ELASTOMER-RESIN BLENDS ACRYLONITRILE TYPE SYNTHETIC RUBBER AND POLYVINYL CHLORIDE RESINS D. W. YOUNG, D. J. BUCKLEY, ANDR. G. NEWBERG Standard Oil Development Company, Eliaabeth, N. J .
L. B. TURNER Enjay Company, Inc., New York,N. Y.
Special techniques are presented for compounding and curing of butadiene-acrylonitrile type copolymers with high molecular weight polyvinyl chloride polymers and vinylidene chloride polymers. The butadiene-acrylonitrile copolymers, as well as butadiene-methyl acrylonitrile copolymer studied as vinyl-resin plasticizers, varied in molecular weight and nitrile content. Some of the rubberlike copolymers used are known commercially as Perbunan NS 26, and Perbunan 35NS 90. The NS polymers are stabilized with a nontoxic and nonstaining antioxidant. About 70 synthetic elastomer-vinyl type blends were made on a laboratory rubber mill and then cured under heat and pressure. The following tests were carried out: 100% modulus, tensile stress, ultimate elongation, Shore durometer hardness, brittle temperature, specific gravity, weight loss, heat aging at 250"F., light aging, stiffness, and volume increase in A.S.T.M. reference fuels No. 1and
2, A.S.T.M. Oil No. 3, and water. I t was found that the butadiene-acrylonitrile copolymers containing 26 to 35% acrylonitrile gave cured polyvinyl resin-rubber blends with higher tensile strength, higher 100% modulus, and greater ultimate elongation to break than rubbers containing less acrylonitrile. However, the improved properties were found only when the final products contained from 13 to 25% synthetic rubber. A t higher concentrations of nitriletype synthetic rubber the tensile and modulus values for the cured rubber-resin blends did not vary with acrylonitrile content. Some of the cured products had excellent thermal and light stability, toughness, and chemical inertness. Certain precautions must be followed in control of temperature of mixing and in the selection of c o m pounding ingredients for the rubber-resin blends, such as accelerators and plasticizers, to obtain these improved properties.
T
resin blends. It was also found that some of the blends had certain limitations as evaluated in a laboratory blocking test. T o improve this property i t was decided to study cured blends, as by this procedure surface tack is usually reduced. In this paper compounding techniques are given as well as laboratory test data on sulfur cured Buna N-polyvinyl-dioctyl phthalate blends. Most of the work was done with Perbunan NS polymers and Vinylite, VYNW. However, in a limited way the investigation covered also modified Buna N polymers such as low molecular weight 1,3-butadiene-acrylonitrile copolymer oils and l,%butadiene-methacrylonitrile solid resinlike copolymers. The Perbunan N S polymers are a commercial class of 1,3-butadiene-acrylonitrile copolymers stabilized with a nonstaining antioxidant (stabilizer 8567) and Vinylite, VYNW, is a high molecular weight copolymer formulated from vinyl chloride and vinyl acetate (95 to 5%). For comparative data and general background, tests were made on a few Perbunan NS-polyvinylidene chloride blends. Another phase of the present investigation covers the preparation of an experimental stock by the use of a nonsulfur type cure or tetramethyl thiuram disulfide cure on loaded Perbunan-vinyl compositions plasticized with a nonmigrating polyester plasticizer (Paraplex G-25). In this work particular emphasis was placed on flame resistance, low temperature behavior, and heat aging properties, specifically embrittlement and elongation retention.
