31 Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on March 21, 2018 | https://pubs.acs.org Publication Date: October 14, 1986 | doi: 10.1021/bk-1986-0322.ch031
Rubber Coatings for Fiberglass Protection in an Alkaline Environment P. Dreyfuss , R. D . Vargo , R. S. Miller , and R. Bright 1
CEMCOM
2
3
Research Associates, Inc., 9901 George Palmer Highway, Lanham, MD 20706
Glass is known to be r e a d i l y attacked by strong alkali. This was reaffirmed in the present study when samples of s t y l e 3701 Ε - g l a s s f a b r i c l o s t 90% of t h e i r original tensile strength after immersion in aqueous alkali at pH 13 and 80°C for 7 days. The purposes of this study were to gain some understanding of the relative importance of the factors that influence the d e g r a d a t i o n of g l a s s and coated g l a s s in alkaline environments and to use t h a t knowledge to develop a p r o t e c t i v e c o a t i n g . F a c t o r s evaluated included the c o m p o s i t i o n , surface area and and nature of the sur face of the glass. The effects of the nature, uniform ity, thickness and degree of bonding of glass coatings as well as different methods of applying coatings were considered. I t was shown t h a t w e l l - b o n d e d rubber coatings can lead to good protection of glass i n alka line environments.
G l a s s i s known t o be r e a d i l y a t t a c k e d by s t r o n g a l k a l i Q_). T h i s was r e a f f i r m e d i n t h e p r e s e n t study when samples o f s t y l e 3701 E - g l a s s f a b r i c f r o m B u r l i n g t o n G l a s s F a b r i c s Co. l o s t 90% o f t h e i r o r i g i n a l t e n s i l e s t r e n g t h a f t e r immersion i n aqueous a l k a l i a t pH 13 and 80°C f o r 7 days. The purposes o f t h i s s t u d y were t o g a i n some u n d e r s t a n d ing o f t h e r e l a t i v e importance o f t h e factors that influence the d e g r a d a t i o n o f g l a s s and c o a t e d g l a s s i n a l k a l i n e environments and t o u s e t h e knowledge g a i n e d t o d e v e l o p a c o a t i n g t h a t would p r o t e c t g l a s s i n a l k a l i n e environments.
'Current address: Michigan Molecular Institute, 1910 W. St. Andrews Road, Midland, Ml 48640 ^Current address: Institute of Polymer Science, The University of Akron, Akron, OH 44325 ^Current address: 1749 Dana Street, Crofton, M D 21114 0097-6156/86/0322-0349S06.00/0 © 1986 American Chemical Society
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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Experimental Materials. T a b l e I l i s t s t h e k i n d s a n d sources o f g l a s s f i b e r s , b a r s and s l i d e s u s e d i n t h i s s t u d y . E - g l a s s f a b r i c s were from B u r l i n g t o n G l a s s F a b r i c s Co. G l a s s beads were from P e t r a r c h Systems, Inc. o r P o t t e r s I n d u s t r i e s , I n c . 3 - A m i n o p r o p y l t r i e t h o x y s i l a n e as was o b t a i n e d f r o m P e t r a r c h S y s t e m s , I n c . The b u l k p o l y b u t a d i e n e was F i r e s t o n e ' s Diene 35 NFA, a n o n c r y s t a l l i z y i n g a n i o n i c p o l y b u t a d i e n e o f M « 1 5 0 , 0 0 0 a n d cis:trans: v i n y l (%) * 36:54:10. N a t u r a l rubber l a t e x e s ( 4 5 a n d 5 5 % s o l i d s ) were f r o m K i l l i a n L a t e x I n c . and SBR l a t e x P o l y s a r XE-404 was from P o l y s a r R e s i n s I n c . Dicumyl p e r o x i d e (DICUP R) was f r o m H e r c u l e s , I n c . The aqueous a l k a l i s o l u t i o n was p r e p a r e d u s i n g 0.008g (0.022 m o l e s ) / l sodium h y d r o x i d e , 3.45g (0.062 m o l e s ) / l p o t a s s i u m h y d r o x i d e and 0.48g (0.006 m o l e s ) / l c a l c i u m h y droxide. A c e t a t e s p l i c i n g s o l u t i o n was o b t a i n e d from B u r l i n g t o n G l a s s F a b r i c s Co. Alumina a c i d (80-200) mesh and c a l c i u m o x i d e were from F i s h e r S c i e n t i f i c Co. Boron o x i d e (99%) was from A l f a P r o d u c t s , Thiokol/Venton D i v i s i o n . W e i g h t L o s s S t u d i e s . G l a s s samples were r i n s e d s u c c e s s i v e l y w i t h t o l u e n e a n d a c e t o n e a n d d r i e d i n an oven a t 