bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress-Strain Relation of Pure-Gum Rubber Vulcanizates in Compression and Tension
Authors: Wood Lawrence A. 
Published: February 2011

Abstract
The empirical function of Martin, Roth, and Stiehler represented by Eq. (1) where A has the value of 0.38 may be regarded as an adequate representation of the available experimental data covering both the compression and tension of pure-gum vulcanizates. The stress and strain are to be measured after a constant time of creep. The approximate validity extends over the range 0.5&lt;L&lt;3.5. The success of the single empirical function in representing data obtained in both compression and tension over a range as great as this is regarded as very significant. In the range of values of L from 0.5 to 1.0 (compression) the empirical function gives results in agreement with the predictions of the statistical theory of rubber elasticity. After representing the stress and strain in a transition region extending from L=1.0 to 1.5, the empirical function gives approximately constant coefficients C1and C2 in the Mooney equation over the range from 1.5 to about 3.5. The behavior of the empirical function in the transition region from L=1.0 to L=1.5 shows that the statistical theory of elasticity fails to represent the experimental data even at the lowest elongations while proving satisfactory in the compression region. The Mooney-Rivlin equation also fails to furnish adequate representation of the experimental data at low elongations. The most satisfactory method of determining Young's modulus from experimental observations of stress and strain in pure-gum vulcanizates involves a plot of log F/(L−1−L−2) against (L−L−1). For observations within the range of L=0.75 to 2.0 the simpler plot of F/(L−1−L−2) against (L - 1) is thoroughly satisfactory. In both cases M is obtained from the intercept, and the constant A in Eq. (1) is determined from the slope.
Redox Systems in the Initiation of Radical Processes. Mechanism of Action
Authors: Dolgoplosk B. A. , Tinyakova E. I. 
Published: February 2011

Abstract
The following redox systems capable of initiating radical polymerizations are discussed: (1) Systems of the first type, where the reaction leads to the formation of a single radical: (a) Mechanism of action of reversible systems involving dienols and salts of metals of variable valency. (b) Mechanism of the decomposition of hydroperoxides by the action of salts of metals of variable valency in their higher oxidation states. (2) Systems of the second type, where the reaction leads to the formation of two radicals. Mechanism of action and effectiveness of systems involving hydroperoxides, quinol, and sulfite. (3) Systems of the third type, in which the formation of free radicals is not directly linked to the redox process. Mechanism of action of systems involving diazoamino compounds and “polyamine” systems. (4) Crosslinking of unsaturated polymers at low temperatures by the action of redox systems. Transition from crosslinking to destructive processes in presence of oxygen.
The Reaction of Ozone with Rubber
Authors: Tucker Harold 
Published: February 2011

Abstract
The reaction of ozone with an unsaturated elastomer is very rapid until the double bonds at the surface have reacted. Only then do the double bonds beneath the surface become available for reaction with ozone. In this respect, unstressed rubber is similar to the metals that are protected from oxidation by a film of oxide formed on the surface. When this protective film is broken and fresh surface is exposed, the reaction can continue. This is the situation that exists when the rubber is under strain. Since the entire rubber surface can be considered as under a uniform bombardment by ozone molecules, to consider cracks in stressed rubber as arising from a directed chain scission process seems unrealistic. On the assumption that the double bonds in the rubber surface are equally reactive, and that ozone does not act as a pair of chemical shears snipping double bonds at right angles to the strain, crack development must then arise from the fact that the stress-strain characteristics of the rubber-ozone reaction product are not indentical to those of the original material and that ultimate elongation decreases continuously with increasing reaction with ozone. That such a mechanism would produce the type of cracks produced by ozone reacting with rubber can be shown by modifying the nature of the surface by vulcanization.
Effect of Degree of Elongation on Ozone Cracking of Rubbers
Authors: Zuev Yu S. , Pravednikova S. I. 
Published: February 2011

