Computer Applications in Applied Polymer Science - American

27

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 27, 2016 | http://pubs.acs.org Publication Date: September 24, 1982 | doi: 10.1021/bk-1982-0197.ch027

Design and Analysis of an Acrylonitrile-ButadieneStyrene (ABS) Pipe Compound Experiment M. H. WILT and G. F. KOONS United States Steel Corporation, Research Center, Monroeville, PA 15146 Selected blends of styrene-acrylonitrile co polymer (30 to 55%), a styrene-butadiene copolymer grafted with styrene and acrylonitrile (45 to 70%), and a coal-tar pitch (0 to 25%), were prepared. Physical properties of the experimental blends were determined and statistical techniques were used to develop empirical equations relating these properties to blend composition. Scheffécanoni cal polynominal models and response surfaces pro vided a thorough understanding of the mixture system. These models were used to determine the amount of coal-tar pitch that could be incorpo rated into ABS compounds that would still meet ASTM requirements for various pipe-material desig nations. A s i g n i f i c a n t r e d u c t i o n i n c o s t c o u l d be a c h i e v e d i f a p p r e c i a b l e q u a n t i t i e s o f c o a l - t a r p i t c h c o u l d be i n c o r p o r a t e d i n t o ABS f o r t h e p r o d u c t i o n o f a s a t i s f a c t o r y p i p e compound. B e cause o f t h e a v a i l a b i l i t y o f t r a i n e d p l a s t i c s and mathematics p e r s o n n e l a t t h e U. S. S t e e l R e s e a r c h L a b o r a t o r y , a n i n t e r d i s c i p l i n a r y a p p r o a c h was made t o t h e p r o b l e m . B e f o r e a n y b l e n d i n g was d o n e , a n a p p r o p r i a t e e x p e r i m e n t was d e s i g n e d t o o b t a i n a maximum o u t p u t o f i n f o r m a t i o n w i t h a minimum amount o f experimentation. T h i s paper r e p o r t s t h e r e s u l t s and a n a l y s i s of t h e experimentation. M a t e r i a l s and E x p e r i m e n t a l For t h i s study

Work

t h e m a t e r i a l s shown i n T a b l e I w e r e u s e d .

0097-6156/ 82/0197-0439 $06.00/0 © 1982 American Chemical Society Provder; Computer Applications in Applied Polymer Science ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

COMPUTER APPLICATIONS IN APPLIED POLYMER SCIENCE

440

Table I Blend Components


Styrene-butadiene copolymer - 19 percent SAN; 81 percent g r a f t g r a f t e d with styrene and acrylonitrile Styrene-acrylonitrile copolymer (SAN)

- Mn 64,600, Mw 179,800; percent AN 27.5

Coal-tar p i t c h p r i l l s

- S.P. 112°C

Blends were produced i n a s m a l l Banbury mixer. About 3 l b o f dry-blended m a t e r i a l was added t o the Banbury. A f t e r the f l u x p o i n t , blends were run f o r two more minutes and dumped. C o n d i t i o n s were speed No. 2, 30 p s i on the ram, and a dump temp e r a t u r e o f 310°F. Test specimens were molded on a 3-oz Van Dorn i n j e c t i o n - m o l d i n g machine; f r o n t , middle, and r e a r zones were 500, 485, and 470°F, r e s p e c t i v e l y . The mold temperature was 160°F; the molding c y c l e was t y p i c a l f o r ABS. Test methods were ASTM Standard Procedures. Experimental

