改性钴镁铝类水滑石对乙烯-醋酸乙烯共聚物阻燃和力学性能的影响

Effect of Modified CoMgAl-LDHs on Flame Retardance and Mechanical Properties of EVA

采用共沉淀微波晶化法合成了不同量硬脂酸钠表面改性的钴镁铝类水滑石。X射线衍射测试指出合成的所有类水滑石晶体均有高的结晶度,d_(003)值证实了硬脂酸根和硝酸根离子没有插入到类水滑石的层间。红外光谱、扫描电镜和接触角测试均证实了随着改性剂用量的逐渐增加,类水滑石表面硬脂酸钠的负载量也逐渐增加。热分析表明改性剂的负载量对类水滑石的热降解温度有较大的影响。当类水滑石以总质量的20%的比例添加到乙烯-醋酸乙烯共聚物(EVA)中制成复合材料时,氧指数和力学测试指出钴离子的加入,使得钴镁铝类水滑石比镁铝类水滑石对复合材料氧指数和断裂伸长率均有明显的提高。硬脂酸钠以前驱体质量的2%进行改性的钴镁铝类水滑石/EVA复合材料的强度、韧性和阻燃性能表现最好。

The surface modified cobalt magnesium aluminium layered double hydroxides(CoMgAl-LDHs)containing different amounts of sodium stearate were synthesized by the coprecipitation microwave crystallization method.XRD characterization indicates that the sodium stearate surface modified LDHs has high crystallinity.The d(003)confirms that the stearate radical and nitrate ions have not been inserted into the interlayer of LDHs.FT-IR,SEM and contact angle measurements confirm that with the amount of modifier increasing gradually,the loading of sodium stearate on the surface of LDHs is also increased.Thermal analysis indicates that the amount of modifier has a greater influence on the thermal degradation of LDHs.The composite consists of LDHs and ethylene vinyl acetate copolymer(EVA),the loading of LDHs is kept at 20%in the composite.CoMgAl-LDHs can better increase the limiting oxygen index and the elongation at break of the composite in comparison with MgAl-LDHs due to addition of Co^2+.When the mass fraction of sodium stearate is 2%of the precursor,limiting oxygen index and mechanical measurements confirm that the composites have the best strength,toughness and fire retardance.