Filler Reinforcement of Plasticized Poly(vinyl chloride)

13 Filler Reinforcement of Plasticized

Downloaded by UNIV OF TENNESSEE KNOXVILLE on November 14, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0134.ch013

Poly(vinyl chloride) RUDOLPH D. DEANIN, RAYMOND O. NORMANDIN, and GHANSHYAM J. PATEL Plastics Department, L o w e l l Technological Institute, L o w e l l , Mass. 01854

Plasticized poly(vinyl chloride) was compounded with 10100 phr of 6 μ calcium carbonate, 4.5 μ calcined kaolin aluminum silicate clay, 0.18 μ thermal carbon black, 0.012 μ fumed silica, chrysotile asbestos of 10 fibrils/gram and 200/1 aspect ratio, and / -inch long chopped glass roving. All six increased indentation resistance and modulus and decreased low-temperature flexibility, extensibility, and abrasion resistance. Some fillers, at some concentrations, improved tensile strength, resilience, and hot strength. In terms of overall improvement of properties, silica was best, followed by glass, asbestos, carbon black, clay, and calcium carbonate in that order. 14

1

2

I n c o r p o r a t i o n of fibers i n t o plastics g e n e r a l l y p r o d u c e s t r e m e n d o u s i m A

p r o v e m e n t s i n r i g i d i t y , s t r e n g t h , toughness, d i m e n s i o n a l s t a b i l i t y , a n d

often m a n y other properties, f o r m i n g t h e basis f o r t h e field of r e i n f o r c e d plastics ( J , 2).

P a r t i c u l a t e fillers of fine p a r t i c l e size a n d h i g h surface

areas, e s p e c i a l l y c a r b o n b l a c k s , i m p r o v e most properties of elastomers g r e a t l y a n d a r e therefore r e f e r r e d to as r e i n f o r c i n g fillers (3, 4, 5 ) . I n plastics, h o w e v e r ,

p a r t i c u l a t e fillers g e n e r a l l y result i n m u c h less i m

p r o v e m e n t i n properties a n d a r e c o m m o n l y c o n s i d e r e d l o w - c o s t extenders (6,7,8,9).

A c t u a l l y t h e i r effects o n p r o c e s s i n g a n d p r o p e r t i e s are m u c h

m o r e i m p o r t a n t t h a n t h e i r effects o n v o l u m e cost, a n d thus t h e y s h o u l d b e c o n s i d e r e d p r i m a r i l y f r o m this p o i n t of v i e w . P l a s t i c i z e d p o l y ( v i n y l c h l o r i d e ) is i n t e r m e d i a t e b e t w e e n c o n v e n t i o n a l plastics a n d elastomers a n d m i g h t b e d e s c r i b e d as a t h e r m o p l a s t i c elasto-plastic (10, 11). F i l l e r s a r e f r e q u e n t l y a d d e d t o i t , p a r t i c u l a r l y i n f l o o r i n g a p p l i c a t i o n s (8). Consequently it provides a useful starting p o i n t f o r s t u d y i n g t h e effects of fillers o n properties a n d f o r i d e n t i f y i n g 128 Deanin and Schott; Fillers and Reinforcements for Plastics Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

13.

DEANIN

E T

AL.

Plasticized

129

PVC

those p r o p e r t i e s w h i c h are i m p r o v e d b y fillers a n d m i g h t therefore

be

d e f i n e d as reinforcements. Experimental


F i l l e d plasticized poly (vinyl chloride) composition:

samples

Stauffer S C C - 6 8 6 p o l y ( v i n y l c h l o r i d e ) dioctyl phthalate plasticizer N L T r i b a s e l e a d sulfate s t a b i l i z e r filler