Design

The major c o n s i d e r a t i o n i n s e l e c t i n g the experimental r e gion f o r t h i s study was t h a t i t i n c l u d e compositions t h a t c o u l d be expected t o produce acceptable p i p e compounds. A second cons i d e r a t i o n was t h a t the r e g i o n be comprehensive enough t o i n clude blends c o n t a i n i n g p i t c h i n excess o f the maximum amount t h a t c o u l d be acceptably added t o p i p e compounds. In other words, i f the experiment was t o i n d i c a t e the maximum t o l e r a b l e amount o f p i t c h , then some blends c o n t a i n i n g unacceptable amounts a l s o had t o be s t u d i e d . The experimental r e g i o n , shown by the t e r n a r y diagram i n F i g u r e 1, contained blends ranging from 45 t o 70 percent g r a f t , 30 t o 55 percent SAN, and up t o 25 percent p i t c h . T h i s r e g i o n i s o n l y a p o r t i o n o f a l l the p o s s i b l e combinations o f the three components. A mathematical t r a n s f o r m a t i o n was made t o convert the abs o l u t e amounts o f each element t o t h e i r r e l a t i v e amounts w i t h i n the subregion s t u d i e d . These r e l a t i v e amounts are c a l l e d pseudocomponents (1) . F o r example, the blend c o n s i s t i n g o f 45 percent g r a f t , 30 percent SAN, and 25 percent p i t c h c o n t a i n s the maximum amount o f p i t c h and minimum amounts o f the other c o n s t i t u e n t s . I f x^, X^, and X^ represent the r e l a t i v e amounts o f each component, the p i t c h v e r t e x can be l a b e l e d X =0.0, X = 0.0, and X = 1.0 (Figure 2 ) . 1 2 * See References. Provder; Computer Applications in Applied Polymer Science ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

WILT AND KOONS

ABS

Pipe Compound

441

Experiment


25% PITCH

/45% GRAFT

30% SAN

'0% GRAFT

100% SAN

100% GRAFT

Figure 1. Schema showing experimental blends and resultant Izod values.

X = 1 3

c

X = 1 2

6.1 — • — —

7.3 —

7

.

4

X., = 1

Figure 2. Schema of experimental region. Blend indicated by letters and measured Izod indicated by numbers. X = (GRAFT-0.45)/0.25; X = (SAN-0.30)/0.25; X = t

2

s

PITCH/0.25

Provder; Computer Applications in Applied Polymer Science ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

442



Results and D i s c u s s i o n The Izod impact, d e f l e c t i o n temperature under l o a d (DTUL), and y i e l d s t r e n g t h (YS) o f each experimental blend were d e t e r mined. The r e s u l t s a r e presented i n Table I I . F i g u r e 2 a l s o shows the Izod impact r e s u l t s . There were obvious and a n t i c i p a t e d s y n e r g i s t i c e f f e c t s o p e r a t i v e w i t h i n the system. F o r example, c o n s i d e r the blends t h a t contained no p i t c h ; as g r a f t i n i t i a l l y r e p l a c e d SAN, the Izod changed from 6.1 t o 7.3 f t - l b / i n c h o f notch. However, a f t e r a c e r t a i n amount o f g r a f t was added, a d d i t i o n a l replacement o f SAN by g r a f t had v i r t u a l l y no e f f e c t on t h e Iaod impact v a l u e . E m p i r i c a l models were used t o r e l a t e the changes i n compos i t i o n t o r e s u l t a n t changes i n p r o p e r t i e s . The form o f the model used i s the s p e c i a l c u b i c which was developed by Scheffe ( 2 ) . Y

e

X

= i l

+

e

X

2 2

+

P

X

3 3

+

e

X

X

i2 l 2

+

e

X

X

B

+

!3 l 3

2 V 3

+

3

6

123

X

X 1

X 2

3

+ e where Y i s the p r o p e r t y o f i n t e r e s t ; X's are the pseudocomponent amounts o f g r a f t , SAN, and p i t c h , r e s p e c t i v e l y ; (B's are the c o e f f i c i e n t s t h a t d e s c r i b e the e f f e c t s o f the components; and e denotes the e r r o r term. The f o l l o w i n g equations r e s u l t e d from the m o d e l - f i t t i n g procedure: Izod = 7.39 X, + 6.08 X^ + 0.72 X + 2.54 X X - 5.31 X X 1 2 3 1 2 2 3 DTUL = 202.3 X + 211.8 X + 182.9 X - 22.8 X X - 22.2 X X 1 2 3 13 3 n

YS = 4367.2 X

l

n

+ 6087.5 X

2

n

+ 5071.5 X

3

+ 1440.0 X ^

+ 586.0

X ^

For each equation, two s t a t i s t i c s t h a t d e s c r i b e the adequacy of the equations were c a l c u l a t e d — t h e adjusted c o e f f i c i e n t o f det e r m i n a t i o n (3)(adjusted R ) and the standard e r r o r o f estimate (SEE). The adjusted R denotes the p r o p o r t i o n o f t h e v a r i a b i l i t y observed i n the p r o p e r t y t h a t was explained i n the terms o f t h e equation. The SEE i s a measure o f the unexplained v a r i a b i l i t y t h a t s t i l l e x i s t e d a f t e r the s i g n i f i c a n t e f f e c t s were taken i n t o account, Table I I I . 2