80°C f o r 10 min. G l a s s s a m p l e s f o r t e s t i n g i n water were p l a c e d i n a l a r g e S o x h l e t e x t r a c t o r ( f r o m a 120 mm j o i n t ) and e x t r a c t e d w i t h d i s t i l l e d water f o r 24 h r s . b e f o r e d r y i n g and r e w e i g h i n g . The weight l o s s was the d i f f e r e n c e b e t w e e n t h e i n i t i a l weight and the f i n a l w e i g h t . S i n c e none o f t h e s a m p l e s l o s t a p p r e c i a b l e w e i g h t , t h i s method was a l s o u s e d f o r washing samples f o r weight l o s s s t u d i e s a f t e r immersion i n alkali. A f t e r c o o l i n g , weighed samples f o r t e s t i n g i n a l k a l i were p l a c e d i n p r e c l e a n e d 1000 m l p o l y p r o p y l e n e b o t t l e s f i t t e d w i t h d i v i d e r s from porous p o l y p r o p y l e n e when a p p r o p r i a t e . Beads, chopped f i b e r s a n d powders were p l a c e d i n T e f l o n e x t r a c t i o n t h i m b l e s b e f o r e p u t t i n g i n t o t h e b o t t l e s . Long f i b e r s were wrapped around s p e c i a l p o r o u s p o l y p r o p y l e n e h o l d e r s a s l o n g a s the b o t t l e s and then put i n t o the b o t t l e s . The b o t t l e s w e r e t h e n f i l l e d w i t h the aqueous a l k a l i s o l u t i o n , c l o s e d w i t h T e f l o n l i n e d caps and p l a c e d f o r 7 days i n a c i r c u l a t i n g w a t e r b a t h a t 80°C. The s a m p l e s were removed, t h o r o u g h l y r i n s e d w i t h w a t e r , d r i e d o v e r n i g h t i n an a i r oven a t 80°C, c o o l e d i n a d e s s i c a t o r and reweighed. Dumbbells from c u r e d rubber samples were s i m i l a r l y t e s t e d . A l k a l i D u r a b i l i t y T e s t s o f G l a s s F i b e r s and G l a s s F a b r i c s . These t e s t s were c a r r i e d o u t u s i n g a m o d i f i c a t i o n o f B u r l i n g t o n T e s t P r o c e d u r e FP-017. For d u r a b i l i t y t e s t s g l a s s f i b e r s were t r e a t e d i n t h e same way a s f o r w e i g h t l o s s s t u d i e s . C a r e was t a k e n t o run t e n s i l e t e s t s o n l y on t h o s e p o r t i o n s o f the f i b e r , which had not b e e n b e n t a r o u n d t h e edges o f the h o l d e r . Samples o f g l a s s f a b r i c 27.9 cm. ( 1 1 " ) l o n g ( i n the warp d i r e c t i o n ) and 15.2 cm. (6") wide ( i n t h e f i l l d i r e c t i o n ) were c u t from r o l l s o f f a b r i c and c o a t e d as d e s i r e d . The p r e p a r e d c l o t h specimens were p l a c e d i n heavy-duty 4.5 -mil t h i c k 24.13 χ 40.64 cm Kapak h e a t - s e a l a b l e pouches. Enough a l k a l i s o l u t i o n t o f i l l the bag was added, the pouch was h e a t - s e a l e d u s i n g a S c o t c h Pak Pouch S e a l e r and p l a c e d i n the c i r c u l a t i n g water b a t h a t 80°C f o r 7 d a y s . The f a b r i c was r e m o v e d from t h e a l k a l i s o l u t i o n , r i n s e d w i t h w a t e r , d r i e d o v e r n i g h t i n a vacuum oven a t 60°C, and p r e p a r e d f o r t e n s i l e t e s t i n g .
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Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
2
Slides
Soda Lime
18.3 0.07 0.14 1.4 1.6 0.035 0.04 0.033 0.10 0.07 0.35
water; alkali: water: alkali: water: alkali: water: alkali: water: alkali: water: alkali:
% Wt. Loss
No change S l i g h t Fogging S t i f f , n o t much change S o f t and wooly No change No change No change Uniform fogging Fogged, e x t r e m e l y discolored Uniform fogging
Appearance
A f t e r immersion i n t h e medium shown i n column 4 a c c o r d i n g t o t h e procedure g i v e n i n t h e e x p e r i m e n t a l section. Ε-glass were random s i z e s u n s u i t a b l e f o r p e e l t e s t s . P y r e x and q u a r t z b a r s were 127 χ 25 χ 6.5mm. Alkali-resistant glass. Pre-cleaned microscope s l i d e s .
Kimble
F i v e P o i n t s G l a s s Co.
2
Bars
Quartz
4
F i v e P o i n t s G l a s s Co.
2
Cem-FIL Corp*
PPG I n d u s t r i e s * I n c .
B u r l i n g t o n G l a s s F a b r i c s Co.
Source
Bars
Fibers
Bars
Fibers
Form
Weight Loss Comparison f o r D i f f e r e n t G l a s s e s
Pyrex
Ε
Glass
Table I .
