bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of 2,3-Dimethylbutadiene and Its Polymerization to “Methyl Rubber”
Authors: McHenry John J. , Drumm Peter J. , O'Connor William F. 
Published: February 2011

Abstract
Between 1915 and 1918 the Bayer Company in Germany produced over 2,500 tons of rubber from 2,3-dimethylbutadiene. The product, called “methyl rubber”, was not a commercial success. Its tensile strength was low and it suffered from the further drawback of being very susceptible to oxidation, as a result of which it was converted into a sticky resinous material. It is of interest to note that at this period the beneficial effect of carbon black on the tensile strength of rubbers was not known, nor had the antioxidative properties of such chemicals as β-naphthol, nitronaphthalene and bipiperidyl been discovered. In the light of this knowledge the authors considered that a reinvestigation of the properties of “methyl rubber” might be of interest. The preparation of the methyl rubber from acetone is described in the following account.
Rise of Temperature on Fast Stretching of Butyl Rubber
Authors: Dart S. L. , Guth Eugene 
Published: February 2011

Abstract
Study of the rise in temperature by fast stretching of Butyl gum and tread stocks throws considerable light on crystallization, internal friction, and carbon black reënforcement as functions of elongation and other possible variables. For low elongations, the low-heat curves show the occurrence of thermoelastic inversion. They show also that internal friction is much larger in Butyl than in Hevea. For high elongations the high-heat curves enable one to follow the late and abrupt crystallization so characteristic for Butyl stocks. The carbon black reënforcement of Butyl is followed for the whole range of elongations up to the breaking point. Specific carbon-black reënforcement takes place in the range of elongations before crystallization of the gum stock, but the shortening of the breaking elongation by the black excludes to a large extent the added reënforcement through crystallization. Physical measurements of the type reported in this paper serve a manifold purpose. They enable one to establish a correlation between physical properties and chemical structure. Such a correlation is simpler for fundamental physical properties, as the ΔT vs. ε curve, than for more complicated physical tests, as data from flexometer, which were designed to approach service conditions. Comparing different gum stocks with Butyl polymers among themselves and with Hevea or other synthetics, these measurements may guide the development of better Butyl polymers. Finally, comparing tread with gum stocks, they may help to recognize the nature of reënforcing by carbon blacks and the action of other compounding ingredients.
The Role of Oxygen in the Plasticization of Rubber
Authors: Twiss D. F. 
Published: February 2011

Abstract
The close relation between the degree of mastication of raw rubber and the plasticity of the milled rubber (or the viscosity of its solutions) has been practical knowledge since the earliest days of rubber manufacture. The first definite evidence of the possible importance of atmospheric oxygen in the plasticization of rubber dates apparently to the early days of the Research Association of British Rubber and Tyre Manufacturers1. The final Summary in its second Research Report in 1921 contained the following statements: “Raw rubber may be heated in an atmosphere of steam, hydrogen or nitrogen to a temperature of 150° C without any very great change being brought about in its solution viscosity.” “The effect produced by milling can be imitated by heating rubber in the presence of oxygen or air.” “The marked changes in solution viscosity which are produced in rubber by heating in air are due to some chemical action between the rubber and the oxygen present.” The report ended: “It is scarcely necessary to point out the importance of the above observations in connection with the changes which occur during washing, drying (both in air and in vacuo) in the milling of raw rubber and in connection with the storage of unvulcanized compounded stock.”
Determination of Peroxides in Synthetic Rubbers
Authors: Robey Richard F. , Wiese Herbert K. 
Published: February 2011

