an
1 I / E qMaterials of Construction Review
by B. S. Garvey, Jr., Pennsalt Chemicals Corp., King of Prussia, Pa. Domestic rubber industry reflects impact of stereo rubber production and of foreign-produced SBR
THIS
IS NOT a comprehensive review for those engaged in the synthesis and fabrication of elastomers. Rather, it is a selection of developments felt to be of general interest to all chemists and chemical engineers. T h e period covered is from M a y 1, 1960, to M a y 1, 1961. Two nontechnical problems of great technological import are : the validity of the General Tire patent on the use of oil-extended styrene-butadiene rubber (SBR) and the competitive struggle in the trucking industry over the use of collapsible, rubber-fabric tanks i n flat bed trucks. Among raw rubbers, the greatest interest is in the increasing production of stereo rubbers, the production of SBR outside the United States, and the impact of these developments on the domestic SBR industry and the use of natural rubber. By using plies of each, the advantages of both rayon and nylon may be combined in one tire. Interesting uses of rubbers range from oil barges to substitute valves for the human heart.
Genera I ‘The interplay of science and technology with politics, economics, and the law is well illustrated by recent developments in the rubber industry. T h e table shows some figures on production of natural and synthetic rubber. U p until 1959, a t least, total consumption was very close to total production. T h e figures for 1940 are given to illustrate the situation prior to FYorld W a r 11. The figures for 1959 and 1962 illustrate changes taking place in 1960 and 1961. T h e influence of our complete dependence on natural rubber before the war and its influence on the development of the synthetic rubber industry in the United States is a n old story. The attention paid to this achievement has obscured the fact that the production of natural rubber has doubled over the past 20 years, largely as a result of scientific developments on the plantations. T h e consumption of natural rubber remains essentially a t its all time peak. However, in the stereo rubbers we have, for the first time, sufficiently close duplicates of natural r u b b r r for complete replacement.
856
I n the past few years SBR production i n the U.S.A. has exceeded consumption, and the balance has been exported. These exports have now reached a volume of 300,000 tons per year. This figure \vi11 fall drastically as foreign production of SBR increases (ZA). Probably by 1962 there will be a n excess production capacity of well over 400,000 tons-excluding the Soviet Bloc (411). Implicit in all these figures a r e questions of export-import and tariff policies, price, national defense, and even political stability in the Far East. T h e trend in tire compounding could be considerably modified by the outcome of suits filed i n various courts over the validity of the General Tire gi Rubber Co. patent on the use of oil extended rubber in tire treads ( 3 A ) . T h e patent was granted as the result of a decree issued by Judge Holtzoff in the U. S. District Court of the District of Columbia which overruled the U. S. Patent Office Board of Appeals. I t is reported that many people in the rubber industry feel that the patent will not hold u p under the pressure of infringement suits. T h e major tire companies are not taking licenses. Since many millions of dollars in potential royalties are a t stake, a fight to the finish seems assured. Collapsible rubber tanks on flat bed trucks have demonstrated their utility, versatility, and economy. but their use is bogged down by legal questions before the Interstate Commerce Commission. These bags, capable of holding 1000 to 3000 gallons of fluid can be transported full on flat bed trucks. When empty
they can be rolled u p and the truck used for dry cargo. M a n y trucking firms want special rates to take advantage of the resulting economy, but they are opposed by the operators of standard tank cars and tank trucks. T h e definition of “rubber” and “rubber products” tentatively adopted by ASTM may well become involved in many court and tariff decisions (711).