of

the

following

100 50 3 X

w e r e p r e p a r e d b y w e i g h i n g the i n g r e d i e n t s i n t o a beaker, m i x i n g w i t h a s p a t u l a u n t i l h o m o g e n e o u s , a n d f u s i n g a n d m a s t i c a t i n g 5 m i n at 1 6 0 ° C o n a 6 i n c h X 12 i n c h differential-speed t w o - r o l l m i l l . M i l l e d sheets w e r e s t a c k e d a n d pressed 5 m i n at 166 ° C to f o r m sheets Vs i n c h t h i c k . T h e s e w e r e c u t i n t o test samples a n d e v a l u a t e d a c c o r d i n g to s t a n d a r d A S T M m e t h o d s w h e r e v e r possible. T h e fillers s t u d i e d r a n g e d f r o m c o n v e n t i o n a l n o n - r e i n f o r c i n g to r e i n f o r c i n g p a r t i c u l a t e fillers a n d o n to short a n d l o n g fiber reinforcements. Calcium Carbonate. C a l c i u m C a r b o n a t e C o . G - W h i t e , 6-μ m e d i a n p a r t i c l e size, r e c o m m e n d e d for p l a s t i c i z e d p o l y ( v i n y l c h l o r i d e ) . Clay. H a r w i c k 5 C c a l c i n e d k a o l i n a l u m i n u m s i l i c a t e , 4.5-μ, average p a r t i c l e size, r e c o m m e n d e d for w i r e a n d c a b l e i n s u l a t i o n a n d other plastics c o m p o u n d i n g a p p l i c a t i o n s . Carbon Black. C a b o t S t e r l i n g F T t h e r m a l b l a c k , 0.18-μ d i a m e t e r . Silica. C a b o t C a b - O - S i l M - 5 f u m e d s i l i c a , 0.012-/X p a r t i c l e size. L o a d ings b e y o n d 30 p h r ( parts p e r h u n d r e d of r e s i n ) w e r e not p o s s i b l e w i t h the present t e c h n i q u e . Asbestos. U n i o n C a r b i d e C a l i d r i a R G - 1 4 4 c h r y s o t i l e asbestos, 1 0 fibrils p e r g r a m , 2 0 0 / 1 aspect r a t i o , r e c o m m e n d e d f o r r e i n f o r c i n g v i n y l s . L o a d i n g s b e y o n d 60 p h r w e r e not possible w i t h the present t e c h n i q u e . Glass. P i t t s b u r g h P l a t e G l a s s y 2 - i n c h l o n g c h o p p e d glass r o v i n g 3129. L o a d i n g s b e y o n d 30 p h r w e r e not possible, a n d even these w e r e not u n i f o r m , w i t h the present t e c h n i q u e . T h e results are p r e s e n t e d i n F i g u r e s 1-8. I n a l l figures, the f o l l o w i n g c o d e is u s e d : 1 4

C a l c i u m carbonate Clay — · — — · •— Carbon black Silica Asbestos Glass

· —

· —

CC CI CB S A G

Results Hardness. P l a s t i c i z e d v i n y l s are g e n e r a l l y j u d g e d first b y i n d e n t a t i o n hardness.

T h i s w a s m e a s u r e d as Shore D u r o m e t e r hardness D - 2 a c c o r d

i n g to A S T M D - 2 2 4 0 ( F i g u r e 1 ) .

A l l six fillers i n c r e a s e d hardness, a p -

Deanin and Schott; Fillers and Reinforcements for Plastics Advances in Chemistry; American Chemical Society: Washington, DC, 1974.


Figure 1.

Effect of fillers on hardness

p r o x i m a t e l y i n p r o p o r t i o n to t h e i r c o n c e n t r a t i o n .

G l a s s w a s the most

effective, f o l l o w e d b y s i l i c a , asbestos, c l a y , c a r b o n b l a c k , a n d c a l c i u m carbonate.

T h i s p r o p e r t y is i m p o r t a n t w h e n f u r n i t u r e or p o i n t e d heels

rest o n v i n y l

flooring.

Modulus. P l a s t i c i z e d v i n y l s are g e n e r a l l y f o r m u l a t e d to a specified softness as m e a s u r e d b y the tensile m o d u l u s at 1 0 0 % e l o n g a t i o n .

This

w a s m e a s u r e d a c c o r d i n g to A S T M D - 6 3 8 , u s i n g samples w i t h flat sect i o n 2.32 inches l o n g a n d a test s p e e d of 2 inches p e r m i n u t e ( F i g u r e 2 ) .

Fillers,

Figure 2.

PHR

Effect of fillers on modulus


13.

DEANIN

ET

Plasticized

AL.

131

PVC

A l l six fillers i n c r e a s e d m o d u l u s , a p p r o x i m a t e l y i n p r o p o r t i o n to t h e i r c o n c e n t r a t i o n . G l a s s w a s the most effective, f o l l o w e d b y s i l i c a , asbestos, clay, carbon black, a n d c a l c i u m carbonate effect).

