I
C. A. URANECK and R. J. SONNENFELD Phillips Petroleum Co., Bartlesville, Okla.
Approaches to
olymer Compoundin
When copolymers of butadiene with vinylpyridine and with acrylic acid interact, the resulting polymer properties differ considerably from the mean of individual copolymers. Such mixtures suggest a new compounding variable
B Y
P R E P A R i S G mixtures of two copolymers having functional groups which interact, orientation and crystallinity not otherwise attainable might be introduced. To study this process, separate copolymers of butadiene with acrylic acid and with 2-methyl-5-vinylpyridine (MVP) were selected because their interaction is simple-Le., between an acid and a base. S o significant study of mixtures of the two copolymers selected has been found in the literature. Recent reviews cite references to several studies on Dolvmer mixtures (8, 75), and several
Table V.
%
80/20
70/30 50/50
b
Monomer ratios of the individual copolymers
b b b
Stoichiometry of functional groups in mixtures Method of mixing the latices or solutions Treatment of the films
These Typical Latex Mixtures W e r e Stable for Several Months
Butadiene-Acrylic Acid Copolymer Latex Bd/AA Solids, PH
90/10
Films formed from mixtures of latices or solutions of the copolymers showed that stress-strain properties were significantly influenced b y
23.2 24.1 32.2 20.8
3.5 4.0 4.9 5.8
Butadiene-MVP Copolymer Latex Bd/MVP Solids, PH
%
90/10 80/20 70/30 60/40
to Recipe A of Table I except that the monomer ratio was varied. Ammonium hydroxide was used after stripping to adjust the p H of the acrylic acid copolymer, but no adjustment, other than stripping, was used on the M V P copolymer latex. Mixtures of the latices with the monomer ratios of 70 to 30 or higher could be made without adjustment of p H if the unreacted monomers were removed by exhaustive stripping. These mixtures were generally sufficiently stable for preparation of films, but long storage stability was not always predictable. Some films were prepared from latices containing monomer charges of 90 to 10> 80 to 20, and 70 to 30 after exhaustive stripping of the unreacted monomers.
16.8
17.5 32.8 10.7
7.9 8.0 8.3 8.4
coagulum After Mixing, 7 0
3 6 1 0
Films from Solutions. Tensile properties of films made from mixtures of solutions of the acid and the amine copolymers were greatly influenced by the method of bringing the polymer solutions together. For example, three methods tried with inert solvents were direct mixing of solutions, layering the second solution onto the first solution, and pouring the second solution onto the semidry film from the first solution. The tensile strengths of film prepared by these methods from equal amounts of 50 to 50 monomer ratio copolymers ranged from 350 to 2100 p.s.i. The films with the lowest tensile strength were rough and heterogeneous; whereas the higher tensile strengths were associated with smooth, uniform
ratio copolymers were prepared i n pyridine and mixed so that stoichiometric amounts of functional groups were present. In the first series, after excess pyridine was allowed to evaporate at room temperature, the films were placed in a forced draft oven; in the second series, final solvent removal was accomplished under reduced pressure (Table VII). The high-tensile strength film from the second series was still readily soluble in pyridine. Prolonged heat treatment or higher temperatures gave films thar; were only partially soluble in solvents. Infrared a n d X-Ray Examination of Films. Films of the two copolymers and of a mixture of the copolymers were prepared by evaporating pyridine from
Table VII. Vacuum Oven Treatment Was Better for Solvent Removal Films
Tensile Strength,
Elongation,
P.S.I.
%
Forced Draft Oven Treatmentn Bd-AA Bd-MVP 5 0 / 5 0 Bd-AA/Bd-MVP
200 0 3200
Vacuum Oven Treatmentb
610
...