Rubbers Natural Rubbers. T h e commercial production and use of S P (superior processing) rubber have been described (73B). I t is produced by blending vulcanized latex with fresh latex before the preparation of sheet rubber. When blended with natural rubber or various synthetic rubbers, i t greatly improves their processing properties, especially for extrusion. Evidence has been advanced to show that the rubber i n fresh latex contains aldehyde groups along the molecular chains (4OB). T h e hardening of crude rubber i n storage is attributed to the reaction of these groups with ac-methyl or methylene groups in other chains to cause cross linking. T h e hardening can be inhibited by the action of monofunctional amines and promoted by the action of bifunctional amines. Natural rubber latex has been irradiated under conditions suitable for commercial use (27B). T h e resultant latex showed improved storage properties and gave improved latex foam. Dry rubber from thc treated latex had
Rubber Production Rubber. 1000 Lone T o n s Synthetic Rubber U.S.A. Rest of Free World” Year. Natural SBR Stereo Other Total p i 0 ... 40 40 2.5 2.5 1415 0 0 1940” 0 ... 220 250 1380 220 1131 0 195Qh 2068 SO 120 790 2100 1200 230 400 1830 620 1962“ Synthetic rubber plants will be in Argentina, Australia, Brazil, Canada, England, France, Germany, Tlolland, India, Ireland, Italy, and Japan. Most producing companies are subsidiaries, affiliates, or associates of American synthetic rubber producers. Figures do not include countries in the Soviet Bloc. Rubbei Statistical BUZZ., International Rubber Study Group, 5 Lancaster Pl., London, WC 2, May 1961 and bIay 1961. Figures are based on published announcements for plants in production, under construction, or being planned for early construction.
I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY
improved extrusion characteristics. Spectroscopic studies indicate that hevea and balata are 100% 1,4-type polyisoprenes (75B). Diene Rubbers. Both raw and vulcanizate properties of natural rubbers can be duplicated (although apparently by Ziegler catalysis only) if the polymerization is so controlled that the polyisoprcne has a high molecular weight, relatively loose gel, and not over 5% of 3,4-structure (78B). Properties and methods of compounding have been described for poly(cis-butadiene) (42B) and for poly(trans-butadiene) (34B). T h e stereo rubbers were shown to be more like natural rubber in dynamic mechanical properties than are any other rubbers ( 7 2 3 ) . Synthetic rubber can be prepared in sheet form from solutions by floating the solution continuously on a moving stream of hot water (4B). Other process improvements which have been reported cover a n extrusion drier for SBR (28B) and a n improved procedure for wrapping bales of SBR (38B). To a considerable extent, the choice between producing poly(cis4soprene) and poly(cis-butadiene) will depend on the relative costs of butadiene and isoprene. Hence, considerable attention is being devoted to the preparation of isoprene from Cs hydrocarbons (ZB, 71B, 76B, 2023, 27B), from mixtures of Cd and Cs hydrocarbons (47B), and from the reaction product of isobutylene and formaldehyde (7QB). New methods of polymerization include the use of thin films (26B) and of thiourea canal complexes for orientation of the monomers (7B). Nonconlugated dienes have been used in place of conjugated dienes (22B). Aromatic sulfonyl halides have been incorporated into butyl rubber to improve its properties (748). Silicone Rubbers. A description has been published of the process used by General Electric to produce siliconehydrocarbon rubbers (8B). The solvent resistance of silicone rubbers is improved by the inclusion of fluoroalkyl groups (33B), while the inclusion of arylene groups improves resistance to combined radiation and heat (32B). Announcement has been made of liquid silicone rubbers which will cure at room temperature and are suitable for use in casting, spray coating, encapsulating, potting, and caulking (77B). Other silicone rubbers will adhere directly to clean iron (7OB). Polyurethanes. Factors governing the production of polyether polyurethane foams have been discussed (3QB),as has the relationship of isocyanate structure to the properties of the cured polyurethane (6B). Polyurethane elastomers can be prepared by casting, either for uses requiring low durometer hardness (23B) or for general use (3B).
A partially cured polyurethane resin has been developed which can be extruded, injection molded, and transfer molded and which cures to a tough elastomer (37B). I t is adaptable to the mass production of small parts. Polyurethanes made by condensing hexamethylenediamine with mixtures of the bis-chloroformates of ethylene and propylene glycol can be made into elastic filaments (25B). Other Rubbers. T h e properties of various ethylene-propylme copolymers have been discussed (7B), along with methods of compounding and processing. The elastomeric polymers appear to have a wide range of usefulness. A new polymer of this type is reported to be vulcanizable with sulfur (5GB). Copolymers of trifluoronitrosomethane and tetrafluoroethylene give vulcanizable rubbers which are resistant to hydrocarbons, oxidizing agents, ozone, and sunlight and which are nonflammable (29B-37B). Silicone-nitrogen polymers are suggested for exceptional heat resistance (35B), as are the products of solid state condensation of diaminobenzidine and diphenyl isophthalate. Highly aromatic polymers are recommended for radiation resistance (5B). Studies have been reported on lead-siloxane polymers (QB), polydimethylgermanosiloxanes (43B), and the reaction products of alkali metal phosphates and isothiouranium compounds (24B).
