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A t o m i c E n e r g y , V o L 7 6 , N o . 5 , 1 9 9 4

R A D I A T IO N R E S I S T A N C E O F P O L YM E R M A T E R I A L S1~. R . K i i n s h p o n t , V . K . M i l i n c h u k , a n d V . I . T u p i k o v U D C 6 6 . 0 1 8 . 8 6 ( 0 3 5 . 5 )The p rope r t i e s o f ma te r i a l s change unde r t he ac t i on o f i on i z ing r ad i a t i on . The degree o f change pe r un i t abso rbed

energy usual ly charac ter izes the radia t ion resistance of a mater ia l , i .e . , the capabi l i ty of the mater ia l to mainta in thenormal ized technica l indica tors wi thin establ i shed l imi ts . I t i s obvious tha t the most re l iable informat ion about the radia t ionre s i s t ance and se rv i ce l i f e o f a po lymer ma te r i a l i s ob t a ined by pe r fo rming t e s t s unde r na tu ra l cond i t i ons . Howeve r , sucht e s ts a re r a re because t hey a re expens ive , and o f t en t hey a re d i ff i cu lt t o pe r fo rm. For t h i s r ea son , t he re a r i se s t he p rob l emof s imula t i ng t he t e s t cond i t i ons .

An impor t an t ques t i on i s t he poss ib i l i t y o f pe r fo rming acce l e ra t ed t e s t s , s i nce t he ope ra t i ng t ime sca l e o f t hema te r i a l s c an d i f f e r by seve ra l f ac to r s f rom the t ime sca l e s o f t he t e s t s . The obv ious me thod fo r acce l e ra t i ng t e s t s byincreasing the dose ra te and reducing the exposure i s va l id in those cases when the radia t ion- induced changes in thecha rac t er i s t ic p rope r t i e s o f ma te r i a l s do no t depend o n t he absorbed dose r a t e . In t he opp os i t e ca se , i t is necessa ry t o knowthe dependence o f t he r ad i a t i on - induced changes on t he absorbed dose r a t e .

Bes ides t he r ad i a t i on env i ronm ent , t he op e ra t i ng cond it i ons a lso i nc lude t he comp os i t i on o f t he su r round ingmedium , t he t emp era tu re , t he mechan ica l l oads , and t he e l ec tromagne t i c f ie lds . M any o f t he se f ac to r s a f fec t the ma te r i a l stogether wi th the radia t ion, and the resul t of th is ac t ion i s not s imply addi t ive .

One o f t he ma in p rob l ems o f r ad i a t ion ma te r i a l s sc ience i s to cons t ruc t mode l s r equ i red fo r p red i c t ing t he changesin t he p rope r t i e s o f and de t e rmin ing t he r ea l se rv i ce l i f e o f ma te r i a l s . The cons t ruc t i on o f such mode l s i s ba sed on t heknowledge o f t he mechan i sm and k ine t i c s o f p rocesse s occur r ing i n ma te r i a l s . In t he absence o f such i n fo rma t ion (which ,a s a ru le , i s no t ava i l ab le ) on ly em pi r i ca l mode l s can be cons t ruc t ed , bu t t he i r r ange o f app l i ca t i on is u sua l l y l im i ted . Th eob jec t ive o f the p re sen t pap e r i s to cons ide r som e p rob l ems a r i s ing i n the a sse ssmen t o f t he r ad i a t ion r e s i s t ance o f m a te r i -a l s t ak ing i n to accoun t m ul t i f ac to r ope ra t i ng cond i t i ons .

C H A R A C T E R I S T I C I N D IC A T O R S O F T H E R A D I A TI O N R E S I S TA N C E O F M A T E R I A L SEvery ma te r i a l ha s a comp lex o f phys i ca l- chemica l p rope r t ie s . In connec t ion wi th t he func t i ons which a ma te r i al

mus t pe r fo rm , on ly ce r t a in o f i t s p rope r t i e s , name ly , t he ope ra t i ng p rope r t i e s , a re o f i n t e re s t. T he chan ge i n t he i nd i ca to rso f t he ope ra t i ona l p rope r t i e s o f m a te r i al s (phys i ca l -mechan ica l , e lec t rophys i ca l , t he rmophys i ca l , op t i ca l, and o the r s ) unde rthe ac t ion of ioniz ing radia t ion charac ter izes the i r radia t ion resistance . The charac ter is t ic indica tors of the radia t ionre s i st ance o f a po lyme r ma te r i a l we re i n t roduced i n accordance wi th GO ST 25645 .321-87 [1] . In mo s t c a se s , the com moncha rac t e ri s t ic i nd i ca to r s o f t he r ad i a t ion r e s i s t ance o f ma te r i a l s used fo r d i f fe ren t pu rposes a re t he phys i ca l -mechan ica lp rope r t i e s , a s s t a ted i n G OS T 25645 .331-91 [2 ], s i nce o the r i nd i cato r s become mean ing l e ss i n t he ca se o f r ad ia t i on - induceddamage to a ma te r i a l .