460
Table II. Typical Tread and Carcass formulations for Blends of Acid and Amine Copolymers
Table 111. Below 60 to 40 Monomer Ratio, Benzene W a s Needed to Increase the Acrylic Acid Content
Vulcanization temperature = 307' F. Ingredient Elastomer Carbon black Zinc oxide Sulfur Stearic acid Flexamine Santocure Circo-Para
Approximately 607, conversion
Parts
Monomer Ratio Butadiene/Acrylic Acida
100 30 or 50 1.0 1.75 1.0 1.0 0.6-1.0 5.0
Combined Acrylic Acid, %
90/10 80/20 75/25 70/30 60/40 50/50 5 0 / 5 0 (benzene) a
8 19 24 28 34 34 40
Recipes approximately as given in Table
I. Considerable difficulty has been experienced in obtaining reproducible results when copolymerizing dienes with various acid monomers. ( 8 ) . However, in the work here, recipes for butadieneacrylic acid copolymers gave satisfactory results. Also, butadiene-MVP copolymers were easily prepared ; however, for mixtures with acidic latices, emulsifiers of strong organic acids (Table I) were needed. Polymerizations were stopped with di-tert-butylhydroquinone, polymers were protected with phenyl-P-naphthylamine antioxidant, and latices were coagulated with alcohol. All rubber crumb was dried in a n air oven a t 60" C. Preparation of Films from Latices a n d Solutions. Coating the surface of glass containers with carboxymethyl cellulose by evaporating a 1.Oy0aqueous solution greatly facilitated removal of dry films from mixtures of acid-amine elastomer solutions. Films prepared from mixtures of latices, however, were easily removed from glass surfaces. After evaporation of solvent or water under one set of conditions, the films were frequently treated under another set of conditions before testing. Infrared a n d X-Ray Examination of Films. Films of mixtures of the copolymers for optical examination were prepared by evaporating solvents from 2.570 solution of the polymer directly onto potassium bromide blanks. Preparation of the solutions is described in the section on films. Films of mixtures of copolymers were examined by x-ray using a procedure previously reported (6). Compounding Development. Most work on copolymers for tread stocks involved type and amount of metal oxide activation and stearic acid used in the blends. Lithium, titanium, magnesium, lead, and zinc oxides, as well as several organic compounds of some of these metals, were examined briefly. Lead and zinc oxides seemed the most promiiing, and the latter was used in the results reported here. Despite the large amount of carboxylic acid groups in the copolymers containing acrylic acid
units, stearic acid was necessary for the best balance of properties for tread-type vulcanizates (Table 11). Ingredients were mixed on a 6-inch roll mill by a standard procedure. Considerable difficulty was caused by adhesion of the mill stock to the rolls with polymers or blends containing high amounts of acrylic acid, but to avoid contamination, no special releasing agents were used. Although mixtures were vulcanized between sheets of aluminum foil, removal from molds or peeling of foil sometimes resulted in damage to test samples.
Results Polymerization. The same recipe could not be used to prepare a series of butadiene-acrylic acid copolymers that varied greatly in monomer ratio (Table I). When the butadiene-acrylic acid ratio was lower than 60 to 40 an inert diluent such as benzene was employed to obtain a higher bound-acrylic acid content (Table 111).
Table
IV.
Presence of an inert diluent such as benzene increases the amount of acrylic acid in the hydrocarbon phase. This change in distribution is the reason for the increase in combined acrylic acid a t the low butadiene-acrylic acid charge ratios. The effect of inert diluents on composition of copolymers prepared in an emulsion system has been previously recognized ( 74). Distribution of the hydroperoxide between the aqueous and hydrocarbon phases was the reason for increasing the molecular weight of the hydroperoxide as the amount of acrylic acid was increased in the system. The value of this change in hydroperoxides can be demonstrated in a simple recipe in which the acrylic acid is replaced with acetic acid and the aromatic substitution of the hydroperoxide is increased. This effect on the rate of polymerization of butadiene is shown in Table IV. The significance of distribution of the hydroperoxide between the phases in an emulsion system was emphasized in a previous report (73) on hydroperoxides of a homologous series. Films from Latices. Films can be readily formed from mixtures of the acid and the amine copolymer latices by evaporation of the water if several precautions are obFerved. The emulsifier for preparation of the latices should be a sulfate or sulfonate type, the unreacted monomers should be well stripped from the latices, and the p H of either latex sometimes needs to be adjusted with a weak volatile acid or a base so that immediate precipitation of polymer does not occur. This sequence is the most practical way of readying the latices for mixing. Typical examples of latices that formed stable mixtures are listed in Table V. The acrylic acid copolymers were prepared by recipes given in Table I, and the amine polymers were prepared by a recipe similar
Increasing the Molecular Weight and Aromatic Substitution of the Hydroperoxide Improved the Butadiene Polymerization Rate"
/c
xD
C-OOH
R
Hydroperoxide Diox D Diox 7 Diox 8 C1-Diox D Diox 15
X and/or R Propyl tert-butyl sec-amyl Chloro, propyl n-dodecyl
\C
Charge, Part 0.107 0.115 0.128 0.127 0.165
Conversion, yo 2 hr. 6 hr. 34 49 56 59 72
37 75 69 87 85
a Recipe similar t o Recipe E, Table I, except that acrylic acid was replaced with acetic acid; polymerization temperature = 5' C.
