Ammonium-nitrate-(AN-) based composite propellants prepared with a hydroxyl-terminated polybutadiene (HTPB)/polytetrahydrofuran (PTHF) blend binder have unique thermal decomposition characteristics. In this study, the burning characteristics of AN/HTPB/PTHF propellants are investigated. The specific impulse and adiabatic flame temperature of an AN-based propellant theoretically increases with an increase in the proportion of PTHF in the HTPB/PTHF blend. With an AN/HTPB propellant, a solid residue is left on the burning surface of the propellant, and the shape of this residue is similar to that of the propellant. On the other hand, an AN/HTPB/PTHF propellant does not leave a solid residue. The burning rates of the AN/HTPB/PTHF propellant are not markedly different from those of the AN/HTPB propellant because some of the liquefied HTPB/PTHF binder cover the burning surface and impede decomposition and combustion. The burning rates of an AN/HTPB/PTHF propellant with a burning catalyst are higher than those of an AN/HTPB propellant supplemented with a catalyst. The beneficial effect of the blend binder on the burning characteristics is clarified upon the addition of a catalyst. The catalyst suppresses the negative influence of the liquefied binder that covers the burning surface. Thus, HTPB/PTHF blend binders are useful in improving the performance of AN-based propellants. 1. Introduction Solid propellants are contained and stored in the combustion chamber of a solid rocket motor and are sometimes hermetically sealed in the chamber for long-term storage. Upon ignition, the propellants react to form hot gases within the chamber, which in turn are accelerated and ejected at a high velocity through a supersonic nozzle, thereby imparting momentum to the rocket motor. Solid rocket motors offer the advantage of having few moving parts. Therefore, they are used as propulsion systems for launch vehicles, spacecrafts, missiles, and other applications. There are various types of solid propellants, and a suitable propellant is selected to meet the requirements of each rocket motor application. A composite propellant is a solid propellant in the form of heterogeneous propellant grains composed of oxidizer crystals held together in a matrix of a synthetic or plastic binder. Ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) are widely used as an oxidizer and a binder, respectively, because AP/HTPB-based propellants have excellent burning and mechanical characteristics. One of the few serious drawbacks of AP-based propellants are the products of
References
[1]
G. P. Sutton, Rocket Propulsion Element, John Wiley & Sons, New York, NY, USA, 1992.
[2]
C. Oommen and S. R. Jain, “Ammonium nitrate: a promising rocket propellant oxidizer,” Journal of Hazardous Materials, vol. 67, no. 3, pp. 253–281, 1999.
[3]
Y. Hagihara, T. Ichikawa, H. Shinpo, and M. Suzuki, “Effects of chromium and cobalt compounds on burning rate of ammonium nitrate/hydroxyl-terminated polybutadiene composite propellants,” Science and Technology of Energetic Materials, vol. 52, no. 6, pp. 390–395, 1991.
[4]
H. Nakamura, M. Akiyoshi, K. Sakata, and Y. Hara, “Effect of metal complex catalysis of tetraaza-(14)-anurene on the thermal decomposition of ammonium nitrate and ammonium perchlorate,” Science and Technology of Energetic Materials, vol. 61, no. 3, pp. 101–107, 2000.
[5]
G. Singh and S. P. Felix, “Studies on energetic compounds: Part 36: Evaluation of transition metal salts of NTO as burning rate modifiers for HTPB-AN composite solid propellants,” Combustion and Flame, vol. 135, no. 1-2, pp. 145–150, 2003.
[6]
M. Quinn Brewster, T. A. Sheridan, and A. Ishihara, “Ammonium nitrate-magnesium propellant combustion and heat transfer mechanisms,” Journal of Propulsion and Power, vol. 8, no. 4, pp. 760–769, 1992.
[7]
V. P. Sinditskii, V. Y. Egorshev, A. I. Levshenkov, and V. V. Serushkin, “Ammonium nitrate: combustion mechanism and the role of additives,” Propellants, Explosives, Pyrotechnics, vol. 30, no. 4, pp. 269–280, 2005.
[8]
F. Nihal Tüzün and B. Zühtü Uysal, “The effect of ammonium nitrate, coarse/fine ammonium nitrate ratio, plasticizer, bonding agent, and Fe2O3 content on ballistic and mechanical properties of hydroxyl terminated polybutadiene based composite propellants containing 20% AP,” Journal of ASTM International, vol. 2, no. 6, pp. 233–245, 2005.
[9]
M. Kohga and S. Nishino, “Burning characteristics of ammonium nitrate-based composite propellants supplemented with ammonium dichromate,” Propellants, Explosives, Pyrotechnics, vol. 34, no. 4, pp. 340–346, 2009.
