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5 R F Stengel , Des. News, 36, No. 16, 68 (1980).6. H . H . Cha u et al., Rev. Sci. Instr um., 5_ii, No. 12, 167 6 (1980).

V I B R A T I O N - I N D U C E D D E C O M P O S I T I O N O F T R I N I T R O B E N Z E N EN. P. Loginov, S. M. Murato v,a n d V. B . E p i f a n o v

A v a i l a b l e d a t a o n t h e k i n e t i c s o f v i b r a t i o n - i n d u c e d d e c o m p o s i t i o n o f s ol i d s c o n c e r n T N T,a m m o n i u m p e r c h l o r a t e , a n d c o l l o x y l i n [i , 2 ]. I n p a r t i c u l a r , i t h a s b e e n e s t a b l i s h e d f o r T N Tt h a t d e c o m p o s i t i o n o c c u r s w i t h a h i g h e r r a t e a t l o w t em p e r a t u r e s, l e s s t h a n i t s m e l t i n gt e m p e r a t u r e , t h a n i n t h e l i q u i d p h a s e a t T = 4 7 3 K .

T h e p u r p o s e o f t h i s w o r k i s to s t u d y t h e e f f e c t o f t h e v i b r a t i o n p a r a m e t e r s o n t hed e g r e e o f d e c o m p o s i t i o n a n d t h e r e a c t i o n r a t e i n t h e s o l i d p h a s e a n d t o o b s e r v e t h e p r e s e n c eo f c o n d e n s e d p r o d u c t s o f d e c o m p o s i t i o n i n s a m p l e s ( r e m a i n i n g a f t e r v i b r a t i o n ) o f t r i n i t r o -b e n z e n e ( T N B) b y m e t h o d s o f i n f r a r e d a n d u l t r a v i o l e t s p e c t r o s c o p y .

A 0 . l - g s a m p l e o f T N B ( F ig . i ) w a s i n s e r t e d b e t w e e n r o l l e r s i n th e a p p a r a t u s 3 a n d t h e ni n t o a n a i r t i g h t c h a m b e r 4 , p l a c e d o n t he p l u n g e r o f a h y d r a u l i c p r e s s 5 , w h i c h a l s o s e r v e da s a b a s e f o r t h e v i b r a t i o n u n i t w i t h t h e v i b r a t o r i . T h e h y d r a u l i c p r e s s c r e a t e d a s t a t i cl o a d; a c y c l i c l o a d w a s c r e a t e d f o r a f i x e d t i m e i n t e r v a l w i t h t h e h e l p o f t h e v i b r a t o r . I nt h e c o u r s e o f t h e e x p e r i m e n t s t h e d i f f e r e n c e i n t h e g a s p r e s s u r e i n t h e a i r t i g h t c h a m b e r w a sm e a s u r e d w i t h t h e h e l p o f a l i q u i d m a n o m e t e r , w h i l e t h e t e m p e r a t u r e o f t h e s a m p l e a n d o f t h eg a s w a s m e a s u r e d w i t h t h e r m o c o u p l e s . W h e n t he v i b r a t i o n a c t i o n c e a s e d , r e s i d u e s o f s a m pl e sw e r e r e m o v e d f r o m th e r o l l e r d e v i c e s a n d s a m p l e s f o r a n a l y s i s w e r e e x t r a c t e d f r o m t h em .

