The Study Of Modifying Sepiolite And Its Effect On The Performance Of Ammonium Nitrate

In this paper,surfactant M reacted with chlorhydric acid,sulfuric acid,phosphoric acid by orthogonal experiments to synthesis canionic modifier SP-1,SP-2,SP-3,respectively.Sepiolite were modified by cantionic modifier SP-3,anionic surfactant sodium dodecylbenzenesulfonate(SDBS),stearic acid and organic silane coupling agentγ-aminopropyl triethoxy silane(KH550),respectively.The mechanism of modifiers had been explored prelimianryly.By using the organic-midified sepiolite applied to ammonium nitrate(AN) as modifier,we analysed the effect on structure and performance of AN resulting from modifier.Modified sepiolites were characterized by FT-IR,XRD,SEM,TG-DSC,Contact Angle and Moisture absorpion rate.The results showed that all four modifiers could make the sepiolite surface organiclized.However,differen modifying mechanisms lead to sepiolite layers changed differently.When canionic surfactant SP-3 modified sepiolite,some cantions were exchanged into pore of sepiolite and enlarged sepiolite interspace,the others were adsorbed on the surface to coat sepiolite.SDBS were adsorbed on the sepiolite surface by electrostatic attraction which tend to increase surface negative charge density,meanwhile,because of the large size,the alkyl chain of SDBS would prevent the molecules of water or other irons from entering the sepiolite interspace,causing the layer spacing decreased.Stearic acid were connected to the sepiolite by esterification with-OH on the suface,the hydrophobic groups of stearic acid arranged on the surface to reduce the surface tension of sepiolite,causing the layer spacing decreased.After hydrolyzation,KH550 reacted with Si-OH on the surface of sepiolite.A number of molecules of water in sepiolite structure tend to be lost by heating,but KH550,which didn't enter the sepiolite layer,would coat on the surface,causing the sepiolite layer spacing decreased.The result showed that modified sepiolite increased the contact angle and made the moisture absorption rate lower than unmodified sepiolite.Adding 1%and 3%SP-3 into the AN respectively,we analysed the effect of modifiers on the structure of AN by DSC and XRD ways.Meanwhile,we analysed the effect of different content of modifier on the hygroscopic rate of AN as well.The experiments indicated that the modified sepiolite might change the crstal,improve the decomposition temperature and crystal transition temperature and enhance the deformation of AN.Under 25℃,RH80%conditions,according to adding different modified sepiolite with varied content(1%,3%,5%) into the AN,we could see that the mositure absorption rate of modified AN had been apparently affected.1%SP-3 modified sepiolite,1%SDBS modified sepiolite,1%stearic acid modified sepiolite and 1%KH550 modified sepiolite caused the mositure absorption rate of AN decreased 63%,44%,64%,81%,respectively.