bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthetic Rubber. Its Industrial Production in the U. S. S. R.
Authors: Akobzhanov I. G.
Published: February 2011

The subject of synthetic rubber has not been neglected in the literature. However, all the publications, including those of Harries or some of the work of Dubosc and Luttringer or even the less complete works such as articles by Jacobs and by Whitby and Katz, contain systematic discussions of the various possibilities of synthesizing rubber, but these deal only with established laboratory procedures, which are for the most part theoretical for the very reason that they have been merely abstract researches and have not been applied on an industrial scale. It should, however, be mentioned that the recent publications of Carothers and his collaborators are not of this character, and Gottlob, who described the great efforts in the Beyer and Co. plant at Leverkusen where 200 tons per month of synthetic rubber were produced during the war, should likewise not be overlooked. Nevertheless a description of this latter process is not of much practical value, because it deals with a process which was abandoned a long time ago. As far as any interest today in the industrial synthesis of rubber is concerned, there is only the work being carried out in U. S. S. R. The author would refer economists and rubber technologists who may be interested in the details to his earlier article, and the purpose of the present article is limited to a detailed survey of the chemical process as applied in the U. S. S. R., leaving out of consideration an analysis of the reasons why it has been considered necessary in the U. S. S. R. to carry out this undertaking, and why ethyl alcohol has been adopted as a raw material for the synthesis of the new rubber, and leaving out of consideration all the statistics of the development of this industry and also technical information for the use of this new substance in rubber factories.
Elastic Hysteresis and Increase in Tensile Strength at Low Temperatures
Authors: Khvostovskaya S. , Margaritov B.
Published: February 2011

1. The increase in tensile strength and the elastic hysteresis are undoubtedly conditioned by the surface processes at the boundary of rubber and filler. 2. On freezing, the optimum increase in tensile strength is shifted toward a smaller volume loading. 3. Because of the considerable increase of viscosity of the medium upon freezing, the forces of friction increase to such a degree that they mask the usual relations existing between A, R, and H for all ingredients.
The Determination of the Optimum Vulcanization by Means of the Residual Elongation
Authors: Kusov A.
Published: February 2011

As is well known, various methods have been proposed for determining the optimum vulcanization of rubber. These methods depend either upon physico-chemical examination or upon mechanical tests. In routine control the mechanical method of determination is used for the most part, because it requires but little time, and in addition this method has the advantage of showing directly by mechanical tests whether the vulcanizate being tested passes the requirements or not. The results obtained by this method frequently do not agree with those obtained by other methods. Of the many common methods of testing, determinations of the tensile strength and of the ultimate and residual elongation are the methods most frequently used. These three properties are measured simultaneously by one determination with the apparatus in most widespread use, i. e., the Schopper and the Scott machines. In special cases the resistance to abrasion, bending strength, hardness, and other properties are determined in addition. Considerably less often the hysteresis and Young's modulus of elasticity are determined. All these determinations are of significance in only a limited way, for the conditions under which the tests are carried out in the laboratory are not comparable to the actual service of the products. For basic reasons, this fundamental shortcoming cannot be avoided in the laboratory, though a few of the measurements do approach the true properties found in service. Of course, the results obtained in the laboratory are greatly influenced and made less reliable by other secondary factors, among which are the phenomenon of aging under natural conditions, prolonged stressing, etc.
Rubber in Paints
Authors: Stevens H. P. , Stevens W. H. , Heaton Noel
Published: February 2011

As a result of our previous publication (Rubber Chemistry and Technology, 7' 486 (1934)) it is now well known that oil gloss and flat paints which contain a small proportion of rubber have greatly improved flowing and non-settling properties. A flat paint made with a medium containing equal parts of rubber and stand oil requires no stippling to produce a smooth surface, but will flow out perfectly when brushed on, while pigments which quickly settle out to a hard cake in a plain oil medium can be used in the oil/rubber medium with much greater safety. Such paints soon become dust-dry after brushing out, and also have the advantage of “keeping open,” thereby enabling the decorator to brush out a large surface without fear of the paint drying at the edges and so preventing a clean “join up.” Adhesion is also good, and the paints can be used equally as well for undercoatings as they can for flat finishes. In ready-mixed oil paints the addition of a smaller proportion of rubber is sufficient to give the paint the required flowing properties, 15–20 per cent of rubber on the oil being a suitable proportion. Matters of first importance are the method of adding the rubber and the stage at which it is incorporated into the paint. The obvious way to add the rubber is in the form of a solution in the usual paint solvents. Raw rubber, however, gives extremely viscous solutions, and additions of only small proportions necessitate excessive thinning. Raw rubber also has a great tendency to cause the paint to thicken (“liver up”).
The Effect of the Conditions of Drying on the Aging Properties of Sheet Rubber
Authors: Hastings J. D.
Published: February 2011

