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A statistical study of the variables associated with the ozone cracking of elastomeric vulcanizates

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A statistical study of the variables associated with the ozone cracking of elastomeric vulcanizates

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Content A STATISTICAL STUDY O F THE VARIABLES ASSOCIATED W ITH THE O ZO N E CRACKING OF ELASTOM ERIC VULCANIZATES A T h esis P resen ted to The F a cu lty o f th e S ch ool o f E n g in eerin g The U n iv e r s ity o f Southern C a lifo r n ia In P a r t ia l F u lfillm e n t o f th e R equirem ents f o r th e D egree M aster o f S c ie n c e in Chem ical E n g in eerin g B y Donald Eugene M orris K -i - August 1965 U M I Number: EP41787 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, th ese will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI' Dissartation Publishing UMI EP41787 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 -1 3 4 6 £ O U ' N \ *2 * " 1 ^ This dissertation, written by Bonald..E^en© M orris,,................. under the guidance of hX&...Faculty Committee and approved by all its members, has been presented to and accepted by the School of Engineering in partial fulfillment of the re quirements for the degree of M aster o f S cie n c e in Chem ical E n g in eerin g Bate A u g u s tL l9 6 £ ............. Faculty Committee Chflyrma / O M - ........................ ACKNOWLEDGMENTS The author w ish es to ex p ress h is thanks to th e B. P . G oodrich Company fo r i t s support o f t h is p r o je c t, and to D r. E . G. P a rtrid g e and Mr. A. G. V e ith f o r t h e ir |te c h n ic a l d ir e c t io n . Thanks are a ls o due to Mr. J . R. i ;S c o tt f o r h i s e f f e c t i v e m aintenance o f our la b o r a to r y equipm ent. i i ABSTRACT Many workers have stu d ie d th e e f f e c t s o f such com pounding and t e s t in g v a r ia b le s as c r o s s - lin k d e n s ity , amount o f b la c k , amount o f p r o c e ssin g o i l , and th e d egree o f e lo n g a tio n ©r s t r a in on ela sto m er d eg ra d a tio n caused by |ozone a tta c k ; but th e re i s no p u b lish ed work on th e sim u l- Itaneous sy ste m a tic e v a lu a tio n o f th e s e v a r ia b le s . T his jpaper d e s c r ib e s an in v e s t ig a t io n o f th e in flu e n c e o f th e se fo u r v a r ia b le s on ozone crack in g th a t was c a r r ie d o u t (u sin g SBR l£OG as th e ela sto m er) by th e a p p lic a tio n o f a s t a t i s t i c a l ex p erim en ta l d e s ig n . The d a ta o f t h is program were an alyzed by th e se s t a t i s t i c a l m ethods, and th e r e - I s u i t s are d isp la y e d in th e t e x t in a co n v en ien t ta b u la r and g r a p h ic a l form . In g e n e r a l, the method proved to be f a i r l y good jfo r d eterm in in g th e r e la t iv e im portance o f th e v a r ia b le s i and th e in t e r a c t io n betw een them. The agreem ent betw een .th e ex p erim en ta l r e s u lt s and th e r e s u lt s c a lc u la te d by u se t !© f th e s t a t i s t i c a l tech n iq u es i s f a i r l y good. i i i I TABLE OP CONTENTS A C K N O W L E D G M E N T S . ....................... i i ABSTRACT . .......................................... . . i i i | LIST OP ILLUSTRATIONS . . ....................... v i |LIST OP TABLES . . . . . . . . . . . . . . . . . . . v i i i I ntroduction ............................ 1 M ETH O D S OF APPROACH . . ............................ 3 E xperim ental S tr a te g y Employed . • • . • • • * • 3 Measured R esponses . . . . . . . . . . . . . . . 7 EXPERIMENTAL PROCEDURE . . . . . ........................ . . . . 9 Sample P rep a ra tio n . . . . . . . . . . . . . . . 9 M ixing ............................. . . . . . . . . 9 C uring . ....................... 9 1 T e stin g o f P h y sic a l P r o p e r tie s . . . . . . 10 P relim in a ry Work . . . . . . . . . . . . . 10 Ozone T itr a tio n 10 Ozone C racking T e sts . . . . . . . . . .................... 12 S f8 0 0 'max • • • • • • • .......................... 12 j Creep T est . . . . . . ......................... 12 Crack Volume . ....................... . . . . . . . 1 3 ANALYTICAL PROCEDURE . . . . . . . . . . . . . . . . 34 RESULTS AND DISCUSSION ............................................19 R e su lts o f E xp erim en tal Runs.... ......................... 19 G raph ical D isp la y o f R e su lts 27 D is c u s s io n o f R e s u lts . . . . . . . . . . . . . Il 2 C r it ic a l Comment ................... . . . . . . . . . . . SU M M A R Y AND CONCLUSIONS.......................................... lj.8 Summary ................................ ij.8 C o n clu sio n s ................................. ij.8 Comments on S t a t i s t i c a l T e c h n i q u e .....................................50 i v V REFERENCES . . . . . . . . . . . . . ..................... .... 51 APPENDICES . . • ............................................................. %. A p p e n d ix I - S o u r c e s o f M a t e r i a l s U sed . . . . 55 A p p e n d ix I I - E x p e r im e n ta l D a ta . . . . . . . . 56 A p p e n d ix H I - S i g n i f i c a n c e o f C o e f f i c i e n t s . . . 6i|. A p p e n d ix IV - R e c ip e s and P h y s i c a l P r o p e r t i e s o f Com pounds . . . . . . . . . . . 67 LIST OP ILLUSTRATIONS F igu re 1 (SOC)max A fte r 1 Day V s. th e Independent V a ria b les 2 (SOC)max A fte r 3 Days V s. th e Independent V a ria b le s 3 (SOCQ^ny A fte r 5 > Days V s. th e Independent V a r ia b le s J j . Creep A fte r 6 Hours V s. th e Independent V a r ia b le s $ Creep A fte r 18 Hours V s. th e Independent V a ria b le s 6 Creep A fte r 3 -6 Hours V s. th e Independent V a ria b le s s 7 Crack Volume A fte r 6 Hours V s. the Independent V a ria b les 8 Crack Volume A fte r 12 Hours V s. the Independent V a ria b les 9 Crack Volume A fte r 2ij. Hours V s. th e Independent V a ria b les 10 Crack Volume A fte r 36 Hours V s. th e Independent V a ria b les 11 Crack Volume A fte r ij.8 Hours V s. th e Independent V a ria b les Vi LIST OP TABLES M a te r ia ls System L e v els o f Dependent V a ria b le s E q u ally Spaced C ross-L ink D e n s itie s E xperim ental D esign M atrix Dependent V a ria b le s in Coded U n its M atrix o f Independent V a ria b le s Average (SOC )m a 3 C V alues A verage Creep V alues Average Crack Volume V alues A n a ly sis o f D a ta -C o e ffic ie n ts fo r (SOC)max P r e d ic tio n A n a ly sis o f D a ta -C o e ffic ie n ts fo r Creep P r e d ic tio n A n a ly sis o f D a ta -C o e ffic ie n ts fo r Craek Volume P r e d ic tio n R e la tiv e C o e f f ic ie n t s f o r (SOG)majc P r e d ic tio n R e la tiv e C o e f fic ie n t s f o r Creep P r e d ic tio n R e la tiv e C o e f f ic ie n t s f o r Crack Volume P r e d ic tio n (SOC)max Measurements Creep Measurements Crack Volume Measurements v i i i Table 19 S ig n ific a n c e o f G o e ff ie ie n ts fo r (S00)max P r e d ic tio n — T - t e s t V alues 20 S ig n ific a n c e o f C o e f f ic ie n t s fo r Creep P r e d ic tio n — T - t e s t V alues 21 S ig n ific a n c e o f C o e f f ic ie n t s f o r Crack Volume P r e d ic tio n — T - t e s t V alues Page % i ! ! 6£ : 66 i INTRODUCTION I ; I n c r e a s e d c o n c e n t r a t i o n s o f o z o n e i n t h e a tm o s p h e re ! i n m any o f t h e u r b a n a r e a s an d t h e k n o w le d g e t h a t t h i s 1 o z o n e i s o n e o f t h e p rim e f a c t o r s c a u s in g c r a c k i n g an d I f a i l u r e o f r u b b e r a r t i c l e s u n d e r c o n d i t i o n s o f s t r e s s h a v e i J b r o u g h t a b o u t m any s t u d i e s to f i n d a v a l i d e x p l a n a t i o n o f t h e f a c t o r s i n v o lv e d i n t h i s d e g r a d a tio n * Some o f t h e im - | p o r t a n t f a c t o r s t h a t a r e known t o h a v e a n i n f l u e n c e o n . o z o n e c r a c k i n g a r e t e m p e r a t u r e , h u m id i t y , s t a t e o f c u r e , i i co m p o u n d in g i n g r e d i e n t s , c r o s s - l i n k d e n s i t y , e l o n g a t i o n , o z o n e c o n c e n t r a t i o n , an d t h e h i s t o r y o f t h e s a m p le s b e f o r e ; b e in g e x p o s e d . The p u r p o s e o f t h i s p a p e r i s t o d e s c r i b e a p ro g ra m w h ic h w as u n d e r t a k e n t o d e te r m in e t h e i n f l u e n c e o f f o u r o f t h e a b o v e v a r i a b l e s ( I n d e p e n d e n t v a r i a b l e s ) o n o z o n e c r a c k i n g ( d e p e n d e n t v a r i a b l e ) . T h e se f o u r v a r i a b l e s a r e c r o s s l i n k d e n s i t y , am o u n t o f c a r b o n b l a c k , am o u n t o f o i l , an d e l o n g a t i o n . T h e re a r e r e p o r t s i n t h e l i t e r a t u r e t h a t d e s c r i b e t h e e f f e c t s o f some o f t h e s e v a r i a b l e s t a k e n o n e a t a t im e ; h o w e v e r, t h e s e do n o t a n sw e r t h e q u e s t i o n a b o u t th e c o m b in e d e f f e c t s o f t h e s e v a r i a b l e s , i . e . t h e i r i n t e r a c t i o n w i t h e a c h o t h e r . T h is q u e s t i o n c a n b e a n s w e re d o n l y b y u s e o f some s y s t e m a t i c e x p e r i m e n t a l p ro g ra m , and 1 'a n s w e r s t o t h i s ty p e o f q u e s t i o n a r e o f g r e a t im p o r ta n c e f o r p r e d i c t i o n o f how e la s t o m e r s w i l l b e h a v e u n d e r s e r v i c e ; c o n d i t i o n s . The e x p e r i m e n t a l p ro g ra m e m p lo y ed f o r t h i s s t u d y I i n v o lv e s t h e u s e o f m o d e rn s t a t i s t i c a l t e c h n i q u e s . T h is m e th o d w as u s e d t o k e e p th e s i z e o f t h e p ro g ra m a t a m in i mum b y e f f i c i e n t u s e o f a l l d a t a c o l l e c t e d , a n d , a t t h e I sam e t im e , e v a l u a t e th e e f f e c t s o f a l l t h e v a r i a b l e s a s | w e l l a s s p e c i f i © i n f l u e n c e s o f o n e v a r i a b l e o n a n o t h e r . A s i n g l e m a t e r i a l s s y s te m w as u s e d th r o u g h o u t t h e s t u d y , an d i t i s h o p e d t h a t t h i s m ay d e s c r i b e i n a q u a l i t a t i v e m an n e r I t h e b e h a v i o r o f o t h e r s i m i l a r s y s te m s i n th e r a n g e o f t h e v a r i a b l e s s e l e c t e d * METHODS OP APPROACH E x p e r im e n ta l S t r a t e g y E m ployed The s i n g l e m a t e r i a l s s y s te m (o n e r e c i p e ) t h a t was s e l e c t e d f o r t h i s s t a t i s t i c a l s t u d y i s a t y p i c a l o n e an d i s show n i n T a b le 1 . As s t a t e d p r e v i o u s l y , t h e f o u r v a r i a b l e s t h a t w e re c h o s e n f o r t h i s s t u d y a r e : ( 1 ) c r o s s l i n k d e n s i t y , ( 2 ) am ount o f c a r b o n b l a c k , ( 3 ) am o u n t o f o i l , an d (I4 .) d e g r e e o f s t r a i n . T h ese p a r t i c u l a r v a r i a b l e s w e re c h o s e n b e c a u s e t h e y a r e o n e s t h a t c a n b e r e a d i l y r e g u l a t e d f o r c o n d i t i o n s o f a c t u a l s e r v i c e . TABLE 1 MATERIALS SYSTEM SBR l£ 0 0 1 0 0 .0 Z in c O x id e 5 .0 0 S t e a r i c A c id 1 .5 0 HAP B la c k V a r ia b l e C i r c o s o l ITS V a r i a b l e CBS ( S a n to c u r e ) V a r ia b l e S u l f u r V a r ia b l e The o r i g i n a l r e s e a r c h p l a n i n c l u d e d o z o n e c o n c e n t r a t i o n a s a v a r i a b l e . H o w ev er, d i f f i c u l t i e s e n c o u n te r e d i n f i n d i n g a r a n g e o f o z o n e c o n c e n t r a t i o n s t h a t w o u ld g iv e a n o v e r l a p o f d a t a , w h ic h i s so v i t a l t o a s t a t i s t i c a l s t u d y o f t h i s t y p e , m ade d e l e t i o n o f t h i s v a r i a b l e n e c e s s a r y . A n o th e r v a r i a b l e t h a t w as o m it t e d fro m t h e p ro g ra m w as t h e am ount o f a n t i o z o n a n t . T h is w as l e f t o u t b e c a u s e i t w as th o u g h t t h a t t h e a n t i o z o n a n t m ig h t i n t e r f e r e w i t h t h e c u r e s y s te m an d u p s e t th e a ssu m e d in d e p e n d e n c e o f c r o s s - l i n k d e n s i t y fro m b l a c k an d o i l . The e x p e r i m e n t a l d e s i g n s e l e c t e d f o r t h i s p ro b le m i s c a l l e d a c e n t r a l c o m p o s ite d e s i g n i n f o u r v a r i a b l e s ( B e f . 5 ) . T h is p a r t i c u l a r d e s i g n w as c h o s e n b e c a u s e i t w as s u s p e c t e d t h a t t h e e f f e c t s o f t h e f o u r i n d e p e n d e n t v a r i a b l e s o n o z o n e c r a c k i n g w o u ld b e n o n - l i n e a r . A r e q u ir e m e n t o f t h i s ty p e o f d e s i g n i s t h a t a l l i n d e p e n d e n t v a r i a b l e s p e r m i t a s e l e c t i o n o f e q u a l l y s p a c e d l e v e l s . The s e l e c t e d l e v e l s f o r e a c h o f t h e f o u r v a r i a b l e s a r e show n i n T a b le 2 . TABLE 2: LEVELS OP DEPENDENT VARIABLES dx l*» % B la c k , Xg O i l , S t r a i n , Xj^ 3 .2 3 20 p h r 0 p h r 20* 3 .8 0 3 5 5 l 5 $ ii-.37 50 10 20$ i . 