Abstract
Peroxides are found in synthetic rubbers either as the result of attack by oxygen, usually from the air, or as a residue from polymerization operations employing peroxide catalysts. Because of possible detrimental effects of active oxygen on the properties of the rubber, a method of quantitative determination is needed. The concentration of peroxides in substances of lower molecular weight may be determined with ferrous thiocyanate reagent, either titrimetrically as recommended by Yule and Wilson or colorimetrically as by Young, Vogt, and Nieuwland. Unfortunately, many highly polymeric substances are not soluble in the acetone and methanol solutions employed in these procedures. This is also the case with hydrocarbon monomers, such as butadiene, containing appreciable concentrations of soluble high molecular weight polymers. Bolland, Sundralingam, Sutton and Tristram recommended benzene as a solvent for natural rubber samples and the reagent made up in methanol. However, most synthetic rubbers are not readily soluble even in this combination. The following procedure employs the ferrous thiocyanate reagent in combination with a solvent capable of maintaining considerable concentrations of synthetic rubber in solution. The solvent comprises essentially 20 per cent ethanol in chloroform.
Determination of Unsaturation in Butyl Rubber
Authors: Rehner John , Gray Priscilla 
Published: February 2011

Abstract
In a recent publication on unsaturation in Butyl rubber it was pointed out that, of the various methods that had been examined, ozone degradation at the double bonds appears to give the most reliable unsaturation data, the values based on the limiting viscosity of the degraded polymer being in reasonably good agreement with those determined by end-group analyses. This paper describes in some detail the analytical method, together with certain modifications that have been introduced with the aim of facilitating routine work. It was recognized that the earlier procedure had the disadvantage of being too time-consuming, owing mainly to the steps in which the degraded polymer solution is evaporated to dryness, and the residue redissolved in diisobutylene before the viscosity measurement. An obvious possible improvement was to develop a procedure whereby the polymer solution could be ozonized and the viscosity of the degraded solution determined directly, thus eliminating evaporation and transfer to a second solvent. It was first necessary, however, to perform the experiments described below; their significance will be explained in the sequel. A further simplification was introduced through the use of carbon tetrachloride of ordinary reagent grade instead of the highly purified solvent. While this substitution usually leads to viscosity-time curves displaying a small negative slope in the region where the purified solvent gives unchanged viscosity values, a simple extrapolation to zero time gives viscosity data that are satisfactory within the limits inherent in the method. In view of the practical requirements of the method and the magnitude of the experimental error, the extra time and effort involved in further purification of the solvent appear to be unwarranted.
Identification of Raw and Vulcanized Rubberlike Polymers. II. Determination of Swelling Ratios
Authors: Parker L. F. C. 
Published: February 2011

Abstract
The ratios of the swellings of vulcanized rubberlike polymers in benzene, light petroleum (b.p. 40–60°), and aniline, at 25° C, have been found to be different for different polymers, but to be within a well-defined narrow range for each polymer, and the ratios substantially independent of the state of vulcanization and nature and proportion of the fillers. Hence the ratios for an unknown sample may be utilized in its identification, preferably by plotting the values on a graph showing the ratios for the common types of rubberlike polymers.
Adhesion of Rubber to Brass Plate
Authors: Gurney W. A. 
Published: February 2011

Abstract
The brass-plating process is one of the most important methods of bonding rubber to metal. It consists of depositing a thin layer of copper zinc alloy on the surface of the metal. The rubber is then moulded in contact with the brass deposit, and in most cases, a strong bond is established during vulcanization. Even, however, when all precautions are taken, bond failures occur, often with no obvious cause, so the process is still somewhat suspect. It is only fair to say, however, that this variability appears to be common to most methods of bonding rubber to metal, and that in general production a high level of adhesion is maintained.
The Structure of Polyisoprenes. V. Ultraviolet Absorption Spectra of Certain Carbalkoxy-Substituted 1,5-Dienes, and the Charge-Resonance Spectra of Glutaconic Ester Enolate Ions
Authors: Bateman L. , Koch H. P. 
Published: February 2011

