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Thermoanalytical studies on CTPB‐NH 4 ClO 4 composite solid rocket propellants
Author(s) -
Prasad M. R. R.,
Krishnamurthy V. N.
Publication year - 1984
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.19840090503
Subject(s) - propellant , thermal decomposition , burn rate (chemistry) , materials science , differential scanning calorimetry , decomposition , rocket propellant , solid fuel rocket , nitrogen , ammonia , reaction rate constant , analytical chemistry (journal) , calorimetry , chemistry , kinetics , thermodynamics , organic chemistry , physics , quantum mechanics
Premature reignition of controllable solid propellant motors, a factor affecting the extinguishment reliability, has been attributed to the first exotherm of NH 4 ClO 4 . Detailed studies were made (1) on suppressing the first exotherm of NH 4 ClO 4 with the use of materials like NH 4 BF 4 , NH 4 PF 6 , (NH 4 ) 2 TiF 6 etc. The present paper deals with the thermal decomposition kinetics of carboxy‐terminated polybutadiene (CTPB)‐NH 4 ClO 4 propellant with NH 4 BF 4 as an additive to suppress the first exotherm of NH 4 ClO 4 . The techniques employed in this study include: differential scanning calorimetry (DSC) for the thermal decomposition studies, and strand‐burner for the measurement of propellant burning rates. DSC experiments were conducted on the propellants at pressures of ambient, 17 kg/cm 2 and 40.82 kg/cm 2 ; at a constant heating rate under an inert atmosphere of nitrogen. The burning rate of the propellant samples were determined in the pressure range of ambient to 70 kg/cm 2 in an atmosphere of nitrogen. The burning rates were found to increase with pressure at each of the concentrations of the additive. The decrease in burning rate with the increase in concentration of the additive, at pressures of 35 kg/cm 2 and below is attributed to the excess of ammonia formed during the decomposition of both NH 4 ClO 4 and NH 4 BF 4 . At pressures above 35 kg/cm 2 , the increase in burning rate with the increase in concentration of the additive is attributed to the increased concentration of the metal ion (boron) in NH 4 BF 4 . These observations are in agreement with those of Mayer (1) et al., and Glaskova (2) .