Abstract
It is known from the literature that there exists a socalled critical elongation at which disruption of the structure of rubbers under the influence of ozone is most severe. However, the available data concerning this problem are fairly contradictory. According to a number of statements the critical elongation is observed in the case of vulcanizates of natural rubber, but its estimation by different authors varies from 5 to 50%. Some authors consider that a critical elongation exists in the case of synthetic rubbers susceptible to attack by ozone, while others consider that no such characteristic exists. It is said that polychloroprene and butyl rubber do not possess this characteristic. However, none of these data can be regarded as reliable since in most cases ozone cracking of the rubbers was characterized by arbitrary methods, as a rule by the “degree of cracking” expressed by the number of marks. We have carried out a detailed investigation of the effect of the degree of elongation on ozone cracking of rubbers, the rate of growth of cracks being determined by an objective method based on the effective depth of the cracks calculated from the decrease of stress in the relaxed rubber sample when exposed to the action of ozone. The following rubbers—NK, SKS, neurite, SKN, and SKB were investigated in standard formulas, at optimum true tensile strength. Gutta-percha (elastic vulcanizate) and butyl rubber compositions in phr were: gutta-percha 100, MBT 0.8, sulfur 5; butyl rubber 100, stearine 3, MBT 0.65, thiuram disulfide 1.3, zinc oxide 5, sulfur 2.
Cis-Polybutadiene-Natural Rubber Blends
Authors: Railsback H. E. , Cooper W. T. , Stumpe N. A. 
Published: February 2011

Abstract
The preparation of 1:1 cis-polybutadiene-natural rubber blends has been shown to be feasible on a laboratory scale. Blends of this type have displayed hysteresis properties equivalent to the natural rubber control and have exhibited satisfactory modulus, tensile and Shore hardness in the recipes developed. Tests on retread passenger tires have confirmed the excellent service performance indicated for blends of this type compared to natural rubber by giving outstanding abrasion resistance and better resistance to cracking. The compatibility and acceptable processing characteristics of cis-polybutadiene-natural rubber blends have been confirmed by factory mixing. Based on the results to date it appears that 1:1 blends of cis-polybutadiene and natural rubber should be significantly better than natural rubber alone for heavy duty truck tire treads. Road testing of 10:00 inch × 20 inch truck tires is now in progress. If the outstanding performace of the blends is confirmed, the utilization of cis-polybutadiene rubber in truck tires could materially lessen the dependence of the rubber industry on natural rubber.
The Work of Rubber Elongation
Authors: Kusov A. B. 
Published: February 2011

Abstract
1. Curves of the relation between work of deformation and elongation in a vulcanizate are characterized by the absence of an inflection point. Regardless of the type of rubber, the compounding of the stock and the conditions of its preparation, they possess the property of being congruent when superimposed on one another. Because of this property the curves may be considered as parts of some composite curve which reflects the general properties of all vulcanizates. 2. Each of the curves of work vs elongation (and the rubber sample corresponding to it) may be characterized by a coefficient indicating the degree of displacement relative to the comparison sample. One may assume that this property of the curves of the work of deformation vs elongation has a certain physical significance. 3. There is a regular relation between the stress corresponding to the inflection point on the curves of stress vs elongation, and the curves of work vs elongation.
Adhesion Effects in Bonding Rubber to Metal by Leukonat Adhesive
Authors: Medvedeva A. M. , Deryagin B. V. , Zherebkov S. K. 
Published: February 2011

Abstract
1. In bonding of rubber to metal by Leukonat adhesive, the type of filler present in the rubber has a very great influence on the rubber-metal bond strength. 2. Active fillers of the gas channel black type in the rubber mixture increase the interaction of the rubber with the adhesive film. 3. Inactive fillers of the thermal black type have little influence on the interaction of the rubber with the adhesive film. 4. The results of the experiments suggest that Leukonat interacts chemically with active fillers present in the rubber during the bonding process. 5. The following empirical rule is formulated: high rubber-metal bond strength is obtained if the interaction of the adhesive film with the rubber is approximately of the same degree as with the metal. This rule is supported by the experimental data. 6. Sandblasting of the metal surface increases the true contact area by a factor of 1.5\2-2, while the bond strength is increased 20 to 100 times; this indicates that qualitative changes occur in the surface on sandblasting and that the nature of the metal-adhesive interaction is greatly changed in the process. It is difficult to explain this other than on the assumption that the charge of the double layer at the metal-adhesive boundary is increased, and in consequence the work of separation of this layer at the boundary is greater.
New Absolute Molecular Weight Method—Linear High Polymers
Authors: Bueche F. , Harding S. W. 
Published: February 2011