Processing and Compounding Vulcanization. T h e heat resistance of thiuram cures requires the presence of ZnO because zinc dimethyl dithiocarbamate is a powerful antioxidant which prevents reversion (7C). The concept that loose chain ends in the vulcanized structure of rubber are flaws which have an adverse effect on vulcan’zate properties (77C, 24C) was supported by the synthesis of polybutadiene with active groups in both ends of the chain (telechelic polymers). Under suitable conditions these active groups can bind the chain ends into the structure, with a resultant improvement in properties (30C). Vulcanization by radiation continues to be of interest (9C, lOC, 77C, 18C, 2QC). I n the vulcanization of fluoro elastomers, double bond formation by dehydrohalogenation is followed by crosslinking reactions a t the double bonds (ZOC, 2GC). Aging a n d Deterioration. Ozone attack on SBR is considered to be initiated by ozone attack on a double bond followed by a free radical chain cleavage (6C). The actual cracking is attributed to a reduction in elongation (72C). Appropriate criteria of cut growth were found to be stored energy rather than elongation (2C). It has been proposed that oxidation may be similar to a free radical copolymerization with oxygen ( 75C).
A series of reports has dealt with radiation damage to elastomers and to the use of antirads (IC, 73C, I C ) . Radiation induces high compression set, which can be reduced by the use of appropriate amines (76C, 25C). Pigments a n d Reinforcement. The effect of combined oxygen on the carbon black surface is more on cure than on reinforcement ( 2 8 2 ) . Studies of heat absorption and entropy change indicate that the rubber hydrocarbon can move around on the surface of a black particle or the black particles can move around in the rubber matrix without desorption. Otherwise, ionic powders should give better reinforcemen t than d o carbon blacks. This “mobile layer adsorption” may be related to free radical phenomena (32C). The free radicals may be formed by shear forces during milling (5C). New, low-structure furnace oil blacks have been shown to combine excellent tread wear with low modulus, low hardness, and quiet, soft ride performance (3C). The varied uses for different grades of carbon blacks have been discussed (8C). Processing. T h e type and amount of gel, which influence product quality, have been shown to depend on the time and temperature of mastication (4C). A new type of internal mixer is designed to grind the rubber between the two rotors rather than between the chamber wall and one rotor (23C). Fluid bed heating has been adapted to the continuous cure of extrusions (27C). Heat transfer is better than with gas. There is less danger than with hot metal or oil, and the tendency of the extrusion to float is eliminated. A method for vulcanizing rubber soles directly to leather shoe uppers has been described (7QC) Compounding. Two methods have been proposed for reducing the surface friction of rubber bearinp, bushings, and seals. I n the first, MoSz is either compounded in the stock or coated on the finished parts (22C). The second uses irradiation of the finished article in a solution of methyl methacrylate to form a graft polymer in the surface (27C). The grafted methacrylate is then hydrolyzed and fluorinated. By blending, as latex, a copolymer of butadiene and acrylic acid with one of butadiene and vinylpyridine, a mixture of copolymers was obtained which gave special combinations of properties (37C). Products. By combining nylon plies with rayon plies in the same tires, the Seiberling Rubber Co. believes that it can take advantage of the good features of both nylon and rayon while minimizing or eliminating their undesirable characteristics (730). T h e Goodyear Tire and Rubber Co. has demonstrated a tire case of translucent polyurethane VOL. 53, NO. 10
OCTOBER 1961
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a n b w d Materials of Construction Review which can be dyed any color and even illuminated from within ( 8 0 ) . Rubber-fabric tanks a r e now on trial in the United States for water transportation of oils, where they may replace barges (301,a n d for underwater storage of hazardous materials and those requiring protection from radiation ( 2 0 ) . Rubber-fabric inflated structures have been adapted to the modular construction of buildings (6D). They are also used between trucks and buildings to protect workers and cargo while loading and unloading trucks (770). Rubber-covered rollers are finding many new uses i n making laminated constructions such as plywood (70D). Improvements in belt materials and construction are leading to increased use of belts as conveyors for all kinds of materials: mail, baggage, food? in process. a n d even people (40). T h e flexibility of rubber IS used LO offset expansion a n d contraction of other materials in pads for railroad rails (701, to replace the nests of rollers used as expansion bearings on simple beam bridges ( I D , 7 0 ) , and for expansion joints in concrete roads (720). Sheets of butyl rubber have been used to waterproof the foundations and underground walls of a 44-story office building ( 9 0 ) . Synthetic latex cornpounds a r e used to prevent soil erosion and to act as a mulch during the germination of grass seed (IOD).After several months, it decomposes and washes away. Various injured or diseased parts of the body can be replaced by silicone rubber parts: tubing for bile ducts, valves for the heart, tendons, and retina supports ( 5 0 ) .
