Study On The Technics Of Surface Modification Of Ammonium Nitrate

Ammonium nitrate were widely used in industry and agriculture production.But their application were highly restricted due to their gross hygroscopicity and caking capacity.In this paper ,three techniques include coupling agent, polymer liquid phase seperation, precipitation polymerization were employed to encapsulate ammonium nitrate.The coating effectiveness were characterized by SEM.The hygroscopicity and caking tendency of the coated AN were measured.The coating technics condition were studied by the orthodoxy design methed.The influence of the dryness temperature ,water content of AN and the add on of the coupling agent on coating effectiveness were emphasely sawed about.Under the optimised condition,the hygroscopicity of the modified ammonium nitrate reduced 38% and antipress intension reduced 65.3% compared to that of pure ammonium nitrate.The microscope morphology of the modified ammonium nitrate indicated that KH550 could form uniformity and continuous macromolecule membrane on the surface of ammonium nitrate.The modified effectiveness were obviously different when different coupling agent were employed. And the modified effectiveness were relatively poorer with KM602. than that of with KH550.Two kinds of duality copolymer were synthesized and followed by adopting liquid separation techniques to coated ammonium nitrate .The research result indicated that the modified effectiveness were not obvious when acrylonitrile-styrene duality copolymer were used.But the duality copolymer of acrylonitrile-ethyl acrylate can form relatively perfect coating layer on the surface of ammonium nitrate. The hygroscopicity of the modified ammonium nitrate reduced 27% and antipress intension decreased in evidence compared to that of pure ammonium nitrate.Precipitation polymerization of two monomer of acrylonitrile and methyl methacrylate were separately carried out to encapsulate ammonium nitrate .The influence of polymerization condition on performance of the coated ammonium nitrate was discussed.The experiment result indicated that modified effectiveness was not very well when methyl methacrylate was employed. In the relatively optimisedpolymerization condition ,polyacrylonitrile can form compact membrane on the surface of ammonium nitrate. The hygroscopicity of the modified ammonium nitrate reduced 37% and antipress intension decreased 65.3% compared to that of pure ammonium nitrate. The modified effectiveness of ammonium nitrate could be better when both surfactant and polymer were used together .The modified effectiveness of the surfactant TWEEN80 was better than that of SPAN80. The hygroscopicity of the modified ammonium nitrate reduced 54% and antipress intension reduced 83% compared to that of pure ammonium nitrate when both TWEEN80 and polyacrylonitrile were used together .The coated ammonium nitrate exhibited superior resistence to caking under common storage condition.