Status Review of PMR Polyimides - ACS Symposium Series (ACS

2 Status Review of PMR Polyimides TITO T. SERAFINI

Downloaded by CORNELL UNIV on September 27, 2016 | http://pubs.acs.org Publication Date: August 28, 1980 | doi: 10.1021/bk-1980-0132.ch002

National Aeronautics and Space Administration, Lewis Research Center, Cleveland, OH 44135

Until r e c e n t l y the a p p l i c a t i o n o f polymer m a t r i x composite m a t e r i a l s has been limited t o s t r u c t u r a l components having use-temperature requirements which could be met by epoxy resins. Although h i g h temperature r e s i s t a n t polymer m a t r i x composites p r o v i d e d an o p p o r t u n i t y t o design s t r u c t u r e s having n e a r l y a t w o - f o l d increase in use-temperature, the chemistry and severe p r o c e s s i n g requirements o f e a r l y technology (condensation-type) h i g h temperat u r e polymers made it i m p r a c t i c a l and difficult to fabricate high quality s t r u c t u r a l components. I n c o n t r a s t , f i b e r r e i n f o r c e d epoxy r e s i n s can easily be processed u s i n g a variety o f techniques at relatively low temperatures and p r e s s u r e s . Studies conducted at the NASA Lewis Research Center led t o the development o f a c l a s s o f p o l y i m i d e s known as PMR ( f o r in situ p o l y m e r i z a t i o n o f monomer r e a c t a n t s) p o l y i m i d e s (1,2,3,4). I n the PMR approach, the r e i n f o r c i n g f i b e r s are impregnated w i t h a solution c o n t a i n i n g a mixture o f monomers d i s s o l v e d in a low boiling p o i n t alkyl a l c o h o l s o l v e n t . The monomers are essentially unr e a c t i v e at room temperature, but react in situ at e l e v a t e d temperatures t o form a t h e r m o - o x i d a t i v e l y s t a b l e p o l y i m i d e m a t r i x . These h i g h l y p r o c è s s a b l e a d d i t i o n - t y p e p o l y i m i d e s can be p r o cessed by e i t h e r compression (5.) or autoclave (6) molding t e c h niques and are now making i t p o s s i b l e t o r e a l i z e much o f the p o t e n t i a l o f h i g h temperature polymer m a t r i x composites. Our research has i d e n t i f i e d monomer r e a c t a n t combinations f o r two PMR p o l y i m i d e s d i f f e r i n g i n chemical composition. The e a r l i est or " f i r s t generation" PMR m a t e r i a l i s designated PMR-15 and a more r e c e n t l y developed "second generation" m a t e r i a l i s designated PMR I I (j). Prepreg m a t e r i a l s employing PMR-15 are commercially a v a i l a b l e from the major s u p p l i e r s o f prepreg m a t e r i a l s . The development o f a m o d i f i e d PMR-15 has been r e p o r t e d (8). The purpose o f t h i s paper i s t o review the current s t a t u s o f f i r s t and second generation PMR p o l y i m i d e s . The f o l l o w i n g t o p i c s are reviewed: ( l ) synthesis and p r o p e r t i e s , (2) p r o c e s s i n g , and (3) a p p l i c a t i o n s .

This chapter not subject to U.S. copyright. Published 1980 American Chemical Society May; Resins for Aerospace ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