VOL. 52, NO. 9
SEPTEMBER 1960
791
~
~~
~~
~
~~
~
ratio copolymers were prepared i n pyridine and mixed so that stoichiometric amounts of functional groups were Butadiene-Acrylic Acid present. I n the first series, after excess Copolymer Latex Butadiene-MVP Copolymer Latex coagulum pyridine was allowed to evaporate a t Bd/AA Solids, PH Bd/MVP Solids, PH After room temperature, the films were placed Mixing, % % 7% in a €orced draft oven; in the second 90/10 23.2 3.5 90/10 16.8 7.9 3 series, final solvent removal was ac80/20 24.1 4.0 80/20 17.5 8.0 6 complished under reduced pressure 70/30 4.9 70/30 32.8 8.3 1 32.2 (Table VII). 50/50 20.8 5.8 60/40 10.7 8.4 0 The high-tensile strength film from the second series was still readily soluble in pyridine. Prolonged heat treatment or higher temperatures gave films that to Recipe A of Table I except that the Films from Solutions. Tensile were only partially soluble in solvents. monomer ratio was varied. Ammonium properties of films made from mixtures Infrared a n d X-Ray Examination of hydroxide was used after stripping to of solutions of the acid and the amine Films. Films of the two copolymers adjust the p H of the acrylic acid cocopolymers were greatly influenced by and of a mixture of the copolymers were polymer, but no adjustment, other than the method of bringing the polymer soluprepared by evaporating pyridine from stripping, was used on the M V P cotions together. For example, three methods tried with inert solvents were polymer latex. direct mixing of solutions, layering the Mixtures of the latices with the monomer ratios of 70 to 30 or higher could second solution onto the first solution, Table VII. Vacuum Oven Treatment be made without adjustment of p H if and pouring the second solution onto Was Better for Solvent Removal the unreacted monomers were removed the semidry film from the first soluby exhaustive stripping. These mixtion. The tensile strengths of film Tensile ElonzaStrength, tion, tures were generally sufficiently stable prepared by these methods from equal Films P.S.I. % amounts of 50 to 50 monomer ratio for preparation of films, but long storage copolymers ranged from 350 to 2100 stability was not always predictable. Forced Draft Oven Treatmentn p.s.i. The films with the lowest tensile Some films were prepared from latices Bd-AA 200 610 strength were rough and heterogeneous; containing monomer charges of 90 to 10, 0 Bd-MVP 50/50 Bd-AA/Bd-MVP 3200 460 whereas the higher tensile strengths 80 to 20, and 70 to 30 after exhaustive were associated with smooth, uniform stripping of the unreacted monomers. Vacuum Oven Treatmentb The mixtures were prepared so that films. Bd-AA 240 900 The best method of preparing films equimolar amounts of functional groups Bd-MVP 80 900 from mixtures of solutions of the acid were present. In a fourth combination 50/50 Bd-AA/Bd-MVP 6000 410 and base copolymers was to use a solvent a 50 to 50 butadiene-acrylic acid latex Solvent evaporated at 20' t o 25" C. for which formed loose bonds with the was mixed with a 60 to 40 butadiene123 hours, then heated a t 60' C. for 41 hours in forced draft oven. Solvent functional groups of one of the polymers. MVP latex. Again the quantities were evaporated a t 20' to 25O C. for 15 hours, stoichiometrically adjusted, but amThe acrylic acid polymer could be disheated in a forced draft oven for 8 hours a t solved in an amine solvent, pyridine monium hydroxide