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Tensile Testing. T e n s i l e t e s t s were run on an I n s t r o n 1000 u s i n g a 5.08 cm ( 2 i n c h ) guage l e n g t h a n d a s p e e d o f 12.7 cm ( 5 inches)/min. The p r o c e d u r e s i n B u r l i n g t o n Test Procedure FP-015 (ASTM-D-579) were f o l l o w e d . A t l e a s t 5 specimens o f each sample were tested. F a b r i c t e s t s r e s u l t s a r e q u o t e d f o r t h e warp d i r e c t i o n o n l y . The p e r c e n t r e t e n t i o n o f t e n s i l e s t r e n g t h was c a l c u l a t e d from t h e e q u a t i o n : % r e t e n t i o n « (PA^ NA^ 100 where F^ and FJJA s t r e n g t h a f t e r and b e f o r e a l k a l i immersion, r e s p e c t i v e l y . S i l a n e Treatment. G l a s s b a r s , f i b e r s o r f a b r i c were soaked 5 min i n s t i r r e d s o l u t i o n s ( 0 . 5 , 1.0, 1.5, o r 2.0%) o f 3-aminopropylt r i e t h o x y s i l a n e i n 95% e t h a n o l , then f o r 10 min. i n 95% e t h a n o l , and f i n a l l y f o r 1 min. i n a b s o l u t e e t h a n o l . The g l a s s was h e a t e d o v e r n i g h t i n a vacuum oven a t 110°C t o form a p o l y s i l o x a n e l a y e r bonded to the g l a s s ( 2 ) . Latex Treatment. A t y p i c a l procedure f o r l a t e x treatment i s shown s c h e m a t i c a l l y i n F i g u r e 1. D e t a i l s o f the procedure a r e g i v e n i n U.S. P a t e n t A p p l i c a t i o n S e r i a l No. 06/701,747, f i l e d 2/14/85. Blowers were used t o d i s l o d g e any l a t e x which might e x i s t as "window p a n e " l i k e f i l m s between b u n d l e s o f f i b r e s i n t h e f a b r i c . The tem p e r a t u r e i n the f i r s t two d r y e r s was m a i n t a i n e d a t 75-85°C, too l o w a t e m p e r a t u r e t o c u r e t h e l a t e x d u r i n g the d r y i n g t i m e . The temper a t u r e i n the t h i r d d r y e r was t y p i c a l l y 120°C and c u r i n g o f the r u b b e r was c o n t i n u e d a t t h a t t e m p e r a t u r e f o r 30 m i n u t e s . M i c r o s c o p y r e v e a l e d t h a t t h e f i r s t d i p r e s u l t s i n rubber p e n e t r a t i o n o f t h e f i b e r b u n d l e b u t d o e s n o t c o a t t h e b u n d l e . The second and t h i r d d i p s p r o d u c e c o a t i n g s o f about 10 micrometers each. F i g u r e 2 i s a schematic r e p r e s e n t a t i o n o f t h e manner i n which the c o a t i n g s d e p o s i t on t h e f i b e r s i n the f i b e r b u n d l e . P e e l T e s t s . Ε-glass p l a t e s (0.635 χ 20.32 χ 20.32 cm, 1/4 χ 8 χ 8") were c u t t o ~ 2 . 54 χ 7.62cm (1 χ 3") u s i n g a g l a s s saw. The b a r s w e r e c l e a n e d b y b o i l i n g i n 2% M i c r o s o l u t i o n ( a l a b o r a t o r y c l e a n e r from I n t e r n a t i o n a l P r o d u c t s C o r p . ) , washed f o r 48 h r s . w i t h d i s t i l l e d w a t e r i n a S o x h l e t e x t r a c t o r , d r i e d f o r 2 h r s . i n an a i r oven a t 150°C and s t o r e d i n a d e s s i c a t o r over P2O5 u n t i l used. P e e l t e s t s p e c i m e n s f o r t e s t i n g w i t h o u t immersion i n the aqueous a l k a l i were p r e p a r e d a n d t e s t e d a c c o r d i n g t o p r o c e d u r e s p r e v i o u s l y d e s c r i b e d ( 3-5) . T h u s , d i c u m y l p e r o x i d e was mixed i n t o p o l y b u t a d i e n e o n a n open m i l l . B e f o r e bonding, the e l a s t o m e r was p r e s s e d i n t o a t h i n l a y e r (-0.2 mm) b y p r e m o l d i n g f o r 1 h r . a t 65°C, then p r e s s e d i n t o a s h e e t o f c o t t o n c l o t h and a g a i n premolded f o r 1 h r . a t 65°C. The c l o t h b a c k e d l a y e r was t h e n p r e s s e d a g a i n s t t h e c l e a n e d g l a s s s l i d e s f o r 2 h r . a t 150°C i n a PHI p r e s s a t a p r e s s u r e o f -6 p s i / 5 i n ram i n o r d e r t o c u r e the e l a s t o m e r . The t h i c k n e s s o f the elastomer i n t e r l a y e r i n t h e r e s u l t i n g cloth-elastomer-glass s a n d w i c h was ~0.2mm. 180° P e e l i n g t e s t s were c a r r i e d out on s t r i p s o f c l o t h b a c k e d e l a s t o m e r l a y e r a f t e r t r i m m i n g them t o a u n i f o r m w i d t h on the g l a s s o f 2 cm. The e l a s t o m e r was p e e l e d o f f the g l a s s a t a c o n s t a n t r a t e , 0.5 cm/min (0.0083 cm/sec) u s i n g a t a b l e model I n s t r o n . The work o f a d h e s i o n , W^, was c a l c u l a t e d from the e q u a t i o n • 2P/w, where Ρ i s t h e time average p e e l f o r c e and w i s the w i d t h of t h e d e t a c h i n g l a y e r . Samples f o r t e s t i n g i n a l k a l i were c u r e d between a c l o t h backed r u b b e r s h e e t a n d a n u n b a c k e d r u b b e r s h e e t u s i n g t h e same c u r i n g c o n d i t i o n s and t h e n were trimmed i n two s t a g e s . I n t h e f i r s t s t a g e t h e s p e c i m e n s were c u t a p a r t so t h a t the g l a s s b a r s were c o m p l e t e l y
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Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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E
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31.