An examination of sheet rubber prepared in identical manner up to the drying stage shows that hot-air-dried sheet and smoked sheet have different aging properties. Hot-air-dried sheet is invariably inferior to smoked sheet, except when prepared from very dilute latex. Further work is required before any explanation is offered.
Properties of Higher Polymers in Solution. III. The Action of Ultra-Violet Light on Dissolved Rubber
Authors: Meyer Kurt H. , Ferri Cesare
Published: February 2011

The action of ultra-violet radiation on rubber has been the object of a long series of investigations. According to van Rossem, rubber is depolymerized under the action of light. Asano on the other hand thinks that ultra-violet light, is able to bring about either polymerization or depolymerization according to its wave-length. More recently Dogadkin and Pantschenkov have carried out experiments in an atmosphere of nitrogen, during the course of which they have found a strong diminution in the viscosity. From this fact they have concluded that light is able to cause depolymerization and micellar degradation. We have undertaken a study of the action of ultra-violet light on rubber in order to prove whether the double cis-linkages of rubber undergo a transposition into trans-linkages, for numerous instances are known where light causes these cis-trans-transpositions. In the case of rubber, one should obtain, therefore, either a hydrocarbon of the gutta-percha type or, if light causes a sort of cis-trans-equilibrium, a hydrocarbon with double cis-linkages distributed irregularly. In our experiments we were extremely careful to exclude oxygen, since some years ago Henri proved that ultra-violet light activates greatly the oxidation of rubber. On the other hand it is known that oxidation causes a diminution in the length of the chains which modifies considerably the physical properties, for example, the viscosity, and which may mask the effect produced by light.
Production of Gasoline by Means of Hydrodepolymerization of Rubber
Authors: Kobayasi Ryo^nosuke , Furihata Minao , Kajimoto Shunji
Published: February 2011

Hydrogenation applied to the production of motor fuels from rubber has recently been investigated (C. M. Cowley and J. G. King, J. Soc. Chem. Ind., 54, 177T (1935)), but this must not be confused with the much more simple hydrogenation process employed in the hardening of fat oils, for a substance of such high molecular weight as rubber may be depolymerized into hydrocarbon oils of much lower molecular weight by hydrogenation, so the process is described more accurately as “hydrodepolymerization.” A further important fact concerning the hydrodepolymerization of rubber is that the product probably contains very large amounts of iso-paraffin hydrocarbons. The present authors naturally assume that motor fuels thus obtained are of high knock-rating, since branched-chain paraffin hydrocarbons have much higher knock-ratings than their straight-chain homologs (Lovell, Campbell, and Boyd, Ind. Eng. Chem., 23, 26 (1931)). The following experimental results prove this assumption correct.
The Oil Resistance of Rubber. III. Viscosities and Molecular Polarizations of Rubber Solutions
Authors: Lambara Shû
Published: February 2011

The molecular polarization of crude rubber has no relation to the viscosities of its solutions. For instance, ultra-violet irradiation of crude rubber solutions reduces their viscosities, but does not change essentially their molecular polarizations. With increased refining of crude rubber, its polarization increases, as shown in Experiment B and in the previous work. This may be caused by autoöxidation of purified rubber, which contains a lower proportion of impurities which act as natural anti-oxidants. It is probable that by such autoöxidation, oxygen combines at the extremity of the rubber molecule, where free isoprene bonds remain. If thread-like molecules of rubber exist, as maintained by Staudinger, a decrease of molecular polarization with reduction of viscosity which results by “cracking” of such long molecules should be observed. Such an effect was not obtained in this experiment. From this point of view, the macro-molecular theory of Staudinger seems to be questionable. The molecular polarization of rubber extracted by acetone for 40 hours and dissolved in benzene in an atmosphere of nitrogen is far smaller than that of purified rubber which has been refined with access of air. By ultra-violet irradiation in nitrogen of the rubber solutions having small polarization, there is no remarkable increase in the polarization of the rubber. From these experiments it is concluded that rubber is a substance having a small polarity, and that it dissolves in benzene in a micellar state or a more complex state having some “structure, ” but not as thread-like molecules.
Iron Oxide as a Substance for Increasing the Adhesion of Ebonite to Metal
Authors: Bartenev S. , Zhuravlev A. , Lozovskaya I.
Published: February 2011

1. Information from various sources on the increase in adhesive strength between iron surfaces and ebonite brought about by the inclusion of iron oxide in the ebonite was confirmed. 2. In all tests the best results were obtained with ebonite samples No. 1 and No. 2 with addition of 8.2 per cent of red iron oxide (20 per cent based on rubber). 3. Inclusion of 8.2 per cent of red iron oxide in the cement increased the adhesive strength between an iron plate and ebonite 260 per cent measured by the rupture under direct tension as shown in Fig. 1, and 233 per cent measured by the method shown in Fig. 2. These results were confirmed in factory production. A new formula for ebonite cement containing red iron oxide was developed, which considerably increased the adhesive power. In conclusion it should be stated that previous to the laboratory experiment, red iron oxide was used for one year in ebonite formulas for magneto parts. As is well known, most of the parts of a magneto consist of ebonite and cadmium-coated copper armature. However, it has been considered hitherto that red iron oxide acts only as a coloring agent. Red iron oxide is evidently a valuable ingredient for securing strong adhesion between ebonite and metal. Since the Kautchuk factory has adopted the use of red iron oxide in the production of ebonite, the percentage of rejections caused by the separation of armature from ebonite in magnetos had been considerably reduced. This subject requires further experimental confirmation, and the results will be reported in forthcoming publications.
Fundamental Studies on the Attributes of Organic Accelerators. XII. Action of Organic Bases on Rubber Sols
Authors: Shimada Keiiti
Published: February 2011