HE commercial advent in recent years of special purpose
synthetic rubbers on the one hand and widely accepted plastics on the other hand have resulted in a merger of the rubber and the plastics industry. In overlapping production and marketing effort both industries have cooperated in engineering new and improved products. To cite an example, mixtures of vinyl resins and 1,3-butadiene-acrylonitrile rubbers have been combined to form tough heat resistant products. A further advance in this field is achieved by vulcanizing the polymer in the mixture thereby attaining resilience, good light aging, and excellent chemical and solvent resistance. These new cured rubber-vinyl blends are being used to form raincoats and a variety of other products. Saeger (Q), Thompson (IO), Wolfe (I@, and others (4) suggest the combination of vinyl resins, including polyvinyl chloride with rubber. As the synthetic rubber art has developed, numerous suggestions have been made to blend the newer synthetic rubbers with vinyl resins. An article by Nowak and Hofmeier (7) is typical. As early as the spring of 1938, efforts were made by I. G. Farbenindustrie to develop a market in this country for Buna N rubber, copolymers of 1,3-butadiene, and acrylonitrile. It was reported that Perbunan could be blended with polyvinyl chloride (1). Some 10 years ago, Badum, in his studies (g), formulated Buna N rubber-polyvinyl chloride blends. The products were evaluated as ozone-resistant cable insulations. Also, Henderson (3) experimented with Buna N-polyvinyl chloride resin blends. From that time until the present, these novel blends have been mentioned in the literature only rarely. In 1946 and 1947 Winkelman (11),Moulton (6), Kenney (6), and Pittenger with Cohan (8)reviewed the general subject of rubber-resin blends and some results on Buna N-resin products were listed. Recently, Young, Newberg, and Howlett ( I J ) , reported on the physical properties of a number of uncured Buna N-vinyl
401
EXPERIMENTAL
The polyvinyl chloride-vinyl acetate copolymer (Vinylite, VYNW) chosen for the work was obtained from the Bakelite Corporation and the vinylidene chloride polymers (Saran) from the Dow Chemical Company. The dioctyl phthalate was supplied by the Ohio Apex Company, Incorporated, and Paraplex G-25 by the Resinous Products and Chemical Company. The basic formulation was as follows:
Vol. 41, No. 2
INDUSTRIAL AND ENGINEERING CHEMISTRY
402
1000 FIGURE 2
100%MODULUS V A L U E S FOR C U R E D P E R B U N A N - V Y N W - D I O C T Y L P H T H A L A T E BLENDS
h \ t\
C U R E D 3 0 ' A T 287'F
it
--
X\
zoo0
3
17001
J
z
1400
STOCK T Y P E - V Y N W I00,STEARIC ACID 3, LITHARGE 1.5, I 5, OIOCTYL PHTHALATE 50, PERBUNAN VARIE0,SULFUR 2 PARTS PER 100 PARTS PERBUNAN
STOCK T Y P E - V Y N W IO0,STEARIC ACID 3 , LITHARGE 1.5. D I O C T Y L PHTHALATE 50,PERBUNAN VARIED SULFUR 2 PARTS PER 100 PARTS PER BUN AN ,BENZOTHIAZYLDISULFIDE 2 PARTS O F PERBUNAN
LEGEND
0 0 X
~
~
~
X
~
PERBUNAN 18
. PERBUNAN
-
26NS 90
PERBUNAN 3 5 N S 9 0
FIGURE I
530
T E N S I L E S T R E N G H OF C U R E D P E R B U N A N - V Y N W P H T H A L A T E B L E N D S CURED
20d
C 0
LEGEND PERBUNAN 18 N S 90 PERBUNAN 2 6 N S 9 0 PERBUNAN 3 5 N f 9 0
- DIOCTYL
I
2 00
30' A T 2 8 7 'F.
I
I 30
20
10
40
PER CENT PERBUNAN IN C O M P O U N D 10
20
30 40 P E R CENT PERBUNAN IN COMPOUND
Parts by Weight 100 1 5 3
Vinyl type resin Vinyl stabilizer and/or accelerator Stearic acid Diootyl phthalate Perbunan NS polymers Sulfur Benzothiazyl disulfide
60.
