Lattice Dynamics of Heated Nitramines.
Abstract
The laser Raman spectra of the four known polymorphs of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) have been recorded. Comparison of the spectra show that beta-HMX contains a different ring conformation than do alpha, gamma and delta-HMX. Alpha, gamma and delta-HMX have conformations which are similar to one another. The phase transition behavior between the polymorph forms was studied at slow heating rates and the results with transition temperatures being given parenthetically are: beta to delta (> or = 140 C, alpha to delta(147-160C), gamma to delta (> 205C). For rapid heating rates (50 C/sec.) the results are: beta to delta (175 C), beta to delta (> or = 175 C), alpha to beta (> or = 185 C) and gamma to delta (> or = 170 C). The transition times at 25 C are: delta to alpha (< 24 hrs.), delta to beta (< 24 hrs.), gamma to beta (< 12 mo.), alpha to beta (< 12 mo.). Gamma-HMX appears to contain more anharmonicity in its vibrational motions and this may explain why it does not form thermally from the other polymorphs, but readily converts to delta-HMX upon heating. Research on RDX heating rates and polymorphs has been undertaken, recently, along with spectral examination of the decomposition products of HMX.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1977
- Accession Number
- ADA050382
Entities
People
- Thomas B. Brill
Organizations
- University of Delaware