~Tc~ia'at~stion and Flame 145

Explosive Characterization of Dinitrotoluene

Donna Price, J. O. Erkman, A. R. Clairmont, Jr., and D. J. Edwards U. S. Naval Ordnance Laboratory, White Oak, Silver Spring, Maryland, U,S,A.

2,,LDil~itrotoluene (DNT) shows Group I explosive behavior, although it can be dead-pressed moderately easily, Its i~fihite diameter detonation velocity is approximated by D~ (mm//~sec) = 1.96 + 2.913p,), The detonability and shock ~¢h~itlvity of 3- 10 # DNT arc near those of production lots of high-bulk-density nitroguanidine and DATB. respectively.

][at~'aduetion Ao earlier paper [1] describes a classification ~I' high explosives into two groups. This charac- tc~-'i~ation, based on detonability as a function ~t' charge porosity, is less clear cut [2] than we ~rigin;tlly thought, but it still provides a con- veaieat and useful grouping. The purpose of the I~rcse~t work was such a classification of 2,4- di0itrotoluene, CH 3 .CoHa ' (N02) • (DNT).

Al~t~nt 10 years ago, Blinov [3,4,5] reported that dinitro compounds of aromatic hydrocar- batas exhibit an increasing critical diameter (t/0 ~'ith an increasing loading density (Po), that is, (]roup 2 behavior [I] . However, his meas- t a r~ents involved the decrease in height of a I¢~d cylinder against which his test charge was t~r~¢l, This uninstrumented test can give only i~0~lit.ect evidence of detonation or failure of the test explosive. It follows that his conclusions, dr~wr~ from such evidence, might be incorrect.

Although D N T is a common ingredient of !ar~l~ellants and of dynamites and is readily rtv~ilable in relatively pure form, there exist v e r y few data on its explosive behavior. Hence

it was an obvious dinitro aromatic to choose for a classification study and a check of Blinov's conclusions. The studies reported here are of detonation velocity (D), shock sensitivity, and detonability, each as a function of p0. None is exhaustive, but the studies combine to provide a characterizatior~ of DNT unavailable else- where.

Experimental Procedure Two lots of 2,,-5-dinitrotolucne, tech., were used. They contained 97.5 per cent (or more) DNT and had a melting point of 68.5°C or higher. (The pure material melts at 70°C and has a crystal density of 1.52 g/cc [6].) These batches of coarse DNT were designated X5 and NI : they had average particle sizes of 150 ,u and 350/~, respectively, by sieve analyses. A portion of batch X5 was recrystallized to prepare a batch of fine (3-10 ,u) DNT, X6.

Charge preparation and handling were iden- tical to those in previous work [ 1 ], as was record reduction. Charges were of various diameters,

Combustion & Flame. 14, 145-14g (1970) Copyright ,el 1970 by The Combustion Institute

Published by American Elsevier Publishing Compuny, Inc.

146

20.32 em long, and boostered by 5 0 - 5 0 pentol i te cylinders (P0 = 1.56 g/co) o f the same diameter and 5~08 c m long. The ins t rumentat ion was a 70-mm smear camera wi th wri t ing speed up to

4 mm/#sec.

R e s u l t s a n d D i s c u s s i o n

Unconf ined, coarse: D N T could not be init iated to steady-state de tonat ion in charges o f d < 7.6 crn. The pe:ntolite booster easily induced a vig-

orous react ion in such charges, bu t the resultant front velocity faded slowly at low Po and rapidly at high p, . (Consequently optical measurements o f D were m a d e on the fine D N T or on an 8 0 - 2 0 mixture o f coarse D N T mixed with the more

Table I , Delonatioa Velocity Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Detonation Density Diameter Velocity (D),

(Po). g/ce Preparation" (d). cm mm/psc¢

Fine DNT (X6) (voidless density 1.52 g/co) 1.302 A 3.81 1.301 A 5.08 1.301 A 7.62

D~ ( 1.301 g/co) = 5.75 mm/l~sec 1.506 B 2.54 1.507 B 3.50 1.511 B 5,08 1.495 B 7.62

D~ (1.507 g/cc~ = 6.35 mm/psec 1.00i C 5.08 1,001 C 7.62 I. 157 A 5.08 1.226 A 5.08 1.408 A 5.08 151 I B 5.08 5.864

Coarse DNT (X5)/RDX,SO/20 (voidless density 1.57 g/cc) 1.560 B 2.54 5.934 t' 1.558 B 3.50 6.573 1.556 13 5.08 6.699 1.554 B 7.62 6.751

Dr (I.556 g/cc) = 6.90 mm/psec

" A Hydraulic press. B. Isostatic press. C. Handpack. )' Point below line chosen tbr extrapolation. "Corrected for Po to 5.850 mm/psec. a Corrected for Po to 6.075 mm/psec.

, Fail

-I o 1.57 g/cc) a.O

3.0

Donna Price, J. O. Erkman. A. R. Clairmont. Jr., and D. J. Edwards

powerful explosive, R D X (cyclotrimethylene t r ini t ramine) .

De tona t ion velocity measurements are given in T a b l e 1, which a lso lists the ideal value Dt

ob ta ined a t several densities by the usual pro- cedure o f l inear ex t rapola t ion o f D versus d -~

to infinite d iameter . I f we m a k e the cus tomary

assumpt ion that the D t versus P0 curve for D N T is l inear , the two DI values o f Tab le 1 give

Dt (mm/#sec) = 1.96 + 2.913p~ ( I )

as the infinite d iamete r relat ionship for D N T .

