Synergistic Anti‐Hygroscopic Modification of Ammonium Nitrate by Stearic Acid and Arachidic Acid

ABSTRACT

This study employed a solvent evaporation method to coat ammonium nitrate (AN) particles with a mixture of stearic acid and arachidic acid to mitigate their hygroscopicity. Results indicate that the mixed coating layer outperforms coatings consisting of single surfactants. Optimal coating efficiency was achieved under the following conditions: a stearic acid‐to‐arachidic acid mass ratio of 1:3, a total mixed‐solvent volume of 30 mL, an ether‐to‐acetonitrile volume ratio of 1:5, and a coating temperature of 40°C. Under these conditions, moisture absorption was reduced by 40.26%. The coated samples were characterized by a variety of techniques. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), raman spectroscopy (Raman), and x‑ray diffraction (XRD) confirmed that the coating agents were successfully introduced onto the surface of AN, while the crystal structure and polymorphic form of AN remained largely unchanged. Energy dispersive X‐ray spectroscopy (EDS) indicated a surface coverage of 47.39%–47.58%, while X‐ray photoelectron spectroscopy (XPS) showed an increase in the C1s/N1s ratio from 0.65 to 2.04. Furthermore, the coating did not significantly alter the decomposition temperature of AN, delayed moisture absorption by 6.64 h under identical conditions, and increased the water contact angle by 33.4°.