PVC具有价格低廉、强度高、可增塑、耐腐蚀、难燃、绝缘和透明等优点，被广泛用于生产、生活的各个领域。但是其热稳定性差，在160~220℃条件下加工时会发生剧烈的热降解。因此，PVC在加工时必须添加适当的热稳定剂以抑制其降解。 　　　稀土稳定剂是无毒稳定剂体系中特殊的一种，具有无毒、高效、多功能等优点，我国是稀土资源大国，发展稀土稳定剂，构建具有中国特色的新型PVC热稳定剂体系具有重要的现实意义和经济意义。 本文采用直接法合成了六种N-直链烷基马来酰胺酸根合镧（III）配合物。并将其用作PVC热稳定剂。实验表明，采用固相法合成配体时，影响因素主要是研磨时间、研磨温度、烘焙时间和烘焙温度，配合物的合成过程中主要影响因素是CLa(NO3)3、CNaOH、nOH-：nHL 以及反应时间，通过正交实验，确定了最佳合成条件。元素分析、热重、红外光谱和核磁共振氢谱等分析推测配合物的分子式和配位方式。静态法和动态法结合，分别研究了五种合成产品对PVC的热稳定作用时间。结果发现：随着碳链的增长，配合物对PVC的热稳定效果增强，其中N-十六烷基马来酰胺酸根合镧（III）对PVC的热稳定效果最好，与传统无毒热稳定剂相比，其热稳定效果优于硬脂酸钙、硬脂酸锌和季戊四醇，略差于有机锡。与其他几种无毒热稳定剂进行复配使用发现，N-十六烷基马来酰胺酸根合镧（III）与硬脂酸钙、有机锡和季戊四醇具有良好的协同作用。据此制备了复合热稳定剂，经测试该复合热稳定剂不仅具有优良的热稳定性能，而且能够增强PVC产品的力学性能。通过红外光谱和受热过程中PVC颜色变化的情况，推测出N-十六烷基马来酰胺酸根合镧（III）对PVC的热稳定作用机理为：La3+容易与PVC中活跃的Cl发生配位作用，减弱了C-Cl键的极性和β-H的酸性，从而阻碍了共轭多烯的形成；另外由于La3+特殊的电子层结构，会与PVC分解释放的HCl发生反应生成配合物，减少了HCl对重排反应的催化。配合物的有机部分能与PVC降解产生的共轭多烯发生Diels-Alder加成反应，消除PVC分子中的共轭链，提高PVC分子链的柔顺性，同时改善PVC材料的颜色，提高制品的透明性

With low cost, high strength, plasticizing, corrosion resistance, flame retardant, good insulation and high transparency, etc. PVC is used in every field of national life. But its thermal stability is poor, thermal degradation happens when processing under the condition of 160 ~ 220℃. Therefore, we have to add the appropriate heat stabilizer in the processing of PVC to avoid its degradation. 　　　The rare earth stabilizer is one of the special non-toxic stabilizer systems which have the advantages of non-toxic, high efficiency, multifunctional. In addition, our country is abundant in rare earth. The rapid development of rare earth stabilizers has practical significance and economic significance in building with Chinese characteristics of new PVC heat stabilizer system. 　　　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. The experiments show that, the main Influencing factors are the grinding time, grinding temperature, baking time and baking temperature. During the synthesis of complexes, the influencing factors such as the CLa(NO3)3、CNaOH、nOH-：nHL and reaction time. We analyze a variety of factors and levels by orthogonal experimental method and finally determined the optimum 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. Through the static method and dynamic method to screen the objective coordination compound. At the same 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 maleamic acid 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, slightly worse than organic tin. Compound with several other non-toxic heat stabilizers, which find that complex of lanthanum (Ⅲ) with N-hexadecyl maleamic acid, has a good synergistic effect with calcium stearate, pentaerythritol and organic tin. According to the synergistic effect,having prepared composite heat stabilizer. After testing the compound heat stabilizer not only has excellent thermal stability, but also can enhance the mechanical properties of PVC products. Through infrared spectrum and color change of PVC in the heating process, we speculate the thermal stability mechanism of complex of lanthanum (Ⅲ) with N-hexadecyl maleamic acid 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 of conjugated polyene. Moreover, due to the special electronic shell structure of La3+, it can produce coordination compound through reaction to HCl which from the release of PVC and reduce the catalysis of HCl to rearrangement reaction. The organic part of the coordination compound can occur Diels-Alder addition reaction with conjugated polyene from the degradation of PVC. This reaction can eliminate conjugated chains in PVC molecules and enhance the flexibility of PVC molecular chain. Therefore, it perfect the color of the PVC material and the transparency of product. And it also has a good synergy with other traditional non-toxic stabilizers.