bluuebunny/crossref_metadata_2025 huggingface dataset:
A Contribution to the Problem of the Impregnability of Cord Threads with Rubber
Authors: Hauser E. A. , Hünemörder M.
Published: February 2011

A review of the different methods employed today for preparing the carcass of tires will distinguish two main principles of working: 1. The direct treatment of dry fabrics (cord fabrics, weftless cords) with raw rubber compounds either by simply applying skim coats or by combining this operation with frictioning rubber on by calendering. 2. The pre-impregnation of the fabric or weftless cord either with a rubber solution or with latex. Latterly the direct application of latex (natural rubber milk) has found more and more favor in this industry also, and it is certainly possible to use latex for impregnation, instead of rubber solutions or cements. This is evident from the practice of the natives of Brazil in making their waterproof fabrics. The second category of processes may accordingly be divided into two subgroups: those which work with benzine rubber solutions and those which use latex. While comparatively simple tests enable us to find out with the greatest ease why the use of cord fabrics or weftless cords has other advantages over the use of closely woven fabrics, in addition to the higher degree of elasticity already referred to, it is much more difficult to decide whether it is more advantageous to use dry fabrics previously impregnated with benzine rubber solutions or fabrics that have been pre-treated with latex.
The Structure of Rubber and the Mechanism of Elastic Stretching
Authors: Mack Edward
Published: February 2011

A theory of the mechanism of elastic stretch in rubber is described. It is christened a “hydrogen-evaporation-condensation” mechanism. In an attempt to develop a unified theory of rubber behavior, some of the more important properties of the various forms of rubber are discussed, from the point of view of strict adherence to the principles of geometry and of structural organic chemistry. Among the topics discussed are: shape of the rubber molecule, the work of stretching rubber, the shape of the stress-strain curve, heat effects in rubber (including the Joule effect), Staudinger's hydrogenated rubber, factors controlling cis and trans addition, x-ray diffraction pattern, properties of synthetic rubbers, inversion, and sluggishness.
Vulcanization and Stress-Strain Behavior of Sol, Gel, and Total Rubber Hydrocarbon
Authors: Smith W. Harold , Holt William L.
Published: February 2011

The existence and significance of a soluble and an insoluble fraction in rubber hydrocarbon and the proportions in which they occur have long been the subject of conflicting reports, which have been summarized in a previous paper. They were the basis of a two-phase theory of rubber structure proposed by Fessenden. The history of the subject need not be reviewed here. Early knowledge of it was summarized by Engler and Herbst in 1887 and an excellent historical treatment has been given by Whitby. The differing solubilities and other characteristics of the two fractions suggested a study of their behavior when vulcanized. A sufficient quantity of rubber hydrocarbon for the purpose was purified and separated into the soluble and insoluble fractions by extraction with ethyl ether; suitable compounds of each were mixed and vulcanized, and comparative tests made.
The Influence of Certain Colored Substances on the Autoöxidation of Balata and of Rubber
Authors: Bondy H. F.
Published: February 2011

Thanks to the numerous investigations of Moureu and Dufraisse, a large number of substances are now known which retard the autoöxidation of oxidizable substances. These retarding substances were given the name of antioxygens by the authors. Dufraisse and his collaborators have studied, with special attention to rubber, a certain number of antioxygens which greatly retard autoöxidation and the changes which take place during aging. In a preceding work I showed, by a study of different portions of the acetone extract of rubber, that certain substances exercise an antioxygenic effect which is the greater the more highly colored they are. The question then arose whether, in addition to antioxygens which act chemically, there may not be colored substances capable of retarding the autoöxidation of rubber by physical means by absorbing active luminous radiation. I thus ignored completely spontaneous autoöxidation, which is quite a different phenomenon from the one I did investigate. In the work referred to above, some experiments on colored substances were described which showed, for example, that azobenzene and α-benzeneazo-β-naphthylamine had a very great antioxygenic action, whereas alizarin and carotene were almost inactive. The present work will show whether colored substances are capable, by purely physical means, of preventing the autoöxidation of rubber and of substances allied to rubber, such as balata and gutta-percha.
The Effect of Surface-Active Substances and Electrolytes upon the Crystallization of Sulfur from Rubber Solutions
Authors: Dogadkin B. , Margolina J.
Published: February 2011

