bluuebunny/crossref_metadata_2025 huggingface dataset:
An Inorganic Rubber
Authors: Renaud Paul
Published: February 2011

The hypotheses generally accepted for the structure of gels explain these phenomena in detail. The trimer, polymerized by heating, gives rise to chains of different sizes, which are able to unite and form a network. The latter contains in its meshes the trimer which has not reacted, and also polymers of low molecular weight. According to whether the latter form a liquid or solid mixture, the gum is optically liquid or solid. At low temperature, the network itself assumes a rigidity which it communicates to the entire mass. The thermo-mechanical properties show that this is true of all the gums. The presence of the network has little influence on the fusion of the intercellular product, whereas its influence on vaporization is great; in fact, the volume is as little affected by fusion as it is greatly changed by vaporization. It must therefore be the case that rupture of the meshes by pressure is more rapid than their formation by polymerization. The influence of benzine and of water, one of which dissolves the intercellular products and the other does not, shows the influence of osmotic pressure, to which Duclaux (see Bull. soc. chim., 33, 36 (1923)) has called attention.
Note on the Absorption of Oxygen by Sheets of Rubber
Authors: Linhart George A.
Published: February 2011

Very interesting and commercially very important experiments have recently been made in the Bell Telephone Laboratories by G. T. Kohman on the absorption of oxygen by sheets of rubber. No attempt, however, was made to interpret the results mathematically. It is true, of course, that any empirical equation to express the course of the process would be merely a sort of garnish. It would be interesting, however, to show that these processes are not unique. Some years ago the writer published an equation which described the progress of many processes in the fields of chemistry, botany, biology, bacteriology, etc. It is based upon the results of the tossing of a coin, and represents in fact the law of uni-directional probability. The derivation of the equation is rather lengthy. In this note the equation will be applied to the process of the absorption of oxygen by sheets of rubber. In the original article cited above the numerical data are not given, but they are so well shown on the graphs that the results may be read off to within one per cent. The amounts of oxygen, therefore, given in the table of this note are expressed in millimeters read off on the original graph, while the time is expressed in hours.
Coherent Expanded Aerogels
Authors: Kistler S. S.
Published: February 2011

There are few topics in colloid chemistry that have experienced such extensive investigation as that of the structure of gels. Numerous hypotheses have been presented and supported by experimental data of one character or another. Certain aspects of gels have seemed to classify them as solid solutions, others as emulsions, while yet others give strong support to a two-phase, solid-liquid structure. Although the latter theory in similar form to that postulated by Nägeli in 1858 has been accepted by most of the foremost colloid chemists, the evidence has not been sufficiently unequivocal to convince all. The evidence presented in the results of diffusion experiments through gels, the fact that the electrical conductivity, refractive index, and vapor pressure before and after setting are identical, at least in certain cases, and the known facts of syneresis would seem to leave little room for doubt of the two-phase nature of gels in general. A theory in order to be perfectly acceptable must, however, enable verifiable predictions to be made from it.
Further Studies of Rubber Solutions
Authors: Shacklock Cecil W.
Published: February 2011

1. The refractive index of rubber is not appreciably affected by mastication for five hours in the cold. 2. The refractive index of solutions of rubber indicates that solvation of the rubber hydrocarbon is independent of the time of milling of the rubber. 3. The oxygen, which is continuously absorbed by rubber during mastication in air, reacts with the rubber, evolving oxidation products, and also forms addition products. It is suggested that this addition of oxygen reduces the micellar binding forces and so permits easy mechanical disaggregation. 4. The acetone extraction of rubber increases progressively with the period of mastication of the rubber. 5. The surface tension of solutions of rubber milled for varying periods increases with the time of milling, and subsequently remains constant. This is possibly due to the oxidation products from the end-groups of the hydrocarbon chains. Such end-groups are more open to attack by oxygen than the rest of the chain; further, there is a limit to the number of end-groups available for reaction (two per chain) while the number of unsaturated linkages between the end groups is undoubtedly many, and each of these is a possible point of oxygen action.
The Effect of Simple Carbohydrates on the Vulcanization of Rubber
Authors: Bishop R. O. , Rhodes E.
Published: February 2011

In continuation of investigations on the vulcanization effects of Hevea lipin (Quarterly Journal, Vol. 2, No. 3) the question arose as to the possible influence of the sugar with which lipin is known to be associated. The fact that, in spite of the presence of sugars, the behavior of raw rubber plus lipin on the mixing rolls is apparently similar to that of raw rubber plus lecithin, suggests that the sugars might be without influence. While it is recognized that, for the proper understanding of their influence, it is essential to isolate and characterize the free sugars present in latex, it was considered that the vulcanization effects which we had observed were sufficiently significant in their possible bearing on plantation rubber variation to call for further investigation, and although our subsequent observations cover only a limited field somewhat divergent from the main line of work, it appears that the present results are worth recording.
Studies on the Aging of Vulcanized Rubber. XI. Consideration of the Influence of Free Sulfur on Aging of Vulcanized Rubber
Authors: Yamazaki T. , Okumura K.
Published: February 2011

