镁-铝-镧三元类水滑石的制备及其在PVC中的应用

Synthesis and application of intercalated Mg-Al-La hydrotalcite in PVC

采用共沉淀-离心-水热法制备了结晶度高的镁-铝-镧三元类水滑石(MgAlLa-CO_3-LDHs),采用SEM、XRD对产物结构进行表征。探索了共沉淀温度、共沉淀时间、水热温度、水热时间对产物结构的影响。研究发现:在n(M^(2+))∶n(M^(3+))=2∶1、n(La^(3+))∶n(Al^(3+))=1∶23、溶液pH≥10的情况下,70℃共沉淀反应2 h,再在150℃下水热反应10 h,制备出典型层状结构、高纯度、晶型完整且层板堆积有序性高的镁-铝-镧三元类水滑石。将其作为稳定剂用于聚氯乙烯(PVC)加工,通过静态热烘箱实验、刚果红实验,研究其对PVC热稳定性能的影响。结果表明:镁-铝-镧水滑石能够大幅度提高PVC的热稳定性能。

High crystallinity and well distributed magnesium-aluminum-lanthanum ternary hydrotalcite （MgAILa-CO3-LDHs） was prepared by the coprecipitation-centrifugation-hydrothermal method.The phase composition and microstructure of the product were characterized by X- ray diffraction （XRD） and fi led emission scanning electron microscopy （SEM ） .The effects of coprecipitation temperature,coprecipitation time,hydrothermal temperature and hydrothermal time on the crystallization structure of the product were investigated.Results proved that when the solution pH≥ 10, n （M2＋） ：n（M3＋） =2：1, n（La3＋）：n（AP＋） = 1：23,and then coprecipitation reaction for 2 h at 70 % and following by hydrothermal reaction for 10 h at 150 %, lamellae magnesium-aluminum-lanthanum ternary hydrotalcite with typical layered structure,high purity,complete crystal form and high stacking order could be prepared. It was applied in the processing of polyvinyl chloride （PVC） as the thermal stability agent to study its influence on the thermal stability of PVC by heat oven aging method and congo red test.The results also showed that MgAILa-CO3-LDHs could significantly improve the thermal stability of PVC.