Eve ry ma te r i a l ha s many cha rac t e r i s t i c i nd i ca to r s . For example , a s t ruc tu ra l ma te r i a l u sed fo r e l ec t r i c i n su l a t i onhas 20 cha rac t e r i s t ic i nd i ca to r s [2] . A t t he same t ime , t he dependence o f t he cha rac te r i s t ic i nd i ca to r s on t he ab sorbed d ose( fo r i r r eve r s ib l e r ad i a t ion - induced e f fec ts ) o r t he absorbed do se r a t e ( fo r r eve r s ib l e e f fec ts ) i s , a s a ru l e , d i f f e ren t fo r a l lcharac ter is t ic indica tors . In other words, the radia t ion resistance i s usual ly de termined by one charac ter is t ic indica tor , forwhich t he t e rm "de t e rmin ing cha rac t e r i s t ic i nd i ca to r o f rad i a t ion r e s i s tance" (Tab le I ) was i n t roduced i n [2 ] .

The absorb ed dose ( and t he absorbed dose r a t e fo r i rr eve r s ib l e e f fect s ) fo r wh ich a cha rac t e r i s ti c i nd i ca to r changesby a def ini te amount i s used as a quant i ta t ive charac ter is t ic of radia t ion resistance . The re la t ive change of a charac ter is t icind i ca to r , depend ing on t he func t i ona l pu rpose o f t he ma te r i a l , i s c al l ed an a rb i t r a ry c r i t e ri on o f r ad i a t ion r e s i s t ance andthe dose a t which the arbi t rary cr i te r ion i s reached i s ca l led the radia t ion index (see Tables I and 2) .

Af f i l ia te o f t he L . Ya. Karpov Sc ienti fi c-Research Ins t i t u te o f Phys ica l Chem is t ry . T rans la ted f rom A tom nayaI~nerg iya , Vo l . 76 , No. 5 , pp. 42 2-4 28 , M ay, 1 994 . Or ig ina l a r t ic l e subm i t ted Janu ary 19, 1 994 .384 1063-4258 /94 /7605-0384512 .50 9 P l enum Pub l i sh ing Corp ora t i on

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TABLE 1 . Determ in ing Charac te r i s t i c Ind ica to rs o f the Rad ia t ion Res is tance o f Mater ia l sa n d Th e i r A r b i t r a r y C r it e ri a

Functionalpurposeof the material

Structural functions:forcepacking

GlueHeat-insulating, ncludingheat-shieldingTemperature-controlcoat-ingsRadiation shieldingofnuclear reactors

Determiningcharacteristicindicator of radiationresistance

Bending strength, MPaResidual deformationundercompression, %Rupture strength of a gluebond, MPaThermal conductivity,W/(m.K)Coefficient of absorption ofsolar radiationat wavelengthsfrom 0.2 to 2.5 /~mHydrogen content, mass %

Arbitrary criterionof radiationresistance, %

-5 0-2 0-5 025

50 for 100Thermal conductivity I0 > 1.2Specific heat capacity 45Density 5 0.01-0.03Tangent of the loss angle 1 3 0.1(1 kHz)Electric strength 3-6 1 > 10Radiation-inducedmass loss 10 1 500