Although it has been generally known that free sulfur in a vulcanized rubber is likely to change into sulfuric acid during aging, the authors pointed out in their Ninth Report that a part of the combined sulfur also decomposes during aging, with the formation of sulfuric acid. Therefore the authors in this report proceeded to find the relation between the proportions of free sulfur in vulcanized rubber at the state of optimum cure and its aging. The samples used for these experiments were as follows:
The Elasticity Constants of Rubber under High Tensions
Authors: Weise Rudolf
Published: February 2011

The problem of determining the elasticity constants of rubber involves various difficulties. Since the material under investigation frequently has very different chemical properties, even when under the same name, no wholly consistent results are to be expected of physical tests. Moreover, it has been found by experience that tests of samples cut from the same sheet differ greatly. Ordinarily these variations must be accepted as inevitable. However, as the present work will show by way of example, these variations can be kept within certain limits through a proper utilization of a number of experiments. From a technical point of view, the study of elasticity is concerned chiefly with the properties of isotropic substances. Since, upon stretching, rubber becomes anisotropic, the question naturally arises whether mathematical formulas which are valid for isotropic substances have in general any meaning when applied to rubber. Furthermore, it should be mentioned at the beginning that Scherrer has proved by x-ray photographs that in the unstretched state rubber is an amorphous substance. Only at an elongation of about 100 per cent do interferences appear, so that, at least for our purpose, rubber can be regarded as “quasi-isotropic” up to this degree of elongation. This may also be justifiable to a certain extent even at higher elongations since, in describing the elastic properties, the volume is the only function used besides direct measurements, and the volume changes at the most only 2 per cent up to the highest elongations. A large amount of work has been done on the modulus of elasticity and the Poisson constant of rubber. An examination of the literature at present showed, however, that measurements cover at the most only a small part of the possible range of elongation. Only Bjerken and Villari have undertaken experiments at higher elongations as well. The latter investigated the modulus of elasticity up to 6 times, the former the Poisson constant up to 5 times the initial length. The object of the present work therefore has been to determine both constants of elasticity, viz., the modulus of elasticity and the Poisson constant; over the entire range of elongation, with particular attention to determinations of the modulus of elasticity just previous to rupture. To eliminate the temporary after-effect a kinematographic method of measurement was used to advantage. By the same method it was possible to obtain data upon the behavior of rubber up to the point of rupture. To complete the picture of elastic properties, the permanent set as a function of the time and tension was determined.
Laboratory Rubber Testing. Its Relation to Service
Authors: Dinsmore R. P.
Published: February 2011

The rubber technologist of today is situated in one of the most competitive and rapidly changing industries. He is faced with the necessity of producing an important structural material of varied forms and compositions which must constantly be modified to meet new requirements of economy and service. He must be prepared to furnish, upon demand, rubber in new forms and colors, which will serve successfully in increasingly exacting conditions of temperature, flexing, abrasion, and more often than not in conjunction with a totally dissimilar material. To anticipate these demands he must engage in a ceaseless search for new and more effective materials, both in his own research laboratory and amid the countless new natural and synthetic materials which appear on the market. The time has passed when long periods of preparation can be utilized for the development of new compounds and products. The pressure of modern industrial development constantly brings about new conditions which must be met when they arise. The success with which the technologist fulfils these obligations depends in large measure upon his ability to predict the behavior of his materials under the conditions of service. When, as is often the case, his knowledge of both materials and service conditions is limited, results frequently fall far short of expectations.
Factory Mixed Stocks Method for Maintaining Uniformity
Authors: McCarty J. E. , Cousins Edward
Published: February 2011

Close control of milled rubber stocks is important to all rubber manufacturers. The present system developed by the authors is based on the determination of loads for given elongations, using a modified dumbbell strip. An outline of the testing routine follows. Samples from every milled or Banbury mixed batch come to the control laboratory, each sample being accompanied by an identifying card which contains provision for recording all data of interest on that particular batch. As the samples arrive, they are weighed on a laboratory scale to give a definite volume. The molds used for curing contain 32 cavities, each with overflow channels; the cavities are numbered to permit identification of the samples. Each cavity is 1.25 inches (3.18 cm.) by 2.5 inches (6.35 cm.) by 0.125 inch (0.32 cm.). The samples are placed in the hot mold, each in its appropriate cavity, and given a short cure at 320° F. The pieces are then removed and cut out with a die to give a dumbbell strip of the dimensions given in Fig. 1. The die is open at the ends but is long enough to overlap the edges of the small slabs, thereby facilitating the separation of the test strips from the remainder of the slab.
The Rubber Pendulum, the Joule Effect, and the Dynamic Stress-Strain Curve
Authors: Wiegand W. B. , Snyder J. W.
Published: February 2011