RESINS

16

FOR AEROSPACE

Discussion Synthesis and P r o p e r t i e s . Condensation type a r y l p o l y i m i d e s a r e g e n e r a l l y s y n t h e s i z e d "by r e a c t i n g a r y l d i a m i n e s w i t h a r o m a t i c dianhydrides aromatic t e t r a c a r b o x y l i c acids o r d i a l k y l esters o f a r o m a t i c t e t r a c a r b o x y l i c a c i d s . The d i a m i n e / d i a n h y d r i d e r e a c t i o n i s p r e f e r r e d f o r p r e p a r i n g p o l y i m i d e f i l m s w h e r e a s t h e l a t t e r two reactions are generally preferred f o r preparing polyimide matrix resins. The s o l u t i o n u s e d t o i m p r e g n a t e f i b e r r e i n f o r c e m e n t m a t e r i a l s i s prepared by d i s s o l v i n g t h e reactants i n a p r o t i c h i g h b o i l i n g p o i n t s o l v e n t s s u c h a s Ν,N-dimethylformamide (DMF) o r N - m e t h y l 2 - p y r r o l i d o n e (NMP). D u r i n g c o m p o s i t e s f a b r i c a t i o n , v o l a t i l i z a t i o n o f t h e solvent and condensation r e a c t i o n by-products r e s u l t s i n h i g h v o i d content composites having i n f e r i o r mechanical p r o p e r t i e s and t h e r m o - o x i d a t i v e s t a b i l i t y . I n v e s t i g a t o r s a t t h e S y s t e m s Group o f TRW, I n c . , w o r k i n g u n d e r NASA s p o n s o r s h i p , d e v e l o p e d a n a p p r o a c h t o p r e p a r e p o l y i m i d e s b y means o f a n a d d i t i o n r e a c t i o n (j?). T h e i r a p p r o a c h c o n s i s t e d o f s y n t h e s i z i n g low molecular weight amide-acid prepolymers whose c h a i n ends w e r e t e r m i n a t e d , o r e n d - c a p p e d , w i t h n o r b o r n e n y l groups. A d d i t i o n p o l y m e r i z a t i o n o f t h e n o r b o r n e n y l groups o c c u r r e d a t e l e v a t e d t e m p e r a t u r e s (275°-350° C)(527°-662° F ) w i t h o u t the e v o l u t i o n o f v o l a t i l e m a t e r i a l s making i t p o s s i b l e t o synthe s i z e l o w v o i d c o m p o s i t e s . The p r e p o l y m e r a p p r o a c h , h o w e v e r , d i d h a r e s e v e r a l s h o r t c o m i n g s . These i n c l u d e d : ( l ) t h e u s e o f DMF, (2) v a r i a b l e s o l u t i o n s t a b i l i t y , a n d (3) l e s s t h a n d e s i r a b l e t h e r m o - o x i d a t i v e s t a b i l i t y a t 316° C (600° F ) . A n o t h e r a p p r o a c h was d e v e l o p e d i n o u r l a b o r a t o r i e s f o r p r e p a r i n g f i b e r r e i n f o r c e d a d d i t i o n - t y p e p o l y i m i d e s . Our a p p r o a c h e l i m i n a t e d t h e n e e d f o r p r e p o l y m e r s y n t h e s i s a n d c i r c u m v e n t e d most of t h e shortcomings a s s o c i a t e d w i t h t h e use o f prepolymers. I n our approach a d i a l k y l e s t e r o f an aromatic t e t r a c a r b o x y l i c a c i d , an a r o m a t i c d i a m i n e a n d a m o n o a l k y 1 e s t e r o f 5 ~ n o r b o r n e n e - 2 , 3 d i c a r b o x y l i c a c i d (NE), a r e d i s s o l v e d i n a low b o i l i n g p o i n t a l k y l a l c o h o l , such as methanol o r e t h a n o l , and t h e s o l u t i o n i s used t o impregnate t h e r e i n f o r c i n g f i b e r s . T h e number o f m o l e s o f e a c h monomer r e a c t a n t i s g o v e r n e d b y t h e f o l l o w i n g r a t i o :


?

n:

(n + l ) :

2

Where n , ( n + l ) a n d 2 a r e t h e number o f m o l e s o f t h e d i a l k y l e s t e r o f t h e aromatic t e t r a c a r b o x y l i c a c i d , t h earomatic diamine and NE, r e s p e c t i v e l y . I n s i t u p o l y m e r i z a t i o n o f t h e monomer r e a c t a n t s (PMR) o c c u r s upon h e a t i n g t h e i m p r e g n a t e d f i b e r s . I n t h e i n i t i a l s t u d y (l) w h i c h e s t a b l i s h e d t h e f e a s b i l i t y o f t h e PMR a p p r o a c h , i t was n o t e d t h a t c o m p o s i t e s made f r o m monomer solutions containing the dimethyl ester o f 3,3 b e n z o p h e n o n e t e t r a c a r b o x y l i c a c i d (BTDE), k,h -methylenedianiline (MDA) a n d NE e x h i b i t e d a h i g h e r l e v e l o f t h e r m o - o x i d a t i v e s t a b i l i t y t h a n d i d c o m p o s i t e s p r e p a r e d f r o m a monomer s o l u t i o n c o n s i s t !

f

May; Resins for Aerospace ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

2.