S I M U L A T I O N O F T H E R A D I A T IO N E N V I R O N M E N TUnder actual operating conditions, materials can be subjected to ionizing radiation of different types (-y-radiation,

accelerated charge particles, neutrons) with, as a rule, a wide energy distribution. In laboratory tests for radiation resis-tance, one of the most important capabilities is to simulate the radiation environment, since in most cases it is incorrect toreplace radiation of one type by radiation of another type as well as the energy spectrum of the radiation and to switchfrom pulsed to continuous irradiation or vice versa, and any such changes must be substantiated. Usually, the volume-averaged absorbed dose under fixed irradiation conditions (average dose rate and t emperature, medium , and so on) is usedas a measure of the radiati on effect of ionizing radiation. The absorbed dose, however, is not always a unique measure ofsuch action, primarily because the energy of the ionizing radiation is reteased discretely and is limited to the region of thetrack. The a bsorbed dose rate in tracks is significantly higher than the volume-averag ed dose rate, and it depends on thecharacteristics of the ionizing radiation. If radiation processes depend on the absorbed dose rate (or the response of thesystem to the action of the radiati on is related nonlinea rly to the dose), then for the same volume-a veraged dose theradiation effects can be different. Radiation effects are often associated with linear energy transfer. This characteristic isone-dim ensional , and it does not describe the spatial pattern of the energy distri butio n in the volu me of the track. There-fore it also does not descri be the local concentration of intermediate active particles, whose reactions give rise to changesin the properties of the irradiated materials.

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T A B L E 3 . E f f e c t o f th e T y p e of Ionizing Radiation on t h e C h a n g e i n th e I n d i c a t o r s o f t h eM a c r o p r o p e r t i e s o f P o l y m e r s u n d e r I r r a d ia t io n [ 6 ]P o l y m e r

P o l y v i n y l c h l o r i d e

L o w - d e n s i t y p o l y e t h y -l e n eP o l y t e t r a f l u o r o e t h y l e n e

L o w - d e n s i t y p o l y e t h y -l e n e

P o l y t e t r a f l u o r o e t h y l e n e

D o s e , M G y

0 ,0 30, 10 ,313

0 , 0 I0 ,0 30 ,31 ,03 ,0

0,0010 ,0 0 30 , 0 t1 .02 ,0P o l y e t h y l e n e t e r e p h t h a l a t e

R a t i o o f t h e p o s t i r r a d i a t i o n p r o p e r t yi n d i c a t o r s t o t h e i n i t i a l i n d i c a t o r s

.~ - r a y s I p r o t o n s ( 'I '0 0 M e V ) ID i e l e c t r ic p r o p e r t i e s ( t a n ~ )

1 , 6 1 , 42,1 1,251 , 5 t 1 ,3

]4 .0 I 2 ,06 .3 2 ,3V o l u m e e l e c t r i c r e s i s t a n c e0 , 8 I0 .3

T e n s i l e s t r e n g t h1, 31, 20 .4 50 ,60 .4 50 ,3 50.710 .6 8

0 ,0010 ,0011, 30 , 9 50 ,4 50 , 2 50 ,1 80 , t 80 ,8 50 ,7 9

* E l e c t r o n s ( E = 2 M e V ) a n d p r o t o n s (E =

neutrons

2 ,25,02 ,21,451, 70,0010,001

0 ,9 50 ,9 50 ,7 5

0 ,5

8 M e V ) w e r e u s e d i n s t e a d o f y - ra y s .

Microd os ime t r i c concep t s , wh ich t ake i n to accoun t t he s tochas t i c natu re o f t he i n t e rac t i on o f t he r ad i a t ion w i th themed ium and the l oca l cha rac t e r o f t he ene rgy re l ea se , a l so do no t pe rmi t a comple t e exp l ana t i on o f t he d i f f e rences i n t hee f f i ci ency o f t he ac t i on o f d i f f e ren t t ypes o f r ad i at i on .

Sys t ema t i c i nves t i ga ti ons o f t he spec i f i c na tu re o f t he ac t ion o f i on i z ing r ad i a t i on o f d i f f e ren t t ypes (neu t rons f roma nuc lea r reac to r , a cce l e ra t ed p ro tons , -y -rays f rom 6~ and acce l e ra ted e lec t rons) on t he change i n t he p rope r t i e s o fpo lymer ma te r i a l s have made i t poss ib l e t o d raw some gene ra l conc lus ions [5 ] :

In t he gene ra l c a se , t he r ad i a ti on - induced changes i n t he p rope r t i e s o f po ly me r ma te r i a l s depend on t he t ype o fradia t ion: the grea test changes are charac ter is t ic for neut ron i r radia t ion;the d i f f e rences ow ing to t he t ype o f r ad i a t i on r each t ens o f pe rcen t , and i n sepa ra t e ca se s hundreds o f pe rcen t ;t he degree o f i nequ iva l ence o f t he ac t ion depends o n t he chemica l s t ruc tu re o f t he m ac romo lecu l e s , t he compos i t i on

of t he po lymer compos i t i ons , and t he phys i ca l s t ruc tu re o f t he po lymer and cha rac t e r o f t he su r round ing med ium.Inc rea s ing t he ab sorbed dose nu l l if i e s t he e f fec t o f t he t ype o f r ad i a t ion (Tab le 3 ) .