General Description.—The rubber pendulum is one of two devices (Wiegand, Trans. Inst. Rubber Ind., 1, 141 (1925)) which, by employing the Joule effect, constitute rubber heat engines in that they continuously convert heat into mechanical work. In Fig. 1 is shown the original pendulum. It consists of an ordinary pendulum of slow period fitted with a rubber band, one end of which is attached to the bob; the other to the upright support. This rubber band is stretched to four or five times its original length. Behind the upright is a metal shield so arranged that when the bob has reached the extremity of its swing the rubber band is clear of the shield, during the rest of the oscillation being in its shadow. Behind the pendulum and shield is an electric heating element with a copper reflector. The pendulum is started by displacement from the center towards one or other extremity. As this is done the rubber band is increased in length. At the extremity of the oscillation the stretch band is exposed to the radiant heat from the element, the Joule effect is brought into play and the band tends to shrink, thus pulling back the bob. Directly the band moves back within the shadow of the shield it cools, relaxes, and so allows the bob to swing out to the other side. Thereupon the band is once more heated up, contracts and so repeats the oscillation, which continues as long as the heat energy is supplied. When the electric current is turned off the pendulum dies down.
Studies on the Joule Effect in Rubber. I. The Thermal Effect on Stretched Vulcanized Rubber
Authors: Tanaka Yoshio , Kambara Shū , Fujita Hironosuke
Published: February 2011

The experiments may be summarized as follows: 1. With an increase in the time of cure, the elongation and heating elongation diminish and the Joule effect increases. 2. An increase in the vulcanization coefficient is followed by a decrease in the elongation and heating elongation and an increase in the Joule effect. The increase in the Joule effect, however, has a limit. 3. An organic accelerator reduces the elongation and heating elongation and increases the Joule effect. 4. The greater the degree of mastication the greater the elongation and the heating elongation and the less the Joule effect. 5. By exposure to ultra-violet radiation, the elongation and heating elongation are increased and the Joule effect decreased. 6. A filler increases the heating elongation and decreases the elongation and the Joule effect. Thus samples with relatively high elongations at a definite tension have relatively high heating elongations and low Joule effects. Such specimens seem to have been affected by the disaggregation and depolymerization of the rubber molecules. The effects of the time of cure, mastication, and exposure to ultra-violet radiation prove this fact. Vulcanization increases the Joule effect, but on the other hand, it is accompanied by a disaggregation and depolymerization of the rubber molecules, so the increase in the Joule effect with the progress of vulcanization has a limit. On vulcanization with an accelerator, the combination of sulfur occurs so rapidly that the increase in the Joule effect is predominant. A filler, such as carbon black, behaves only as a diluent of Joule effect. These results lead to the conclusion that the more highly polymerized rubber molecules and their sulfur compounds seem to be the chief factor in the Joule effect of vulcanized rubber.
Viscometric Studies of Rubber Solutions
Authors: Reiner Markus
Published: February 2011

A former communication reported viscometric observations on rubber-toluene solutions in different capillary and rotation viscometers. The consistency curve of solutions from 0.08 to 1.77 per cent concentration starts at the origin as a straight line, inclined at a definite angle until it reaches a certain point a (see Fig. 1). From there it becomes convex toward the stress axis. This convex part extends to an inflection point b where the curve becomes concave up to a point c, where it again becomes a straight line which by extrapolation passes through the origin. The solutions therefore behave as Newtonian liquids between points o and a, and c and ∞. Between point a and c they are non-Newtonian liquids. It was furthermore shown that the “relative” consistency curve, i. e., a curve in which the shearing stress is reduced or the rate of shear increased in proportion to the viscosity of the solvent, is independent of the temperature at which the viscosity measurement is made. From this latter property the conclusion was drawn that the phenomenon of non-Newtonian behavior is a purely mechanical one. It cannot be due, as has been suggested by Staudinger, to a competition between orientation due to laminar flow and rotational diffusion due to Brownian movement because the magnitude of the latter depends on the temperature.
Rubber from Latex Coagulated with Sulfuric Acid
Authors: Martin G. , Davey W. S.
Published: February 2011

The results of tests carried out in the laboratories of the London Advisory Committee show that when sheet rubber is prepared by coagulation of latex with sulfuric acid: (1) Only a trace of free sulfuric acid remains in the dry rubber. (2) The rubber is somewhat easier to manipulate in rubber manufacturing operations than that prepared by coagulating latex with acetic acid. (3) The rubber has satisfactory mechanical properties when vulcanized in rubbers sulfur or accelerator mixings. (4) The rubber ages satisfactorily in rubber-sulfur and accelerator mixings. (5) The use of sulfuric acid would tend to increase the variability in vulcanization of first-grade rubber unless its use became general.
The Specific Gravity of Preserved Latex
Authors: Rhodes Edgar
Published: February 2011