Varied Vaned Varied
The synthetic rubber plasticizer, such as Perbunan, was varied 'from 25 to 200 parts, based on 100 parts by weight of vinyl resin. In most of the work fillers were omitted from the formulation so that the compound properties would be a function only of the kind and amount of plasticizcr used. Litharge and other products were used as stabilizers for the vinyl resin (as well as an accelerator for the sulfur cure); the stearic acid used as a parting agent or lubricant facilitated easy release of the stock from the hot mill and mold. The synthetic elastomers studied were: Perbunan
35XS 140, Perbunan 35NS 90, Perbunan 26XS 100, Perbunan 26KS 90, Perbunan 26NS 60, Perbunan 26SS 40, Perbunan 26 low molecular weight oil (76-40 oil), Perbunan 18, and an experimental Buna N that contained 55% 1,a-butadiene and 45y0 methacrylonitrile. As the Perbunan number increases the acrylonitrile in the copolymer increases (within small operating variations) as follows: Perbunan 18, 20% acrylonitrile; Perbunan 26, 28% acrylonitrile; and Perbunan 35, 35y0 acrylonitrile. The NS indicates that the copolymer contains the nonstaining antioxidant (8567) and the number after SS reports the approximate 212 F., 15-minute Nooney viscosity. The Perbunan 18 used had it Mooncy viscosity of 80 and the 1,3-butadiene-methacrylonitrile copolymer a Mooney viscosity of 40. The tests carried out on a number of the products were as follows: 100yo modulus, tensile stress, ultimate elongation, Shore durometer hardness, brittle temperature, specific gravity, heat aging at 250' F., light aging, stiffncss, blocking temperature,
i FIGURE 4
FIGURE 3
OF
LOW TEMPERATURE PROPERTIES
U L T I M A T E ELONGATION VS. N I T R I L E
CONTENT OF PEREUNAN POLYMERS IN CURED PERBUNAN - V Y N W - OIOCTYL P H T H A L A T E B L E N D S C U R E D 30' AT 2 8 7 OF
CURED P E R E U N A N - V Y N W -
DIOCTYL PHTHALATE BLENDS
-10
C U R E D 3 0 ' AT 287'F.
-20
iL
w (r
-30
0
c
0 -PESBUNAN
Y
2c
e - PERBUNAN
18
2 6 N S 90 'A- PERBUhAN 3 5 N S 90
400
a
. .
e .
cz c& Y
x
-40 I-
LEGEND PERBUNAN i 8 PERBUNAN 2 6 ~ s90 PERBUNAN 3 5 N S 90
t
Y
c
r
E
m
STOCK T Y P E * V Y N W IO0,STEARIC ACID 3 , LITHARGE 1.5, D I O C T Y L PHTHALATE 50,PERBUNAN VARIEO, SULFUR 2 PARTS PER 100 PARTS PERBUNAN, BENZOTHlAZYLDiSULFlDE 2 PARTS 100 PARTS O F PER BUNAN
I 20
I 30
PER CENT PERBUUAN IN COMPOUND
I 40
-50
-60
- 70 -80
I
I
I
20
30
40
PER CENT PERBUNAN I N COMPOUND
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
February 1949
CYCLE TABLE I. EFFECTOF VULCANIZING Compound
Parts b y Weight 100
VYNW
100 3 2 2 1.5 50
Perbunan 35 NS 90 Stearic acid Sulfur Benaothiazyl disulfide Litharge Dioctyl phthalate
GO
Cure time, min. Temperature F. Tensile. lb./sb. in.
15
30
15
~
5
-15
-30
1700 1I
color, and volume increase in A.S.T.M. reference fuels No. 1 and 2, A.S.T.M. Oil No. 3, and water.
403
Brittle Temperature. The instrument used to determine these Thespecivalues was that described under A.S.T.M. D 74-41'. mens were allowed t o condition 25 minutes in air t o reach equilibrium temperature in the bath prior t o testing. Blocking Temperature. These results were obtained by the use of A.S.T.M. procedure D 884-481'. Stiffness Index. By the use of the Tinius-Olsen Tour-Marshal tester (A.S.T.M. D747-431') the stiffness index in pounds per square inch was determined on a number of the products a t 75 F. Volume Increase. These values were obtained in standard laboratory fluids a t room temperature. SR-6 or A.S.T.M. D 471-46T reference fuel No. 2 was formulated from 60% diisobutylene, 20% toluene, 5% benzene, and 15% xylene. SR-10 or A.S.T.M. reference fuel No. 1 is pure diisobutylene. A.S.T.M. Oil No. 3 is a low volume increase mineral oil with an aniline point of 70 C. O
DISCUSSION OF RESULTS PREPARATION O F SAMPLES
Milling Procedure. I n the h a 1 milling procedure as developed in this work the ingredients, with the exception of the Perbunan, sulfur and accelerator, were weighed out in a Pyrex beaker and dry biended by hand. After blending, the wet su arlike mixture then was changed t o a 6 X 12 inch laboratory rub%er mill heated with steam to about 280 to 300 F. The resin was fluxed, two t o three minutes, and allowed t o mill with a tight rolling bank for 5 minutes with occasional cutting. To this plastic at 280" F. was added the rubber. Mill mixing was continued for 12 minutes at 280' F. The batch then was sheeted off the mill a t 0.075 to 0.15 inch thickness. The mixture was allowed to cool to 160 ' to 180 O F. and placed on a rubber mill a t the same temperature. To the system was slowly added sulfur and accelerator. Milling was continued a t a temperature below 200 F. for 8 minutes. Molding Method. This operation was carried out in a stand' ard A.S.T.M. four-cavit mold (D 15-41), yielding slabs 6 X 6 X 0.75 inch. After a stuc& of the effect of time and temperature (Table I) the molding and curing cycle was held at 15 and 30 minutes, respectively, a t 287" F. with a ram pressure of 900 pounds per square inch. Each test slab was allowed to cool to 270" F. under pressure in the mold before being removed. By this procedure no distortion or tearing was obtained. All samples were allowed to rest at least 24 hours at room temperature before testing.