was added to the 60° C., and finally in a vacuum oven for 63 for example, and the M V P polymer in an acid latex to p H 7.0. Each blend was hours a t 60' C. inert solvent, such as benzene, or in poured into a Petri dish and water was pyridine. These solutions could be evaporated for 5.5 days at room temmixed without formation of polymer perature. Dumbbells were cut: and precipitates, and films with high tensile the remaining film was heated in a solutions of the polymers on potassium strengths could be obtained. circulating air oven at 60" C. for 22 bromide blanks. A comparison of the Treatment of the films to remove the hours. Some more of the film was infrared spectra showed absorption bands solvent also greatly influenced tensile boiled in water for 1.0 hour and then at 4.05 and 5.25 microns for the mixture strength. This was demonstrated by two dried for 15 hours a t 60" C. No curaof polymers but no evidence of similar series of experiments in which solvent tives or additives had been added. bands for either of the copolymers by removal was accomplished by two difThe tensile strength and elongation themselves. These bands correspond ferent heat treatments. In both series, values for standard dumbbells are to those found for mixtures of tertiary 5y0 solutions of 50 to 50 monomer given in Table VI. amines and acids in nonpolar solvents
Table V.
These Typical Latex Mixtures Were Stable for Several Months
I
...
Table VI.
Film Treatment and Higher Functional Group Levels Enhanced Tensile Strength
Air Dried Tensile &fOnomer Ratios strength, Elongation, Bd/ AA B d/MVP p.s .i . %
.
9o/ro 80/20
70/30 50/50
90/10 80/20
70/30 60/40
100 200 400 100
Heated 22 Hr. a t 60' C. Tensile Elongastrength, tion, p.s.i. %
2000 2000 About 1500 680
...
50a 3250 1450b
2000 2000 1050 700
Boiled in Water, Heated 15 Hr. a t 60' C. Tensile Elongastrength, tion, p.s.i. % 100 100 650 1850
2000 2000 1100 560
Individual copolymers exhibited essentially no tensile strength after this treatment. dividual copolymers had tensile strengths of 100 t o 200 p s i . after this treatment. a
792
INDUSTRIAL AND ENGINEERING CHEMISTRY
In-
and indicate that the tertiary nitrogen has accepted a proton forming an ionpair bond ( 4 ) . There is little evidence for absorption attributable to carboxylate or pyridinium ion absorption bands, 6.35, 6.12, and 6.72 microns. The latter types are formed between pyridine and stronger acids such as a-haloacetic acids (2) in nonpolar solvents. An x-ray examination of the film exhibiting a 6000-p.s.i. tensile strength (Table VII) showed no evidence of orientation or crystallinity when the polymer film was examined at room temperature, a t dry-ice temperature, or when the film was slowly stretched 700Oj,. However, when stretched quickly to about 50070 elongation, a small amount of orienta-
POLYMER COMPOUNDING Cross Linking at High Zinc Oxide Content Could Overcome the Effect of Carboxylic-Amine Group Interaction
Table VIII.
30-min. cure at 3 0 7 ' F.
Mooney Viscosity5 (Compounded MS-11/2)
PbO,
ZnO, Parts
Parts
1.0 3.0
... ... ... ...
... 0.5
50 55 55 63 56 59 59 3gC
...
... ...
3.0
80' F. I'ensile strength, p.s.i.
300% modulus p.s.i.
... ... ...
1420 1615 2875 1760
...
200° F. Tensile, Elongation, Strength, P.S.I. %
840 2060 2615 3475 1740 2230 3030 3620
520
0.5 1.0 3.0
-
455 275 250 260 355 380 370 520
AT, ' F.
Resilience,
%
...
100 1220
55 61 62 59 58 61 63 64
78 71 87 122 86 65 61
...