Abstract
It has been shown that the shear-rate dependence of the viscosity of concentrated polymer solutions can be explained in terms of known parameters of the solution. If the concentration, temperature, zero shear viscosity, and molecular weight of the polymer are known, the decrease in viscosity with increasing shear rate can be predicted. Conversely, if one measures the shear-rate dependence of the viscosity, the molecular weight may be computed. We believe this provides a convenient method for the absolute determination of molecular weights of linear, coiling, high polymers.
Stress-Strain Equation for Rubber in Tension
Authors: Claxton W. E. 
Published: February 2011

Abstract
A stress-strain equation is derived for a homogeneous, isotropic material with the assumptions that for any given homogeneous simple tensile strain, the components of the stress tensor are to the first approximation linear, homogeneous functions of the components of the strain tensor and that no volume change occurs during the deformation. Utilizing the dependence of Poisson's ratio upon the extension referred to the initial coordinates, one elastic coefficient, C12, is found to be sufficient to roughly characterize the first stretch stress-strain curve. Although experimentally this elastic coefficient is found to be essentially constant for extensions greater than 250% its value increases rapidly as zero extension is approached. This behavior agrees qualitatively with data by Blanchard and Parkinson as to the distribution of secondary bond strengths, wherein they found a large number of relatively low-energy bonds which would be effective only at small extensions in contributing to modulus reinforcement. Various aspects of stress strain and cure behavior are examined with the derived equation as a basis.
Mechanical Behavior of a Polymer at Temperatures through the Glass Transition Temperature
Authors: Stevens J. R. , Ivey D. G. 
Published: February 2011

Abstract
Stress-temperature (constant strain) and length-temperature (constant stress) measurements have been made on Paracril-35 (a butadiene-acrylonitrile copolymer) in the temperature range −80° C to 25° C, which includes the glasslike, transition, and rubberlike states for this material (Tg∼−25°C). Time effects are observed in the transition region, but for temperature gradients used (down to about 1° C in 4 hours) the behavior at low temperatures is unique, indicating the existence of a real transition. This behavior is independent of the strain imposed at room temperature. The shift in transition temperature (in the length-temperature work) with extension is found to give quantitative support to the theory that the transition occurs at a certain minimum volume. In the rubberlike region, behavior is represented by the usual equation of state.
The influence of Intermolecular Action on the Dynamic Fatigue of Rubbers
Authors: Gul V. E. , Fedyukin D. L. , Dogadkin B. A. 
Published: February 2011

Abstract
The determination of the physical effect of softeners by an investigation of their influence on the swelling of vulcanizates is a convenient method for investigating the optimum composition of a compound which will produce given properties in the cured stock. This makes possible the improvement of such important properties of vulcanizates as fatigue resistance, mechanical loss, freeze resistance and others by using softeners with the appropriate functional groups.
Distribution of Side Force and Side Slip in the Contact Area of the Pneumatic Tire
Authors: Cooper D. H. 
Published: February 2011

Abstract
It is well known that, when a pneumatic tire is rolled over dry ground at a slip angle, a sideways force is developed. With the cornering force rig described here we are able to measure the front to rear distribution of the cornering force along the contact spot, the length of the contact area, the trail and the self-aligning torque. At the same time it is possible to derive the shape of the distorted tread and the front to rear distribution of side slip in the contact spot. By making certain assumptions concerning the distribution of the vertical force along the contact spot a relationship has been established between the forces of friction, rate of side slip and speed of rolling.
Effect of High Pressure on Self Adhesion (Autohesion) of High Polymers
Authors: Igonin L. A. , Ovchinnikov Yu V. , Arzhakov S. A. 
Published: February 2011

