Title : Evaluation of mineral jelly as suitable waterproofing material for ammonium nitrate
Abstract:
Ammonium nitrate is a versatile inorganic salt. The innocuous nature of combustion products, low cost and easy availability makes it an attractive oxidizer to the propulsion community.However, its usage in high energy materials and space applications has been adversely affected mainly due to its hygroscopicity and phase transition phenomenon. This study explores the possibility of overcoming the problem of hygroscopicity of ammonium nitrate by coating the particles with selected waterproofing materials .Gravimetric analysis of the samples of ammonium nitrate coated with eight different waterproofing materials , vis-à-vis ,uncoated ammonium nitrate were conducted at different relative humidity and exposure time. The results indicate that mineral jelly is the promising waterproofing material for ammonium nitrate among the materials tested, viz. calcium stearate, dioctyl phthalate, kaoline, diethyl phthalate, dinitrotoluene, shellac varnish and bees wax. The superiority of mineral jelly as the waterproofing material to ammonium nitrate has been evaluated on the basis of differential thermal analysis and X-ray diffraction patterns. Further experiments Viz. infra red spectral analysis using FTIR and scanning electron microscopy also carried out to realize the validity. Suitability of mineral jelly as an additive for the gun propellant was also assessed on the basis of theoretical calculations using ‘THERM’ program. Attempts are also on to replace the ammonium perchlorate with ammonium nitrate so as to develop green composite propellant suiting the ecological requirements calling for HCL free burning for the future space applications.
Keywords: Hygroscopicity, phase transition, waterproofing ability, mineral jelly, ammonium nitrate, high energy materials, coating materials