1. If surface-active substances are added directly to rubber or to the solvent e. g., fatty acids and their salts, naphthenic acids, thionaphthenic acids, etc., there is after evaporation of the solvent a marked reduction in the size of the sulfur crystals which are formed in the rubber films. 2. The size of the sulfur crystals depends upon the concentration of the surface-active substances in the rubber solution. The precipitate with the greatest degree of dispersion is obtained at a definite optimum degree of concentration, e. g., one per cent of calcium oleate and fish oil, based on the rubber. A higher concentration of surface-active substances leads to an increase in the size of the sulfur crystals. 3. The dispersing action of capillary-active substances decreases with the age of rubber solutions, but this was not observed alter storage of the mixtures and films themselves. 4. Rubber softeners in the molecules of which there are no polar groups (e. g., vaseline oil) show no dispersing action. 5. Some electrolytes, added to the rubber solution, likewise promote the dispersion of sulfur in the form of small crystals. 6. The dispersing action of surface-active substances and electrolytes disappears with an increase in the temperature at which the film is formed (up to 70° C.). The sulfur is precipitated in the form of monoclinic dendrites and rhombic crystals.
The Measurement of the Plasticity of Rubber. A Reply to Dillon and Johnston
Authors: Behre J.
Published: February 2011

In a recent contribution Dillon and Johnston commence by criticizing my explanation of the dependence of the plasticity upon the pressure. They state that the shear dv/dx is dependent upon the shearing stress F and the slippage S, and that the pressure is not a criterion of the flow conditions of rubber. This is certainly true, and I have never maintained that the pressure is a criterion of the plasticity, but I certainly do use, as these authors also propose, .the shear as a measure of the degree of plasticity, that is, the volume extruded in fifteen minutes. Naturally this depends upon the pressure or its component, the shearing stress. The only difference in the methods of measurement seems to me to lie in the magnitude of the shear and in the pressure applied. I do not believe that this leads to results which differ essentially, but differ only in their order of magnitude. Furthermore, Dillon and Johnston believe that when I quoted my earlier publication an error was made. This is not the case, for the graph in the work by Bachmann, Behre, and Blankenstein shows clearly the dependence of the work expended upon the degree of plasticity for both cold and hot mastication, and also shows that in order to reach a given plasticity, the amount of energy consumed during hot mastication is less than during cold mastication. The graph shows at the same time, however, that hot mastication makes rubber soft more quickly, both with respect to the time and the energy consumed, than does cold mastication. In view of the fact that I was not so clear in the manner of expressing myself as the facts required, these statements may give rise to misunderstandings, and therefore I feel that I should explain this point in more detail. I meant to imply nothing more than that the rubber which was masticated on rolls at a temperature of 65° C., and which was also tested at this temperature, showed higher plasticity values than did rubber which was masticated and tested at 18° C. In spite of this, Dillon and Johnston, in checking this experiment, milled rubber at 73° and 112° C. and made their measurements in each case at 100° C.
Diffusion of Water through Organic Insulating Materials
Authors: Herrmann D. B.
Published: February 2011

Water has remarkable penetrating power. No organic substance is known to be entirely impervious to it. The life of plants and animals may be said to depend on the diffusion of water through their cell walls, and it is a familiar fact that the water which permeates the human body forms its largest single component. Water passes through materials often considered water-proof such as rubber, asphalts, and waxes. In the Bell System a number of organic materials are used as insulations which often are exposed to moisture. Though the actual quantity of water which diffuses through most organic substances is small, this small amount becomes important in condensers, coils, and terminal boxes and other apparatus which must be protected over a period of years. One of the methods used to evaluate insulations which are to be exposed to moisture is the measurement of the quantity of water absorbed. Such measurements do not always give a complete picture of water-proofing characteristics, since a considerable amount of water may diffuse through a layer of material into some interior space and only a small amount remain absorbed in the outer layer. Differences in molecular structure, phase relationships, and crystalline state may play important roles in diffusion, and often the absorption of water does not appear to be the principal controlling factor.
Research on Modified Rubbers. Part VI. The Oxidation of Rubber Solutions with Gaseous Oxygen in Presence of Catalysts
Authors: Bloomfield G. F. , Farmer E. H.
Published: February 2011

In a previous study of the oxidation of rubber, the oxidative action of peracetic acid, or mixtures behaving substantially as such, was examined (Bloomfield and Farmer, J. Soc. Chem Ind., 53, 121T(1934)). The results then obtained pointed to a course of reaction characterized by (a) additive attack at the unsaturated centers of the rubber molecules, resulting in the production of a high degree of hydroxylation, and (b) extensive molecular degradation with liberation of carbon dioxide (see also Mair and Todd, J. Chem. Soc., 1932, 386). In an extension of this work, attempts have been made to prepare peracetic acid by means other than the interaction of hydrogen peroxide with acetic acid or anhydride, and among other methods the autoxidation of acetaldehyde at low temperatures in the presence of cobalt acetate as catalyst (G P. 269,937; U.S.P. 1,179,121) was tried. Though peracetic acid was successfully obtained in this way in fair yield, an attempt to prepare it on a larger scale resulted in a violent explosion. In order to eliminate the danger arising from an accumulation of peracetic acid, oxygen was led into a chloroform solution of rubber containing a cobalt acetate catalyst together with acetaldehyde, with the hope that in this way peracetic acid might be formed in situ; at low temperatures (−20° to 0°) no reaction occurred, but on submitting such a solution to the action of oxygen at temperatures above 30° a very rapid reduction of viscosity set in, and the solution yielded a viscous gum containing a little oxygen. Now Stevens and his co-workers have recently shown that rubber solutions readily undergo oxidation by gaseous oxygen when certain catalysts (notably the heavy metal salts of organic acids) are present. It immediately became apparent that the oxidation phenomenon just described affords the basis for a greatly accelerated process of this type, the acceleration being due to the presence of acetaldehyde. It was thought desirable at this stage to investigate broadly the entire subject of oxidation of rubber solutions in the presence of catalysts of this nature, and a study has accordingly been made of the oxygen absorption of rubber solutions containing different catalysts, the oxygen intake being measured by the contraction occurring in a closed system containing oxygen, the latter being kept constantly circulating by means of a pump of the pattern designed by Finch (J. Chem. Soc., 1925, 2464). Since it was found that a considerable quantity of carbon dioxide was formed during oxidations of this type, the circulating gases were passed through a trap containing baryta water, and at any stage of the oxidation the amount of carbon dioxide formed could be ascertained by removing the contents of the trap, filtering off the precipitated barium carbonate, and determining the barium as sulfate.
The Hydrogenation-Cracking of Rubber
Authors: Cawley C. M. , King J. G.
Published: February 2011

