bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gasoline Diffusion Resistance of Thiokol Type F
Authors: Martin S. M. 
Published: February 2011

Abstract
The solvent-resistant properties and low swelling characteristics of Thiokol synthetic rubbers are well known to the rubber technologist. It is also known that these rubbers are highly resistant to permeation by solvents. Gasoline and blends of gasoline and benzene do not diffuse into and through them to any great extent. The permeation of rubber and synthetic rubbers by fixed gases, such as hydrogen and helium, has been the subject of considerable study. Such information has a bearing on the construction of dirigibles, blimps, observation balloons, and barrage balloons. Sager shows that the ratio of permeability to hydrogen for Thiokol Type DX (now Type F), compared to rubber at 25° F, is 1 to 12. Recently the diffusion of gasoline and oil through solvent-resisting synthetic rubbers has become of general interest. The information generally sought is the amount of gasoline that diffuses through a given area in a given time.
Rise of Temperature on Fast Stretching of Synthetics and Natural Rubbers
Authors: Dart S. L. , Anthony R. L. , Guth Eugene 
Published: February 2011

Abstract
This investigation covered more types of rubber and rubberlike synthetics than were studied by previous investigators. From the results it seems apparent that at least a part of the disagreement between previous workers on this subject is due to the different types of rubber employed. It is also important to note that the temperature changes observed were of the order predicted by sensory observation.
The Course of Autoöxidation Reactions in Polyisoprenes and Allied Compounds. I. The Structure and Reactive Tendencies of the Peroxides of Simple Olefins
Authors: Farmer Ernest Harold , Sundralingam Alvappillai 
Published: February 2011

Abstract
The structural changes which occur in olefinic substances when they undergo oxidation by molecular oxygen have never been elucidated, although many of these changes, such as the autoöxidation of drying oils and of rubber, are of enormous practical importance.
Processing Characteristics of Synthetic Tire Rubber
Authors: Garvey B. S. , Whitlock M. H. , Freese J. A. 
Published: February 2011

Abstract
The processing characteristics of synthetic tire rubber, such as is being made in the government program, are sufficiently different from those of natural rubber to require different laboratory and factory treatment. Since the laboratory tests used for the evaluation of processing characteristics were developed for natural rubber, it is not surprising that they are not so satisfactory for synthetic rubber. The purpose of this paper is to discuss some of the characteristics of synthetic tire rubber, and to describe certain tests which have been found useful for evaluating different types of synthetic rubber or different compounds of the same synthetic rubber. In the course of the development, it has been necessary to evaluate rubbers with a wide variety of processing properties. As production has increased, there has been less variation in the output from any one plant. As the newer and larger plants come into full production, we can expect greater uniformity from each plant and between different plants. We can also look forward to gradual improvements in processing characteristics. This development will be ensured by adequate laboratory methods for evaluating processing properties. This discussion is based in part on variations encountered in development work and in part on the properties of the present production from one plant.
Density Measurements on Synthetic Rubbers
Authors: Wood Lawrence A. , Bekkedahl Norman , Roth Frank L. 
Published: February 2011

Abstract
For many purposes the density of a material need be known with an accuracy of only a few per cent. For many materials the density of one sample may differ from that of another by this amount, and no useful purpose may be served by making more precise measurements on individual samples. In natural rubber, the densities of different samples have been shown, in a compilation of twenty-one values, to lie with two exceptions between 0.905 and 0.919 gram per cc. at 25° C. The variations probably represent real differences in the samples and not accidental errors of observation. Since one can seldom know exactly the origin and subsequent treatment of a sample of natural rubber, there is little value in increasing the precision of measurement. Synthetic rubbers, on the other hand, can be regarded as usually produced under conditions which are much better controlled and known. It is logical, then, to measure the density with greater precision and to hope to be able to ascribe significance to its variations from one sample to another. The present work is concerned with the development of a method for preparing specimens of synthetic rubber in a form suitable for precise measurements of the density, the actual measurement by the method of hydrostatic weighings, and a presentation of the results for most of the varieties of synthetic rubber now of commercial importance in the United States.
Viscosity and Cryoscopic Data on Polystyrene. Discussion of Staudinger's Viscosity Rule
Authors: Kemp A. R. , Peters H. 
Published: February 2011