sERAFiNi

PMR

17

Polyimides


i n g o f t h e d i m e t h y l e s t e r o f p y r o m e l l i t i c a c i d , MDA a n d NE. The u n e x p e c t e d o b s e r v a t i o n was c o n f i r m e d i n a s u b s e q u e n t s t u d y ( l p ) and t h e optimum number o f m o l e s o f BTDE (n) w h i c h p r o v i d e d t h e best o v e r a l l balance o f p r o c e s s i n g c h a r a c t e r i s t i c s and thermoo x i d a t i v e s t a b i l i t y was f o u n d t o b e 2.087, c o r r e s p o n d i n g t o a PMR p o l y i m i d e h a v i n g a f o r m u l a t e d m o l e c u l a r w e i g h t (FMW) o f 1500. The FMW i s c o n s i d e r e d t o b e t h e a v e r a g e m o l e c u l a r w e i g h t o f i m i d i z e d p r e p o l y m e r t h a t c o u l d have b e e n f o r m e d i f a m i d e - a c i d p r e p o l y m e r had b e e n s y n t h e s i z e d . The e q u a t i o n f o r t h e FMW o f a PMR p o l y i m i d e p r e p a r e d f r o m η m o l e s o f BTDE ( n + l ) m o l e s o f MDA a n d 2 m o l e s of NE i s ;

™ *

=

N

^BTDE

+

(

N

+

1

)

M

W

MDA

+

2

W

m

~

2

(

n

+

1

]

Μ

ϋ

2

0

+

M W C

H 0H 3

Where MWgip-p-g, MWJ^Q^, e t c . , a r e t h e m o l e c u l a r w e i g h t s o f t h e monoer reactants and by-products. I t i s now common p r a c t i c e t o d e n o t e t h e s t o i c h i o m e t r y o f a PMR r e s i n b y d i v i d i n g t h e FMW b y 100. PMR m a t r i c e s e m p l o y i n g BTDE a r e r e f e r r e d t o a s " f i r s t g e n e r a t i o n " materials. The f i r s t g e n e r a t i o n PMR m a t r i x p r e p a r e d f r o m BTDE, MDA a n d NE h a v i n g a n FMW o f 1500 i s w i d e l y known a s PMR-15. Pre p r e g m a t e r i a l s b a s e d o n PMR-15 a r e c o m m e r c i a l l y a v a i l a b l e f r o m t h e m a j o r p r e p r e g s u p p l i e r s . The s t r u c t u r e s o f t h e monomers u s e d i n PMR-15 a r e shown i n T a b l e I . These e a r l y s t u d i e s ( 1 , 1 0 ) a l s o c l e a r l y d e m o n s t r a t e d t h e e f f i c a c y a n d v e r s a t i l i t y o f t h e PMR a p p r o a c h . B y v a r y i n g t h e chemical nature o f e i t h e r the d i a l k y l e s t e r a c i d o r aromatic d i a m i n e , o r b o t h , a n d t h e monomer r e a c t a n t s t o i c h i o m e t r y , PMR m a t r i ces h a v i n g a b r o a d range o f p r o c e s s i n g c h a r a c t e r i s t i c s and p r o p e r t i e s c o u l d e a s i l y be s y n t h e s i z e d . A m o d i f i e d PMR-15, c a l l e d LARC160, h a s been d e v e l o p e d b y s u b s t i t u t i n g a n a r o m a t i c p o l y a m i n e f o r MDA (8). O t h e r s t u d i e s ( 11,12 ) have shown t h a t t h e PMR a p p r o a c h has e x c e l l e n t p o t e n t i a l f o r " t a i l o r m a k i n g " m a t r i x r e s i n s w i t h s p e c i f i c p r o p e r t i e s . F i g u r e 1 shows t h e e f f e c t o f FMW o n r e s i n f l o w f o r PMR/HTS g r a p h i t e f i b e r c o m p o s i t e s . I t c a n b e s e e n t h a t s i g n i f i c a n t l y h i g h e r r e s i n f l o w can b e a c h i e v e d b y r e d u c i n g t h e FMW. However, a s shown i n F i g u r e 2, t h e PMR c o m p o s i t i o n s w h i c h e x h i b i t increased r e s i n flow are l e s s thermo-oxidatively s t a b l e a t 288° C (550° F ) . The l o w e r r e s i n f l o w a n d i n c r e a s e d t h e r m o o x i d a t i v e s t a b i l i t y i n g o i n g f r o m PMR-10 t o PMR-15 c l e a r l y show the s e n s i t i v i t y o f these p r o p e r t i e s t o imide r i n g o r a l i c y c l i c contents. The r e d u c t i o n i n r e s i n f l o w w i t h i n c r e a s e d FMW a l s o s e r v e s t o quant i t a t i v e l y account f o r t h e i n t r a c t a b l e n a t u r e o f l i n e a r high molecular weight condensation polyimides. R e p l a c e m e n t o f B T D E w i t h t h e d i m e t h y l e s t e r o f k k'(hexafluoroisopropylidene)-bis ( p h t h a l i c acid) (HFDE) s i g n i f i c a n t l y improved the thermo-oxidative s t a b i l i t y o f " f i r s t g e n e r a t i o n " PMR r e s i n s (12). However, t h e i n i t i a l 3l6° C (600° F ) m e c h a n i c a l p r o p e r t i e s o f HFDE/MDA/NE PMR p o l y i m i d e c o m p o s i t e s w e r e c o n s i d e r a b l y l o w e r t h a n t h e c o r r e s p o n d i n g p r o p e r t i e s o f B T D E / M D A / N E PMR polyimides. G r a p h i t e f i b e r r e i n f o r c e d PMR p o l y i m i d e c o m p o s i t e s 9


