I/EC REPORTS & Silicone Helps X-15 Toward Speed Goal Silastic layer in rocket plane windshield beats the heat during hypersonic
flight I F North American's X-15 research rocket airplane ever achieves the hoped for goal of Mach 6—4000 m.p.h.—its unique windshield must take a share of the credit. Accord ing to manufacturer Sierracin Corp., Burbank, Calif., it's the only elec trically heated windshield that in corporates a temperature resistant interlayer—Dow Coming's Silastic Type Κ—to cope with the heat gen erated during hypersonic flight. Conventional interlayers, usually poly(vinyl butyral), bubble and de teriorate at the 300° F.-plus tem peratures that can be reached at these speeds. Silastic Type K, developed by Dow Corning in conjunction with
38 A
INTERPRETS
the Wright Air Development Cen ter, is a soft and somewhat tacky transparent silicone elastomer that comes in sheet form. Sierracin lays it into a glass sandwich, then cures it in a high pressure auto clave. O n heating, the interlayer becomes a tough, optically clear material and remains so over a wide temperature range. The fin ished pane consists of two plies of semitempered glass, each only 0.125 inch thick, laminated with a 0.04 inch thick layer of the heat resistant silicone. The process also includes vapor de position and electrical connection of a metallic coating developed and manufactured by Sierracin. Called Sicrracote, this transparent coating permits the windshield to be heated electrically to prevent fogging under certain emergency conditions. The X-15 is being tested in a joint program by the National Aeronautics and Space Administra tion, the Air Force, and the Navy at NASA's Flight Research Center, Edwards Air Force Base, Calif. In a flight on May 12, the rocket plane attained Mach 3.0, a speed of 2196 m.p.h. J. S.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Fishy Problem Conservationists look to chemicals for selective control of fish populations l i s h , in one way or another, are a problem to well over half of our states. It's been estimated that about $1.5 to $2.0 million is spent annually to control troublesome species. A dozen years ago (August, 1948, page 12A) we reported on these pages some very interesting work being done with fish as safety indexes in problems concerning the effect of stream pollution on aquatic life. Much progress has been made in reducing pollution and these harm ful effects. But our story today takes the opposite track—what some people are doing in using chemicals to get rid offish. In the south and southeast, they want to eradicate the gizzard shad which infest good bass waters. In many areas, suckers are a problem. But carp can probably claim the championship of all unwanted fish. Several states are looking at ways to control carp and several, in fact, have practiced carp control. Most of the methods used are mechanical, however, and most conservationists agree that these are impractical for many waters. They are looking instead to chemicals which will selectively poison carp. One of the states—New York— has narrowed its search down to a half dozen com pounds, after screening hundreds. Leading the pack is a substituted ammonium fluorophosphate pre pared by Ozark-Mahoning of Tulsa, Oklahoma. Why are carp a problem? They tend to dominate many of the waters they inhabit. They are bottom feeders which have a nasty habit of
Many ideas and projects—big and little—can influence you, give you ideas for use in your work, and provide useful information for "current awareness." Each month I/EC s field editors and Washington staff select for detailed report and analysis, designed for easy reading, some of the most timely, in research and commercial development, process design, engineering, production, and marketing areas in the chemical process industries. We present also our comments on other interesting happenings of business and professional interest.