1. To confirm the action of organic acids on rubber sols, small proportions of butyric, valeric, propionic, monochloroacetic, bromoacetic, p-bromobenzoic, and o-iodobenzoic acids, respectively, were added to dilute solutions of rubber in benzene, and the viscosity-time curves were determined for each case. 2. That organic acids, as in the case of organic bases, cause the disaggregation of rubber was determined from the character of the changes in the viscosity when the acids were added. 3. Among organic acids, only o-iodobenzoic acid caused a lowering of the viscosity of a rubber sol, similar to the lowering by the author's C-type accelerators, and the depolymerization of rubber caused by the addition of this acid is due to the presence of iodine in its molecule. Furthermore, the characteristic behavior of C-type accelerators with rubber sols is attributable to the presence of such reactive groups in the molecule.
Determination of Total and Free Selenium in Vulcanizates
Authors: Cheraskova E. , Veisbrute L.
Published: February 2011

The total selenium in rubber compounds may be determined by disintegrating with nitric acid and then separating the selenium by reducing the nitric acid solution with hydrazine sulfate, or by reducing with sulfurous acid after evaporation of the nitric acid. Free selenium is determined by extracting the rubber with aqueous sodium sulfite, from which selenium is precipitated by formalin. Free sulfur is determined volumetrically by iodometric titration after precipitating selenium from sulfite solution.
Self-Vulcanizing Cements
Authors: Fabritziev B. , Buiko G. , Pakhomova E.
Published: February 2011

By self-vulcanizing cements is to be understood cements, films of which at regular room temperature assume within a period of one or two days a vulcanized state. As implied by this definition, self-vulcanizing cements must be based on exceedingly active accelerators. The ultra-accelerators regularly used, such as thiuram disulfides, “Zimate,” and so forth, are not suitable for the purpose. We tested them in our preliminary work, and have proved their inadequacy in this respect. Nevertheless the industry used, under the name of self-vulcanizing cements, cements based on these accelerators. In self-vulcanizing cements accelerators with the lowest critical temperature must be used. Of those available, we chose Vulkacit P, Pipsol X, and zinc butylxanthate, and have established their critical temperature of vulcanization, with the following results: Critical temperature for tetramethylthiuram disulfide 110° C. Critical temperature for Vulkacit P 60° C. Critical temperature for Pipsol X (American) 60° C. Critical temperature for zinc butylxanthate 59° C. On the basis of the above results, we chose zinc butylxanthate. For an activator we used p-toluidine, the critical temperature of the accelerator being lowered from 50° C. to 40° C. by the p-toluidine. It was with this combination of zinc butylxanthate and p-toluidine that we carried out our next work on the following lines: 1. Development of a cement formula. 2. Testing the cement of the chosen formula under laboratory conditions by cementing leather specimens or canvas with rubber, and separating same after curing them in different conditions. 3. Study of gelling in the process of storing cements.
Crystals and Fused Substance in Stretched Rubber. (A Preliminary Communication)
Authors: Thiessen Peter A. , Wittstadt Werner
Published: February 2011

When rubber is stretched, the arrangement of the molecules in the space lattice does not come to an end when the elongation is terminated, but continues for a certain time afterward. The final state of orientation for any elongation depends upon the temperature in the sense that within a wide temperature range there is at each temperature a definite ratio between the quantity of crystallized substance and the glass-like fused component. Within this temperature range, the proportion of crystallized substance diminishes with increase in temperature. This change is reversible, and the equilibrium is greatly influenced by the pressure. It may be considered as an established fact today that natural rubber is essentially a mixture of various polymers of an unsaturated hydrocarbon. At ordinary temperatures and in the absence of mechanical stress, it is an isotropic glass, both in the raw and vulcanized states. When deformed mechanically, particularly when stretched, it becomes anisotropic, a change which is evidenced by the appearance of an optical double refraction and an x-ray fiber diagram. This phenomenon is attributable to an orientation of the molecules in the direction of stretching and their arrangement into a space lattice which can be measured and defined accurately. The increase in double refraction as well as the clearness of the reflection interference pattern in the Roentgen diagram is proportional to the degree of elongation of both raw and vulcanized rubber, and it is reversible after a certain time of relaxation. In natural rubber, the reversibility of the phenomenon is disturbed by flow phenomena, which upon prolonged mechanical stress lead to permanent deformation. In well vulcanized rubber these phenomena are of little significance over a wide range of temperatures.
Natural and Synthetic Rubber. XV. Oxygen in Rubber
Authors: Midgley Thomas , Henne A. L. , Shepard A. F. , Renoll Mary W.
Published: February 2011