9 i 6 5 15 .2 3 * 5 . 5 i 80 20 30$ '"’ C r o s s - l i n k D e n s i t y - c r o s s - l i n k s p e r gram x 1 0 " ^ T he c r o s s - l i n k d e n s i t y ( B ^ ) i s g o v e rn e d b y t h e am ount o f 5 i * i i s u l f u r an d a c c e l e r a t o r i n t h e e l a s t o m e r , b u t i t i s n o t a s im p le l i n e a r f u n c t i o n o f t h e i r c o n t e n t . T a b le 3 g i v e s ^ t h e am o u n ts o f s u l f u r an d a c c e l e r a t o r (CBS) t h a t w e re u s e d ; i n t h i s s t u d y t o g i v e t h e c r o s s - l i n k d e n s i t i e s i n T a b le 2 ' ( R e f . 1 7 ) . I TABLE 3 EQUALLY SPACED CROSS-LINK DENSITIES d XL CBS S u l f u r 3 .2 3 0 .7 0 p h r 1 .2 6 p h r 3 .8 0 0 .8 3 1 .5 3 2j.#37 0 .9 7 1 .8 3 If. 9 1 * . l . l i j . 2 .1 8 5 .5 1 1 .3 0 2 .5 2 A l i s t o f a l l o f t h e c o n d i t i o n s o r r u n s t h a t w e re c a r r i e d o u t i n t h i s p ro g ra m i s g i v e n i n T a b le ij. l a b e l e d E x p e r im e n ta l D e s ig n M a t r i x . B e c a u s e o f t h e l i m i t e d s i z e o f t h e o z o n e c h a m b e r, i t b ecam e n e c e s s a r y t o d i v i d e t h e d e s i g n m a t r i x i n t o s i x g ro u p s o f r u n s and p e r f o r m t h e e n t i r e s e r i e s o f m e a s u re m e n ts on o n e g ro u p a t a t i m e . T he m a t r i x w as d i v i d e d i n t h e f o l l o w i n g m a n n e r: Group No. Sun N os. 1 1 9 , 2 0 , 2 3 , 2 k , 2$ 2 17, 18, 21, 22, 26 3 1 , 3 , 5 , 7 , 27 k 2 , k» 8* 28 5 9 , 1 1 , 1 3 , 1 5 , 29 6 10, 12, I k , 16, 3 0, 31 TABLE 4 EXPERIMENTAL DESIGN MATRIX 6 i dXL'*» X1 Run N o. CBS S u l f u r B la c k , X2 O i l , x 3 S t r a i n , 1 0 .8 3 p h r 1 .5 3 p h r 33 P h r 5 p h r 15$ 2 1 .1 4 2 ,1 8 35 5 15 3 0 .8 3 1 .5 3 65 5 15 4 1 .1 4 2 .1 8 6 5 5 15 5 0 .8 3 1 .5 3 35 15 15 6 1 .1 4 2 .1 8 35 15 3.5 7 0 .8 3 1 .5 3 65 15 15 8 1 .1 4 2 .1 8 65 15 1 5 9 0 .8 3 1 .5 3 35 5 25 10 1 .1 4 2 .1 8 35 5 25 11 0 .8 3 1 .5 3 65 ’5 25 12 l . l k 2 .1 8 65 5 25 13 0 .8 3 1 .5 3 35 15 2 5 i t 1 . 1 11. 2 .1 8 35 15 25 1 5 0 .8 3 1 .5 3 65 15 25 16 1 .1 4 2 .1 8 65 15 25 17 0 .7 0 1 .2 6 50 10 20 18 1 .3 0 2 .5 2 5o 10 20 19 0 .9 7 I .8 3 20 10 20 20 0 .9 7 1 .8 3 80 10 20 21 0 .9 7 I .8 3 50 0 20 22 0 .9 7 1 .8 3 50 20 20 23 0 .9 7 1 .8 3 50 10 10 2 4 0 .9 7 1 .8 3 50 10 30 2 5 0 .9 7 1 .8 3 50 10 20 26 0 .9 7 1 .8 3 50 10 20 27 0 .9 7 1 .8 3 50 10 20 28 0 .9 7 1 .8 3 50 10 20 29 0 .9 7 1 .8 3 50 10 20 30 0 .9 7 1 .8 3 50 10 20 31 0 .9 7 1 .8 3 50 10 20 7 I t w i l l be n o tic e d th a t th e l a s t sev en runs in th e I jd esig n m atrix a re i d e n t i c a l . These runs serv ed a tw ofold j purpose in t h i s stu d y . The prim ary purpose was to show , any b a s ic e r ro r s o f measurement w hich were p r e s e n t. The secondary o b je c t iv e o f th e s e runs was to p ro v id e a c o n tr o l run f o r each o f th e s i x groups o f r u n s. They serv ed as in d ic a t o r s fo r any major u p se t in exp erim en tal c o n d itio n s . I Measured R esponses There are many tech n iq u es re p o rted in th e l i t e r a tu r e f o r a ssessm en t o f th e d eg ra d a tio n o f an ela sto m er due to ozone a tta c k ; how ever, a q uick rev iew o f th e s e te c h - f n iq u es w i l l show th a t many o f them are q u a lit a t iv e in n a tu r e . One o f th e requ irem en ts fo r a s t a t i s t i c a l stu d y o f t h is ty p e i s th a t th e measured re sp o n se s (dependent I !v a r ia b le s ) must be q u a n t it a t iv e . The re sp o n ses th a t were i |ch o sen f o r t h is stu d y a re as fo llo w s : (A) th e s e v e r it y o f •ozone cr a ck in g , (SQC)max, (B) th e d egree o f creep under ! c o n sta n t lo a d , and '(C) th e w craek volum e• ,r ' The B O G method i s a sim p le q u a n tita tiv e tech n iq u e d e v ise d by Vjpith ( l e f . Uj.) th a t a s s e s s e s th e d eg ra d a tio n by m easuring th e crack s i z e , a product o f th e average j ! ; le n g th and w id th . The sam ple th a t i s b ein g t e s t e d i s put in t o a s t a t e o f s t r a in and th e su r fa c e i s examined w ith a i i ,h ig h power m icroscop e c o n ta in in g a graduated r e t i c l e in I t h e e y e p i e c e . Any m a g n i f i c a t i o n may b e u s e d i n t h e m ea s u r e m e n t, b u t t h e v a l u e s a r e r e p o r t e d o n a l £ x b a s i s . I n t h i s s t u d y s i x o f t h e l a r g e r c r a c k s i n t h e u p p e r 10 t o 20 p e r c e n t o f t h e d i s t r i b u t i o n o f c r a c k s i z e s w e re s e l e c t e d f o r m e a s u re m e n t. When t h e c r a c k s i n t h e u p p e r p a r t o f th e c r a c k s i z e d i s t r i b u t i o n a r e c h o s e n , t h e SOG v a l u e i s r e f e r r e d t o a s t h e maximum SOG, (S 0C )ma3;. The c r e e p m e a s u re m e n t i s a n o t h e r m e th o d c o n t r i v e d by V e i t h ( R e f . 1$ ) . I n t h i s m eth o d t h e d e g r e e o f d e g r a d a t i o n i s d e te r m in e d q u a n t i t a t i v e l y b y h a n g in g w e ig h ts fro m t h e e l a s t o m e r s a m p le s an d m e a s u r in g t h e p e r c e n t i n c r e a s e i n e l o n g a t i o n u n d e r c o n d i t i o n s o f c o n s t a n t l o a d . T he t h i r d m e a s u re d r e s p o n s e , t h e ’’c r a c k v o lu m e ,” w as m e a s u re d b y a t e c h n iq u e d e v is e d b y S c h a e f ( R e f . 1 3 )* T h is m e th o d r e l a t e s t h e t h i c k n e s s i n c r e a s e o f a sa m p le u n d e r a c e r t a i n I n i t i a l s t r a i n to t h e v o lu m e c h a n g e d u e t o o z o n e c r a c k i n g . The M c r a c k v o lu m e 1 ’ I s c a l c u l a t e d b y u s e o f t h e f o l l o w i n g e q u a tio n :- ( h g - h - ,) 2 Vc = 2(112-1^) + e j ----- w h e re _ 2 Vc = ’’c r a c k v o lu m e ” e x p r e s s e d i n i n . / i n . o r t h e v o lu m e c h a n g e p e r u n i t a r e a d u e t o o z o n e c r a c k i n g h*L = o r i g i n a l t h i c k n e s s o f t h e s a m p le i n i t s e l o n g a t e d s t a t e h g = t h e t h i c k n e s s a f t e r c r a c k i n g h a s ta k e n p l a c e j EXPERIMENTAL PROCEDURE S am p le P r e p a r a t i o n : M ix in g i A l l m ix in g f o r t h i s s tu d y w as d o n e on a 6 x 12 i n c h l a b o r a t o r y r o l l m i l l . The b a tc h e s 'w ere a l l m ix e d o n t h e i i b a s i s o f i+O O g ram s o f e l a s t o m e r . The m ix in g tim e c y c l e s | recom m ended i n ASTM Dl£-5>9T w e re f o llo w e d a s c l o s e l y a s p o s s i b l e ; h o w e v e r, a fe w m o d i f i c a t i o n s h a d t o b e m ade d e - ‘ p e n d in g o n t h e a m o u n ts o f o i l a n d b l a c k u s e d . C o o lin g w a t e r w as p a s s e d th r o u g h t h e r o l l s a t a maximum r a t e a t a l l t i m e s ; an d t h e r o l l t e m p e r a t u r e s , m e a s u re d b y a s u r f a c e p y r o m e te r , w e re m a i n t a i n e d a t 120 + l 5 ° F , w h ic h i s s l i g h t l y d i f f e r e n t fro m t h e ASTM recom m ended 122 + 9 ° F . C u r in g T e n s i l e s h e e t s fro m t h e m ix e d b a t c h e s w e re c u re d i n . a s te a m p r e s s a t 3 0 7 °F an d 2100 p s i p l a t e n p r e s s u r e . A f t e r c u r i n g , t h e t e n s i l e s h e e t s w e re im m e d ia te ly p l a c e d i n c o ld w a t e r a n d a llo w e d t o c o o l f o r a t l e a s t t e n m in u t e s . T h ey w e re t h e n d r i e d an d p l a c e d b e tw e e n p a p e r to w e ls u n t i l r e a d y f o r u s e . F r e s h b a t c h e s w e re a lw a y s p r e p a r e d p r i o r t o a new g ro u p o f r u n s b e in g s t a r t e d , a n d t h e s a m p le s w e re p l a c e d i n t h e o z o n e c h am b er w i t h i n J2 h o u r s a f t e r th e c u r i n g o f t h e t e n s i l e s h e e t s . 10 I T e s t i n g o f P h y s i c a l P r o p e r t i e s A l l t e s t i n g o f p h y s i c a l p r o p e r t i e s , f o r t h e p u r p o s e o f d e te r m i n i n g optim um c u r e t i m e s , w as d o n e o n a t a b l e m o d e l I n s t r o n T e s te r * T he t e s t s w e re c a r r i e d o u t a c c o r d - i n g t o th e s p e c i f i c a t i o n s g iv e n i n ASTM D-J4 .I 2 . ' P r e l i m i n a r y W ork B e f o re t h e s t a t i s t i c a l s tu d y w as i n i t i a t e d , a s e r - ; i e s o f p r e l i m i n a r y r u n s w as m ade f o l l o w i n g t h e p r o c e d u r e s f o r m ix in g , c u r i n g , a n d t e s t i n g o f p h y s i c a l p r o p e r t i e s o u t l i n e d a b o v e . By c o m p le tio n o f t h e s e p r e l i m i n a r y r u n s , a s s u r a n c e w as o b t a i n e d t h a t t h e p h y s i c a l p r o p e r t i e s c o u ld . b e d u p l i c a t e d w i t h a r e a s o n a b l e d e g r e e o f a c c u r a c y . O zone T i t r a t i o n T he e n t i r e s t a t i s t i c a l s t u d y w as c a r r i e d o u t i n a n OREO 0300 o z o n e t e s t c h a m b e r. The c o n c e n t r a t i o n o f o z o n e i n t h e ch am b er w as d e te r m in e d b y a t i t r a t i o n m e th o d p r o p o s e d b y W a d e lin ( R e f . 1 8 ) . A s o l u t i o n co m posed o f one g ram p o ta s s iu m i o d i d e , f i v e m i l l i l i t e r s o f a p p r o x im a te ly 0 . 001N so d iu m t h i o s u l f a t e , and 70 m i l l i l i t e r s b u f f e r ( 1 . 8g Na2HP0^ a n d l . ? g KH2P0j^ p e r l i t e r ) w as d i v i d e d among a s e r i e s o f t h r e e i m p i n g e r s , and o z o n iz e d a i r fro m th e c h am b er w as d ra w n th r o u g h t h e s o l u t i o n a t a know n flo w r a t e f o r a m e a s u re d p e r i o d o f t i m e . T he r e a c t a n t s o l u t i o n w as th e n t r a n s f e r r e d to a b e a k e r , a c i d i f i e d w i t h t e n m i l l i l i t e r s o f 2M H 2S0^ , an d t i t r a t e d w i t h 0 . 0 0 1 0 0 N p o t a s - ' slu m i o d a t e t o a p o t e n t i o m e t r i c en d p o i n t* T he c h e m ic a l I ,r e a c t i o n s t h a t o c c u r b o t h d u r i n g im p in g e m e n t a n d t i t r a t i o n 1 a re :; * Impingement ' O3 4 * 2 1 “ + H20 * I 2 + 02 -f- 20H” i I 2 + 2S 20 3= = S^Ocf2 + 2 1 “ T i t r a t i o n I 0 3 “ +• $ T + 6 H+ » 3 i 2 + 3H20 I 2 + 2S 202~ — * * * 2 1 “ An i d e n t i c a l p r o c e d u r e w as f o llo w e d f o r a s e c o n d s o l u t i o n w i t h t h e e x c e p t i o n t h a t no o z o n iz e d a i r w as d ra w n t h r o u g h t h e i m p i n g e r s . P rom t h e d i f f e r e n c e o f t h e s e tw o t i t r a t i o n s , t h e o z o n e c o n c e n t r a t i o n w as d e te r m in e d b y u s e o f t h e f o l l o w i n g e q u a tio n :: 7 « CA-B) (K) (3 1 * 2 ) (T ) (lO ^ ) PPt w h e re Z = o z o n e c o n c e n t r a t i o n (pphm by v o lu m e ) A = m l. o f KIO3 u s e d i n t i t r a t i o n o f b la n k B = m l. o f KIO3 u s e d i n t i t r a t i o n o f sa m p le N = n o r m a l i t y o f KIO3 s o l u t i o n ( 0 . 