( t h i s last h a d b a r e l y

U n f o r t u n a t e l y the stiffest compositions

d i d not reach

e l o n g a t i o n a n d thus c o u l d not b e i n c l u d e d i n this p l o t .

any

100%

T h i s stiffening

effect m a y b e e x p l a i n e d b y : ( a ) r e f u s a l of h i g h m o d u l u s fibers to p e r m i t extension of the soft p l a s t i c m a t r i x ; ( b )

interference of

high-modulus


r i g i d filler surfaces w i t h the n o r m a l l y free m o b i l i t y of t h e soft p l a s t i c m o l e c u l e s ; or ( c )

a d s o r p t i o n of p l a s t i c i z e r onto the h i g h - s u r f a c e

filler

p a r t i c l e s , l e a v i n g m u c h less p l a s t i c i z e r a v a i l a b l e to soften the p l a s t i c m a t r i x . P r a c t i c a l l y , of course, filler l o a d i n g offers a n e c o n o m i c a l w a y to increase the stiffness of p l a s t i c i z e d p o l y ( v i n y l c h l o r i d e ) to a n y d e s i r e d l e v e l , for e a c h i n d i v i d u a l a p p l i c a t i o n . Low-Temperature

Flexibility.

T h e low-temperature

f l e x i b i l i t y of

p l a s t i c i z e d v i n y l s is g e n e r a l l y j u d g e d b y the C l a s h - B e r g l o w - t e m p e r a t u r e t o r s i o n a l m o d u l u s test A S T M D - 1 0 4 3 , a n d most c o m m o n l y r e p o r t e d as T

F

the t e m p e r a t u r e at w h i c h the m a t e r i a l has a t o r s i o n a l m o d u l u s

45,000 p s i ( F i g u r e 3 ) .

of

A l l six fillers c a u s e d l o w - t e m p e r a t u r e stiffening

of p l a s t i c i z e d v i n y l , a p p r o x i m a t e l y i n p r o p o r t i o n to t h e i r c o n c e n t r a t i o n . G l a s s w a s w o r s t , f o l l o w e d b y s i l i c a a n d asbestos, c l a y , c a r b o n b l a c k , a n d c a l c i u m carbonate.

T h e o v e r a l l effect, 11° to 17 ° C at 100 p h r of

fillers,

w a s serious e n o u g h to present a p r o b l e m i n l o w - t e m p e r a t u r e a p p l i c a t i o n s .


132

FILLERS

Tensile Strength.

AND

REINFORCEMENTS FOR

PLASTICS

W h i l e most p l a s t i c i z e d v i n y l p r o d u c t s are not

g e n e r a l l y u s e d u p to t h e i r u l t i m a t e tensile strength, this is the c o m m o n strength m e a s u r e m e n t m a d e o n s u c h v i n y l compositions.

most

It w a s

tested a c c o r d i n g to A S T M D - 6 3 8 as d e s c r i b e d a b o v e ( F i g u r e 4 ) .

The

i m p r o v e m e n t , caused b y glass fibers w a s e x p e c t e d a n d s h o u l d p o s s i b l y h a v e b e e n h i g h e r w i t h o p t i m u m processing.

The improvement

caused


b y finely p o w d e r e d s i l i c a w a s u n e x p e c t e d a n d is t h e sort of b e n e f i c i a l

3000

2 500

2000

40 Filler,

Figure 4.

100 PHR

Effect of fillers on tensile strength

result n o r m a l l y l a b e l l e d as r e i n f o r c e m e n t ; w i t h h i g h e r

concentrations

a n d s u i t a b l e processing, i t m i g h t be of major p r a c t i c a l significance. A l l other

fillers

decreased tensile s t r e n g t h — a m i n o r p r o b l e m for asbestos,

b u t i n c r e a s i n g l y serious for c l a y , c a r b o n b l a c k , a n d c a l c i u m c a r b o n a t e i n that order.

T o p r e v e n t this sacrifice of strength, i t w o u l d b e of interest

to s t u d y surface finishes w h i c h w o u l d increase i n t e r f a c i a l b o n d i n g

be-

t w e e n the fillers a n d the p l a s t i c m a t r i x , as has b e e n d o n e i n m a n y other r e i n f o r c e d plastics systems ( J , 2 ) . Extensibility. U l t i m a t e e l o n g a t i o n w a s m e a s u r e d a c c o r d i n g to A S T M D - 6 3 8 as d e s c r i b e d a b o v e ( F i g u r e 5 ) .