T h e e x p e r i m e n t s w e r e p e r f o r m e d w i t h v i b r a t i o n a l l o a d i n g w i t h f r e q u e n c i e s o f f = 4 5 a n d8 0 H z; t h e a m p l i t u d e o f t h e v i b r a t i o n s e q u a l e d i . i a n d 2 .5 m m , r e s p e c t i v e l y ; t h e s t a t i cp r e s s u r e P s t = 1 2 . 8 a n d 1 9 . 2 M P a ; a n d , t h e d y n a m i c l o a d s P d = 3 7. 0 a n d 4 8 . 0 M P a . T h e d a t ao b t a i n e d ( Fi g . 2 , w h e r e a is t he d e g r e e o f d e c o m p o s i t i o n a n d T i s t h e v i b r a t i o n t i m e) s h o wt h a t a s f i n c r e a s e s ( an d, t h e r e f o r e , P d i n c r e a s e s ) t h e d e g r e e o f d e c o m p o s i t i o n o f T N B i n c r e a s e sa n d o v e r 3 0 se c o f v i b r a t i o n a l l o a d i n g i t r e a c h e s 0 . 8 % o f t h e s t a r t i n g q u a n t i t y o f e x p l o s i v e .C o m p a r i s o n o f t h e r a t e o f v i b r a t i o n - i n d u c e d d e c o m p o s i t i o n w i t h t h e r at e o f t h er m a l d e c o m p o -s i t i o n i n d i c a t e s t h a t t he d e c o m p o s i t i o n r e a c t i o n i s s h ar p l y a c c e l e r a t e d b y t h e v i b r a t i o n a ll o a d i n g . I n a d d i t i o n , m e a s u r e m e n t o f t h e t e m p e r a t u r e o f t h e c o n d e n s e d s a m p l e i n t h e c o u r s eo f t he v i b r a t i o n s w i t h t h e h e l p o f t h e r m o c o u p le s w i t h a 1 0 0 - 2 0 0 - ~ m j u n c t i o n s h o w e d t h a t t h eh e a t i n g o f th e s a m p l e s d o e s n o t e x c e e d 1 5 - 3 0 K . T h e r e f o r e , t h i s a m o u n t o f h e a t i s n o t e n o u g hf o r h e a t i n g t h e T N B u p to t h e m e l t i n g p o i n t T m e l t a n d e s p e c i a l l y f o r i t s c h e m i c a l d e c o m p o -s i t i o n i n t h e s o l i d s t a t e w i t h s i g n i f i c a n t r a t e s , e x c e e d i n g b y a f a c t o r o f i 0 0 - I 0 0 0 i t s r a t eo f d e c o m p o s i t i o n a t h i g h e r t e m p e r a t u r e s i n l i q u i d p h a s e ; t h i s is d i f f i c u l t t o e x p l a i n f r o m v i e w -p o i n t o f c u r r e n t i d e a s r e g a r d i n g k i n e t i c s o f t h e r m a l d e c o m p o s i t i o n i n s o l i d p h a s e [ 3, 4 ].

T A B L E i. R e s u l t s o f A n a l y s i s o f t h e I R S p e c t r a o f T N B

TNB

St a r t i n gA f t e r tr e a t m e n t , s e e

/ = 4 5 H zA f t e r t r e a tm e n t , s e c? = 80 Hz

700 --3 900"--3 [ 1060--10( b e n z e n e r i n g )

1 0 5 1 07oo) 900)~.03 I ,o(-7oo) 0oo)t 0 9 t 0(7 io) (9 io)

Ratio o f a b so rp t i o n

0,87(1070)0,92(Io~o)0.95(1075)

1s4o- 5( - - N Q )

(I335)0 J 5(i3s0)

,50(13~5)

1440(c=c)0.13(1440i0 . t 5(t435)0 , t 2('1445)

N o t e. T h e a b s o r p t i o n b a n d s a r e i n d i c a t e d i n p a r e n t h e s e s .K u i b y s h e v ~ T r a n s l a t e d f r o m F i z i k a G o r e n i y a i V z r y v a , V o l . 24 , N o . i, p p . 1 3 0 - 1 3 2 , J a n u -

a r y - F e b r u a r y , 1 9 8 8 . O r i g i n a l a r t i c l e s u b m i t t e d J u n e 1 6, 1 9 8 6.1 2 0 0 0 1 0 - 5 0 8 2 / 8 8 / 2 4 0 1 - 0 1 2 0 5 1 2 . 5 0 9 1 9 8 8 P l e n u m P u b l i s h i n g C o r p o r a t i o n

