Further Decomposition Pathways of Mixtures
of the Nitramines HMX, RDX and CL20
with the Energetic Binder Glycidyl Azide
Polymer (GAP) - A Computational Study II

 

 

Manfred A. BOHN

Fraunhofer Institut für Chemische Technologie,
Energetic Materials Stability,
Joseph-von-Fraunhofer-Str. 7, D-76327 Pfinztal (Berghausen), Germany

Anton HAMMERL, Kate HARRIS and Thomas M. KLAPÖTKE

Department of Chemistry and Biochemistry,
Ludwig-Maximilians Universität München (LMU),
Butenandtstr. 5-13 (D), D-81377 München, Germany
e-mail: thomas.m.klapoetke@cup.uni-muenchen.de

Abstract:The energetic plasticizer glycidyl azide polymer (GAP) is used for new
types of rocket propellants which are formulated with the objective of achieving higher
burning rates. While the homolytic fission of an N-NO2 bond, which we discussed
previously, is energetically favored as the initial decomposition step, experiments
show that the decomposition of mixtures of the nitramines octahydro-1,3,5,7-tetranitro-
1,3,5,7-tetrazacyclooctane (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and
hexanitrohexaazaisowurtzitane (CL20) with a monomer of GAP-diol is more complex.
Therefore we investigated further possible decomposition pathways. Comparison of
the calculated activation energies for the decomposition of the mixtures with those for
the decomposition of the isolated nitramines shows that the presence of GAP-diol
decreases the activation energies of certain decomposition steps by up to 20 kJ mol-1.
GAP-diol facilitates the decomposition of CL20 and RDX to a larger extent than the
decomposition of HMX. However, the investigated decomposition pathways of GAP-diol
were inhibited by the presence of the nitramines.

Keywords: calculation, decomposition, energetic binder, nitramine, solid rocket propellants