Fiberglass Protection in an Alkaline Environment
DREYFUSS ET AL.
APPLY SILANE FINISH TO GLASS I . DIP INTO HIGH SOLIDS SBR L A T E X
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•
I SQUEEZE TO REMOVE EXCESS AND IMPREGNATE
LATEX
GLASS
DRY IN FORCED AIR DRYER I DIP INTO HIGH NATURAL RUBBER
SOLIDS
»
SQUEEZE TO IMPREGNATE
,
I
DRY .
LATEX
FURTHER SCRIM
,
AGAIN
1 ' DIP IN THIRD RUBBER LATEX (NATURAL RUBBER)
»
DRY APPLY
F i g u r e 1.
AND
CURE
TALC OR STARCH (OPTIONAL)
Flow sheet showing s t e p s i n c o a t i n g p r o c e s s .
UNCOATED GLASS BUNDLE
F i g u r e 2.
COATED
GLASS
Schmatic v i e w o f g l a s s f i b e r
BUNDLE
bundles.
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embedded i n the c u r e d e l a s t o m e r . Care was taken t o i n s u r e t h a t t h e r e were no h o l e s through the e l a s t o m e r t o the g l a s s , because a l k a l i can s e e p t h r o u g h h o l e s , degrade the g l a s s , and i n v a l i d a t e the measure ments. The t h i c k n e s s o f the e l a s t o m e r was 1 mm o r more on a l l s i d e s e x c e p t t h e one w i t h the c l o t h backed e l a s t o m e r , where t h e e l a s t o m e r t h i c k n e s s was 0.4-0.6 mm. The samples were t r e a t e d w i t h a l k a l i as d e s c r i b e d a b o v e , removed from the a l k a l i , and d r i e d o v e r n i g h t i n a vacuum o v e n a t 60°C. For p e e l t e s t s , s t r i p s o f c l o t h backed e l a s t o m e r were o b t a i n e d by t r i m m i n g as above. The s t r e n g t h o f the r u b b e r i m p r e g n a t e d c o t t o n c l o t h b a c k i n g was r e t a i n e d a f t e r a l k a l i t r e a t m e n t , even though u n t r e a t e d c l o t h d i s i n t e g r a t e d under t h e same c o n d i t i o n s . F i r e s t o n e ' s Diene 35 NFA was the rubber used f o r t h e s e s t u d i e s . 0.05% p a r t s per hundred o f rubber o f d i c u m y l p e r o x i d e was used f o r c u r i n g . C o a t i n g w i t h B u l k P o l y b u t a d i e n e . Ε-glass f a b r i c was embedded i n F i r e s t o n e ' s D i e n e 35 NFA u s i n g p r o c e d u r e s v e r y s i m i l a r t o those u s e d t o p r e p a r e p e e l t e s t specimens. Rubber, which had been m i l l m i x e d w i t h 0.05% d i c u m y l p e r o x i d e , was p r e m o l d e d b e t w e e n M y l a r s h e e t s t o the d e s i r e d t h i c k n e s s ( 0 . 3 0 8 , 0.151, o r 0.100 cm) and s i z e (- 30.5 χ 18 cm) b y m o l d i n g f o r 1 hour a t 60°C. and 40,000 l b s / 5 " ram. F a b r i c was c u t s o t h a t the f i n a l s i z e was a t l e a s t one i n c h s m a l l e r t h a n t h e r u b b e r s h e e t s i n a l l d i r e c t i o n s . A sandwich was made f r o m t h e f a b r i c a n d two p r e m o l d e d rubber s h e e t s o f the same t h i c k n e s s and about h a l f the t o t a l t h i c k n e s s o f the f i n a l sandwich. The s a n d w i c h was c u r e d i n a p r e s s f o r 2 h o u r s a t 150°C and 5000 l b s / 5 " ram. I n t h e c u r e d specimen the f a b r i c was embedded i n the c e n t e r o f t h e m o l d e d specimen (0.15 -0.40 i n t h i c k ) . Samples were immensed i n a l k a l i b e f o r e c u t t i n g t o s i z e f o r t e n s i l e t e s t s . T h i n n e r c o a t i n g s on f a b r i c s and f i b e r s were p r e p a r e d by d i p p i n g t h e f a b r i c o r f i b e r s i n t o a s o l u t i o n c o n t a i n i n g 500 ml hexane, 50 g p o l y b u t a d i e n e and 0.02 g d i c u m y l p e r o x i d e . Excess s o l u t i o n was s q u e e z e d o f f b y p a s s i n g t h e f a b r i c o r f i b e r s between r o l l e r s , t h e h e x a n e was removed b y e v a p o r a t i o n , and t h e rubber was c u r e d f o r 2 hours i n a vacuum oven a t 150°C. M i c r o s c o p y . A L e i t z O r t h o p l a n microscope f i t t e d w i t h a P o l a r o i d Land Camera was used t o examine samples a t low m a g n i f i c a tion. Scanning e l e c t r o n m i c r o g r a p h s were t a k e n w i t h an ISI-SS40. R e s u l t s and D i s c u s s i o n Many o f t h e f a c t o r s t h a t i n f l u e n c e the d e g r a d a t i o n o f g l a s s i n