Effect of Mooney Viscosity. In Table I1 results are presented on Vinylite, W N W blends plasticized with several Perbunan 26 polymers and dioctyl phthalate. These data show, based on tensile, ultimate elongation, crescent tear, and brittleness tes~ts,that the Perbunan 26 polymer cure blends studied have about the
O
PERBUNAN 3 6 N S 90 230 FIGURE
5
B L O C K I N G T E M P E R A T U R E FOR P E R B U N A N
220
O
V Y N W BLENDSCURED
-
3O'AT Z87'F
I
w
a
2
210
w
ce D
i
.
6
200 STOCK T Y P E - V Y N W 100, STEARIC ACID 3 LITHARGE 1.5.
Y)
m
-7
PERBUNAN VARIED, SULFUR 2 PARTS PER 100 PARTS PERBUNAN, BENZOTHlAZYLDlSULFlDE 2 PARTS PER 100 PARTS OF PERBUNAN
190
y.
*w 3 LL
TEST METHODS
t
Tensile Stress, 100% Modulus, and Ultimate Elongation. These tests were made on a Model L-3 Scott tester a t 75" F. and and about 55% relative humidity. The rate of jaw separation was 20 inches per minute. For measurement of elongation, the specimens were bench marked, with a 1-inch die, the grips were adjusted a t zero load 0.75 inch apart, and the elongation was measured by means of a decimal scale held close to the specimen. Shore Durometer Hardness. These values were obtained using the Shore A durometer (A.S.T.M. D 676-44T). Multiple readings were taken on each specimen.
\
180
w
E
" z
170
0 -I
0 - PERBUNAN
160
X
-
2 6 N S 90
PERBUNAN 3 5 1 5 90
I50
20
30
40
PER CENT PERBUNAN IN COMPOUND
TABLE11. EFFECTOF MOONEY VISCOSITYOF PERBUNAN 26 POLYMERS ON PHYSICAL PROPERTIES OF CUREDBLENDS Btock No. VYNW Stearic acid Benzothiaayl disulfide Sulfur Litharge Dioctyl phthalate Perbunan 26NS 100 Perbunan 26NS 90 Perbunan 26NS 60 Perbunan 26NS 40 Perbunan 26 oil
1 100 3 1 1 1.5
50
60
... ... ...
3
100 3 1 1 1.5 50
...
...
50
...
30 15 15 1.206 1.204 30 1.206 1.198 30 1.194 2070 1860 2070 1770 1,99,0 650
fino
E m
440
366
370
-. 370
..-"
64
67
65
65
64
230 -50
210 -50
210 -50
210 -50
210 -50
-1"
370
15
Is321.204 !2'
30 1.203
... ...
m --
151.207 301.206 15 1.280 30. 1.282 1 ~ 3 7 ~ 1&12 1580 1900 a"
'0"
d
230
240
60
59
59
54
230 -40
230 -40
170 4-10
180 +10
430
VU"
1
1.5 ... ...
..*
450
VY"
6 100 3 1
... ... .... .. 50
... ...
