bluuebunny/crossref_metadata_2025_split huggingface dataset:
IV. The Micellar Theory of the Structure of Rubber
Authors: Gee G. 
Published: February 2011

Abstract
The molecular weight data reported in Part II depend on the assumption that the values obtained by extrapolating osmotic pressure measurements to infinite dilution represent true molecular weights. This point of view has been strongly criticized, particularly by Pummerer and his coworkers, according to whom rubber normally exists in solution in the form of micelles comprising more or less well-defined aggregates containing a considerable number of chemical molecules. The- osmotic “molecular weight” is then regarded as the weight of an average micelle. If they exist, these micelles may be important in determining both the chemical and physical behavior of rubber, for we should clearly expect the bonds by which the chemical molecules are bound into micelles to be weaker than those within the molecules. It may be noted that it has been shown elsewhere that the physical properties of a series of rubber fractions are closely related to their osmotic and viscosity molecular weights. Since, according to the micellar theory, these fractions can differ only in micelle size, their mechanical behavior must, from this viewpoint, be determined by the size of the micelles, which must therefore remain intact during mechanical deformation of the rubber. It is the object of the present paper to examine in more detail the basis of the micellar theory, and especially to offer an interpretation of the results of the East method, on which Pummerer's arguments are mainly based.
Phase Transition and Elastic Behavior of High Polymers
Authors: Mark H. 
Published: February 2011

Abstract
Present experimental knowledge indicates that linear or moderately branched and cross-linked high polymers are capable of undergoing two types of phase transitions. (1) A first-order transition, characterized by a sudden change of quantities such as specific volume, energy, and entropy, which may be briefly called a “crystallization” (or fusion). The crystallized areas formed in the course of this process are mostly elongated cylindrical or flat bundles of parallelized chainlike molecules, or segments of them, with an average length between 500 and 5000 A.U. and an average diameter of 50–200 A.U. They do not have plane and sharp boundaries, but they represent only regions of higher geometrical order and presumably go over gradually into the mesomorphous and amorphous parts, which approach the structure of a liquid. It seems that one and the same chain can extend through such a crystallite, enter an amorphous area, extend over into another crystallite, etc. Figure 1 is an idealized sketch of this situation. (2) A second-order transition, characterized by a sudden change of quantities such as heat capacity and thermal expansion, takes place at lower temperatures than fusion, and presumably indicates that below this transition point the individual segments of the chain molecules do not carry out rotational and vibrational movements as a whole, but do carry out such internal Brownian movements above this point. Hence, according to the ideas of Eyring, Kuhn and Meyer, they act as independent kinetic units of the system investigated. Figure 2 is an interpretation of this concept.
A Statistical Treatment of Crystallization Phenomena in High Polymers
Authors: Alfrey T. , Mark H. 
Published: February 2011

Abstract
An attempt has been made to explain the anomalous crystallization behavior of high polymeric materials on the basis of entropy changes in the amorphous material. The free energy of the amorphous phase depends not only on the temperature and pressure, but also on the degree of extension and the fraction of crystalline material in the sample. A crude model embodying these characteristics was proposed. On the basis of this model, it is possible to explain the unsharp melting point of rubber, the dependence of crystallization on the degree of extension, and the phenomenon of spontaneous extension.
Evaluation of the Buffer Capacity of Crude Rubbers
Authors: Newton E. B. , Willson E. A. 
Published: February 2011

Abstract
The hypothesis was advanced in the preceding paper that an important factor in determining the rate of cure of rubber is the acid-base equilibrium developed during vulcanization and that such an equilibrium is determined to a large extent by the nature and quantity of the latex serum substances remaining in the crude rubber mass. In effect, this serum material was regarded as a buffer substance. If this were true, it follows that differences in the buffer capacities of various crude rubbers should be demonstrable and, in the following discussion, two sets of experiments designed with this object in view are described.
Polysulfide Theory of Accelerator Action during Vulcanization. Evidence for the Theory
Authors: Morris Ross E. 
Published: February 2011

Abstract
On the basis of indirect experimental evidence, Scott and Bedford proposed about twenty years ago a mechanism of the accelerator action of metallic dithio-carbamates, known as the polysulfide theory. According to these authors, a metallic dithiocarbamate reacts with sulfur during vulcanization to form a polysulfide, which subsequently decomposes and liberates active sulfur for reaction with the rubber hydrocarbon. This theory gained support by the observation of Jones and Depew that the solubility of zinc dimethyldithiocarbamate in rubber is increased when sulfur is added to the mix, since such behavior may result from the formation of a soluble polysulfide. More recently, Scott and Sebrell questioned Scott and Bedford's polysulfide theory, on the basis that no polysulfides of metallic dithiocarbamates have been isolated. The author does not intend to enter into the controversial subject of the mode of action of vulcanization accelerators, but rather to present experimental data which confirms the original supposition of Scott and Bedford that sulfur forms unstable addition compounds, or polysulfides, with metallic dithiocarbamates. The metallic dithiocarbamates investigated were zinc diethyldithiocarbamate and zinc dibutyldithiocarbamate.
Effects of Low Temperatures on Neoprene Vulcanizates
Authors: Yerzley Felix L. , Fraser Donald F. 
Published: February 2011