an a l k a l i n e e n v i r o n m e n t a r e o b v i o u s . They i n c l u d e the c o m p o s i t i o n o f t h e g l a s s , t h e s u r f a c e a r e a o f t h e g l a s s , a n d t h e n a t u r e o f the s u r f a c e o f the g l a s s . When c o a t i n g s are a p p l i e d t o the g l a s s , a d d i t i o n a l f a c t o r s need t o be c o n s i d e r e d a l s o . These a d d i t i o n a l f a c t o r s i n c l u d e t h e u n i f o r m i t y o f the c o a t i n g , the i n f l u e n c e o f the t h i c k n e s s o f t h e c o a t i n g , the degree o f bonding between the c o a t i n g and the g l a s s , and the e f f e c t o f d i f f e r e n t methods o f a p p l y i n g the c o a t ing. A comprehensive c o n s i d e r a t i o n o f each o f these f a c t o r s i s b e y o n d t h e s c o p e o f t h i s paper but each o f them was examined i n a t l e a s t a p r e l i m i n a r y way. The c o n c l u s i o n s o f t h i s study a r e based on w e i g h t l o s s s t u d i e s , m i c r o s c o p y , p e e l t e s t measurements and t e n s i l e p r o p e r t i e s b e f o r e and a f t e r immersion i n t h e aqueous a l k a l i solution.
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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S t u d i e s on G l a s s A l o n e . Weight l o s s comparisons f o r d i f f e r e n t k i n d s o f g l a s s a f t e r i m m e r s i o n i n w a t e r and a l k a l i a r e g i v e n i n T a b l e I . The d a t a showed t h a t a l l t h e g l a s s e s l i s t e d were r e a s o n a b l y s t a b l e i n w a t e r , t h a t f i b e r s were more s e v e r e l y degraded then b a r s , e s p e c i a l l y i n a l k a l i n e s o l u t i o n s and t h a t o f t h e g l a s s e s t e s t e d , Ε-glass and soda l i m e g l a s s were t h e most s e v e r e l y c o r r o d e d by t h e a l k a l i . The d i f f e r e n c e among t h e k i n d s o f g l a s s can be p a r t i a l l y e x p l a i n e d i n t e r m s o f t h e r e l a t i v e s t a b i l i t y i n water and a l k a l i o f t h e v a r i o u s m a t e r i a l s c o m p r i s i n g t h e g l a s s e s . Some t y p i c a l f o r m u l a t i o n s a r e g i v e n i n Table I I ( 6 - 8 ) . T a b l e I I . T y p i c a l Weight % C o m p o s i t i o n o f G l a s s e s ( 6 - 8 ) Oxide
Si0 Na 0 CaO A1 0 B 0 MgO K 0 Zr0 Li 0
Glass
2
2
3
3
2
Pyrex 80.5 3.8
2
Ε 54.5 1+ 17.0 14.5 8.5 4.5 4.0
2
2
1
AR 70.3 11.8
Quartz 100
2.2 12.9
Soda Lime 72 14 13 1
0.4 16.1 1
2
2
1
Only t h e major o x i d e s ( 1 % o r g r e a t e r ) are l i s t e d . Most g l a s s e s a l s o h a v e s m a l l amounts o f o t h e r m e t a l o x i d e s such as Fe 03» T i 0 , Mn Û3, e t c . A l k a l i - r e s i s t a n t glass. 2
2
2
2
A comparison o f the r e s u l t s i n Table I w i t h the compositions i n T a b l e I I s u g g e s t s t h a t h i g h c o n c e n t r a t i o n s o f CaO and A 1 0 l e a d t o decreased d u r a b i l i t y i n a l k a l i . T h i s i s n o t s u r p r i s i n g when t h e r e s u l t s o f % w e i g h t l o s s s t u d i e s on t h e s e m e t a l o x i d e s a l o n e and t h e i r known c h e m i s t r y a r e c o n s i d e r e d . A l 0 3 , when exposed t o t h e s t a n d a r d a l k a l i n e c o n d i t i o n s , l o s t 8.3% by w e i g h t . A 1 0 , when h y d r a t e d , i s a m p h o t e r i c , i s s o l u b l e i n s t r o n g a l k a l i s , and forms compounds l i k e N a A 1 0 o r C a ( A 1 0 ) . Thus t h e h i g h c o n c e n t r a t i o n o f A1 0 i n Ε-glass c a n a t l e a s t p a r t i a l l y account f o r t h e observed weight l o s s . ( B 0 was t o t a l l y s o l u b l e under t h e u s u a l a l k a l i n e c o n d i t i o n s and when h y d r a t e d , i n a c i d i c . However, t h e s t a b i l i t y o f P y r e x g l a s s suggests t h a t boron i s p r e s e n t i n g l a s s n o t as B 0 b u t i n some f o r m t h a t i s n o t r e a d i l y a t t a c k e d by a l k a l i . ) CaO, when exposed t o t h e s t a n d a r d a l k a l i n e c o n d i t i o n s , gained 13.3% by w e i g h t . T h i s i s u n d e r s t a n d a b l e b e c a u s e CaO c a