It has been shown that natural rubber conthins oxygen, while synthetic rubber is oxygen free. This oxygen appears to be of an hydroxylic type, and its quantity corresponds to about one hydroxyl group for each one thousand isoprene units of the rubber molecule. Rubber has been allowed to oxidize and a mechanism is proposed to interpret the quantitative data recorded.
Uniform Vulcanization
Authors: Leduc Henri
Published: February 2011

All rubber technologists are familiar from experience with the difficulties of vulcanizing objects which are bulky, thick, or porous, and they are as well informed as the writer on this problem. The properties of a vulcanizate reach their maximum at a certain cure which is defined by a certain temperature and a certain time. Rubber is a very poor conductor of heat, and up to the present time it has been necessary in order to cure it to have the surface of the object in contact with a hot fluid or a hot surface, in which case the heat penetrates with difficulty into the mass, and its distribution is far from uniform. It is clear therefore that the uniform curing of large masses is almost impossible in spite of any artifice employed. To make evident the order of magnitude of the differences in the state of cure, two experiments will be described. (1) A cylindrical iron mold, 105 millimeters in diameter and 60 millimeters high, was constructed with a cavity for a thermometer at its middle point. The mold was filled with a mixture composed of:
Contribution to the Study of the Vulcanization Reaction
Authors: Meyer Kurt H. , Hohenemser W.
Published: February 2011

In spite of the great technical importance of vulcanization, the chemical reaction involved is not yet entirely understood, although at the present time it is assumed that chemical phenomena take part in this operation. To C. O. Weber in particular is due much of the research in the field of rubber. It was he who proved the chemical combination with sulfur. He assumed that during hot vulcanization, sulfur combines with two polyprene chains and that they unite chemically, but he was not able to go into this subject in more detail or to prove anything further. The process of cold vulcanization is better understood. There are good reasons for assuming that sulfur chloride reacts with the double bond of polyprene chains in the same way that it does with olefins of low molecular weight, for example with ethylene. It is known that sulfur chloride unites with this latter according to the following scheme:
The Oil Resistance of Rubber. II. Molecular Polarization and Dipole Moment of Purified Natural Rubber
Authors: Kambara Shû
Published: February 2011

Natural rubber was purified by Pummerer's method and was dissolved in benzene and ether. The dielectric constant, refractive index, density, and concentration of the solutions were determined. From these data, the molecular polarization and dipole moment were calculated on the assumption that the rubber was dissolved in a molecular state of (C5H8)8. The dipole moments of total and gel rubber were found to be 2.45 and 2.91 × 10−18, respectively. These values are of the same order of magnitude as those of masticated crude rubber obtained by Ostwald. It may be said that the impurities of rubber are interlocked mechanically on the rubber molecule and are not combined chemically. Sol rubber in ether solution shows a far lower value than the values of total and gel rubber. These latter values may be influenced by autoöxidation, and the true value of the rubber hydrocarbon may be far smaller than the result described in this paper.
Studies on Chlorinated Rubber
Authors: Yamamoto Tatsumi
Published: February 2011

1. In the chlorination of rubber, the products have different combined chlorine contents which depend on the time of chlorination, but the final chlorination product seems to be C10H13Cl7, i. e., contains 64.7 per cent of chlorine. The rubber molecules disaggregate with advancing chlorination and the viscosities diminish. Accordingly the viscosity of rubbers containing the same chlorine contents vary with different conditions of preparation. 2. The properties of chlorinated rubbers vary with differences in their combined chlorine content; for a product to be thermostable and have high resistance to chemicals, it must contain over 60 per cent of chlorine. 3. The best method is to dissolve the pale crepe or F. A. Q. sheet in carbon tetrachloride and pass chlorine through the solution continuously while heating at 70–80°, with agitation. The reaction product is then separated from the solvent by distillation until the last trace of the solvent is removed, and is then washed with water free from acid impurities. 4. Chlorinated rubber has a high resistance to acids and alkalies and, above all, the permeability of films to water vapor is less than that of benzylcellulose. Moreover, chlorinated rubber is not explosive, and burns with difficulty. 5. The stability of four commercial products was studied, and an imported sample which had high stability was found to contain a stabilizer. Among various stabilizers tested, urea had the most beneficial effect. 6. As to the value of chlorinated rubber for varnish, there are many reports, and it is still in an experimental stage; but it has many properties which give the hope that it may be used as a special varnish after further studies by manufacturers and consumers. 7. By molding powdered chlorinated rubber under pressure and heat, a plastic which was easily removed in a short time was made. Its mechanical and electrical properties were tested and it gave attractive products with many pigments. Chlorinated rubber can be used as substitutes for plastics such as Bakelite or ebonite.
X-Ray Study of Amorphous Rubber
Authors: Simard G. L. , Warren B. E.
Published: February 2011

