermal Stability For PVC

With low cost, high strength, plasticizing, corrosion resistance, flame retardant, goodinsulation and high transparency, etc. PVC is used in every field of national life. But itsthermal stability is poor, thermal degradation happens when processing under the condition of160²20℃. Therefore, we have to add the appropriate heat stabilizer in the processing ofPVC to avoid its degradation.The rare earth stabilizer is one of the special non-toxic stabilizer systems which have theadvantages of non-toxic, high efficiency,multifunctional. In addition, our country is abundantin rare earth. The rapid development of rare earth stabilizers has practical significance andeconomic significance in building with Chinese characteristics of new PVC heat stabilizersystem.In this paper, we adopt the direct method to synthesize six complex of lanthanum （Ⅲ）with N-linear alkyl maleamic acid and use them as the heat stabilizer for PVC. Theexperiments show that, the main Influencing factors are the grinding time, grindingtemperature, baking time and baking temperature. During the synthesis of complexes, theinfluencing factors such as the CLa（NO3）3、CNaOH、nOH-：nHLand reaction time. We analyze avariety of factors and levels by orthogonal experimental method and finally determined theoptimum synthesis conditions. By means of elemental analysis, thermo gravimetric analysis（TGA）, IR spectra analysis and nuclear magnetic resonance hydrogen spectrum analysis, etc.We can speculate the formula and coordination mode of coordination compounds. Throughthe static method and dynamic method to screen the objective coordination compound. At thesame time, studying on the thermal stability of PVC among five kinds of synthetic products.The results show the growth of the carbon chain, coordination compounds’ effect on thermal stability of PVC is enhanced. And complex of lanthanum （Ⅲ） with N-hexadecyl maleamicacid has a best effect on thermal stability.Compared with the traditional non-toxic stabilizers,it has a better thermal stability than calcium stearate、zinc stearate and pentaerythritol, slightlyworse than organic tin. Compound with several other non-toxic heat stabilizers, which findthat complex of lanthanum （Ⅲ） with N-hexadecyl maleamic acid, has a good synergisticeffect with calcium stearate, pentaerythritol and organic tin. According to the synergisticeffect,having prepared composite heat stabilizer. After testing the compound heat stabilizernot only has excellent thermal stability, but also can enhance the mechanical properties ofPVC products.Through infrared spectrum and color change of PVC in the heating process, we speculatethe thermal stability mechanism of complex of lanthanum （Ⅲ） with N-hexadecyl maleamicacid to PVC is: coordination effect is easily occurring between La³⁺and active Cl in PVC,thus weaken the polarity of C-Cl bond and acidity of β-H, and so block the formation ofconjugated polyene. Moreover, due to the special electronic shell structure of La³⁺, it canproduce coordination compound through reaction to HCl which from the release of PVC andreduce the catalysis of HCl to rearrangement reaction. The organic part of the coordinationcompound can occur Diels-Alder addition reaction with conjugated polyene from thedegradation of PVC. This reaction can eliminate conjugated chains in PVC molecules andenhance the flexibility of PVC molecular chain. Therefore, it perfect the color of the PVCmaterial and the transparency of product. And it also has a good synergy with other traditionalnon-toxic stabilizers.