Rubber is amenable to treatment by the process of hydrogenation-cracking at a pressure of 200 atmospheres of hydrogen and at temperatures above 360°. The rubber is suitably treated in a continuous plant in the form of a solution containing 50% of rubber and 50% of an oil boiling above 200° obtained by the hydrogenation of rubber. At a reaction temperature of 450–480°, and in the presence of a molybdenum catalyst, a high yield of spirit (boiling up to 200°) is obtained. In one passage of the raw material over the catalyst the yield is from 40 to 60% by weight of the rubber solution, the remainder being oil (53 to 18%) and gaseous hydrocarbons. The crude product is a pale yellow mobile oil, and the fraction boiling below 200° a water-clear spirit. The latter contains aromatic 15, unsaturated 1.5, and saturated hydrocarbons 83.5%. It therefore requires only very little refining to make it stable on storage. As the reaction temperature is lowered, the yield of spirit decreases, while that of high-boiling oil increases. The high-boiling oil also becomes more viscous. Thus at 370° the yields, as percentages by weight of the rubber solution, are: spirit boiling up to 200° 10.6%, and oil boiling above 200° 87.6%. The latter is distilled to produce 46.7% of Diesel oil, 21.5% of lubricating oil, and 19.4% of residue. The greater part of the Diesel oil and the high-boiling residue is required to prepare rubber solution for use as the raw material. Rubber can therefore be treated by a hydrogenation-cracking process to yield either motor spirit alone or motor spirit, fuel oil, and lubricating oil, depending on the temperature of treatment. As a commercial project the rubber treated would require to be surplus production available to the process at a much lower cost than that of rubber purchased in the normal market.
The Chlorination of Disaggregated Rubber
Authors: Buizov B. V. , Molodenskii V. S. , Mikhailov N. I.
Published: February 2011

1. Methods of production of chemical derivatives of rubber must be based upon the use of old, disaggregated raw material. The application of this principle to the production of chlorinated rubber has been firmly established, and thus offers the possibility, upon the basis of our first experiments, of developing methods for the production of chlorinated rubber. 2. The investigation of the process of chlorination of rubber disaggregated by means of copper compounds completely supports the authors' point of view concerning the character of the action of copper compounds on the rubber. The authors view this action as a disaggregation of the rubber, which destroys its elastic structure and transforms the rubber compounds into forms which are chemically reactive. 3. The process of chlorination of disaggregated rubber by the means of copper compounds proves the authors' hypothesis about the mechanism of this disaggregation, which leads to the formation of cyclic compounds of rubber.
Refractive Index of Rubber
Authors: McPherson Archibald T. , Cummings Arthur D.
Published: February 2011

This paper presents an exploratory study of the refractive index of rubber. Previous observations on the refractive index of rubber have been, for the most part, restricted to transparent samples. In the present investigation, however, by using reflected light rather than light at grazing incidence, it was found possible to extend the range of measurements to rubber samples that were somewhat dark in color or that were very nearly opaque. Such being the case, determinations of refractive index were made not only on translucent samples of unvulcanized or soft vulcanized rubber, but also on binary mixtures of rubber and different compounding materials, and on compounds of rubber and sulfur containing 0 to 19 per cent of sulfur and covering the range from soft to semi-hard rubber. Different samples of unvulcanized Hevea rubber, of plantation origin, all showed approximately the same refractive index, irrespective of considerable variations in the nonhydrocarbon components. The index was not appreciably altered by the amount of mastication which rubber ordinarily receives in processing and mixing with compounding ingredients. Mixtures of rubber with substances insoluble in it showed the same index as the rubber itself, while mixtures with soluble substances differed in index from rubber by an amount which depended upon the index of the substance and the amount in solution. Measurements of refractive index, therefore, afford a means of measuring the solubility of substances in rubber and were employed for determinations of the solubility of sulfur and of a common antioxidant, phenyl-β-naphthylamine. Sulfur in combination with rubber had a relatively greater effect on the refractive index than did sulfur in solution. For vulcanized rubber-sulfur compounds in the soft-rubber range, the refractive index was a simple linear function of the percentage of sulfur and also of the temperature. Preliminary measurements on vulcanized compounds in the hard-rubber range indicate that the change in physical properties of rubber-sulfur compounds from soft to hard was accompanied by a decrease in the slope of the curve relating refractive index to temperature.
The Coefficient of Friction of Rubber
Authors: Derieux J. B.
Published: February 2011