The density of surrounding atoms in unstretched rubber is determined by a Fourier analysis of the x-ray scattering curve. The resulting distribution curve is in good agreement with the usual picture of rubber as comprised of long chain molecules. It is concluded that but little information can be obtained as to the configuration of the chains in unstretched rubber.
A Rapid Method for Determining Sulfur and Ash in Rubber by Ignition of the Rubber in Oxygen
Authors: Kreps B.
Published: February 2011

1. The rapid method of determination of total sulfur and ash by ignition of rubber in a current of oxygen is not less accurate than the method of Henriques. 2. The proposed method can be used with all kinds of rubber mixtures except those containing litharge. 3. In the analysis of mixtures containing barytes, all sulfur except that contained in barytes is determined. 4. The method is particularly useful in the determination of sulfur and ash in Resinites (Thiokol), and the sulfate can be determined by the volumetric method.
An Improvement on the Williams Abrasion Tester
Authors: Ookita Tadao
Published: February 2011

The Williams abrasion apparatus for rubber has various structural defects which are discussed. Certain improvements were therefore made. 1. It was proved experimentally that the effect of the humidity of the testing room is great, and that it is necessary to remove the abraded powder by a current of dry, compressed air. 2. It was found that emery paper can be used for five successive tests, but in this case there were 20 per cent variations, and 70-mesh carborundum whetstone was found necessary to reduce the errors. The maximum deviation with this whetstone was ±5 per cent with twenty rubber samples. If this 5 per cent deviation is acceptable, carborundum can be used for 100 hours or 300 continuous tests. 3. The spring balance was constructed with an automatic recording device in order to obtain accurate weights. This improvement and the improvement of the abrasion surface increased the precision of the original Williams apparatus. 4. It is shown that large errors are encountered in testing more than two different samples at one time, as is the case in testing metals. This seems to be connected in some way with the hysteresis of the abrasive surface.
Determination of Free Sulfur in Rubber
Authors: Oldham E. W. , Baker L. M. , Craytor M. W.
Published: February 2011

Values obtained by the volumetric method herein described compare favorably with those obtained by gravimetric methods when corrections are applied to the latter for the sulfur in the organic compounds in the acetone extract. The precision of the method is excellent, as duplicates in each set usually check within 0.01 per cent of free sulfur on the compound. This method is much faster than previous methods. The cost of the reagents is low when compared with most other methods.
The Electro-Deposition of Rubber from Revertex and Revultex
Authors: Budiloff N.
Published: February 2011

1. It was found that to obtain satisfactory deposits at the anode from Revertex, a certain quantity of ammonia must be added to the Revertex. 2. It was found that the quantity of rubber deposited depends upon the quantity of electricity, the current density, and upon the concentration of rubber in the Revertex. 3. It was found that, among the metals studied, only zinc and cadmium or metals coated with zinc can be used for the anode. 4. The problem of obtaining on the anode faultless rubber deposits from diluted Revertex (1:1) after the addition of sulfur and fillers was solved. On the contrary, it was not possible to obtain satisfactory deposits at the anode from dilute Revultex containing fillers, with the exception of carbon black and coloring agents.
Studies in the Interfacial Relationships between Rubber and Fillers. I. The Tear Resistance of Vulcanized Rubber
Authors: Lefcaditis G. D.
Published: February 2011

1. Interfacial affinity of rubber for fillers is suggested as mainly responsible for the phenomena of tear resistance and resistance to abrasion of vulcanized rubber mixes, whereas “reinforcement,” as indicated by increase in tensile strength and resilient energy, is thought to be caused partly by mechanical effects such as friction and thin film formation. Anisotropic fillers are particularly liable to develop such mechanical effects, and thus produce a type of reinforcement which need not necessarily imply increased resistance to wear. 2. Considerable importance is attached to the supposed fibrous network structure of rubber, indicated by recent x-ray work. Gradual destruction of the network during mastication is considered as the cause of the decrease in tear resistance of vulcanized products from overmilled rubber. Similarly the high tear resistance of latex rubber is explained by assuming the framework unimpaired. The fillers in this case are believed to play a secondary role. 3. The cause of grain effect resides in both the filler and the rubber phase. Isotropic fillers of high affinity for rubber can produce strong grain effect, due to fixation of orientated elementary rubber fibers. 4. The tear resistance and other mechanical properties of a vulcanized rubber compound are functions of the disaggregation of the rubber during milling and mixing, the speed of the accelerator, and the temperature of vulcanization. The best physical properties with any particular compound were obtained when it was either produced direct from latex or by milling in nitrogen. The faster the accelerator employed, and the lower the temperature of vulcanization, the better the physical properties of the vulcanized product.
Zinc Oxide in Rubber
Authors: Depew Harlan A.
Published: February 2011