The Chemical World Today dirtying u p the water. This kills vegetation by cutting down sunlight reaching the water's depths, making it harder for other fish to find food. As a result, some preferred fish are adversely affected while the carp take over. Fish aren't the only losers, however. Recreation seekers suffer too. T h e dirty water, agitated by carp, is unfit to drink, unpleasant in which to swim, and often unsafe even for boating. These are some of the reasons why the New York State Conservation Department decided to look into chemical control of carp. The project also gets financial help from the Dingell-Johnson Federal Aid fund, which reimburses the state for 7 5 % of the tab. It doesn't look like one, but the "laboratory" for this work is a neat cabin alongside a picturesque brook way u p in the Catskill Mountains near Livingston Manor, N. Y. A nearby spring is important to the work, providing a steady 45° F . water supply the year around. There, two conservation biologists, Howard A. Loeb and William H . Kelly, began screening tests on more than 1800 compounds. Of these, only 150 were lethal to all carp tested, even in large doses (100-700 mg. per kg. carp weight, which is far more than would be used in practice.) Half of these were eliminated because they were too soluble in water, would leach out of the bait before carp could get to it. Others were struck out because they were not lethal enough in low doses, were not palatable, or were not selective enough for carp. Some chlorinated hydrocarbons, for instance, kill carp in parts-per-million when put into baits. "Trouble is, they dissolve out and kill everything else in the lake in parts-per-billion," exclaims Mr. Loeb. Ozark's product, which the lab-
William H. Kelly, conservation biologist with the New York State Conservation Dept., watches as test carp go after poison he has just placed inside tank
oratory calls No. 191, and which the company doesn't wish to identify beyond a substituted fluorophosphate, kills carp 20 hours after it is eaten in 20 to 40 mg. per kg. doses. Reason for the secrecy: No. 191's structure is critical. Change it even slightly and the carp might not touch it. No. 191 isn't entirely selective by itself. It will kill trout, but it can be made selective for carp by properly choosing the bait, says Mr. Loeb. Bottom feeders go for baits less likely to attract other fish. This makes bait research important too. Mr. Loeb and Mr. Kelly are looking at several ways to make bait more attractive to carp. Items: coloring, scented materials, and such unrelated flavorings as tobacco juice and maple sugar. Corn is attractive
•
to carp and Mr. Loeb says they are testing corn which has been impregnated with a solution of 50% No. 191 in acetone. Goal is to improve its effective killing time. Even if the right poison-bait combination is found, there is another hurdle to overcome. That is public opinion. People must be assured that poison bait will not adversely affect fish foods, preferred fish, waterfowl, or people. Poison must not be carried into waters where carp are no problem or are preferred, for despite their nuisance, they are widely sought for their food value. Mr. Loeb estimates that around 50 million pounds of carp are caught annually by commercial fishermen and another 50 to 100 million pounds are snared by sportsmen. E.V.A. VOL. 52, NO. 12
·
DECEMBER 1960
39 A
I/EC
REPORTS
AND
INTERPRETS
Dow's "Complexing Resins" Promise Broad Use Versatile oxazolidinone polymers act as product improvers by modifying properties in wide range of materials
W,HEN is a chemical
combination not a compound? In recent years sequestering agents, chelating agents, and complexing agents have become large-scale commercial products serv ing a variety of industries. Most recent and perhaps most versatile complexing agents to check in are Dow Chemical's new oxazolidinones. Besides a water-soluble polymer, Devlex 130—poly(5-methyl, 3vinyl, oxazolidine-2-one)—which its developers term PVOM, Dow has introduced Devlex A515 (a co polymer containing equal parts, by weight, of P V O M and vinyl ace tate) for complexing in organicsolvent systems. These products can control properties (such as solubility, volatility, stability, tox icity) of substances without adversely affecting their chemical nature. A few examples covered in recent patents, and described by Dow's Wilhelm E. Walles at the Tenth Canadian High Polymer Forum, show PVOM's wide applicability: φ Phenol complexes are odorless and nontoxic but retain full bactericidal activity 0 Beverages are clarified quickly and economically
•
Treated tobacco gives bettertasting smoke, deposits more tars in cigaret filter • PVOM hair-setting formu lations work better than do PVP products • Complexed flavorings and es sences have lower volatility, retain strength longer φ Complexes of aspirin or sac charine lose characteristic un desirable aftertastes The PVOM/phenol complex is a 1 to 1 combination, formed by dissolving the polymer in molten phenol at 120° C. It forms also from water solution—equal volumes of 10% solutions of the two ma terials give a white precipitate which is only 0.4% soluble in H 2 0 . The odorless product is less hygroscopic than phenol itself, and may be use ful as an ingredient in germicidal soaps and solutions. Aromatic hydroxyls generally form the strongest complexes. Aromatic carboxylic and sulfonic acids, mis cellaneous thio compounds, anilines, and halogens—these are among the other good candidates. But sterically hindered phenols, and aliphatics generally, form weaker or less stable combinations unless strong