C O M B I N E D E F F E C T O F I O N IZ IN G R A D I A T I O N A N D O T H E R F A C T O R SDur ing op e ra t i on i n i on i z ing- rad i a t ion f i e lds , o the r ex t e rna l f acto r s a l so ac t on t he ma te r i a l s - t he env i ronment

(vacuum, a i r , l i qu id med ium) , t empera tu re , op t i ca l r ad i a t i on , e l ec t r i c and magne t i c f i e lds , mechan ica l l oads , and so on .Ma te r i a l s a re sub j ec t ed t o t he combined ac t i on o f i on i z ing r ad i a t i on and o the r ex t e rna l f ac to r s . Unde r combined ac t i on ,much s t ronge r changes a re obse rved i n t he p rope r t i e s o f ma te r i a l s t han unde r t he ac t i on o f on ly i on i z ing r ad i a t i on andex te rna l de s t ab i li z ing f ac to r s sepa ra t e ly [6 -11] .

En v i r on me nt . The en v i ronm ent changes i n t he p rocess o f i r r ad ia t i on a s a r e su lt o f bo th r ad io lys i s o f a i r andrad i a t i on - induced re l ea se o f ga s f rom the ma te r i a l s (Tab le 4 ) . Atmosphe r i c componen t s wh ich a re chemica l l y ac t i ve wi thre spec t t o po lymers a re : oxygen , ozone , and n i t rogen d iox ide . The l a s t two co r ros ive chemica l compounds a re a lwayspre sen t w hen ma te r i a l s a re i r r ad i a t ed i n a i r , s i nce t hey a re p roduc t s o f t he r ad io lys i s o f a i r . T he s t a t i ona ry concen t ra t i on o fozone dur ing i r r ad i a t i on o f a i r f a ll s i n the r ange 0 . I -0 .3 vo l . % [12]. Wh en ozone i n t e rac t s wi th po lym ers , t he m olecu l a rmass o f t he po lym ers dec rea se s and oxygen-con ta in ing g roups accumu la t e ( ca rboxy l , c a rbon y l , pe rox ide , and o the r s ). Int ime , su r face c racks fo r m and sp read ; u l t ima te ly th i s r e su lt s i n t he de s t ruc t ion o f t he po ly me r ma te r i a l. The r a t e o f ozoneag ing i nc rea se s i n t he p re se nce o f t ens il e s t r e sse s , wh ich open c racks and revea l new su r faces [13] .

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T A B L E 4

Polymer Compositionof hazardous gaseousproducts. % Radiation-chemical yieldPolyethylenePolypropylenePolyamidrPolycarbonatesPolyimidePolyvinyl chloridePolytetrafluoroethylenePolydimethylsiloxane

Hydrogen 95-98)Hydrogen (85-98), methane (2-12)Hydrogen 50-70), carbon monoxide (30-40)Hydrogen 2), carbon monoxide (50), carbondioxide (40)Hydrogen 20-30), carbon m onoxide (15-40), carbon dioxide (40-50)Hydrogenchloride 95 )Carbon monoxide, carbon dioxide, carbon tetraf luoride, perf luoroalkanesHydrogen (35-40), methane (30-60)

3 .2-4 .52.4-2.8

1.3-31. 3

2 00.45

2 . 5 - 3 9

The con ten t o f oxyg en in po lymers i n a i r i s (0 .3 -3 ) . 10 -3 mole s /kg , and t he r a t e a t wh ich oxy gen en t e r s t he po ly -mers i s de t e rmined by t he d i f fus ion coe f f ic i en t, wh ich a t 278-370 K l i e s in t he r ange 0 .04-15 cm2.sec - l . The mac ro -rad i ca l s fo rmed unde r t he ac t i on o f r ad i a t i on i n t he p re sence o f oxygen t r ans fo rm in to pe rox ide r ad i ca l s . The success iveal ternat ion of the reac t ions in which oxygen is a t tached to macroradica ls and reac t ions of peroxide radica ls i s charac ter izedby a cha in ox ida t ion p rocess , wh ich des t roys po lymers .