THERE are few secrets in the zinc industry, as in most industries, but there has been a reticence to permit the publication of articles regarding the industry that has reacted to its detriment. There is, accordingly, comparatively little literature, and much of that part of this paper that relates to the manufacture of zinc oxide is taken from carefully selected patents. The validity of many of these is questionable, since they have never been litigated, and no claims are made regarding their value except that they describe the processes used in the industry more satisfactorily than can be found elsewhere. The methods of making zinc oxide can be only outlined in the space available, and it is to be hoped that additional information will be presented by those who find the discussion incomplete.
The Influence of Rubber “Resins” in Zinc Oxide—Accelerator Mixings
Authors: Davey W. S.
Published: February 2011

There is no doubt that the natural fatty acids in rubber have important effects on the vulcanization of many mixings containing an organic accelerator and zinc oxide. The majority of workers who have investigated these effects have confined their attention to, and drawn their conclusions from, experiments with mixings containing about 5 parts of zinc oxide per 100 parts of rubber. Martin and Davey have shown, however, that a number of accelerators which require the help of fatty acids in the presence of 5 parts of zinc oxide are very effective without fatty acids when much larger quantities of zinc oxide are present. They have suggested that the function of the fatty acids is to prevent the flocculation of the zinc oxide and so increase the surface available for reaction with the accelerator. This is important in mixings containing low proportions of zinc oxide, but not in the case of mixings containing high proportions where there is much more than sufficient zinc oxide to satisfy the requirements of the accelerator. Whitby and Evans, however, favor the view that fatty acids are generally essential to vulcanization in the presence of large quantities of zinc oxide, and that the function of the fatty acids is to form a zinc compound soluble in rubber, which is then capable of reacting with the accelerator. It is suggested that there is no reaction between insoluble zinc oxide and most accelerators.
The Constitution of Rubber
Authors: Pummerer R.
Published: February 2011

According to the results of research which has been carried on until now, the rubber formula can hardly be formulated without a ring system. It has either a very large, closed ring of isopentene groups, or a long chain, somewhat as in Formula II, in which the terminal isoprene group has disappeared through ring formation. It is the problem of organic preparative chemistry to carry on in the most exact way the by-no-means hopeless search for the end members of the long-chain 210 natural products, and not to rely wholly upon the results of physical methods alone. The imagination of organic chemists must still more than before seek to trace the characteristic reactions of the end groups, which differ from the remaining chain members. For proteins, the determination of the increase of free terminal amino groups and carboxyl groups in cleavage reactions is already an important method of investigation, and with polysaccharides the reaction of hypoiodite with a free terminal aldehyde group has been carried out with success by Bergmann for determining the length of the chains. In the field of high molecular natural substances, which is so difficult to investigate, we shall consider a concept as certain only if it is supported equally by the results of chemical as well as physical methods of investigation.
The Behavior of Ebonite towards Organic Liquids
Authors: Scott J. R.
Published: February 2011

(a) Experiments are described on the swelling of rubber-sulfur ebonites in numerous organic liquids, with special reference to the influence of the nature of the liquid, the ratio of rubber to sulfur and time of cure of the ebonite, and the temperature. (b) The rubber-sulfur compound constituting ebonite is not appreciably soluble in any of the liquids examined at 34° C. or in aliphatic hydrocarbon liquids at 100° C. (c) Ebonite may absorb as much as its own volume of some liquids but is quite unaffected by others. (d) The swelling curve often shows the same features as that for soft vulcanized rubber, but an important difference arises when the absorption is large, because the absorbed liquid progressively increases the diffusion constant and so changes the shape of the curve. For the same reason, also, the swelling capacity of the liquid has a greater influence than its viscosity on the time required to reach maximum absorption. (e) Increasing the combined sulfur content of the ebonite reduces the amount of liquid that it will absorb and renders the absorption much slower. In making ebonite to withstand the swelling action of organic liquids, therefore, the aim should be to obtain, by using an adequate proportion of sulfur and sufficiently long vulcanization, the highest combined sulfur content consistent with the required mechanical properties; over-vulcanization, however, may be detrimental. It should be noted that slowness of absorption is in itself an important advantage in uses involving only intermittent periods of contact with volatile liquids which can dry out again between these periods. (f) The extent to which swelling is reduced by increasing the combined sulfur content from the soft rubber stage to the ebonite stage varies greatly with the nature of the swelling liquid. Two important consequences of this are: firstly, with aliphatic hydrocarbon liquids the swelling action practically vanishes when the ebonite stage is reached; and secondly, conclusions regarding the swelling of ebonite cannot be based on data for soft rubber, because the relative swelling effects of various liquids are quite different in the two cases. (g) The inertness of aliphatic hydrocarbons such as paraffin and transformer oil towards ebonite persists at temperatures up to 100° C, that is, far above the “yield temperature” or softening point of the ebonite.
Permeability of Organic Polysulfide Resins to Hydrogen
Authors: Sager Theron P.
Published: February 2011