Graft, % SAN, % C T . Pitch, % Izod Impact, f t - l b / i n . DTUL, °F (264 p s i ) Y i e l d Strength, p s i

Composition and P r o p e r t i e s

45.0 55.0 0.0 6.1 213 6080

A

191 5740

45,0 42.5 12,5 2.1

B 50.0 45.0 5,0 4.9 202 5615

D 50,0 35.0 15.0 2,5 186 5385 53,5 38.0 8,5 4.4 197 5410

F

Blends

Blend E

of ABS - P i t c h

45.0 30.0 25.0 0.8 183 5065

C

Properties

Table I I

57,5 42.5 0.0 7.3 204 5280

G

57.5 30.0 12.5 3.9 188 5080

H

J 60.0 35.0 5.0 6.1 192 5035


70.0 30.0 0.0 7.4 205 4350

K


444

Table I I I Adequacy o f R e g r e s s i o n


Yield Izod DTUL Yield

Strength

Strength

Equations

A d j u s t e d R' 0.996 0.880 0.994

SEE 0.14 f t - l b / i n . o f n o t c h 3.4°F 37 p s i

A c o n v e n i e n t way o f d e p i c t i n g t h e e f f e c t s o f c o m p o s i t i o n on a p a r t i c u l a r p r o p e r t y i s through use of a response s u r f a c e ( 4 ) . A r e s p o n s e s u r f a c e i s a t o p o g r a p h i c a l - l i k e map t h a t shows c o m p o s i t i o n a l r e g i o n s i n w h i c h s i m i l a r p r o p e r t i e s c a n be e x p e c t e d . F i g u r e s 3 t h r o u g h 5 d e p i c t r e s p o n s e s u r f a c e s f o r I z o d , DTUL, and yield strength, respectively. These response s u r f a c e s were used t o determine compositions t h a t c o u l d be u s e d t o p r o d u c e s e v e r a l t y p e s and g r a d e s o f r i g i d ABS p i p e compound. F o r e x a m p l e , Type 4, G r a d e 1 p i p e must s a t i s f y t h e minimum r e q u i r e m e n t s shown i n T a b l e I V . Table IV R e q u i r e m e n t s o f Type 4, G r a d e 1 P i p e Compound Property Izod DTUL Yield

Strength

Specification >1 f t - l b / i n . >190°F >5000 p s i

of notch

T h e s e r e s t r i c t i o n s d e f i n e a r e g i o n w i t h i n t h e pseudocompon e n t s y s t e m where t h e p r o p e r t i e s c a n be e x p e c t e d t o s i m u l t a neously s a t i s f y a l l three s p e c i f i c a t i o n s . From a p r a c t i c a l p o i n t o f v i e w , t h e r e g i o n s h o u l d be c o n s e r v a t i v e l y d e f i n e d b e c a u s e e a c h r e g r e s s i o n equation i s s u b j e c t to a degree of e r r o r . Assuming 0.2 f t - l b / i n c h o f n o t c h , 5°F, and 50 p s i p r o v i d e s a t i s f a c t o r y s a f e t y m a r g i n s , t h e r e g i o n o f p o s s i b l e b l e n d s i s as shown i n F i g u r e 6. The a c t u a l c h o i c e w i t h i n t h i s r e g i o n may depend upon e c o nomic o r o t h e r c o n s i d e r a t i o n s . I f t h e c h o i c e i s s o l e l y depen d e n t upon m a x i m i z i n g t h e amount o f p i t c h i n t h e b l e n d , i t a p p e a r s t h a t , i n t e r m s o f p s e u d o c o m p o n e n t s , 0 p e r c e n t g r a f t and a p p r o x i m a t e l y 60 p e r c e n t SAN and 40 p e r c e n t p i t c h w o u l d be t h e s e l e c t e d blend. I n a b s o l u t e t e r m s , t h i s t r a n s l a t e s t o a b o u t 45 p e r c e n t g r a f t , 45 p e r c e n t SAN, and 10 p e r c e n t p i t c h . The maximum amounts o f p i t c h f o r o t h e r p i p e g r a d e s a r e shown i n T a b l e V.