Op t i ca l R ad ia t i on . Seconda ry r ad i a t ion a r ise s du r ing t he i n te rac ti on o f e l ec t rons and p ro tons w i th ma te r ia l s ;neu t rons and x - ray b rem ss t rah lung a r i ses i n ine l a st ic co l li s i ons wi th t he a toms o f t he ma te r i a l ; and , when the ve loc i t y o fthe cha rged pa r t i c l e s i s h ighe r t han t he p ropaga t ion ve loc i t y o f l i gh t i n t he med ium, Che renkov-Vav i lov r ad i a t i on a r i se s .The pene t ra t i ng pow er o f r ad i a ti on o f t he se t ypes i s h ighe r t han t ha t o f t he p r imary cha rged pa r t i c l e s , and fo r t h i s r ea sonthe seconda ry r ad i a t i on can i nc rea se t he absorbed dose no t on ly i n ma te r ia l s i n t he p r im ary- rad i a t i on f i e ld , bu t a l so i nma te r i a ls beh ind sc reens .

Che renkov-Vav i lov r ad i a t i on a r i se s i n so l i ds and l i qu ids fo r e l ec t ron ene rg i e s o f abou t 0 .1 MeV and p ro tonenergies of about 100 M eV [14]. Usu al ly , l ight genera ted in the volum e of the mater ia l ac ts both on the ma ter ia l i t se l f andon the p roduc t s o f r ad io lys i s . U l t r av io l e t rad i a ti on can cause pho tochemica l degrada t ion o f t he m a te r i a l . Mo reove r , shor t -l i ved and s t ab l e p roduc t s o f r ad io lys i s , whose op t i ca l abso rp t i on spec t rum i s usua l l y sh i f t ed i n to t he l on g-wave l eng th r eg ioncom pared to the init ia l mater ia l , i .e . , these products extend the range o f pho tosens i t iv i ty of the mater ia l , a r i se in themater ia ls .

Deac t iva t i on o f exc i t ed mo lecu l es w h ich a re fo rm ed in the i n t e rac t i on wi th i on i z ing r ad i a t ion o r neu t ra l i z a ti on o fcharged par t ic les can a lso be an internal source of l ight in the i r radia ted mater ia l . I t has been establ i shed exper imenta l lytha t r ad io luminescence and recombina t i on l uminescence i n po lymers s t rong ly i n f luence t he r ad i a t i on -chemica l p rocesse s[15] . So, ioniz ing radia t ion combined wi th opt ica l radia t ion intensi fy the effec t (photoradia t ion effec t ) [6 , 7] .

Addi t ional destabi l iz ing fac tors ar i se when ioniz ing radia t ion interac ts wi th the mater ia ls of par ts . These fac torsinc lude the speci f ic chemical medium crea ted by the products of radiolysis of the mater ia ls [3 , 16] , e lec t r iza t ion ofmater ia ls [17] , secondary ioniz ing radia t ion, and opt ica l and UV radia t ion [14] induced by the effec t of ioniz ing radia t ion,and pu l se s o f mechan ica l s t r e sse s p roduced b y pu l se s o f i on i z ing r ad i a ti on (p re ssu re waves) [18 ].

E l ec t r i za t i on . One o f the ba s i c p rocesse s o f the i n t e rac ti on o f r ad i a ti on wi th ma t t e r i s i on i za t i on o f molecu l e s , a sa r e su lt o f wh ich e l ec t rons and pos i t i ve i ons (ho l es ) a re p roduced . The co ncen t ra t ion and mob i l i t y o f t he cha rged pa r t i c le sde t e rmines t he r ad i a t i on - induced e l ec tr i c conduc t iv it y , wh ich can va ry o ve r w ide l im i ts . The nonun i fo rm d i s t r ibu t i on o f t heabsorbed dose ove r t he vo lume o f t he ma te r i a l g ive s r i se t o d i f f e ren t i a l e l ec t ros t a t i c cha rg ing o f t he ma te r i a l s . A conse -quence o f t he d i f f e ren t ia l cha rg ing i s an e l ect r ic spa rk d i scha rge , w h ich can pene t ra t e i n to t he su r round ing space , a long t hesu r face ( above - o r be low -sur face ) wi thou t e scap ing i n to t he su r round ing space and t h roug h the l aye r o f d i e l ec t r ic on to t hesubst ra te (breakdown of the die lec t r ic ) . Elec t r ic discharges gradual ly dest roy mater ia ls . The e lec t r ic f ie lds ar i s ing dur inge l ec tr i z a ti on can i n f luence t he me chan i sm o f t he r ad i a ti on -chemica l p rocesse s and change t he d i s t r i bu t i on o f t he abso rbeddose of ioniz ing radia t ion in the mater ia ls .

