bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Permeability of Rubber to Water Vapor
Authors: Van Dalfsen J. W. 
Published: February 2011

Abstract
In connection with a study of various kinds of vulcanized rubber, including rubber films from vulcanized latex and latex films vulcanized in the dry state, it seemed desirable to investigate the packing of the latex particles. To what extent, for example, are these still present or are they coalesced? It is known that the diffusion of water vapor through solid substances may give an indication of the internal structure of matter. With this in mind, a search was made for a simple method to determine the diffusion of water vapor through rubber; high accuracy was not required so much as were simplicity and adaptability to a long series of experiments. Such a procedure was found in the method described by Hoekstra for determining the permeability of varnish films to water vapor. A detailed description of the method is given later in this paper. More accurate methods of determination, applied to rubber, have previously been described by others, but these procedures are less suitable for systematic tests.
Experiments on the Preparation of Transparent Vulcanized Rubbers
Authors: Johnson E. B. , Scott J. R. 
Published: February 2011

Abstract
1. It has been found possible, by the use of combinations of organic accelerators, to prepare accelerated rubbers which contain sufficient zinc oxide for activation but show no trace of pigmentation by the oxide, and are quite as transparent as a mixture containing only rubber and sulfur, and often lighter in color than the latter mixture. These accelerated rubbers have excellent tensile properties. The aging properties vary considerably according to the accelerators used, but in most cases are very good, even if the rubber is over-cured. It is, therefore, possible to make nonblooming rubbers without danger of bad aging. 2. Tests with other activators (zinc carbonate, zinc oleate, and zinc stearate plus magnesium carbonate) showed that these are less effective than zinc oxide, for the vulcanizates obtained had inferior mechanical properties and, in the case of zinc carbonate and oleate, showed a strong tendency to bloom. 3. A combination of accelerators which has been stated to work well without activator was shown to vulcanize very quickly, but to give poor mechanical properties, 4. The tendency of various accelerators to give rubbers, the surfaces of which are easily marked by scratching, presumably owing to efflorescence of accelerator, was noted. 5. The most promising of the mixtures tested for making transparent vulcanized rubbers was one accelerated with diphenylguanidine plus mercapto- benzothiazole, with zinc oxide as activator (mixture F). 6. A mixture is described (mixture K) which gives better aging when vulcanized beyond the optimum tensile properties than when vulcanized short of the optimum cure. 7. Rubbers can be toughened by the use of organic accelerators so as to possess greater resilience and lower permanent set than if toughened by the usual inorganic reinforcing agents. The aging tests described above were all made in the absence of light. For transparent rubber goods which are exposed to light during use, the addition of antioxidants and (or) softeners might be found necessary to give resistance to deterioration by light. In connection with fancy goods, the staining of paper in contact with the rubber may be of importance, and in such cases the choice of accelerators and antioxidants must be made with this in mind. The staining effects of numerous accelerators and antioxidants have already been described. In conclusion, it should be added that the experiments were directed in the first instance towards the production of brown transparent rubbers, for which reason smoked sheet was used. Where a light-colored vulcanizate is required, and especially when it is desired to obtain colored rubbers by adding organic dyes, the use of pale crepe is essential.
Statistical Lengths of Rubberlike Hydrocarbon Molecules
Authors: Wall Frederick T. 
Published: February 2011