0 0 1 0 0 H) T = t e m p e r a t u r e o f g a s , °K P = p r e s s u r e i n ram Hg 1 2 ; P = g a s f lo w r a t e , l i t e r / m i n . (1 *01). l i t e r / m i n . ) ! t = s a m p lin g t i m e , m in u te s (2 0 m i n . ) The o z o n e c o n c e n t r a t i o n w as h e l d a t $0 pphm t h r o u g h o u t t h e ! s t u d y ; and a f t e r th e c h am b er w as s e t a t t h i s c o n c e n t r a t i o n , c h e c k s w e re m ade a b o u t o n c e e v e r y two w e ek s t o i n - j I s u r e i t s c o n s t a n c y . The te m p e r a t u r e o f t h e ch am b er w as I m a i n t a i n e d a t 100 ± 2 ° P . i O zone C r a c k in g T e s t s D u m b b e ll s a m p le s ( c u t w i t h ASTM s t a n d a r d d i e 0) w e re s t a p l e d t o a p i e c e o f p a i n t e d p ly w o o d i n s u c h a m an n e r a s t o m a i n t a i n a c o n s t a n t e l o n g a t i o n t h r o u g h o u t th e t e s t . T he s a m p le s w e re e l o n g a t e d t o i n i t i a l s t r a i n s o f 1 0 , 1 5 , 2 0 , 2 5 , a n d 30 p e r c e n t . M e a s u re m e n ts w ere t a k e n a t i n t e r v a l s o f 2if. h o u r s f o r a p e r i o d o f f i v e d a y s . The c r a c k s w e re m e a s u re d w i t h t h e a i d o f a h i g h p o w e r b in o c u l a r m ic r o s c o p e c o n t a i n i n g a g r a d u a t e d r e t i c l e i n o n e e y e p i e c e . The l e n g t h o f t h e c r a c k s w as m e a s u re d a t llp c and t h e w id th a t i+Ox m a g n i f i c a t i o n . C re e p T e s t One i m p o r t a n t m o d i f i c a t i o n w as m ade i n t h e m e th o d em p lo y ed f o r p r e v i o u s s t u d i e s . A s m a ll d u m b b e ll (2^- i n . lo n g an d l / 8 i n . w id e a t n a r r o w p o r t i o n ) w as u s e d i n s t e a d 13 o f t h e p r e v i o u s l y u s e d T -5 0 s a m p le s . T h i s w as d o n e i n o r d e r t o p r e v e n t t h e p r e m a tu r e b r e a k i n g w h ic h so m e tim e s o c c u r s a t t h e c o r n e r s o n t h e T -5 0 s a m p le s . The d u m b b e ll s a m p le s w ere p r e p a r e d and w e ig h ts w e re h u n g fro m th em t o g i v e a c e r t a i n i n i t i a l s t r a i n . T hey w e re t h e n a llo w e d t o h a n g f o r a n o v e r n i g h t p e r i o d i n an o z o n e - f r e e e n v ir o n m e n t, an d t h e w e ig h ts w e re r e a d j u s t e d to g iv e t h e d e s i r e d i n i t i a l e l o n g a t i o n ( 1 0 , l 5 > 2 0 , 2 5 , o r 30 p e r c e n t ) . T h is p r o c e d u r e w as f o l lo w e d t o r e d u c e t h e c r e e p d u e t o v i s c o e l a s t i c b e h a v i o r t o a m inim um . The s a m p le s w e re th e n p l a c e d i n t h e o z o n e c h a m b e r, an d th e am ount o f c r e e p w as m e a s u re d w i t h a c a t h e t o m e t e r a t i n t e r v a l s o f s i x h o u r s f o r two d a y s . C r a c k Volum e D u m b b e ll s a m p le s ( c u t w i t h ASTM s t a n d a r d d i e € ) w e re p r e p a r e d an d p l a c e d i n a n a d j u s t a b l e fra m e an d s t r e t c h e d t o a n i n i t i a l s t r a i n o f 1 0 , l 5 > 2 0 , 2 5 , o r 30 p e r c e n t . T h ey w e re t h e n p l a c e d i n a n o z o n e - f r e e e n v i r o n m en t f o r a p e r i o d o f 16 h o u r s f o r a r e l a x a t i o n p e r i o d . The s a m p le s w e re t h e n p l a c e d i n t h e t e s t c h a m b e r. I n i t i a l t h i c k n e s s m e a s u re m e n ts an d t h o s e a t i n t e r v a l s o f s i x h o u r s f o r a p e r i o d o f two d a y s w e re m ade w i t h a d i a l m ic r o m e te r c a l i b r a t e d i n 1 x 1 0 "^- i n c h . ANALYTICAL PROCEDURE The o b j e c t i v e o f t h i s s t u d y i s t o p r o v i d e an e m p i r i c a l p r e d i c t i o n e q u a t i o n t h a t r e l a t e s a n y o f t h e m e a s u re d d e p e n d e n t v a r i a b l e s ( S0 G)max> c r e e p , an d c r a c k vo lu m e t o t h e f o u r i n d e p e n d e n t v a r i a b l e s ( c r o s s - l i n k d e n s i t y , am ount o f b l a c k , am ount o f o i l , a n d e l o n g a t i o n ) • A com p l e t e a n d d e t a i l e d a c c o u n t o f t h e m e c h a n ic s in v o lv e d i n d e v e lo p in g s u c h a n e q u a t i o n i s b e y o n d t h e s c o p e o f t h i s p a p e r , b u t a b r i e f e x p l a n a t i o n c a n b e i n c l u d e d t o p e r m i t a g r a s p o f t h e e le m e n ta r y i d e a s . T he m e th o d i n v o lv e d i n p r e d i c t i n g t h e e q u a t i o n i s s i m i l a r t o a c u rv e f i t t i n g o p e r a t i o n . I t i s s u s p e c t e d t h a t a p o ly n o m in a l e q u a t i o n c o n t a i n i n g u p t o s e c o n d o r d e r te rm s w i l l a p p r o x im a te t h e t r u e e q u a t i o n i n t h e r a n g e u n d e r c o n s i d e r a t i o n . T he e q u a t i o n t h a t r e l a t e s t h e d e p e n d e n t v a r i a b l e y t o t h e i n d e p e n d e n t v a r i a b l e s , x-^ t o x ^ , i s a s f o l l o w s :: L i n e a r S q u a re G r o s s - P r o d u c t I I o' o ■ f b i x i + b l l x l 2 + h 12x l x 2 + b 23x 2x 3 b 2x 2 + b 22x 22 + b 13x 1x 3 + b 2J+ x 2x 3 + b3x 3 + b33x 3 2 + b U,.x l ^ + b 31).x 33 ir lt + \ \ + b. , x. ^ e q u a t i o n c o n t a i n s - one c o n s t a n t te r m (b Q) * f o u r l i n e a r 1 5 c o e f f i c i e n t s ("fc^ to b j^ ), f o u r c o e f f i c i e n t s w hich, d e p i c t . s e c o n d o r d e r e f f e c t s C t>n t o b f ^ ) , a n d s i x c r o s s - p r o d u c t c o e f f i c i e n t s w h ic h show t h e i n f l u e n c e o f o n e v a r i a b l e o n t h e o t h e r (b-j^ to b ^ ) . j The c o e f f i c i e n t s a r e e v a l u a t e d b y th e m e th o d o f i ; m u l t i p l e r e g r e s s i o n ; an d i n o r d e r t o a v o id t h e t im e - c o n - js u m in g h a n d c a l c u l a t i o n s a s s o c i a t e d w i t h t h e m e th o d , t h e l v a l u e s o f x-^ t o x ^ a r e c o d e d i n t o a new s c a l e o f v a l u e s . The f o l l o w i n g t a b l e c o m p a re s t h e new c o d e d u n i t s t o t h e a c t u a l u n i t s . TABLE 5 DEPENDENT VARIABLES IN CODED UNITS C oded U n i t s C r o s s - l i n k D e n s i t y , X^ CBS S u l f u r B la c k , X2 O i l , X3 S t r a i n , X^ - 2 0 .? 0 p h r 1 .2 6 p h r 20 p h r 0 p h r 10 % - 1 0 .8 3 1 .5 3 35 5 15 0 0 .9 7 1 .8 3 50 10 20 1 1 .2 4 2 .1 8 65 15 25 2 1 .3 0 2 .5 2 80 20 30 The s o l u t i o n f o r t h e v a r i o u s b c o e f f i c i e n t s i s o b t a i n e d fro m t h e m e a s u re d y v a l u e s an d a n a r r a y o f nu m b ers c a l l e d t h e m a t r i x o f in d e p e n d e n t v a r i a b l e s ( T a b le 6 ) . T h is m a t r i x i s d e r i v e d fro m t h e e x p e r i m e n t a l d e s i g n m a t r i x w h ic h i s a l i s t o f t h e e x p e r i m e n t a l r u n s l i s t i n g t h e in d e p e n d e n t N O H c n H v O < 5 H K $ W P h H H p c , O H E H C M .<n N C M C M X C M H M -P ctf s b d •H C O © n C f\ S * ! C M X i — i X H H H H H H H H H H H H H H H H OO O O i^-shO OO OOOOO O H H H H H H H H H H H H H H H O O O O O O O O O O O O O H H H H H H H H H H H H H H H H - ^ - ^ h O O O O O O O O O O O O O H H H H H H H H H H H H H H I I I t I 111 HOOOO OOCMCMo OOOOO O I H H H H H H H H H H H H H H H H O O O O CM CM O O O O O O O O O I I I I till I H H H H H H H H H H H H H H H H O O CM CM O O O O O O O O O O O I i ii ti ii l H H H H H H H H H H H H H H H HCvJCMOO O O O O O OOOOO O I I I I I I I I I H H H H H H H H H H i I i 1 1—1 1—1 H H H H H H H r-1 1— I H r~l H H H H t—I i*i H CM H k -d " L f\ vO O-CO O ' O H C M C'-CO O ' O H C M v£> C —CO O ' O H H H H H H H H H H H C M CM CM CM CM CM CM CM CM CM CO TABLE 6 (c o n * t .) 1? lun x4 2 XiX2 x xx 3 % x4 X2X3 X2X 4 X3X4 Y 1 l 1 1 1 1 1 1 Y1 2 l -1 -1 -1 1 1 1 % 3 l -1 1 1 -1 -1 1 *3 4 l 1 -1 -1 -1 -1 1 y4 5 l 1 -1 1 -1 1 -1 A 6 i -1 1 -1 -1 1 -1 Y6 7 l -1 -1 1 1 -1 -1 y7 8 l 1 1 -1 1 -1 -1 y 8 9 l 1 1 -1 1 -1 -1 y9 10 i -1 -1 1 1 -1 -1 Y10 11 l -1 1 -1 -1 1 -1 Y11 12 l 1 -1 1 -1 1 -1 y 12 13 l 1 -1 -1 -1 -1 1 Y 13 34 l -1 1 1 — 1 -1 1 Y 14 15 l -1 -1 -1 1 1 1 y i 5 16 l 1 1 1 1 1 1 y 16 17 0 0 0 0 0 0 0 y17 18 0 0 0 0 0 0 0 y 18 19 0 0 0 0 0 0 0 Y 19 20 0 0 0 0 0 0 0 Y20 21 0 0 0 0 0 0 0 y 21 22 0 0 0 0 0 0 0 Y22 23 4 0 0 0 0 0 0 y 23 24 4 0 0 0 0 0 0 y 24 25 0 0 0 0 0 0 0 y 25 26 0 0 0 0 0 0 0 y26 27 0 0 0 0 0 0 0 y27 28 0 0 0 0 0 0 0 y 28 29 0 0 0 0 0 0 0 y 29 30 0 0 0 0 0 0 0 y30 31 0 0 0 0 0 0 0 Y 31 18 v a r i a b l e s i n c o d e d u n i t s ( T a b le 5 ) • I t w i l l b e n o te d t h a t a co lu m n l a b e l e d x Q h a s b e e n a d d e d a s p a r t o f t h e d e s i g n m a t r i x . T h is q u a n t i t y i s c a l l e d a ’’dummy” v a r i a b l e a n d i s a s s o c i a t e d w i t h th e c o n s t a n t bo» The s o l u t i o n s f o r th e b c o e f f i c i e n t s a r e a s f o llo w s :: b G = 0 .1 4 2 8 5 7 (Oy) - 0 .0 3 5 7 1 4 £ C i i y ) \> ± - 0 .0 4 1 6 6 7 ( i y ) b i± « 0 .0 3 1 2 5 0 ( i i y ) + 0 .0 0 3 7 2 0 £ ( i i y ) - 0 .0 3 5 7 1 4 (Oy) b ± j = 0 .0 6 2 5 ( i j y ) w h e re (O y) = sum o f p r o d u c t s o f co lu m n x c w i t h co lu m n y ( T a b le 6 ) ( i y ) = sum o f p r o d u c t s o f co lu m n x -,, X g, x ~ , o r x. w i t h co lu m n y ( T a b le 6 ) ( i j y ) = sum o f p r o d u c t s o f co lu m n x ^ X j( x 1X2 » x ^ x -j, e t c . ) w i t h co lu m n y ( T a b le 6 ) ( i i y ) = sum o f p r o d u c t s o f co lu m n x-^2, X2 ^ , x ^ 2 , 01» x ^ , w i t h co lu m n y ( T a b le 6 ) O £ ( i i y ) = s t h e sum o f t h e p r o d u c t s o f t h e co lu m n s x ^ w i t h y , X2^ w i t h y , w i t h y , an d x ^ 2 w i t h y ( T a b le 6 ) I t c a n be s e e n t h a t t h e s o l u t i o n o f t h e e q u a t i o n i s e f f e c t e d b y n o t h i n g m ore t h a n r o u t i n e m u l t i p l i c a t i o n an d a d d i t i o n ; h o w e v e r, s i n c e m any s u c h c a l c u l a t i o n s w e re i n v o lv e d i n t h i s s t u d y , t h e s o l u t i o n s w e re a l l c a r r i e d o u t o n a n IBM 7 0 7 4 c o m p u te r . RESULTS AND DISCUSSION R e s u l t s o f E x p e r im e n ta l R uns T he b a s i c d a t a ( i . e . , t h e m e a s u re d r e s p o n s e s ) t h a t w e re g e n e r a t e d b y t h i s p ro g ra m a r e g i v e n i n A p p e n d ix I I . I n l o o k in g o v e r t h e s e d a t a , i t w as d e te r m in e d t h a t a n i n d i c a t i o n o f t h e e f f e c t o f tim e on t h e s e r e s p o n s e s c o u ld b e p r o v i d e d w i t h o u t u s i n g a l l o f th e d a t a . A v e ra g e v a l u e s o f t h e f o l l o w i n g m e a s u re d r e s p o n s e s ( d e p e n d e n t v a r i a b l e s ) w e re s u b m i tt e d t o t h e IBM 7 0 7 4 c o m p u te r f o r a n a l y s i s : (S 0C )max f o r 1 , 3 , a n d f? d a y s ( T a b le 7 ) ; c r e e p f o r 6 , 1 8 , an d 36 h o u r s ( T a b le 8 ) ; an d " c r a c k v o lu m e " f o r 6 , 1 2 , 24» 3 6 , an d 4 8 h o u r s ( T a b le 9 ) . The r e s u l t s f o r t h e t h r e e d e p e n d e n t v a r i a b l e s a t t h e v a r i o u s tim e i n t e r v a l s w e re a n a ly z e d a c c o r d i n g to th e m e th o d s o u t l i n e d u n d e r A n a l y t i c a l P r o c e d u r e a n d a r e g iv e n i n T a b le s 1 0 , 1 1 , an d 1 2 . T h e se t a b l e s l i s t t h e v a l u e s o f t h e c o e f f i c i e n t s i n t h e e m p i r i c a l e q u a t i o n s r e l a t i n g e a c h o f t h e d e p e n d e n t v a r i a b l e s to t h e in d e p e n d e n t v a r i a b l e s . The c o e f f i c i e n t s a r e d i v i d e d i n t o t h r e e g r o u p s : t h e l i n e a r e f f e c t s b -j_ t o b ^ , t h e s e c o n d o r d e r ( c u r v a t u r e ) e f f e c t s b-j^ t o b) ^ , an d t h e i n t e r a c t i o n e f f e c t s b - ^ t o * > 3^* I n g e n e r a l i t c a n b e s a i d t h a t t h e a p p ro x im a te m ag n i t u d e o f t h e i n f l u e n c e o f a n y s i n g l e in d e p e n d e n t v a r i a b l e 20 TABLE 7 \ AVERAGE (S 0C )m g Q C VALUES ( R e p o r te d i n r e t i c l e u n i t s o n a l 5 x b a s i s ) Rim N o. 1 B ay 3 D ays 5 D ays 1 1 8 .7 lp9.9 7 k . 3 2 9 .k 3 3 .k 5 8 .5 3 9 .3 2 6 .1 k-8.9 k I{..6 2 3 .2 k 5 .7 5 1 2 .5 ij-5.8 7 3 .7 6 1 3 .3 k 2 .2 6 k . 2 7 1 9 .7 3 9 .5 5 0 .3 8 6 .8 2 7 .8 5 7 .3 9 9 .5 5 5 .7 8 k . 1 10 4 .6 2 7 .0 6 2 .5 11 8 .7 3 6 .9 8 5 .8 12 5 .0 2 k -3 5 1 .6 13 i k . 7 6 5 .5 8 8 .8 i k 6 .6 k O .l 7 5 .1 15 6 »k Ip .. 7 7 3 .8 16 2 .8 1 7 .8 k i . 5 17 7 .0 33*3 8 0 .6 18 k . 5 2 5 .1 5 5 .0 19 8 .0 1*6.5 9 0 . k 20 8 .1 31*-. 7 6 2 .0 21 5 .1 2 7 .9 5 3 .5 22 6 .6 k l . k 7 5 - k 23 1 2 .0 2 2 .8 3 9 .0 2k 2 .6 2 0 .0 6 1 .3 25 3 .6 3 1 .0 6 3 .1 26 5 .7 3 0 .9 6 5 .7 27 k*7 3 2 .9 6 5 .2 28 5 .6 3 3 .2 6 6 .6 29 6 .1 3 3 .0 6 1 .1 30 5 . 5 3 3 .2 6 k . 0 31 5 .3 3 2 .3 6 5 .7 21 TABLE 8 AVERAGE CREEP VALUES (R eported as per c e n t in c r e a se in le n g th ) Rim No. 6 Hours 18 Hours 38 Hours 1 1 .7 9 .2 2 6 .8 2 3 .7 9 .6 2 2 .0 3 3 .6 1 0 4 2 5 .8 4 2 .3 7 .1 1 9 .4 5 3 4 1 2 .7 3 5 .9 6 3 .0 8 .5 1 9 4 7 3 .9 1 2 .8 3 1 .9 8 2 .7 7 4 1 7 .8 9 7 .1 1 8 .2 3 6 .4 10 4 - 3 1 3 .0 2 8 .0 11 4*7 1 7 .0 4 3 .2 12 4 * 6 1 2 .0 2 6 .4 13 6 .8 1 8 .6 4 0 • 5 1 4 3 .9 1 1 .5 2 3 .9 15 6 4 1 4 4 3 0 .4 16 k .2 9 .9 1 9 .7 17 6 .0 1 7 .8 4 3 - 6 18 5 .2 1 1 .8 2 5 .6 19 5 .3 1 4 .7 4 3 .0 20 5 .1 1 1 .2 3 3 .5 21 7 .1 1 5 .6 3 2 .6 22 5 .8 1 2 .5 3 1 .6 23 1 4 6 . 2 2 0 .1 3 .1 1 0 .3 2 3 .0 25 4*7 1 1 .0 2 6 .4 26 5 4 1 2 .5 2 6 .9 27 4*3 1 2 .3 2 6 .0 28 3 .7 1 0 .3 2 5 .7 29 4 .9 1 2 .4 2 6 .5 30 3 .8 1 0 .8 2 6 .3 31 3 .9 1 1 .3 2 5 .8 22: I TABLE 9 AVERAGE CRACK VOLUME VALUES C lR eported i n i n . 3 / i n . ^ x 1 0 ^ ) Bun No. 6 H o u rs 12 H o u rs 24 H o u rs 36 H o u rs 4 8 H o u rs 1 1 5 .1 2 2 .2 3 4 .4 4 6 .8 5 7 . 2 2 l 4 * l 2 2 .2 3 5 * 5 4 4 .7 5 0 .9 3 1 4 .1 2 1 .2 3 8 .5 4 8 .9 6 0 .3 4 1 4 .1 2 4 .2 3 1 - 4 4 2 .7 4 8 .9 5 1 4 .1 2 1 .2 3 3 .4 4 2 .7 5 2 .0 6 1 1 .1 1 7 .1 2 9 .3 4 1 * 7 7 1 0 .0 2 4 .2 3 1 .4 4 0 .6 4 8 .8 8 9 . 0 1 4 .1 2 7 .3 3 3 .4 4 0 .6 9 2 7 .3 4 0 .6 6 7 .7 8 8 .9 1 0 0 .7 10 2 0 .2 4 3 .8 6 1 .4 7 0 .9 8 7 .8 11 3 5 .5 5 4 .1 8 2 .5 9 7 .4 1 1 0 .3 12 3 3 .4 5 9 .3 7 8 .2 9 1 .0 1 0 2 .7 13 3 1 .4 1*4.8 6 7 .8 8 5 .7 lfr 2 3 .3 4 0 .7 5 9 .3 7 2 .0 . 8 5 .8 15 3 0 .3 4 3 .8 6 5 .7 7 7 .2 8 7 .8 16 2 7 .3 4 3 .8 6 1 .4 7 3 .0 8 6 .8 17 2 2 .2 3 4 .5 5 3 .0 6 6 .6 7 6 .1 18 1 7 .3 2 9 .3 4 0 .6 5 4 - 1 65 *6 19 2 3 .3 3 3 .5 5 2 .1 6 4 .6 7 6 .2 20 2 7 .3 4 3 .7 6 3 .5 7 9 .2 9 5 .2 21 2 3 .2 3 7 .5 5 5 .1 6 8 .7 8 2 .3 22 2 0 .2 2 9 .4 4 9 .9 6 I .4 7 1 .9 23 1 3 .1 2 2 .2 3 2 .4 3 6 .5 4 1 .6 2 L } _ 2 6 .3 4 1 .7 6 1 .4 7 8 .3 9 3 .2 25 2 3 .2 3 5 .5 5 3 .1 6 0 .4 7 2 .0 26 2 2 .2 3 1 .4 4 8 .8 6 3 .4 7 8 .2 27 1 6 .1 3 0 .3 4 1 .7 5 5 .1 6 7 .6 28 1 8 .1 2 9 .3 4 3 .7 5 5 .1 6 7 .6 29 2 2 .2 3 1 .4 4 6 .8 6 0 .4 7 0 .8 30 1 9 .2 3 1 .4 4 6 .8 5 8 .3 7 0 .9 31 1 9 .2 3 2 .4 4 9 .9 6 4 .5 7 7 .1 23 TABLE 10 ANALYSIS OP DATA-COEFFICIENTS FOR (SOG)m ax PREDICTION ( R e p o r te d i n r e t i c l e u n i t s o n a l£ x b a s i s ) C o e f f i c i e n t V a r i a b l e 1 D ay 3 D ays 5 D ays *0 5 .2 * 32.1*.