n r e a c t w i t h water t o form Ca(0H) and w i t h d i s s o l v e d C 0 t o form CaC0 . Both p r o d u c t s have h i g h e r m o l e c u l a r w e i g h t s t h a n CaO. I n o r d e r t o account f o r t h e o b s e r v e d w e i g h t l o s s w i t h Ε-glass and even more so w i t h soda l i m e g l a s s , i t must be assumed t h a t e i t h e r t h e s e p r o d u c t s s l o w l y d i s s o l v e i n t h e a l k a l i o r e l s e they a r e washed o f f t h e s u r f a c e o f t h e g l a s s . ( A g a i n t h e N a 0 p r e s e n t i n s i g n i f i c a n t q u a n t i t i e s i n soda l i m e c a n not a c c o u n t f o r t h e s e v e r e w e i g h t l o s s o b s e r v e d w i t h soda lime 2
3
2
2
2
2
2
3
2
3
2
3
2
2
2
3
2
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
3
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POLYMERIC MATERIALS FOR CORROSION CONTROL
g l a s s , b e c a u s e AR ( a l k a l i - r e s i s t a n t ) g l a s s a l s o c o n t a i n s much N a 0 and i s e s p e c i a l l y f o r m u l a t e d t o be and indeed i s o b s e r v e d t o be more resistant to a l k a l i ) . T e n s i l e measurements o f t h e E - g l a s s and A R - g l a s s f i b e r s showed t h a t a l t h o u g h t h e Ε-glass f i b e r s w e r e s t r o n g e r i n i t a l l y than t h e A R - g l a s s f i b e r s , t h e A R - g l a s s retained i t s strength b e t t e r i n the a l k a l i . E - g l a s s f i b e r s were t o o weak t o t e s t a f t e r immersion i n t h e a l k a l i , w h e r e a s A R - g l a s s f i b e r s showed 1 9 % r e t e n t i o n o f i n i t i a l strength. The much g r e a t e r weight l o s s observed w i t h E - g l a s s f i b e r s r e l a t i v e t o Ε-glass b a r s s u g g e s t s t h a t exposed s u r f a c e area p l a y s an i m p o r t a n t r o l e i n d u r a b i l i t y i n a l k a l i n e s o l u t i o n s . The e f f e c t o f s u r f a c e a r e a was examined by d e t e r m i n i n g t h e p e r c e n t weight l o s s o f s o d a l i m e b e a d s o f d i f f e r e n t b u t known d i a m e t e r a f t e r immersion i n the a l k a l i . A s shown i n F i g u r e 3 t h e weight l o s s i n c r e a s e d l o g a r i t h m i c a l l y w i t h t h e square o f t h e beads' d i a m e t e r s , i . e . o f t h e i r surface area. We c o n c l u d e d t h a t t h e l a c k o f d u r a b i l i t y i n a l k a l i o f E - g l a s s i s r e l a t e d t o i t s c h e m i c a l c o m p o s i t i o n and t h a t a c o a t i n g was needed t o p r o t e c t t h e g l a s s . A s u i t a b l e c o a t i n g s h o u l d b o t h reduce t h e s u r f a c e a r e a e x p o s e d t o t h e a l k a l i and p r e v e n t c o n t a c t between t h e d e g r a d a b l e components i n t h e g l a s s and t h e a l k a l i . S t u d i e s on Coated G l a s s . G l a s s beads, f i b e r s , and f a b r i c s a r e c o m m e r c i a l l y a v a i l a b l e w i t h v a r i o u s p o l y s i l o x a n e c o a t i n g s , which a r e c h e m i c a l l y b o n d e d t o t h e g l a s s t h r o u g h t h e s i l a n o l g r o u p s (_2). U s u a l l y t h e p o l y s i l o x a n e c o a t i n g s c o n t a i n o t h e r f u n c t i o n a l groups, which can serve as bonding s i t e s f o r o t h e r c o a t i n g s . I t was o f i n t e r e s t t o compare t h e degree t o which t h e s e p o l y s i l o x a n e s r e n d e r e d the g l a s s c o r r o s i o n r e s i s t a n t t o a l k a l i n e s o l u t i o n . Weight l o s s d a t a g i v e n i n T a b l e I I I , showed s i g n i f i c a n t d i f f e r e n c e s . P o l y s i l o x a n e s w i t h a l o n g a l k y l group l i k e o c t a d e c y l gave c o a t i n g s t h a t r e s u l t e d i n a s i g n i f i c a n t i n c r e a s e i n t h e d u r a b i l i t y o f t h e coated g l a s s i n a l k a l i . S h o r t e r a l k y l s u b s t i t u e n t s l i k e e t h y l , d i m e t h y l and v i n y l w e r e d e l e t e r i o u s a n d most p o l a r s u b s t i t u e n t s t e s t e d ( g l y c i d o x y - , m e t h a c r y l o x y - ) seemed t o encourage w e i g h t l o s s . The b a s i c 3-aminop r o p y l g r o u p gave some p r o t e c t i o n . These d a t a suggest t h a t c o n t i nuous n o n p o l a r h y d r o c a r b o n c o a t i n g s might p r o t e c t t h e g l a s s and t h a t a p o l y s i l o x a n e c o a t i n g w i t h 3-aminopropyl-groups t o promote bonding w i t h t h e h y d r o c a r b o n l a y e r (2,3) s h o u l d n o t be d i s a d v a n t a g e o u s . S t u d i e s w i t h Rubber C o a t i n g s . The a b o v e s u g g e s t i o n s w e r e v e r i f i e d i n s t u d i e s w i t h rubber c o a t i n g s on g l a s s p l a t e s , f i b e r s and f a b r i c s . 