Abstract
It has been known for some time that the pure hydrocarbons of balata (or gutta-percha) and natural rubber have the same chemical composition and chemical properties. Both balata and rubber appear to be polymers of isoprene, (C5H8)n, with the same degree of unsaturation. Their physical properties are sufficiently different, however, to make it clear that their structures must differ in some important respect. Since the molecules contain numerous double bonds, it has been suggested that rubber and balata are geometric isomers. Every fourth bond in a rubber or balata molecule is a double bond, so it follows that the possibilities for geometric isomerism are considerable. It was proposed by Meyer and Mark that natural rubber hydrocarbon has a structure for which the molecular chain is cis with respect to all of the double bonds. Balata (or gutta-percha) is then supposed to have a trans-structure throughout, this view having been verified by Fuller and Bunn. It is the purpose of the present paper to consider, from the point of view of recent theories of rubber elasticity, to what extent these structures explain the differences in physical properties. The method to be employed involves calculation of the root mean square lengths of the cis- and trans-structures, which, when compared to their maximum lengths, should give an indication of their extensibilities. In 1932 Eyring treated the problem of the average square length of a hydrocarbon chain. In the present paper a different derivation of Eyring's equation is given (for illustrative purposes), after which this derivation will be extended to the rubberlike molecules with double bonds.
An Electrophoretic Study of the Proteins in Rubber Latex Serum
Authors: Roe Charles P. , Ewart Roswell H. 
Published: February 2011

Abstract
1. The serum from unpreserved rubber (Hevea brasiliensis) latex contains seven electrophoretically distinct protein components. The proteins from whole serum originating in Sumatra and Florida give very similar results in electrophoresis experiments. 2. The relationship between electrophoretic mobility and pH has been determined for five of the seven protein components of unpreserved total latex serum. The results are considerably different from those reported by workers with ammonia-preserved latex, and tend to clarify observed differences in the stability behavior of unpreserved and preserved latex. 3. Ammonia-preservation treatment rapidly alters the electrophoretic behavior of the native protein components of latex serum and reduces the number of resolvable components from seven to two. 4. The preparation of dry latex protein from rubber-free latex serum can be accomplished by the vacuum sublimation of frozen serum. This process does not appear to produce important changes in the electrophoretic properties of the total serum proteins. 5. Minor modifications of the electrodes and of the standard illumination system in the electrophoresis apparatus are described.
USF, A New Crude Rubber
Authors: McGavack John , Linscott Chester E. , Haefele John W. 
Published: February 2011

Abstract
In preparing USF rubber by the preferred method, a field latex is preserved with formaldehyde as soon as possible after tapping. This chemical is effective in quickly and thoroughly stopping bacterial and enzymatic changes in the latex (Table I). Thus one of the most important sources of variability is eliminated at the start. The preserved latex is transported to the USF rubber plant and emptied into a tall settling tank; there it is allowed to stand for 48 hours for sand, dirt, and natural sludge components to separate. At the end of this time the supernatant liquid is withdrawn into a blending tank, and another charge is introduced into the settling tank. This process is repeated until the blending tank is filled. Then a fraction of the well-mixed latex from this tank, equal to a charge added from the settling tank, is removed for processing. The latex to be processed is highly diluted, acid is added, and the whole mass is stirred. Fine floes form on standing and rise to the surface, leaving a clear yellow serum. This is withdrawn, and the flocculates are washed by the further addition of water. The washed flocs are transferred through a pipe to the coagulating tanks normally used for preparing sheet rubber. The flocs have now become sufficiently destabilized, so coalescence to a slab of coagulum may occur by simple standing at air temperature. However, faster coalescence is obtained by brief mild treatment with steam. The coalesced slab is removed and passed through mills for the production of crepe or sheet. The wet rubber is hung up to dry in a conventional dryhouse. Finally the dried rubber is heavily compressed and shipped in rubber-wrapped bales. This process is described in the flow sheet of Figure 1.
Brittle Temperature of Rubber under Variable Stress
Authors: Kemp A. R. , Malm F. S. , Winspear G. G. 
Published: February 2011

Abstract
1. The temperature at which natural and synthetic elastomers fracture on bending depends on the rate of application and the magnitude of the stress applied. The slower the rate of bending and the less the angle of bend, the lower will be the temperature of fracture. 2. A study of the stresses under varying types of service at subzero temperatures must be made in order to select intelligently the laboratory test conditions which will best simulate performance in the field. 3. In the case of synthetic elastomers having high fracture temperatures, the addition of certain types of plasticizers serve to correct this difficulty.
Preventing the Bacterial Oxidation of Rubber
Authors: Dimond Albert E. , Horsfall James G. 
Published: February 2011

