Compatibility and thermokinetics studies of octahydro- 1,3,5,7-tetranitro-1,3,5,7-tetrazocine with polyether-based polyurethane containing different curatives

ABSTRACT

A compatibility of energetic compound with polymeric matrices is of prime importance in the pre-formulation stage for developing of new energetic composite formulations. In the present work, the compatibility of octahydro-l,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with polyether (PET) polyol (trade name SP-755)-based polyurethanes (PUs) containing different curatives such as 4,4ʹmethylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), and toluene diisocyanate (TDI) has been studied by using a differential scanning calorimetry method. The PET-based PUs were prepared by polymerization between PET polyol and different curatives, then these PUs were further mixed with HMX to study the compatibility and kinetic parameters. Results show that the compatibility and thermal stability are significantly influenced by the different curatives, and suggested thermals stability by thermal data follow the order for a mixture of HMX/SP-755/MDI > HMX/SP-755/TDI > HMX/SP-755/IPDI > HMX/SP-755/TMDI. The thermal degradation kinetics has also been investigated through non-isothermal conditions using the Kissinger and the isoconversional ASTM E689 kinetic methods. The finding shows that there was a significant variation in the apparent activation energy for a mixture of HMX/SP-755/MDI, HMX/SP-755/IPDI, HMX/SP-755/TMDI, and HMX/SP-755/TDI, which were 365.8, 257.7, 134.9, and 241.1 kJ mol⁻¹, respectively. The apparent activation energies obtained from the Kissinger method at maximum peak temperature are in reasonable agreement and consistent with isoconversional ASTM E689 kinetic method.

KEYWORDS:

• Octahydro-l-tetranitro-1-tetrazocine
• polyether polyol
• compatibility
• thermal degradation
• kinetics

Acknowledgments

The authors express their thanks to Dr. Manjit Singh, Distinguished Scientist/director, and N. Mukherjee for their constant motivation, guidance, and fruitful discussion. The authors are also thankful to Mahesh Kumar and T.C Sharma for their kind support for providing thermal analysis.