原位一步合成CuAl-LDHs-聚磷酸铵及其在聚丙烯阻燃中的应用

采用原位一步法合成铜铝类水滑石（CuAl-LDHs），通过控制铝酸钠/聚磷酸铵（NaAlO₂/APP）的质量比（0.82~3.28）合成CuAl-LDHs-APP。采用XRD、FTIR、SEM和TG对所制备的CuAl-LDHs及CuAl-LDHs-APP进行表征。采用极限氧指数（LOI）、垂直燃烧（UL-94）测试、弯曲及拉伸试验等考察了CuAl-LDHs/聚丙烯（PP）及CuAl-LDHs-APP/PP复合材料的阻燃性能及力学性能。SEM 观察表明:LDHs结构为片状，随着NaAlO₂与APP质量比的减小，CuAl-LDHs-APP颗粒粒径相应减小，当NaAlO₂与APP的质量比为0.82时，CuAl-LDHs-APP颗粒粒径达到20 nm左右，比表面积为183.5 m2/g。TG分析表明:CuAl-LDHs-APP在高温下有较好的热稳定性。当PP中加入质量分数为20%的CuAl-LDHs及CuAl-LDHs-APP时，LDHs/PP复合材料表面形成炭层；当NaAlO₂与APP质量比不大于1.64时，CuAl-LDHs-APP的添加可抑制PP燃烧时产生的熔滴现象；与CuAl-LDHs/PP复合材料相比，CuAl-LDHs-APP/PP复合材料具有更好的阻燃性能和力学性能；与PP材料相比，CuAl-LDHs-APP/PP复合材料的弯曲强度和拉伸强度等力学性能的下降也不明显。 

One-pot in situ synthesis of CuAl-LDHs-ammonium polyphosphate and application in polypropylene as flame retardant

One-pot in situ approach had been employed to prepare Cu-Al layered double hydroxides (CuAl-LDHs). Through controlling the mass ratio (0.82-3.28) of sodium aluminate/ammonium polyphosphate (NaAlO₂/APP), CuAl-LDHs-APP was prepared. XRD, FTIR, SEM and TG were utilized to characterize the prepared CuAl-LDHs and CuAl-LDHs-APP. The fire retardancy and mechanical properties of CuAl-LDHs/polypropylene (PP) and CuAl-LDHs-APP/PP composites were evaluated by limiting oxygen index (LOI), vertical burning (UL-94) test , as well as flexural and tensile tests. SEM observation indicates that the structure of LDHs is sheet-like, with the mass ratio of NaAlO₂ and APP decreasing, the particle size of CuAl-LDHs-APP reduces accordingly, when the mass ratio of NaAlO₂ and APP is 0.82, particle size of CuAl-LDHs-APP reaches about 20 nm, with specific surface area of 183.5 m²/g. TG analysis shows that CuAl-LDHs-APP has preferable thermostability at high temperature. When 20% mass fraction of CuAl-LDHs and CuAl-LDHs-APP is added in PP, the surface of LDHs/PP composites is covered with char. When the mass ratio of NaAlO₂ and APP is no more than 1.64, the addition of CuAl-LDHs-APP can suppress the melting drop phenomenon caused by PP combustion. CuAl-LDHs-APP/PP composite has superior flame retardant and mechanical properties compared with CuAl-LDHs/PP composite. Decreases of mechanical properties of CuAl-LDHs-APP/PP composite such as flexural strength and tensile strength etc. are not obvious compared with PP materials.