Abstract
The recent article by ZoBell and Grant notes the attack of rubber by bacteria under conditions of high moisture. It is suggested that “the life of rubber products which come in contact with moisture may be prolonged if ways can be found to retard or prevent the activity of rubber oxidizing microorganisms”. In the compounding of rubber commercially, native rubber is mixed with a number of chemicals, each of which serves a specific purpose in the properties of the finished product. Among these are accelerators which lower the temperature and shorten the time of vulcanization and lengthen the life of rubber. Two well-known accelerators are mercaptobenzothiazole and tetramethylthiuram disulfide. These compounds have been tested for their ability to inhibit germination of fungi, and gross observations have been made on their ability to inhibit bacterial growth. Mercaptobenzothiazole is a moderately good fungicide, and tetramethylthiuram disulfide is excellent. The latter compound is now being marketed as a seed protectant and for the prevention of turf diseases. Both of these materials have been tested, under field conditions prevailing in Connecticut, by the authors for their efficacy in controlling plant diseases. Mercaptobenzothiazole, although inferior to tetramethylthiuram disulfide, has given partial plant disease control.
X-Ray Study of Reactions Involving Accelerators. Orientation of Crystalline Phases on Stretching of Rubber Stocks
Authors: Clark G. L. , LeTourneau R. L. , Ball J. M. 
Published: February 2011

Abstract
About a year ago, in the course of a systematic survey of the x-ray diffraction patterns of a number of routine rubber samples with different accelerators present, certain similarities were noted in the diffraction effects from the accelerators in these stocks. Close examination of these effects showed that they were identical. The stocks contained the accelerators tetramethylthiuram disulfide, tetramethylthiuram monosulfide and zinc dimethyldithiocarbamate, which are chemically similar (Table I); the first is the disulfide, the second, the monosulfide, and the third, the zinc salt. Thus, the diffraction patterns indicate that, on curing, the disulfide and the monosulfide in the presence of sulfur react with zinc oxide to form the zinc salt. This is not a new concept. The zinc salts have been extracted with solvents from stocks similar to the above, and it has been supposed that such reactions occur. However, the extraction method leaves some doubt as to whether the salt was originally present in the rubber matrix or whether it was formed in the solvent on extraction. Every crystalline material has its own characteristic x-ray diffraction pattern, which is different from that of every other crystalline material, just as the fingerprints of each person are different from those of every other person. Thus, with x-ray “fingerprint”patterns it is possible to identify positively the presence of these salts in the rubber matrix and show that they must have been formed in the rubber mix on curing. Further, it was noted that this crystalline salt is strongly oriented in the rubber matrix on stretching. It seemed advisable, then, to investigate other similar reactions by the x-ray method and to investigate the significance of the strong orientation of these reaction products in the rubber matrix.
A Direct Determination of Rubber Hydrocarbon. Chromic Acid Oxidation Method
Authors: Burger V. L. , Donaldson W. E. , Baty J. A. 
Published: February 2011

Abstract
A method for the direct determination of rubber is reported. This method utilizes the property of rubber hydrocarbon when oxidized by chromic acid to form definite and reproducible amounts of acetic acid. This determination has been reduced to a comparatively simple laboratory procedure, whose accuracy (in the absence of interferences) is 1 to 2 per cent.
Digest of Cooperative Test Program on Accelerated Light Aging of Rubber
Authors: Ingmanson J. H. 
Published: February 2011