Dr. Wilhelm E. Walles of Dow Chemical illustrates probable chemical structure of the PVOM-phenol complex. 40 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
activating groups (as in the case of trichloroacetic acid) provide high polarity. Beer is Big in Beverages
In the beverage field, clarification of beer could use 5,000,000 to 8,000,000 pounds of PVOM per year, Walles figures. Frequently beer suffers from chill hazing even when it's clear at room temperatures. Most insoluble pectins and tannins can be removed by conventional filtration techniques. But it's not so easy to filter them out when they are highly dispersed or dissolved. And naturally occurring tannin com plexes—which engender turbidity and hazing, and promote off flavors —are a problem, too. Adding 0.001% to 0 . 1 % P V O M (usually 50 to 80 p.p.m. is adequate) precipitates these impurities and makes them easy to filter out. Walles declares this doesn't affect the flavor of the treated brew but gives it a thicker, creamier, and longer-lasting foam. Dow's U. S. Patent No. 2,873,192 covers this application. Fruit juices respond well, too, to P V O M clarification. In fact, Walles says, the material is so effective that using too much of it actually decolorizes the juice, giving un desirably water-white liquids. Cigarets and Hairsets
Treating tobacco with PVOM modifies its properties favorably. Spraying a water solution of the polymer on the tobacco before or during processing imparts a better taste to cigaret smoke, Walles claims. Also, it causes 20% to 50% more tars to be picked up in the cigaret filter (U. S. Patent No. 2,941,907). This means, he explains, that the smoker inhales fewer irritating com ponents. Aerosol products for hairsetting preparations look interesting, too, for this novel material. A recent patent (U. S. No. 2,948,656) suggests that P V O M may work better than PVP under humid conditions. The patent notes that PVP is hygroscopic and sometimes develops a "mousey" smell (perhaps from acetamide formed by degradation of PVP) not experienced with P V O M . And lab tests show that human hair (Continued on page 42 A)
I/EC
THE ADDED FEATURES
REPORTS
picks up more P V O M than it does PVP. This makes the hair retain curl longer (especially at high humidity) and feel softer. Fixes Flavor, Betters Savor
T h e Sperry Filter Press has its obvious merits. In design, capacity and operating requirements—it's customengineered perfect! In construction, it's built solid—to last! In cost, it's thrifty to own and maintain. But the Sperry Filter Press also has other qualities which manifest themselves only after continual usage. When filtration requirements resulting from increased production, new products, varying batch size, cake washing and others arise, your SPERRY FILTER PRESS can usually be changed with a minimum of expense and down time to meet your requirements. With labor saving SPERRY CLOSING DEVICES and PLATE SHIFTERS complete control is reduced to a one-man operation. Get the full Sperry story without cost or obligation. See your Sperry field m a n or m a i l c o u p o n for free Sperry catalog.
D. R. SPERRY & COMPANY Batavia, Illinois Sales
Representatives
George S. Tarbox 80S Nepperhan Ave.
B. M. Pilhashy 833 Merchants Ex. Bldg.
Yonkers, N. Y.
San Francisco, Cul.
Texas Chemical Eng. Co.
Alldredge & McCabe
4 1 0 1 San Jacinto Houston, Texas
8 4 7 E. 17th Ave. Denver, Colorado
The Gilbert Tramer Co.
1217 Main Ave.
As a fixative, P V O M inhibits volatilization of flavors and essences. This gives longer shelf life to prepared food mixes since, for instance, it retains the vanilla flavor usually lost after several weeks or months in conventional packaging. And it could mean less flavoring would be needed in baked goods to provide a specified level in the finished product. Walles's tests show a PVOM/vanillin complex is only 4 % volatilized after an hour at 27° C , as against a 9 7 % loss for vanillin alone under the same conditions. PVOM retains the scent in opened containers of perfume. For a good example of its value as a flavor modifier, P V O M complexes with aspirin to give it a mellow taste, quite different from— and more palatable than—the normally tart acid flavor; physiological efficacy of the salicylate is not altered. Another case: sodium saccharine stays sweet with PVOM, but loses the bitter aftertaste so often noticeable in aqueous solutions 0 . 1 % or higher in content. Additional applications of PVOM include complexes with fungicides and insecticides to reduce their phytotoxic effects. A fully active iodine complex is more soluble in water than is free iodine but won't burn the skin. Bromine is a complcctant which forms a handy, nonpoisonous water purifier for use in swimming pools. And methyl bromide—a soil-sterilant gas which loses much of its potential effectiveness by excessive vaporization— will complex with PVOM to make a solid powder.
