Donald L. Ornellas
2390
The Heat and Products of Detonation of Cyclotetramethylenetetranitramine,
2,4,6-Trinitrotoluene, Nitromethane, and Bis[2,2-dinitro-2-fluoroethyl]formal· by Donald L. Ornellas
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Lawrence Radiation Laboratory, University of California, Livermore, California
946S0
(Received October 26, 1967)
Three pure CHNO explosives covering a wide range of oxygen balance and one fluorine-containing explosive were fired in a detonation calorimeter. Product compositions and heat releases were obtained that are representative of the isentropic expansion of the detonation products. Energies ranged from 1095 to 1480 cal/g. Products varied from those containing no solid carbon to those containing more than 50% of the total carbon as solid. Observed products were compared to those calculated with the best available thermodynamichydrodynamic computer codes.
Introduction Calorimetric measurements combined with product a precise method for obtaining fundamental information about the detonation process. This information can then be used to provide normalization and boundary conditions for thermodynamic-hydrodynamic codes that predict explosive analysis offer
performance. Three pure CHNO explosives and one fluorinecontaining explosive were investigated. This work is an extension of the work reported2 for PETN. Jointly, these studies span the range of oxygen balance3 in explosives that is of greatest interest. Previous detonation calorimetric work with 2,4,6trinitrotoluene (TNT)4-7 and cyclotetramethylenetetranitramine (HMX)8 is not amendable to theoretical interpretation because of the geometries used or the lack of reliable product information. No information concerning the experimental determination of the heat and products of detonation of nitromethane (NM) and bis[2,2-dinitro-2-fluoroethyl]formal (FEFO) has been found in the literature.
Experimental Section Apparatus and Operation. The apparatus and its operation have been described;2 however, some changes have been made. The thermometric system is a quartz thermometer which has a sensitivity of 10-4° for differential measurements, is easily calibrated, and has direct digital readout. The heat equivalent of the standard instrument, taken as the average of six calibration runs, was 15,193 ± 2 cal/deg. All errors quoted are twice the estimated standard deviation of the mean. Charges are now completely confined by a 1.27-cm thickness of gold. Formerly the ends of the confining cylinder were left open. Since the bottom of the interior of the bomb was most damaged by flying The Journal of Physical Chemistry
fragments, it was protected by a stainless steel disk, 0.64 cm thick and 6.4 cm in diameter, which we replaced after each experiment. In order to contain NM under vacuum conditions, we sealed the gold cylinder 1.27 cm from each end with a translucent film which is a laminate of 0.025-mm polyethylene and 0.013-mm Mylar. A vacuum-tight seal was obtained by compressing the film between appropriately machined gold surfaces. The weight of film averaged 0.017 g/experiment. All charges were fired using the detonator previously described.2 Because of differences in the initiation characteristics of the explosives studied, various sizes of boosters were required. Boosters were made of PETN having a density of 1.71 g/cm3, and their weight was kept to a minimum. No booster was required for the TNT experiments, since initiation was effected by means of the detonator alone. HMX and FEFO required 0.3-g boosters and NM required a 0.75-g booster. Explosive Materials. Military specification, grade II HMX was used. Analyses by thin layer chroma(1) Work performed under the auspices of the U. S. Atomic Energy Commission. Work presented in part at the Joint Symposium of the Divisions of Fuel and Physical Chemistry on Detonations and Reactions in Shock Waves, 154th National Meeting of the American Chemical Society, Chicago, 111., Sept 1967. (2) D. L. Ornellas, J. H. Carpenter, and S. R. Gunn, Rev. Sci. Instrum., 37, 907 (1966). (3) If the generalized molecular formula of an explosive is CaH&NcOdF,,, then the oxygen balance to the carbon dioxide level is OB (%) = d 2