Abstract
The Eveready unit without filters and the Atlas Twin-arc Weatherometer effect a more rapid deterioration of vulcanized rubber on exposure than does ourdoor exposure in summer. The degree of acceleration varies with the particular compound tested. In these tests it was found that from 0.6 to 3.0 hours' exposure in the machines, depending on the compound, was equivalent to 1 day of outdoor summer exposure. The procedure followed in making Eveready tests is not sufficiently standardized to obtain satisfactorily comparable results in several laboratories, with a wide variety of compounds. The Atlas single-arc equipment shows little acceleration in aging rate compared with the Atlas twin-arc and Eveready equipment used in these tests. No broad conclusions can be drawn from the results of tests in the Atlas twin-arc equipment, since results were reported for only one of these machines. It is suggested that measurements of the total radiation may be of greater significance than measurements in the ultraviolet region alone. Further' standardization in connection with ventilation and maintenance of a constant uniform temperature around the exposed specimens appears desirable. Further work is required to determine the effect of the thickness of the exposed sample on the rate of deterioration. If exposure periods are to be for time periods such as were used in these tests, it may be desirable to use thicker specimens.
Evaluation of Small Amounts of Synthetic Rubber
Authors: Garvey B. S. 
Published: February 2011

Abstract
In research on rubber synthesis, as in any broad program of chemical research, it is a distinct advantage to be able to do all work on a normal laboratory or test-tube scale. With rubber, however, the standard laboratory testing methods require from 200 to 500 grams of rubber for each batch. Hence it was obvious that, if the advantages of small-scale work in the preparational stages were to be realized, a new technique of rubber testing would have to be developed. The use of entirely new and unrelated procedures has two definite objections. In the first place the new procedures must be thoroughly tested and compared with the older methods of testing or with the processing and use requirements of the new rubbers. In the second place the significance of the results of such new tests can be conveyed, even to experienced rubber technologists, only after considerable interpretation of the methods. It seemed best, therefore, to modify standard rubber-testing methods so that they could be applied to very small amounts of synthetic rubber. More recently, the shortage of natural rubber has made necessary a reduction in the amount of rubber used for testing. For this purpose the same small-scale procedures are highly advantageous. While some idea of the quality of a sample of natural or synthetic rubber can be obtained from examination of the crude rubber itself, it is much better to know the physical properties of the vulcanized product. This means that one or more balanced compounds must be mixed and tested. The purpose of this paper is to describe a technique which has been developed in the Goodrich laboratories whereby, with as little as 5 grams of rubber, the stress-strain characteristics may be determined, and with 9 grams of rubber a fairly comprehensive evaluation can be made. This method has been used to evaluate polymers made on the 10-gram scale by Fryling.
The Second Mile
Authors: Sebrell L. B. 
Published: February 2011

Abstract
The title “The Second Mile” was inspired by an address given by W. E. Wickenden, of the Case School of Applied Science, on an entirely different subject. Since this title seemed to suit the synthetic rubber situation as it now exists, Wickenden's permission was secured to use the title in connection with this lecture. In its broader aspects, the paper purports to cover the present status of the synthetic rubber situation. Natural rubber will be compared with the copolymers made from butadiene and styrene, butadiene and acrylonitrile, and the copolymers generally known as Butyl rubber. These three materials were chosen for the comparative study because they are the materials which the Government proposes to use in the largest quantities to alleviate the present shortage of rubber. It is hoped that the data will give a fairly accurate picture of the comparative or relative values of these synthetic rubbers and natural rubber. There will be no discussion of the methods of manufacture, which are still more or less secret. It is proposed also to go into the probable structure of these polymers and to indicate some trends of research which might profitably be followed to improve them.
The Structure and Reactions of Rubber. A General Discussion
Authors: Whitby G. S. , Evans A. B. A. , Pasternack D. S. , Gee G. 
Published: February 2011

Abstract
Rubber Chemistby and Technology published, in its July and October 1942 issues, a series of papers comprising a symposium on “The Structure and Reactions of Rubber”, held by the Faraday Society, London, May 29, 1942. The papers were followed by critical discussions, which are assembled in the following pages, with references to the corresponding original papers.
The Plasticization of Buna
Authors: Hagen Harro 
Published: February 2011