Mechan ica l Loads . Po lymer ma te r i a l s i n pa r t s a re usua l l y i n a l oaded s t a t e o r t hey have i n t e rna l s t r e sse s , wh icha r i se fo r d if f e ren t r ea sons , i nc lud ing t he f ab r i ca ti on t echno logy . Th e e f fec t o f t he mechan ica l l oads changes t he m olecu l a rdynamics , t he s t ruc tu re o f t he po lym er cha in , and t he sup e rmolecu l a r s t ruc tu re . These changes a re r eve r s ib l e , i f t hemechan ica l l oads do no t g ive r i se t o chemica l changes . In t he p re sence o f r ad i a t i on , mechan ica l l oads g ive r i se t o new

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chemica l reac t ions in polym ers , a s a resu l t o f which a new i r revers ib le st at e of a polym er , which can not be achieved underthe ac t ion of ion iz ing rad ia t ion only , can a r i s e .

T h e m o s t e x t e n s iv e i n f o r m a t i o n h a s b e e n a c c u m u la t ed a b o u t t h e c o m b i n e d e f f e c t o f h y d r o s t a t i c c o m p r e s s io n a n dioniz ing rad ia t ion , g iv ing r i s e to a ch ange in the ra t e and d i rec t iona l i ty of rad ia t ion-chemica l reac t ions [19] . Fo r exam ple ,in polye thylen e and som e e las tomers , the e f fec t iveness of rad ia t ion- induced l inkage inc reases ; th i s l eads to s igni f i cantchanges of the phys ica l -chemica l and o pera t ing proper t i e s [8]. As a resu l t o f the com bined ac t ion of h igh-en ergy rad ia t ionand mechanica l loads , the re l axa t ion ra t e a f t e r remova l of the load and the c reep ra t e inc rease , and these ra t es depend onthe absorbed dose ra t e [3 , 4 , 9 , I0] . As a ru le , h igh-en ergy rad ia t ion acce le ra tes the degrada t ion o f a mate r ia l in s t ressedregions [20] .

In sum mary , i t should be noted tha t in format ion about the rad ia t ion res i s tance o f polym er mate r i a l s has beenobta ined main ly for s t andard condi t ions of i r rad ia t ion ( room tempera ture , monoenerge t i c rad ia t ion , a i r ) , and f rom thes tandpoin t of rad ia t ion mate r i a l s c i ence i t can be used only for making a pre l iminary choice of m ate r ia l s . Th e su i t ab i l ity ofmate r i a l s for va r ious opera t ing condi t ions can be de te rmined on the bas i s of the complex of ac t ing fac tors ( inc luding themedium and t empera ture ) and the func t iona l purpose of the mate r i a l .

Phys ica l fac tors , w i th respec t to which the mate r i a l s a re insens i t ive under ord inary condi t ions , can have a s t rongdes tab i li z ing e f fec t on the rad ia t ion- induced changes of the proper t i e s of poly me r mate r i al s . T he ab sorbed ene rgy of theradia t ion conv er t s the po lym er sys tem in to a nonequi l ibr ium s ta t e and makes the sys tem suscept ib le to ex te rna l ac t ions ,such as opt i ca l rad ia t ion , mecha nica l loads , e l ec t r i c and magne t i c f i e lds , and o thers .

LITERATURE CITED

1.

2.3.4 .5 .

6.7.8 .9 .

10 .11 .12 .13.14 .I5 .