Abstract
Realizing the need for general agreement throughout the rubber industry on the evaluation of the freeze-resistance of various elastomers, we have outlined several procedures and reported typical test results. Although the procedures described are inadequate as standard tests for complete evaluation, it is hoped that they may stimulate development of procedures which will be generally acceptable.
The Effect of Temperature on the Sunlight Deterioration of a Rubber Compound
Authors: Ball J. M. , Bradley C. E. 
Published: February 2011

Abstract
The subject of this article might be the question: “Does temperature have an effect on the deterioration of rubber in sunlight and, if so, approximately how much effect?” We are interested in any effect of temperature because rubber goods in service are frequently subjected to sunlight over a fairly wide temperature range. There are apparently very few references or comments in the literature on this subject; but we wish to look briefly at some significant experiments of the past which have to do with sunlight without regard for temperature, and then discuss a new experiment.
Colloidal Carbon as Revealed by the Electron Microscope
Authors: Wiegand William B. , Ladd William A. 
Published: February 2011

Abstract
The electron microscope of today may be said to rest on the pioneer work of three outstanding physicists. J. J. Thompson, in 1897, discovered electrons under the name of negative corpuscles. De Broglie, about 1922, established the wave characteristics of electrons. In 1926 Busch established the electron lens. In 1935, E. F. Burton, following a visit to Germany, envisaged the enormous potentialities of the electron microscope and began a program at Toronto designed to eliminate the serious defects of early German instruments. In 1938, this program culminated in the construction of a new and superior instrument by two of his graduate students, A. Prebus and J. Hillier. The publication of their results early in 1939 aroused the immediate interest of the Columbian Carbon Company which later established a Fellowship at Toronto under Professor Burton's direction. In 1940, A. Prebus, assisted by W. A. Ladd, working in Toronto, secured for Columbian the first perfect pictures of Micronex, from which accurate data as to mean surface area and as to particle shape were obtained. Public release followed in June, 1940. Prebus is now Professor at Ohio State University and is pursuing the theoretical side. Hillier is at R. C. A., where instruments, of essentially Toronto design, are being developed commercially, and Ladd has joined the Columbian Carbon Research Laboratories, for the two-fold purpose of further improving the microscope and of applying it to the problems of natural and synthetic rubber reënforcement. This work of Professor Burton and his pupils is of importance under present critical conditions since the replacement of natural by synthetic rubber necessitates a new approach to the theory and practice of rubber reënforcement. With the aid of the electron microscope, it is now for the first time possible to evaluate the role played by surface area in carbon-rubber reënforcement.
The Estimation of Small Percentages of Rubber in Fibrous Materials
Authors: Blow C. M. 
Published: February 2011

Abstract
Rubber is being used in increasing quantity in fibrous materials of all types as a binder or to impart particular and special properties. The percentage of rubber employed varies from 3 to 15 or 20 per cent, and it is becoming of interest and importance to, have analytical methods to estimate with some degree of accuracy the percentage present. This estimation has several difficulties, and no one method can be adopted on account of the difference in behavior of various fibres. The fibre may consist of protein, such as silk, wool and other animal fibre, leather, or cellulose, such as jute, cotton, rayon, paper, kapok, etc. The rubber may be vulcanized or unvulcanized, and partly or completely in the oxidized state. In addition, there may be organic material, such as protein, soap (added as stabilizer for the latex), fats, oils, waxes, dyestuffs and inorganic substances from the fibre, fillers and pigments, coagulants, and so forth—to name only a few possible compositions. The problem appears complex, but may be simplified in some cases by knowing, from the process of manufacture, the definite absence or presence of certain of these likely ingredients.
Static Electric Problems in Tires
Authors: Liska J. W. , Hanson E. E. 
Published: February 2011

Abstract
Since its advent about thirty years ago, the pneumatic tire has been remarkably improved to meet increasingly severe requirements. Improvements in motor vehicles, increased speed of travel and, in general, a more and more critical attitude on the part of the consumer, have introduced difficult problems for the rubber technologist. One of the more recent and unusual of these problems, introduced in part by the popularization of the automobile radio, has been the accumulation of static electrical charges on a moving car. At first difficulty was experienced mainly with radios in passenger cars. In some cases when the auto was stationary and the motor running, the program reception was clear and uninterrupted but, when the car was set in motion and driven for some distance, reception was seriously impaired by loud, intermittent static noises. Later, reports began to circulate of toll-bridge collectors receiving severe electrical shocks on touching any part of a car which had just pulled to a stop after a sustained drive. Similar phenomena reportedly took place when motorcycle police touched cars they had pursued and stopped. Recently, passengers on commercial busses, especially on those operating in hot, dry regions, have experienced electrical shocks on entering or leaving. The object of this paper is to describe some of the methods employed in measuring, and some of the means developed for controlling, the observed effects.
Structure of the Butadiene-Styrene Copolymer
Authors: Alekseeva E. N. , Belitzkaya R. M. 
Published: February 2011