Abstract
The phenomenon of self adhesion of high polymers is one of the very important but little studied properties of these materials. Self adhesion of rubberlike polymers has been studied, but there is little work reported on the self adhesion of thermoplastics. There is, however, no doubt about the importance of the role of this phenomenon in the process of producing products from powdered and granular thermoplastics. The influence of temperature and pressure on the self adhesion of some thermoplastic powders was studied in the present work. The conditions for the formation of a transparent sample were found by pressing the powdered material in a heated cylindrical press. The samples pressed were 10 mm in diameter and 4–5 mm thick. The temperature and pressure were varied over a wide range. The samples were pressed in the following manner: The polymer sample was placed in the cold press and a given pressure was applied; the temperature was then raised to a given value and the sample was held at this temperature for 15 minutes; after cooling the press to 50–60° the pressure was released, the sample was removed from the press and the density to visible light was evaluated visually. When a transparent sample is obtained by pressing the thermoplastic polymer, partial or complete coalescence of the grains of the material takes place with a disappearance of grain boundaries. Under these conditions the strength of the sample may not reach the cohesive strength of the material as has sometimes been assumed.
The Coagulation Mechanism of Butadiene—Styrene Latex
Authors: Glikman S. A. , Korchagina E. P. 
Published: February 2011

Abstract
1. It is shown that the absolute values of the coagulation thresholds of SKS-30A latexes diluted down to 0.01% correspond to the usual values for lyophobic sols. The values for NaCl are 200 times those for CaCl2, and increase with the latex concentration. The complete coagulation concentration for NaCl is 30 times that for CaCl2, and does not depend on the dilution of the latex. 2. It was shown by a nephelometric method that the volume of the primary particles formed in coagulation of the latex by sodium chloride is about 10 times the volume of the uncoagulated latex globules, irrespective of the latex concentration. 3. Consideration of the experimental data, in conjunction with facts reported in the literature, leads to the concept of two stages in the coagulation of latex by electrolytes: the first is the consequence of a decrease of the zeta potential, leading to the formation of primary particles, and the second leads to coalescence of these particles. The secondary aggregation processes can be prevented or modified by introduction of certain additives (nonelectrolytes) into the latex. 4. In additon to an explanation of the mechanism of latex coagulation by electrolytes, and a demonstration that this process can be controlled, indications are given of means of an approach to development of conditions for the production of a good blanket by coagulation of latex by sodium chloride, with a much decreased consumption of the latter.
The Structure of Gels. X. Globulization of Rubber under the Action of Nonsolvents
Authors: Zubov P. I. , Zhurkina Z. N. , Kargin V. A. 
Published: February 2011

Abstract
1. Addition of nonsolvents to rubber solutions causes globulization of the macromolecules, similar to that occurring on addition of active substances (sulfur monochloride, halogens, etc.) to rubber solutions. 2. The difference between these processes lies in the fact that the coiling of the rubber molecues under the action of methyl alcohol is very rapid. 3. The globular structures in rubbers, produced by addition of nonsolvents to the solutions, in contrast to the stable globules formed in halogenation and vulcanization of rubber solution, are easily broken down and the molecules assume the linear form characteristic of the original rubber.
Vulcanizates from Natural Rubber and Bisazo Compounds. Aging Properties
Authors: Esser Heinz 
Published: February 2011

Abstract
Nonblack as well as black loaded natural rubber compounds were vulcanized by addition of hexamethylene-1,6-bis(phenyl-azomonocarbonamide) (BAA). The accelerating and vulcanizing action of BAA is discussed on the basis of modulus curves. The experiments show that BAA alone is not active as a vulcanizing agent. To achieve good vulcanization, sulfur is also needed; the optimum sulfur level is much lower than in normal compounds. Furthermore, it is shown that BAA compounds need addition of an accelerator. Aging stability of BAA vulcanizates was tested by modern rapid tests (relaxation, creep, and oxygen absorption) as well as by classical methods (hot air and oxygen bomb aging). Vulcanization in which BAA was substituted for part of the sulfur showed excellent aging, comparable only with thiuram vulcanizates in the rapid tests and in hot air aging; aging in the oxygen bomb gave only fair results.
Effect of Vulcanization on the Dynamic Properties of Rubber
Authors: Kuvshinskiĭ E. V. , Sidorovich E. A. 
Published: February 2011