W h i l e plasticized v i n y l products

are not n o r m a l l y stretched to the b r e a k i n g p o i n t , this p r o p e r t y is g e n e r a l l y m e a s u r e d a n d often erroneously t a k e n as a measure of softness of the c o m p o s i t i o n .

I n this s t u d y , a l l of the fillers l o w e r e d u l t i m a t e e l o n g a -

t i o n , a p p r o x i m a t e l y i n p r o p o r t i o n to t h e i r c o n c e n t r a t i o n . G l a s s w a s most effective, f o l l o w e d b y s i l i c a a n d asbestos, c l a y , c a r b o n b l a c k , a n d c a l c i u m c a r b o n a t e i n that order.

I n a p p l i c a t i o n s w h e r e h i g h e x t e n s i b i l i t y is of

p r a c t i c a l i m p o r t a n c e , the use of fillers c o u l d thus be a p r o b l e m .


13.

DEANIN

ET

AL.

Plasticized

133

PVC


400 r

0

L

0

—

'

20

Figure 5.

«

40 Filler,

»

60 PHR

Effect of fillers on

1

»

80

100

extensibility

Resilience. R u b b e r y r e s i l i e n c e was m e a s u r e d b y r e b o u n d a c c o r d i n g to A S T M D - 2 6 3 2 , s t a c k i n g V s - i n c h sheets one to five layers t h i c k a n d r e c o r d i n g the m a x i m u m r e b o u n d f r o m e a c h series

(Figure 6).

Low

c o n c e n t r a t i o n of fillers p r o d u c e d some u n e x p e c t e d increase i n resilience

Filler,

Figure 6.

PHR

Effect of fillers on resilience


134

FILLERS

AND

REINFORCEMENTS FOR

w h i l e h i g h c o n c e n t r a t i o n p r o d u c e d a decrease.

PLASTICS

Theoretical explanation

m u s t a w a i t m o r e i n t e n s i v e u n d e r s t a n d i n g of the m e c h a n i s m s

involved.

P r a c t i c a l l y , a l l t h e v i n y l f o r m u l a t i o n s i n this s t u d y h a d o n l y

15-21%

r e b o u n d , i n d i c a t i n g h i g h hysteresis; this means that at the s p e e d of this test ( a b o u t 6 m p h )

most of t h e m e c h a n i c a l energy of i m p a c t w a s

s o r b e d b y i n t e r n a l i n t e r m o l e c u l a r f r i c t i o n a n d c o n v e r t e d i n t o heat. s u c h compositions

are of interest for c r a s h p a d d i n g , shock

absorption,

p a c k a g i n g of d e l i c a t e p r o d u c t s , v i b r a t i o n d a m p i n g , a n d noise Downloaded by UNIV OF TENNESSEE KNOXVILLE on November 14, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0134.ch013

ab-

Thus

damping

(12).

CM 0

1

Figure 7.

.

40 Filler,

60 PHR

Effect of fillers on abrasion

Abrasion Resistance. D-1044

1

20

A b r a s i o n was

using C S - 1 7 wheels

1

100

resistance

studied according

a n d a 1000-gram

m e a s u r e d after 5000 cycles ( F i g u r e 7 ) .

1

80

to

ASTM

l o a d ; w e i g h t loss

was

A l l six fillers i n c r e a s e d a b r a s i o n

loss, a p p r o x i m a t e l y i n p r o p o r t i o n to t h e i r c o n c e n t r a t i o n .

Glass caused the

greatest loss, f o l l o w e d b y asbestos, w i t h c a r b o n b l a c k , c a l c i u m c a r b o n a t e , a n d c l a y g r o u p e d closely together, a n d s i l i c a ( h a r d to j u d g e because of insufficient d a t a ). T h i s loss of resistance to a b r a s i o n c o u l d b e a p r o b l e m i n many applications. vinyl

flooring,

O n the other h a n d , the e x c e p t i o n a l d u r a b i l i t y of

at s t i l l h i g h e r l o a d i n g s , suggests that i t m a y not be

serious as i t appears. H o t Strength. hanging 2 inch X

as

T h i s discrepancy requires further study.

Zero s t r e n g t h t e m p e r a t u r e ( Z S T ) w a s m e a s u r e d 1 inch X

by

% i n c h samples i n a c i r c u l a t i n g a i r o v e n ,

i n c r e a s i n g t h e t e m p e r a t u r e l ° C / m i n u t e , a n d o b s e r v i n g the t e m p e r a t u r e


13.

