单分子层自组装技术应用于硝酸铵防吸湿的探讨

The octadecylamine was selected as a monolayer forming material and xylene as a solvent to increase the surface energy of ammonium nitrate. After monolayer self assembling through hydrogen bonding, Coulomb′s force and polarization action on the interface of xylene/ammonium nitrate, the octadecylamine at a concentration of 2×10 -4 mol/L in xylene can be considered to be self assembled on the surface of ammonium nitrate. The moisture absorption of the ammonium nitrate after surface modification has only 58% of that of the pure ammonium nitrate.

离子表面活性剂对膨化硝酸铵的改性

为了提高膨化硝酸铵的使用性能,研究了十二烷基苯磺酸钠(SDBS)和十八烷胺醋酸盐(OCTA·AC)两种离子表面活性剂以及两者的复配对膨化硝酸铵性能的影响,测试了改性前后膨化硝酸铵的吸湿性、吸油率、水溶性、抗结块性、微观结构以及热分解特性。实验结果表明,两种离子表面活性剂都可改善膨化硝酸铵的使用性能,尤其是将SDBS和OCTA·AC按照2∶3比例复配之后,对改善膨化硝酸铵的性能,效果最为明显,其测试结果为,在温度15℃和湿度90%环境中24 h的吸湿率为8%,比改性前的9.5%降低1.5%;吸油率为42.10%,比改性前的36.76%提高5.34%。SEM照片显示改性后的膨化硝酸铵微观结构的内表面比改性前光滑,表明离子表面活性剂吸附在膨化硝酸铵的内表面,形成单分子层或亚单分子层,降低了表面自由能。C80微热量热测试结果表明,离子表面活性剂对膨化硝酸铵的α斜方晶体转变为β斜方晶体有抑制作用。