Cleveland, Ohio
Not Hard to Make D . R. SPERRY & C O . Dept. I E C 1 2 / % § f f f f Batavia, Illinois
/
I
^ i s ^ ^ w ^
I S e n d Free S p e r r y C a t a l o g
/
[ ~J H a v e y o u r R e p r e s e n t a t i v e C o n t a c t us Name Company Address. City
State.
/ M
Dow makes P V O M by a straightforward process, explains Walles. (The basic operation is covered in U. S. Patent No. 2,842,523.) First propylene oxide bubbles through molten urea, to give 5-methyl, 2oxazolidinone. This is purified by vacuum treatment. Next, a Reppetype vinylation, using a sodium catalyst, forms V O M monomer. This is purified by distillation.
Circle No. 17 on Readers' Service Card 42 A
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
AND
INTERPRETS
These steps are covered in patents 2,891,058 and 2,905,690. Finally, the monomer, with conventional peroxide or azo catalysts, gives PVOM, as described in patent 2,919,279. The polymer of about 1100 monomer units has a molecular weight of about 140,000. The copolymer product, Devlex A515, is not as strong a complexing agent as P V O M itself. But it is still useful, being much more compatible with organic solvents. Walles finds also that the copolymer forms clear, hard films, only faintly hygroscopic. Besides being so versatile, PVOM has a primary practical advantage. Basic raw-material costs are potentially low—only about 12 cents per pound of product. Large-scale production should peg the eventual price well below present development level. Dow has a score of patents already issued on these "complexing resins," their manufacture, and their applications. And the firm estimates about a hundred more are applied for or pending. D.G.W.
Borohydrides Expand Chemical Plating Improved chemical plating possible at lower temperature using borohydrides as reducing agents C h e m i c a l plating on both metals and nonmetals is taking on new stature, this time through use of borohydrides. These materials, excellent and versatile reducing agents, plate nickel and cobalt best. They work at lower—about 45° C.— temperatures, thus are of special advantage in plating thermoplastics. Steel, copper, ceramics, and glass surfaces are also plated with nickel or cobalt by this borohydride chemical plating process. Historically, chemical plating has involved hypophosphites for most (Continued on page 44 A)
I/EC GRINDING
for
FINI LOW
AND
DEHYDRATION
PARTICLES MAINTENANCE
FLUID HERGY
MILLS
THb Fluid Energy "Jet-OBli/er" ΜιΠ. • n g n e d and built by the pioneers * in fluid energy fine grindiiH does far more than produce fine particles. It " «controls fineness and prodTBHPrality with a narrow distribution range • and simultaneously with grinding can dehydrate, coat particles, blend and ο achieve chemical changes. Jet-O-Mizer Mills are being used all over the world, types of materials in the following industries:
processing
many
• Abrasive * Food * Pigment • Wax • Insecticide · Mineral · Plastic · Metal • Ceramic · Pharmaceutical * Carbon • Chemical "Jet-O-Mizing" produces FINE PARTICLES 14 micron average and above PLUS . . . Narrow Particle Distribution · Dry, or Controlled Moisture Content · Continuous Operation · Uniformity of End Product · Other Operations with Grinding · No Attritional Heat — No Moving Parts · Low Operating Costs · Low Maintenance Send for complete information on Fluid Energy's "Jet-O-Mizer" Mills, "Jet-O-Clone" Dust Collectors, and TESTING AND CUSTOM G R I N D I N G services.