* 6If. 5* b l d XL - 2 . 1* - 5 .9 * - 7 .3 * b 2 HAF - 1 . 1* - 6 . 1* - 7 .6 * b 3 O i l 0 .6 7 3 .0 * 2 . If* bk S t r a i n - 2 .3 * 0 .6 5 5 • 6* b l l dx l ^ 0 .6 0 0 .1 8 0 . % b 22 HAF2 ■ 1 . 2* 3 .0 * 2 .9 * ^33 O i l 2 0 .6 3 1 .5 0 .0 1 hkb S t r a i n 2 0 .9 9 * - 1 .8 - 3 .6 b 12 x H AF - 0 .2 1 l.if. - 0 .1 3 b 13 ^XL x - 0 .0 8 -0.21}. 1 .6 b llf D ^ x S t r a i n 0 .3 6 - 3 .5 * — 5 • 0* b 23 HAF x O il 0 .2 0 - 0 .7 1 - 2 . 0 b 2i|. HAF x S t r a i n 0 .0 6 - 0 .8 1 0 .6 7 O i l x S t r a i n -O.JLj.8 - 0 .0 9 - i .i j . B2 0 .6 5 0 .7 9 0 .9 0 * S i g n i f i c a n t V a lu e s - S ee T - t e s t V a lu e s i n A p p e n d ix I I I . 2 k TABLE 11 ANALYSIS OP DATA-COEFFICIENTS FOR CREEP PREDICTION (R e p o rte d a s p e r c e n t i n c r e a s e i n l e n g t h ) C o e f f i c i e n t V a r i a b l e 6 H o u rs 18 H o u rs 36 H o u rs b0 k + k 3 * 1 1 .5 * 2 6 .2 * b l dx l -O.Lflj.* - 1 .9 * - 5 .if* b 2 HAF - 0 .0 8 - 0 . 72 * - 1 . 6* bo O i l — 0 #01 - 0 .2 9 -O.ljJj. bk S t r a i n 0 . 88* 1 .9 * 2 .3 * b l l % L 2 0 .1 8 0 .7 l|* 1 .5 * b 22 HAF2 0 .0 8 0 .2 8 2 .lf* b 33 O i l 2 0 .3 9 * 0 .5 5 * 0 .8 6 biA S t r a i n 2 - 0 . 66* - 0 .9 0 * - 1 . 8* b12 x HAF -O.Olj. - 0 .1 3 - 0 .1 1 b 13 % L x o i l - 0 .2 8 - 0 .5 1 - 1 .3 b lij. I>XL x S t r a i n -0 - 0 . 58 * -O .67 b 23 HAF x O i l 0 .1 1 - 0 .2 1 - 1 . 3 b2k HAF x S t r a i n - 0 .1 8 - 0 .3 6 0 .0 1 h3k O i l x S t r a i n - 0 . 0? - 0 . 68 * - 1 .9 * 2 R 0 .7 7 0 .9 0 0 .8 8 * S i g n i f i c a n t V a lu e s - S ee T - t e s t V a lu e s i n A p p e n d ix I I I . TABLE 12 ANALYSIS OP DATA-COEFFICIENTS FOR CRACK VOLUME PREDICTION (R e p o rte d a s i n . 3 / i n . 2 x 10k ) C o e f f i c i e n t V a r ia b le 6 Hours 12 Hours 2ij. Hours 3& Hours I 4 . 8 Hours u o *1 b2: b 3 \ b l l b22 b 33 V b12 bl3 b i 4 b 23 b 2 1 * . h3b H2 2 0 . 0* 3 1 .7 * 1 ; 7 . 0* 5 9 . 6* 7 2 . 0* % L - 1 .5 * - 0 .7 2 — 2 . 6* - 3 .5 * - 3 4 * HAF 1 .0 2 . 2* 2 .1 1 .7 1 .9 O il - 0 .9 7 - 2 .3 * - 2 .7 * - 3 .3 * - 3 .9 * S t r a i n 6 4 * 1 0 . 1* lii.. 2* 1 6 . 6* 1 8 .9 * s XLr - 0 .2 5 - 0 .0 1 - 0 .1 6 - 0 .0 3 - 0 .7 1 HAF2 1 . 2* 1 .7 * 2 . 6* 2 .9 * 3 .0 * O i l 2 0 .2 6 0 .3 8 1 .3 1 .1 0 .8 5 S t r a i n 2 -O .2I4 . O.OOlj. - 0 .1 3 - 0 .7 1 - 1 .6 D x l x HAF 0 .8 2 0 .1 9 - 0 .1 3 0 .6 8 0 .2 9 ^XL x - 0 .3 1 - 1 . 9 - 0 .2 8 0 4 1 0 .9 6 D ^ x S t r a i n - 0 .9 6 0 .9 7 - 0 .5 8 - 1 .6 -O .07 HAF x O il - 1 . 5 -1*7 - 2 .2 - 2 .9 - 2 .7 HAF x S t r a i n 2 .0 * •1 ,9 2 .2 2 .0 1 .7 O il x S t r a i n 0 .5 7 -O .7 2 - 1 .1 - 0 .9 8 - 1 .1 0 .8 8 0 .8 8 0 .8 8 0 .9 1 0 .9 3 * S i g n i f i c a n t V a lu e s - S ee T - t e s t V a lu e s i n A p p en d ix I I I 26 i s in d ic a te d by th e v a lu e o f i t s lin e a r c o e f f i c i e n t . Each c o e f f i c i e n t g iv e s th e amount th e dependent v a r ia b le changes per u n it (coded v a lu e) change in th e in depend en t v a r ia b le provided th e cu rvatu re i s s m a ll. Thus, fo r ex am ple, fo r a u n it in c r e a s e in th e degree o f s t r a in (%%), th e Bcrack volum e” (Vc ) a t s i x hours w i l l in c r e a s e by 6 * 4 x 10“^ - in * 3/ i n . ^ . I f th e cu rvatu re i s n o t sm a ll, as i s th e ca se fo r many o f th e r e s u lt s in t h is stu d y , then an a n a ly s is o f t h is ty p e i s n ot a llo w a b le . The second s e t o f c o e f f i c i e n t s in d ic a t e s th e magni tude o f th e cu rvatu re in th e r e la t io n s h ip betw een th e de pendent v a r ia b le ,a n d th e independent v a r ia b le s . In g en e r a l an upward cu rvatu re o f th e dependent v a r ia b le v s . each in dependent v a r ia b le (s e e F ig u res 1 to 11) i s in d ic a te d by a p o s it iv e c o e f f i c i e n t , and th e o p p o site i s tru e f o r a n e g a tiv e c o e f f i c i e n t . When th e m agnitude o f th e secon d - order c o e f f i c i e n t approaches th e m agnitude o f o r becomes la r g e r than th e lin e a r c o e f f i c i e n t , th e cu rvatu re may be so g r e a t a s to cause a p o in t o f i n f l e c t i o n , i . e . , a change in th e s ig n o f th e s lo p e . The th ir d s e t o f c o e f f i c i e n t s , th e c r o ss-p r o d u c t or in t e r a c t io n term s, are g e n e r a lly sm a ller in m agnitude than th e o th er c o e f f ic ie n t s * The c o e f f i c i e n t s w ith an a s t e r is k (T a b les 10, 1 1 , and 12) are th e c o e f f i c i e n t s th a t have s u f f i c i e n t m agni tude as to be co n sid ered s i g n i f i c a n t . T h is s ig n if ic a n c e ! 27 i ! I i !was determ ined w ith a t e s t known as th e t - t e s t . A d e s - i ,c r ip t io n o f th e t - t e s t i s beyond th e scope o f t h is paper, ;bu.t b a s ic a l ly i t i s a s t a t i s t i c a l t e s t o f th e s ig n if ic a n c e o f a s e t o f ex p erim en ta l or e m p ir ic a l d ata when th e " tru e” i standard d e v ia tio n o f th e p o p u la tio n i s unknown (R e f. 1 6) . ;As a g e n e r a l r u le o f thumb, a t v a lu e o f ap p roxim ately 2 ''(a b so lu te v a lu e) or g r e a te r sh ou ld be o b ta in ed in ord er to co n sid e r the c o e f f i c i e n t s s i g n i f i c a n t . The t - t e s t v a lu e s a s s o c ia te d w ith th e c o e f f i c i e n t s are l i s t e d in Appendix * ' I I I . A good method fo r d eterm in in g th e r e l a t i v e m agni tude o f th e e f f e c t s o f th e fo u r independent v a r ia b le s i s to r e c a lc u la t e each c o e f f i c i e n t as a p ercen ta g e o f th e bQ v a lu e . The c o e f f ic i e n t bQ i s th e v a lu e o f th e dependent v a r ia b le when a l l in dependent v a r ia b le s are at t h e ir m iddle l e v e l ( i . e . , 0 ); bQ i s th u s th e average o f a l l dependent v a lu e s or th e m iddle o f th e d e s ig n . The c o e f f i c i e n t v a lu e s th a t have been p la ced on t h i s r e l a t i v e b a s is are found in T ab les 13, lip, and 1^ . G raphical D isp la y o f R e s u lts A q u ick grasp o f the e f f e c t s o f th e fo u r in d ep en d en t v a r ia b le s may be o b ta in ed by r e fe r r in g to F ig u res 1 to 1 1. These have been co n str u c te d by c a lc u la tin g dependent v a r i a b le v a lu e s by means o f th e c o e f f i c i e n t s in T ab les 10, 11, and 1 2 . The p o in ts shown on th e s e cu rves are c a lc u la te d 28 TABLE 13 RELATIVE COEFFICIENTS FOR (SOC)m ax PREDICTION ( R e p o r te d a s a p e r c e n t a g e o f th e Lq v a l u e ) C o e f f i c i e n t V a r i a b l e b 0 b l % L b 2 HAF b 3 O il S t r a i n b l l D ^ dx l b 2 2 h a f2 > b 33 O i l b iO i- S t r a i n 2 b 12 D ^ x HAF b 13 D yjf 3 C O i l b iii. Djg^ x S t r a i n b 23 HAF x O il b 24 HAF x S t r a i n b 3ij- O i l x S t r a i n 1 D ay 3 D ay s 5 D ays 100 100 100 -lj.0 .0 - 1 8 .2 - 1 1 .3 - 2 1 .2 - 1 8 .8 . - 1 1 .8 1 2 .9 9 .3 3 - 7 -I} 4 .0 2 .0 8 .7 1 1 .5 0 .6 1 .3 2 3 .1 9 .3 1 2 .1 lj..6 — 1 9 .1 -5 * 6 - 5 . 6 -lj..0 k*3 - 0 . 2 - 1 . 5 - 0 .7 2 . 5 6 .9 - 1 0 .8 - 7 . 8 3 .8 - 2 . 2 - 3 . 1 1 .2 - 2 . 5 1 .0 - 9 . 2 - 0 .3 - 2 . 2 2 9 TABLE ll|* RELATIVE COEFFICIENTS FOR CREEP PREDICTION j (R eported aa a p ercen ta g e o f th e b© v a lu e ) ____________________________________________________________i C o e f f i c i e n t V a r i a b l e 6 H o u rs 18 H o u rs 36 H o u rs fe0 100 100 100 b l dxl -1 0 * 0 - 1 6 .5 - 2 0 .6 b 2 RAF - 1 . 8 - 6 . 3 - 6 . 1 b 3 O i l - 0 . 2 - 2 . 5 - 1 . 7 \ S t r a i n 2 0 .0 1 6 .5 8 .8 b l l DXL* 4 .1 5*6 5 . 7 b 22 HAF2 1 .8 2 * 4 9 . 2 b 33 O i l 2 8 .9 4 .8 3 .3 b 4 4 S t r a i n 2 - 1 5 . 0 - 7 . 8 - 6 . 9 b 1 2 P Y T > x HAF - 0 .9 - 1 . 1 - 0 * 4 b 13 ■^XL x ° * '1 ' - 6 .4 - 4*4 - 5 . 0 b l 4 ■^XL x s t r a ^ n - 1 0 . 0 - 5 . 1 - 2 . 6 ! 1 b 23 HAF x O il 2 . 5 - 1 . 8 - 5 . ° | b 2 4 HAF x S t r a i n - 4 . 1 - 3 . 1 — b 3 4 O il x S t r a i n - 1 . 7 - 5 . 9 - 7 . 3 1 1 i TABLE 15 RELATIVE COEFFICIENTS FOR CRACK VOLUME PREDICTION (R e p o rte d as a p e r c e n ta g e o f th e 1 dq v a lu e ) [• ic ie n t V a r ia b le 6 H ours 12 H ours 2 1 }. H ours 36 H ours if 8 Hou] b o 100 100 100 100 100 b l DXL - 7 4 -2 * 3 - 5 .5 -5 * 8 4 . 7 b 2 HAP 5 .0 6 .9 b S 2 .9 2 .6 b 3 O il 4 * 8 - 7 .3 - 5 .7 - 5 .5 - 5 4 \ S t r a i n 3 1 .7 3 1 .9 3 0 .2 2 7 .8 2 6 .3 b l l % L 2 - 1 .2 — ' - 0 .3 - 0 .1 - 1 .0 b 22 HAF^ 5 .9 5 4 5 .5 lf.9 i f . 2 b 33 O i l 2 1 .3 1 .2 2 .8 1 .8 1 .2 b4ir S t r a i n ^ - 1 .2 " w m - 0 .3 - 1 .3 - 2 .2 b 12 x HAF i f . l 0 .6 - 0 .3 1 .1 0 4 b 13 x O il - 1 .5 - 6 .0 - 0 .6 0 .7 1 .3 b llf x S t r a i n 4 . 8 3 .1 - 1 .2 - 2 .7 - 0 .1 b 23 HAP x O il - 7 4 - 5 4 4 . 7 4 . 9 - 3 .7 b 2lf HAP x S t r a i n 9 .9 6 .0 b - l 3 4 2 4 h3k O il x S t r a i n 2 .8 - 2 .3 - 2 .3 - 1 .6 - 1 .5 (S O C )M A X AFTER I DAY (RETICLE UNITS- 15X B A S IS ) OIL STRAIN IO 2 O -2 INDICATED X -V A R IA B L E FIGURE 1 (SOC) After 1 Day Vs. the Independent Variables max 1 (SO C)M A X AFTER 3 DAYS (RETICLE UNITS-I5X BASIS) G D x l A H A F 6 0 V S T R A IN 5 0 A O 3 0 20 -2 INDICATED X - V A R I A B L E FIGURE 2 (so c ) v max After 3 Days Vs. the Independent Variables (SOC)M A X AFTER 5 DAYS (RETICLE UNITS - I5X BASIS) i 33 O D x l A HAF 9 0 V STRAIN 8 0 T O 6 0 5 0 3 0 2 O -2 INDICATED X — VARIABLE FIGURE 5 (SOC) After 5 Days Vs. the Independent Variables max CREEP AFTER 6 HOURS(PERCENT INCREASE I N LENGTH) U U XL A HAF 6.0 V STRAIN 5 .0 3 .0 2.0 1 . 0 -2 INDICATED X-VARI A B L E FIG U RE 4 Creep After 6 Hours Vs. the Independent Variables CREEP AFTER 1 8 HOURS (PERCENT INCREASE I N LENGTH) 35 2 0 U XL HAF Ol L ST R A IN - 2 INDICATED X-VARI A B L E FIGURE 5 Creep After 18 Hours Vs. the Independent Variables CREEP AFTER 36 HOURS <PERCENT INCREASE I N LENGTH) 36 4 0 3 5 3 0 H A F ST R A IN 2 5 20 - 2 - I O I INDICATED X - V A R I A B L E FIGURE 6 Creep After 36 Hours Vs. the independent Variables CRACK VOLUME (Vc ) AFTER 6 HOURS( in3/ i n 2 X IO O d x l A H A F V ST R A IN 2 5 20 2 O -2 INDICATED X — VARIABLE FIGURE 7 Crack Volume After 6 Hours Vs. the Independent Variables CRACK VOLUME (Vc) AFTER 1 2 HOURS (in3/ i n 2 X IO 38 O DXl A HAF 6 0 V S T R A IN 5 0 4 0 3 0 20 IO 2 O - 2 INDICATED X -V A R I A B L E FIGURE 8 Crack Volume After 12 Hours Vs. the Independent Variables CRACK VOLUME (Vc ) AFTER 24 HOURS ( in3/ i n 2 X I O4 ) 3 9 ^ U XL A H A F TO V S T R A IN ©O 5 0 4 0 3 0 20 2 O 2 INDICATED X —VARI A B L E FIGURE 9 Crack Volume After 24 Hours Vs. the Independent Variables O D x l A HAF 80 V STRAIN O 60 50 30 20 2 O -2 INDICATED X— V A R IA B L E FIGURE 10 Crack Volume After 36 Hours Vs. the Independent Variables CRACK VOLUME (V c ) AFTER < 48 HOURS ( i n ° / i n i}.l ° X L HAF Ol L ST R A IN I 20 O X IO O S O S O 20 - 2 INDICATED X - V A R I A B L E FIGURE 11 Crack Volume After 48 Hours Vs. the Independent Variables k 2 i j p o i n t s . B a ch p l o t i s d ra w n w i t h t h e in d e p e n d e n t o r x - , v a r i a b l e g iv e n i n t h e c o d e d s c a l e o f u n i t s ( r e f e r t o T a b le ! 