A characteristic of balloon and airship fabrics which is of prime importance is that they shall be gas-tight or nearly so. The inherent tendency of hydrogen and of the more costly gas helium to diffuse through thin membranes of rubber provides the incentive for the study of the behavior of a large number of film-forming materials in a search for a more satisfactory material. Considering all of the requirements involved in this application, the permeability of the group of synthetic polymers which are characterized by elastic extensibility has been of particular interest. The general reaction between organic dihalides with—CH2Cl terminals and inorganic polysulfides yields products which in many cases are characterized as rubber-like. Martin and Patrick suggested that the structure of the polysulfide resins is that of long-chain polymers in which the radicals are connected through disulfide linkages and represented as —R—S—S—R—S—S—R—. According to their hypothesis, any additional sulfur in the material in excess of that required to provide the disulfide linkages is believed to be coördinately linked to the sulfur comprising the disulfide linkages.
Bonding
Authors: Habgood B. J.
Published: February 2011

1. Neoprene and rubber can be bonded directly, provided that: (a) the composition of the two stocks are balanced; (b) the stocks are kept warm; (c) bonding is carried out with the minimum of delay. 2. Neoprene and rubber can be bonded by other methods which give greater latitude of working: (a) by the use of a high concentration of accelerator at the interface; (b) by the use of a tie-gum mix made from butadiene rubber (preferably sodium-polymerized); (c) by the use of mixtures of Neoprene, chloro derivatives of rubber, either alone or admixed with rubber. Partially hydrochlorinated rubber is particularly useful in this direction. 3. Synthetic rubbers can be bonded one to another or to natural rubber either directly or through the medium of sodium-butadiene rubber. 4. The bonding of rubber to metal has been considered and the main methods discussed, including bonding by means of ebonite; alloys, particularly brass; cyclorubbers, Thermoprenes, and cements. 5. The bonding of synthetic rubbers to metals has been examined and a new method of bonding Neoprene to a variety of metals, including iron, steel, aluminum, zinc, and lead, has been worked out, using a solution of chlorinated rubber as bonding agent. 6. By combining the various methods described in this paper, rubber may be bonded to metals such as aluminum without brass plating.
A Contribution to the Early History of India-Rubber. François Fresneau (1703–1770)
Authors: Hauser E. A.
Published: February 2011

In the fall of 1936 the Revue Générale du Caoutchouc published a special issue dedicated to the memory of the French scientist La Condamine on the occasion of the bicentenary of the discovery of rubber. Quite recently the same periodical issued another special number on the occasion of the International Exposition in Paris, 1937. The title page reproduces Cochin's well-known portrait of Charles Marie de la Condamine. The first paper by Ch. Jung, entitled “History and Development of the Rubber Industry,” gives all the credit of the discovery of rubber to Condamine, and for the details refers to the publication mentioned above. In the bicentennial number, Henri de la Condamine gives a detailed biography of his ancestor, wherein the name of Fresneau as a correspondent of Condamine is mentioned in a few places. A second paper, by Auguste Chevalier, deals chronologically with the various publications presented by Condamine, and here Fresneau receives as much credit as can be justified from the contents of these papers. Finally, we owe a revival of the correspondence between Fresneau-Condamine and the French Minister of Colonies Bertin to J. Ch. Bongrand. However, when one considers the exceedingly courteous phrases and carefully couched terms characteristic of letters of that period, and bears in mind that this correspondence only refers to the last years of Fresneau's life, such documents alone cannot be taken by the historian at their full value.
Tensile Tests with Flat (Straight) Test-Specimens
Authors: Ariano R.
Published: February 2011

It is of course a well known fact that both ring test-specimens and flat or straight test-specimens are used in testing rubber. Ring test-specimens have for a long time been the most generally used type for testing rubber mixtures, whereas in American laboratories straight test-specimens are preferred. Ring test-specimens are the more convenient to use, but they are open to one fundamental objection, that different parts of the cross section of the rubber are elongated to different extents at any particular moment. Even straight test-specimens are not free from objectionable features. With this type of test-specimen, the inequality in the deformation at any particular instant results from the necessity of having enlarged ends for the testing machine to avoid breakage of the test-specimens in the jaws. It therefore becomes necessary to study systematically the form and dimensions of the end sections of the test-specimens and of the junction of these end sections with the central section, so that the points of rupture will not become localized in the sections in the jaws or close to these sections. As a matter of fact, an extensive investigation of this problem has been made by the Physical Testing Committee of the Rubber Division of the American Chemical Society. By a proper study of the shape of the test-specimen, it is possible to design the test-specimen so that rupture occurs in the center section and therefore so that satisfactory tensile strength measurements are obtained.
X-ray Diffraction Patterns of Sol, Gel, and Total Rubber when Stretched, and when Crystallized by Freezing and from Solutions
Authors: Clark George L. , Wolthuis Enno , Smith W. Harold
Published: February 2011