Coefficient of friction is defined as the ratio of the force of friction to the load producing it. The accepted laws of the coefficient of friction are: 1. It is independent of the area of the surface in contact. 2. It is independent of the load applied. 3. It is independent of the velocity, at low values. 4. The static value is greater than the kinetic, i. e., it is greater at the beginning of motion than after motion has been established. The accompanying data will show that every one of these accepted laws are violated by rubber. The following values for area were obtained by varying the pressure in an automobile tire in place on an automobile on concrete.
The Specific Gravity of Preserved Latex
Authors: Rhodes Edgar
Published: February 2011

The Journal of the Rubber Research Institute of Malaya, 5, 234 (1934), contained a paper on the specific gravity of preserved latex written by the writer of this note. The paper has recently been made the subject of constructive comment by de Vries. As a result of the examination of 852 samples of preserved latex, a specific gravity/dry rubber content table was derived for preserved natural latices, and the dry rubber content range covered was wide enough to include natural unconcentrated latex in all the phases in which it is likely to be required by or become available to the commercial user. By the unavoidable expedient of extrapolation from the experimental results, a value of 0.902 was also derived for the specific gravity of the rubber phase in preserved latex. This value was in good agreement with the figure of 0.901 obtained by Scholtz and Klotz for “rubber” in fresh latex. On the other hand, de Vries, working with fresh latex had previously derived a value of 0.914 for the specific gravity of the rubber phase, and the specific gravity table used by the Rubber Trade Association of London for preserved latex gives on straight line extrapolation a value of 0.912. It seemed that the value indicated by the work of De Vries and that deduced from the table of the Rubber Trade Association were probably rather high, and certain experiments with centrifugal concentrated and centrifugal concentrate-skim mixtures were cited which provided some confirmatory evidence of this conclusion.
Heats of Reaction of the System Rubber-Sulfur
Authors: McPherson Archibald T. , Bekkedahl Norman
Published: February 2011

PREVIOUS investigators have employed two methods for determining the heat effects when rubber is vulcanized. In one method the heats of vulcanization are found by subtracting the heats of combustion of vulcanized rubber—sulfur compounds from the heats of combustion of the corresponding mixtures of rubber and sulfur before vulcanization (1, 10, 11). This method is limited in precision by reason of the fact that the differences thus obtained are at most only a few per cent of the measured heath of combustion. The other method, which has been used previously, involves the determination of the temperature rise which occurs when mixtures of rubber and sulfur are vulcanized. This method has, for the most part, been used for relative measurements, but Blake (2) has recently employed it for quantitative determinations of the heats of reaction of rubber with proportions of sulfur up to about 8 per cent by weight. Recently Daynes (7) has employed a similar method for measurements over a wider range of composition. This investigation was undertaken for the purpose of measuring the heath of reaction of rubber with different percentages of sulfur over the entire range of composition in which combination takes place. The study was exploratory in character, the aim being to make the measurements by direct means with emphasis on simplicity rather than refinement of calorimetric procedure.
Dispersion of Channel Gas Black in Rubber. Effect of Stearic Acid and Other So-called Dispersing Agents
Authors: Park C. R. , Morris V. N.
Published: February 2011

THE completeness of wetting of carbon black by rubber, the consequent state of dispersion of the black, and the effect of the surface forces in the development of reënforcement of the rubber have been the subjects of much deliberation and experimentation. Of special interest has been the effect of stearic acid upon the dispersing power of rubber for carbon black. On the basis of Green's observation (6) that the dispersion of zinc oxide which had previously flocculated in kerosene resulted in a pronounced softening of the mixture, Goodwin and Park (5) concluded that stearic acid has little effect upon the dispersion of carbon black in rubber. They pointed out that stearic acid has a slight softening action in uncured stock and in cured stock containing no zinc oxide, and that the addition of fatty acid to a stock containing no zinc oxide affects its physical properties adversely. Although they considered that these facts furnished slight indications of a dispersing effect by the stearic acid, these authors offered no convincing evidence of the dispersing effect of stearic acid on carbon black in rubber. For various reasons, including the fact that the plasticity of uncured black stocks is not materially affected by the presence of zinc stearate, Goodwin and Park also concluded that zinc stearate is not a dispersing agent for blacks. In fact, they postulated that the effect of zinc stearate, if any, is to decrease the wetting of the black by the medium and hence to cause flocculation. Since the combined addition of zinc oxide and stearic acid to a rubber-sulfur mix results in an improvement in properties, these investigators were finally led to the conclusion that the principal effect of these soap-forming agents in a carbon black stock is on the curing properties of the rubber itself rather than on the dispersion of the black.
The Physico-Chemical Properties of Latex and Their Significance in Manufacture
Authors: Madge E. W.
Published: February 2011

