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چکیده
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The microencapsulation of ammonium azide particles (NH4N3) with fibrous nitrocellulose has been carried out through a solvent/non-solvent procedure which is based on the coacervation principle. X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetry–differential thermal analysis and differential scanning calorimetry techniques were used to characterize the structure, morphology and thermal stability of treated ammonium azide particles. Taguchi L-9 orthogonal array design method was exploited for assessment of effectiveness of experimental parameters on the coating properties. The investigated parameters were percent of coating agent, addition time of non-solvent, volume of non-solvent and stirring speed of the mixture (revolutions per minute, rpm). The individual effect of each parameter on the thermal stability of NH4N3 particle, determined by thermal analysis methods, was quantitatively evaluated by the analysis of variance. The statistical results revealed that the most stabilized coated NH4N3 particles can be obtained by using 2 % (w/w) of nitrocellulose as coating agent and by adding of 70 mL n-hexane as non-solvent within 50 min under stirring at 90 rpm, where the sublimation temperature of treated sample increases about 60 C with respect to uncoated one and reaches to 186.5 C. Also, the kinetic parameters of the sublimation processes of pure and microencapsulated NH4N3 particles that stabilized at this condition were obtained from the differential scanning calorimetry data by non-isothermal methods proposed by ASTM E696. Finally, the results of this study illustrated that the efficiency of the proposed chemometric method is higher than that of sequential experimental technique.
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