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F

PSI: 5Fig 1

~e

1o 2 seeFig. 2

T h e t h e o r y of e x c i t a t i o n o f t h e e x p l o s i o n o f s o l i d s t o e x p l a i n t h i s a n o m a l o u s b e h a v i o ro f T N B , i n p a r t i c u l a r , t h e i d e a o f t h e a p p e a r a n c e o f l o c a l f o c i o f h e a t i n g w i t h a t e m p e r a t u r ea b o v e t h e f l a s h p o i n t , c a n n o t b e a p p l i e d i n t h i s c a s e b e c a u s e T m e l t , w h i c h i s t h e l i m i t o fh e a t i n g u n d e r c o m p a r a t i v e l y l o w p r e s s u r es , r e m a i n s v i r t u a l l y c o n s t a n t . I n a d d i t i on , t h em e c h a n i c a l w o r k p e r f o r m e d w i l l a t f i r st b e e x p e n d e d o n m el t i n g , a f t e r w h i c h i t w i l l b e e x -p e n d e d o n h e a t i n g t h e l i q u i d p h a s e u p t o t h e t e m p e r a t u r e o f t h e o n s e t o f i n t e n s e t h e r m a ld e c o m p o s i t i o n .

T h e o b s e r v e d a c c e l e r a t e d v i b r a t i o n - i n d u c e d d e c o m p o s i t i o n o f T N B i n t h e s ol i d p h a s e a tl o w t e m p e r a t u r e s s h o u l d p r o b a b l y b e a t t r i b u t e d t o t h e s p e c i f i c e f f e c t o f t h e c y c l i c l o a d ,w h i c h c o n s i s t s o f a s h a r p r e d u c t i o n o f t h e y i e l d s t r e s s o f c r y s t a l s , t h e a p p e a r a n c e o ff a t i g u e - r e l a t e d p h e n o m e n a a c c o m p a n i e d b y i n t e n s i v e f r a c t u r i n g o f p a r t i c l e s w i t h t h e f o r m a t i o no f f r e s h s u r f a c e s w i t h a h i g h c o n c e n t r a t i o n o f p o t e n t i a l a c t i v e c e n t e r s , t h e c r e a t i o n o ff a v o r a b l e c o n d i t i o n s f o r th e f o r m a t i o n, d i s p l a c e m e n t , a n d a c c u m u l a t i o n o f d i s l o c a t i o n s , a n ds p o n t a n e o u s m o t i o n o f d i s l o c a t i o n s a c c o m p a n i e d b y t h e f o r m a t i o n o f m i c r o a n d m a c r o s c o p i cc r a c k s. I t i s w e l l k n o w n t h a t m e c h a n o c h e m i c a l p h e n o m e n a p l a y a l a r g e r o l e in t h e a c t i v a t i o no f c h em i c a l p r o c e s s e s i n in o r g a n i c o x i d i z e r s a n d i n p o l y m e r s a c c o m p a n y i n g p u l v e r i z a t i on ,f r a g m e n t a t i o n , a n d v i b r a t i o n a l t r e a t m e n t [ 5 ] . I t i s s i g n i f i c a n t t h a t f a t i g u e d e f e c t s a r i s i n gi n p r e c e d i n g l o a d i n g c y c l e s c a n p a r t i a l l y h e a l o w i n g to c o m p a c t i o n i n s u h s e q u e n t l o a dc y c l e s . A s a r e s ul t : o f t h i s , c h e m i c a l - r e a c t i o n c e n t e r s c a n b e q u e n c h e d i n s o m e s e c t i o n s o ft h e s a m p l e a n d r e a p p e a r i n o t h e r s e c t i o n s i n r e p e a t e d l o a d i n g a n d u n l o a d i n g c y c l e s .