180° p e e l t e s t s on E - g l a s s p l a t e s showed t h a t w i t h o r w i t h out p r i o r surface coating o f the p l a t e s with the aminopolysiloxane, t h e r e was no d e c r e a s e i n t h e a d h e s i o n between t h e g l a s s and p e r o x i d e - c u r e d p o l y b u t a d i e n e c o a t i n g s . The r e s u l t s a r e summarized i n F i g u r e 4. Most samples f a i l e d c o h e s i v e l y i n t h e r u b b e r l a y e r . The s t r e n g t h o f t h e s a m p l e s t h a t were n o t exposed t o a l k a l i i n c r e a s e d s t e a d i l y w i t h t h e percent o f 3-aminospropytriethoxysilane (AS) i n the s o l u t i o n used t o t r e a t t h e g l a s s . The s t r e n g t h s o f samples e x p o s e d t o a l k a l i were e s s e n t i a l l y c o n s t a n t a t c o n c e n t r a t i o n s o f 1% AS a n d a b o v e . B a r s t h a t were n o t c o a t e d w i t h t h e p o l y s i l o x a n e f a i l e d a d h e s i v e l y and t h e s c a t t e r i n t h e r e s u l t s (± ~ 35%) r e f l e c t e d t h e f a c t t h a t t h e s u r f a c e o f t h e b a r s was n o t as smooth as t h e s u r f a c e o f m i c r o s c o p e s l i d e s a n d o t h e r b a r s used i n p r e v i o u s s t u d i e s (3-5).
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2
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
DREYFUSS ET AL.
Fiberglass Protection in an Alkaline Environment
θ
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(%) wt. LOSS 4
1 Mill
1
1 1 1 1 1 III
I
I
1 1 1 M III
100 d
2
x
I0"
3
1
1000 (/im
2
1 11 Tm
)
F i g u r e 3. E f f e c t o f soda l i m e bead s i z e on p e r c e n t weight l o s s a f t e r immersion i n a l k a l i f o r 7 days a t 80°C.
1200
>
, No / Alkali Λ* Cohesive 800 W
A
Alkali χ Cohesive
X
(N/m)
A
400
/o
/
o Adhesive 0
i
%
AS
1
•
2.0
1.0 in
EtOH
F i g u r e 4. P e e l t e s t r e s u l t s on Ε-glass p l a t e s as a f u n c t i o n o f p e r c e n t o f 3 - a m i n o p r o p y l t r i e t h o x y s i l a n e i n s o l u t i o n used t o treat plates, x: r e s u l t s a f t e r immersion i n a l k a l i f o r 7 days a t 80°C. o: i n i t i a l r e s u l t s .
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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Table I I I .
S t u d i e s w i t h S i l a n e Coated Soda Lime G l a s s
F u n c t i o n a l Group on S i l i c o n CH (CH )i7 NH (CH ) Uncoated CH -CHCH CH CH ) Uncoated 0 3
1
Size Mesh 70-140 70-140 70-140 70-140 70-140 70-140 325
2
2
2
3
2
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3
3
2
2
CH CHCH 0(CH ) 2
2
2
3
CH -C(CH )CO(CH ) 2
3
2
3
145 145 145 145 145 145 25
Beads
% Wt. Loss in A l k a l i 0.86 2.08 2.27 3.18 3.58 4.88 4.50
325
25
5.87
325
25
10.89
1
S i l a n e c o a t i n g s a r e c h e m i c a l l y bonded t o g l a s s t h r o u g h t h e s i l a n o l g r o u p s on t h e g l a s s s u r f a c e . The c o a t i n g s a r e o f t e n p r e p a r e d by r e a c t i n g a t r i a l k o x y a l k y l s i l a n e , ( R 0 ) S i R , w i t h t h e g l a s s and then h e a t i n g t o form a p o l y s i l o x a n e l a y e r w i t h t h e f u n c t i o n a l group from R', i f any, i n t h e s u r f a c e and a v a i l a b l e f o r f u r t h e r r e a c t i o n (2.). A d i a l k o x y d i a l k y l s i l a n e , ( R O ) S i R , can be used i n t h e same way. I f R i s C H and t h e s i l a n e i s ( R O ) S i R ' , e.g., the p o l y s i l o x a n e l a y e r w i l l have two C H groups and fewer bonds t o t h e g l a s s s u r f a c e . f
3
,
2
2
?