.

WILT AND KOONS

ABS Pipe Compound Experiment

Figure 3.

Response surface—predicted Izod for compositions in experimental region.

Figure 4.

Response surface—predicted DTUL region.

for compositions in experimental


445



446

Figure 5.

Response surface—predicted yield strength for compositions in experimental region.

Figure 6.

Blends within experimental region suitable for Type 4 Grade 1 ABS pipe compound.


27.

WILT AND KOONS

ABS Pipe Compound

Experiment

447

Table V A l l o w a b l e P i t c h C o n t e n t o f ABS P i p e Compounds


P i p e M a t e r i a l I z o d , f t - l b / i n . DTUL, Y i e l d Maximum L i m i t i n g Designation of notch °F Str,psi Pitch,% Factor Type Type Type Type Type *

1, 1, 1, 2, 4,

Grade Grade Grade Grade Grade

1 2 3 1 1

3 6 3 4 1

180 180 220* 200 190

4000 4500 7000* 7000* 5000

Did not achieve w i t h i n the experimental

16 5

10

Izod, Izod

* * DTUL

region.

Conclusion An e x p e r i m e n t was d e s i g n e d t o d e t e r m i n e t h e amount o f c o a l t a r p i t c h t h a t c o u l d b e i n c o r p o r a t e d i n t o ABS p i p e compounds. Ten s e l e c t e d b l e n d s w e r e p r e p a r e d a n d c r i t i c a l p h y s i c a l p r o p e r t i e s d e t e r m i n e d . S t a t i s t i c a l techniques were used t o develop e m p i r i c a l equations r e l a t i n g the r e s u l t a n t p r o p e r t i e s t o blend composition. Scheffe" c a n o n i c a l p o l y n o m i n a l m o d e l s a n d r e s p o n s e s u r f a c e s provided a thorough understanding o f t h e mixture system. T h e s e m o d e l s w e r e u s e d t o d e t e r m i n e t h e amount o f c o a l - t a r p i t c h t h a t c o u l d b e i n c o r p o r a t e d i n t o ABS compounds t h a t w o u l d s t i l l meet ASTM r e q u i r e m e n t s f o r v a r i o u s p i p e - m a t e r i a l d e s i g n a t i o n s . Acknowledgment The b l e n d i n g and t e s t i n g w o r k was s u p e r v i s e d b y V. M. D i N a r d o a n d L . E. C a r l y s l e , J r . , r e s p e c t i v e l y .

I t i s understood t h a t t h e m a t e r i a l i n t h i s paper i s intended f o r g e n e r a l i n f o r m a t i o n o n l y and should n o t be used i n r e l a t i o n t o any s p e c i f i c a p p l i c a t i o n w i t h o u t i n d e p e n d e n t e x a m i n a t i o n a n d v e r i f i c a t i o n o f i t s a p p l i c a b i l i t y and s u i t a b i l i t y by p r o f e s s i o n a l l y q u a l i f i e d personnel. Those making u s e t h e r e o f o r r e l y i n g t h e r e o n assume a l l r i s k a n d l i a b i l i t y a r i s i n g f r o m s u c h u s e o r reliance.

American Chemical Society Library 1155 16th St., M.W. Provder; Computer Applications in Applied Polymer Science Washington, O.C.Society: 20036 ACS Symposium Series; American Chemical Washington, DC, 1982.

448


Literature Cited


1. Kurotori, J. S., Experiments with Mixtures of Compounds Having Lower Bounds, Industrial Quality Control, Vol 22, (1966), 592-596. 2. Scheffe, H., Experiments With Mixtures, Journal of Royal Statistical Society, Series B, Vol. 20, (1958), 344-360. 3. Marquardt, D. W. and Snee, R. D., Test Statistics for Mixture Models, Technometrics, Vol. 16, No. 4, (1974), 533-537. 4. Koons, G. F. and Heasley, R. H., Response Surface Contour Plots for Mixture Problems, Journal of Quality Technology, Vol. 13, No. 3, (1981), 207-214. RECEIVED May 4, 1982.


Computer Applications in Applied Polymer Science - American

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