1780 840 1000 1180 1780
compounded with various metal oxides (9, 7 7, 72, 76). In the development of a vulcanization recipe for mixtures containing acidic elastomers, large amounts of metal oxides would neutralize the carboxylic groups and prevent interaction with the amine group. For similar reasons the stearic acid content of the compound formulation was maintained as low as possible. The need for maintaining a low concentration of metal oxide in vulcanization of the butadiene-acrylic acid elasto-
Table IX.
Bd-AA 95/5 ad-AA 90/10 Bd-AA 80/20 Bd-AA 70/30 Bd-MVP 95/5 Bd-MVP 90/10 Bd-MVP 80/20 ad-MVP 70/30 Bd-S 70/30 S0/50 50/50 S0/50 50/50 S0/50 50/50 50/50 S0/50 S0/50 50/50 50/50 50/50
blend blend blend blend blend blend blend blend blend blend blend blend
... 30 34 39 79 47 54 48
of 95/5 of 90/10 of 80/20 of 70/30 of of of of
Mooney Viscosity Corn300% Raw pounded modulus, ML-4 MS-lf/p psi
52
95/5 90/10 80/20 70/30
of 95/5 of 90/10 of 80/20 of 70/30
... ... ... ...
... ... ... ... ... ... ... ...
Compression Set, %
48 60 66 73 54 56 61 57
31 15 14 17 24 20 13 21
5 1 3 3 4 2 1 28
mer is shown by a series of experiments in which zinc oxide and lead oxide were varied from zero to 3.0 parts. The vulcanization recipe was the same as shown in Table 11, with 50 parts of Philblack 0, 2.0 parts of stearic acid, and 1.0 part Santocure. Limited physical evaluations are presented in Table VIII. The influence of variable amounts of metal oxides on physical properties was very marked. At high zinc oxide contents the effect of the cross linking with zinc oxide might overshadow the attrac-
Intermolecular Action of Functional Groups Affected Physical Properties of Blends
C.
30-rnin. cure at 3 0 7 '
Monomers and Ratios
Shore Hardness
ASTM D 813-57T modified, flexures to 1
Mooney viscosity of raw polymer (95 to 5 butadiene-acrylic acid copolymer) was 55 ML-4. inch break. Control 70 t o 30 butadiene-styrene copolymer; raw polymer ML-4 was 60.
tion was found but no apparent crystallinity. The evidence on the x-ray print was too faint to justify reproduction here. Compounding. Experiments were conducted with mixtures of the copolymers to determine whether evidence of polymer interaction could also be detected in tread and carcass type formulations. Recent studies reported remarkable cross-linking effects when butadiene elastomers containing large amounts of carboxylic acid groups were
Flex Life X lO-a*
51 53 46 54 39 55 39 49 39
... 2260
80' F. Tensile strength, psi.
200° F. Elonga- Tensile Elongation, strength, tion, % p.s.i. AT, %
50 Parts Philblack 0 270 1100 330 890 340 1100 330 2200 475 1190 495 1165 515 1510 490 1910 510 1200
Resilience, a
F.
Shore Hardness
Freeze, Point,b
%
Flex Life X 103
O
c.
175 150 190 245 200 230 270 310 260
89 89 109 100 79 84 77 68 65
62 55 40 17 61 60 62 67 63
1 4 12 101 6 5 13 54 13
63 65 74 82 57 50 57 58 56
- 39 - 41
260 240
67 65 59 47
3
... ...
Blew 93 87 60
- 37 - 57
4 1
31 34 39 50
610 610 1025 1900
1850 2290 3140 3775
30 Parts Philblack 0 520 560 610 50OC 520 1060 435 170OC
215 350 280 430
87 92 85 72
63 60 54 37
5 13 24 39
48 48 58 67
- 36
1450 1500 2285 3775
50 Parts of Philblack 0 2115 380 690 2800 460 670d 3490 415 1610 4775 390 2600
200 180 265 320
76 99 92 84
59 56 48 32
2 5 12 36
59 58 70 78
- 36 - 46 - 26
2340 3660 1365 1190 1440 1825 1625
2175 2500 2725 4035 2835 2810 3475 3990 3615
- 13 0
- 36 - 61 - 53 - 41 - 47
No Black 25 22
... ... 35 32 38 58 48 51 51 68
85
... 100 Slab
375 365 61OC Tore
ASTM D 813-571' modified, flexures to 1-inch break. minute cure.
