TECHNOLOGY to about 80° C , while good reversibility of shrinkage is not observed until this approximate value is reached. T h e leather prepared with Epon 5 6 2 has a high degree of hydrothermal stability and, even after repeated shrinkage, r e tains its leather properties. I t seems likely, he says, that exceptionally stable cross linkages are introduced by this epoxy compound. C h r o m e Tanning. As part of a continuing search for fundamental information on leather and leather treatments, E d w a r d S. Naidus and c o workers of United Shoe Machinery have been investigating the chrome tanning process. T h e basic protein of leather, says Naidus, is collagen, which is found in convenient form i n kangaroo-tail tendon ( K T T ) . This material can be converted into a rubberlike substance by short exposure t o boiling water. Chrome tanning can b e carried o u t Left to right: E. B. Thorstensen, president-elect of American Leather Chemists Asso- on K T T by conventional means a n d ciation; Edwin S. Flinn, president of ALCA; Fred O'Flaherty, secretary-treasurer has the same effect on the final collagen-rubber as has cross linking or vulcanization on ordinary rubber. T h e number of cross links introduced by chrome tannage, says Naidus, i s closely related to the effect of p H on the ionTo m e e t increasing competition from plastics, ization of collagen carboxyl groups a n d leather producers must concentrate on research on t h e chrome complex composition. The process of chrome tanning involves Tanning with Epoxies. Tanning two principal mechanisms: cross linking SWAMPSCOTT, MASS.-In years past leather manufacture has been a studies with epoxy resins were de- of protein chains b y bifunctional c a t vigorous industry. Today, the leather scribed by E. M . Filachione of the De- ionic chrome complexes, and nonspeindustry, in comparison with others partment of Agriculture's Eastern Uti- cific binding of polyfunctional chrome that also can relate their economic lization Research Branch. The 1,2- complexes. growth with population increases, is in epoxides, he says, are capable of easy Analysis of the temperature-dependan unenviable and relatively static po- interaction with proteins, including col- ent behavior of t h e coUagen-rubber sition. T h e pressure of competition lagen, under mild conditions. Treat- network, both tanned and untanned, from plastics and the increasing diffi- ment of cowhide and calfskin with has led to a n e w structural hypothesis, culty in obtaining suitable raw stock, epoxides, such as epichlorohydrin, says Naidus. It is now believed t h a t such as kidskin, have m a d e it all-im- vinyl cyclohexene dioxide, butadiene hydrothermally shrunken collagen is a portant for leaders in the leather field monoxide, and butadiene dioxide, gives network stabilized b y crystallites acting to take a careful look into the future. products with leather characteristics. as giant crosslinks between amorphous This observation was made by Ed- In some cases, the shrinkage tempera- polypeptide chains. ture of the treated material is elevated Resin Emulsions. Water finishes for win S. Flinn, president of the American Leather Chemists Association at its to about 80° C. In general, a n in- leather are complex organic-inorganic 51st annual meeting. Knowledge in crease in the shrinkage temperature in- systems containing mixtures of natural and synthetic waxes, gums, proteins, chemistry and other sciences, he de- dicates that tanning has occurred. clares, should be brought to bear on Preliminary investigations have been pigments, dyes, alkalies, preservatives, the problems of the leather industry. carried out on the treatment of cow- and synthetic resin emulsions, says T h e need for basic chemical research hide and calfskin collagen with an Harold Naidus of Stahl Finish. T h e in this field is obvious. Not only should epoxy resin, Epon 562. This resin scientific compounding of these ingrethis research improve the understand- reacts under mild conditions a n d in dients has resulted in the high quality ing of existing leather processes but aqueous suspension to produce a tan- finishes manufactured today. should also permit the discovery of A m o n g the newer raw materials for ning action. This action is accomnew pr' messes. As an example of a panied by an elevation in the shrink- the finish manufacturer are the synvaluable research contribution, Flinn age temperature and by the unusual thetic resin emulsions. Because they cites the development of the solvent property of reversible shrinkage, simi- permit t h e formulation of superior fintannage process, first suggested in Ger- lar in these respects to formaldehyde ishes for all types of leather, these many in 1912, investigated further at tanning. Little if any reaction or tan- emulsions have won considerable acthe Tanners Council Research Labora- ning effect is observed at pH below ceptance. tory in 1930, and now being carefully F o r the leather finish industry, emulabout 6, says Filachione. examined in pilot plant operation for Tanning is completed within o n e to sion polymerization offers many a d vegetable, mineral, and synthetic tan- 6 days, depending on the conditions. vantages, says Naidus. The product nages. The shrinkage temperature is elevated is obtained directly in the form in
Leather at the Crossroads
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ENGINEERING
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FAMOUS
MONTAUK
POINT LIGHTHOUSE,
completed
LIGHTHOUSES
O F AMERICA
in 1797, was one of
the first to be constructed by the Federal Government following organization of the Lighthouse Service in 1789, Standing on a high headland of rocks and sand dunes, it marks the southern entrance to Block Island Sound as well as the eastern extremity of Long Island— an area of great oZanger to ships because of violent storms and the prevalence of fog.