The literature on latex contains a number of references to the specific gravity of fresh latex, but published information on the specific gravity of preserved latex in the condition In which it reaches the consumer appears to be practically non-existent. de Vries and Scholtz and Klotz investigated the specific gravity of undiluted fresh latices of various dry rubber contents, and from their results each deduced the specific gravity of the disperse or rubber phase. The average specific gravity of the rubber globule as deduced by de Vries is 0.914. Scholtz and Klotz's value for the disperse phase is 0.901, which is appreciably lower than that of de Vries. Although. the published literature contains no references to the specific gravity of commercial preserved latex, the Rubber Trade Association of London gives a table of values in its latex contract forms, but details are lacking as to the total number of experimental observations which the table represents. A significant feature is that, by extrapolation of the dry rubber content values to 100 per cent, after the manner of Scholtz and Klotz, the figures obtained for the specific gravity of the rubber disperse phase is 0.912, which agrees fairly well with that of de Vries for fresh latex, and which is considerably higher than that of Scholtz and Klotz. In view of the paucity of information available on the specific gravity of preserved latex, it seemed desirable to obtain additional data and incidentally to make a further check on the published values for the specific gravity of the rubber disperse phase.
Influence of the Gaseous Medium on Hot Vulcanization
Authors: Buizov B. V. , Popova M. K.
Published: February 2011

The results of our previous study of the thermal vulcanization of rubber made it sufficiently clear that during the heating of rubber mixed with sulfur two complex phenomena take place. On the one hand, sulfur interacts with rubber, and on the other, rubber itself undergoes a depolymerization, as well as a polymerization. In reality, however, vulcanization does not proceed under ideal conditions. The rubber and sulfur in the mixture cannot be conceived in an isolated state. On the one hand, the mixture contains the accompanying substances of rubber, such as resins, albumin, etc., whose role in the vulcanization is far from being explained, and on the other hand, the system: rubber + sulfur always exists in some medium. The latter may be either a gaseous or a liquid medium. Hot vulcanization in the industry is most frequently performed in an atmosphere of hot air or in water vapor. We know how great is the difference in the effects of these two conditions. To be sure, the pressure under which the vulcanization takes place is also of importance here; however, the nature of the gaseous medium has evidently a considerable influence on the vulcanization process, which has never been investigated. It seemed to us therefore of interest to investigate this problem, considering the above mentioned two factors, i. e., chemical binding of sulfur and physical changes in the rubber. The previous investigation had shown that the chemical binding of sulfur alone does not explain the nature of vulcanization. Thus, in some cases rubber on heating combines with sulfur, but at the same time disintegrates into a sticky mass and shows no signs of vulcanization with respect to its physico-mechanical properties. Conversely, cases are known where the chemical combination of sulfur proceeds only feebly (and which with chloroprene rubber is entirely unnecessary), whereas the physico-mechanical effects of vulcanization are well pronounced. We therefore undertook an investigation of the processes of chemical combination of sulfur and changes in the solubility of rubber on heating its mixtures with sulfur in atmospheres of various gases. For these vulcanization tests, a mixture of rubber with 7% sulfur and 0.4% magnesium carbonate in the form of sheets of 0.5 mm. thickness containing 6.5% sulfur was used. A piece of such a sheet was wound in one layer around the glass tube A and was then inserted into the test tube B. Gas was slowly conducted at the top of the tube A escaping through the side tube of the test tube B. In the vulcanization tests in alcohol, water and formaldehyde solution, the liquid was poured into the teat tube B, and on evaporation filled the entire space of the tube. All gases were previously dried.
The Specific Gravity of Rubber in Latex
Authors: Vries Ode
Published: February 2011

In a study on the specific gravity of preserved latex, Rhodes comes to the conclusion that the specific gravity of rubber in latex may be estimated at 0.902, and that the figure of 0.914, found by us several years ago, and the figure of 0.912 used as a basis for the tables in the contracts of the Rubber Trade Association of London, are high. Rhodes's figure is based on a large experimental material (852 samples of preserved latex from nine different estates), and agrees well with the estimated figure of 0.901, to which Scholtz and Klotz came from 85 observations on fresh later in Malaya. Our figure was based on a large number of observations on normal estate latex, as well as on latex from specially tapped groups of trees; the difference between 0.902 and 0.914 is too large to be ascribed to experimental errors, though these of necessity are rather high, as the specific gravity of rubber can only be calculated by extrapolation over a zone much greater than the experimental zone itself. It seems of sufficient interest to subject these deviating results to a closer study, as this may, perhaps, throw some further light on a rather complicated problem which is not without practical interest.
Surface Chemistry of Carbon Black. Effect on Vulcanization of Rubber
Authors: Schoenfeld Frank K.
Published: February 2011