50
57n
5 100 3 1 1 1.5 50
4 100 3 1 1 1.5 50
... ... ...
... ... ...
...
Cure time a t 287' F., min. 15 Speoifio gravity 1.209 Tensile lb./aq. in. 1870 ModulAs a t 100%. lb./so. in. 640 Ultimate elongat'on, % 420 Uu..ometer hardness (instant) 64 Crescent tear a t 75' F., lb./in. 240 Brittle temperature, F. -50
2 100 3 1 1 1.5 50 ... 50
...... 0
io' ' '
lllYIY
94
93
160
$io'.-
f30
INDUSTRIAL AND ENGINEERING CHEMISTRY
404
TABLE 111. 1 Stock No. VYNW 100 20 Perbunan 18 3 Stearic acid 0.5 Sulfur Benzothiazvl disulfide 0.5 Litharge 1.5 Dioctyl phthalate 50 Perbunan 18 in compound, % 13.8 Dioctyl phthalate in compound, % 27.7 Total plasticizer, % 41 5 1.196 Specific gravity Brown Color of cured sample 287 Cure temperature, a F, 15 30 Cure time min. Tensile ld./sq. in. 1250 1240 8SO 830 Modul& a t 100 0 , lb./sq. in. 1100 1100 Modulus a t ZOOgp, lb. sq. in 270 310 Ultimate elongation ' ' 76 77 Shore durometer ha;dness (instax It) -60 -60 F. Brittle temperature Flexibility a t 75' F' lb./sq. in. 790 790 110 120 Crescent tear a t 75;'F. 175 175 Blocking temperature, lb./sq. in., " E'. Volume increase % (results on 30-min. cure) Room temu.. 24 hr. in A.S.T.M. ref6.2 erence fuel No. 1 Room temp., 24 hr. in A.S.T.M. ref+51.0 erence fuel No. 2 Room temp., 24 hr. in A.S.T.M. oil
k
CURED POLYVINYL CHWRIDE-PERBUNAN 18 BLENDS 2
3
4
100 50 3 1
100
100 100 3
No. 3
No. 3
24 hr. in Ha0
6 days i n A.Y.T.M. refNo. 1 6 days in A.S.T.M. refNo. 2 6 days in A.S.T.M. oil
e.
Ib./aa. In.
it;
eiongation, % durometer hardness (instant) ing, 6 days a t 260' F. 3q. in. ngation, 70 Shore durometer hardness (instant)
3 1.5 1.5
50
24.1 24.1 48.2 1.155
Brown
287 15 1100 760 880 320 72 -70 490 120 175
80
a
15 780 570 700 350 67 -70
120 175
130 165
500
e Y
30 1100 500 710
360 68
430
23.7 23.7 47.4
1.194
nrolvll
1.107
Brown
287
287
287
15 1290
30 1280
15 1080
30 1350
1370 15
630 340 67 -70 710 110 175
i60
690 350 66 -70 630 130 175
630 310 68 -70 750 120 165
660
650 350
350 63 -70 630 130 175
330 68 -70 760 130 165
64 -70 770 120 155
640 320 88 -70 720 110 175
?SO 320 68
-70
770 110 155
+ 9.7
411.5
+12.2
f13.2
4-11.4
+12.5
562.1
+5* 3
f47.9
+43.3
+47. I
++ 00 .. 22
++ 0.5 0.2
+- 0.6 0.2
f 0.6
+ 0.1
+ 0 5
++ 00 ..45
+f 00 .. 34
-L 0 . 8
+ 0 2
-
"-
-
-
-
--
6.5
- 5.11
+30.6
0.4
3.3
4.7
4.8
5 5
5.8
--
~49.2
+49.6
$50.0
.t60.0
+44.5
+41.2
3-37.0
-
-
--
-
- 3.4
-
-
-
0.6 3.1
1.7 3.8
1.4 4.2
2.6 3.7
-
3.8
3.1 3.8
+ 0.2
3.6 3.8
-
~- 2 . 9
-
3.9
1730 80 69
1490 70 76
1460 110 69
1530 90 68
1230 120 72
1340 130 73
1270 120 78
1300 110 79
1670 60 86
1690 70 82
1720 60 83
1650 70 81
840 20 83
1680 60 81
1720 1-0 83
1630 60 85
2080 0 83
1950
2090 0 89
2160 0 82
1800 0
2120 0 90
1020 0
1450 0 89
2180
2190
91
2230 0 85
2340 0 87
2190 0 84
2340 0
2350
91
2400 0
0
85
88
Ql
0
0
FIGURE 7
2
