bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theory of Random Filler Dispersions in Rubber
Authors: Gehman S. D. 
Published: February 2011

Abstract
Ideal mixing results in random filler distributions in rubber, in which case the number of particles in a field follows the Poisson distribution deduced from probability theory. There should be no advantage in continuing the mixing after a random distribution has been achieved. The closeness of the approach to a Poisson distribution is to be ascertained by counting the number of particles in many small fields. Random configurations of particles may sometimes be deceptive in suggesting the existence of attractive forces between the particles. The frequency distribution for the thickness of the rubber matrix between the particles in a random distribution is derived by use of a suitable model and probability considerations. The frequency of occurrence decreases exponentially with increase in thickness and is a function of the particle diameter and the volume loading. In theory, the same thickness distribution can be obtained for fillers differing in average particle diameter by suitable variations in the loadings. As a practical matter, the thickness distributions with the finer rubber fillers cannot be duplicated with coarse fillers because of the high loadings required. The model is used to estimate the modulus enhancement to be expected from an increased crosslinking density at the surface of a reinforcing particle which decreases exponentially with the distance from the surface. The results indicate the possibilities of this mechanism for explaining the enhanced modulus exhibited by reinforcing as contrasted to inactive fillers.
Reinforcement of Natural Latex Rubber by Carbon Black and Ionizing Radiation
Authors: Lamm A. , Lamm G. 
Published: February 2011

Abstract
The study of the reinforcement of rubber by carbon black has made it possible to establish the radical nature of the interaction, thus explaining why, in the latex phase and in the absence of sources of radicals, the reinforcing effect of carbon black does not exist and why it has been possible up to the present to obtain it only by mastication of the solid rubber in the presence of black. Irradiation, an excellent source of radicals, should in latex systems lead to a reinforcement of rubber by black. The experiments carried out appear to prove this. Irradiation of the latex and the black in aqueous dispersion, followed by a mixture of the two constituents which is then poured out on a plate, dried and subjected to moderate thermal treatment, makes it possible to obtain mechanical properties which are definitely superior to those of films prepared without irradiation and of films vulcanized with sulfur.
A Molecular Theory of Filler Reinforcement Based on the Concept of Internal Deformation
Authors: Sato Yoshiyasu , Furukawa Junji 
Published: February 2011

Abstract
A molecular theory is presented which gives an analytical method to describe filler-reinforced heterogeneous elastomers and the cavitation therein caused by elongation. By using a suitable model and a new concept a proper method of analysis for a heterogeneous system is obtained. By means of this method the overall internal mechanism of filler reinforcement can be understood; especially it is made clear that reinforcement consists of three effects: a volume effect, a surface effect and a cavitation effect. Also, formulas for several main quantities are derived: tension, swelling tension, Young's modulus, local stress distribution, condition for swelling equilibrium, etc.
The Structurization in Hydrocarbon Suspensions of Carbon Black in Relation to the Behavior of Active Rubber Fillers
Authors: Yampolskiĭ B. Ya , Shu-Tsiu U. , Rebinder P. A. 
Published: February 2011

Abstract
In spite of the numerous investigations of the reinforcing properties of active rubber fillers, up until now the role of interacting particles of fillers, both between themselves and with the dispersion medium, for example macromolecules of polymers, has not been clear. No physico-chemical mechanism for the function of active rubber fillers have been clarified. We have studied the processes of structurization in model systems, using carbon black as an important example of rubber filler. The investigations were conducted with concentrated suspensions in nonpolar hydrocarbon media. The influence of filler content, polymer concentration, surface tension, wetting agents and temperature were studied. We employed the method of measurement of electrical conductivity, recording volt-ampere curves, using a wide range of potential gradients. At the same time, studies of the mechanical structure properties (thixotropy) of the suspensions were made. Volt-ampere curves were obtained from data recorded during the introduction of constant current voltages in intervals ranging from 0.01 V to 100 V. The corresponding fluctuation of potential gradient was of the 4th order, from 0.25 to 250 V/cm. The measurements were carried out over a period of three hours immediately after preparation of the experimental suspension. Thus a suspension of Type A lamp black in non-polar mineral oil was prepared by a standard method, assuring good reproducibility in the experiments. In the period of three hours specific conductivity of greatest value, λm was obtained, with practically no change with time, testifying to the completion of the process of coagulation, or gel structure
Relation of Physical Behavior to Molecular Packing in Crosslinked Rubber
Authors: Mason P. 
Published: February 2011