In an attempt to develop a theory for the retardation of the rate of cure of rubber stocks by carbon black the adsorption theory is critically reviewed. Experimental evidence is presented that is not readily explainable on the basis of this theory. It is shown that the retarding action of gas black is analogous to the action of organic acid retarders of cure. The mechanism of this action is unknown. Gas black activatedly adsorbs oxygen to form an acid complex that retards the cure of rubber compounds. Organic acids have been obtained from commercial blacks by washing with alkalies.
The Shock-Absorbing Quality of Rubber
Authors: Frumkin L. , Margaritov V.
Published: February 2011

The extensive use of rubber as a shock-absorbing and vibration-absorbing material makes necessary a definite criterion for this property of rubber. In his work on the problem of the shock-absorbing quality of rubber, Morrison states: “To make possible an easy calculation of the rubber buffer, it is necessary to know (1) the permissible working strain at the static loading for a given rubber, (2) the maximum strain permissible at the shock loading, and (3) the energy absorbed by a unit volume of rubber in tile transition from static to shock loading.” Reference to static load is made because, in this calculation, it is necessary to consider those static forces which act on the rubber before shock. The energy absorbed by the rubber in the transition from the static to the shock load is supposed by Morrison to be that energy which is absorbed by the rubber in its deformation by the shock. The question of the energy returned by the rubber in resuming its original form is not considered by him. Vetchinkin in his study of the work of shock-absorbing aeroplane cords fails also to take into consideration the energy returned by the cord on resuming its original form, and bases his calculation only on the absorption by the rubber of a definite quantity of energy during stretching caused by the impact of the aeroplane against the ground. He mentions only casually that, by increasing the preliminary tautness of tile cords, their hysteresis losses of energy are increased. However, such a concept of the work of a rubber shock-absorber seem to us inadequate. In fact, let us distinguish clearly between the work of shock-absorption of rubber and a steel spring. Of course it should be noted that for deformations by the highest possible stresses for rubber and for a steel spring, the former requires more energy per unit of weight. Thus, according to the above quoted paper by Morrison, 1 kg. of rubber absorbs 172 kg. of energy and 1 kg. of steel only 119 kg., i.e., 44% less. According to Geer (cf. “The Reign of Rubber” the difference is many times greater, viz., 10,000 kg. for rubber and 230 kg. for steel.
Semi-Ebonite. Part 1
Authors: Gibbons P. A.
Published: February 2011

Hitherto two products of the reaction between sulfur and rubber have been studied and used commercially, soft rubber and ebonite. Few publications have appeared concerning the products obtained by vulcanization of proportions between 5 and 30 parts of sulfur with 100 parts of rubber. Before the introduction of organic accelerators of vulcanization the coefficient of vulcanization was considered a satisfactory criterion of the quality of soft vulcanized rubber. Mixes of rubber and sulfur vulcanized to a coefficient of more than 3.5 to 4 were usually considered overvulcanized in that experience showed that the optimum properties as regards tensile strength and elongation at rupture occurred at this degree of vulcanization. Semi-ebonites differ from soft rubber and ebonite in as much as they are extremely sensitive to small changes in the time of vulcanization. Their plasticity is such that the velocity of plastic flow just prior to break is relatively great, and thus they may experience a large elongation at constant load. Their plasticity decreases with further vulcanization, in fact, with advance in vulcanization they become almost rigid at room temperature. The decrease in plastic flow is accompanied by an increase in hardness and brittleness and the ultimate stage in the rubber-sulfur reaction, ebonite, is reached.
Fatty Acid Softeners in Rubber Compounding
Authors: Blow C. M. , Garner T. L.
Published: February 2011

1. A method is outlined for the investigation of softeners in rubber compounding; their softening action, their effect on the tensile strength abrasion and flexing properties in a carbon-black tread stock, and their effect on the dispersion of carbon black. 2. The method is applied to the study of a series of fatty acids, their zinc, magnesium, barium salts, and glycerides. 3. Some results are given of the change of abrasion resistance with temperature. 4. A theory of softening action is suggested.
Theory and Application of the Parallel-Plate Plastimeter. Part 2
Authors: Scott J. R.
Published: February 2011

