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Thermal Decomposition of Energetic Materials 85: Cryogels of Nanoscale Hydrazinium Diperchlorate in Resorcinol‐Formaldehyde
Author(s) -
Tappan Bryce C.,
Brill Thomas B.
Publication year - 2003
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.200390011
Subject(s) - thermal decomposition , materials science , scanning electron microscope , fourier transform infrared spectroscopy , decomposition , chemical engineering , particle size , formaldehyde , analytical chemistry (journal) , composite material , chemistry , organic chemistry , engineering
The objective of this work was to try to desensitize an energetic material by using sol‐gel processing and freeze drying to incorporate the energetic material into the fuel matrix on the nano (or at least submicron) particle size scale. Hydrazinium diperchlorate ([N 2 H 6 ][ClO 4 ] 2 or HP 2 ) and resorcinol‐formaldehyde (RF) were chosen as the oxidizer and fuel, respectively. Solid loading up to 88% HP 2 was achieved by using the sol gel‐to‐cryogel method. Various weight percentages of HP 2 in RF were characterized by elemental analysis, scanning electron (SEM) and optical microscopy, T‐jump/FTIR spectroscopy, DSC, and drop‐weight impact. SEM indicated that 20–50 nm diameter HP 2 plates aggregated into porous 400–800 nm size clusters. Below 80% HP 2 the cryogels are less sensitive to impact than physical mixtures having the same ratios of HP 2 and RF. The decomposition temperatures of the cryogels are higher than that of pure HP 2 , which is consistent with their lower impact sensitivity. The heat of decomposition as measured at a low heating rate increases with increasing percentage of HP 2 . The cryogels and physical mixtures release similar amounts of energy, but the cryogels exhibit mainly a single exotherm by DSC whereas the physical mixtures showed a two‐step energy release. Flash pyrolysis revealed gaseous product ratios suggestive of more energy being released from the cryogels than the physical mixtures. Cryogels also burn faster by visual observation.