Abstract
Spectral evidence supports the conclusion reached in Part IV that ring-chain mesomerism in methyl and ethyl Δ1,5-hexadiene-l,1,3,3,4,4,6,6-octacarboxylates is nonexistent in solution, just as in the crystalline state. The data are not inconsistent with chain hyperconjugation in these molecules. The marked change in structural type that follows the addition of one molecule of hydrogen or hydrolytic reagent has been verified spectrographically. The spectra of methyl and ethyl α,γ-dicarboxyglutaconic esters and their sodium and cupric derivatives have been measured in various solvents, and their tautomeric behavior compared with that of other keto-enols. Of special interest is the intense long-wave absorption band of the enolate ions, which are recognized as simple structural analogs of the cyanine dyes giving rise to similar charge-resonance spectra. A preliminary comment is made on the present accepted structure of ethyl 6-ethoxy-α-pyrone-3:5-dicarboxylate.
Strength of Amorphous and of Crystallizing Rubberlike Polymers
Authors: Aleksandrov A. P. , Lazurkin J. S. 
Published: February 2011

Abstract
The strengths of unloaded vulcanizates and the action of active fillers differ greatly according to the types of elastomers from which they are derived. These differences are not connected directly with the chemical compositions of the elastomers. Thus, for example, vulcanizates of natural rubber and synthetic isoprene rubber differ in strength in the ratio 10–15 to 1, whereas vulcanizates of Butyl rubber and of polychloroprene are very similar to natural rubber vulcanizates with respect to tensile strength. These differences in tensile strength cannot be ascribed directly to differences in structure of the chains, linear or branched; linear polymers of styrene and of methyl methacrylate “vulcanized” by small admixtures of butadiene-benzene or dimethacrylate-ethyleneglycol have, in the elastic state, tensile strengths which are just as low as those of unloaded vulcanizates of sodium-butadiene rubber or of isoprene rubber. The differences in tensile strength must, accordingly, be looked for in the different macroscopic properties of these polymers.
The Behavior of Ketene towards Olefins and Olefinic Peroxides
Authors: Naylor Ralph F. 
Published: February 2011

Abstract
Ketene will not react additively with unconjugated olefins such as 1-methylcyclohexene, dihydromyrcene, and rubber. Zinc chloride or sulfuric acid promotes reaction of ketene with acetone (carried over from the ketene generator), with the formation of a compound, C7H10O3, probably β-propenyl acetoacetate. Ketene acetylates olefinic hydroperoxides, but the resultant peracetates are very unstable.
Thermal Breakdown of Rubber
Authors: Bolland J. L. , Orr W. J. C. 
Published: February 2011

Abstract
The degradation of rubber observed during various technological processes may arise from several different causes. Since one such contributory factor is possibly degradation by a purely thermal mechanism, it is of interest to estimate experimentally the importance of this type of degradation under the temperature conditions normally used in the processing of rubber. It may be stated immediately that the authors' experiments confirm that thermal breakdown of rubber is of negligible importance under such circumstances and is always overshadowed by more efficient alternative modes of degradation. The thermal degradation of rubber, constituting as it does its formally simplest chemical reaction, has real possibilities of giving insight into the chemical stability and reactivity of the rubber molecule. Moreover, the theoretical treatment of the degradation of long-chain molecules has apparently far outstripped the experimental investigation of the problem. To date, attention has been confined to long polymeric chains which are assumed to break in quite random fashion at the regularly recurring bonds joining the monomeric units, and it is of importance to see how far this simplifying suggestion regarding the manner of chain scission does in fact correspond to reality. With these two ends in view the writers have investigated the thermal breakdown of rubber in some detail. A preliminary report is now presented on certain complexities of the reaction which may, however, be resolved by consideration of the resonance stabilization of the intermediate degradation products.
Rubber, Polyisoprenes and Allied Compounds. VIII. The Formation of Dialkyl Sulfide Dihalides, and Its Bearing on the Problem of Determining the Unsaturation of Vulcanized Rubber
Authors: Bloomfield George F. 
Published: February 2011