5 ) • F o r e a c h c u r v e th e v a lu e o f t h e o t h e r t h r e e x - v a r i - ] a b l e s i s h e l d a t t h e m id - o r z e r o l e v e l . T he p o i n t o f i | i n t e r s e c t i o n i s t h u s b Q. F i g u r e s 1 to 11 i l l u s t r a t e w h a t ! ; c a n b e i n f e r r e d fro m i n s p e c t i o n o f t h e b c o e f f i c i e n t s , s o I n o f u r t h e r d i s c u s s i o n i s n e c e s s a r y . i j D i s c u s s i o n o f B e s u l t s I By s c a n n in g t h e c o e f f i c i e n t s a n d t h e g r a p h s f o r | (SO C)m ax, c r e e p , a n d Vc , th e f o l l o w i n g g e n e r a l c o n c l u s i o n s i c a n b e d r a w n . The c r o s s - l i n k d e n s i t y (E>xi») an d th e am o u n t j o f HAF b l a c k h a v e t h e g r e a t e s t i n f l u e n c e on ( S 0 0 ) m ax, a n d t h e i r e f f e c t s te n d t o d e c r e a s e s l i g h t l y w i t h p r o lo n g e d e x - i • p o s u r e . By i n c r e a s i n g th e c r o s s - l i n k d e n s i t y , th e (SOG)max b eco m es s m a l l e r . T h is e f f e c t i s e s s e n t i a l l y l i n - | e a r . An i n c r e a s e d a m o u n t o f HAF b l a c k w i l l c a u s e a lo w e r ! | (S O C j^ ax u p t o a c e r t a i n maximum c o n c e n t r a t i o n ( a p p r o x i - | r a a te ly p h r . ) , b u t n o n - l i n e a r i t y i s o f s u f f i c i e n t m a g n i tu d e a s t o c a u s e a n o p p o s i t e e f f e c t b e y o n d t h i s c o n c e n t r a t i o n . i i T he e f f e c t o f s t r a i n i s n e x t i n l i n e i n im p o r t a n c e . An i n c r e a s e i n t h e d e g r e e o f s t r a i n w i l l c a u s e a n i n c r e a s e i n th e (SO C)ma:g u n t i l th e s t r a i n r e a c h e s a c e r t a i n maximum | (20$ to 2$%), a n d b e y o n d t h i s p o i n t a n i n c r e a s e i n t h e s t r a i n w i l l h a v e b e n e f i c i a l e f f e c t s . T h i s e f f e c t i s j u s t t h e o p p o s i t e f o r (SO C)^ a f t e r o n e d a y , b u t th e a g re e m e n t b e tw e e n t h e c a l c u l a t e d a n d e x p e r i m e n t a l r e s u l t s a t one d a y i s n o t g o o d . T h is c h a n g e o f e f f e c t i s d u e t o t h e n o n - j l i n e a r i t y o f t h e v a r i a b l e . The e f f e c t o f s t r a i n i n c r e a s e s i a s t h e e x p o s u r e i s e x te n d e d . The e f f e c t o f o i l on t h e (SGC)m ax i s e s s e n t i a l l y n i l . T he o n ly i n t e r a c t i o n e f f e c t ! t h a t a p p e a r s t o b e s i g n i f i c a n t f o r (SO C)T ns > T i s th e i n t e r a c t i o n b e tw e e n c r o s s - l i n k d e n s i t y a n d d e g r e e o f s t r a i n . |T h is e f f e e t t e n d s t o i n c r e a s e w i t h i n c r e a s e d e x p o s u r e 1( s e e T a b le 1 0 ) . j T he v a r i a b l e s t h a t h a v e t h e m o s t i n f l u e n c e on c r e e p a r e t h e d e g r e e o f s t r a i n a n d th e c r o s s - l i n k d e n s i t y . T he d e g r e e o f s t r a i n h a s th e g r e a t e s t e f f e c t a f t e r a s h o r t e x p o s u r e t i m e ; b u t a s th e e x p o s u r e i s l e n g t h e n e d , th e e f f e c t b e co m es s m a l l e r , a n d t h e c r o s s - l e n g t h d e n s i t y b eco m es i t h e m o st s i g n i f i c a n t . An i n c r e a s e i n t h e d e g r e e o f s t r a i n w i l l c a u s e t h e c r e e p t o i n c r e a s e u n t i l a c e r t a i n maximum s t r a i n i s r e a c h e d (2 0 $ t o 2f>$); b u t b e c a u s e o f t h e n o n - l i n e a r i t y , a n i n c r e a s e i n s t r a i n w i l l c a u s e a d e c r e a s e i n c r e e p b e y o n d t h i s p o i n t . I n c r e a s i n g t h e am o u n t o f c r o s s - l i n k a g e h a s th e e f f e c t o f lo w e r i n g t h e c r e e p ; a n d t h i s e f f e c t b e co m es g r e a t e r a s e x p o s u r e tim e p r o g r e s s e s . A g a in n o n - l i n e a r i t y i s i n d i c a t e d a n d t h e b e n e f i c i a l e f f e c t t e n d s t o l e v e l o f f a f t e r a c e r t a i n maximum c r o s s - l i n k d e n s i t y i s i kk I 'r e a c h e d ( c o d e d v a lu e o f a p p r o x i m a t e ly 1 - T a b le *>). T he e f f e c t o f HAF c o n c e n t r a t i o n on c r e e p i s n o n - I l i n e a r , a n d b o th t h e e f f e c t a n d th e n o n - l i n e a r i t y i n c r e a s e w i t h p r o lo n g e d e x p o s u r e . An i n c r e a s e d a m o u n t o f HAF w i l l I h a v e b e n e f i c i a l r e s u l t s u n t i l a c e r t a i n c o n c e n t r a t i o n i s * o b t a i n e d ( a p p r o x i m a t e l y $ 0 p h r . ) , a n d b e y o n d t h i s p o i n t t , th e e f f e c t b e g i n s t o l e v e l o f f a n d t h e n c h a n g e . An I n - i i j c r e a s e i n t h e c o n c e n t r a t i o n o f o i l h a s a s l i g h t e f f e c t o n t ; c r e e p . T h is e f f e c t i s a lm o s t e n t i r e l y d u e to th e s e c o n d - I i o r d e r t e m a n d te n d s to becom e s m a l l e r a s e x p o s u r e tim e i s ^ e x te n d e d . An i n c r e a s e d am o u n t o f o i l h a s th e e f f e c t o f I l o w e r i n g th e c r e e p u n t i l a c e r t a i n maximum i s r e a c h e d ( a p p r o x i m a t e l y 1© p h r . ) , a n d t h e n t h e e f f e c t r e v e r s e s . T he o n ly i n t e r a c t i o n r e s u l t s t h a t a p p e a r t o a f f e c t c r e e p a r e c r o s s - l i n k d e n s i t y w i t h s t r a i n a n d o i l w i t h s t r a i n . T he v a r i a b l e t h a t h a s b y f a r th e g r e a t e s t i n f l u e n c e ; on th e " c r a c k v o lu m e ” i s t h e d e g r e e o f s t r a i n . An i n - i c r e a s e i n th e d e g r e e o f s t r a i n w i l l c a u s e a n i n c r e a s e i n t jV c . The e f f e c t i s a lm o s t c o m p l e t e ly l i n e a r a n d i s e s s e n t i a l l y t h e same a t b o t h s h o r t a n d l o n g e x p o s u r e t i m e s . T he e f f e c t o f HAF c o n c e n t r a t i o n a p p e a r s to b e n e x t i n l i n e o f im p o r ta n c e w ith r e s p e c t t o Vc . I t s e f f e c t i s a lm o s t e n - 1 t i r e l y d u e t o t h e s e c o n d - o r d e r c o e f f i c i e n t . U n t i l a I c e r t a i n maximum c o n c e n t r a t i o n I s r e a c h e d , a n i n c r e a s e I n HAF w i l l c a u s e a d e c r e a s e i n Vc j b u t a f t e r t h i s I k$ I I I c o n c e n tr a tio n (a p p ro x im a tely 1|5 p h r * ), th e r e s u l t s are ; I ; : rev ersed * The e f f e c t s o f o i l and c r o s s -lin k a g e are o f I e s s e n t i a l l y th e same m agnitude and are m a in ly l i n e a r . An \ | ln ^ „ o n and . 0 oro8S- n n* den3lty ( | has the e f f e c t o f lo w erin g th e “cra ck v o lu m e.’ * The e f f e c t s . i i ! o f I n te r a c tio n on “crack volum e” are v ery s m a ll. ; i I « • ; j | C r it ic a l Comment t A lthough th e s t a t i s t i c a l tech n iq u e as b r ie f l y o u t lin e d in t h is paper i s q u ite e f f i c i e n t and econom ical o f <e f f o r t in in v e s t ig a t in g a r e l a t i v e l y com plex fo u r -v a r ia b le i ! problem su ch a s t h i s , i t i s n ot w ith o u t i t s d isa d v a n ta g e s. S in c e i t i s so e f f i c i e n t and com pact, each d ata p o in t or measured resp o n se c a r r ie s a g r e a te r w eig h t in c o n tr ib u tin g to th e f i n a l r e s u lt s ( c o e f f i c i e n t s in th e e q u a tio n s) than iin a l e s s w e ll-d e s ig n e d and l e s s e f f i c i e n t ex p erim en ta l 'd e s ig n . T h e r e fo r e , th e r e sh ou ld be some method fo r d e t e r - • .m ining th e v a l i d it y o f th e r e s u l t s . ' A t th e bottom o f th e columns o f c o e f f i c i e n t s |(T a b le s 10, 11, and 12) are l i s t e d v a lu e s fo r th e c o e f f i - j t c le n t o f d eterm in a tio n (R ) . T h is q u a n tity x 100 in d ic a te s th e amount o f t o t a l v a r ia tio n among a l l resp o n ses or d ata I jv a lu e s a s l i s t e d in T ab les 7 , 8 , and 9 th a t can be a c counted f o r by th e em p ir ic a l eq u a tio n w ith i t s c o e f f i c i e n t s la s l i s t e d in the column above i t . T h is i s a measure o f ij.6 th e o v e r a ll f i t o f th e eq u a tio n to th e ex p erim en ta l d a ta (E e f. 16) . In g e n e r a l, th e agreem ent betw een the ex p erim en ta l d ata f o r (SOC)max a f t e r 5 8a y s , creep a f t e r 18 and 36 h o u rs, and Ve a f t e r 6 , 12, 2I4., 3 6 , and I4 .8 hours i s f a i r . The c o e f f i c i e n t s o f d eterm in a tio n (R^) are in th e range o f 0.88 to 0.93 fo r th e se r e s u lt s j th ey should id e a ll y be in th e range o f 0.95 to O .9 9 . The agreem ent fo r (S0C)max a f t e r 1 and 3 days and fo r creep a f t e r 6 hours i s n o t good, P a rt o f th e la c k o f f i t i s p rob ab ly due to th e f a c t th a t J th e experim ent was run in s e v e r a l b lo c k s or groups o f | r u n s . A ny b l o c k - t o - b l o c k v a r i a t i o n w i l l d e c r e a s e t h e d e - | gree o f agreem ent due to s l i g h t b ia s e s in the measured r e s p o n s e s . O aution sh ould be e x e r c is e d when u s in g th e equa- 1t i o n s . The c a lc u la te d resp on se v a lu e s n ea r the o u ter r e g io n s o f th e ex p erim en ta l f a c t o r sp a c e , i . e . a t th e - 2 and \2 l e v e l s (cod ed u n i t s ) , w i l l be somewhat o f f a t X j_ v a lu e s o th e r than z e r o . T his i s due to th e low er v a lu e s . For exam ple, i f Y i s c a lc u la te d v s . a t X2 * * X^ - X^ 8 8 G from -2 to 2 0 , f a i r l y good agreem ent w i l l b e o b tain ed j betw een Y ( c a lc u la t e d ) and Y (m ea su red ). However, i f X~, X^, and X|^ a re s e t a t - 2 , 2 , and 2 , r e s p e c t iv e ly (a s an j exam ple) and Y i s c a lc u la te d vs* X-^, the r e s u lt s may be j s e r io u s ly o f f a t X^ 8 5 -2 and X -^ = 2 b u t a l l r ig h t a t - 1 , 0 , and 1 . S in c e th ere are no measured Y v a lu e s fo r com p a r iso n a t th e se l e v e l s , th e r e i s no way o f t e l l i n g th a t ;the v a lu e s are o f f u n le s s some n e g a tiv e Y v a lu e s are c a l - ie u la t e d . T h ese, o f c o u r se , are m ea n in g less and se r v e a s a i w a r n in g f l a g o f t h i s c o n d i t i o n * I f w ere 0 .9 8 t o 0*99* i t h i s w o u ld n o t o c c u r . I i SUMMARY AND CONCLUSIONS i Sum m ary T h is program was c a r r ie d out to d eterm in e the in - ! ; flu e n c e o f fo u r in depend en t v a r ia b le s on ozone © racking. ! |T h ese fo u r v a r ia b le s are c r o s s - lin k d e n s it y , c o n c e n tr a tio n t * ; o f carbon b la o k , c o n c e n tr a tio n o f o i l , and th e d egree o f i j s t r a in . The I n v e s t ig a t io n o f t h e ir in flu e n c e was c a r r ie d o u t a cco rd in g to a sy ste m a tic s t a t i s t i c a l d e sig n c a lle d a I c e n tr a l com p osite d e sig n in fo u r v a r ia b le s , and some d e - I t a i l s about t h i s p a r tic u la r ex p erim en ta l d e sig n are g iv e n In th e t e x t . T h is ex p erim en ta l d e s ig n was chosen so th a t th e e f f e c t s o f a l l th e v a r ia b le s and t h e ir m utual I n te r a c tio n s w ith each o th e r cou ld be a s s e s s e d w ith a minimum o f t e s t i n g e f f o r t . The e f f e c t s o f th e fo u r independent v a r ia b le s on ozone cra ck in g were a s s e s s e d by us© o f the fo llo w in g m easured re sp o n se s (dependent v a r ia b le s ) : th e !s e v e r it y o f ozone c r a c k in g , (SOC)max, th e d egree o f creep i under c o n sta n t lo a d , and th e **crack volum e.n i i C o n clu sio n s I The c o n c lu sio n s g iv en below are a g e n er a l summary j o f th e combined r e s u lt s from a l l th r ee o f the measured |r e s p o n s e s . ! 1 . Of th e fo u r v a r ia b le s s tu d ie d , th e one th a t 1 0 a p p e a r s t o h a v e t h e g r e a t e s t e f f e c t on o z o n e c r a c k i n g i s th e d e g r e e o f s t r a i n * H e x t i n l i n e i n im p o r ta n c e a r e th e | c r o s s - l i n k d e n s i t y a n d th e c o n c e n t r a t i o n o f HAF b l a c k . ■The am o u n t o f o i l a p p e a r s t o h a v e th e s m a l l e s t i n f l u e n c e Ion o z o n e c r a c k i n g . 1 2 . An i n c r e a s e i n th e d e g r e e o f s t r a i n w i l l c a u s e ia n i n c r e a s e i n o z o n e a t t a c k u n t i l th e s t r a i n r e a c h e s a c e r t a i n maximum ( a p p r o x i m a t e ly ) , a n d b e y o n d t h i s p o i n t a n i n c r e a s e i n s t r a i n w i l l h a v e b e n e f i c i a l e f f e c t s . T he i n f l u e n c e o f t h e d e g r e e o f s t r a i n b e ca m e s l i g h t l y s m a l l e r I j u p o n p r o lo n g e d e x p o s u r e . 3 . I n c r e a s i n g t h e c r o s s - l i n k d e n s i t y h a s t h e e f f e c t o f lo w e r i n g o z o n e c r a c k i n g . T h is e f f e c t i s e s s e n t i a l l y l i n e a r a n d s t a y s v e r y n e a r l y t h e sam e u p o n p r o lo n g e d e x p o s u r e . T he e f f e c t o f HAF b l a c k on o z o n e c r a c k i n g i s n o n - l i n e a r . An i n c r e a s e i n t h e c o n c e n t r a t i o n o f HAF h a s t h e e f f e c t o f d e c r e a s i n g o z o n e c r a c k i n g u n t i l t h e c o n c e n t r a t i o n r e a c h e s a c e r t a i n maximum ( a p p r o x i m a t e l y $0 p h r . ) . A f t e r t h i s maximum i s r e a c h e d , a n i n c r e a s e o f HAF h a s d e l e i t e r i o u s e f f e c t s . T he e f f e c t d e c r e a s e s s l i g h t l y u p o n p r o - ; lo n g e d e x p o s u r e . 5* A ny i n f l u e n c e t h a t th e a m o u n t o f o i l h a s on o z o n e c r a c k i n g i s v e r y s l i g h t . B e c a u s e t h e i n f l u e n c e i s so s m a l l , i t i s d i f f i c u l t t o d ra w a n y d e f i n i t e c o n c l u s i o n s a b o u t i t s e f f e c t * 6 . T he i n t e r a c t i o n te rm s i n t h e e q u a t i o n t h a t p r e - j d i c t t h e e f f e c t o f t h e f o u r v a r i a b l e s o n o z o n e c r a c k i n g a r e f o r t h e m o s t p a r t n e g l i g i b l e * i ■ 7* I n g e n e r a l , t h e a g re e m e n t b e tw e e n t h e e x p e r i m e n ta l r e s u l t s a n d t h e c a l c u l a t e d r e s u l t s i s f a i r , b u t | j c a u t i o n s h o u l d b e e x e r c i s e d w hen t h e e q u a t i o n s a r e u s e d t o I | p r e d i c t r e s u l t s i n t h e o u t e r r e g i o n s o f t h e e x p e r i m e n t a l f a c t o r s p a c e , i * e . , a t - 2 an d 2 l e v e l s (c o d e d u n i t s ) * i Com m ents o n S t a t i s t i c a l T e c h n iq u e T h is i s t h e f i r s t tim e t h a t a s t a t i s t i c a l p ro g ra m o f t h i s ty p e h a s b e e n a tt e m p t e d i n t h e s t u d y o f o z o n e [c r a c k i n g , a n d i n g e n e r a l t h e m e th o d p r o v e d t o b e r e l a t i v e - | l y g o o d . The t e c h n i q u e i s g o o d i n t h a t i t o f f e r s a m e th o d I f o r d e t e r m i n i n g t h e r e l a t i v e im p o r ta n c e o f v a r i a b l e s an d i . f o r d e te r m i n i n g t h e i n t e r a c t i o n b e tw e e n th e m . SE'F BHBMOBS 5 1 REFERENCES 1 . ASTM S t a n d a r d s o n R u b b e r P r o d u c t s , 1 9 th . E d i t i o n , M a rch I 9 6 0 . 