STOCK T Y P E - vYNW 100,STEARIC ACID 3. LITHARGE 1.5, DIOCTYL P H T H A L A T E 5 0 , PEREUNAN,VARIED. SULFUR 2 PARTS PER 100 PARTS pERBUNAN,BENZOTHI.ULDlSULFlOE
-
V O L U M E INCREASE IN P E R B U N A N - V Y N W
= p
70
-
x
6
-
PERWNAN 26NS 9 0
BLENDS
C U R E D 3 0 ' AT 2 8 7 'F
u' c n
STOCK T Y P E - V Y N W 100, STEARIC ACID 3, LITHARGE 1.5, DIOCTYL P H T H A L A T E 50, PERBUNAN VARIED, S U L F E R A N D EENZOTHI A Z Y L D I S U L F I D E 2 P A R T S P E R 100 P A R T S OF PERBUNAN RESPECTIVE LY
PERBUNAN I 8
9
20
X
Y
e-
0
89
88
-
PERBUNAN 26 NS 90 PERBUNAN 3 5 1 5 90
t
/
U
LL W
PERBUNAN 3 5 N S 9 0
10 W
0 OF
w
3 2
g o PER CENT PERBUNAN IN COMPOUND
89
Effect of % Acrylonitrile on Physical Propexties of Cured Resins Blends. In the experimental work twenty blends were formulated and t)he results are given in Tables I11 t o V, inclusive. Once again this study proved that at 287" F. the optimum cure was obtained in about 30 minutes. Some of the refiults in Tables I11 through V were used to obtain the points for the several curves as shown in Figures 1 t o 7, inclusive. Figures 1 and 2 show that the Perbunan26PiS 90- and Perbunan 35NS 90-resin blends give much
ID
CURED 30' AT 2 8 7
1390 30
..
1-58.0
6 flcctcd directly in the properties of the cured blend. For example, and as is k n o n n , the litharge type blends are slow curing in the tetramethyl thiuram diaulfide formulation, and they have a dark color in a sulfur cure. Figure 10. Cured S) tithetic Elastomer-Poly\ iiiyl Itesin Blends In an attempt to form cured blends Dark portinn of ea& sample expoaed to ultraviolet l i g h t at 12.5’ F.; lighter portions at edges of nitll ilnproved color a llun,i,cr u f anmples were cvvered tcrials or compounds were evaluated. I t mas hoped that some of the commercial vinyl stabilizers as well as othrr test produrts might nctiThe zinc oxide activated blend, even a t a concentration of 5 parts, has poor heat aging properties. In contrast to this, the vate the sulfur-benzothiazyl disulfide cure a t a normal rite. Therefore, Baker’a vinyl stabilizer, Srabclnn -1 (9.177 iodium; litharge blend is completely free from tack and not distorted after c
TABLE‘ T’m. EXI’PM\IEST.lL Sr L B I L I Z t R > IU CL RED Compound No. VYNW Steario aoid Benzothiaryl disulfide Sulfur Baker’s vinyl stabilizer (B.V.S.) Stabelon A (Na and B in oompound as well as Ca and P ) Vanstay ( N a and P in compound as well as P b , Si, and B) Barium oxide Sodium borate Attapulgus olay Tin oxide Sodium acetate Zina oxide Diootyl phthalate Perbunan 26 NS 90 Color of oured produot
100
3 100 3
100
3
2 100 3
1 1
1 1
1
...
1
1.5
..* ... ...
...
... ... . . t
b0*
50
Yellow
1.5
... ...
...
... ... ...
4
PtRBUh‘4S
7
8 100 3
1 1
1
3
6 100 3
1
1 1
1 1
...
...
...
...
...
1.5 ... ... ... . .
...
...
1 5
...