The first physico-chemical property of latex to be discussed is that of viscosity, if latex can be said to have a viscosity. As will be seen later, this property is so important in many manufacturing processes, such as extrusion, dipping, and centrifuging that the fundamentals must be understood. Latex, as is well known, is a suspension of irregularly shaped particles, many pear-shaped, in an aqueous medium which itself contains an appreciable proportion of other dissolved and suspended matter. These particles, according to present ideas, are surrounded by a strong adsorption layer, which influences very considerably the properties of the latex. As a result of its composite structure, latex and more particularly latex compounds have rather interesting properties. From the point of view that latex creams under gravity, that the particle carries an appreciable electric charge, and depends partly on this for its stability, and that the swelling of the actual particle in water is very small, it may be called hydrophobic. On the other hand, in view of its behavior with respect to dehydrating agents, the manner in which it forms aqueous voluminous gels, and more particularly in its reaction to shearing forces, latex may be classed as hydrophilic. Its hydrophilic character is conditioned by the material adsorbed on the surface of the particles and is more pronounced in compounded and treated latices.
Heat Changes in the Vulcanization of Rubber. I. Qualitative Tests on a Comparative Basis
Authors: Horie Hukio , Monikawa Kikuo
Published: February 2011

As a preliminary test of the quantitative determination of the thermal changes in the vulcanization of rubber by sulfur, 100 parts of raw, resin-free and pure rubber were compounded with 5, 10, 15, and 20 parts sulfur, respectively, and vulcanized in a thermostat at 160 ± 0.2° C. The change in temperature was noted by reading a thermometer, the mercury bulb of which was inserted in the center of the sample, and the heating curves thus obtained were compared with the analytical results of free and combined sulfur determinations. 1. There was practically no exothermic or endothermic reaction in the samples without sulfur. 2. Those samples containing sulfur had but one maximum exothermic point, and the maximum temperatures decreased in the order: raw rubber system > resin-free rubber system > pure rubber system. 3. The times required to reach the maximum temperature decreased in the order: pure rubber system > raw rubber system > resin-free rubber system. 4. The time required to reach the maximum temperature was shortened by increasing the proportion of sulfur added, except for the 10 per cent mixtures. 5. The presence of nitrogenous substances was detrimental to the vulcanization process, in the reactions where less than 5 per cent of combined sulfur was obtained, but their presence was necessary to obtain more combined sulfur. 6. The agent which accelerates the vulcanization reaction seems to be the nitrogenous substances.
The Raman Spectrum of Rubber
Authors: Gehman S. D.
Published: February 2011

It has been previously reported that the Raman effect is exhibited by rubber as a continuous scattering together with the presence of broad bands (Franklin and Laird, Phys. Rev., 36, 147 (1930); Busse, J. Phys. Chem., 36, 2862 (1932)). Busse attributed this result to the viscosity of the solutions or to the possibility that the rubber groups respond to a wide range of frequencies. However, viscous solutions of polysterol in carbon tetrachloride give a line spectrum (Signer and Weiler, Helv. Chim. Acta, 15, 649 (1932)). As to the second explanation, this does not seem to be the nature of the Raman effect (Bär, Helv. Phys. Acta, 4, 369 (1931); Bär, Z. Physik, 79, 455 (1932)). The Raman effect has been investigated extensively for terpenes other than rubber. The bands and continuous background for rubber appear to be due to fluorescence of impurities, oxidation products, or the rubber hydrocarbon. The acetone extract of rubber is fluorescent as observed in ultra-violet light. The intensity of the bands and background for rubber decreases as the rubber is purified. However, acetone extraction and two diffusions with ethyl ether did not remove the fluorescence entirely, as could be seen by examination between complementary light filters. Some of the background is undoubtedly unmodified radiation, that is, Tyndall scattering by the colloidal structure and by motes. This can be reduced by a monochromatic light filter.
Studies on the Acetone Extraction of Raw Rubber
Authors: Endô Hidemaro
Published: February 2011

