I/EC
R E P O R T S
A N D
I N T E R P R E T S
SILICONES
Here's why your competitors may use General Electric silicone fluids! Adding small amounts of C-E sili cone fluids can greatly improve the characteristics of many products. For instance: A small amount added to polishes increases sheen, durability and ease of application. Helps give a finish that resists stains and repels water. A small amount added during the manufacture of polyurethane foam controls cell size and uniformity. ι
A small amount added to paints
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improves gloss retention, stain and mar resistance. Application is easier; flotation, silking, orange peel are eliminated.
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A small amount added to lotions and cosmetics helps protect the skin against water-borne irritants. A small amount added to resins and plastics improves surface lubricity and appearance. General Electric silicone additives make pigments hydrophobic and freeflowing, improve wetting by organic vehicles. They are also excellent antifoam agents in aqueous and non aqueous systems. Colorless, odorless, tasteless, they are easy to work with.
To learn more about this tive, and how it may help products, write: General pany, Silicone Products Section TT855, Walerford,
GENERAL
versatile addi improve your Electric Com Department, New York.
ELECTRIC
A Va-inch thick rubber sheet withstands 5 0 0 0 ° F. flame oxyacetylene torch while an identical flame burns through the ' / H n c h steel slab in the rear
flow of air t h r o u g h t h e t u n n e l r e m a i n e d c o n s t a n t a t 0.0011 p o u n d p e r s e c o n d ; heat-flux d e n s i t y v a r i e d slightly for t h e v a r i o u s s a m p l e s b u t a v e r a g e d a b o u t 4 0 B.t.u. p e r s q u a r e foot p e r s e c o n d ; m a x i m u m surface temperature ran about 3000° F. I n these tests, G E ' s R T V - 8 8 form u l a t i o n a b l a t e s o n l y 1 5 % as fast as t h e phenolic—nylon m a t e r i a l ; S E 555 (a w h i t e o v e n - c u r e d r u b b e r ) a b l a t e s e v e n m o r e slowly. U n d e r test c o n d i t i o n s of the p l a s m a t u n n e l , t h e silicone r u b b e r s all b e h a v e similarly. After r u n s of 5 to 10 m i n u t e s , a h a r d c a r b o n a c e o u s crust covers a second layer w h i c h is n o t q u i t e so h a r d a n d w h i c h forms a n o p e n - c e l l s t r u c t u r e . B e n e a t h this s e c o n d c h a r r e d l a y e r lies a t h i n decomposing layer of sponged silicone r u b b e r . T h e s e t h r e e layers together comprise not more than 3 0 % of t h e total s a m p l e thickness.
Circle No. 17 on Readers' Service Card
30 A
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Ablating and Insulating T h e i n s u l a t i n g p r o p e r t i e s of t h e silicones a r e p a r t i c u l a r l y n o t e w o r t h y . T h i r t y seconds e x p o s u r e to t h e 9 0 0 0 ° F . p l a s m a raises t h e i n t e r n a l t e m p e r a t u r e of the R T V - 6 0 s p e c i m e n to o n l y 1 0 0 ° F . After 6 m i n u t e s , t e m p e r a t u r e 0.16 inch b e l o w t h e surface r e a c h e s 7 7 0 ° F . ; a t t h e 0.33-inch level it is o n l y 4 7 5 ° F . A c h e m i c a l flame ( o x y g e n - a c e t y l e n e t o r c h p r o d u c i n g 5 5 0 0 ° F.) gives t h e s a m e t y p e of c h a r layers. A n d a n a i r - a r c i m a g e f u r n a c e ( w i t h ellip soidal m i r r o r s to c o n c e n t r a t e t h e h e a t ) , boosting surface t e m p e r a t u r e to 3 4 0 0 ° F . for a m i n u t e , a b l a t e s t h e R T V - 8 8 o n l y half as fast as t h e plasma jet does. T o G E , these results m e a n t h a t c e r t a i n silicone r u b b e r c o a t i n g s c a n p r o t e c t all s t r u c t u r e s of t h e aft {Continued on page 32 A)