Abstract
The physical consequences of crosslinking a polymer are, first, the establishment of the molecular network on which the equilibrium rubberlike elasticity depends; Flory has shown how the creation of this network leads to an increase in the internal pressure of the system, so that crosslinking will be expected to produce a reduction in volume on this account alone. Secondly, there is another, more localized, change in molecular packing resulting in a reduction in volume, an increase in the glass-transition temperature, and a shift of the mechanical and dielectric dispersion regions towards higher temperatures. Structural interpretation of these effects has hitherto been impeded by three difficulties: (i) the determination of crosslink density; (ii) the presence of the “foreign” atoms constituting the crosslink; and (iii) modifications to the polymer chains occurring during crosslinking. A system is therefore being studied in which these difficulties are largely avoided. Purified natural rubber is heated with dicumyl peroxide for 1 hour at 140° C; the resulting crosslinks are direct covalent bonds between carbon atoms in neighboring chains. No “foreign” atoms are introduced, and there is substantially no modification of the rubber molecules. After extraction and drying, the equilibrium degree of swelling in n-decane is measured and used to obtain the crosslink density by reference to the original chemical determinations of Moore and Watson. Measurements are then made of the specific volume at 20° C, the thermal expansion behavior and the dynamic mechanical behavior, both over a temperature range including the glass-rubber transition.
Dynamic Testing Apparatus for Rubbers and Plastics
Authors: Trivisonno N. M. , Stearns C. A. , Kime J. M. 
Published: February 2011

Abstract
A dynamic testing apparatus for rubbery and plastic materials has been built. Operation is based on the principle of the electromechanical transducer. Dynamic properties are calculated from direct measurements of the force generating current, the velocity produced voltage, and the phase angle between them. Frequency range is 50 to 500 cps, temperature range −25° C to 100° C, and strain range 0.01 to 0.0001. Results are presented for a standard polyisobutylene sample, natural rubber, synthetic cis-polyisoprene, and perdeuterio cis-polyisoprene. No significant differences were found among the latter three.
The Relation between Structure and Physical Properties in Polyurethans
Authors: Tanaka Takehide , Yokoyama Tetsuo 
Published: February 2011

Abstract
The field of polyurethans is rapidly growing in commercial importance, especially in form and elastomer applications. This group of polymers includes a very broad region of chemical structures and chain length. In many cases polyurethans are synthesized from polyester glycols or polyether glycols and diisocyanates so that the urethan groups are even fewer in number than other functional groups. This process of synthesis enables us to deal with a very wide range of polymer properties, adding interest to the studies of relation between structure and properties. Though a considerable number of publications dealing primarily with the properties of urethan polymers have been published, few of them contribute to better understanding of the relation between these properties and the corresponding polymer structure. Within the last few years information of value has become available, and Saunders has established some semi-quantitative relations by the use of such data. He also discusses in his reports general considerations concerning structure-property relationships. Although his considerations and conclusions show a marked progress, they are not theoretically satisfactory yet, especially from a quantitative viewpoint. The authors have investigated structure-property relationships in polyurethans for a few years and written some papers concerning synthesis, reaction kinetics, some physical properties, network structure, and dynamic behavior of polyurethans.
Volume Changes and Dewetting in Glass Bead-Polyvinyl Chloride Elastomeric Composites under Large Deformations
Authors: Smith Thor L. 
Published: February 2011

Abstract
Elastomeric materials loaded with inert filler have Theological properties which, on the one hand, are qualitatively like those of unfilled polymeric materials, but which, on the other hand, are unique to filled systems. Their stress-strain curves usually have several distinct regions which are similar to those for certain unfilled polymeric materials. The curves have an initial region in which the stress increases with strain, and here the modulus depends primarily on the amount of filler and the properties of the binder. In the second region, the stress may be roughly independent of the strain or may increase at a rate markedly less than that in the initial region. The transition between these two regions may be either gradual and hardly perceptible or sharp, with a well-defined yield point. Thus, in these two regions, the stress-strain curves may be like those for typical unfilled rubbers or for plastics, or they may resemble the curves for rubbers at low temperatures, which cold draw or neck. In the third region the stress increases more rapidly with strain than in the second region and continues to increase until the specimen breaks; again, this is similar to what is observed for certain plastics and rubbers. Thus, both filled and unfilled systems can have sigmoidal stress-strain curves which may or may not have distinct yield points. However, filled systems, and especially those in which the binder wets, but does not react chemically with the filler, exhibit the sigmoidal-type stress-strain curve for different reasons than do rubbers and plastics. In filled systems, the binder adheres to the filler initially, which reinforces or strengthens the system. However, in the transition and second regions of the stress-strain curve, adhesive bonds between the filler and binder break, a process called dewetting, and vacuoles form around the filler particles. After the adhesive bonds are essentially all broken, a further increase in strain only stretches the binder further and enlarges the vacuoles.
The Pico Laboratory Abrasion Test
Authors: Newton Edwin B. , Grinter Hershel W. , Sears D. Scott 
Published: February 2011