18

RESINS

FOR

AEROSPACE

TABLE I MONOMERS

U S E D FOR

STRUCTURE

PMR 15

POLYIMIDE ABBREVIATION

NAME

ο

p h e n y l e n e d i a m i n e a n d NE a t a n FMW o f 1267 ( n = 1.67) w e r e f o u n d t o e x h i b i t s i g n i f i c a n t l y improved t h e r m o - o x i d a t i v e s t a b i l i t y and r e t e n t i o n o f m e c h a n i c a l p r o p e r t i e s a t 3l6° C (600° F ) compared t o PMR-15 c o m p o s i t e s ( j ) . The HFDE-PMR c o m p o s i t i o n s a r e r e f e r r e d t o as " s e c o n d g e n e r a t i o n " m a t e r i a l s t o d i f f e r e n t i a t e t h e m f r o m t h e " f i r s t g e n e r a t i o n " BTDE-PMR m a t e r i a l s . The " s e c o n d g e n e r a t i o n " r e s i n c o n s i s t i n g o f HFDE, PPDA a n d NE w i t h η = 1.67, i s known a s PMR I I . The s t r u c t u r e o f t h e monomers u s e d i n PMR I I a r e shown i n T a b l e I I . The i n t e r l a m i n a r s h e a r s t r e n g t h o f PMR I I ( n = 1.67) and PMR-13 ( a f i r s t g e n e r a t i o n c o m p o s i t i o n w i t h η = 1.67) HTS g r a p h i t e f i b e r c o m p o s i t e s a r e compared i n F i g u r e 3. I t c a n b e s e e n t h a t t h e PMR I I c o m p o s i t e s have a t l e a s t t w i c e t h e u s e f u l 316° C (600° F ) l i f e o f t h e e a r l i e r PMR c o m p o s i t e s . PMR I I was compared t o PMR-13 b e c a u s e t h e y e a c h c o n t a i n a n i d e n t i c a l number of imide r i n g s . F u r t h e r improvement i n t h e p e r f o r m a n c e o f PMR p o l y i m i d e s a t e l e v a t e d t e m p e r a t u r e s h a s b e e n made p o s s i b l e b y t h e r e c e n t d e v e l opment o f g r a p h i t e f i b e r s w i t h i m p r o v e d t h e r m o - o x i d a t i v e s t a b i l i t y . F i g u r e k compares t h e w e i g h t l o s s c h a r a c t e r i s t i c s o f PMR-15 com p o s i t e s made w i t h H T S - 1 , H T S - 2 , a n d C e l i o n 6000 g r a p h i t e f i b e r s a f t e r i s o t h e r m a l e x p o s u r e i n a i r a t 3l6° C (600° F ) . The HTS-1 c o m p o s i t e d a t a a r e f r o m R e f e r e n c e 10 a n d t h e HTS-2 a n d C e l i o n 6000 c o m p o s i t e a r e f r o m R e f e r e n c e 1 3 . The d a t a p r e s e n t e d i n t h e f i g u r e c l e a r l y show t h e s i g n i f i c a n t l y i m p r o v e d e l e v a t e d t e m p e r a t u r e s t a b i l i t y o f t h e HTS-2 a n d C e l i o n 6000 c o m p o s i t e s compared t o t h e HTS-1 c o m p o s i t e s . F i g u r e 5 compares t h e i n t e r l a m i n a r s h e a r s t r e n g t h r e t e n t i o n a f t e r e x p o s u r e i n a i r a t 3l6° C (600° F ) o f PMR-15/HTS-1, PMR-15/ HTS-2 a n d P M R - 1 5 / C e l i o n 6000 c o m p o s i t e s . I t c a n b e s e e n t h a t b o t h t h e HTS-2 a n d C e l i o n 6000 c o m p o s i t e s e x h i b i t e d 100 p e r c e n t r e t e n t i o n o f t h e i r i n i t i a l 316° C (600° F ) i n t e r l a m i n a r s h e a r s t r e n g t h d u r i n g t h e f i r s t 1000 h o u r s o f e x p o s u r e . The s h e a r s t r e n g t h t h e n s l o w l y d e c r e a s e d w i t h f u r t h e r e x p o s u r e . These m e c h a n i c a l p r o p e r t y d a t a a n d t h e c o m p o s i t e w e i g h t l o s s d a t a shown i n t h e p r e v i o u s f i g u r e c l e a r l y show t h a t t h e u s e f u l l i f e o f PMR-15 c o m p o s i t e s a t 316° C (600° F ) made w i t h h i g h s t r e n g t h , i n t e r m e d i a t e modulus g r a p h i t e f i b e r s s u c h a s HTS-2 a n d C e l i o n 6000 i s a t l e a s t 1000 hours. Composites P r o c e s s i n g . High p r e s s u r e (compression) and l o w p r e s s u r e ( a u t o c l a v e ) m o l d i n g c y c l e s have been developed f o r f a b r i c a t i o n o f PMR c o m p o s i t e s . A l t h o u g h t h e t h e r m a l l y i n d u c e d c r o s s l i n k i n g a d d i t i o n cure r e a c t i o n o f t h e n o r b o r n e n y l group o c c u r s a t t e m p e r a t u r e s i n t h e r a n g e o f 275° t o 350° C (527° t o 662° F ) , n e a r l y a l l o f t h e p r o c e s s e s d e v e l o p e d u s e a maximum c u r e t e m p e r a t u r e o f 316° C (600° F ) . C u r e t i m e s o f 1 t o 2 h o u r s f o l l o w e d b y a f r e e s t a n d i n g p o s t - c u r e i n a i r a t 3l6° C (600° F ) f o r k t o l 6 h o u r s , a r e a l s o n o r m a l l y employed. Compression m o l d i n g c y c l e s g e n e r a l l y employ h i g h r a t e s o f h e a t i n g (5° t o 10° C/min) a n d près-


