Anti-hygroscopic surface modification of ammonium nitrate (NH4NO3) coated by surfactants

Ammonium nitrate surface is extremely hygroscopic, due to high energy on its surface which increases the potential of the molecules to absorb moisture from the surrounding environment. Ammonium nitrate particles were modified using second coating process with myristic acid in the different amount. The hygroscopicity was tested for ammonium nitrate with and without coating. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) were used to characterize the surface of coated and uncoated ammonium nitrate. Meanwhile, the method determined mass ratio of coating layer was improved to achieve more accuracy. In addition, focused ion beam technique was used to determine the thickness of coating layer. The results indicated that by using second coating modification method of surfactant adsorption, the anti-hygroscopicity performance of coated samples was significantly improved. The result showed that the decline of the absorption moisture rate was 40.57%, and the mass ratio of the coating layer was 1.42%. These results suggest that the second coating process employed could provide the well fundamental for the further anti-hygroscopic surface modification of ammonium nitrate particles coated by surfactants.