Abstract
The experimental data indicate that joint polymerization of styrene and butadiene results in copolymers of varied structure. Of the styrene, 31.2 per cent forms, with the butadiene, macromolecules in which the two components alternate regularly, whereby the butadiene combines in its 1,4-position. Forty per cent of the styrene forms macromolecules, in which two units of styrene interlink adjacently. Such “styrene pairs” are separated by one or more molecules of butadiene polymerizing in their 1,4-position. The remaining 29 per cent of styrene evidently enters into the composition of branched macromolecules, formed as the result of butadiene linking both in the 1,2- and in the 1,4-positions. Taking into consideration the fact that formic acid must have been formed from macromolecules, with butadiene linked in the 1,2-position, we can conclude that 23.3 per cent of the butadiene polymerized in its 1,2-position, and the rest in the 1,4-configuration.
The Long Spacing in Rubber
Authors: Schallamach Adolf 
Published: February 2011

Abstract
The x-ray diagrams of some rubbers give a long spacing, which was first reported by Clark and collaborators. According to them, it is found only in gel rubber, where it has the value of 54 a.u., but it is absent in sol rubber. This spacing is oriented in stretched rubber, the x-ray reflections contracting into two spots in the equatorial plane. This means that the long spacings lie in planes at right angles to the fibre axis. As we found it difficult to account for this result and, furthermore, had indications that this long spacing might depend on the nature of the rubber, we examined a number of specimens of different origin and preparation. We used a camera of about 10-inch radius, reducing the air scattering by inserting an evacuated length of wide tube with thin cellophane windows at both ends. The x-ray source in these experiments was the 50 kw. x-ray generator of this laboratory, working with an input of 30 to 40 kw.
An Elastic Theory for Rubber
Authors: Latshaw Elmer 
Published: February 2011

Abstract
The elastic properties of vulcanized rubber present a difficult problem to generalize, mainly because of the large number of compounds in common use. There are good reasons for many kinds and grades, and a characteristic common to all is large elastic strain. Even in the best grades of rubber these strains are not perfectly elastic, but this is also true of almost all other materials, including spring steels. An elastic strain theory will be derived for a specific group of rubber compounds, namely, spring stocks. These are dense, strong rubbers, highly elastic within the working stress range, and capable of supporting loads under continuous vibration and shocks. To be of real value, the strain law should closely predict strain for the range of working stress, or more generally for the elastic range, and should indicate the trend at very high stresses where inelasticity becomes more prominent. Figure 1 shows a cylindrical element of rubber having an area A0 and length h when unstressed. If a uniform stress is imposed perpendicular to the end area, the length changes to H and the area to A. These symbols apply whether the stress is tension or compression. The usual definition of strain, i.e., change in length due to stress divided by the unstressed length, is comprehensive and descriptive for the large strains in rubber.
The Plastic-Elastic behavior of Ebonite
Authors: Scott J. R. 
Published: February 2011

Abstract
A hypothesis is put forward to explain the plastic-elastic behavior of ebonite and its dependence on temperature. This is based on the previously described mechanical conception of ebonite as a system comprising a heat-stable elastic phase and a viscous temperature-sensitive phase, but the difficulty of reconciling this two-phase concept with the probable structure of ebonite is avoided by replacing the elastic and viscous phases respectively by primary and secondary (cohesional) bonds, the relaxation of the latter, due to their relatively low temperature-stability, being responsible for all time effects in the deformation of ebonite. The hypothesis explains the main facts relating to so-called plastic yield and to the residual strain after recovery from deformation, and thus appears to form a useful basis for further research on ebonite.
Rubber Photogels
Authors: Naunton W. J. S. 
Published: February 2011

Abstract
1. The conditions of photogel formation and reversion in rubber solutions have been studied. The larger the rubber molecule the more readily is gel formation effected. 2. Photogels exhibit all the properties associated with cross-linked molecules. 3. Photogels made with most synthetic rubbers are not influenced to the same extent by the presence of oxygen, and do not revert on further exposure in the presence of oxygen. 4. The suggestion is made that gel formation is due to oxygen-bridging of already oxygenated centers. This bridging is not possible in the presence of oxygen, since further oxidation results, with cleavage of the molecule. In the case of active solvents, bridging may be due primarily to condensation with solvent. Bridging is also probably accompanied by a limited degree of cyclization.
Dielectric Constant, Power Factor, and Conductivity of the System Rubber-Calcium Carbonate
Authors: Scott Arnold H. , McPherson Archibald T. 
Published: February 2011