26Ss 90-VE”\v BLESDS 100 3
5 100 3
9 100 3
100
1
1 1
1
1
...
...
...
..
...
..,
...
...
...
... ...
...
...
... .. . .
50
b0 .
.,. 50 50
50 ’ 50
Brown
Yellow
Yellow
io *
50
... 50 50
... . I .
50 50
Light yellow Light yellow Light yellow
... ...
... O I * 50
Yellow
10 3
1
...
..,
1
...
...
... ...
50.
1.5 50 50
...
... 1.5 50
Yellow
.
I
.
... ...
Light yellow
Cure time a t 287’ F., min. 15 30 15 30 15 30 15 30 15 30 15 30 15 30 15 30 15 30 15 30 Speoificgravity 1 . 1 8 3 1 188 1.189 1.183 1.185 1.188 1.180 1.181 1.196 1.199 1.199 1 . 2 0 0 1.203 1.200 1.191 1.191 1.192 1.192 1.188 1.188 Tensile,Ib./sq,in. 1420 1820 1870 1880 1780 1880 1670 1910 1740 1890 1830 1710 1510 1690 1190 1280 1790 2050 1720 1770 Modulus a t loo%, Ib./sq. in. 950 1160 1100 1230 670 760 780 820 630 660 840 1070 920 920 630 650 750 730 680 740 Ultimate elongation, 180 330 390 340 380 320 350 160 200 190 180 330 360 290 350 360 370 270 220 150 % Shore durometer 64 57 59 hardness (instant) 60 62 6BR 67 62 62 64 64 62 61 63 62 63 63 59 61 62 Blocking temperat u r e OF. 219 220 220-% 220 220 220 212 212 230 230 220 220 212 212 150 150 230 230 220 220 No Yes Yes Yes Yes Yes No T r a n s i s r e n t produot Yea Yes Yes Yes Yes Yes Yes Yea Yes Yes Yes Yes No “i
INDUSTRIAL AND ENGINEERING CHEMISTRY
408
TABLE Ix.
PERBUNAN
35x8 ~ O - ~ A R A KB-115 CUREDBLENDS
Saran B-115 Stearic acid Bensothiaeyl disulfide Sulfur Litharge Perbunan 35NS 90 Paraplex G-25 Specific gravity Cure time at 280' F.. min. T e n d e . lb./sn. in. UitiKiti eion'gation, % Crescent tear a t 75" F., lb./in. Shore durometer hardness (instant) Brittle temperature, F. -Moisture vapor transmissii m General Foods methzd, g. HzO/'100 sq. in./24 hr. a t 110 F. and 95% relative humiditv (0.001-in. film) Burning rate
100 3 1 1 1.5
15 4400 210
460 64
- 30 2.3 None
50 25 1.301 30
4550 240 480 65 30
60 4630
240 480
-
- 66 30
2.5 Sone
Kon8
2.5
5 . 2 1 7 ~boron; 7.78% calcium; 3 54% phosphorus and 51.33:h ash), Vanstay (16.67% sodium, 8.33% phosphorus, 0.0011% lead, and 49.12% ash), barium oxide, sodium borate, Attapulgus Clay E55-44B, tin oxide, zincoxide, and sodium acetate were used. The log of the experimental work is given in Table VIII. The use of some of these materials as vulcanizing aids, hoJever, is apparently neIT. The physical properties as evaluated for tensile and modulus arc better than the same type of uncured blend ( I S ) . For example, the uncured blend of Table VI11 has a tensile of 1140 pounds per square inch, modulus of 330 pounds per square inch a t 100yo elongation, and an ultimate elongation of 340%. Also, the blocking temperature is improved if the Perbunan is cured in the Vinglit,e system. Based on blocking values and tensile tests the result,s indicate that the vinyl stabilizers can be used to activate the cures as well as httapulgus Clay, barium oxide, sodium borate, tin oxide, and sodium acetate. A number of these materials gave light-yellow cured products that are transparent (Figure 9). In this work only tin oxide and zinc oxide formulated nontransparent 6 X 6 x 0.075 inch test pads. One important question is light stability, However, work is underway on this subject and the results obtained in a 100-hour ultraviolet light study are shoim in Figure 10. PERBUNAN 35NS 90-POLYVINY LIDINE CHLORIDE BLENDS