Bibliography General (1A) Am. SOC. Testing Materials, Philadelphia, Pa., ASTM D1566-60T, 1960 Supplement to the ASTM Book of Standards. (2A) Arne, Frances, Chem. Bng. 67, 104 (Sept. 19, 1960). (3A) Pfau, E. S., Swart, G. H., Weinstock, K . V. (to General Tire & Rubber Co.). U. S. Patent 2,964,083 (Dec. 13, 1960): (4A) Seaman, R. G., Rubber World 143, 73 (December 1960). Rubbers (1B) Amberg, L. O., Robinson, A. E.. Div. Rubber Chemistry, 138th Meeting, ACS, New York, September 1960. (2B) Anhorn, V. J., Frech, K. J., Chem Eng. Progr. 57, 43 (May 1961). (3B) Axelrood, S. L., Frisch, K . C.. Rubber Age ( N . Y.)88, 465 (1960). (4B) Beal, C., Bosel, L., Chem Eng. P r o p . 57, 80 (May 1961). (5B) Beears, W. L., Fawcett, K . J., Joint Army, Navy, Air Force Conf., Boston. Mass., October 1960. (6B) Blaich, C. F., Jr., Sampson, A. J., Div. Rubber Chemistry, 138th Meeting, ACS, New York, September 1960.
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(7B) Brown, J. F., Jr., White D. M.: J . A m . Chem. Soc. 82, 5671 (1960). (8B) Chem. Eng. 67, 102 (July 11, 1960). (9B) Delman, A. D., Simms: B. B., others, Joint Army, Navy, Air Force Conf., Boston, Mass., October 1960. (10B) DeSieno, R. P., Rubber World 144, 73 (April 1961). (11B) DiGiacomo, A. A,, Maerker, J. B., Shall, J. W., Chem. Eng. Progr. 57, 35 fMav 1961). 2B) Dingle: A. D., Rubber World 143, 93 (October 1960). 3B) Drake, G. W., “Natural Rubber Research Conf., Kuala Lumpur, Malaya, September 1960,” Natural Rubber Bureau, Washington, D. C. 4B) Esso Research & Engineering Co.; Brit. Patent 842,557 (July 27, 1960). 5B) Fraga, D. W.. J . Polymer Sci. 41, 522 (1959). (I6B) Frech, K. J., Anhorn, V. P., Chem. Eng. Progr. 57, 41 (May 1961). (I 7B) General Electric Co., Technical Data Book S-3,1961. (18B) Gibbs, C. F., Horne, S. E., Jr.; others, Rubber World 144, 69 (April 1961) (19B) Giraud, A. L., Am. Inst. Chem. Engrs., Cleveland, Ohio, May 1961. (20B) Goodyear Tire & Rubber Go.. Brit. Patent 841,351 (July 13, 1960). (21B) Gregson, T. C., Rogers, T. H., others, “Natural Rubber Research Conf., Kuala Lumpur, Malaya, September 1960,” Natural Rubber Bureau, Washington, D. C. (22B) Gresham, Mi. F.: Hunt, Madison (to E. I. du Pont de Nemours & Go.). b. S. Patent 2,933,480 (April 19, 1960): (23B) Heis, H. L., Rubber Age ( N . Y.) 88, 89 (1960). (24B) Imperial Chemical Industries. Ltd.. Ger. Patent 970,559 (Oct. 2, 1958). (25B) Kutz, M. (to E. I. du Pont de Xemours & C o . ) , U. S. Patent 2,929,802 (March 22, 1960). (26B) Lynch, J. F., Germack, J. C., Am. Inst. Chem. Engrs., Cleveland, Ohio. May 1961. (27B) Lynn, R . E., Healy, J. C., Chem. Eng. Progr. 