Equa t ion 1 is conf i rmed by the D values

measured on 8 0 - 2 0 D N T - R D X mixtures at 99.2 per cent T M D . F r o m the D i value at this porosi ty and the addi t ivi ty rule for explosive mixtures [7] , the der ived value for pure D N T is

D~ (1.508 g / c c ) = 6 . 3 5 mm/#sec. At the same density, Eq, I predicts 6,44 mm/psec. This is an

acceptable check because Eq. 1 was derived from

5.120 5.33{)

6 : ; - 5,395 5.700 5'864~ 6.032 a

//: 3,751 S 4.685 .~ 5,512 g /

/ /

I i . . . . I .__ D,8 I,D 1.2 L4

LOADING DENS I[Y [5tcct Figure I. Pattern of detonation versus density curves lbr

DNT ( & d = 7.62 cm; @ d = 5,08 cm).

Explosive Characterization of Dinitrotoluene

Table 2, Detonabigty Data for Fine DNT (X6)

Density (Pol, g/cc Diameter (d). cm

-I- - + -

1.000 1.000 7.62 5.08 1.160 I. 160 5.08" 2.54 1,300 1,300 3.81" 2.54 1.400 1.400 5.08 2.54 1.506 1.514 2,54 2.54

" Results suggest that Ihis value is very dose to d~,

very few data and because technical-grade DNT was used in the mixture.

The data of Table 1 are plotted in Fig. 1 to display the pattern of detonation velocity versus porosity curves for DNT. It is clearly the pattern of behavior for Group I explosives [1]. So too is the trend of the present detonability results, given in Table 2: decreasing d e with decreasing porosity.

Shock sensitivity results, obtained with the NOE' ~landard card gap test [8], arc presented in Table 3. These determinations were made on coarse DNT, but pin tests were also run to show that this material detonated in the test confinement. Even so, the results indicate that D N T is approaching a dead press condition at 98.9 per cent T M D in this test. (When the con- fined test charge is scaled down by a factor of 0.7, failure occurs between 92.6 per cent and 96.7 per cent TMD.) Sensitivity results on the coarse material can be considered a good ap-

Table 3. Shock Sensitivity of Coarse DNT

NOL Gal~ Test [18] Percentage of 50"~ o Point

Voidless Density. . . . . Po, gice 4~/o TMD No. Cards P,. kbar

1.20b 79. I 144 ."2,5 1.27b 83,7 137 35.4 1.40b 91.8 115 43,7 1.49e 98.1 85 55.9 1.50¢" 98,9" 24" 105"

" DNT (XS): all other charges were DNT {Nil,

147

proximation to those that the fine material would exhibit because the effect of particle size on P~j is relatively small and practically disap- pears at a high percentage of TM D [2],

Chemically, DNT is very similar to TNT. The extremes in possible decomposition reactions indicate that it will have 82-99 per cent of the detonation energy of TNT and the same volume of gas products on a per gram basis. Hence DNT would be expected to be very like TNT in its ideal detonation behavior. The similarity of Eq. I to the analogous one for TNT [9] at 0.9 -< Po -< 1.53 g/ec:

Di (mm/ttsec) = 1.87 + 3.187Po (2)

justifies this expectation. Compatation methods successful in predicting D~ versus Po for TNT should be equally successful for DNT.

Similarity in D~ versus Pn does not imply similarity in sensitivity and detonabiiity. The drop-weight test result for DNT is negative: therefore D N T is harder to ignite than TNT and should exhibit lower shock sensitivity and prob- ably higher d c values. The dead press phenome- non observed here immediately suggests a de- tonability behavior like that observed for a high bulk-density nitroguanidine (NQ-h), which dead-presses in the gap test configuration and also produces a negative result in the drop weight te~t. The fine DNT (3-10 ~t) does in fact show d~ values near those of the NQ-h [2]. Al- though its detonability curve is not U-shaped, as is that of Lhe NQ-h, it seems to be approach- ing a minimum near 100 per cent TMD. A slightly coarser DNT might show its minimmn and dead pressing at lower p~: as did the NQ-h, The shock sensitivity of DNT is lower than that of TNT and higher than that of NQ-h: of the materials already tested [I] , it is nearest to that of DATB (diaminotrinitrobenzene).

In conclusion, the explosive behavior of DNT is characteristic of that shown by Group I materials. The statement to the contrary in the literature is incorrect in regard to DNT and probably the other dinitro aromatics us well.

148 Donna price. J. O. Erkman. A. R. Clairmont, Jr.. and D. J. Edwards

We are indebted to K. G. Shipp o f the U. S. try and Technology, No. 4. 640 (1058). Translation not

Naval Ordnance Laboratory for the preparation

of the batch o f fine DNT.

References 1. PRICE, D.. Eleventh Symposium (International) on Com.

bustion, pp. 693-703. Combustion Institute: Pittsburgh (1967).

2. PR c~. D . and CLA RMOr, tT, J r , A R., Twelfth Symposium (International) on Combustion. pp. 761-770, Combus- tion Institute: Pittsburgh (1969).

3. BLINOV, I. F., Scientific Reports of Higher School Chemi.~-

available. 4. BI.tNOV. I. F.. Khim. From.. 1959. 419-25 through AEC-

tr-5528. • 5. BLINOV. 1. F.. anti Sv~t.ovA, L. M.. in "Theory of ex-

plosives," Sb. Statei (OBORONGIZ), Moscow (1963). through AD 605-706.

6. McCRor~E, W. C.. Anal. Chem.. 26. 1848 (1954). 7. PRICE, D.. Chem. Rev.. 59. 801 (1959). 8. PRZCe, D.. and JAFFE, I.. ARS J.. 31,395 (1961). 9. URIZAR. M. J.. JAM~t. Jr.. E.. and SMITH. L. C.. Phys.

Fluids. 4. 262 (1961).

(Received September 2. 1969)