3
2
2
3
A R - f i b e r coated w i t h t h e same p o l y s i l o x a n e and passed through a hexane s o l u t i o n c o n t a i n i n g p o l y b u t a d i e n e and p e r o x i d e b e f o r e c u r i n g , showed 100% s t r e n g t h r e t e n t i o n i n a l k a l i n e s o l u t i o n . E - g l a s s f a b r i c embedded i n p e r o x i d e - c u r e d p o l y b u t a d i e n e showed n e a r l y 100% r e t e n t i o n o f o r i g i n a l strength f o r polybutadiene t h i c k n e s s e s o f 1 mm o r more. The s t r e n g t h t y p i c a l l y o b s e r v e d f o r #3701 g r e i g e goods as r e c e i v e d was 26.8-29.1 kN/m (153-166 l b s . p e r i n c h w i d t h ) . Strength r e t e n t i o n i n t h e a l k a l i was a t most 10%. P o l y b u t a d i e n e coated s p e c i m e n s h a d i n i t i a l s t r e n g t h s o f 16.6-19.8 kN/m (95-113 l b s p e r i n c h w i d t h ) , a n d s t r e n g t h r e t e n t i o n i n t h e a l k a l i was 80-100% f o r c o a t i n g s 1 mm t h i c k o r g r e a t e r . ( T h e s t r e n g t h o f t h e composite v a r i e d w i t h the t h i c k n e s s o f the polybutadiene. Thicker coatings gave weaker o v e r a l l composite s t r e n g t h s . ) From l a t e x e s , c o a t i n g s as t h i n a s 0.03 mm gave good p r o t e c t i o n . T y p i c a l d a t a i s shown i n F i g u r e 5. M u l t i p l e d i p p i n g s were n e c e s s a r y , s i n c e t h e f i r s t d i p gave o n l y p e n e t r a t i o n o f t h e f i b e r b u n d l e a n d no c o a t i n g . The f i r s t l a t e x d i p i s p r e f e r a b l y i n t o a l a t e x o t h e r than n a t u r a l rubber ( e . g . SBR l a t e x ) b e c a u s e good a d h e s i o n b e t w e e n t h e g l a s s and a c o a t i n g from n a t u r a l rubber l a t e x i s n o t o b t a i n e d . Acknowledgments S a m p l e s o f v a r i o u s E - g l a s s f a b r i c s and f i b e r s from B u r l i n g t o n G l a s s F a b r i c s Co., o f Diene 35 NFA from F i r e s t o n e T i r e and Rubber Co. and o f d i c u m y l p e r o x i d e , DICUP R, f r o m H e r c u l e s , I n c . a r e g r a t e f u l l y a c k n o w l e d g e d . Rubber l a t e x e s were k i n d l y s u p p l i e d by K i l l i a n L a t e x I n c . a n d P o l y s a r R e s i n s , I n c . Thanks a r e g i v e n t o J a n i n e R i z e r f o r h e l p w i t h t e n s i l e s t r e n g t h measurements.
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
31.
DREYFUSS ET AL.
Fiberglass Protection in an Alkaline Environment THICKNESS
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10
100
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Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on March 21, 2018 | https://pubs.acs.org Publication Date: October 14, 1986 | doi: 10.1021/bk-1986-0322.ch031
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Δ Pl*2, 70°C, 30min. O PI #2,150°C, 15 min. • P I * 4 , I 3 0 ° C , 10 min. ·
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2 of DIPS F i g u r e 5. P e r c e n t r e t e n t i o n o f s t r e n g t h o f l a t e x c o a t e d #3701 f a b r i c w i t h 3 - a m i n o p r o p y l p o l y s i l o x a n e c o a t i n g , a f t e r immersion i n a l k a l i f o r 7 days a t 8 0 ° C , as a f u n c t i o n o f number o f d i p s i n l a t e x , k i n d o f l a t e x , and c u r i n g c o n d i t i o n s . PI#2 i s K i l l i a n 500 c l e a r p o l y i s o p r e n e l a t e x - Cure 2; PI M i s K i l l i a n 500 c l e a r p o l y i s o p r e n e l a t e x - Cure 4; PI#2 and PI//4 were r e c e i v e d from K i l l i a n as p a r t i a l l y c u r e d r e s i n s . SBR i s P o l y s a r XE-432 s t y r e n e - b u t a d i e n e l a t e x . The temperature and time o f c u r e a r e c i t e d a f t e r each l a t e x . I
NO.
Literature Cited 1. 2. 3. 4. 5. 6. 7. 8.
Boyd, D. C . ; Thompson, D. A. Encyclopedia Chem. Technol. 1980, 11, p. 843. Plueddemann, E. P. "Silane Coupling Agents"; Plenum Press:New York, 1982. Eckstein, Y . ; Dreyfuss, P. J . Adhesion 1983, 15, 193-202. Ahagon, Α . ; Gent, A. N. J. Polym. Sci.:Polym. Phys. Ed. 1975, 13, 1285-1300. Liang, F . ; Dreyfuss, P. J. Appl. Polym. Sci. 1984, 29, 31473159. Anledter, H. F. Encyclopedia Polym. Sci. and Technol. 1967, 6, p. 634. Mack, Jr., E.; Garrett, A. B.; Haskins, J . F.; Verhoek, F. H. "Textbook of Chemistry"; Ginn and Co.:New York, 1949; p. 760. Hannant, D. J. "Fibre Cements and Fibre Concretes"; John Wiley & Sons:New York, 1978; p. 100.
Dickie and Floyd; Polymeric Materials for Corrosion Control ACS Symposium Series; American Chemical Society: Washington, DC, 1986.