DEANIN

E T

AL.

Plasticized

135

PVC

at w h i c h e a c h s a m p l e c o u l d no l o n g e r s u p p o r t its o w n w e i g h t a n d f e l l to the floor o f the o v e n ( F i g u r e 8 ) . W h e r e a s u n f i l l e d p l a s t i c i z e d v i n y l f a i l e d at 2 0 0 ° C a n d l o w concentrations of s o m e w h a t , h i g h e r concentrations

fillers

of f o u r

decreased fillers

this t e m p e r a t u r e

produced

marked i m -

p r o v e m e n t i n h o t strength, so that samples r e m a i n e d s e l f - s u p p o r t i n g u p b e y o n d the 285 ° C l i m i t of t h e test.

S i l i c a a n d asbestos p r o d u c e d this

effect even at 30 p h r w h i l e c a r b o n b l a c k a n d c l a y also p r o d u c e d it at


100 p h r . T h e n a t u r e of the d i p at l o w concentrations w a s mysterious a n d r e q u i r e s f u r t h e r s t u d y . T h e t r e m e n d o u s i m p r o v e m e n t at h i g h e r c o n c e n trations m i g h t arise f r o m the effect of t h e fillers i n i n c r e a s i n g m e l t v i s cosity. It s h o u l d b e s t u d i e d for its p r a c t i c a l v a l u e i n i n c r e a s i n g t h e u p p e r l i m i t of the use temperatures for p l a s t i c i z e d v i n y l p r o d u c t s .

Filler,

Figure 8.

PHR

Effect of fillers on hot strength

Conclusions A l l six fillers i n c r e a s e d i n d e n t a t i o n resistance a n d m o d u l u s . fillers,

Some

at some concentrations, also i m p r o v e d tensile s t r e n g t h , r e s i l i e n c e ,

a n d hot strength. A l l fillers decreased

low-temperature

flexibility,

ex-

t e n s i b i l i t y , a n d a b r a s i o n resistance. I n terms of o v e r a l l p r o p e r t y i m p r o v e m e n t , s i l i c a was best, f o l l o w e d b y glass, asbestos, c a r b o n b l a c k , c l a y , a n d c a l c i u m carbonate. O p t i m u m p r o c e s s i n g t e c h n i q u e s to i n c o r p o r a t e l a r g e r concentrations of glass fibers a n d s i l i c a s h o u l d i m p r o v e properties e v e n further.

T h u s specific

fillers

P r e s u m a b l y , p r o p e r surface

c a n b e chosen for specific i m p r o v e m e n t s . finishes

o n the

fillers

c o u l d increase t h e i r


136

FILLERS A D R E I N F O R C E M E N T S F O R PLASTICS

i n t e r f a c i a l b o n d i n g to t h e p l a s t i c m a t r i x a n d thus e n h a n c e strength a n d abrasion

resistance.


Literature Cited 1. Lubin, G., "Handbook of Fiberglass and Advanced Plastics Composites," Van Nostrand Reinhold, New York, 1969. 2. Mod. Plastics Encyc. (1972) 49 (10A), 365-382. 3. Snyder, J. W., Leonard, M. H., in "Introduction to Rubber Technology," M. Morton, Ed., Chap. 8, Reinhold, New York, 1959. 4. Wolf, R. F., Ibid., Chap. 9. 5. Kraus, G., "Reinforcement of Elastomers," Interscience, New York, 1965. 6. Boonstra, Β. B., Ibid., Chap. 16. 7. Brydson, J. Α., "Plastics Materials," pp. 181-183, Van Nostrand, New York, 1966. 8. Sarvetnick, Η. Α., "Polyvinyl Chloride," pp. 107-113, 219-222, Van Nos trand Reinhold, New York, 1969. 9. Mod. Plastics Encyc. (1972) 49 (10A), 382-394. 10. Sarvetnick, Η. Α., "Polyvinyl Chloride," Chap. 5, Van Nostrand Reinhold, New York, 1969. 11. Brydson, J. Α., Ibid., Chap. 9. 12. Deanin, R. D., Shah, S. B., Kapasi, V. C., Pfister, D. H., Amer. Chem. Soc., Div. Polym. Chem., Preprints (1973) 14 (2), 861. RECEIVED October 11, 1973. Based on a M.Sc. Thesis by G. J. Patel, Lowell Technological Institute.


Filler Reinforcement of Plasticized Poly(vinyl chloride)

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