As mentioned earlier, it seemed desirable to evaluate Perbunan 36NS 90 as a plasticizer for other vinyl resins. One of the most popular thermoplastic resins are the polyvinylidine chloride copolymers known as Saran. Some of the present commercial. polymers have softening points from 120" to 140" C. Like Perbunan 35NS 90 these resins are resistant to most. chemicals and aromatic hydrocarbons. It was felt that the plasticization of Saran with Perbunan 35NS 90 would be of int,erest as Saran presents many fabricating problems due to the fact that it has a narrower softening range than most other thermoplastic materials. Saran B-115-Perbunan 35XS 90 blends were made by the procedures given for preparation of samples and test results are shown in Table I X . From these data it may be concluded that the gm-
Vol. 41, No. 2
eral properties of cured Perbunan 35NS 90-Saran blends are low water permeability, low burning rate, good tensile and elongation, and interesting low temperature properties. The laboratory processing observations indicated that the blends could be handled in a factory scale operation. This laboratory is continuing H study relating to compounding and processing of such blends. SUMMARY
1. 1,3-Butadiene-acrylonitriYe copolymers were mill niixoti with benzothiazyl disulfide, sulfur, litharge, and vinyl resins, such as Vinylite, VYNW, and Saran and cured to compounds with good tensile strength, modulus, hardness, solvent resistance, and blocking temperature. 2. Results show that the higher acrylonitrile t,ype copolymers give cured S'inylite-rubber blends with higher tensile strengt,h, higher 10070 modulus, and greater ultimate elongation to break than the low acrylonitrile copolymers, 3. The low temperature properties of t'he cured blonds improve as the acrylonitrile content of the synthetic rubber is reduced. 4. 4 n effective c u ~ ae t 287" F. is obtained in 15 to 30 minutes by using 2 part,s of accelerator and 2 parts of sulfur per hundred parts of 1,3-butadiene-acrg.lonitriletype copolymer-Vinylite blends. Added amounts of sulfur, and accelerator did not improve the properties or decrease the cure time a t 287 ' F. 5 . Some of the cured blends studied are tack-free at tcmpcratures as high as 230 F. 6 . Some stabilizers for vinyls tested as well as sodium acetate can be used to activate sulfur cures in 1,3-butadiene-acrylonitrilc copolymer-Vinylite blends t o formulate light-colored transparent, products. ACKKO'3T'LEDGIMENT
The assistance of T. C. Edwards, B. M. Vanderbilt, vi'. J. Sparks, and E. N. Cunningham, during the course of this work, is greatly appreciated. LITERATURE CITED
(1) Advance Solvents and Chemical Corp., "Perbunan" (1938). (2) Badurn, Ernst, U. S. Patent 2,297,194 (Sept. 29, 1942). (3) Henderson, D. E., U.S. Patont 2,330,353 (8ept. 28, 1943). (4) I. G. Farbenindustrie, Brit. Patent 313,569 (June 14, 1928). ( 5 ) Kenney, R. P., M o d e r n Plastics, 24, No. 1, 106-7 (1946). (6) Moulton, M &S., Ibid., 24, No. 2, 117-20 (1946). (7) Nowak, P., and Hofmeier, H., Kunstofe, 27, No. 7, 184-8 (1937). (8) Pittenger, J. E., and Cohan, G. F., Rubber Age, 61, No. 5, 563-6 (1947). (9) Saeger, C. M,, Jr., U.S. Patent 1,889,905(Dee. 6, 1933). (10) Thompson, 0. A., E. 5 . Patent 1,931,309 (Oct. 17, 1933). (11) Winkelman, H. A., I n d i a Rubber W o r l d , 113, No. 6 , 799-804 (1946). (12) Wolfe, J. E., U. S.Patent 2,095,113 (Oct. 6, 1937). Newberg, R. G., and Howlet,t,,R. M., 1x1).EXC. (13) Young, D. W., CHEM.,39, 1446 (1947). RECEIVEDOctober 2, 1947.
Presented before the Division of Rubber Chemistry a t the 112th Meeting of the A x E R I c A x CHEMICAL SOCIETY.Piew York, N. Y .