(1) For the determination of the saponification value of the acetone extract, 20 cc. 0.2 N alcoholic potash is added to the extract and the flask is heated on a water bath for 60 minutes. It is then titrated with 0.1 N HCl solution, using phenolphthalein as indicator. (2) When the saponification values of the acetone extracts of 8, 16, and 24 hours are compared, the saponification value of the 8 hour extract is seen to be high, while those of 16 and 24 hour extracts are low. This indicates (a) that the 8 hour extract contains a higher percentage of saponifiable matter than the 16 and 24 hour extracts; (b) the quantity of rubber hydrocarbon which is dissolved in the acetone extract increases with increasing time of extraction, and (c) the acid value of the acetone extract decreases during the period of extraction from 16 to 24 hours. (3) Regarding the saponification values (R) of the acetone extracts of 8, 16, and 24 hours, similar remarks may be made as in (2) above.
Research on Modified Rubbers. Part V. Technological Properties of Chlorinated Rubbers from Latex
Authors: Schidrowitz P.
Published: February 2011

Bloomfield and Farmer, in a paper on “The Preparation of Chlorinated Rubbers from Latex” (J. Soc. Chem. Ind., 53, 43 (1934); Rubber Chem. and Tech., 7, 320 (1934)) have described the chief chemical properties of the products prepared by them. The object of the present paper is to describe briefly some characteristics of these products from the technological standpoint. It will be remembered that, although Bloomfield and Farmer were able to prepare a soluble chlorohydrin from one batch of latex, all other batches yielded insoluble products, although some modification of this insolubility was attained by the addition of serum from the satisfactory latex to those latices which were refractory in this regard. Moreover, the latex which yielded soluble products at first, subsequently no longer did so. Similarly the products from the initially satisfactory latex, at first soluble, underwent a gradual change, becoming less and less soluble. The technical examination of the chlorohydrin from latex therefore proved to be difficult. However, as it was thought possible that a method producing substances of more or less consistent composition and solubility might be later developed, the soluble product referred to was examined from the point of view of ascertaining its suitability as a basis for lacquers, moldings, plastic masses and films.
APPENDIX The Composition of Some Chlorinated Rubbers
Authors: Bloomfield G. F. , Farmer E. H. , Miller C. H.
Published: February 2011

With a view to obtaining some information which might throw light on the nature of the expansion process and on certain differences observed in the readiness with which various chlorinated rubbers undergo expansion, the compositions of a number of chlorinated rubbers have been determined. For these determinations the commercial materials were dissolved in benzene and filtered free from insoluble matter, the solutions being then concentrated to small bulk under reduced pressure; the chlorinated rubbers were precipitated by the addition of methyl alcohol, washed and ground with chilled methyl alcohol, and finally maintained at 50–60° under high vacuum until constant weight was attained. The results of the various determinations are expressed in the table below.
Rubbone
Authors: Stevens H. P. , Stevens W. H.
Published: February 2011

Of all the reactions which natural rubber undergoes, oxidation next to vulcanization, may be said to rank in the first place. For not only does the life and usefulness of all raw and vulcanized rubber depend on the course of this reaction, but attempts to create useful oxides may be regarded as based on the same reaction. It has already been shown that, by the catalytic oxidation of rubber, solutions of greatly reduced viscosity and/or increased concentration are obtainable. Thus, a 50 per cent solution of rubber which will flow at normal temperatures can be made by incorporating 2.5 per cent of cobalt linoleate on the mill, subsequently “letting down” in white spirit or other solvent by means of an internal type of mixer. The mechanism of the oxidation of rubber is a complex and still incompletely solved problem, but a reasonably acceptable explanation of this reduction in viscosity is that it is due to a disaggregation of the rubber micelle, whereby a very small amount of chemically combined oxygen is enabled to effect a very large physical change in the character of the colloid. This change is promoted by catalysts, such as the ordinary paint driers, and there appears to exist an analogy between the drying of paint and the disaggregation of rubber solutions, but it is interesting to note that whereas copper soaps have substantially no effect on the drying of linseed oil, they do reduce the viscosity of rubber solutions appreciably. Solutions of rubber containing catalysts have been “blown” by bubbling air, oxygen or ozonized air through them while maintained at raised temperatures by suitable means. The experiments covered a great variety of conditions, including different solvents, different types and concentrations of rubber and catalyst, mixed catalysts and a variety of temperatures and blowing conditions. It was found that under suitable conditions the oxidation of the rubber could be taken to a stage where the cobalt linoleate itself became oxidized and was precipitated from the solution. After filtering, the resulting solutions were evaporated to yield an oxidized rubber resin. A standard procedure has been developed for the production of this rubber resin, or “Rubbone” as it is conveniently termed, as follows. A solution of milled blanket crepe in white spirit is made by dissolving 20 parts by weight of rubber in 80 parts by weight of solvent, adding 0.5 part of cobalt linoleate, and aerating at 80°C. until a sample drawn off from the bulk shows a quick separation of sediment and a clear supernatant solution of the resin. The solution is clarified by “tanking” or centrifuging and is then distilled by steam or in vacuo to separate the resin.
Properties of Latex-Insulated Wire
Authors: McGavack J.
Published: February 2011