20

RESINS

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AEROSPACE

TABLE I I MONOMERS

USED

FOR

SECOND

GENERATION

PMR

POLYIMIDES ABBREVIATION

NAME

STRUCTURE 0 C-OMe

MONOMETHYL ESTER OF 5-N0RB0RNENE-2, 3-DICARBOXYLIC ACID

NE

DIMETHYL ESTER OF 4, 4 ' (HEXAFLUOROISOPROPYLIDENE) BIS(PHTHALIC ACID)

HFDE

£-PHENYLENEDIAMINE

PPDA

n

0

0

0


MeO-C

ÇF3

HO-C

3

t

C-OH

0

0

H2N-^-NH

C-OMe

2

lfolO3

1000

400 600 TIME, HR

Figure 3. Interlaminar shear strength of PMR PI(n = 1.67)/HTS graphite fiber composites exposed and tested at 316°C (600°F): (A) BTME/MDA/NE, (O) HFDE/PPDA/NE, solid symbols denote room-temperature tests

55X10

3

11 800

Figure 4.

1200 TIME, h r

1600

2400

Weight loss of PMR 15/'graphite fiber composites exposed in air at 316°C (600°F); fiber: (·) HTS-1, (O) HTS-2, (A) Celion 6000


2.

sERAFiNi

PMR

21

Polyimides

s u r e s i n t h e r a n g e o f 3.^5x10^ t o 6.9x10^ N/m (500 t o 1000 p s i ) . Vacuum h a g a u t o c l a v e p r o c e s s e s a t l o w h e a t i n g r a t e s (2° t o k° C/ min) a n d p r e s s u r e s o f 1.38x10^ N/m (200 p s i ) o r l e s s h a v e "been s u c c e s s f u l l y u s e d t o f a b r i c a t e v o i d - f r e e c o m p o s i t e s . The s u c c e s s f u l a p p l i c a t i o n o f a u t o c l a v e p r o c e s s i n g m e t h o d o l o g y t o PMR p o l y imides r e s u l t s from the presence o f a t h e r m a l t r a n s i t i o n , termed " m e l t - f l o w , " which occurs over a f a i r l y broad temperature range (6). The l o w e r l i m i t o f t h e m e l t - f l o w t e m p e r a t u r e r a n g e depends on a number o f f a c t o r s i n c l u d i n g t h e c h e m i c a l n a t u r e and s t o i c h i o m e t r y o f t h e monomer r e a c t a n t m i x t u r e , and t h e p r i o r t h e r m a l h i s t o r y o f t h e PMR p r e p r e g . D i f f e r e n t i a l s c a n n i n g c a l o r i m e t r y s t u d i e s h a v e shown t h e p r e s e n c e o f f o u r t h e r m a l t r a n s i t i o n s w h i c h o c c u r d u r i n g t h e o v e r a l l c u r e o f a PMR p o l y i m i d e (ik). The f i r s t , s e c o n d and t h i r d t r a n s i t i o n s a r e e n d o t h e r m i c and a r e r e l a t e d t o the f o l l o w i n g : ( l ) m e l t i n g o f t h e monomer r e a c t a n t m i x t u r e b e l o w 100° C (212° F ) , ( 2 ) i n s i t u r e a c t i o n o f t h e monomers a t l*+0° C (28^° F ) , and ( 3 ) m e l t i n g o f t h e n o r b o r n e n y l t e r m i n a t e d p r e p o l y •mers i n t h e r a n g e o f 175° t o 250° C (3*+7° t o 1+82° F ) r e f e r r e d t o as t h e m e