In Part I (loc. cit.) the behavior of a plastic material in the parallel-plate (Williams) plastimeter was studied, and an expression was deduced showing how the rate of decrease in thickness of the sample during compression depends on the volume of the sample, its plastic properties, the compressive load, and the thickness itself. Subsequently, observations were published which showed that the basic principle adopted in this study was incorrect in certain particulars. Peek (loc. cit.), using these observations as a basis, deduced a new expression for the rate of decrease in thickness, though this is too complex for convenient practical use, except in an approximate simplified form. It has now been shown that the expression deduced in Part I, in spite of the inaccurate basis used, is sufficiently near to the truth to render substantially correct the conclusions there stated concerning the plastic properties of unvulcanized rubber stocks. By adopting the more accurate basis used by Peek, moreover, expressions for the rate of decrease in thickness can be deduced for materials showing more complex types of plastic flow than that considered in Part I or by Peek; this had proved impossible by the method previously used. The expression obtained by Peek for the simple type of plastic flow, as well as those now deduced for the more complex types, can be expressed in a form that furnishes a simple and rapid method of examining and analyzing experimental results. As a result of the work described in this paper, it is thus possible to determine, from results obtained with the parallel-plate plastimeter, whether or not a material such as unvulcanized rubber stock exhibits any of the types of plastic flow represented in the general form by Equation 1, and, if so, to find the values of the plastic constants of the material. The procedure is similar to that described in Part I, and consists simply in comparing, by superposition, a set of standard curves drawn on transparent paper with the curve plotted from experimental data. This further development of the method of studying plastic properties by means of the parallel-plate plastimeter should greatly increase its utility as an instrument of research. It has not yet been possible to apply the new method to a systematic study of rubber stocks, but from an examination of existing data it appears that these stocks, tested at 90° C., agree approximately with various forms of the generalized plastic flow equation already referred to.
The Problem of the Evaluation of Reclaimed Rubber by Analytical Methods
Authors: Kirchhof F.
Published: February 2011

Since the problem of the reclaiming of rubber and the increased use of reclaimed rubber in the rubber and cable industries, even in Germany, has again become of importance, interest in methods for the evaluation of reclaimed rubber has naturally increased. It has been recognized in the past that chemical tests can give only a general idea of the approximate composition of a reclaimed rubber, while they show little or nothing about its mechanical properties. Accordingly in most countries, only the most important chemical determinations have been carried out, such as the acetone extract, ash content and sometimes the combined sulfur, while in the case of black reclaimed rubbers, carbon black and sometimes the cellulose present in the rubber, which are determined by difference, are also included. When carbon black is present in high percentage, as is particularly true of modern tire treads, the results of the determination of the quantity of rubber substance are much too high. Therefore the Rubber Control Bureau in Berlin has justifiably required direct information on the carbon black and cellulose in black live-steam reclaimed rubber. The ash and carbon black contents are evident also in the specific gravity of the reclaimed rubber. The specific gravity is most reliably determined with a vulcanized sample or with very thin, smooth sheets by means of the suspension method in zinc chloride solution of suitable concentration.
Research on Modified Rubbers. Part VII. Expanded Chlorinated Rubber
Authors: Schidrowitz P. , Redfarn C. A.
Published: February 2011

In the course of a research on the properties and applications of chlorinated rubber, some trials in connection with moldings were carried out in an ordinary plunger or positive mold of the type which has been used in molding synthetic resin compositions. It was expected that dense but perhaps comparatively flexible moldings would be obtained, and this indeed is the case under certain conditions, e. g., when the mold is allowed to cool under pressure, and the temperature of molding is relatively low. When, however—as is the practice when molding material of the bakelite type—a comparatively high mold temperature (in the neighborhood of 320–350° F.) was employed, and the pressure released while the mold was still hot, it was observed that a remarkable product was obtained of a light, strong, fibrous, cellular character, many times the size of the mold cavity (British Patent 424,561). Expanded chlorinated rubber is more readily obtained from certain commercial brands of chlorinated rubbers than from others, or alternatively, the degree of fluffiness or porosity, strength, and so on may vary according to the brand used, other conditions being equal. After a certain amount of experimentation, however, it was found practicable so to modify conditions of molding that the majority of the brands on the market yielded reasonably satisfactory results (see below).
Rubber in Lubricants
Authors: Stevens H. P. , Stevens W. H. , Donald M. B.
Published: February 2011

As long ago as 1853 it was found that rubber was a suitable addition to oils to improve their lubricating properties. Thus rosin oil was rendered suitable for lubricating machinery, locomotives, wagons, etc., by adding as much of a 1–2 per cent stock solution of rubber in rosin oil to further amounts of oil as deemed suitable. The rubber was cut in thin strips, masticated, and allowed to dissolve in the rosin oil in a hot water bath. A lower temperature could be used by prolonging the time of immersion. A subsequent patent and formulas in a book by Brunner, propose dissolving the rubber in turpentine and adding it to fish and vegetable oils in proportions of about 5–10 per cent. As will be shown later, these proportions are probably too large to be satisfactory, and moreover at that period the recipes were not economical. In 1855 a patent was taken out by Hyde, which in view of our own observations must be regarded as a very remarkable piece of work. After stating that mineral oils for lubricating machinery at temperatures of 600° F. or over require admixture with castor, sperm, or rape oil, he draws attention to the fact that, on keeping at 212° F., or for several days in sunlight, the mineral oils develop a sludge. The addition of rubber to mineral oils, he states, “exerts a most remarkable action in giving permanence to them … and at the same time improves the lubricating or truly oily character of the oil, and the changes under the influence of high heats or the sun's rays are in like manner retarded or prevented for a longer time so as to give a degree of permanency and lubrication such as no other known oil or mixture possesses when tested by lubrication indicators. When more than 2 per cent rubber is added the valuable qualities are in every case impaired, and even less than 1 per cent is usually all that need be combined; 0.5 per cent will give durability and lubrication much beyond that of sperm oil.” He introduced the rubber by suspending it in a cloth bag in the mineral oil at 80–150° F.
Preparation from Rubber of Plastic Materials Suitable for the Manufacture of Films and Threads
Authors: Waterman H. I. , Max C. G. H. , Leenderste J. J.
Published: February 2011

