Thermal decomposition of energetic materials 71: Structure-decomposition and kinetic relationships in flash pyrolysis of glycidyl azide polymer (GAP)

Journal Article · Sun Mar 01 04:00:00 EST 1998 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(97)00162-4· OSTI ID:619588

Arisawa, H; Brill, T B ^[1]

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1. Univ. of Delaware, Newark, DE (United States). Dept. of Chemistry and Biochemistry

Glycidyl azide polymer (GAP) is a well-known energetic binder/plasticizer in rocket propellant and gas generator applications. Well-characterized, purified samples of glycidyl azide polymer (MW {approx_equal} 700) having 1, 2, or 3 terminal {single_bond}OH groups were flash pyrolyzed (dT/dt = 800 K/s) to 540--600 K under 2 atm Ar by T-jump/FTIR spectroscopy. The volatile products identified from the condensed phase were CH{sub 4}, HCN, CO, C{sub 2}H{sub 4}, NH{sub 3}, CH{sub 2}O, CH{sub 2}CO, H{sub 2}O, and GAP oligomers. IR-inactive N{sub 2} is, of course, also present. The low MW products result from homolysis of the heavy atom bonds and H-atom migration, as opposed to heavy atom recombination reactions. After N{sub 2} release, the relations between the mole fractions of the products and the parent GAP structure were determined. The NH{sub 3} content increases with the {single_bond}OH content, which suggests that NH{sub 3} is mostly formed by the end-chain azide groups. The hydrocarbon mole fractions correlate with the structure of the parent sample of GAP. CO appears to form from both the parent polymer and secondary sources, such as CH{sub 2}O and CH{sub 2}CO, at higher temperature. The HCN/NH{sub 3} ratio increases with increasing temperature. By using the product mole fractions and heat of formation of GAP, the calculated heat of decomposition is found to be three times larger than that measured by DSC ({minus}0.43 kcal/g). The relatively low reported flame temperature during combustion reflects the limited number of secondary exothermic reactions that are possible among the products. If it occurs during combustion, the apparent release of some GAP oligomers observed during flash pyrolysis would raise the flame temperature by allowing the decomposition of some of the GAP in the gas phase.

• OSTI ID: 619588
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 4 Vol. 112; ISSN 0010-2180; ISSN CBFMAO
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
AMMONIA
AZIDES
CHEMICAL REACTION YIELD
COMBUSTION KINETICS
FLASH HEATING
MOLECULAR STRUCTURE
PLASTICIZERS
PYROLYSIS