FLUID ENERGY PROCESSING & EQUIPMENT COMPANY Richmond & Norris Streets, Philadelphia 25, Pa. · Phone: Regent 9-7728 (Formerly known as the Wheeler-Stephanoff Mill) Circle No. 27 on Readers' Service Card
44 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
REPORTS
jobs. Platers usually operated the bath near the boiling point (95° C.) for maximum deposition rates. Either acid or alkaline baths were satis factory. Generally chemical plating gives a uniformly thick coating on complex surfaces, its main advantage over electroplating. In using borohydride plating baths, the most critical factor in keep ing them stable is pH, according to Edward A. Sullivan of Metal Hy drides. Unless the pH is kept above 12.0, nickel and other metal salts react vigorously with aqueous solu tions of borohydrides evolving hy drogen. A pH of 12.5 to 13 is better, but chemical stabilizers such as sodium citrate or tartrate are still needed. In the process of plating with boro hydrides worked out by Mr. Sullivan and associates and patented this, year (U. S. Pat. No. 2,942,990), concentrations of metal ion and the borohydride ion are kept very low. If the nickel or cobalt ion concen tration goes above 0.15ΛΓ, a side reaction forms a complex salt such as Ni(NH 3 ) e (BH,) 2 . This material does not interfere with the plating process, but it does tie up both metal and borohydrides that should be used in plating. Concentration of borohydride ion above 0.60;V causes spontaneous decomposition of the solution, Mr. Sullivan told the Elec trochemical Society's 118th meeting held in Houston, Tex. The plating reaction can be started by heating the bath from 40° to 50° C. or by adding a small amount of a noble metal catalyst such as Pd ion to the bath. Heating is satisfactory and less expensive. In practice, two solutions are made up to be combined later for the plating bath. One contains the metal to be plated, alkali to bring the pH to 12.5, and a stabilizer to prevent nickel or cobalt hydroxide from precipitating. The other solu tion contains sodium borohydride. Its pH is also adjusted to 12.5. These solutions are stable for months, but after mixing in suitable proportions for use, they are stable only for a few hours. On nonmetallic surfaces, the plated coatings are continuous, ad herent, and conductive, says Mr. Sullivan. They can be soldered to (Continued on page 46 A)
I/EC
MEASURE FLOW IN LARGE PIPELINES with an SK Bypass
Rotameter
You can measure flow in pipelines 2 inches and over conveniently, economically, and with great accuracy by using an SK Bypass Rotameter. These Rotameters measure bypass flow (not static differential) and fluid rate of flow is read directly for ranges as low as 10% of maximum. They use two orifices—one in the main line and one in the bypass line—to provide a fixed ratio of flow through the bypass line. This bypass flow is directly proportional to main flow and rate of flow measuring accuracy is high. Further, the cost of a Bypass Rotameter is low compared with other types of flow measuring apparatus.
SK Bypass Rotameter arranged for vertical downward flow.
SK Bypass Rotameter arranged for vertical upward flow.
Schutte and KoertingCOMPANY INSTRUMENT
DIVISION
STATE R O A D , C O R N W E L L S HEIGHTS, BUCKS C O U N T Y , PA.
^ Circle No. 47 on Readers' Service Card
46 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
by conventional means, or used as a base for electroplating. The coatings are purer than those obtained when hypophosphites are used. A typical coating will contain less than 1% boron, with practically all the remainder either nickel or cobalt. So far only nickel or cobalt seem to plate successfully by borohydride reduction. Mr. Sullivan and coworkers have tried to plate chromium, copper, silver, tin, zinc, and gold. These metals either plated unsuccessfully or made coatings of doubtful value. At present Metal Hydrides is working on commercializing the process. Many details of handling and preparing the solutions remain to be worked out as do techniques of controlling coating to a given thickness. Then, too, because the bath is dilute in both oxidizing and reducing agents, and because the depleted bath usually contains a precipitate of a metal boride, it is not practical vet to recover or renew the bath. B.F.G.
Catfish Row
SK Bypass Rotameters can be arranged for horizontal flow (see photo above) or for vertical flow up or down (see sketches). For complete details—including sizing data—request Bulletin 18B. We'll send it at once.
2275
REPORTS
C A T F I S H were jumping for joy in the Missouri River just below Kansas City recently. The reason— Columbian Steel Tank Co. had just dumped over 1300 gallons of 190proof ethyl alcohol into the river at that point. The tank company was calibrating a meter for use on missile fuel tank trailers for Redstone Arsenal and two other locations. To be absolutely sure of meter accuracy within 0.1 of 1%, engineers decided to calibrate with the identical formulation the trailers were designed to haul. After calibrating with the alcoholwater mixture, the 1300 gallons were disposed of by dumping in the river (reclamation was economically out of the question). With a Government " T - M a n " standing by to keep things honest, the solution was carefully diluted to prevent fire, explosion, or river contamination, and dumped. The last we heard, a large school of catfish, not subject to Federal tax regulations, was still milling about in the Missouri and enjoying a king-size cocktail.