B . A . Br i skm an, A . A . Volob uev, S . S . D ad 'yan , e t al . , "R adia t ion res i s tance of poly me r mate r i a l s . Terms anddef in i t ions . " GOST 25645.321-87 , Izd . S tandar tov , Moscow (1989) .B . A . Br i skman, A . A . V olobu ev, L . I . I skakov, e t a l . , "Polym er mate r i a l s . Radia t ion resi s t ance as ses smentr e q u i r e m e n t s . " G O S T 2 5 6 4 5 . 3 3 1 - 9 1 , I z d . S t a n d a rt o v , M o s c o w ( 19 9 1) .V . K . Mi l inchuk , V . I . Tu piko v, B . A . Br iksman, e t a l ., Hand book of the Radia t ion Res i s t ance of OrganicMate r i a l s [ in Russ ian] , l~nergoa tomizda t , M oscow (1986) .V . K . Mi l inchuk and V. I . Tupikov [eds . ] , Organic Radia t ion Chemis t ry , E l l i s Horwood, Chiches te r (1989) .B . A . Br i skm an and V. K . Mi l inchuk, " Inves t iga tion of the ac t ion of d i f fe rent types of ion iz ing rad ia t ions on theproper t i e s of polym ers , " in: P ro ceedings of the 1s t Al l -Union Confe rence on "Die lec t r i c mate r i a ls unde r ex t remecondi t ions , " J anuary 22-26 , 1990 Suzda l , (1990) , Vol . I I , pp . 239-256.V. K . Mi l inchuk , "P roblem s of the photoradia t ion e f fec t , " Khim. Vy s . l~nerg . , 19 , No. 4 , 326-337 (1985) .G . S . Zhd anov and V. K . M i l inchuk, Photoradia t ion Ef fec t s in Polym ers [ in Russ ian], NIITI~K HIM, Moscow(1980) .1~. R . Kl inshpon t and V. K . Mi l inchuk, "Poly me r mate r i a ls under condi t ions of the com bined e f fec t of ion izingradia t ions and o ther phys ica l fac tors , " Zh. V ses . kh im. o- va im. D . I . M ende leeva , 35 , N o. 5 ,61 8-6 25 (1990).V . V . M alaev and V. F . S tepanov, "Acc e le ra t ion of re laxa t ion proces ses in polym ers under i r rad ia t ion ,"Vyso kom olek . Soed . A , 30 , N o. 6 , 1275-1278 (1988) .V . V . Malaev an d V. F . S tepanov, "T emp era ture dependences of c reep and re laxa t ion proces ses in polye thyl -ene te rephtha la te und er i r rad ia t ion ," Khim. V ys . t~nerg . , 23 , No. 3 ,2 36 -2 40 (1989) .D . Phi l l ips , "Ef fec t of rad ia tion on poly me rs , " Mate r . Sc i . Technol . , 4 , No. I , 85-91 (198 8) .S . Ya . Pshezhe t sk i i and M. T . Dm i t r i ev , Radia t ion Phys ica l -Chemica l P roces ses in Ai r [ in Russ ian] , A tom izda t ,M o s c o w ( 1 9 7 8 ) .N . M . E ma nue l ' and A. L . Buch achenko, Chemica l Phys ics of Mo lecula r Des t ru c t ion and S tabi l iza t ion of Poly-mers [ in Russ ian] , Nauka , Mo scow (1988) .I . G . K aplan and N. V . Po lyanski i , "Poss ib le ro le of Vavi lov-C herenkov rad ia tion in rad ia t ion chemis t ry , " Khim.Vys . l~nerg . , 16 , No. 5 , 387-393 (1982) .I . P . She lukh ov, G . S . Zhd ano v, E . R . K l inshpont , and V. K . M i l inchuk, " In te rna l photoradia t ion e f fec t . Radia -t ion- induced luminescence and i ts e f fec t on rad ia t ion proces ses , " Khim. Vys . I~nerg . , 22 , No. 3 ,2 25 -22 8 (1988) .

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16 .17 .18 .19 .20 .

V. K . M ilinchu k, I~. R. K linshpon t, and V. I . Tup ikov, "R adiation resistance o f organ ic mater ials under conditionsof outer space," Kh im. Vy s. l~nerg., 25, No . 6, 483-492.S. G. Boev and V. Y a. U shakov , Radiation-Induced Charge Accu mu lation in Solid Dielectr ics and M ethod s for I tsDiagno stics [ in Ru ssian] , l~nergoatomizdat, M oscow (1991).I . I . Zalyub ovsk ii , A. I . Kalinichenko, and V. G. La zurik, Introduction to Rad iation Acoustics [ in Russian] ,Vishcha Shkola, Khar 'kov (1986).V. K . Mil inchu k and A. L. K ovarski i , "Radia t ion chemis t ry of polymers under h igh pressure , " in : High PressureChem is t ry and Physics of Polymers , CRC Press (1993) .G. S . Zhd anov , A. S . Smolyanski i , and V. K . M il inchuk, "Loca l iza tion of radia t ion damage in polymethylmethacrylate ," Khim. Vys. l~nerg. , 20, No. 1, 32-37 (1986).

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