Abstract
It is a known fact that the mechanical properties of rubber depend essentially upon the density (i.e., the crosslink density) of the vulcanization network. The dependence of the “equilibrium” (statistical) modulus of elasticity upon the concentration of crosslinks as well as the dependence of the tensile strength —has been studied in a series of investigations. In contrast to this, analogous investigations of the dynamic mechanical characteristics are practically nonexistent. We have undertaken our present work with the hope of filling this gap. Series of gum compounds were prepared from natural (smoked sheet) and synthetic polyisoprene (SKI), sodium butadiene (SKB), butadiene-styrene (SKS-30A), and butadiene-nitrile (SKN-26) rubbers which varied in their degree of vulcanization. The percentage of sulfur and accelerator were varied as were the temperature and the time of vulcanization. The mechanical-dynamic characteristics of the rubber at a predetermined impact pressure—the rebound elasticity and the dynamic elastic modulus were studied with the pendulum elastometer KS over a temperature range of 20–100° C. The duration of the stress was .03/.05 second. We estimated the concentration of crosslinks in the rubber samples from the magnitude of the equilibrium modulus. In order to determine this characteristic, we compressed specimens which were 20 mm in height and 10 mm in diameter 15% and studied the relaxation of stress. The specimens were also tested on the pendulum elastometer. Heppler's consistometer operating on the lever weight principle, was adapted for our measurements. The experiments were conducted at 60° C, the thermostatic control being effected with the help of Heppler's ultrathermostat.
Intermolecular Interaction in Rubber Solutions
Authors: Gul V. E. , Berestnev V. A. 
Published: February 2011

Abstract
A study has been made of the viscosities of butadiene acrylonitrile rubber solutions and of the equilibrium swelling of vulcanizates of these rubbers with the same degree of crosslinking, in various solvents. It was found that the viscosity and light scattering characteristics of the solutions, and swelling of the vulcanizates of butadiene acrylonitrile rubbers are not steady functions of the degree of intermolecular interaction, represented by the difference of the square roots of the cohesive energy densities of the polymer and the solvent but pass through a maximum with variations in the polarity of the rubber.
Wandering of Crosslinks in Rubber at High Temperature
Authors: Voorn M. J. , Hermans J. J. 
Published: February 2011

Abstract
There are strong reasons to believe that on heating a crosslinked rubber crosslinks are broken and new ones formed. This has been established by the well-known work on stress relaxation of Tobolsky and his school, and others. In the following we will discuss some experiments which give further support to these views, both of a qualitative and quantitative nature. In the first place, we carried out a few preliminary experiments on stress relaxation at elevated temperatures. This stress relaxation may be due to either or both of two effects : (a) a displacement of the crosslinks, (b) a change in the number of crosslinks per unit of volume (crosslinking density p). A measure of ρ can be obtained from the equilibrium degree of swelling at room temperature, and this gives us a means of comparing changes of ρ in a stretched sample with those occurring in the unstretched state. To this end commercial rubber strips were heated in the stretched state in the absence of oxygen at three different temperatures (80, 106, 122° C) for times varying from 2 to 72 hours. The degree of stretch, i.e., the length of the stretched rubber divided by the original length was α=1 (unstretched) in one series, and α=3 in a second series. The initial stress τ0 (for α=3) and the final stress τ at the end of the heating period were read from the stress-strain diagrams, taking into account that for the heat-treated strips there was a permanent set. In other words, τ is the stress needed to give the heat-treated sample at room temperature a length 3 times the length of the original untreated sample; the ratio τ/τ0 is therefore essentially the ratio between the moduli of elasticity. The cross-linking densities ρ0 and ρ before and after heating were derived from swelling experiments (for details see the sections on swelling).