Abstract
1. The cryoscopic method is not satisfactory for polystyrenes containing more than twelve styrene units in the chain on account of the failure of their solutions to obey Raoult's law. 2. The present work has established a new Kcm value of 0.45×104 for benzene solutions of polystyrene to be used in the equation: A Kcm value of 0.6×104 has been similarly established for benzene solutions of polyindene. 3. Increased confidence in the viscosity-molecular weight procedure is derived from the data presented for the new Kcm equivalent covering a wide range of different polymers.
The Interaction between Rubber and Liquids. 1. A Thermodynamical Study of the System Rubber-Benzene
Authors: Gee G. , Treloar L. R. G. 
Published: February 2011

Abstract
Equations are developed relating the thermodynamic properties of a mixture of rubber + liquid with the vapor pressure of the liquid above the mixture. Experimental methods are described for the determination of vapor pressure over the whole range of composition of the mixture. By the use of four different methods, it was possible to measure relative vapor pressure lowerings Apo/po° from 2×10−6 to 0.997. Complete vapor pressure data are given for rubber-benzene mixtures at 25° C, together with the calculated Gibbs' free energies of dilution and solution. Temperature coefficient measurements at a number of concentrations are employed to calculate heats of dilution, and these are interpplated by a modified form of an equation due to Langmuir. In this way the heats of dilution and solution are also obtained over the whole range of composition. Combining the heat and free energy data gives the entropies of dilution and solution. The entropy of dilution is approximately twice the heat of dilution over a wide concentration range and, except in dilute solutions (&lt; 5% rubber), both are independent of the molecular weight of the rubber. The entropy of dilution is very much larger than its ideal value, and can be approximately represented by an equation of Flory, though there are significant discrepancies in the region of dilute solutions. The molar heat of solution of rubber is so large that the miscibility of rubber and benzene can be explained only by the anomalously large entropy of solution.
The Bacterial Oxidation of Rubber
Authors: ZoBell Claude E. , Grant Carroll W. 
Published: February 2011

Abstract
In studying the biological oxygen demand of sea water, it has been observed that rubber stoppers increase the amount of oxygen consumed. In fact, the small amount of rubber gasket exposed to the water in citrate of magnesia bottles perceptibly increases the amount of oxygen consumed after 5 to 10 days' incubation. Heat-sterilized as well as formaldehyde-preserved controls proved that the increased oxygen consumption is attributable to biological activity. One-gram samples of various kinds of rubber, cut in small pieces to give a surface area of approximately 10 sq. cm., were placed in 160-cc. glass-stoppered bottles. After sterilizing in an autoclave at 120° C for 20 minutes, the bottles were filled with sterile water saturated with oxygen. Half the bottles were inoculated; the others were left sterile. Duplicate bottles were analyzed for oxygen immediately by the Winkler technique, and the others were incubated in the water bath for one to five days at 22° C, after which the amount of oxygen consumed was determined. It was necessary to decant or siphon the water from the rubber before treating it with the Winkler reagents because free iodine reacts with rubber.
Natural Aging of Reclaimed Rubber
Authors: Palmer Henry F. , Crossley Robert H. 
Published: February 2011

Abstract
As reclaimed rubber undergoes natural aging, it becomes less tacky and more resistant to breakdown during milling. This appears to be true to a lesser degree for reclaims having a high alkalinity than for those with low alkalinity. The acetone extract of reclaimed rubber remains constant as it ages, but its chloroform extract tends to decrease. These changes are accompanied by only small variations in physical properties, as shown by results obtained in typical test formulas. There is no significant change in quality when reclaim up to 18 months of age is used. This was true also of tire treads containing reclaim aged 15 months, as judged by actual road tests.
Accelerators and Colors in Sponge Rubber
Authors: Watts John T. 
Published: February 2011

