Vol. 40, No. 11
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
2090
Softness arid the acconipanj irig btickiness arid compact ncss MERCAPTAN AS ~ I O I J I - tended t o increase with increasing quantity of modifier, a tendTABLE IX. EFFECTOF n-TETRADECYL FIER WITH B E X ~ O Y PEROXIDE L AS ChTAI.YSTa ency more pronounced with the tertiary than with the normal Catalyst, Modifier, Solubility mercaptans. With each series of mercaptans the softncss of the Benzoyl n-Tetradeoyl (in Yield, Visoosity Benzene), Peroxide, Mercaptan, copolymer varied inversely with the carbon content of the merNo. Gram Gram % (hr/c) 74 captan. The softening tendency of the modifiers was more 40 1 3.67 94.1 0.02 1 0.04 pronounced when benzoyl peroxide rather than potassium per2 0.04 55.4 2.62 99.2 0.08 2.09 99.2 3 0.04 62.7 0.12 sulfate was used as the catalyst. At the lowest mercaptan levels, 4 0.08 24.4 3.72 98.4 0.02 5 0.08 66.1 3.17 97.1 0.08 however, the products obtained with benzoyl peroxide were hard 73.3 0.12 2.63 99.2 6 0.08 and tough. Increase in percentage of styrene tended to increase 0.06 62.7 3.03 76.8 7 0.12 8 0.12 75.3 2.96 98.7 0.10 hardness and toughness. 0.14 80.6 2.55 99.0 9 0.12 15.0 grams isoprene, 5.0 grams styrene, 40.0 ml. 2.5% soap solution, polymerized 18 hours. Q
those used for the n-dodecyl and n-tetradecyl mercaptans and under the same conditions. However, none of these mercaptans seemed promising. The products prepared with n-decyl mercaptan were practically completely soluble in benzene and had viscosities ranging u p t o 3.33, but the yields were very poor, below 35y0. With the n-hexadecyl and n-octadecyl mercaptans the yields were somen-hat higher, ranging up t o 54%, but the solubilities were generally poor and the viscosities mediocre. TERTIARY MERCAPTAKS.The effect produced by variation in quantity of tert-octyl, tei-t-dodecyl, tert-tetradecyl, and tei-t-hexadecyl mercaptans with different quantities of benzoyl peroxide was investigated. Of these the tert-dodecyl mercaptan gave the best results and several copolymers possessing high solubility and viscosity were obtained in good yield with this mercaptan. Representative data obtained with this mercaptan are given in Table X. At each catalyst level the yield increased with increase in amount of modifier, rapidly at first; then more slowly. Except a t the lowest mercaptan levels the viscosity values were all relatively low and at each catalyst level decreased with increasing mercaptan content. The solubility was high in all cases.
CONCLUSION
Isoprene-styrene copolymers possessing a high degree of solubility in benzene and high inherent viscosity can be prepared in good yield under a variety of conditions with respect t o catalyst and modifier by emulsion polymerization. With potassium persulfate as catalyst best results were obtained with certain levels of the n-dodecyl and tetradccyl mercaptans and of the tertoctyl, dodecyl, tetradecyl, and hexadecyl mercaptans as modifiers. With benzoyl peroxide a3 catalyst best results were obtained iyith the n-tetradccyl mercaptan. ACKNOWLEDGMENTS
The authors wish t o express their appreciation to Barbara E. Hillery for assistance in the polymerization work and in the solubility and viscosity determinations, and t o Dorothy Tvl. Oldroyd for fractionation of the isoprene. LITERATURE CITED
Barron, H., “Modern Synthetic Rubbers,” 2nd ed., pp. 52-66, New York, D. Van Nostrand Co., 1943. Baruch, B. IW., Conant, J. B., and Compton, K. T., “Report oi the Rubber Survey Committee,” p. 68, Sept. 10, 1942. Cragg, L. H., J . CoZloid Sei., 1 ( 3 ) , 2 6 1 (1946); Rubber Chem. Technol., 19, 1092 (1946).