590 700 650
...
* Freezing
0 0
... ...
point by temperature-retraction procedure.
VOL. 52, NO. 9
2
- 29
...
- 50 - 24 - 8
- 7
20-minute cure.
46-
SEPTEMBER 1960
793
tive forces set u p by the interaction of the carboxylic and the amine groups ( 76). Butadiene-acrylic acid and butadieneMVP copolymers were prepared from monomer ratios of 95 to 5, 90 to 10, 80 to 20, and 70 to 30 at 5' C. to approximately GOY0 conversion and to reasonable Mooney values. These copol:-mers were evaluated alone and in blends in accordance with the compounding formulation given in Table 11. The Santocure level was varied from 0.6 part for the 70 to 30 butadiene-acrylic acid copolymer to 1.0 part for 95 to 5 copolymer. In the formulation of the 50 to 50 blends of the copolymers, the zinc oxide content was 0.5 part instead of the 1.0 part used in the controls. Three levels of carbon black, 0> 30. and 50 parts, were also tested (Table IX). Superimposed on the averaging of values that might be expected for a mixture of two vulcanizable copolymers are effects possibly attributable to zinc oxide-carboxylic groups and to interaction of the acid and amine groups in the t\vo copolymers. In the data of Table I): several trends are evident which can be ascribed to intermolecular action of the functional groups. Values greater than the average for the control are evident in the stressstrain properties of tread stocks (50 parts black) prepared from blends of the 80 to 20 and of the 70 to 30 copolymers. The effect of blends on hysteresis was mixed, but the resilience for the blends was approximately the average for the controls, except that the blend of the 70 to 30 copolymers was lower than the average by 10 units. Similarly, the flex life and Shore hardness of the blends followed the averages of the controls of the 95 to 5 and 90 to 10 copolymers, but a significant change was noted for the 80 to 20 and 70 to 30 copolymer blends. These had freeze points measurably higher than the averages for their controls. The results of the evaluation show greatest deviations from the average of the controls a t the 70 to 30 copolymer level, some deviation at the 80 to 20 level, and faint deviation at the 90 to 10 level.
The 50 to 50 blend of copolymers does not represent the stoichiometric mixture of the functional groups. This combination \vas tested by blending a 90 to 10 butadiene-acqlic acid poljmer and a n 80 to 20 butadiene-MVP copolymer in a formulation similar to the preceding with 30 p.1i.r. (parts per hundred of rubber) of carbon black Selected values of physical properties are given in Table X . In comparison with the series in Table IX at the 30 p.h.r. loading. the data in Table X seem to represent a better balance of physical properties when stoichiometric amounts of functional groups in the blends were approached.
Discussion Monomer ratios of the individual copolymers, stoichiometry of functional groups in mixtures, method of mixing the latices or solutions, and treatment of the films all affected stress-strain properties. Under optimum conditions tensile strengths 30 times greater (as high as 6000 p s i . ) than those for either individual copolymer treated similarily were obtained. The increase in tensile strength could not be explained by cross linking because the films were still completely soluble. Prolonged heating or higher temperatures would cause cross linking, but the cross-linked films did not show enhanced tensile strengthsthe elongation was decreased. Infrared spectra of the films showed positive evidence of the appearance of an ion-pair band characteristic of tertiary amines and acids in nonpolar solvents ( 4 ) . Identification of other bands characteristic of polycarboxylic acids ( 7 ) and of tertiary amines and acids (2, 3, 5) was not attempted because of the complexiry of the absorption graph. An x-ray examination showed no evidence of crystallinity, and only when the film of the copolymer mixture was rapidly stretched was orientation detectable. Finally a marked increase in tensile strength of the films was not found until the monomer ratio of the individual copolymers was 70 to 30 or less. These results support the belief
that the high tensile strengths of the acid-base copolymer mixtures is caused by interaction betxveen the two copolymers to form relatively weak bonds of the ion-pair type. I n tread and carcass vulcanizates of blends of the acid and base copolymers, physical properties differed from the average that might be expected from a mixture of ttvo vulcanizable copolymers. Stress-strain and freeze points showed the greatest differences from the averages of the two individual controls. and deviations in these properties would be expecred if polymer interaction occurred. The physical properties of the vulcanizates by themsclves do not establish evidence for interpolymer reactions. but in conjunction with the films, the enhanced properties found for polymer blends in the vulcanizate also can be ascribed to interaction of functional groups in the t\vo copolymers. These results show that another variable is available in compounding elastomers containing functional groups capable of inter action.