2* B a l l , J . M ., R . A . Y oum ans, a n d A . F* R a n s e l l , "T he E f f e c t o f T e m p e ra tu r e o n t h e O zone C r a c k in g o f Two N a t u r a l R u b b e r Compounds,** R u b b e r Age 9 9 , p . ij.81, 191*4. 3 . B e b b in g to n , 0 , H . , R . ¥ • M u r ra y , an d P . R . S t o r y , ’* S t u d i e s o n t h e M ech an ism o f A n tio z o n a n t A c t i o n , ” B e l l T e le p h o n e l a b o r a t o r i e s , I n c . , M u rra y H i l l , New J e r s e y ( u n p u b l i s h e d ) . 4* B r a d e n , M ., a n d A . N . G a n t, "T h e A t t a e k o f O zo n e o n S t r e t c h e d R u b b e r V u l c a n i z a t e s , " J o u r n a l o f A p p lie d P o l y a e r S c i e n c e N o . 7 ,- I 9 6 0 ; P a r t I s T he R a te o f C u t G ro w th , p . 9 0 ; P a r t X Iz T he C o n d i t i o n s f o r C u t G ro w th , p . 1 0 0 . 5 . C o c h r a n , W. G ., a n d G. M. C o x , E x p e r i m e n t a l R e s i g n s , C h a p te r 8A, J . W ile y a n d S o n s , 1957* 6 . D e c k e r , G. E . , a n d R . W. W is e , "T h e S t r e s s R e l a x a t i o n M eth o d f o r M e a s u rin g O zone C r a c k i n g ," R u b b e r W o rld 1 4 6 , p . 6 6 , A p r i l 1 9 6 2 . 7 . H e r l i e s k a , E . , a n d E . G. P a r t r i d g e , " C o n t i n u a t i o n o f t h e S tu d y o f O zone R e s i s t a n c e o f N e o p re n e V u l e a n i - z a t e s , " USCEC R e p o r t 8 0 - 1 0 2 , D ecem b er 1 9 6 1 . 8 . K a t s e n i s , P . , and E . G. P a r t r i d g e , " S tu d y o f O zone R e s i s t a n c e o n N e o p re n e V u l c a n i z a t e s , " USCEC R e p o r t 8 0 - 1 0 1 , A u g u s t I 9 6 0 . 9 . K im , Y . C . , " S tu d y o f V a r io u s F a e t o r s I n v o l v e d i n t h e R e s i s t a n c e o f E l a s t o m e r ! c V u l c a n i z a t e s t o A tm o s p h e ric C o n d i t i o n s , " USCEC R e p o r t 9 4 - 1 0 3 , J u l y 1964* 1 0 . O ng, J . , a n d E . G. P a r t r i d g e , " C o n tin u o u s S tu d y o f V a r io u s F a c t o r s I n v o l v e d i n t h e R e s i s t a n c e o f E l a s t o - m e r ic V u l c a n i z a t e s t o A tm o s p h e ric C o n d i t i o n s , " USCEC R e p o r t 9 4 - 1 0 2 , J u l y 1963* 9 2 53 1 1 . P a t e l , N ., a n d E . G . P a r t r i d g e , C o n t i n u a t i o n o f t h e S tu d y o f O zone R e s i s t a n c e o f N e o p re n e V u l c a n i z a t e s , ” BSCBC R e p o r t 8 0 - 1 0 3 , A u g u s t 1 9 6 2 . 1 2 . P o e r , B . G ., a n d E . G. P a r t r i d g e , “ S tu d y o f V a r io u s F a c t o r s I n v o l v e d i n t h e R e s i s t a n c e o f E l a s t o m e r i c V u l c a n i z a t e s t o A tm o s p h e ric C o n d i t i o n s , ” USCK3 R e p o r t 91^-101, O c to h e r 1 9 6 2 . 13* S c h a e f , C . , ”A Q u a n t i t a t i v e O zone T e s t , ” R u b b e r W o rld l i i 5 , p . 7 9 , F e b r u a r y 1 9 6 2 . Ilf.* V e i t h , A. G ., "A R o u tin e Q u a n t i t a t i v e M eth o d o f Mea s u r i n g O zone C r a c k in g a n d I t s U se i n O u td o o r D ynam ic T e s t i n g , ” B . F . G o o d r ic h R e s e a r c h C e n t e r , B r e c k s - v i l l e , O h io ( u n p u b l i s h e d ) • 15>. V e i t h , A . G ., “ Q u a n t i t a t i v e M e a su re m e n t o f R a te o f O zone C r a c k i n g , ” ASTM STP N o. 2 2 9 , p . 9 7 , 1 9 5 8 . 1 6 . V e i t h , A . G ., “ S e r i e s o f L e c t u r e s o n E x p e r im e n ta l S t a t i s t i c a l T e c h n iq u e s ," B . F* G o o d r ic h R e s e a r c h C e n t e r , B r e c k s v i l l e , O h io ( u n p u b l i s h e d ) . 17* V e i t h , A . G *, "T h e V is e u r o m e te r - A S tu d y o f V a r i a b l e s A s s o c i a t e d w i t h I t s U s e ," B . F . G o o d ric h R e s e a r c h C e n t e r , B r e c k s v i l l e , O h io ( u n p u b l i s h e d ) . 1 8 . W a d e lin , C . W ., " D e te r m in a t io n o f 0 z o n e a n d O th e r O x id a n ts i n A i r , " A n a l y t i c a l C h e m is tr y 2 9 , N o. 3 , p . IjljJL, M a rch 1957* ( r j i i i j i ! j A P P E N D I C E S j I 5k APPENDIX I SOURCES OF MATERIALS USED j ' SBR, S -1 5 0 0 S u l f u r S t e a r i e A c id Z in c O x id e i ; HAP B la c k (V u lc a n 3H) I CBS, S a n to c u r e ( N - C y c lo h e x y l- j 2 - b e n z o t h i a z o l e s u l f e n a m i d e ) ! C i r c o s o l NS ( N a p h th e n ic T ype I O i l ) , P o ta s s iu m I o d i d e , P o ta s s iu m l o d a t e , P o ta s s iu m P h o s p h a t e , 1 S o d iu m P h o s p h a t e , S o d iu m I C a r b o n a t e , S o d iu m T h i o s u l p h a t e , j S u l f u r i c A c id S u p p l i e d b y S h e l l C h e m ic a l C o . L os A n g e le s C h e m ic a l C o. The New J e r s e y Z in c C o . C a b o t C o rp . M o n san to Go* S u n O i l C o . A l l i e d C h e m ic a l C o r p . APPENDIX I I EXPERIMENTAL DATA TABLE IS (S °G )m ax MEASUREMENTS ( R e p o r te d I n r e t i c l e u n i t s on a I 5 x b a s i s ) 1 D ay 2 D a y s 3 D ay s Run N o . I 2 I 2 1 2 1 1 7 .6 19*8 3 0 .6 3 2 .2 4 6 .3 5 3 .5 2 9*3 9 . 6 2 2 .1 2 1 .0 3 1 .0 35*8 3 9 .2 9 *3 l£ * 9 1 6 .9 2 6 .6 2 5 * 6 4 4*4 4 *7 1 1 .6 1 2 .8 2 1 .0 2 5 * 4 5 13*5 1 1 .5 2 4 .9 2 3 - 4 5 6 .1 4 5 * 5 6 1 4*5 1 2 .0 2 8 .6 2 4 .6 4 3 * 5 4 0 .9 7 2 5 .4 1 3 .9 4 0 .5 21*6 5 1 .9 2 7 .1 8 4*1 9 . 5 1 3 .0 2 2 .3 2 2 .7 3 3 .0 9 8 .5 1 0 .5 2 5 .9 3 5 .1 5 5 * 4 5 6 .0 10 4*3 5 . 0 1 6 .0 1 2 .9 3 2 .2 2 1 .7 11 1 0 .5 6 .8 2 5 .4 1 4 .8 4 3 * 5 3 0 .2 12 5 .6 4*4 l 4 . 0 1 0 .1 2 3 .3 2 5 .2 13 1 6 .8 1 2 .6 4 0 .5 3 5 .6 7 1 .0 5 9 .9 Ik 6 .2 7 .0 1 5 .0 16*6 4 3 * 8 3 6 .3 15 6 .0 6 .9 2 7 .8 2 9 .6 4 1 .1 4 2 .3 16 2 .9 2 .7 8 .2 7 .6 1 8 .7 1 6 .9 1 7 7 .0 6 .9 1 9 .3 1 9 .6 3 1 .2 3 5 * 4 18 4*7 £ .3 1 0 .8 1 0 .5 24*3 2 5 .8 19 7 .9 8 .1 2 1 .2 2 2 .8 4 3 .5 4 9 .5 20 7*7 8 . 4 1 7 .8 2 1 .6 3 2 .8 3 6 .6 21 4 4 6 .0 1 3 .3 1 2 .5 2 8 .8 2 6 .9 22 5 * 4 7 -7 1 5 .0 18 *8 2 6 .9 £ o . 0 23 1 1 .3 1 2 .6 1 6 .8 1 8 .5 2 1 .4 2 4 *2 2k 2 .7 2 .5 1 0 .5 IO . 4 2 0 .7 1 9 * 3 25 3*5 3 .6 1 5 .1 1 6 .7 3 0 .4 3 1 .6 26 6 .7 4 . 6 1 7 .9 1 3 -3 3 6 .4 2 5 * 4 2 ? 4*9 4*5 1 5 .9 1 3 .9 3 0 .3 3 5 .5 28 5 * 4 5 * 8 1 6 .5 1 6 .7 3 4 .9 3 1 * 5 29 6 .3 5 .9 1 7 .8 1 5 .0 3 6 .2 2 9 .8 30 5 . 8 5 .2 1 6 .8 l £ . 8 3 3 .8 3 2 .5 31 5 .8 4*9 1 5 .8 l £ . l 3 2 .7 31*9 56 57 i t TABLE 16 ( c o n * t . ) If.' B a y s 5 B ays R un N o. 1 2 1 2 1 7 2 .5 6 7 .0 7 0 .2 7 8 .3 2 4 8 .1 5 0 .4 — 5 8 .5 3 3 7 * 0 4 2 .6 4 6 .7 5 1 .0 4 3 5 .2 3 3 .6 4 5 .7 5 5 2 .4 5 8 .7 7 0 .3 7 7 .0 6 5 7 .5 6 0 .5 6 3 .5 6 k .5 7 5 3 .8 3 7 .8 6 2 .5 3 8 .0 8 4 3 .4 5 1 .0 5 2 .3 6 2 .2 9 7 4 .1 7 9 .0 8 2 .7 8 5 * 5 10 5 6 .3 3 6 .7 7 4 .0 5 1 .0 11 7 1 .8 3 9 .8 1 0 0 .5 7 1 .1 12 4 7 .0 3 3 .0 5 6 .1 4 7 .0 13 8 6 .5 7 3 .8 9 7 .5 8 0 .0 3 4 6 1 .5 5 5 .7 7 2 .6 7 7 .6 1 5 5 2 .1 5 4 .0 8 4 .5 6 3 .O 16 2 8 .2 2 5 .8 4 0 .5 4 2 . 4 17 5 3 .3 5 6 .5 8 3 .2 7 8 .0 18 3 9 .1 1*4.7 4 7 .3 6 2 .7 19 7 3 .2 7 1 .5 1 0 0 .6 8 0 .2 20 5 2 .2 5 1 .6 6 3 .9 6 0 .1 21 3 9 .7 4 5 . 6 4 9 .9 5 7 .0 22 6 6 .8 7 0 .6 7 9 .4 7 1 .4 23 3 2 .2 3 1 .6 4 2 .5 3 5 .4 2k 4 0 .5 4 0 .8 6 1 .1 6 1 .4 25 5 1 .8 5 2 .6 6 6 .6 5 9 .5 26 5 3 .1 4 8 .8 6 7 .0 6 k .3 27 5 0 .7 5 6 .1 6 3 .8 6 6 .5 2 8 5 4 .8 5 2 .5 65*6 6 6 .8 29 5 6 .8 4 4 .5 6 9 .1 5 3 .0 3 0 5 5 .0 4 9 .5 6 5 .2 6 2 .8 3 1 5 3 .0 5 4 .0 7 2 .8 5 8 .5 TABLE 1 ? CREEP MEASUREMENTS ( R e p o r te d i n p e r c e n t i n c r e a s e i n l e n g t h ) 6 H o u rs 12 H o u rs 18 H o u rs R un N o . 1 2 1 2 1 2 1 2 .3 # 1 .7 6 *k* 5 . 0 1 2 . 2* 9 . 2 2 k . l 3 * k 7 .2 6 .8 1 0 .9 9 . 2 k . l 3 .0 7 .5 5 *9 1 0 .6 1 0 .2 k 2 .5 * 2 .3 6 .3 * 5 . 1 9 .6 * 7 .1 5 3*7 3 .1 7 .5 7 .5 1 2 .8 1 2 .5 6 k .ii* 3 .0 7 . 3* 5 . 1 1 0 . 3* 8 .5 7 if-.l 3 .8 7 .5 8 .7 1 1 .6 l k . o 8 2 .7 2 .8 5 * 4 k .9 7 .8 7 .0 9 6 .9 * 7 .1 1 3 .9 * 13 .2 2 0 .0 * 1 8 .2 10 k *7 k .o 10 . 4 9*3 ik * 6 11 .k 11 k .3 5 .2 1 2 .6 10 .2 1 9 .7 i k . 2 12 I} . .5 k .6 1 0 .3 7 .1 1 3 .5 1 0 .5 7 .0 6 .5 1 3 .5 1 2 .7 1 9 .0 1 8 .2 i k 6 .0 * 3 .9 1 1 .9 * 8 .3 1 6 . 1* 1 1 .5 15 6 .6 6 .1 1 0 .2 1 1 .2 1 3 .3 1 5 4 16 3 .0 * k .2 6 .6 * 6 .8 1 0 . 5* 9 - 9 17 6 .2 * 6 .o 13 4 * 1 1 .9 1 6 . 8* 1 7 .8 18 k . 7* 5 .2 7 . 7* 8 .2 1 2 . 3* 1 1 .8 19 6 .6 * 5 .3 i k » i * 9 . 8 17 4 * ik * 7 20 5 .2 * 5 .1 9 . 3* 7 .6 1 2 . 5 * 1 1 .2 21 7 .9 6 *2 1 1 .5 1 1 .1 15^9 1 5 .3 22 5 .6 5 .9 7 .9 9 .2 1 1 .8 1 3 .1 23 1 .3 i . k k* 2 3 . k 6 .7 5 * 7 4 2 .8 ? • ? 7 .3 7 .9 1 0 .5 1 0 .0 25 k *7 4 .6 7*9 7 .9 1 0 .8 1 1 .1 2 6 5 .7 5 .0 9 . 3 8 .9 1 3 .2 1 1 .8 2 Z 5 .1 * k .3 9 . 5 * 8 .5 1 5 4 * 1 2 .3 28 k . 2 3 .3 8 .2 6 .9 1 1 .2 9 4 29 k . 9 * k .9 9 .8 * 8 .9 ik * 5 * 1 2 . k 30 k *3 3 .3 8 .5 7 .2 1 2 .0 9 . 6 3 1 3 .5 k*2 8 .6 6 .6 1 2 .2 1 0 .3 * T h e s e v a l u e s a r e i n a l m o s t e v e r y e a s e h i g h e r t h a n th e s e c o n d sa m p le v a l u e s b e c a u s e th e y w e re p l a c e d n e a r e r t o t h e i n l e t o f t h e o z o n e c h a m b e r. T h ey w e re e x c lu d e d fro m t h e c a l c u l a t e d r e s u l t s b e c a u s e i t w as t h o u g h t t h e y m ig h t c a u s e s p u r i o u s r e s u l t s . TABLE 17 (con* t.) 59 2k H o u rs 3 0 H o u rs 3 6 H o u rs H un H o . 1 2 1 2 1 2 1 17*9* l k . k 2 6 . 2* 1 9 .6 3 k 4 * 2 6 .2 2 l k . 7 4 . 0 1 8 .8 1 8 .7 2 2 .2 2 1 .8 ? l o .8 4 . 3 2 0 .5 2 0 .6 2k . 7 2 6 .8 k 13 4 * 1 0 .9 18 4 # 1 5 .0 2 3 . 6* 19 4 5 1 8 .8 1 7 .8 2 6 .3 2 6 .2 3k* 8 3 7 .0 6 l k . k » 1 2 .3 1 9 . 2* 1 5 .0 2 k - 6* 19 4 7 1 5 .8 2 1 .3 1 9 .7 2 9 .3 2 6 .0 3 7 .7 8 1 0 .7 9 .9 i k • 7 4 . 8 1 7 .7 1 7 .9 9 2 6 . 6* 2 3 .2 3 5 .8 * 2 9 .9 k 5 .5 * 3 6 . 4 16 1 8 .5 1 8 .9 2 k . 0 23 4 2 8 .0 2 7 .9 11 2 7 .0 1 8 .3 3 8 .6 2k*2 5 3 .7 3 2 .6 12 13 1 9 .3 2 k . 8 4 . 8 2 3 .8 2 5 .1 3 2 .6 1 8 .2 3 1 .8 2 2 4 k o .6 l k 2 3 . 1* 1 5 .6 2 7 . 6* 2 0 .2 3 2 . 9* 2 3 .9 15 , 1 6 .6 1 9 .5 2 1 .1 2 5 .8 2 5 .7 3 5 .0 16 1 5 . 6# 1 2 .7 2 1 .2 * 1 5 .9 2 7 . k * 1 9 4 17 27 4** 2k . 0 k o . 9* 3 3 .2 5 5 . 0* k 3 .6 18 1 7 .5 * 1 7 .0 23 4 * 2 1 .6 2 7 . 7* 2 5 .6 19 2 k - 6* 2 2 .8 3 3 4 * 32 .k k 6 .o * k 3 .0 2 0 19 .5 * 1 6 .8 3 0 . 6* 2 3 .6 B ro k e n 3 3 .5 21 20 . k 2 0 .9 2 7 4 2 8 .8 3 2 .8 3 2 4 22 1 7 4 1 8 .0 2 3 .3 2 5 .6 3 0 .7 3 2 4 23 1 0 .6 8 .1 1 6 .0 1 2 .8 2 2 .8 1 7 4 2 k 1 3 .9 1 3 .6 1 8 .6 1 8 .2 2 3 .0 2 2 .9 25 4 . 8 4 . 8 1 9 .3 2 1 .3 2 k . 9 2 7 .9 26 1 7 .1 1 5 .8 2 2 .0 2 1 .0 2 8 .0 2 5 .8 27 2 1 . 8* 1 6 .6 2 8 . 9* 2 1 .0 3 6 .2 * 2 6 ,0 28 16 4 12 .5 2 1 .8 1 6 .8 2 7 .0 2 k 4 29 1 9 . 6* 1 6 .2 2 6 . 7* 2 1 .3 3 k ‘ 2* 2 6 .5 30 1 6 .8 l k . 5 2 3 .3 1 9 .5 2 9 .2 2 3 .k 3 1 1 7 .2 l k - 5 2 2 .7 1 8 .9 2 8 .7 2 2 .8 * S e e n o t e , p . £ 8 . I I TABLE 1? {con* t.) 60 Run H o . 1*2 H o u rs 1 2 I48 H o u rs 1 2 1 1*5.1* 3 4 .9 5 7 . 6# 1*1*.5 2 2 7 .6 2 6 .7 2 9 .3 2 8 .2 3 3 1 .2 3 3 .5 39*2 1*1.3 k 2 8 . 1 ** 22 .9 3 0 . 2* 2 5 .5 5 1 *7 .8 5 2 * 4 6 k -9 6 9 .5 6 2 9 .5 * 2 3 .1 3 2 .5 * 2l* .8 7 3 2 .7 149.8 4 2 .1 6 9 .8 8 2 1 .6 2 2 .2 2 2 .8 2 3 .6 9 5 6 *6# 1*3-9 6 7 . 8# • 5 0 .5 10 3 3 .3 3 2 .0 3 7 .0 3 7 .2 11 B ro k e n 1 *4 .0 B ro k e n B ro k e n 12 3 6 .1 2 6 .7 1*1.5 3 0 .7 13 14-9*3 5 1 .2 5 7 .6 6 1 .5 4 3 9 .0 * 2 8 .5 4 4 *5# 3 2 .9 15 3 2 .3 148.7 I4 O.7 B ro k e n 16 3 2 . 2# 2 3 . 1 4 3 7 . 6* 2 7 .2 17 6 8 .5 # 6 4 .5 9 2 . 4# 7 1 .2 18 31 *o# 2 9 .8 3 7 .5 * 3 5 .6 19 5 5 .5 # 5 5 .p 6 4 .2 # 6 7 .3 20 B ro k e n 4 3 . 4 B ro k e n B ro k e n 2 1 3 8 .2 3 8 .3 W -.5 1*7.7 22 3 6 .1 I4 O.O 1*3.8 1 * 8 .8 23 2 8 .5 2 0 .0 3 3 .2 2 5 .2 25. 2 6 .6 2 7 .2 3 0 .1 3 0 .9 25 2 7 .5 3 3 .1 3 1 .8 38.1* 26 3 3 .6 3 0 .8 3 9 .8 3 5 .8 27 1*5.7# 3 2 .0 5 5 .2 # 3 7 .0 28 34*1 2 8 . k 3 5 4 2 9 .7 29 1 4 . 3 *1*' 3 2 .6 5 2 .5 # 3 8 .2 3 0 3 4 .8 2 9 .1 k l.l* 3 3 .2 31 35.1* 2 8 .0 1*1.1 3 3 .2 * S e e n o t e , p . 5 8 . TABLE 18 'GRAGK volum e m ea su r em en ts ( R e p o r te d I n i n . ^ / l n . ^ x 10^-) 6 H o u rs 12 H o u rs 1 8 H o u rs 'Run No* 1 ~ 2 1 2 1 2 1 14*1 1 6 .1 2 2 .2 2 2 .2 2 8 .3 3 0 .3 2 14 * 1 1 4 .1 2 2 .2 2 2 .2 2 6 .3 2 6 .2 3 3 4 .1 3 4 .1 2 0 .1 2 2 .2 2 8 .3 3 0 .3 4 14*1 3 4 .1 2 4 .2 2 4 .2 2 6 .2 2 6 .2 5 3 4 .1 i 4 * i 2 0 .1 2 2 .2 • 2 6 .3 2 6 .3 6 1 2 .1 1 0 .0 1 6 .1 1 8 .1 2 0 .2 2 4 .2 1 1 0 .0 1 0 .0 2 4 .2 2 4 .2 2 8 .3 2 8 .3 8 8 .0 1 0 .0 1 4 .1 I 4 . I 2 0 .1 2 0 .1 9 2 6 .3 2 8 .3 4 0 .6 4 8 .9 4 0 .6 5 5 .2 5 9 .3 10 2 2 .2 1 8 .1 3 8 .6 5 7 .2 5 1 .0 11 3 2 .4 3 8 .6 5 3 .0 5 9 .3 55*1 71*9 7 4 .