S a f e p a s s a g e t h r o u g h m a n y channels of production has been provided to thousands of users of electrochemicals by the skillful cooperation of Niagara Alkali Company. Niagara i s a pioneer in the development, production and application of these important chemicals: Nialk® Liquid Chlorine, Nialk Caustic Potash, Nialk Carbonate of Potash, Nialk Paradichlorobenzene, Nialk Caustic Soda, Nialk TRICHLORethylene, Niagathal® (Tetrachloro Phthalic Anhydride) •
NIAGARA ALKALI COMPANY 60 East 42nd Street, New York 17, N. Y.
TECHNOLOGY. which it is to b e used—that is, as a finely divided solid polymer dispersed in water. T h e product is nonflammable a n d a high solids content can be obtained at low viscosities- Furthermore, t h e highest molecular weight polymers are produced with great strength, toughness, a n d resilience. The emulsion polymerization method is also t h e most complex, requiring a careful balance of ingredients for optimum results. Typical ingredients include monomers, water, emulsifiers, water-soluble initiators, accelerators, protective colloids, chain transfer agents, a n d such additional materials as sequestering agents, salts, solvents, and plasticizers. T h e proper selection of these ingredients requires an extensive background in polymer chemistry as well as a thorough appreciation of the industry being served.
Publication Research. M u c h has been said in recent years about the need for increased research on n e w and improved products. Very little, however, xias L>cen sai*u auout t u e urgent need for research on improved methods of communicating the results of science to the readers of technical publications, says Walter J. Murphy, editor of CHEMICAL
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who was the featured b a n q u e t speaker. With the ever-mounting volume of technical literature, new a n d more efficient methods of transmitting scientific findings must b e developed. Present techniques of publication should be carefully reevaluated, not only by the editors of technical journals but also by the contributors of scientific articles and by their readers, says Murphy.
Public Health a n d Air Pollution Federal funds now a n tap let U . S. Public Health Service study how air pollutants affect human health D E T R O I T - F o r the first time, federal funds are available for air pollution research. During the present fiscal year, the U. S. Public Health Service has been authorized to perform studies on the effects of contaminants on h u m a n health. T h e Division of Special H e a l t h Services is engaged in research on the epidimiology, physiology, toxicology, a n d psychology of air pollution. Working with the health services, t h e Division of Sanitary Engineering Services has been directed to perform studies on the physical a n d chemical measurement, identification, and tracing of pollutants. Additionally, this division will investigate the chemical interaction of air pollutants a n d develop methods for controlling or preventing the introduction of contaminants into the atmosphere. The agency also will provide technical guidance and consultation to state and municipal groups in establishing and operating control programs. This governmental role w a s outlined by A. C. Stern, chief of the Air Pollution Control Program of USPHS, at t h e Air Pollution Control Association's 48th annual meeting in the Motor Capital. A registration of almost 8 0 0 experts, representing industry, trade associations, educational institutions, and local, state, and federal groups reported on smoke abatement, air pollution measurements, odor control, and n e w developments in equipment. Organic Pollutants. 2496
ter is so large a proportion of atmospheric pollution that it may not b e ignored, especially in view of t h e known capability of some of these substances to induce pathology in animals and man through prolonged contact. Reporting o n the characteristics and distribution of organic substances in the air of over 3 0 American, Alaskan, and
one English city, L. A. Chambers, also of USPHS, says t h a t the average acetone-soluble fraction of organic particulate matter for the various cities ranches between 10 and 3 0 % . Samples were taken at least once a week, consisting of the total particulate matter removed from about 2000 square meters of air during a 24 hour period. Damage t o V e g e t a t i o n . T h e toxicity of sulfur dioxide, hydrogen fluoride, or other volatile fluorine compounds, and "smog gases" of t h e type found in the Los Angeles area, varies considerably, according to M. Katz of Defense Research Chemical Laboratories in O t t a w a . Sulfur dioxide is readily absorbed by plants but is not a systemic poison. T h e gas is oxidized to sulfate in t h e plant at a b o u t t h e same rate as it is absorbed. Sulfate accumulation is not injurious to leaves until it exceeds t h e threshold value. Gaseous fluorine compounds are more toxic to many species of vegetation than equivalent concentrations of sulfur dioxide. T h e greatest accumulation usually occurs at the tips or margins of the leaves. T h e injurious effects of these air pollutions cause plasmolysis of the affected tissue, a n d inhibition of photosynthesis or degradation of chlorophyll. Radiological W a s t e s . Since radioactivity cannot b e destroyed b y any process except the natural decay of the various species, t h e problem of waste disposal is overshadowed b y the
The 100 cu. ft. of waste per day incinerator, designed and built at Argonne, is the first full-scale unit to be installed as a production unit for the combustion of radioactive wastes
Organic matCHEMICAL
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