Abstract
Recently oxidative thermal softening of Buna has come to the fore, a process which has been called “degradation”, a not too happily chosen term which suggests technical deterioration in quality. Properly speaking, there is loss in quality, just as there is considerable deterioration in quality when natural rubber latex is converted to dry rubber, a deterioration which is made still more extensive by mastication. Thus, while it is possible under laboratory conditions to make tread compounds having tensile strengths of 300–350 kg. per sq. cm. from natural rubber and latex compounds having tensile strengths of 450–500 kg. per sq. cm., the values obtainable with milled natural rubber are considerably lower. Despite this, one would not wish, except in the rarest instances, to dispense with the milling of natural rubber, since its processibility depends on the plasticization which is obtained by mastication. Thermal softening of Buna-S corresponds to the mastication of natural rubber. It has been possible to produce treads of unsoftened Buna-S with tensile strengths of 300 to 320 kg. per sq. cm. from compounds prepared in the laboratory, but these results cannot be obtained on factory mills because of the poor dispersion of fillers. With thermal softening, the tensile strengths of tread compounds made on laboratory mills would, to be sure, be somewhat lower, viz., 280–290 kg. per sq. cm. In mechanical compounds, the improved dispersion of fillers, compared with unsoftened Buna-S, would cause an increase in tensile strength. Oxidative softening is justified, not only from a processing and technical point of view, but above all because of the improvement in the finished product—provided, of course, that the degree of softening is suited to the intended application and that the optimum formula has been worked out. It would, therefore, be better to replace the derogatory word “degradation” by “oxidation” or “thermal softening”.
Cut Growth of Buna-S Compounds. A Method to Determine the Rate of Cut Growth of Buna-S Compounds
Authors: Carlton C. A. , Reinbold E. B. 
Published: February 2011

Abstract
1. A satisfactory laboratory method has been developed for measuring the rate of cut growth of Buna-S compounds. 2. Buna-S compounds are inferior to both natural rubber and Neoprene with respect to rate of cut growth. 3. Cut growth measurements made at elevated temperatures give entirely different results from those made at room temperature. 4. State of cure has a radical effect on the rate of cut growth of Buna-S compounds; the undercures are superior to normal cures or overcures.
Conductivity of Rubber Tread Stocks. Effect of Properties of Carbon Black
Authors: Cohan Leonard H. , Mackey James F. 
Published: February 2011

Abstract
The conductivity of a rubber tread stock compounded with 50 parts of carbon black increases exponentially as the particle size of the black decreases. As the crystal structure of the carbon approaches a more graphitic form, the conductivity increases sharply. Noncarbon surface components, either of the hydrocarbon or carbon oxide type, decrease the conductivity. This effect is less important than particle size or crystal structure. However, increases in conductivity or more than tenfold can be brought about by removal of surface components.
Brass-Plating
Authors: Gurney W. A. 
Published: February 2011

Abstract
Although brass-plating is the best known method of attaching rubber to iron or steel, it is still regarded in many quarters as something of an art or mystery, with a considerable element of uncertainty entering into the process. The brass-plating bath consists essentially of copper and zinc cyanides dissolved in sodium or potassium cyanide, with a total metal content of about 3 ounces per gallon. The composition of the alloy deposited varies with the ratio of copper to zinc in the bath, the pH, the temperature, the current density, and the amount of certain other substances, such as ammonia. Most writers on the subject have endeavored to eliminate the uncertainty by a rigorous specification of the formula of the plating bath, and the conditions under which it is to be used. In his experience, however, the composition of a plating bath can vary widely, and still give plating satisfactory for adhesion. The composition of plate deposited depends on a balance of several factors, and in most published formulas, one or more of these factors is omitted. For example, the pH is often not specified and yet it is possible to deposit a range of brasses from pure copper to pure zinc merely by the change in pH, in any particular bath.