© 12 3 2 .il. 3 4 .4 5 9 .3 6 9 .7 6 7 .7 13 3 2 .i. 3 0 .4 4 8 .9 4 2 .7 6 1 .5 5 7 -3 3 4 2 0 .2 2 6 .3 3 8 .6 4 2 .7 4 8 .9 5 1 .0 1 5 3 0 .3 3 0 .3 4 4 - 8 4 2 .7 5 7 .3 5 5 .1 16 2 8 .3 2 6 .3 4 k . 8 4 2 .7 5 5 .1 5 1 .0 17 2 k . 2 2 0 .0 3 6 .5 3 2 .4 44*7 4 0 .6 18 19 1 6 .1 2 0 .2 1 8 .1 2 6 .3 3 0 .3 30 4 2 8 .3 3 6 .5 3 2 . k 4 0 .0 20 2 6 .3 2 8 .3 4 0 .0 4 6 .8 50*9 5 7 .2 21 2 4 .2 2 2 .2 3 8 .5 3 6 .5 4 4 .7 4 0 .6 22 2 2 .2 1 8 .1 3 2 .4 2 6 .3 4 0 .6 3 2 .4 23 I k . ! 1 2 .1 2 2 .2 2 2 .2 2 6 .3 2 8 .3 2 6 .3 2 6 .3 4 2 .7 4 0 .6 5 3 .1 5 1 .0 25 2 2 .2 2 4 .2 3 0 .3 4 0 .6 3 8 .6 5 1 .0 26 2 2 .2 22 .2 3 2 .4 3 0 .3 4 0 .6 4 0 .6 2l 1 6 .1 1 6 .1 3 0 .3 3 0 .3 3 4 * 4 3 4 * 4 28 1 8 .1 1 8 .1 2 8 .3 3 0 .3 3 2 . k 3 4 .4 29 2 k . 2 2 0 .1 3 4 * 4 2 8 .3 4 0 .6 3 8 .5 30 1 8 .1 2 0 .2 3 0 .3 3 2 .4 3 8 .6 3 8 .6 3 1 2 0 .2 1 8 .1 3 0 .3 3 4 * 4 4 0 .6 4 2 .7 62 TABLE 18 (con1t.) 2 4 H o u rs 30 H o u rs 36 H o u rs B un H o . 1 2 1 2 1 2 1 3 4 4 3 4 4 k 2 . J 4 2 .6 4 6 .8 4 6 .8 2 3 4 4 3 6 .5 i}.0 *6 4 2 .7 k k .7 4 4 .7 3 3 8 .5 3 8 .5 4 2 .6 4 4 .7 4 6 .8 5 0 .9 4 3 0 .3 3 2 .k 3 4 4 3 8 .5 k o .6 4 4 .7 5 3 4 - 4 3 2 4 3 6 .5 4 o .6 4 2 .7 4 2 .7 6 2 8 .3 3 0 .3 3 8 .5 3 8 .5 4 0 .6 4 2 .7 7 3 2 4 3 0 .3 3 4 4 3 6 .5 4 0 .6 4 0 .6 8 2 6 .3 2 8 .3 2 8 . 4 3 2 .4 3 0 .3 3 6 .5 9 65 «6 6 9 .8 7 8 .3 8 2 .5 8 6 .8 9 1 .0 10 6 3 .5 5 9 .3 7 1 .9 6 5 .6 7 4 .0 6 7 .7 11 8 0 .3 8 k . 6 8 6 .7 9 3 .1 9 5 .2 9 9 .5 12 7 8 .2 7 8 .2 8 2 .4 8 6 .7 8 8 .8 9 3 .1 6 9 .9 6 5 .7 7 6 .2 7 6 .2 8 4 -7 8 6 .6 I k 5 7 .2 5 9 .3 6 5 .6 6 7 .7 7 6 .2 15 6 5 .7 6 5 * 0 7 1 .9 7 1 .9 7 8 .2 7 6 .1 1 6 6 3 .5 5 9 .3 6 7 .7 6 7 .7 7 1 .9 7 4 .0 17 5 3 .0 5 3 .0 5 9 * 2 5 9 .3 6 7 .7 6 5 .6 18 k o .6 M>.6 4 8 .9 5 1 .0 5 3 .0 5 5 .1 19 1 4 B-9 5 5 .2 5 7 .2 6 1 .4 6 3 .5 6 5 * 6 2 0 5 9 .3 6 7 .6 6 5 .5 7 3 .9 7 1 .8 8 6 .6 21 5 5 .1 5 5 .1 6 5 .5 6 1 .3 6 9 .7 6 7 .6 22 5 5 .1 1 4 * 7 6 3 .5 5 3 .0 6 5 .5 5 7 .2 23 3 2 4 3 2 . 1 4 . 3 4 4 3 4 « 4 3 8 .5 3 4 .4 2 4 6 3 .5 5 9 .3 7 1 .9 6 7 .7 8 2 .5 7 4 .0 25 4 6 .8 5 9 * 3 4 8 .9 6 i 4 5 5 .1 6 5 .6 26 4 6 .8 4 6 .8 6 1 .4 5 9 .3 63 4 6 3 .4 2 7 4 2 .7 k o .6 5 0 .9 4 6 .8 5 5 .1 5 5 .1 28 |4 * 7 k 2 .7 5 5 .1 3 0 .9 5 7 .2 5 3 .0 29 £ 8 1 9 1 4 .7 5 7 .2 5 0 .9 6 l . k 5 9 .3 30 4 6 .8 4 0 .8 5 3 .0 5 3 .o 6 l . 4 5 5 .1 31 4 6 .8 5 3 * 0 5 7 .2 5 9 .3 6 3 4 6 5 .6 63 TABUS 18 (con’t.) 4 2 H o u rs i|.8 H o u rs B un Ho* 1 2 1 2 1 4 8 .9 5 3 .0 5 7 .2 2 5 0 .9 5-6.8 . 5 3 .0 3 5 3 .0 5 5 .0 6 l* 3 4 4 O.6 4 6 .8 5-6.8 5 IM 4..7 46.8 5 3 .0 6 5.0.6 5 .6.8 5 -6.8 5 -8*9 7 5 2 .6 4k . 7 5 8 .8 5 8 .8 8 35*5 3 6 .5 5 o .6 5 o .6 9 9 5 .3 9 5 .3 9 9 .6 1 0 1 .7 10 85*7 7 8 .3 9 1 .0 8 4 .6 11 9 9 * 5 1 1 0 .3 1 0 3 .8 1 1 6 .8 12 9 5 * 2 9 9 .5 9 9 * 5 1 0 5 .9 4 8 .9 5 3 .0 5 0 .9 4 6 .8 5 3 .0 5 5 .0 4 0 .6 4 6 .8 55*7 4 6 .8 4 0 .6 4 6 .8 4 2 .6 4 5 .7 3 4 .5 3 6 .5 9 5 .3 9 5 .3 8 4 .7 7 8 .3 99 *5 1 1 0 .3 9 5 .2 9 9 * 5 9 1 .1 9 1 .1 7 6 .2 8 0 .4 8 4*6 8 2 .5 8 0 .4 8 2 .5 7 3 -9 6 9 .7 5 9 .3 5 9 .3 6 9 .8 7 4 .1 7 8 .1 9 3 .0 8 0 .3 7 8 .1 7 1 .9 61 *5 5o .6 3 6 .5 9 1 .0 8 2 .5 0 I . 4 7 6 .1 - 6 9 .8 6 7 .7 6 3 .5 5 9 .3 6 3 .4 5 9 .3 6 7 .6 6 7 .6 6 7 .7 61 *4 6 7 .0 69 *8 15 8 4 .6 8 2 .5 8 S .9 8 6 .7 8 4 .6 88*9 7 6 .0 7 6 .1 6 5 .6 6 5 * 6 7 4 .1 7 8 .3 8 5 .5 1 0 5 .9 8 2 .3 8 2 .3 7 8 .2 6 5 .6 4 2 .6 k o .6 0 7 .5 8 8 .9 6 5 .6 7 8 .3 8 0 .3 7 6 .1 6 9 .7 6 5 .5 6 9 .7 6 5 .5 7 1 .9 6 9 .7 7 4 .0 6 7 .7 73*9 8 0 .3 APPENDIX I I I SIGNIFICANCE OF COEFFICIENTS TABLE 19 SIGNIFICANCE OF COEFFICIENTS FOE (SOC) PREDICTION m ax T-TEST VALUES C o e f f i c i e n t 1 D ay 3 D ays 5 D ays b i - 3 . 0 - k - k - 6 . 2 b 2 - 1 . 5 -1^.5 - 6 . 5 b 3 0 .9 2 .2 2 .0 \ - 3 i 2 0 .5 I4-.8 b l l 0 .9 0 .1 0 .8 b 22 1 .8 2 . 5 2 .7 b 33 1 .0 1 . 2 hkh 1 .5 -1.1}. - 3 . 3 b 1 2 - 0 . 2 0 .9 - 0 . 1 b 13 - 0 . 1 - 0 . 1 1 .1 b 3 4 0.1}. - 2 . 1 - 3 . 5 b 23 0 . 2 -0.1}. - 1 4 . b 2lj. 0 . 1 - 0 . 5 0 . 5 b 3 ^ - 0 . 5 - 0 . 1 - 1 . 0 6k 65 TABLE 20 SIGNIFICANCE OF COEFFICIENTS FOR CREEP PREDICTION T-TEST VALUES C o e f f i c i e n t 6 H o u rs 18 H o u rs 36 H o u rs b l — 2 * 2 - 7 . 1 - 7 . 8 b £ - 0 . 4 - 2 . 7 - 2 .2 b 3 - 0 .1 - 1 .1 - 0 .6 \ 4 * 5 7 .0 3 .3 H H & 1 .0 3 . 0 2 .3 b 22 0 . 5 1 . 1 3 .7 b 33 2 .2 2 .2 1 .3 b4 4 - 3 . 7 -3 * 6 - 2 . 8 b 1 2 - 0 .2 - 0 . 4 - 0 .1 b 13 - 1 .2 - 1 . 5 - 1*6 b ll|. - 1 . 8 - 1 .8 - 0 .8 b 23 0 . 4 - 0*6 - 1 .6 b 24 - 0 .8 - 1 . 1 — b 3 4 - 0 . 3 - 2 .1 - 2 . 2 66 TABLE 21 SIGNIFICANCE OF COEFFICIENTS FOR CRACK VOLUME PREDICTION T-TEST VALUES i I C o e f f i c i e n t 6 H o u rs 1 2 H o u rs 2 4 H o u rs 36 H o u rs 4 8 H o u rs b i -2 * 2 - 0 . 7 - 1 . 8 - 2 . 5 - 2 . 4 b 2 1 * 5 2 .1 1 .5 1 .2 1 . 4 b 3 “ 1 «4 - 2 .1 - 1 . 9 - 2 . 4 - 2 .8 b* 9 .5 9 .7 1 0 .0 1 2 .1 1 3 .5 H H & - 0 . 4 N O W - 0 .1 - 0 .6 1 C M 1 O J & 1 .9 1 .7 2 . 0 2 .3 2 .3 b 33 G .4 0 . 4 1 .0 0 .9 0 .7 b I * 1 1 I 1 - 0 .If. » « ■ - 0 .1 - 0 .6 - 1 . 2 b 1 2 1 .0 0 .2 - 0 . 1 0 . 4 0 . 2 b 13 - 0 . 4 - 1 . 4 - 0 .2 0 .2 0 .6 * 1 4 - 1 ,2 0 .8 - 0 . 3 i H . O b 23 - 1 .8 - 1 . 4 - 1 . 3 - 1 . 7 - 1 .6 h2k 2* 4 1 .5 1 .3 1 .2 1 . 0 * 3 4 0 .7 - 0 .6 - 0 .6 - 0 .6 - 0 .6 APPENDIX IV RECIPES AND PHYSICAL PROPERTIES OP COMPOUNDS COMPOUND S - l (RUNS 2 3 -3 1 ) I n g r e d i e n t s _ P h r SB R -1500 1 0 0 .0 Z in c O x id e 5 .0 0 S t e a r i c A c id 1 .5 0 HAP B la c k 5 0 .0 C i r e o s o l NS 1 0 .0 CBS 0 .9 7 S u l f u r I .8 3 T o t a l 1 6 9 * 3 0 PHYSICAL PROPERTIES C u re Tim e 1 0 0 $ a t 3 0 7 °P M o d u lu s M in u te s P S I 3 0 0 $ M o d u lu s P S I T e n s i l e S t r e n g t h P S I E l o n g a t i o n a t B re a k % • 1$ 1 6 0 & o 1 7 1 0 7 9 0 20 210 1 0 6 0 2 6 8 0 6 7 0 3 0 2 60 l £ i o 3 160 5 5 0 kS 3 2 0 1 8 1 0 3I3 .8O 5 3 0 60 3 2 0 1 8 9 0 351|-0 5 1 0 OPTIMUM CURE TIME - i j . 0 minutes 67 6 8 COMPOUND S-2 (RUNS 1 & 9) I n g r e d i e n t s SE R -1500 Z in c O x id e S t e a r i c A c id HAP B la c k O i r c o s o l NS CBS S u l f u r T o t a l PHYSICAL PROPERTIES C u re T im e a t 3 0 7 ° F 100$ M o d u lu s M o d u lu s T e n s i l e S t r e n g t h M in u te s P S I P S I P S I 20 1 2 0 3 10 m m 3 0 150 6 00 2 8 7 0 4 5 160 800 3 7 2 0 6 0 1 8 0 850 3450 80 1 8 0 90 0 3500 pfar 100.0 5 .0 0 I .5 0 3 5 .0 5 . 0 0 .8 3 - i g g L 1 4 8 .8 6 a t B re a k % . - 800 OPTIMUM CURE TIME - 45 minutes 69 com pound s - 3 C huns 2 & 1 0 ) In g r e d ie n ts SBR-l£00 Z inc Oxide S te a r ic A cid HAP B lack C ir c o s o l NS GBS S u lfu r T o ta l 100.0 5* 1 .5 0 3 5 .0 5 .0 1 . 2 .1 8 11*9 . 8 2 Cure Time ;a t 3 0 ? °F I M inutes I 15 30 k$ 60 PHYSICAL PROPERTIES Modulus P S I 160 Modulus PSI 710 11*90 1610 1630 T e n s ile S tren g th PSI 3790 3 6 7 5 E lo n g a tio n At Break 830 5 5 0 £20 OPTIMUM CURE TIME - 30 minutes COMPOUND S - i j . (RUNS 3 & 11) ; I n g r e d i e n t s SBR-l^OO ! Z in c O x id e j S t e a r i c A c id i HAP B la c k I ; C i r c o s o l NS CBS S u l f u r T o t a l JSSSL 1 0 0 .0 5.00 1*50 65.0 5 .0 0 .8 3 178.86 C u re Tim e ,a t 3 0 ? °P M in u te s kS 60 80 PHYSICAL PROPERTIES M od u lu s P S I 5 1 0 590 5 7 0 M odulus P S I 2700 T e n s i l e S t r e n g t h 2160 3ij.G0 E l o n g a t i o n a t B re a k W > 360 OPTIMUM CURE TIME - 50 minutes I 7 1 compound s -5 Chuns 1 + & 12) I n g r e d i e n t s SB R -1500 Z in c O x id e S t e a r i c A c id HAP B la c k C i r c o s o l NS CBS S u l f u r T o t a l J2S£L 100.0 5 . 0 1 .5 0 6 ^ .0 5 . 0 1. 1 1 + 2 .1 8 1 7 9 .8 2 C u re Tim e a t 3 0 7 °P ■ M in u te s ! * \ 20 k$ 60 PHYSICAL PROPERTIES M o d u lu s P S I 5 5 0 700 850 880 3 0 0 $ M o d u lu s P S I 1600 2 600 T e n s i l e S t r e n g t h P S I 3*1-25 381+0 E lo n g a t i o n a t B re a k 1 + 1 0 280 OPTIMUM CURE TIME - 25 minutes 72 C O M P O U N D S- 6 (O TW S 5 & 13) I n g r e d i e n t s p h r SBR 1 0 G .0 ! Z in c O x id e 5 * 0 S t e a r i c A c id 1 .5 0 H AF B la c k 3 5 .0 G i r c o s o l HS 15*0 OBS 0 .8 3 S u l f u r 1 .5 3 T o t a l 1 5 8 .8 6 PHYSICAL PROPERTIES Cure Time 100$ 300$ * T e n s ile E lo n g a tio n a t 30?°F Modulus Modulus S tr e n g th a t Break , M inutes PSI PSI PSI $ 20 80 180 30 1 10 3 50 2I 4 .7O 99 0 k$ 120 5li-0 3 0 0 0 870 60 llj.0 600 2200 6I 4 .O 80 llj.0 614-0 2 1 0 0 670 OPTIMUM CURB TIME - 50 minutes 73 COMPOUND S - 7 (HUNS 6 & l2j.) I n g r e d i e n t s p h r SB H -1500 1 0 0 .0 Z in c O x id e £ . 0 S t e a r i c A c id 1#5>0 BAP B la c k 3 5 .0 C i r c o s o l NS 15*0 CBS l . l i j . S u l f u r 2 .1 8 T o t a l 1 5 9 .8 2 PHYSICAL PROPERTIES Cur© T im e 100$ 300$ T e n s i l e E l o n g a t i o n a t 3 0 7 °P M odulus M odulus S t r e n g t h a t B re a k M in u te s P S I P S I P S I $ 1 5 100 300 20 lljjO 6 25 2 6 5 0 730 3 0 1 8 0 9 2 5 2 9 7 0 620 180 1050 3 0 6 0 5 8 0 60 180 1 0 5 0 2 5 6 0 5 1 0 OPTIMUM CURE TIME - 30 minutes 7 1 * COMPOUND S-8 (RUNS 7 & 15) I n g r e d i e n t s p h r SB R -1500 1 0 0 ,0 Z in c O x id e 5 * 0 S t e a r i e A c id 1*50 HAP B la c k 6 5 * 0 O i r c o s o l NS 15*0 CBS 0 .8 3 S u l f a r 1 .5 3 T o t a l 1 8 8 .8 6 PHYSICAL PROPERTIES C u re Time A t 30?°P M in u te s 100^ M odulus P S I 30($ M odulus PS I T e n s i l e S t r e n g t h P S I E l o n g a t i o n a t B re a k % 20 210 810 1250 590 30 260 1* 1 .0 0 2300 51*0 k$ 330 1800 2825 *190 6o 350 2020 2960 ij.60 80 360 2050 3100 '1*70 OPTIMUM CURE TIME - 50 minutes 75 COMPOUND S -9 (RUNS 8 & 1 6 ) I n g r e d i e n t s p h r SB R -1500 1 0 0 .0 Z in c O x id e 5 * 0 S t e a r i c A c id 1 .5 0 HAP B la c k 6 5 .0 C i r c o s o l IS 1 5 .0 CBS 1 , l k S u l f u r 2 .1 8 T o t a l 1 8 9 .8 2 PHYSICAL PROPERTIES C u re Tim e 1 0 0 $ 3 0 0 $ T e n s i l e E l o n g a t i o n a t 3 0 7 °P M o d u lu s M od u lu s S t r e n g t h a t B re a k M in u te s P S I P S I P S I $ 1 5 3 10 1680 2 7 0 0 5 0 0 2 0 i|£>0 2 2 1 0 3 1 0 0 !*M > 30 5 0 0 2 7 0 0 3 3 5 0 370 I4.5 5 5 0 3000 3it5 0 350 60 5 7 5 3 0 5 0 3 5 0 0 3^0 OPTIMUM CURE TIME - 30 minutes 76 GQMPOUHD S-10 (RUN 17) i Ingredients phr S B B -1500 1 0 0 .0 Z in c O x id e 5 * 0 j S t e a r i c A c id 1*50 | HAP B la e k £ 0 .0 j C i r e o s o l NS 1 0 .0 ' CBS 0 .7 0 S u l f u r 1 .2 6 T o t a l 168 .if6 p h y s ic a l p r o p e r t ie s C u re T im e 1 0 0 ^ 300$ T e n s i l e E l o n g a t i o n a t 3 0 7 °P M o d u lu s M odulus S t r e n g t h a t B re a k M in u te s P S I P S I P S I % 20 110 220 380 850 30 ii*o 520 1270 800 180 850 i 960 650 60 210 1000 2500 690 90 220 llljB 2760 650 OPTIMUM CURE TIME - 60 minutes 77 CQMPOUHD S - l l (EUH 1 8 ) phr SB R -1500 1 0 0 .0 Z in e O x id e 5 * 0 S t e a r i c A c id 1 .5 0 HAP B la c k S o .o G i r c o s o l FS 1 0 .0 CBS 1 .3 0 S u l f u r 2 .5 2 T o t a l 1 7 0 .3 2 PHYSICAL PROPERTIES C u re Tim e a t 3 0 7 °P M in u te s 100$ M odulus P S I 3©G$ M odulus P S I T e n s i l e S t r e n g t h P S I E l o n g a t i o n a t B re a k % 10 150 1*90 1320 720 20 3**0 151*0 2l*6o 3 ^0 30 U -9 0 2 5 6 0 2880 320 k$ 1*80 2670 2 8 7 0 330 6o lji*0 2700 21*70 290 OPTIMUM CURB TIME - 30 minutes 78 COMPOOT© S-12 (ROT 19) I n g r e d i e n t s SB R -1500 Z in c O x id e S t e a r i c A c id HAP B la c k G i r c o s o l M S CBS S u l f u r T o t a l C u re T im e a t 3 0 7 °F M in u te s 15 M o d u lu s P S I PHYSICAL PROPERTIES T e n s i l e r e n j P S I M odulus P S I - U n d e r - c u r e d — 20 80 I 4.60 1590 30 110 880 2060 1 * 5 110 1170 2220 6o 110 1200 2280 pfar 1 0 0 .0 5 * 0 1 .5 0 20.0 10.0 0 .9 7 1 .8 3 1 3 9 * 3 0 E l o n g a t i o n a t B re a k 910 750 700 680 OPTIMUM CURE TIME - i | . 0 minutes 79 COMPOUND S-13 (RUM 20) I n g r e d i e n t s p h r SB R -1500 1 0 0 .0 Z in c O x id e 5 - 0 S t e a r i e A c id 1*5© HAP B la c k 8 0 .0 C i r c o s o l M S 1 0 .0 CBS 0 .9 7 S u l f u r 1 .8 3 T o t a l 1 9 9 .3 0 PHYSICAL PROPERTIES Cur© Tim e 100$ 3 0 0 $ T e n s i l e E l o n g a t i o n a t 3 0 7 °F M odulus M o d u lu s S t r e n g t h a t B re a k M in u te s P S I P S I P S I , $ 15 530 1I 4 .IO 2110 310 20 670 1810 2780 280 30 800 2260 3150 270 k $ 950 2£M> 3160 2 i } X 3 60 990 2670 3030 220 OPTIMUM CURE TIME - minutes 80 COMPOUND S-ll}. (BUN 2 1 ) Ingredients SBB-1300 Zinc O xide Stearie Acid H A F Black C B S Sulfur phr Total 1 0 0 .0 5 * 0 1*5© 5 0 .0 0 .9 7 1 .8 3 1 5 9 * 3 0 P H Y S I C A L P R O P E R T I E S C ure T im e at 3 0 7 °F M inutes 1 0 0 $ M odulus P SI 300^ M odulus P S I Tensile Strength PSI 15 250 12ij.O 2500 20 360 2 0 0 0 3600 3 0 ii-30 2 l|£ 0 3 9 ^ 0 k s 5 0 0 2780 lj.120 6 0 5 0 0 2880 1^.070 at Break if-90 i|30 O P T I M U M C U B E T I M E - 35 minutes 8l COMPOUND S -1 5 (BUN 2 2 ) I n g r e d i e n t s p h r S B E -1500 1 0 0 .0 Z in c O x id e 5»© S t e a r i c A c id 1 . HAP B la c k £ 0 .0 C i r c o s o l NS 2 0 .0 CBS 0 .9 7 S u l f u r 1 ,8 3 T o t a l 1 7 9 .3 0 PHYSICAL PROPERTIES C u re T im e a t 3 0 7 °P M in u te s 100# M odulus P S I 3 0 0 $ M od u lu s P S I T e n s i l e S t r e n g t h P S I E l o n g a t i o n a t B re a k % 1 5 95 2 £0 6 8 5 870 20 130 6 20 1670 6 50 30 170 1010 2 5 5 0 6I +.0 45 200 1170 2 7 6 0 5 7 0 60 220 1330 2 8 8 0 5 7 0 OPTIMUM CURE TIME - i } . 0 minutes