O F tert-DODECYL ?VIERCAPTAN AS TABLEx. EFFECT WITH BENZOYL PEROXIDE AS C.4TALYSTa
No.
Catalyst, Benzoyl Peroxide, Gram 0.02 0.02 0.02 0.04 0.04
Modifier, tert-Dodecyl Mercaptan, Gram 0.02 0.04
Yield,
%
Viscosity (lnvr/c)
;\IODIFIER
Solubility (in Benzene),
%
99.3 2.17 100.0 1.43 98.7 0.83 0.08 99.2 2.12 0.02 99.7 1.33 0.06 1.14 98.8 0.04 0.08 99.5 1.31 0.08 0.04 99. 3 1.19 0.06 0.08 98.0 0.90 0.10 0.0s a 16.0 grams isoprene, 6.0 grams styrene, 40.0 ml. 2.5% soap solution, polymerized 18 hours. 56.1 6 1 .9 65.6 52.7 74.9 76.6 60.2 69.7 74.1
Polymerization products obtained with tert-octyl mercaptan as modifier, and benzoyl peroxide as catalyst, possessed high solubility (above 99.0y0) but were very low in yield (less than 40%) and in viscosity (less than 1.0). tort-Tetradecyl mercaptan also gave polymers with substantially complete solubility but with somewhat better yields (up to 6870) and viscosities (up t o 1.7). Use of terthexadecyl mercaptan gave polymers in substantially the same yield and solubility as did tert-tetradecyl mercaptan b u t with distinctly higher viscosities (up t o 2.83). With all four tertiary mercaptans investigated, a t each level of benzoyl peroxide used, the yield tended to increase with increasing mercaptan content, but the viscosity tended t o decrease. PHYSICAL CHARACTER1STICS
The copolymers obtained varied widely in appearance and in rubberlike characteristics. They ranged from very tough, spongy, dry, and hard at one extreme to weak, compact, sticky, and soft even t o the point of plastic flow, a t the other extreme.
Craig, David (to B. F. Goodrich Co.), U. 5.Patent 2,362,052 (Kov. 7, 1944). Croxton, F. C., IND. ENG.CHEX.,ANAL.ED.,14, 593 (1942). Davis, B. L., Goldblatt, L. A., and Palkin, S.,IND. ENG.CHEM.. 38, 53 (1946).
Flory, P. J., J. Am. Chem. SOC.,65, 372 (1943). Fryling, C. F., IND. ESG.CHEX.,AXAL.ED.,16, 1 (1944). Fuller. C. S.. Bell Telephone Swstem Tech. Publs., Mononraph B1405, 5 , 8 (1946).
Palmer, R. C., IND.ENG.CHEM.,34,
1034 (1942);
35, 1025
(1943).
Rubber Age, 52 (3), 244, 247 (1942). Zeitfuchs, E.R., ’Vatl. Petroleum N e w s , 31, 109 (1941). RECEIVED June 16, 1947. Based upon a paper presented before the Division of Rubber Chemistry and the High Polymer Forum a t the 110th Meeting of the .kMERICAN CHBMICAI, SOCIETY, Chicago, 111.
Corrections The editors regret t h a t the title “Pyrolysis of Hydrocarbons” [IND.ENG. CHEu., 40, 1660 (1948)l incorrectly describes the subject matter of the article appearing thereafter. The review article by Vladimir Haensel and Melvin J. Sterba covers pyrolytic and catalytic decomposition of hydrocarbons. The article as originally submitted contained a n adequate title. The editors apologize for the incorrect title substituted during editing of the review.
....*..
I n the biographical sketch of Stephen I?. Perry [IxD. EKG. CHERI.,40, 1554 (1948)] it is stated t h a t Mr, Perry served on the Aviation Gasoline Advisory Committee. He was not actually a member of this committee or of its Isomerization Subcommittcv, although he was active in the work of the subcommittee.