Abstract
The class of products falling under the generic name of sponge rubber may be subdivided into two main sections, depending solely on whether the pores are closed or open. Closed pore structures, in which the gas cells retain their individuality, are characterized by cell size and hardness of the vulcanizate. This latter may vary from the softness of toilet-sponge to the hardness of ebonite. Among the softer grades of closed pore sponge, some of the contributing factors to softness of texture are: (1) the method and degree of plasticizing the raw rubber, (2) the ratio between raw rubber, fillers and softeners, and (3) the type of accelerator used. Open-pore structures include latex sponge and cellular rubber in which the gas cells have been ruptured by mechanical means after curing. For the purpose of this paper the position is simplified by considering latex sponge alone as an open-pore sponge, as the mechanical operation for the production of open-pore from closed-pore sponge follows the rubber manufacturing process. The closed-pore structure in rubber is usually produced by compounding with gas- or vapor-producing materials which, with change in temperature during cure, either liberate gas or change in phase to produce individual cells in the rubber compound. Alternatively, gas (usually nitrogen or carbon dioxide) may be dissolved in the rubber compound under pressure and the stock inflated by either rise in temperature or decrease in pressure, or both.
The Crystal Structure of β-Isoprene Sulfone
Authors: Cox E. G. , Jeffrey G. A. 
Published: February 2011

Abstract
A detailed x-ray analysis has shown that the molecule of β-isoprene sulfone has a heterocyclic structure, in which resonance occurs between the three carbon-carbon bonds of the C4S ring. The bond lengths are C—C (in the ring) 1.41 a., C (ring)—C (methyl) 1.54 a., C—S 1.75 a., and S—O 1.44 a., all ± 0.02 a.; the distribution of the four sulfur bonds is approximately tetrahedal.
Molecular Weights and Intrinsic Viscosities of Polyisobutylenes
Authors: Flory Paul J. 
Published: February 2011

Abstract
Experimental methods for fractionating polyisobutylene and for determining osmotic pressures have been described. The ratio π/c of osmotic pressure to concentration has been found in the case of cyclohexane solutions of polyisobutylene to vary nonlinearly with concentration, contrary to recent theories advanced by Huggins and the writer. The slope of this relationship appears to be independent of molecular weight. Reliable methods for extrapolating π/c to c=0 have been established, enabling the determination of absolute molecular weights with satisfactory precision up to values of about 1,000,000. Molecular weights of polyisobutylenes calculated from Staudinger's equation are too low; the discrepancy is more than ten-fold at high molecular weights. On the basis of data for carefully fractionated samples covering a two-hundred-fold molecular weight range, the intrinsic viscosity is found to be proportional to the 0.64 power of the molecular weight. This decided deviation from Staudinger's “law”cannot in this instance be attributed to nonlinear chain structure, as Staudinger has sought to do in other cases. This dependence of molecular weight on intrinsic viscosity leads to the definition of a “viscosity average”molecular weight which is obtained when the relationship is applied to heterogeneous polymers. The viscosity average is less than the weight average molecular weight, which would be obtained if Staudinger's equation were applicable, and greater than the number average obtained by osmotic or cryoscopic methods.
Synthetic Rubber. A Spectroscopic Method for Analysis and Control
Authors: Barnes R. Bowling , Liddel Urner , Williams V. Z. 
Published: February 2011

Abstract
Rapid quantitative analysis of compounds of prime interest in the production of synthetic rubber is possible by a relatively simple technique of spectroscopy. An apparatus suitable for such analyses is described, which does not require skilled technicians. It may be easily converted into an automatic control device for the control of production. The spectra of the natural and synthetic rubbers illustrated provide information concerning the structure of rubber molecules and can be used to identify the type of rubber present in unknown samples.
Identification of Carbon Black by Surface-Area Measurements
Authors: Amon F. H. , Smith W. R. , Thornhill F. S. 
Published: February 2011