In 1863 latex was proposed and actually used to insulate wire. Siemens had the happy thought of employing this material to cover conductors and actually went so far as to obtain patent protection for his idea. From that time until recently, there has been practically nothing accomplished in the manner directed by Siemens. In fact, no commercial insulation material resulted from the idea proposed in the middle of the nineteenth century. It is not hard to see why such a plausible idea was abandoned. The insulation obtained in the manner disclosed by Siemens was not nearly as good as the other known methods for insulating wire. Conductors covered by the method then proposed could not be used in water or where any moisture was present. There were too many water-soluble materials in the latex; and as no method was known at that time to remove these materials from latex without coagulating the latex itself, no further development was accomplished.
Isoprene and Rubber. Part 44. Viscosity Measurements of Squalene and Hydrosqualene Solutions
Authors: Staudinger H. , Mojen H. P.
Published: February 2011

The physical properties of highly polymerized substances, which are composed of fiber molecules, depend on the lengths of the chains of these fiber molecules. Thus tensile strength, elasticity, tendency to swell in solvents, and above all viscosity, are dependent on the length of chain of the particular substance. Among the substances, the properties of which vary thus, are rubber, gutta-percha, and balata. Since the length of fiber molecules can vary within wide limits, such physical properties as those mentioned above show wide variations in the case of rubber, gutta-percha, and balata. This is evident for example by a comparison of the properties of unmasticated rubber, which consists of long fiber molecules of a degree of polymerization of 2000, with the properties of masticated rubber, the greatly dissociated molecules of which have a degree of polymerization of only 500. The determination of the length of the fiber molecules is therefore of great importance in the case of highly polymerized substances. It has already been proved in past experiments with members of a series of homologous polymers, i. e., of substances the macromolecules of which have the same basic structure and differ only in length, that the molecular weights can be determined from viscosity measurements. This determination is based on the fact that there is a general relation between the specific viscosity and the length of the dissolved molecules, which can be expressed by the formula:
The Effect of Pigment Particle Size on Some Physical Properties of Rubber Compounds
Authors: Barnett C. E.
Published: February 2011

The importance of flow in rubber on the reinforcing properties of pigmented systems has been emphasized by Park. He suggests that: (1) in the presence of a finely divided pigment, the flow which occurs when a piece of rubber is stretched takes place in the capillary spaces between the pigment particles; (2) some modification of the laws of liquid flow may govern the behavior of rubber with reference to pigments embedded in it, and (3) the forces causing increased stiffness in pigmented rubber compounds are similar to those causing increased resistance to flow of liquids iii tubes of capillary dimensions. Thus increasing fineness of subdivision and the resulting fineness of capillary spaces between the particles should be accompanied by an increase in reinforcing properties. It would be desirable to study the actual stresses around pigment particles in rubber under strain, but so far no suitable microscopic set-up has beem devised. A few years ago the writer, resorting to analogies, measured the strains and stresses around large particles with the assumption that the strains would be relatively the same with small particles. For this study, holes of the desired size and shape were cut in strips of calendered but uncured rubber and fitted with pieces of an uncured semihard rubber compound. After vulcanization squares were marked on the tensile sheets as shown in Fig. 1.
Heat Generation and Anisotropy of Rubber Compounds in the Flexometer
Authors: Havenhill R. S.
Published: February 2011

Data have been presented to show that it is possible for rubber compounds when tested in the flexometer to exhibit simultaneously a plastic flow in one direction, and a marked stiffening in another direction, resulting from the elimination of plastic flow by rapid flexing. Both effects are shown to be due mainly to heat generation or temperature effects. The rate of heat generation depends in part on the anisotropy of the rubber, which is much greater than is indicated by some of the ordinary physical tests such as tensile strength, resistance to tearing and to abrasion. The theory that the degree of anisotropy is influenced by the shape and orientation of the pigment particles and of the anisotropy of the rubber itself has been in a measure experimentally verified.
Bacterial Decomposition of the Rubber in Hevea Latex
Authors: Spence D. , Van Niel C. B.
Published: February 2011

A RECENT communication (6) has shown by several different means that rubber present in the living plant actually disappears under seasonal and other conditions in the life of the plant, and that it can, therefore, no longer be regarded as an excretory product of metabolism of no physiological value to the plant. The results recorded were obtained in a study of the rubber content of Parthenium argentatum, but they will undoubtedly be found to hold for Hevea brasiliensis when suitable methods of investigation are developed for the latter. The importance of these findings in relation to the economic development of rubber is obvious and far-reaching. They have already been applied in the cultural development and exploitation of Parthenium argentatum. On the scientific side they suggest a more intimate study of the behavior of the rubber hydrocarbon towards oxidation-reduction processes occurring within the living plant and to the effect of such agencies on the rubber itself in vitro. That rubber is readily attacked by oxidizing agents in general is now well known. But even the classical researches of Harries on the products of decomposition of the rubber hydrocarbon by means of ozone (1) have thrown little light on the ways and means by which the rubber in the plant is first produced and thereafter broken down and utilized in its cycle of yearly development. This is not surprising when we consider the reagents heretofore employed and the drastic character of the decompositions effected by them.
A New Rubber Particle Count in Hevea Latex
Authors: Langeland Earle E.
Published: February 2011