Abstract
In determining the unsaturation of olefinic sulfides and disulfides by halogenation methods, the addition of halogen to the sulfur atom must be taken into account. The dihalides of dialkyl or dialkenyl sulfides react with aqueous potassium iodide partly to liberate iodine with regeneration of the sulfide, and partly to form halogen acid and dialkyl or dialkenyl sulfoxides. Correction for the latter reaction, which occurs extensively in the presence of alcohol or acetic acid, must be applied before reliable unsaturation values for dialkenyl sulfides can be obtained. With vulcanized rubber and iodine monochloride, the precise magnitude of the correction to be applied is uncertain, but this uncertainty can be removed by using bromine as the additive reagent. Simple rubber-sulfur vulcanizates show a loss of unsaturation corresponding to one double bond per sulfur atom combined up to at least 8 per cent of combined sulfur; vulcanizates accelerated with mercaptobenzothiazole in the presence of zinc oxide exhibit a substantially smaller loss of unsaturation. The dibromides of dialkyl sulfides readily yield a molecule of bromine to olefins, the reaction being practically exclusively additive.
The Proöxygenic Effect and the Resulting Deterioration of Rubber
Authors: Chovin P. 
Published: February 2011

Abstract
Three particularly important conclusions can be drawn as a result of the investigation described in the present paper. (1) The proöxygenic effects of the various organic salts of copper, iron, manganese and cobalt which were tested are not confined to the surface alone. All these salts are soluble in organic solvents, and it is to be presumed that they are likewise at least slightly soluble in rubber hydrocarbon. Actually it was observed that immediately after impregnation of rubber with the solution, the proöxygenic substance had penetrated into the interior of the sample, although this penetration was not uniform. This concentration gradient resulted in a preferential attack at the surface by gaseous oxygen. This attack was manifest in the formation of a sticky surface coating which acted, to a certain extent, as an obstacle to further penetration of oxygen into the core of the small pieces of rubber. It was also observed that, after autoöxidation, deterioration of the samples was chiefly on the surface. This deterioration was very pronounced, e.g., even after only 15–30 minutes in the manometer at 80° C ; the pieces of rubber adhered strongly to one another. (2) When present as binary mixtures, salts of manganese, iron and cobalt showed true mutual exaltation effects in their catalytic activities. A mutual inhibitory effect was likewise observed in some cases. (3) In the form of ternary mixtures, and within a limited range of compositions, these same salts induced more rapid autoöxidation than was to be expected of them by application of the law of mixtures. This effect was particularly great with a eucoactive mixture of cobalt, manganese and iron salts in the proportion of 1:1:3 (based on the metals), in which case an exaltation effect 300 per cent of the calculated effect was found.
Principles of a Method of Vulcanization Based on Condensation Reactions. Prosthesis and Synesis
Authors: Dufraisse Charles , Compagnon Patrice 
Published: February 2011

Abstract
The term vulcanization was restricted originally to the treatment of rubber by sulfur at elevated temperatures, the purpose of which was to overcome the faults of the raw material and in general to make it of more practical value. For more than a half century, sulfur and a few sulfur compounds were the only agents known to have this remarkable property, but later selenium, tellurium, and finally various oxidizing agents and sulfurizing agents as well were found to be capable of vulcanizing rubber. In all these transformations, the vulcanizing effect is the result of the direct or indirect action of one of the elements of the second group of metalloids. On the assumption that vulcanization involves the formation of bridges between linear molecules, it was decided to attempt to bring about this bridge formation by classic condensation reactions under such conditions that it would be certain that elements of the second group of metalloids would play no part in the reaction. The difficulty in uniting rubber hydrocarbon chains lies in their lack of reactivity, for their structure is of such a character that it is not easy to bring about a double linking reaction by condensation through an intermediate agent. It was attempted to overcome this difficulty by first adding active nuclei to the hydrocarbon chains. With this accomplished, it remained as a second step only to join together two active centers by a suitable chemical reagent; a process which should, if the scheme turned out to be correct, result in vulcanization.
The Magnetic Anisotropy of Rubber
Authors: Cotton-Feytis Eugenie 
Published: February 2011