Abstract
In general then, we may conclude that carbon black can be recovered from rubber stocks with unchanged surface-area. The nitric acid technique is the most effective method of effecting the separation. The digestion temperature must be controlled to between 60° and 70° C, for a total of not more than 3 to, 4 hours. This method of identifying the carbon black in an unknown rubber stock is directly applicable only in the presence of a single type of carbon black. If blends of blacks are employed in the material under investigation, some secondary identification is also required. The nonimpingement-type blacks, for example, are readily identified by microscopic observation. From the known surface-areas of these materials and the total per cent carbon present in the stock, a fairly positive identification of the blend can be made. The fact that carbon black can be recovered quantitatively and with unchanged surface-area from vulcanized rubber stocks appears to lend impetus to a physical concept of carbon black reinforcement. This point of view implies that any chemical combination between the ingredients of the rubber stock and the carbon black would be evidenced by some alteration in the surface of the latter. A few experiments were performed in an attempt to establish to what extent this concept was valid. One hundred grams of Grade-6 carbon black were intimately mixed with 6.6 grams of sulfur. This is about the ratio in which they are present in a standard rubber batch. Samples of this mixture were subjected to the standard curing temperature of 134° C for 30, 60, and 90 minutes. The free sulfur was then extracted for 40 hours with acetone ,and the combined sulfur on the carbon was determined. Values of 0.16, 0.21, and 0.4 per cent combined sulfur were obtained. The original sample of Grade-6 carbon black had a surface-area of 108 square meters per gram. The extracted sample of black containing 0.4 per cent of combined sulfur had a surface-area of 109 square meters per gram. These values are identical within experimental error. While unaltered surface-area need not necessarily be interpreted as evidence of complete lack of surface reactions, it is the authors' opinion that the extent of chemical combination at the carbon black surface is very small. This interpretation is in accord with the views expressed in a previous publication3, where it was suggested that the chief role of carbon black in rubber reinforcement may rest on its ability to orient the chains of rubber molecules and thus alter the extent and type of rubber-sulfur bonds normally formed in non-reinforced rubber stocks.
Electrical Properties of Neoprene
Authors: Yerzley Felix L. 
Published: February 2011

Abstract
This review is based on data selected from tests conducted over a period of years. Under the circumstances it does not happen that identical Neoprene was used throughout. Several types are referred to in the compounds. Each group of tests is consistent within itself, but direct comparison from group to group is not justified. Neither do exact values within a group have individual merit, but the trends of electrical quantities with controlled changes of the variable under study are of primary importance. In general, numerical values reported are the average of results obtained on two samples, but all conclusions have been confirmed by numerous parallel and related tests. Unless otherwise specified, tests were made at 82° F, after the samples had been dried in a desiccator for at least 16 hours. Conventional methods were used. For all tests except those on dielectric strength, tinfoil electrodes 0.001 inch thick, adhered to the test slab by a thin film of petrolatum, were utilized. The test-specimens were usually 6 × 6 × 0.075 inch, except for occasional samples which were approximately 0.020 inch thick. In the case, of the direct-current resistivity test, the upper electrode was a 3-inch-diameter disk of tinfoil surrounded by a guard ring. The lower electrode was a 6-inch square of tinfoil. The Leeds & Northrup test set consisted of a sensitive galvanometer and an Ayrton shunt. An alternating-current bridge was used for measurements of conducting stocks. For the tests of power factor and dielectric constant, the upper electrode was a 3-inch-diameter disk of tinfoil, without a guard ring. The lower electrode was a 6-inch square of tinfoil. General radio equipment was utilized, consisting of a type-716A capacitance bridge, complete with the necessary auxiliaries. A telephone headset was used for detection of null points. All tests reported here were conducted at frequencies of 1000 cycles per second. For the determination of dielectric strength, an American Transformer Public Utility test set, type-TS, having a secondary voltage range from 100 to 50,000 volts was used. The electrodes were of the standard A.S.T.M. type. Ordinarily the test-specimens were about 0.020 inch thick and 6 inches square. The voltage across the electrodes was gradually increased until breakdown occurred. The gauge was then measured adjacent to the punctured spot, and the voltage and dielectric strength were calculated by dividing the value of the voltage by this gauge.
The Course of Autoöxidation Reactions in Polyisoprenes and Allied Compounds. Part. VI. The Peroxidation of Rubber
Authors: Farmer Ernest Harold , Sundralingam Alvapillai 
Published: February 2011