Abstract
The Pico abrasion tester can be adjusted to simulate wide conditions of severity. It can also be adjusted to approximate the severity of test encountered in ordinary 60 mph road tests to give laboratory data which agree fairly well with road results. It can evaluate tread stocks made with different polymers quite as well as evaluate different carbon blacks in the same polymer.
The Shape of Specimen and the Measurement of Permanent Set
Authors: Yabuta Shiro 
Published: February 2011

Abstract
Stress distributions in an ASTM or JSI-specimen and a rectangular strip specimen were investigated. It is concluded that the dumbbell type specimen is not suitable for the determination of permanent set, because of the considerable variations of stress concentration due to the influence of the curved parts on the parallel part. The strip specimen, deforming uniformly, is preferable to the dumbbell specimen.
Effects of Carbon Black Structure on Tire Tread Wear
Authors: Bolt T. D. , Dannenberg E. M. 
Published: February 2011

Abstract
Oil furnace process carbon blacks have been produced which differ widely in the extent of their primary chainlike aggregation. The effect of the carbon black structure on rubber properties and road wear was evaluated in oil-extended SBR passenger tire tread compounds. The decrease in primary particle aggregation increases the tendency to form strong, dense, secondary agglomerates which require mixing techniques designed to insure that they are well dispersed. The behavior in rubber of a series of oil furnace blacks differing primarily in their structure is most apparent in processing, shrinkage, modulus and hardness. There are small effects on rebound and flex cracking resistance but no significant effects on tensile strength and heat buildup. Carbon black structure can be reduced to some extent without encountering significant loss in road wear resistance under normal wearing conditions. Some decrease in road wear performance occurred under very severe road test conditions. The use of higher black loadings of the normal structure blacks gave good wear resistance under both normal and severe service conditions.
Rupture of Rubber. VI. Further Experiments of the Tear Criterion
Authors: Thomas A. G. 
Published: February 2011

Abstract
In previous papers (I to V of this series), a tear criterion for rubbers has been proposed based on an energy balance approach. This equates the energy required to form new surfaces (the tearing energy) with the loss of elastic strain energy in the test piece. The tearing energy T is assumed to be characteristic of the material and so independent of the overall shape of the test piece. It is thus the fundamental property controlling tear behavior. The correctness of this approach was investigated by making tear measurements on test pieces of different shapes but of the same material and examining the constancy of the T values obtained. The results were consistent with the theory but not wholly conclusive, due primarily to the particular tearing behavior of the materials used (natural rubber gum vulcanizates). Another limitation was that accurate T values could be obtained only if they could be calculated directly from the measured tearing forces or elongations, and the required relationships were known for only two types of test piece. Clearly, the more test pieces available for comparison and the more they differ from each other in shape, the more stringent the test of the basic theory. In the present paper a third test piece is described, the necessary theory given, and experimental results presented on the three test pieces. By comparing the results from these test pieces, which are of widely different shapes, a critical test of the theory is possible. The choice of the experimental material is influenced by several factors. Previous measurements have been made on natural rubber gum compounds, which have the advantage of possessing excellent elastic properties but whose rupture characteristics are such that tearing occurs at a critical load. In contrast, a gum GR-S tears more or less steadily at a rate depending on the load, a characteristic which is experimentally advantageous for the particular test pieces described here. It was therefore used in this investigation.
Rupture of Rubber. VII. Effect of Rate of Extension in Tensile Tests
Authors: Greensmith H. W. 
Published: February 2011

Abstract
There are few published measurements on the effect of rate of extension in tensile rupture tests on rubber vulcanizates. The most extensive data on a single vulcanizate are those of Dogadkin and Sandomirskii˘ and of Smith. These measurements were made on GR-S gum vulcanizates and covered a similar range of rates of extension, from about 0.02 to 20%/sec. Ring specimens were used in both cases, and tensile strength and breaking extension were measured over a wide temperature range. Villars has made tensile strength and breaking extension measurements on double dumbbell specimens of several gum and filled vulcanizates extended at various rates in the range 10,000 to 100,000%/sec. Kainradl and Handler have reported tensile strength measurements for several filled vulcanizates, obtained with dumbbell specimens extended at four different rates of extension covering a range from about 1 to 100,000%/sec. All these results indicate that tensile strength and breaking extension can vary appreciably with the rate of extension of the specimen. Complete load-extension curves are not given in any of these papers. In the present paper an autographic method is described for obtaining the load-extension curves of ring specimens extended at various rates from about 0.1 to 2000%/sec. Results showing the effect of the rate of extension on the tensile strength and breaking extension and on the load-extension curve are given for GR-S vulcanizates. The data were obtained primarily for the comparisons of tear and tensile rupture measurements given in a subsequent paper (Part VIII).
Newer Synthetic Rubbers Derived from Olefins and Diolefins
Authors: D'Ianni J. D. 
Published: February 2011