Abstract
In experiments on the magnetic properties of some crystals, one of these cystals was suspended between the poles of a small electromagnet. These poles were flat and of the same diameter as the cores (5 cm.), while the air gap varied from 1.5 to 4 cm. and the field at the center from 8800 to 5500 gauss units. The crystal was suspended by a silk thread with very slight twist and a small rubber ring cut from a piece of gas tubing. It was observed that, as soon as the electric field was set up, the assembly oriented itself strongly, and the couple exceeded the magnitude which was expected. It was observed also that this couple continued when the crystal was removed and only the rubber ring remained as a possible cause of the phenomenon. The same phenomenon is observed with a ring of paramagnet rubber and with a ring of diamagnetic rubber, whether the rubber is supple or whether it has become brittle, and whether the ring is perfect or whether it has a cut in it. Instead of flat rings, longer sections of tubing, e.g., 2 to 3c m. long, can be suspended in the magnetic field. It is then particularly surprising to observe that the pieces of tubing always orient themselves axially in the magnetic field, whereas under the same conditions elongated isotropic substances orient themselves in this way only if they are paramagnetic.
The Structure of Polyisoprenes. I. The Crystal Structure of Geranylamine Hydrochloride
Authors: Jeffrey G. A. 
Published: February 2011

Abstract
An x-ray analysis employing three-dimensional Fourier syntheses has established the crystal structure and molecular dimensions of the diisoprene derivative, geranylamine hydrochloride. The molecules, which have a transconfiguration and are therefore analogous to gutta-percha, lie parallel and end-to-end in pairs within an ionic framework, where each nitrogen atom is equidistant from four chlorine neighbors. The two isoprene units are planar and have normal interatomic distances, but are linked by a C—C bond markedly shorter than a normal single bond. This unusual bond feature is accompanied by a coplanar arrangement with the adjacent carbon bonds.
A Study of Rubber-Sulfur Mixtures by Radiomicrography
Authors: Trillat Jean-Jacques 
Published: February 2011

Abstract
It is a recognized fact that the size of sulfur particles and their state of dispersion in a mass of rubber play an important role in the vulcanization process. In the work described in the present paper, an attempt was made to develop a simple method by which the incorporation of sulfur into rubber could be followed and controlled. As a means to this end, the method of transmission radiomicrography already described by the author was employed. Samples of rubber, previously mixed with various percentages of sulfur, were placed between two thin sheets of cellophane 0.06 mm. thick, and pressed out at a temperature of 50°–60° C until the total thickness of the samples (rubber + cellophane) was 0.18 mm. The films prepared in this way were placed in a photographic plate holder, with care to obtain perfect adhesion to the special Lippmann film used in this technique. The system was then exposed to radiation from a sealed tube with very sharp focus and with a copper anticathode, specially constructed to obtain this effect, and functioning under 8 kilovolts. Under these conditions the K rays of copper are not excited, and only radiation of the order of 2 A.U. acts on the system. The distance of the samples from the source of light was several centimeters ; the time of exposure was 2 to 3 minutes. The photographic negatives obtained were subsequently enlarged several tenfold and in some cases several hundredfold. The samples which were examined included rubber-sulfur mixtures containing 1, 5, 10 and 32 per cent, respectively, of sulfur. The first tests were carried out on the mixtures before they had been vulcanized. In the unvulcanized state the particles of sulfur were very clearly defined because of considerable absorption of the x-rays. By examination of the photographic negatives after enlargement, it was possible to determine the dispersion of the sulfur throughout the rubber, the uniformity of this dispersion, and the dimensions of the sulfur particles. It was possible also to construct a distribution curve, and to follow the influence of the time of mixing, both on the shape of the particles and their distribution. The same samples were examined after they had been vulcanized for various times at 143° C. In this way it was possible to determine both the effects of the sulfur content and of the time of vulcanization.