T h e c h a n g e s i n t h e c h e m i c a l c o m p o s i t i o n o f T N B s a m p l e s a f t e r v i h r a t i o n w e r e s t u d i e d b ym e t h o d s o f i n f r a r e d ( IR ) a n d u l t r a v i o l e t ( U V ) s p e c t r o s c o p y. F o r U V s p e c z r o s c o p y d i l u t e s o -l u t i o n s o f s a m p l e s i n e t h y l a l c o h o l ( c o n c e n t r a t i o n o f 0 . 0 0 1 g / l i t e r ) w e r e p r e p a r e d , w h i c he n a b l e d d e t e r m i n i n g t h e q u a n t i t a t i v e c h a n g e i n t h e a b s o r p t i o n s p e c t r u m o f T NB a f t er v i b r a t i o ni n t h e 2 2 5 - c m - I b a n d c o m p a r e d w i t h t h e a b s o r p t i o n s p e c t r u m o f th e s t a r t i n g T N B . T h e s i g n i f i -c a n t d r o p i n t h e r a t e o f d i s s o l u t i o n o f t h e v i b r a t i o n - t r e a t e d T N B s h o u l d b e n o t e d ; i t c a n a l s os e r v e a s a n i n d i r e c t p r o o f o f t h e c h a n g e i n t h e c h e m i c a l c o m p o s i t i o n .

band in te ns i t ie s I /~o o - e ra - t )

t530--+10 I t610+10--NO2, C= C) [ C=C , - -NO~)

t84o__.5c = c )

0,38i525)0,48i520)0,83i540)

i , 0 6i610)i 2 0t605)1 3 1i620)

0,16i840)0.151830)OA31840)

2800__+20C--H)0,052800)0,082780)0,042830)

3 C--H)0 A3000)0,422990)0,313030)

3600(C--H,O--H)

0.053600)0 A 23600)0A 23600)

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The data from UV spectroscopy showed that the relative intensity of absorption droppedby 9.7 at f = 45 Hz and by 21.4 at f = 30 Hz compare d with the starti ng sam ple of twicerecrystallized T NB . This indicates unequivocally that the chemical composition of thevibration-treated TNB samples changed.

Table i shows the result s of the inv estigat ion of TN-B by the metho d of IR spectro-scopy on a Spektrom om-2000 apparatus. The analysi s of the IR absor ption s pectra of thestarting and vibration-worked TNB showed that in separate bands of the spectrum, in particu-lar, in the bands at 1340, 1520, 1600, and 3000 cm ~, the absor pti on intensity changes, andsome bands are shifted relative to the starting spectrum of TNB. According to the data of[6], the 1340-c m I band should be attributed to stretching (symmetric) vibra tions of the NO2group, wh ile the 1520- and 1600-cm l bands should be attributed to stretching (antisymmetric)vibra tion s of the NO2 group.

Aside from the indicated changes in the intensity of absorption i n hands correspondingto vibrations of the NO2 group, the absorption intensity in the vibration-treated samplesin the 3000-cm I band, associated with the vibration of the Cr-H group in the benzene ring,increases, though to a lesser extent; th e intensity of abso rpti on in the 3600-c m 1 band,correspo nding to vibrat ions of the OH group, also increases. In the latter case the effecton the change in the absorption intensity could indicate hot the appearance of adsorbedmoist ure in the samples, which is unlikely, since TNB is not hygroscopic, and liberati on ofwater as a condensed product of the decomposition reacti on of TNB under the conditions ofvibration.

The change in the intensity of absorption in the 700 and 1060-cm I bands after vibrationalworking should also be noted; it indicates the possibility of a stable change in the internalenergy of the benzene ring.

Thus vibrational working changes the chemical properties and structure of the startingTNB with comparatively small vibrational loads and accelerates the decomposition of TNB inthe solid phase. This should be taken into account in any attempts to predict its stability.

LITERATURE CITED

2.3.4.6.6.

N. P. Loginov , S. M. Murat ov, and N. K. Nazar ov, Fiz. Go re ni ya Vzryva , I_~2, No. 3, 410(1976).N. P. Loginov , S. M. Muratov, and N. K. Nazar ov, Fiz. G or eni ya Vzry va, i_~4, No. 5, 154(1978).K. K. Andreev, Thermal Decomp ositi on and Combus tion of Explosives [in Russian], Nauka,Moscow (1966).Yu. Ya. Maksimov, in: Theory of Explosives [in Russian], No. 53, Mosc ow (1967).N. K. Baramboim, Mecha noche mistr y of Polymers [in Russian.], Rostekhiz dat, Mosc ow(1961).L. Bellamy, New Data on the IR Spectra of Comple x Mole6 ules [Russian translation], Mir,Moscow (1971).

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