l t - f l o w t e m p e r a t u r e r a n g e . The f o u r t h t r a n s i t i o n , c e n t e r e d n e a r 3^0° C (6kh° F ) i s e x o t h e r m i c and i s r e l a t e d t o t h e addition crosslinking reaction. To a l a r g e e x t e n t t h e e x c e l l e n t p r o c e s s i n g c h a r a c t e r i s t i c s o f PMR p o l y i m i d e s c a n be a t t r i b u t e d t o t h e p r e s e n c e o f t h e s e w i d e l y s e p a r a t e d and c h e m i c a l l y d i s t i n c t thermal t r a n s i t i o n s . 2


2

Applications. Because o f t h e i r e x c e l l e n t p r o c e s s i n g c h a r a c t e r i s t i c s and c o m m e r c i a l a v a i l a b i l i t y , PMR-15 p o l y i m i d e m a t e r i a l s have b e e n o r a r e b e i n g u s e d i n a number o f d i v e r s e s t r u c t u r a l components. Some o f t h e s e components a r e l i s t e d i n T a b l e I I I and a b r i e f d e s c r i p t i o n o f s e v e r a l i s p r e s e n t e d . The QCSEE ( f o r Q u i e t C l e a n S h o r t H a u l E x p e r i m e n t a l E n g i n e ) i n n e r c o w l ( F i g . 6) i s f o r an e x p e r i m e n t a l t u r b o f a n e n g i n e d e v e l o p e d f o r NASA-Lewis b y Gene r a l E l e c t r i c ( 1 5 ) . The c o w l has a maximum d i a m e t e r o f a b o u t 90 cm and has s u c c e s s f u l l y u n d e r g o n e more t h a n 100 h o u r s o f g r o u n d engine t e s t s . The c o m p r e s s o r b l a d e s k i n s a r e f o r s p a r s h e l l b l a d e s h a v i n g a 30 cm c h o r d a n d a 150 cm s p a n . The o i l t a n k b r a c k e t was f a b r i c a t e d b y TRW, I n c . , u s i n g a chopped g r a p h i t e f i b e r m o l d i n g compound. The s h u t t l e o r b i t e r a f t body f l a p c u r r e n t l y b e i n g d e v e l o p e d b y B o e i n g i s a p p r o x i m a t e l y 2 m w i d e b y 6.5 m l o n g . C o n c l u d i n g Remarks The i n s i t u p o l y m e r i z a t i o n o f monomer r e a c t a n t s (PMR) a p p r o a c h i s a p o w e r f u l method f o r f a b r i c a t i n g h i g h p e r f o r m a n c e p o l y mer m a t r i x c o m p o s i t e s . The PMR a p p r o a c h o f f e r s a number o f s i g n i f i c a n t a d v a n t a g e s t o f a b r i c a t o r s and u s e r s o f p o l y i m i d e / f i b e r c o m p o s i t e s . F o r e m o s t among t h e s e a r e s u p e r i o r h i g h t e m p e r a t u r e p r o p e r t i e s and p r o c e s s i n g v e r s a t i l i t y . Because o f t h e i r e x c e l l e n t p r o c e s s a b i l i t y , h i g h p e r f o r m a n c e a n d c o m m e r c i a l a v a i l a b i l i t y , PMR