Sol, gel, and total rubber were prepared by a method which avoided the effects of light and oxygen. The total rubber when stretched and exposed to an x-ray beam behaved like other specimens, and produced the characteristic crystal fiber pattern. Stretched sol rubber produced no evidence whatever of this pattern, even at 1000 per cent elongation. With stretched gel rubber, the pattern was formed above 100 per cent elongation and at 200 per cent was sharp and intense. The measurements of interplanar spacings agree excellently with the results reported recently by Lotmar and Meyer. A large, interplanar spacing of 54 A. U. was found in the unstretched gel. It was absent in the sol. Specimens of frozen sol, gel, and total rubber were examined with a cylindrical and with a flat-film camera to compare the spacings and intensities with those of stretched gel. Within experimental error, sol, gel, and total rubber produce similar patterns. The spacings are similar to those in stretched rubber, with the exception of the (002) spacing in frozen rubber, which is 6.18 A. U. instead of 6.30 A. U., the value in stretched rubber. The pattern of gel, crystallized from solution, is similar to the patterns of stretched and frozen rubber.
The Fluorescence of Vulcanization
Authors: Oberto S.
Published: February 2011

Ultra-violet radiation of high intensity, in most cases from mercury-vapor lamps, has been employed in the rubber industry for two different purposes: (1) as a rapid, artificial aging test intended to duplicate under controlled conditions the surface changes on rubber brought about by sunlight, and (2) as a means of analysis by fluorescent light. On this last subject alone, there is rather extensive literature; in fact, almost every product, whether raw rubber, zinc oxide, accelerators plasticizing agents, antioxidants, or carbon blacks (by means of their extracts), has been examined by fluorescent light, and with at least some measure of success. However, it is much more of a problem to develop, from a qualitative test based on the equality or inequality of color and of intensity of two samples, a quantitative and therefore more precise method of evaluation. An example of this is zinc oxide, which has been examined by Nagle, Kirchhof, Morris, and Hauser. Morris was able to show that the fluorescence of this substance is evident in the ash of a vulcanizate containing it, provided that the rubber sample is incinerated under carefully controlled conditions. But for a given process of manufacture, the fluorescence of a zinc oxide varies with its fineness.
Vulcanization of Rubber in the Presence of meta-Dinitrobenzene
Authors: Wright J. M. , Davies B. L.
Published: February 2011

Since Ostromislensky (J. Russ. Phys. Chem. Soc., 49, 1456 (1916)) claimed that vulcanization of rubber in the presence of m-dinitrobenzene entailed the addition of oxygen to the rubber molecule, it has been suggested that this form of vulcanization may be the oxygen analog of ordinary sulfur vulcanization. Blake (Ind. Eng. Chem., 22, 740 (1930)), however, extracted vulcanizates with acetone and determined the nitrogen content. If it were assumed that the unextractable nitrogen was combined with the rubber, the figures indicated that the chemical reaction was monomolecular, and in explanation it was suggested that consecutive reactions occurred, one of which was slow. The vulcanizate was concluded to be an additive compound of the vulcanizing agent with the rubber. Objects and Technic.—The objects of the present work were to answer two questions: (1) what are the reactants, and (2) in what manner do they react? It was hoped with the simplest binary mixtures to find what were the essential ingredients, and to proceed to increasingly complex mixtures to discover the roles of the various accessory substances. By vulcanization in solution it was found that the examination of the final reaction mixture was facilitated. The mixes were therefore dispersed in technical xylene, of boiling point 140° C., and vulcanized by boiling. At a particular stage, the rubber became insoluble, and the time required to arrive at this stage was a characteristic of the mix and was taken to be proportional to the rate of reaction.
Composition and Structure of Hevea Latex
Authors: Kemp A. R.
Published: February 2011

Many properties of rubber are intimately related to the composition and structure of latex from which it is made. Some of these relations, however, remain obscure since our knowledge of latex structure and of the inner properties of rubber is lacking. The purpose of this paper is to help clear up some of the important questions relating to latex and rubber structure and to discuss their possible bearing on rubber properties. Composition of Ammonia-Preserved Latex This work and that of F. F. Lucas on ultraviolet microscopy of latex were carried out on commercial ammonia-preserved plantation latex taken from fresh shipments coming from two suppliers. The chemical analyses of these latices are given in Table I and are typical, although the composition of commercial liquid latex may vary somewhat, depending on many causes which will not be dealt with here.
Ultraviolet Microscopy of Hevea Rubber Latex
Authors: Lucas Francis F.
Published: February 2011

This paper is a report of studies made on two bulk samples of commercial rubber latex by means of the ultraviolet microscope. This apparatus does not appear to have been used to an appreciable extent for the study of the rubber latex particle. Green (1) applied it to vulcanized rubber latex and apparently made some observations on unvulcanized latex. The author is indebted to A. R. Kemp of these laboratories for suggesting the microscopical studies here reported. In his paper Kemp gives chemical analyses of the two latices used in this investigation, and their composition and structure are discussed.