Abstract
Synthetic rubbers are of significant interest to the petroleum industry, since nearly all of the raw materials required in their production are petrochemical in nature. Many of these petrochemicals are produced in large quantities for other chemical end uses as well. Among the most important of these large-tonnage intermediates are butadiene, styrene, acrylonitrile, chloroprene and isobutylene. The newer developments in synthetic rubber, to which this paper will largely be devoted, have focused greater attention on other monomers, such as isoprene, ethylene and propylene. The following figures will give some idea of the present and future consumption of these raw materials, largely based on petroleum, for chemical manufacture:
The Nature of Static Friction in Elastomers
Authors: Bartenev G. M. , Lavrent'ev V. V. 
Published: February 2011

Abstract
1. A method free from the shortcomings of earlier work is proposed for the measurement of the friction of elastomeric materials in the initial moment of shear. 2. From results of measurement of friction of rubber on steel it follows that static friction, determined as the coefficient of friction in the initial moment of slip, is a conventional parameter, since it depends upon the accuracy of measurement of the movement and upon the rate of application of the tangential force. 3. The conventional coefficient of static friction of elastomeric materials is particularly evident at low rates of application of the tangential force, which fact is connected with the nature of dry friction of rubberlike polymers.
Molecular Basis for The Mullins Effect
Authors: Bueche F. 
Published: February 2011

Abstract
The physical phenomena now widely known as the “Mullins effect” was apparently first studied in detail by Holt in about 1930. He showed that if a vulcanized rubber which contains carbon black is stretched to a relative elongation αm=L/L0 and released, it will not follow the same stress-strain curve when it is stretched once again to this same elongation. Instead, the rubber appears much softer on the second stretch for elongations below αm. Holt examined this behavior in some detail and showed that additional pre-stretches to αm softened the rubber further, but to a lesser degree than was observed on the first prestretch. In addition, Holt showed that the rubber regains a portion of its stiffness if allowed to rest in the relaxed state. Although this recovery was very slow at room temperature, up to about 50% recovery was noted after about an hour at 100° C. Similar softening effects were noted in gum stocks at exceedingly high elongations, but the effects were much less marked than in the filled stocks. This same effect was examined in more detail by Mullins after 1940. His results confirmed and greatly extended the earlier results of Holt. In addition, Mullins speculated about the mechanisms involved but came to no definite conclusion in that regard. Later, however, he and Tobin presented a phenomenological theory for the effect wherein they considered the rubber to be composed of hard and soft regions. They showed that their data could be described by assuming that some fraction of the hard regions became soft after a prestretch. No definite molecular basis for this process was proposed by Mullins and Tobin, although they speculated that either the breaking up of filler particle aggregates or the breaking loose of rubber to filler bonds might be involved. Later work by Blanchard and Parkinson confirmed and extended the data of Holt and Mullins. Further, these authors concluded that the softening was due to the breaking of rubber to filler bonds. They incorporated this idea into a semiempirical theory which agreed with their experiments. In addition, they obtained what they believed to be a distribution for the strength of the rubber-filler bonds. It will be seen in that which is to follow that their distribution probably does not represent what they thought it did, even though their basic ideas were correct.
Non-Linearities in Dynamic Tests II. Impact and Rolling Wheel Tests
Authors: Gough V. E. 
Published: February 2011

Abstract
Viscoelastic properties of rubberlike materials are currently studied by a number of methods: vibration methods involving a single degree of freedom system, measurement of the stress-strain curves under cyclic application of deflection, impact tests and tests using rolling wheels. The effect of non-linearities on the motion of a single degree of freedom system is discussed in detail in Reference 1 and it is concluded that the analysis employed must not contain an arbitrarily assumed equation of motion nor an arbitrary stress-strain relationship if the objective of the tests is to determine the true character of the viscoelastic properties and to relate these to the molecular properties of the material. The character of the viscoelastic properties must be derived from experiment by methods free from inbuilt mathematical assumptions and it is shown that phase plane analysis can be adapted for that purpose. It is also noted in Reference 1 that measurement of the stress-strain properties during cyclic application of deflection is free from inbuilt mathematical assumptions. The question which is examined in this related paper is whether the study of impact tests and rolling wheels using energy methods is subject to similar and/or other necessary conditions.