Literature Cited (1) Allen. G., Caldin, E. F., Quart. Reus. ( L o n d o n ) 7, 255 (1953). (2)- Barrow, G. M., ,J. A x . Chem. Soc. 78, 3805 (1955). (3) Zbid., p. 5802. (4) Barrow, G. M., Yerger, E. A., Zbid., 76, 5215 (1954). ( 5 ) Zbid., p. 5211 ; 77, 4474, 6206 (1955). (6) Beu, K. E., Reynolds, W. B., Fryling, C. F.. McMurrv, €3. L.. J . Polymer Sci. 3, 465 (1918). (7) Bovey, F. A,, Kolthoff, I. M., Medalia, A. I., Meehan, E. J., "Emulsion Polyirrization." Chao. 9. Interscience. Sew
(10) Burke, 0. W., Jenner, R. G., Isli'Y > R. E., Stahley, R. E., "I ieinforcement of
GR-S Synthztic Rubber with Vinyl Resin Fillers. Federal Facilities Gorp., Offce of Svnthetic Rubber, CR-35129
ENG.C ~ I E ~ 5T0., 77i (1958). (13) Fryling, C. F., Follett, A . E., J. Polymer Sci. 6, 59 (1951). (14) Fryling, C. F., Follett, A . E. (to ~
Phillips Petroleum Co.), U. S. Patent 2,685,576 (Xug. 3, 1954). (15) Haws, J. R., Rubber Chem. and Technol.
Table X.
Physical Properties Were More Balanced When Nearly Stoichiometric Amounts of Functional Groups Were Blended
90/10 butadiene-acrylic acid copolymer with 8 0 / 2 0 butadiene-MVP copolymer a t 30 p.h.r. black) 30-min. cure at 307' F. M~~~~~ Monomer
Ratio
Bd-AA Bd-MVP 50/50 Blend
90/10 80/20
a
Viscosity, ML-4
50 44
...
Tensile Strength, P.S.I. 80°F. 200° F. 2900 3200 4300
liesilience,
AT,
1000
58
650 1000
44 58
ASTM D 813-57T modified, flexures to 1-inch break.
retraction procedure. ~~~
794
O
INDUSTRIAL AND ENGINEERING CHEMISTRY
Flex
Freezeb
Life
Point,
4
- 45
7 6
- 44
X
I?. 64 77 64
'C.
- 43
Freezing point by temperature-
30, 1387 (1957). (16) Miller, V. A,, Gienger, E. B., Brown, R. R.; Zimmerman, C. A., "Development of Elastomers with Improved Properties in the .4bsence of Carbon
Black Reinforcement," Armed Services Tech. Information Agency Publications AD 92,179 (1955); AD 92,245, A D 121,303 (1956). (17) Uraneck, C. A., Follett, A . E., Kostas, G. J., IND.END. CHEM.47, 1724 (1955).
RECEIVED for review June 5, 1959 ACCEPTED May 16, 1960 Division of Rubber Chemistry, 4CS, Los Angeles, Calif., May 1959.
I
JAMES D. JACKSON,l HAROLD A. SORGENTIt2 GERALD A. WILCOX,* and ROBERT S. BRODKEY The Ohio State University, Columbus 10, Ohio
Nuclear Waste Disposal b y .
..