A technical process is described for the preparation of HCl-rubber. Plasticized rubber was used to obtain highly concentrated rubber solutions in C6H6. The HCl-rubber was proved to have properties useful in technical applications as film material. By the method of dry spinning, threads were also obtained. In so far as they were examined, the films and threads were of good quality.
Koroseal, a New Plastic. Some Properties and Uses
Authors: Brous S. L. , Semon W. L.
Published: February 2011

Rubber has found its widest use in industry because its properties can be altered and improved by compounding and cure to give strong, flexible, resilient products which are resistant to abrasion, impervious to fluids, electrically insulating, and relatively inert chemically. For such other desirable characteristics as resistance to oils and solvents, and freedom from attack by air, sunlight, and oxidizing materials, skillful compounding has brought marked improvements, but even better properties are needed to meet the demands of modern industry. The search for synthetic rubbers has been stimulated not merely by the desire for an economically independent source of supply, but also with the hope that there might be obtained materials having properties superior to the natural product. Whitby and Katz (4) have published a comprehensive historical treatise dealing with the development of numerous synthetic rubbers which have appeared in the last few years. It has been believed that linear polymers obtained from dienes hold most promise for the preparation of rubber-like materials. Carothers (1) has studied the relation between the structure of dienes and the types of polymerization products which may be obtained therefrom. On the basis of these data he inferred that, from the standpoint of their polymerization products, the best dienes will be of the type CH2:CXCH:CH2, in which X is an activating group other than alkyl or aryl. In general it has been found that there may be obtained polymerization products with physical properties equal to, or often superior to those of natural rubber, and with marked resistance to the action of solvents and chemicals. Among the many types of organic materials which will polymerize, the vinyl compounds only recently have been modified suitably to yield commercial rubber-like materials.
The Surface Composition of the Rubber Globules in Hevea Latex
Authors: Kemp I. , Twiss D. F.
Published: February 2011

1. A method for the surface analysis of colloidal particles is outlined. 2. The electrophoretic behavior of the protein, resin, and rubber hydrocarbon of the latex of Hevea brasiliensis is described. 3. The electrophoretic behavior of diluted ammonia-preserved plantation latex has been investigated, and it is shown that the amounts of protein and rubber resin adsorbed at the surface of the rubber globule depend on the degree of dilution of the latex and on the pH of the serum. 4. The fractions of the rubber-globule surface covered with protein and with rubber resin are calculated, and their variation with latex-dilution and the pH of the serum is plotted. 5. The rubber globules at pH 8.0 are completely covered with a protein layer, provided the latex is not diluted below 12 per cent of total solids.
Rubber. XVII. Detection of Methylglyoxal and the Ozone Cleavage of Rubber
Authors: Pummerer Rudolf , Matthäus George , Socias-Viñals L.
Published: February 2011

Since the work of Harries, the question whether methylglyoxal is found in the ozone cleavage of rubber has played an important part in explaining the constitution of this hydrocarbon. Since Harries found no methylglyoxal, he assumed a cyclic formation of isopentene, —CH2.C(CH 3):CH.CH2—, residue sand the absence of a corresponding —CH:C(CH3).CH:CH2 end group, which would necessarily yield methylglyoxal. Nevertheless, in view of the probability that a very long open chain is present in the rubber molecule, the necessity again arose of trying to identify methylglyoxal as n product of the ozone cleavage. This involved the problem of detecting extremely small quantities, since the length of the chain might be very great. Provided that no secondary reaction takes place, the yield of methylglyoxal, if formed, should give information about the length of the chains. If, for example, in the cleavage 0.1 per cent of the carbon skeleton were to appear as methylglyoxal, it might be concluded from the three carbon atoms that the chain length is 1000 times greater, viz., 3000 carbon atoms, or 600 isoprene units. These investigations have been undertaken as a conclusion of our earlier work on the ozone cleavage of rubber, in which approximately 90 per cent of the cleavage products were obtained as compounds of the levulinic aldehyde (acid) series.
Isoprene and Rubber. Part 45. Viscosity Measurements of Solutions of Rubber and Hydrorubber in Various Solvents
Authors: Staudinger H. , Mojen H. P.
Published: February 2011

