Stepan's Sulfonation Process Results in Purer Surfactants New continuous process cuts down sulfates and sodium chloride in surfactants and intermediates
NOSE CONE GOES ON. The nose cone fairing is being fitted around the canister containing the 135-ft. diameter balloon. It will go up 950 statute miles
A great deal of research has been done generally on the effects of radiation on polymers during the past decade. But NASA must examine a series of polymers, since most research in this field has been concerned with radiation in nuclear reactorsneutrons mostly. In space, satellites are exposed chiefly to streams of electrons and protons as well as ultraviolet light. Radiation in space is also definitely in a very high vacuum— and some of the literature describing previous work in this field is confusing on this point. To get data on radiation effects, the space vehicle group at Langley is therefore running a great many tests of its own with beams from a linear accelerator and with ultraviolet light. One possibility of coping with ultraviolet radiation is to incorporate a protecting chemical—such as a ferrocene derivative—in the polymer. An entirely different approach is to try to find a good film which would disintegrate altogether under irradiation in space, leaving the windows open. So far, the Langley workers haven't found such a material. Polymethylmethacrylate would disintegrate rapidly enough—but it does not form a very good film, according to Dr. George F. Pezdirtz, who is in charge of polymer research at Langley. Memory Effect. Although their thinking on the subject is still "way out," Dr. Pezdirtz and his associates are studying a polyethylene web that has been irradiated to give it a "memory." The web is irradiated, heated, and then cooled in a folded condition. The cross-linking between polymer molecules tends to fix their positions
relative to each other. The web will remain in its folded position until reheated; then it resumes its original extended condition. It could be possible to make a sphere of aluminumcoated polyethylene grid, which could be expanded in this way once it is placed in orbit. This would be a means of shipping energy into space without the weight of the chemicals now used to expand the balloon. At present, Radiation Applications, Inc., Long Island City, N.Y., is carrying out some work on phases of this problem, using Du Pont's Vexnar extruded polyethylene web. The heat for expanding the web would come from the sun. The NASA group has thought of controlling the effects of the sun. The polyethylene would be coated with a black dye, which would cause it to absorb heat. By selecting a dye of the proper molecular weight, its volatility could be adjusted so that by the time the polyethylene had absorbed enough heat, the dye would have volatilized, exposing an aluminum surface imbedded deeper in the web. The aluminum would reflect the heat rays allowing the satellite to cool down and become rigid. Although an aluminum-plastic laminated sphere can become rigidized by stressing the aluminum beyond its yielding point, NASA is also interested in other possible means of rigidization in space. Hughes Aircraft Co. has recently completed a research contract for NASA investigating foaming and cross-linking polymers and laminates which can be carried into space and rigidized using the UV radiation and heat of the sun.
Stepan Chemical has a continuous sulfonation process capable of turning out high purity surfactants. It uses liquid S 0 3 in a unique, single-pass process that has shorter reaction time than the "dominant bath" process. Materials being made by the new process include dodecylbenzene sulfonic acid, sodium lauryl sulfate, and fatty alcohol ether sulfates. In still another application, the continuous process gives nonionic sulfates that can be neutralized with any cation, Stepan director of research Edward A. Knaggs told the American Association of Soap and Glycerine Producers, meeting in New York last week. Materials made by the new process are purer than those made by older processes. Dodecylbenzene sulfonic acid, made by Stepan's sulfonation, has sulfate impurities one sixth of those found in material made by typical batch-type oleum processes. Sodium lauryl sulfate is free from viscosity-increasing sodium chloride from older chlorosulfonic acid processes. Change from these processes also produces better fatty alcohol ether sulfates which have low sulfate content, good color, and superior foaming properties, Mr. Knaggs says. Until now, all nonionic sulfates have been ammonium salts made from sulfamic acid. Stepan's S 0 3 process gives an acid any cation can neutralize. Most continuous sulfonation processes consist of two major loops or "dominant baths." A mixture of oleum and raw material is fed into a reactor loop, then recirculated through a heat exchanger loop system. Many of these processes, though, suffer from major drawbacks, says Mr. Knaggs. They are difficult to control, involve long reaction times. They give highly colored products containing lots of sulfates. Stepan won't talk details until patents have been issued. However, it's known that Stepan can closely control process variables, has licked problems of metering, mixing, heat removal, and product removal. This way reaction time can be kept to a minimum, and high purity products with good color can be obtained, Mr. Knaggs told the meeting. JAN.
2 9, 1 9 6 2
PART
1 C&EN
49