[10]
T. Kuwahara and N. Shinozaki, “Burning mechanism of ammonium nitrate/aluminum composite propellants,” Science and Technology of Energetic Materials, vol. 53, no. 3, pp. 131–136, 1992.
[11]
B. N. Kondrikov, V. E. Annikov, V. Y. Egorshev, L. DeLuca, and C. Bronzi, “Combustion of ammonium nitrate-based compositions, metal-containing and water-impregnated compounds,” Journal of Propulsion and Power, vol. 15, no. 6, pp. 763–771, 1999.
[12]
H. Murata, Y. Azuma, T. Tohara, et al., “The effect of magnalium(Mg-Al alloy) on combustion characteristics of ammonium nitrate-based solid propellant,” Science and Technology of Energetic Materials, vol. 61, no. 2, pp. 58–66, 2000.
[13]
B. E. Greiner, R. A. Frederick, and M. D. Moser, “Combustion effects of C60 soot in ammonium nitrate propellants,” Journal of Propulsion and Power, vol. 19, no. 4, pp. 713–715, 2003.
[14]
T. Kazita, T. Saito, T. Yamaya, M. Shimoda, and A. Iwama, “Ignition characteristics of GAP/AN/AP-based solid propellants for low pollution at sub-atmospheric pressures,” Science and Technology of Energetic Materials, vol. 57, no. 1, pp. 1–8, 1996.
[15]
K. Kato and G. Nakasita, “Burning rate characteristics of GAP/AN propellant,” Science and Technology of Energetic Materials, vol. 56, no. 3, pp. 130–134, 1995.
[16]
Y. Oyumi and E. Kimura, “IM characteristics of GAP/AN composite propellents,” Science and Technology of Energetic Materials, vol. 57, no. 1, pp. 9–13, 1996.
[17]
M. Takizuka, “Combustion characteristics of GAP based composite propellants (I)—theoretical combustion performance and burning rate,” Science and Technology of Energetic Materials, vol. 59, no. 4, pp. 181–191, 1998.
[18]
C. Nakajima, T. Saito, T. Yamaya, and M. Shimoda, “The effects of chromium compounds on PVA-coated AN and GAP binder pyrolysis, and PVA-coated AN/GAP propellant combustion,” Fuel, vol. 77, no. 4, pp. 321–326, 1998.
[19]
P. Sim？es, L. Pedroso, A. Portugal, I. Plaksin, and J. Campos, “New propellant component, part II. Study of a PSAN/ DNAM/HTPB based formulation,” Propellants, Explosives, Pyrotechnics, vol. 26, no. 6, pp. 278–283, 2001.
[20]
M. D. Judge and P. Lessard, “An advanced GAP/AN/TAGN propellant. Part I: ballistic properties,” Propellants, Explosives, Pyrotechnics, vol. 32, no. 2, pp. 175–181, 2007.
[21]
J. R. Goleniewski and J. A. Roberts, U.S. Patent 5783769-Solid Propellant with Non-crystalline Polyether/Energetic Plasticizer Binder, issued on July 21, 1998.
[22]
M. Kohga, W. Miyano, and T. Kojima, “Burning characteristics of polytetrahydrofuran-based composite propellant,” Journal of Propulsion and Power, vol. 22, no. 6, pp. 1418–1421, 2006.
[23]
M. Kohga and K. Okamoto, “Thermal decomposition behaviors and burning characteristics of ammonium nitrate/polytetrahydrofuran/glycerin composite propellant,” Combustion and Flame, vol. 158, no. 3, pp. 578–582, 2011.
[24]
M. Kohga, “Application of polytetrahydrofuran as a plasticizer of HTPB binder,” Science and Technology of Energetic Materials, vol. 71, no. 3, pp. 77–82, 2010.
[25]
M. Kohga, “Mechanical properties and burning characteristics of AP / HTPB composite propellant using polytetrahydrofuran as a plasticizer,” Science and Technology of Energetic Materials, vol. 71, no. 5-6, pp. 145–150, 2010.
[26]
K. Okamoto, M. Kohga, and K. Hasue, “Thermal behavior and tensile property of PTHF/HTPB blend,” Science and Technology of Energetic Materials, vol. 70, no. 4, pp. 87–93, 2009.
[27]
M. Kohga and K. Okamoto, “Thermal decomposition behavior of AN-based composite propellant with hydroxyl-terminated polybutadiene/polytetrahydrofuran blend as a binder,” Science and Technology of Energetic Materials, vol. 72, no. 6, pp. 161–168, 2011.
[28]
NASA Glenn's computer code Chemical Equilibrium with Applications, http://www.grc.nasa.gov/WWW/CEAWeb/.