57, 46 (May 1961). (28B) Mathews, D. L., Phelps, H. E., Rubber World 142, 76 (July 1960). (29B) Montermoso, J. C.. Chem. Eng. Progr. 57, 98 (April 1961). (30B) Montermoso, .J. C., Griffis, C. B.: others, Div. Rubber Chemistry, 138th Meeting, .4CS, h-ew York, September 1960. (31B) National Research Development Corp., Brit. Patent 843,795 (Aug. 10. 1960). (32B) Ossefort, Z . , Joint Army, Navy, Air Force Conf., Boston, Mass., October 1960. (33B) Pierce, 0. R., Holbrook, G. W.! others, IND.ENG.CHEM.52, 783 (1960). (34B) Railsback, M. E., Haws, J. R., Wilder, C. R.?Rubber World 142, 67 (May 1960). (35B) Rochow, E. G., Joint Army, Navy, Air Force Conf., Boston, Mass., October 1960. (36B) Rubber Age ( N . Y.) 88, 1005 (1961). (37B) Zbid., 89, 116 (1961). (38B) Rubber World 143, 93 (March 1961). (39B) Scholten, H. G., Schumann, J. G., Tenhoor, R . E., IND.ENG. CHEM.52, 613 (1960). (40B) Sekhar, B. C . , “National Rubber Research Conf., Kuala Lumpur, Malaya, September 1960,” Natural Rubber Bureau, Washington: D. C. (41B) Shell Chemical Co., Australian Patents 57,725/60, 59,568/60. (42B) Smith, W. A., Willis, J. M., Rubber Age ( N . Y.) 87, 815 (1960).
INDUSTRIAL AND ENGINEERING CHEMISTRY
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(43B) Staritskii, I. K., Borisov, S. N., others, J . High Mol. Weight Compds. U.S.S.R. 1, 1502 (1959); J. Polymer Sci. 43, 594 (1960). Processing and Compounding (1C) Bauman, R. G., J . A@l. Sci. 2, 328 (1959).
POlJme7
(2C) Braden, M., Gent, A. N., Zbid., 3, 90 (1960). (3C), Bolt, T. D., Dannenberg, E. M.. Div. Rubber Chemistry, 138th Meeting, ACS, New York, September 1960. (4C) Cariton: C. A., Rubber World 141, 678 (1960). (5C) Ceresa, R. J . , Trans. Inst. Rubber Ind. 36, 45 (1960). (6C) Delman, A. D., Simms, B. B., Ruff, A. E., J . Polymer Sci.45, 415 (1960). (7C) Dogadkin, B. A , , Shershnev, V. A.. Dobramyslova, A. V., J . High Mol. Weight Compds. U.S.S.R. 2, 514 (1960); J . Polymer Sci.46, 560 (1960). (8C) Drogin, I., Rubber World 143, 90 (December 1960). (9C) Evans, M. B., Higgins, G. hl. C . , Turner, D. T., J . Appl. Polymer Sci. 2, 340 (1959). (1OC) Fischer, D. J., Chaffee, R. G., Warrick, E. L.. Rubber Age ( N . Y.)88, 77 (1360). (11C) Fischer, D. J., Flegel, V.: Rubber Age N . I-.)88, 816 (1961). (12C) Grossman. R . F., J . Polymer Sci. 44, 266 (1960). (13C) Harrington, R., Rubber Age ( W . Y.) 82, 1003 (1958). (14C) Ibid., 88, 475 (December 1960). (15‘2) Mapo. F. R., IKD.EKG. CHEM.5 2 , 614 (1960). (16C) Mooney, E. E., Semegan, S. T., Rubber World 143, 75 (1960). (17‘2) Mullins, L.? Thomas, A. G.: J . Polymer Sci. 43, 13 (1960). (18C) Mullins, L.! Turncr, D. T., Ibid., 43, 35 (1960). (19C) Niconchuk, A. W,, Rubber Age fN. Y.)88. 85. 284. 472 (1960): Zbid.. p. 650 1196i). ’ (20C) Paciorek, K. L., Mitchell, L. C., Lenk, C . T., J . Polymer Sci. 45, 405 1‘1960). (2iC) Quantum: Inc., Rubber Age (Ar. Y.) 89, 110 (1961). (22C) Rubber Age ( X . Y.)88, 100 (1960). (23C) Rubber W’orLd 143, 86 (November 1960). (24C) Scanlon, J.: J . Polymer Sci. 43, 501 (1960). (25C) Shelberg, W. E., Gevantman, L. H., Joint Army, Navv, Air Force Conf., Boston, Mass.; ’October 1960. (26C) Smith, J. F., Rubber World 142, 103 (June 1960). (27C) Soden. A. L., Zbid., 143, 102 (March 1961). (28C) Sweitzer, C. W., Burqess, K. A.. Lyon, F.? Ibid., 143, 73 (February 1960). (29C) Turner, D. T., Polymer 1, 27 (1960). (30C) Uranek, C . A , Hsieh, M. L., Buck. 0. G.: J . Polymer Sci. 46, 535 (1960). (31C) Uranek, C. A., Sonnenfeld, R. J., IND.ENG.CHEM. 52, 790 (1960). (32C) Wake, h’.C., Trans. Zn.rt. Rubber Ind. 36, 58 (1960). I
,
Products
(1D) Berridge, P. S. A,, Rubber DeueloFments 13, 117 (1960). (Published by Satural Rubber Bureau: Washington,
+j
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em. Eng. 67, 8 8 (June 13. 1960). 3D) Zbid., p. 61 (June 27, 1960). (4D) d’Adolph, S. V., Rubber World 144, 76 (April 1961).
(5D) Dow Corning Corp., Zbid., 143, 67 (March 1961). (6D) Du Pont, Elastomers Notebook No. 97, P. 736 (December 1960). (7D) Gen’t, A. N., Lindlei, P. B., Mullins, L., “Natural Rubber Research Conf., Kuala Lumpur, Malaya, September 1960,” Natural Rubber Bureau, Washington, D. C. (8D) Goodyear Tire & Rubber Co., IND. END.CHEM.53, 17A (February 1961). (9D) Humble Oil & Refining Co.. Chem. ‘ ELg. 67, 86 (July (10D) Hyler, J. E., 11D) Rubber Age ( N . Y.) 87, 883 (1960). 12D) Rubber World 142, 101 (September 1960). (13D) Seiberling Tire & Rubber Co., Rubber World 144, 81 (April 1961). Books
(1E) Berlant, W. J., Hoffman, A. S., “Block and Graft Polymers,” Reinhold, New York, 1960. (2E) Bostron, S., ed., “Kautschuk Handbuch,” Vol. I, Berliner Union G.m.b.H., Stuttgart, 1959.
