DSC and TGA Investigation on Ammonium Nitrate-Based Solid Propellant Doped with Ammonium Dichromate for Gas Generator Applications

Abstract

A typical solid propellant gas generator upon ignition will generate gas-phase combustion products and particulates that leave the generator through an exhaust line. The combustion products are at high pressure and temperature that can be tapped from the gas chamber to control the actuator system. This paper aims to investigate the Ammonium Nitrate (AN)-based gas generator propellants which are most suitable for low flame temperature and chlorine-free combustion products. Ammonium Nitrate is useful for slower burning rate and low flame temperature. Hydroxyl Terminated Polybutadiene (HTPB) was used as a binder and fuel, added to the oxidizer (AN). The ignitability of the propellants is increased by adding certain additives such as Ammonium Dichromate (ADC) and Guanidine Nitrate (GN) in the propellants, which have been studied. Five different propellant compositions were made and analyzed the effect of ammonium dichromate on propellants. Adiabatic flame temperature for the compositions has been determined by using C PROP-SHELL and it was obtained for a constant chamber pressure of 40 bar. For thermal analysis, STA (Simultaneous Thermal Analysis) was used to determine decomposition temperature from the DSC curve and mass loss from the TG curve. Each sample was heated from 30 °C to 600 °C at a heating rate of 27 K/min, and initial decomposition temperature and exothermic peak values were found. The change in mass of a sample with respect to temperature and time in the controlled atmosphere was measured by TGA. The influence of ADC and GN on the decomposition and thermal behavior of propellants has been investigated through this work.KeywordsHydroxyl Terminated Polybutadiene (HTPB)Ammonium Nitrate (AN)Ammonium Dichromate (ADC)Guanidine Nitrate (GN)Toluene Diisocyanate (TDI)Dioctyladipate (DOA)Differential Scanning calorimetry (DSC)Thermogravimetric Analysis (TGA)