22

RESINS F O R


Figure 5. Interhminar shear strength of PMR 15/graphite fiber composites exposed and tested in air at 316°C (600°F); fiber: (·) HTS-1, (O) HTS-2, (A) Celion 6000

TABLE IE A P P L I C A T I O N S OF P M R - 1 5

POLYIMIDES

AGENCY

COMPONENT

CONTRACTOR

QCSEE INNER COWL

NASA-LEWIS

GENERAL ELECTRIC

SUPERSONIC WIND TUNNEL

AIR-FORCE

HAMILTON-STANDARD

NAVY

PRATT & WHITNEY/TRW

COMPRESSOR BLADE SKINS OIL TANK BRACKET FOR F100 ENGINE SHUTTLE ORIBTER AFT BODY FLAP

NASA-LANGLEY

BOEING

AUGMENTOR DUCT OF F100 ENGINE

AIR FORCE

COMPOSITES HORIZONS

FAN BLADES FOR AN ULTRA-HIGH

NASA-LEWIS

PRATT & WHITNEY/TRW

SPEED AXIAL FLOW FAN STAGE

Figure 6.

PMR 15 QCSEE

inner cowl


AEROSPACE

2.

SERAFiNi

PMR

23

Polyimides

p o l y i m i d e s a r e b e c o m i n g a c c e p t e d as e n g i n e e r i n g m a t e r i a l s f o r f a b r i c a t i o n o f h i g h t e m p e r a t u r e r e s i n / f i b e r s t r u c t u r a l components.


Literature Cited 1.

Serafini, T. T . ; D e l v i g s , P.; L i g h t s e y , G. R. J. A p p l . Polym. Sci., 1972, 16, 905.

2.

Serafini, T. T . ; D e l v i g s , U . S . P a t . 3,745,149.

3.

Serafini, T. T . ; D e l v i g s , P . 1973, J. A p p l . Polym. A p p l . Polym. Symp., No. 22, 89.

4.

Serafini, T. T. "Proc. o f the 1975 I n t e r n a t i o n a l Conference on Composite Materials," Scala, Ε . , Ed.; American Institute o f M i n i n g , M e t a l l u r g i c a l and Petroleum Engineers: New York, 1976; V o l . 1, p . 202.

5. Cavano, P.

J.;

P.;

L i g h t s e y , G. R. J u l y 10,

1973,

Sci.,

W i n t e r s , W. E . 1976, NASA CR-135113.

6. Vannucci, R. D. 1977, NASA TM-73701. 7.

Serafini, TM-71894.

T. T . ; Vannucci, R. D . ;

Alston,

W. B . 1976, NASA

8. S t . Clair, T. L.; Jewell, R. A . " P r o c . o f Twenty-Third N a t i o n a l SAMPE Symposium and Exhibition," S o c i e t y f o r the A d vancement o f M a t e r i a l and Process E n g i n e e r i n g : Azusa, Calif., 1978; p . 520. 9. Burns, E . A.; Lubowitz, H . R.; Jones, J. F . 1968 NASA CR-72460. 10. D e l v i g s , D-6877.

P.;

11.

T. T . ; Vannucci, R. D. 1975, NASA TM X-71616.

Serafini,

Serafini,

T. T . ; L i g h t s e y , G. R. 1972, NASA TN

12. Vannucci, R. D . ; A l s t o n , W. B. 1976, NASA TM X-71816. 13. D e l v i g s , P.; A l s t o n , W. B.; and Vannucci, R. D. 1979, NASA TM-79062. 14. Lauver, R. W. 1977, NASA TM-78844. 15. Ruggles, C. L . 1978, NASA CR-135279. RECEIVED April 8,

1980.


Status Review of PMR Polyimides - ACS Symposium Series (ACS

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