(3E) Charlesby, A., “Atomic Radiation and Polymers,” Pergamon Press, New York, 1960. (4E) “Encylupedie Technologique d 1’Industrie du Caouchouc,” Vols. I-IV, S. R. L. Dunod, Paris, 1960. (5E) Lerner, M. E., ed., “Bibliography of Rubber Literature for 1955-56,” Div. of Rubber Chemistry, ACS, 1960. (6E) Houwink, R., Bouman, H.. “Classifications of High Polymers,” Butterworths, London, 1960. (7E Huke, D. W., “Introduction to datura1 and Synthetic Rubbers,” Hutchinson & Co., Ltd., London, 1961. (8E) “International Rubber Directory,” Verlag fur Internationals Wirt-schaftlilerateur G.m.b.H., Zurich, 1960. (9E) Payne, A. R., Scott, J. R., “Engineering Design with Rubber,” Interscience, New York, 1960. (10E) Penn, W. S., “Synthetic Rubber Technology,” Vol. I, Palmerton Publishing Co., New York, 1960. (11E) Tobolsky, A. V., “Properties and Structure of Polymers,” Wiley, New York, 1960. Symposia and Panel Discussions (1F) Rubber Age ( N . Y.) 87, 1038 (1960),
a I N THE WORKS
Joint Army, Navy, Air Force Conf., Boston, Mass., October 1960. (2F) Ibid., 88, 505 (1960), engineering aspects of pneumatic tires, some concepts of tire compounding, tire manufacturing. (3F) Zbid., 88, 505 (1960), bases of SBR production, packaging of SBR, quality control of SBR. (4F) Zbid., 88, 676 (1961), Berlin Congr., German Rubber Society. (5F) Zbid., 88, 829 (1961), Ninth Annual Wire Symposium, U. S. Army Signal Research & Development Laboratory. (6F) Rubber World 143, 43 (January 1961), tires, mechanical rubber products, latex, footwear, soles and heels, insulated wire and cable, reclaimed rubber, physics of rubber. (7F) Zbid., 144, 86 (April 1961), ABC’s of radiation. radiation degradation of elastomers, radiation vulcanization, radiation techniques for analysis and measurement. (8F) Zbid., 144, 89 (April 1961), retreading problems, manufacture of tread rubber. (9F) Zbid., 144, 89 (April 1961), metal oxides in compounding: MgO, ZnO. (10F) Ibid., 144, 111 (April 1961), Kuala Lumpur Conf. on Natural Rubber Research.
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Manuscripts Accepted for Publication in Forthcoming Issues of I / E C
Poisoning in Fixed Beds of Catalysts
R. B. Anderson and A. M. Whitehouse Bureau of Mines, Pittsburgh, Pa. Effect of distribution of a poison on the average activity of a bed is examined for several types of poison concentration gradients
Sulfuric Acid Manufacture
- Optimized Conditions in Contact
A. C. Homme and D. F. Othmer Polytechnic Institute of Brooklyn, Brooklyn,
N. Y.
Production of sulfuric acid from pyrite ore is simulated with an IBM 605. The method of steepest ascent is used to maximize profits
Continuous Solids Feed to Parallel Fluidized Beds
D. S. Koons and B. E. Lauer University of Colorado, Boulder, Colo. Uniform feed of solids is accomplished by dense phase flow through multiple tubes, controlled by orifices. Empirical design equations are given for ground oil shale
Catalytic Deposition and Grafting of Olefin Polymers into Cellulosic Materials
A Rapid Method for Vapor-liquid Equilibrium Data
R. S. Ramalho, F. M. Tiller, W. J. James, and The University of Missouri, Rolla, Mo.
D. W.
Bunch
Apparatus is designed for simple distillation with continuous feed and product removal. Mathematical treatment of the data is given
The Gradient Method in Process Control
D. J.
Bridgeford Tee-Pak, Inc., Chicago, 111.
S. M. Roberts and H. 1. Lyvers T. R. W. Computers Co., Beverly Hills, Calif.
Ion exchange properties of cellulose can be used to bind polymerization catalysts. Location of polymer formation can be controlled, and properties of cellulosic materials can be modified by polymer deposition
This method, which is easily adapted to on-line computer control, can handle nonlinear objective functions with nonlinear restraints. Two methods are illustrated: hemstitching and ride-the-constraint technique
Activation of Uranium Dioxide by Successive Oxidation and Reduction
Hydroreflning Coal Tar Naphthalene
H. Hunter
R. J. Bard, J. P. Bertino, and D. L. Bunker University of California, Los Alamos, N. M.
Gerald Gilbert, R. C. Weil, and R. U. S. Steel Corp., Monroeville, Pa.
Low reactivity UOz can be converted to a very reactive form by this simple procedure, This activation is suggested for controlling reactivity in processing of UOz reactor fuel
Hydrogenolysis over cobalt molybdate catalyst removes impurities containing oxygen, sulfur, and nitrogen. Data show high yields and good catalyst life VOL. 58, NO. 10
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