Fluidized Calcination of Simulated Aluminum-Type Wastes Fluid bed systems can be designed on the basis of known methods for heat balance and heat transfer
THE scale fluid bed unit for calcining aluminum-type fuel wastes FIRST LARGE
from test reactors is being built at Arco, Idaho (7). There, an aluminum nitrate solution, resulting from treating the fuel elements with nitric acid, is sprayed into a heated fluidized bed of aluminum oxide particles. Water and nitrogen oxides are removed, leaving the waste primarily as granular, free-flowing aluminum oxide. The feasibility of the process has been investigated (2, 5), but neither the rate nor the manner in which dehydration and decomposition occur was considered. In the work described here, these factors are investigated with both aluminum nitrate crystals and solutions. A thermogravimetric oven provided kinetic information on the rate of aluminum nitrate dehydration and decomposition in a fixed bed. Above 2OO0C., the chemical reaction is so fast that physical forces controlled the over-all reaction. The fluid bed gave much better conversions than predicted from the fixed bed data in the 300" to
Table 1. Heat of Reaction and Free Energy Are Functions of Temperature(4) [Al(NOa)a.9Hz0 ( s ) .--t A~(NO~)~.GHZO (s)
+
3Hz0 (Q) A H z s s ~=~ +43,310 ~, cal./g.-mole ki.l(N03)3.GHzO ( s ) + 1/z A1203 3NOz a/40z 6HzO (Q) A H 2 8 8 ~ ~=c . 158,990 cal./g.-mole]
+
Temp., O
K.
298
350 400
450 500
+
+
400" C. temperature range; however, the over-all reaction is still physically controlled. Therefore, in designing calciners for aluminum-type nuclear wastes, the following points should be noted : first, that the fluidized bed provides an excellent system for distributing energy rapidly. The supply of energy is critical; consequently, internal as well as external sources of energy may be required. Second, that atomization of liquid feeds is important in preventing agglomeration of unreacted aluminum nitrate.
Preliminary investigations Early workers ( 6 ) reported that the dehydration and decomposition of aluminum nitrate crystals could be broken down into several independent steps. Limited thermodynamic data reported by Kelly ( 4 ) indicate that the reaction proceeds to completion at temperatures above 425' K. (Table I). To study the dehydration and decomposition steps, differential thermal analysis was undertaken. Its value is in the study of reactions that occur upon heating; heat evolved (or absorbed) by the material undergoing reaction is detected. Decomposition by Differential Thermal Analysis (DTA). Samples of hydrated crystalline aluminum nitrate and calcined product were heated side by
side in an electric furnace. The temperature difference between the sample and aluminum oxide was measured (chromel-Alumel thermocouple) and recorded. The DTA data (Figure 1) shows that an endothermic process occurs when crystalline aluminum nitrate, Al(NO3) 3 ' 9Hz0, is heated from 30" to 100°C. This process represents the combined effects of three physical changes: solution of crystalline nitrate in its own water of hydration, evaporation of free moisture, and partial dehydration of the nitrate. Near 100" C., the sample and the reference material slowly begin to equalize, indicating the continuation of an endothermic process, probably the continued dehydration of the nitrate. At about 145" C., a highly endothermic process, marked by the first evolution of nitrogen dioxide, takes place and continues until the temperature reaches 200' C. After this point, the sample and reference material temperatures begin to equalize as the dehydration and decomposition of the nitrate continues a t a slower rate. Decomposition by Thermogravimetric Analysis. Weight-loss data was obtained to study rates of reaction. Two to nine grams of sample were placed in a platinum crucible suspended in an electric furnace by a platinum wire attached to one arm of an analytical
+
Heat of Reaction, Cal./G.-Mole
Free Energy, Cal.
158,990 158,290 157,610 156,250 156,250
47,360 28,030 9,470 - 9,010 - 27,410
1 Present address, Battelle Memorial Institute, Columbus, Ohio Present address, Atlantic Refining Co., Philadelphia, Pa. 3 Present address, 0. M. Scott and Sons, Co., Marysville, Ohio
Designers of Calciners for Aluminum-Type Nuclear Wastes Please Note! The fluidized bed provides an excellent system for distributing energy rapidly. The supply of energy is critical; consequently, internal as well as external sources of energy may be required 0 Atomization of liquid feeds is important in preventing agglomeration of unreacted aluminum nitrate
VOL. 52, NO. 9
SEPTEMBER 1960
795