Abstract
The results obtained in this investigation indicate that either the formula developed by Wiener (Formula 7) or the exponent formula (Formula 9) may be used for the computation of the dielectric constants of mixtures of calcium carbonate and rubber. Formula 7 may be preferred, since it gives some indication of the shape of the particles and state of dispersion of the powder. There was little difference between values of the dielectric constant and loss tangent at 1 kilocycle per second and at 100 kilocycles per second. The change of the loss tangent with the content of calcium carbonate was not large, but a direct relationship between loss tangent and percentage of calcium carbonate was indicated. The 1-minute-conductivity values increased continuously with increasing content of calcium carbonate when Vistanex was used as the base, but passed through a minimum when natural rubber was used.
Application of Rubber Latex to Woolen Hosiery
Authors: Piper G. H. 
Published: February 2011

Abstract
The application of rubber to textiles has made great progress within the last ten years, and the introduction of rubber latex with its high resistance to aging, which is of great importance where textile apparel is worn next to the skin, has virtually opened up a new field. The sock has not altered greatly, and its greatest defect, the formation of holes at the toe and heel areas still remains. It was with the object of reinforcing these areas by impregnation with rubber latex that this research was commenced, resulting in the present process. Briefly, the process is the application to the knitted sock, at the areas to be reinforced, of a rubber latex containing specified amounts of wetting and stabilizing agents so that the latex coagulates after penetration into the wool to a limited extent. The process is essentially an impregnation process, and the meshes between the threads remain open and free from rubber. The resulting hosiery is comfortable, and shows great resistance to the formation of holes. In the development of the process, which occupied several years, numerous difficulties were encountered, not the least being the severe conditions to which the rubber is exposed. The warmth of the body, perspiration, laundry treatment and other factors necessitated a latex compounded to give high resistance to aging.
Dunlop Fatigue Test for Rubber Compounds
Authors: Gough V. E. , Parkinson D. 
Published: February 2011

Abstract
This paper considers the effects produced inside a block of rubber subjected to repeated cycles of stress. Other types of fatigue, such as flex cracking or the phenomenon recently referred to by Cadwell, Merrill, Sloman and Yost as static fatigue, are not discussed. The fatigue test which will be described in the following pages has been used for a number of years in the Dunlop Rubber Company's laboratories. The test machine, like others which have been described by Martens, Vogt, Abbott, Depew and Snyder, Cooper, Havenhill and Macbride, Havenhill, Lessig, and Roelig, can be used for assessing heat development, the failure produced in the test-piece being then of the “blow-out” type, or it can be used to produce breakdown in specimens which have been stressed for prolonged periods at a moderately high, although steady temperature. The failure may then be considered to be one of fatigue and not one of thermal decomposition, although, as will be shown, the heating effect is one of the most important factors operating to produce failure. Among the test machines referred to above, the one described by Depew and Snyder is similar to the Dunlop machine, an early form of which was already in use for the purpose of evaluating heat generation in solid tire compounds when Depew and Snyder's paper was published in 1929. The present improved machine and technique are the result of several years of subsequent development work. The stressing conditions of the machine, which produce direct compression, are as simple as possible and give results which vary less and are more easily interpreted than those obtained when they are more complex, as, for example, when they introduce shear in addition to compression.
Vulcanization of Buna-S (GR-S) with Organic Sulfur Compounds. II.
Authors: Throdahl M. C. , Beaver D. J. 
Published: February 2011

Abstract
Buna-S (GR-S) was vulcanized with acid, thiocyanic, amine, thiuram and phenolic sulfides. Heat embrittlement and resistance to cut-growth of the vulcanizates obtained with most of these compounds were better than those exhibited by normal stocks containing free sulfur, but heat generation was higher.
Effect of Accelerators on the Heat Embrittlement of GR-S Vulcanizates
Authors: Hunter J. S. 
Published: February 2011

Abstract
Two of the most serious shortcomings of GR-S type synthetic rubber are its poor resilience, leading to excessive heat build-up under severe stress cycles, and its property of hardening during exposure to heat in service. Heat embrittlement aggravates heat build-up and vice-versa, so a vicious circle develops which eventually leads to failure. The problem of minimizing heat embrittlement has received considerable attention, and much work on the subject has been published. Some of this published work is reviewed briefly below, and an account is given of certain experiments carried out in this laboratory. The results of these experiments enable some preliminary conclusions to be drawn on one aspect of the problem, namely, the effect of accelerators on the heat embrittlement of GR-S.