It has been observed many times that solutions of the same concentration of rubber in various solvents show marked differences in viscosity. For example, solutions of rubber in chlorinated solvents such as carbon tetrachloride have higher viscosities than do solutions of the same concentration in benzene or benzine. These differences in viscosity are attributable to the fact that the rubber molecules are solvated in different ways in the various solvents. It may be further assumed that in a particular homologous series of polymers, all members, i. e., substances of both high and low molecular weights, are solvated in the same solvent in the same way, for only in this way is it possible to believe that the specific viscosity of solutions of like concentration increases with increase in the chain length, as has been found to be true of cellulose derivatives. In the previous experiments with squalene and hydrosqualene (cf. preceding article), the constants necessary for calculating molecular weights and chain member indices n were determined. The constants for carbon tetrachloride are higher than those for benzene. In the case of squalene, therefore, as in the case of rubber, carbon tetrachloride gives more viscous solutions than does benzene. If, now, rubbers and hydrorubbers are solvated in the same way as squalene and hydrosqualene, then the same chain lengths of an homologous series of rubber polymers would be obtained by calculations using constants derived from the simple compounds of the chain member index, and from this the degrees of polymerization, are calculated by means of these constants in the formula:
The beta-Modification of Gutta-percha Hydrocarbon
Authors: Pankow Georg W.
Published: February 2011

Clark and later Hopff and von Susich have shown that there are two modifications of gutta-percha hydrocarbon. Hauser and von Susich have studied very carefully the transformation of one modification into the other, and have obtained good x-ray fibre diagrams of both. The identity periods in the direction of elongation were 8.8 A. U. for the α-modification and 4.8 A. U. for the β-modification. The following surprising observation was made: In the fibre diagram of elongated well oriented β-gutta there was found, in addition to the already well known interferences, an interference at a very small angle of deflection in a direction parallel to the fibre axis, corresponding to a lattice plane distance of approximately 115 A. U., i. e., about twenty-four times the identity period. β- Gutta.—Filtered copper radiation, 30 kv., 16 milliamperes. Distance of film 202 millimeters. Screen 0.3 millimeter in diameter. The deep central blackening in Fig. 1 is due to direct radiation which in the photograph in Fig. 2 is intercepted by a lead plate.
The Use of Factice in Rubber Manufacture
Authors: Hurlston E. H.
Published: February 2011

The two main classes of vulcanized oil substitute or factice are heat-cured brown factice and cold-cured white factice. They were both introduced into the rubber industry at about the same time (1846–1847), the former variety by Anderson and the latter by Parkes. It has been stated (Twiss, Trans. Inst. Rubber Ind., 7, 234 (1931)) that Parkes first opened a proofing factory at Birmingham but that the business was shortly afterwards absorbed by Chas. Macintosh & Co. and transferred to Manchester. This probably dates the commencement of the use of white factice in proofings. The early history of the development of the use of brown factice on a works scale is more obscure. As the name implies, these vulcanized oils were used in the first place as ingredients which could economically substitute part of the crude rubber content of mixings, but as time went on it became apparent to compounders that these materials possessed intrinsic properties which made them almost indispensable in certain mixings, both for ease of manufacture and for high quality of the resultant article. The utility of factices in the general rubber trade is therefore in many respects analogous to that of reclaimed rubbers.
The Pendulum as a Source of Energy for Plasticity Measurements
Authors: Williams Ira
Published: February 2011

ADVANCEMENT in methods for studying the consistency of rubber during the last 10 years has been confined largely to various modifications of previous tests and to better interpretation of the data obtained. The extrusion plastometer introduced by Marzetti (11) has been modified by Behre (1) to provide a battery of instruments, by Dillon and Johnston (5) to provide more simple apparatus capable of operating at increased rates of shear, and by Dillon (4) to provide an instrument for rapid control work. The parallel-plate plastometer (16) has received numerous modifications of form. DeVries (2) modified the plates to provide a constant area of contact with the rubber. This modification was used by van Rossem and van der Meyden (14) who stressed the necessity of following the elastic recovery as well as the rate of compression. Karrer (8) pointed out the need for controlling the time factor during compression and recovery and has described an instrument (9) with which each measurement requires about 30 seconds. The balance plastometer, which employs parallel plates, was described by Hoekstra (7) and is well adapted to following the elastic recovery after the rubber has been compressed under any conditions of thickness and time. A parallel-plate instrument with interchangeable parts to provide various methods of applying pressure and following recovery was described by Lefeaditis (10). The relation between compression and the extent of recovery has been considered by Dillon (3), who concluded that the measurement of either the compression or the elastic recovery as obtained with the usual parallel-plate plastometer was sufficient if the comparison was confined to a number of batches of a given stock or type of rubber. He also pointed out that elastic recovery depends on the speed of the previous deformation. Hoekstra (6), after considering some of the factors involved in plastic flow, concluded that elastic recovery should be measured only after compression of a rubber to the fixed thickness. The general usefulness of the parallel-plate plastometer has been greatly increased by the mathematical treatment of Peek (13) and Scott (15). A third type of plastometer, consisting of a disk which rotates in compressed rubber while the resistance to shear is measured, has been described by Mooney (12).