Abstract
Peroxides have repeatedly been shown to appear during the slow oxidation (perishing) of rubber in air, and during both its milling in air and the passage of air or oxygen through its solutions: yet in none of the recorded experiments has the production of any very substantial proportion of peroxide been demonstrated. This arises largely because, under many conditions of autoöxidation, no very considerable proportion of peroxide is present in the oxidation product at any stage, but in part because no convenient and reasonably accurate method of determining the peroxide content in so insoluble a substance as rubber has been available. It must inevitably happen in a long-chain molecule of polymer-homologous type containing on the average about 5,000 autoxidisable olefinic units that the progressive entrance of a heterogeneous element will yield a large variety of closely similar products if attack is fairly evenly distributed over the chain, but when, as in the case of oxygen, the heterogeneous element enters the hydrocarbon as a diatomic molecule, the atoms in which can ultimately separate and become attached to the carbon chain in a variety of ways, and causes, as the result of its progressive incorporation, scission of the chain at an ever-increasing number of the olefinic units, then the potential range of diversity of the products becomes enormously increased.
Interaction between Rubber and Liquids. IV. Factors Governing the Absorption of Oil by Rubber
Authors: Gee G. 
Published: February 2011

Abstract
A piece of vulcanized rubber, dropped into benzene, swells to several times its size but retains its shape. With raw rubber, a further stage ensues, in which the rubber flows and ultimately disperses. Inevitably, one tends to form a picture of the rubber attracting and holding the liquid with some strong force. It is the purpose of this paper to explain why this picture is believed to be entirely false, and to give an alternative explanation of the phenomena of swelling and solution. It will be necessary first to consider briefly the way in which simpler materials mix with one another. The simplest possible system is that of two gases which do not react with each other. In a gas the molecules spend most of their time a long way from one another, and the total energy of the system is therefore made up largely of the kinetic energy of thermal motion. As a consequence of this kinetic energy the gas molecules tend, on the average, to distribute themselves uniformly, so that any pair of gases mix completely. A quantitative interpretation can be given to this mixing tendency, in terms of the concept of entropy. Of the various ways in which entropy may be regarded, the most useful for the present purpose is in terms of probability. Qualitatively it is evident that gas molecules in violent thermal agitation are extremely unlikely to arrange themselves so all molecules of one type are confined to one part of the vessel. This is expressed in thermodynamic language by saying that the entropy of such an arrangement would be small. The second law of thermodynamics states that if, as in a gas, there is no change of energy, a system tends to take up the state of maximum entropy, or maximum randomness. A quantitative expression to the relationship between the entropy S and probability W, takes the form:
How Sulfur is Combined in Vulcanized Rubber
Authors: Van Amerongen G. J. , Houwink R. 
Published: February 2011

Abstract
Little is known with any degree of certainty about the way in which sulfur combines with rubber during vulcanization. It is the aim of the present work to examine, with the aid of Stuart molecular models, the various chemical reactions which have been suggested to explain the mechanism of vulcanization, and to decide which of these reactions may actually take place. THE MECHANISM OF THE REACTION BETWEEN RUBBER AND SULFUR Fundamentally, two general types of combination of rubber with sulfur are possible: (1) the formation of intermolecular sulfur bridges between chains of rubber molecules, with resulting formation of a network structure. (2) an intramolecular combination of sulfur with the individual chain molecules of rubber.