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Concluding Remarks F. E. BAILEY, JR. Union Carbide Corporation, Chemicals and Plastics, South Charleston, WV 25303
First, I want to thank those who participated in and those who helped to organize this very fine symposium. When I first became involved in the organization of the Macromolecular Secretariat in 1975, I suggested to Otto Vogl, then Secretary General, that a very suitable topic for a symposium would involve materials science aspects of macromolecular systems for the highly interdisciplinary character of the symposia sponsored by the Secretariat. Such a topic would touch not only on the most fundamental structure-property relationships, but also use of such relationships in real systems. Professor Vogl saw such a symposium topic as a means of involving research beyond the usual perimeters of an American Chemical Society meeting even of national scope and discussed the question further at our National Bureau of Standards, particularly with Dr. R. K. Eby. Dr. Eby graciously accepted the task of organizing the general program for this symposium, obtaining the participation of five Divisions of the American Chemical Society, each of which accepted responsibility for one of the sessions: the Polymer Chemistry Division, Rubber Division, Organic Coatings and Plastics Chemistry Division, the Colloid and Surface Chemistry Division and the Cellulose, Paper and Textile Division. We have also been joined in the Symposium by the High Polymer Physics Division of the American Physical Society and the Division of Engineering Structures and Properties of the Society of Plastics Engineers as well as two exceptional keynote speakers: Dr. John D. Hoffman of the National Bureau of Standards and Dr. Field Winslow of Bell Telephone Laboratories. As p l a s t i c s m a t e r i a l s a r e e v e r more w i d e l y u s e d , t h e n e c e s s i t y o f k n o w i n g t h e u s e - l i f e r e l a t i o n s h i p s has grown i n importance. Most commonly, t h e s e r e l a t i o n s h i p s a r e t h o u g h t o f i n terms o f s e r v i c e f o r l o n g p e r i o d s o f time. Rapid expansion o f u s e a n d n e e d f o r u s e h a s r e q u i r e d t h e d e v e l o p m e n t o f means o f predictative testing of materials durability. I r e c a l l the i m p a t i e n c e o f one o f o u r J f e i r k e t i n g p e r s o n n e l some y e a r s ago when a house we h a d p a i n t e d h a d w i t h s t o o d f i v e y e a r s o f New J e r s e y w e a t h e r a n d h e was d e v e l o p i n g s a l e s l i t e r a t u r e t o e m p h a s i z e t h e 0-8412-0485-3/79/47-095-467$05.00/0 © 1979 A m e r i c a n C h e m i c a l Society
Eby; Durability of Macromolecular Materials ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
DURABILITY O F MACROMOLECULAR MATERIALS
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t h e endurance o f t h i s p a r t i c u l a r v i n y l c o a t i n g : "Do I h a v e t o w a i t a n o t h e r 20 y e a r s t o w r i t e t h i s b r o c h u r e ? " The w o r k d i s c u s s e d h e r e has r e l a t e d n o t o n l y t o s t r u c t u r e r e l a t i o n s h i p s b u t a l s o t o means o f p r o t e c t i o n o f t h e m a c r o m o l e c u l a r m a t e r i a l and t h e p r o t e c t i v e f u n c t i o n s o f these m a t e r i a l s . T h e r e a r e many modes o f f a i l u r e , b y c h e m i c a l r e a c t i o n , f a i l u r e by f r a c t u r e , e n v i r o n m e n t a l s t r e s s c r a c k i n g a n d c r e e p . F u r t h e r t h e r e a r e c o m p l i c a t i n g i n t e r a c t i o n s a r i s i n g from chemical r e a c t i o n d u r i n g r e l a x a t i o n o f polymer networks, and i n multiphase polymer systems and c o m p o s i t e s , f a i l u r e a t i n t e r f a c e s by a d h e s i v e f a i l u r e or stress-stress d i l a t i o n . Modes o f a c c e l e r a t e d t e s t i n g h a v e l e d t o t h e d e v e l o p m e n t o f e x p r e s s i o n l i f e t i m e l i m i t s i n terms o f f a i l u r e envelopes w i t h i n w h i c h c o n f i d e n c e l e v e l s o f u s e c a n be g i v e n . I n a d d i t i o n t o modes o f t e s t i n g q u i t e l o n g i n use such as t e s t i n g o f wear, a b r a s i o n and e x p o s u r e , d a t a c a n now be e x p r e s s e d i n t e r m s o f m o l e c u l a r r e l a x a t i o n p r o c e s s e s a n d k i n e t i c s o f f a i l u r e a n d t i m e dependence of strength, i . e . , fatigue testing. Means h a v e b e e n d e v e l o p e d t o m e a s u r e v e r y l o w r e a c t i o n r a t e s o f t h e o r d e r o f 10~12 m o l / y e a r as w e l l as t h e s u b t l e e f f e c t s o f c h a n g e s i n m o l e c u l a r w e i g h t d i s t r i b u t i o n a n d " s t r e s s memory" e s p e c i a l l y i n r e i n f o r c e d p o l y m e r systems. I n t e r e s t i n p r e d i c a t i v e t e s t i n g extends not only t o l o n g p e r i o d s o f s e r v i c e but t o r e l a t i v e l y s h o r t time p e r i o d s as w e l l when b i o d e g r a d a b i l i t y i s c o n c e r n e d o r i n b i o c o m p a t i b l e s y s t e m s i n m e d i c a l u s e w h e t h e r i t b e i n a d h e s i o n o f bone o r p r o s t h e s i s o r p a c k a g i n g i s c o n c e r n e d , a n d i n f o o d a d d i t i v e s when f o r example a s p e c i e s may be o f c o n s e q u e n c e when p r e s e n t i n t h e p o l y m e r and p o t e n t i a l l y e x t r a c t e d o r p r e s e n t as a d e l i c a t e f l a v o r o r c o l o r and a b s o r b e d b y t h e m a c r o m o l e c u l a r s y s t e m . I n summary, t h i s h a s b e e n a most w o r t h w h i l e symposium f r o m both t h e t o p i c a l and i n t e r d i s c i p l i n a r y views. I want t o a g a i n thank t h e o r g a n i z e r s , t h e p a r t i c i p a n t s and e s p e c i a l l y o u r s i s t e r S o c i e t i e s i n m a k i n g t h i s Symposium a s u c c e s s . RECEIVED D e c e m b e r 8,
1978.
Eby; Durability of Macromolecular Materials ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