SO MUCH confusion has grown up in the literature concerning the number of rubber particles in Hevea latex that at the present time there exists a thousandfold error in the currently published reports (1, 3, 8) of the one original determination of this number. Harries (4), Hauser (5), and Noble (8), each reporting the original work of Henri (6), give a count of 50,000,000 particles per cubic centimeter of latex, Harries not specifying the concentration, while Hauser and Noble indicate it to have been 8.7 per cent solids. On the other hand, Dubosc and Luttringer (2), also reporting the work of Henri, record a count of 50,000,000 particles per cubic millimeter in latex of unspecified concentration. The original paper of Henri (6) reported that he had found an average of 50,000,000 particles per cubic millimeter of latex having a specific gravity of 0.973 and containing 8.7 grams of solids per 100 cc. Preliminary counts undertaken by the author with a view to developing a rapid microscopic method for the determination of the dry rubber content of latex indicated that the results of Henri were considerably low. Since the number of microscopically visible particles is a fundamental property of latex, it was felt that a redetermination of this number would be of value.
Determination of Guanidines in Rubber Stocks and Consumption of Guanidines during Cure
Authors: Humphrey Bingham J.
Published: February 2011

QUANTITATIVE determinations of various accelerators that may be present in vulcanized rubber stocks are necessary, not only for fundamental investigations into the mechanism of acceleration, but also for routine control analyses and the examination of unknown stocks. The determination of any organic material in vulcanized rubber stocks is beset with numerous difficulties, however, and reliable methods are scarce. For accelerators, the only ones described in the literature are the now generally employed copper oleate method for mercaptobenzothiazole and an extension of Callan and Strafford's (1) picric acid method for guanidines, both described by Wistinghausen (2). Using these two procedures, Wistinghausen made an extended investigation of the consumption of mercaptobenzothiazole and of diphenylguanidine (D. P. G.) during cure. Considerable difficulty was encountered in this laboratory in the use of Wistinghausen's method. Especially with di-o-tolylguanidine (D. O. T. G.) stocks, the results were highly variable and the proportion of guanidine recovered seemed to be much smaller than that recovered by Wistinghausen from similar stocks. As a test of both the method and the technic, an uncured di-o-tolylguanidine tread stock was analyzed, since it was believed that, in this case, an effective procedure should account for substantially all of the guanidine put into the stock. The result was that little or no more guanidine was recovered from the uncured stock than from the same stock at an optimum cure. Guanidine recoveries from either one ranged from 30 to 50 per cent.
The Natural Stabilizers of Latex
Authors: Stevens W. H.
Published: February 2011

The paucity of information regarding the properties of natural rubber and allied latices, other than Hevea Braziliensis, is surprising. While great attention has been paid to fresh and preserved Hevea latex, little or nothing appears to have been done recently with other rubber or rubber-like (e. g., gutta, balata, etc.) latices. Indeed, many authors of papers on rubber latex preface their articles with a statement that only Hevea latex will be considered, other latices being of no commercial interest. It is likely, however, that a careful scientific examination of latices of botanical origin other than Hevea would yield much information of practical importance to the application of Hevea latex, although these latices may not be obtainable at present in commercial quantities. For instance, the fact that certain of these latices require no preservative indicates that they contain a natural stabilizer greatly superior to any substance occurring naturally in Hevea latex, or used in its industrial applications. The identification and application to Hevea of such natural stabilizers represents, therefore, an important technical research. Though many references to latices other than Hevea are to be found in the literature, these are mostly somewhat old, and more often than not predate the advent of the rubber plantation industry, while more recently the attention so strongly focused on Hevea latex has caused the latices of other botanical origin to be entirely neglected. The data given below for Abiarana gutta-percha latex may, therefore, be of some interest.
Consumers' Crude Rubber Requirements
Authors: Sackett George A.
Published: February 2011

In this brief summary of requirements, much has been left unsaid. It is difficult to be specific, for the requirements of the rubber manufacturing industry vary widely. It is hoped, however, that this presentation will focus some attention on the subject, and that eventually a more definite idea of the requirements of the various consumers will be presented so that plans of research in rubber-producing parts of the world can be made to develop the products needed by the consumer. This would also aid in the development of closer contact by both producer and consumer, which is desirable in any industry. The formulas suggested are open to criticism and it is hoped that if those suggested are not adopted as standard, others more generally accepted will be evolved so that there may be a universal agreement on the method of testing certain properties of rubber. It may be argued that a rubber which combined all the properties mentioned would be ideal, but it is well to set up an ideal to strive for, so that through the collaboration of producer and consumer, it may perhaps be realized.