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A study of ozone resistance of neoprene vulcanizates

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Study of various factors involved in the resistance of elastomeric vulcanizates to atmospheric conditions

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The effects of various factors on the ozone resistance of natural latex and milled latex vulcanizates

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Determination of a time-variable extraction coefficient for use with oleaginous seeds

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A study of rubber compounding by computer

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The separable programming problem and its application to the optimal formulation of elastomeric compounds

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A study of the Lamb equation in dynamic systems

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A study of antiozonant additives for butyl rubber compounds

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An investigation of the mechanism of pre-vulcanization of latex

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A study of tack of Nordel hydrocarbon rubber

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Ozone resistance of neoprene vulcanizates

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The phase behavior of cyclohexane-rich mixtures with water

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The GEL etchant concept for removing metal

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An experimental investigation of thixotropy and flow of thixotropic suspensions through tubes

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Electrochemical milling of stainless steel and Rene 41 by semisolid shaping tools

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Development of semi-solid etchants for chemical milling processes

Asset Metadata

Creator Morris, Donald Eugene (author)

Core Title A statistical study of the variables associated with the ozone cracking of elastomeric vulcanizates

Contributor Digitized by ProQuest (provenance)

Degree Master of Science

Degree Program Chemical Engineering

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag engineering, chemical,OAI-PMH Harvest

Language English

Advisor Partridge, Edward G. (committee chair), Lockhart, Frank J. (committee member), Rebert, Charles J. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c20-311775

Unique identifier UC11260285

Identifier EP41787.pdf (filename),usctheses-c20-311775 (legacy record id)

Legacy Identifier EP41787.pdf

Dmrecord 311775

Document Type Thesis

Rights Morris, Donald Eugene

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA