bluuebunny/crossref_metadata_2025 huggingface dataset:
X-Ray Investigations on Rubber
Authors: Ott Emil
Published: February 2011

During some earlier x-ray investigations on cre^pe rubber, it was observed that the originally translucent sample became more and more milky at the spot where the x-rays passed the material. The sample was the same as described in an earlier paper. This rubber gave a distinct x-ray pattern during the first exposure, but, although the lines did not change their position, they became increasingly sharper with each exposure; simultaneously the opaqueness of the milky spot increased. The increase of sharpness of the originally broad lines represents, of course, increase in particle size; but evidently also the increasing cloudiness of the cre^pe rubber shows progressing crystallization.
The Viscosity of Rubber Solutions under Influence of Benzoyl Peroxide. A Contribution to Methods for Determining Inorganic Fillers, Etc., in Rubber Mixtures
Authors: Fromandi G.
Published: February 2011

IN THE determination of mineral and certain organic substances in rubber mixtures by the aid of disintegration with paraffin oil or anisol, difficulties occur during filtration in the presence of golden antimony which require the use of a centrifuge, since the relatively high viscosity of the colloid system does not permit a sufficiently high rate of sedimentation for practical purposes. Some investigations of rubber mixtures containing golden antimony, in which for certain reasons the use of a centrifuge was impracticable, necessitated the development of a method which would obviate the use of a centrifuge. By means of decalin (decahydronaphthalene) and benzoyl peroxide it was possible to so control the ordinary disintegration that the sedimentation of the filler and antimony particles increased to such an extent that filtration was no longer difficult.
Natural and Synthetic Rubber. VI. the Pyrolysis of Natural Rubber in the Presence of Metallic Oxides
Authors: Midgley Thomas , Henne Albert L.
Published: February 2011

Pale crepe rubber pyrolyzed in the presence of zinc oxide or magnesium oxide gives the same decomposition products as in the absence of the oxides, but in different proportions. This modification is attributed to an action of the oxides upon the double bonds of the rubber molecule.
The World's Rubber Supplies
Authors: Rae George
Published: February 2011

Until the beginning of the present century, the world's supplies of crude rubber were obtained from trees and shrubs growing naturally in the equatorial regions of the earth, mainly in South and Central America and Central Africa; this rubber is generally known as wild rubber. Today, owing to the rapid increase in the production of cultivated rubber, the output of wild rubber is sufficient to supply only about 3 per cent of the world's requirements. In 1900 the total output of wild rubber amounted to about 54,000 tons, but this included considerable quantities of moisture and other impurities, and the dry rubber equivalent probably did not exceed 40,000 tons, while plantation output was nil. In 1929, the latest year for which complete statistics are available, the output of wild rubber was only 26,000 tons, while the output of cultivated rubber amounted to 821,000 tons. Cultivated or plantation rubber, as it is more generally called, is subdivided into estate and native rubber. Estate rubber is produced on estates owned and managed by Europeans, and on estates over 100 acres owned by Asiatics. Native rubber is produced on holdings under 100 acres. (Some of the larger native holdings in Sumatra and Dutch Bornea may be greater than 100 acres.)
The Lipin of Hevea Latex
Authors: Rhodes E. , Bishop R. O.
Published: February 2011

A body having properties and composition similar to those of the plant lipin complexes described by various authors has been isolated from Hevea latex.
Observations on the Effect on Vulcanization of the Lipin of Hevea Latex
Authors: Eaton B. J. , Rhodes E. , Bishop R. O.
Published: February 2011

Some preliminary vulcanization tests which have been made with the Hevea lipin (vide Quarterly Journal of the Rubber Research Institute of Malaya, 2, 125 (1930)) are described.
Isoprene and Rubber. Part 32.The Constitution of Rubber
Authors: Staudinger H.
Published: February 2011

1. The establishment of the molecular size of high molecular compounds which are composed of fiber molecules by the end-group method of determination is only possible if homologous polymeric series of similar type are concerned. 2. The end-group method assures reliable values with molecules up to a molecular weight of 1000 at the highest. With higher molecular products, like cellulose and rubber, the method is inexact. 3. The molecular weight of rubber and balata may be determined by viscosity determinations in the following two ways: (a) M=ηsp/cKm (b) M=Kc.Kcm. The constants Km and Kcm are determined with low molecular decomposition products. 4. Rubber and balata are composed of fiber molecules, which in one dimension have the magnitude of colloidal particles and in both the others, the dimensions of low molecular substances. 5. In highly viscous rubber solutions, there is the characteristic state of solution. As a result, the sphere of action of the dissolved molecule is greater than the volume at the disposal of the solution. This solution is midway between a true solution and a gel, and is therefore designated as a gel solution. It occurs only with high molecular substances, and is characteristic of them. 6. The readiness with which rubber solutions vary is explained by the fact that the rubber molecules are very sensitive to chemical influences and to changes in temperature as a result of the position of the double bonds. This sensitivity varies with the length of the molecules.
Rubber. Part XII. Levulinic Acid Peroxide from Rubber
Authors: Pummerer Rudolf , Ebermayer George , Gerlach Karl
Published: February 2011

The so-called levulinic aldehyde diperoxide, which has already been described by Harries and which we call more correctly “levulinic acid peroxide,” is formed not only by “over-ozonization” of the rubber ozonide, but always when rubber ozonide solutions are kept sealed up for a long time, for example, in an ice box. While frequently at first there is only a very slight precipitation after the ozonization, in the course of eight to fourteen days it increases greatly. After filtering and after washing with ether, the yield may reach from 15–20% of the carbon skeleton of the rubber, and it is therefore a decomposition product of the rubber ozonide, which is formed in the neutral medium, perhaps by traces of moisture. Since it is also especially easy to isolate beforehand and is a suitable weighing substance for levulinic acid, we have attempted to confirm for ourselves that the substance still contains the unchanged carbon skeleton of levulinic acid.
The Effect of Grit upon the Stress and Strain Properties of a Carbon Black Stock
Authors: Kearsley E. P. W. , Park C. R.
Published: February 2011

Numerous papers have appeared from time to time dealing with the detection of grit in rubber pigments, in practically all of which it has been tacitly assumed that grit seriously impairs the quality of the pigment. Rubber articles, especially tire treads, made with pigments containing even small proportions of gritty material are considered inferior, and specifications covering grit are usually quite rigid. Pigment manufacturers have gone to great lengths to produce grit-free pigments, and the resulting product undoubtedly justifies the additional manufacturing care exercised. The importance of differentiating between actual grit and agglomerates of pigment particles which are subsequently dispersed during mixing operations has been pointed out by Murphy (Trans. Inst. Rubber Industry, 2, 100 (1926)), and various methods of accurately determining true grit have been suggested by this same author, by Gallie and Porritt (Trans. Inst. Rubber Industry, 2, 116 (1926)); by Esch (GummiZtg., 41, 82 (1926)), by Evers (Kautschuk, 1927, 70) and by others. The difficulty with which carbon black may be elutriated has limited the employment of such an agency in determining the proportion of grit present in it, and the laboratory has been confined to the use of screens of various size apertures for this purpose.
Some Properties of Carbon Black. I. Adsorption
Authors: Wiegand W. B. , Snyder J. W.
Published: February 2011

The diphenylguanidine (O. P. G.) adsorption test correlates well (0.8) with rubber-curing behavior in organically accelerated mixings, in respect to the broad classes of carbon black, but only moderately (0.4) in respect to standard rubber carbon black. The D. P. G. or similar adsorption test, although correlating better than the volatile-matter test, is therefore not capable of predicting with precision the rubber-compounding behavior of standard (rubber) carbon black. Carbon-black adsorption is much more marked in the alkaline than in the acid range. While heat-activated carbon blacks show marked increase in D. P. G. adsorption, heat-deactivated carbon blacks show greatly reduced alkaline and slightly increased acid adsorption, 2 which probably explains the anomalous iodine adsorption of heated blacks noted in the literature. In litharge compounds without added fatty acid, high-adsorption blacks spoil the cure by removing the fatty acid present in the rubber. Heat-deactivated carbon black leaves the cure relatively unaffected. In litharge compounds containing an excess of added fatty acid, however, both heat-deactivated and high-adsorption blacks improve the cure, doubtless through removal of excess acid. In general, for carbon black-litharge compounds a low-adsorption carbon black is preferable because it permits a minimum dosage of fatty acid.
Recovery of Rubber and Cotton from Uncured Tire Ply Scrap. Extraction Process
Authors: Powell Charles S.
Published: February 2011

A new method for reclaiming uncured tire ply scrap is described. This is an application of the familiar solvent-extraction process. It possesses several advantages over the other methods of separating the rubber and cotton fabric in the scrap, particularly from the standpoint of waste of materials, for both the cotton and the rubber are completely reclaimed without deterioration. If the process is to have wide application, however, means must be devised for utilizing the dilute rubber cement produced. THE utilization of tire trims has always been a difficult problem. Composed of uncured rubber and long staple cotton, their value is considerable. Certain quantities, after being broken down on a mill, can be used in bead covers, flaps, shoe soles, and mats without detrimental effects. The Dunlop Rubber Company (2) has been granted a patent covering a composition of uncured ply scrap, ground scrap, etc., to be used in the manufacture of objects of fibrous rubber.
Graphical Tensile-Testing Machine for Rubber Threads
Authors: Hahn S. H. , Dieterich E. O.
Published: February 2011

AMONG the many types of physical testing equipment which have been designed for or applied to the needs of the rubber industry, there has never appeared an entirely satisfactory graphical machine for performing tensile tests on small rubber samples, such as the threads and tapes used in making golf balls and elastic fabrics and cords. None of the common machines can be applied directly to the testing of single threads, and even tests on pieces of dumbbell shape are quite unsatisfactory, largely because the standard machines are comparatively insensitive at low elongations and tensions and also because they depend on the personal accuracy of an operator to observe several points along the stress-strain curve. The Schopper ring test is not entirely successful for tests on threads. Accordingly it appeared that such tests on light rubber threads could best be made on a curve-drawing machine, designed and constructed especially for the purpose. In many cases, the use of any other machine would have been impossible because frequent tests had to be run on single, cut threads from factory production and on samples taken from storage or from woven fabric.
The Determination of the Chloroform-Soluble Substance of Vulcanized Rubber
Authors: Minatani Iwasaburo , Aoe Ichiro
Published: February 2011

The determination of the chloroform-soluble substances in vulcanized rubber is a valuable clue to the content of certain ingredients, such as asphalt, mineral rubber, pitch, etc., for vulcanized rubber containing these ingredients shows a greater proportion of chloroform-soluble substance. Vulcanized rubber containing none of these materials generally has a chloroform extract of 0.3–3.0 per cent. It is generally high in uncured rubber, but even optimum and highly vulcanized rubber contains some chloroform-soluble substance. This fact was pointed out by Tuttle and Weber, in the Official method edited by the German Industrial Material Committee, and in a report of the Joint Rubber Insulation Committee (Ind. Eng. Chem., 9, 310; 6, 80). The object of the experiments was to determine the chemical nature of the chloroform-soluble substances in vulcanized rubber, as it is not known whether they are hydrocarbons or their derivatives, and whether they have the same composition at the different stages of vulcanization. As the chloroform-soluble substance in vulcanized rubber containing none of the softeners mentioned bove is obtainable only in small quantities, special attention was given in compounding of the rubber, and the following formula was used:
Isoprene and Rubber. Part 25. The Homologous Polymeric Hydrorubbers
Authors: Staudinger H.
Published: February 2011

Harries states in his studies on natural and artificial kinds of rubber “It would be of great importance to be able to carry out the reduction of rubber, because hydrorubber probably distills unchanged in a high vacuum, and therefore its constitution could be determined for certain.” This reduction was studied simultaneously by Pummerer and Burkard and by Staudinger and Fritschi. It is necessary to refer again to these works in order to correct earlier data on the basis of more recent experimental knowledge.
Value of Softeners in Tread Stock
Authors: DeFrance M. J. , Krantz W. J.
Published: February 2011

In view of these results, it may be concluded that in this tread stock the minimum amount of pine tar or mineral rubber commensurate with good factory processing is desirable if the maximum abrasion resistance for a given cost is to be obtained. This means that softeners which are effective, as such, in smaller amounts than those available at present should find a use in tread compounding. Stearic acid should be held to a ratio of approximately 4 parts per 100 of rubber. Most of the laboratory tests give indications in the same direction as the road wear, but none coincide exactly.
Influence of Physical Properties of Carbon Black on Its Tinting Strength
Authors: Kearsley E. P. W. , Roberts G. L.
Published: February 2011

1—Tinting strength is not an absolute function of particle. 2—No direct ratio exists between tinting strength and hiding power. 3—The thickness of the film of adsorbed gases on the carbon-black particles determines the tinting characteristics. 4—The volatile matter present and the oil-absorption properties serve as a measure of the relative thickness of such films. 5—The completeness with which these gases are displaced materially affects the tinting strength. 6—Complete displacement is only possible when the inter-facial tension produced by the dispersing medium at the surface of the carbon-black particle is sufficiently low to assure complete wetting.
Permeability of Rubber to Air. II: Effect of Stretch, Thickness, Milling, Compounding Ingredients, Kind of Crude Rubber, and Temperature of Vulcanization
Authors: Morris V. N.
Published: February 2011

The permeability of rubber membranes was found to be approximately inversely proportional to thickness. The recently developed “super” automobile inner tubes are therefore undoubtedly better air containers than the ordinary tubes of smaller gage. Most of the increase in permeability resulting from stretch can be accounted for by the decrease in thickness accompanying stretch. Pure-gum stocks made from various commonly used plantation rubbers did not vary much in permeability. A stock made from a wild rubber, caucho ball, had a somewhat lower permeability. Milling on a steam-heated mill was found not to change permeability appreciably. The early stages of milling on a cold mill reduced the permeability of a stock slightly. The temperature of vulcanization seemed to have no influence on permeability, provided the test slabs were cured to the same state. It may be concluded, therefore, that the recent trend towards higher temperatures of cure for inner tubes has not adversely affected their air-retaining capacities. None of the various softeners or other organic materials tried was found to effect any appreciable decrease in the permeability of a rubber stock The results indicate that permeability is roughly proportional to the volume of rubber hydrocarbon present in a stock. The nature of the principal compounding ingredient used in a stock does have some influence on permeability, however Clay, channel black, and blanc fixe are among the compounding ingredients having the most beneficial influence on permeability. Experiments with stocks containing various quantities of zinc oxide indicate that permeability varies inversely with the volume of pigment present. From the standpoint of the air-retaining capacity, the loading of inner-tube stocks with pigments is therefore desirable.
New Autographic Machine for Testing Tensile Properties of Rubber
Authors: Albertoni George J.
Published: February 2011

A description is given of a testing machine for the measurement of the tensile strength of materials having considerable deformation, such as rubber. A stress-strain recording device is described in which the strain recorded responds to the separation between a pair of independently movable pointers which may be made to follow the separation of two marks, spaced upon the sample before insertion in the machine. Mechanical means are also described to correct for variations in the test-piece cross section, and to produce equal chart displacements for equal angular deviations of the inclination balance.
Microturbidimeter for Determination of Rubber Content of Latex
Authors: Gehman S. D. , Ward J. S.
Published: February 2011

It is desirable to devise a method for determining the dry rubber content of latex which will be both more rapid than the two trial coagulation methods and more precise than the hydrometric method. The turbidity of latex, depending upon the volumetric number and size of the suspended rubber particles, offers a satisfactory criterion for the determination of the rubber content of latex. A microturbidimeter, herein described, has been adapted to such determinations. It permits more rapid determinations of the rubber content than the two trial coagulation methods. Its precision is less than the lengthy trial coagulation method, involving coagulation, creping, and drying, but is probably greater than that of the shortened trial coagulation method involving only coagulation and creping. Its precision is approximately 1 per cent rubber in 35 per cent latex. The turbidity of latex obeys the turbidity-dilution law for rubber-content values less than 15 per cent. The use of color filters, transmitting the shorter wave lengths of light, minimizes the effects of a difference in the effective mean particle size of different kinds of latex.
The Determination of the Size, Form, and Solvation of Macromolecules
Authors: Schulz Günter Viktor
Published: February 2011

As has been shown in earlier work, the molecular weight M of particles and the specific solvation volume s (the volume which corresponds to 1 gram of dissolved substance plus the solvent bound to it in the system) in a lyophilic colloid solution can be determined by means of osmotic measurements. This depends upon the fact that the osmotic pressure of such solutions is expressed by the equation: On the other hand, according to Eisenschitz, the relative viscosity of a suspension of elongated particles is represented by the equation: where l is the length, and d is the short axis of the particles. If it could be proved that the specific solvation volume s has the same value by the two methods of measurement, then the absolute dimensions of the particles in a colloidal solution could be obtained from parallel osmotic and viscosimetric measurements. This can now be done. On the assumption that newly dissolved rubber molecules are fiber molecules and the s values from osmotic and viscosimetric measurements are the same, all factors on the right side of equation (2) can be obtained from osmotic and roentgenographic data. Consequently the ηrel value can be calculated in advance. The values thus calculated agree extremely well with the experimental values of the relative viscosity.
Verification of the Specific Gravity of Rubber before and after Its Vulcanization
Authors: Kreps B. S.
Published: February 2011

1. Every hot vulcanization of a rubber compound leads to a volume decrease of the vulcanized material, or to an increase of its specific gravity. 2. The increase of the specific gravity of a rubber system depends directly on the condensation of rubber only, and does not depend on fillers. 3. The extent of the increase of the specific gravity of a vulcanized material is proportional to the quantity of rubber in the compound and to the degree of vulcanization. 4. Active fillers, as ZnO, and accelerators can influence the growth of the specific gravity of a vulcanized compound as agents promoting vulcanization; hence carbon black, contrary to Ditmar's opinion, can hardly contribute to condensation.
Roentgenographic Examination of μ-Polychloroprene (CH2:CClCH:CH2)x
Authors: Garbsch P. , Susich G. v.
Published: February 2011

μ-Polychloroprene (polymeric 2-chloro-1 ,3-butadiene or “Duprene”), recently described by Carothers, Williams, Coffins and Kirby, shows in the unstretched state an amorphous x-ray picture and when stretched a well-defined fiber diagram. Since a crystallization and parallel orientation of this kind upon stretching had not been observed previously in any natural or artificial product other than natural rubbers (smoked sheet, latex film, amorphous crepes), although some of these products may be highly elastic and may even split apart into fibers in the cold, the x-ray diagram makes possible a rapid and certain identification of the μ-polychloroprene.
Acetylene Polymers and Their Derivatives. III. The Addition of Hydrogen Chloride to Vinylacetylene
Authors: Carothers Wallace H. , Berchet Gerard J. , Collins Arnold M.
Published: February 2011

The results of experiments on the action of aqueous hydrogen chloride on vinylacetylene are described. The initial step consists In 1,4 addition and the primary product is chloro-4-butadiene-1,2, This readily undergoes isomerization, yielding chloroprene, which always constitutes a part of the reaction product. When cuprous chloride is present in the reaction mixture the isomerization proceeds more rapidly and no chloro-4-butadiene-1,2 is found in the reaction product. When sufficient hydrogen chloride is present the reaction proceeds further, yielding dichloro-2,4-butene-2.
Measuring Microscope for Rubber Specimens
Authors: Lofton R. E.
Published: February 2011

A microscope provided with a six-times micrometer eyepiece and objectives of 32 and 48 mm. focal length is suitable for measuring the cross-sectional dimensions of rubber test specimens. The width of specimens is usually greater than that of the die with which they were cut. The thickness of soft compounds as determined by the microscope is greater than that indicated by a gage of the plunger type. A MICROSCOPE of low power, equipped with a micrometer eyepiece, affords a convenient and practical means for accurately measuring the dimensions of rubber test specimens, and at the same time permits the inspection of specimens for defects. The equipment here described was designed particularly for measuring the width of the familiar dumb-bell shaped tensile test strips. At the present time no convenient and accurate gage is available for this purpose, and it is common practice to assume that the width of the specimen is the same as the die with which it was cut. The same equipment has been found satisfactory for determining the thickness of test strips, and is generally applicable for the measurement of dimensions up to about 6.4 mm. (0.25 inch). This use of the microscope embodies no original features. The method and equipment, however, are here described in some detail, since they may be of interest to investigators who may have occasion to make accurate mechanical measurements on rubber.
The Chemical Resistance of Rubber as an Engineering Material
Authors: Fritz H. E. , Hoover J. R.
Published: February 2011

Contrasting strangely with the liveliness exhibited in the physical reactions of rubber, we find in respect to chemical reactions a distinct lethargy, an inertia, which renders the material of unique value in certain engineering applications. It is apparent, when the manifold uses of rubber as a chemically resistant material are studied, that its value in the majority of cases depends not only upon the chemical inertia and peculiar physical properties of the basic substance, but also upon the fact that this basic substance has been intelligently combined with a variety of other materials. Too much emphasis cannot be placed upon the fact that rubber compounds are designed for specific uses; and that they can be bonded to many other structural materials with practically integral adhesion. This paper is a summary of data pertinent to the application of rubber compounds in resisting corrosion or avoiding contamination. Such data should be of service to engineers who are confronted with the selection of materials for uses where there are problems involving corrosion of equipment or contamination of product. While unvulcanized fine Para and pale crepe rubbers have been, and to a very limited extent are still, used as corrosion-resistant linings in chemical storage, process or transportation equipment, the great bulk of rubber applied to chemical service is vulcanized. The present discussion will be limited therefore to vulcanized rubber. When the conditions of service are accurately known by the manufacturer, vulcanized rubber can be compounded to resist actual immersion for long periods in any of the inorganic acids except those of strong oxidizing character. The same is true. of nearly all inorganic salts and alkalies, and to a somewhat more limited extent of commercial organic materials.
Atmospheric Cracks on Unstretched Rubber Products. Their Origin and Prevention
Authors: Merz Otto
Published: February 2011

It was proved that in collapsible boat material, in contrast to pure rubber mixtures: 1. Cracks occur without stretching, and 2. Cracking takes place sooner in sunlight than in the shade. Various possible ways are discussed for painting collapsible boat materials to protect them from cracking. The requisites for a serviceable paint are summarized. Waxes, rubber products, oil varnishes, and cellulose nitrate lacquers appear to be unsuitable because of various faults. Only combinations of paints of suitable composition meet these requirements. The poor resistance to weathering of collapsible boat materials can be overcome by immediately painting the new material.
The Influence of Temperature on the Evolution of Hydrogen Sulfide from Vulcanized Rubber
Authors: Cummings A. D.
Published: February 2011

This paper presents the results of measurements of the evolution of hydrogen sulfide from rubber-sulfur compounds heated at various temperatures. Determination of the amount of hydrogen sulfide produced under different conditions was used to measure the degree of decomposition of the rubber. Two types of experiments were carried out: (1) Samples of vulcanized rubber containing 8 to 32 per cent sulfur were heated for 8-hour intervals at 13 temperatures between 105° and 265° C., and (2) samples having sulfur contents of 4, 10, 18, and 32 per cent were maintained for about 200 hours at constant temperature, one set of specimens at 136° and another group at 220° C. These measurements of deterioration were undertaken in connection with an investigation on the electrical properties of vulcanized rubber at relatively high temperatures. During these experiments, samples of rubber-sulfur compounds had been subjected to a wide range of temperatures. Time of exposure to each temperature had been about eight hours. The purpose of the present work was to determine when the sulfur content of a specimen had changed sufficiently to affect its dielectric constant and power factor by a measurable amount. In order to approximate the conditions under which the electrical tests were made, it was necessary to determine the amount of decomposition when rubber vulcanized with 8 to 32 per cent sulfur was heated for successive intervals of eight hours each at temperatures changed in unequal steps from 105° to 265° C. To make this information more complete and to obtain additional data which could be compared with previous investigations, the work was extended to include determinations of the loss of hydrogen sulfide from vulcanized rubber heated for a long time at constant temperature. The electrical properties of the whole series of rubber-sulfur compounds is the subject of a separate investigation at this bureau, and will be reported in another paper.
The Thermal Decomposition of Natural and Artificial Rubber in the Presence of Aluminum Chloride
Authors: Zelinsky N. D. , Koslow N. S.
Published: February 2011

The numerous published works on reactions taking place under the influence of aluminum chloride show more and more what an important part the latter plays in organic chemistry. During recent years experiments by one of the present authors and his collaborators have shown that aluminum chloride acts as a catalyst in the thermal decomposition of complex homogeneous substances, that it lowers the temperature of the decomposition and that it makes this decomposition take place in a well-defined way. This phenomenon consists of a hydrogenation by hydrogen of the unsaturated fragments of the decomposition, where the hydrogen is removed from the condensed mass of organic material. For example, a complete series of hydrocarbons of different composition and constitution are obtained by the decomposition of such substances as cholesterol, oleic acid, and abietic acid, in addition to phytosterols (betulin). These investigations showed that the chemical nature of the hydrocarbons formed differs according to the original substance. Cholesterol, for example, yields, in addition to gaseous and easily volatile paraffins, a preponderance of benzine hydrocarbons in which cyclic forms (cyclohexane and cyclopentane derivatives) predominate. Therefore benzine from cholesterol resembles benzine from crude Caucasian oil. The properties of the hydrocarbons from the higher fractions are likewise different from those of the substances named above.
Fundamentals in the Problem of Resistance to Deterioration
Authors: Taylor Hugh S.
Published: February 2011

The problem of control in processes of deterioration is the problem of control of the speed of chemical reactions. The fundamental reactions in deterioration are oxidation processes involving oxygen, steam or other less universal oxidizing agents as well as reactions of polymerization, decomposition, and depolymerization. Heat and light, ionization, pressure, and the presence of accelerating agents are the important factors which influence the speed of such processes and are thus of major importance in a discussion of the fundamentals of the problem. Control of deterioration is the inverse of the historical occupation of the chemist. Since al-chemical times his prime concern has been the promotion of chemical reactions. A belated attention to the problem of preserving his synthetic achievements is not, however, without its own peculiar scientific interest and practical significance.
The Production of Isoprene from Rubber
Authors: Bassett H. Ll , Williams H. G.
Published: February 2011

For more than a century, researches have been carried out on the distillation of rubber, and the general nature of the products—isoprene, terpenes, and higher terpene compounds—has long been known, but comparatively little work ha been done on the effect of variations in the conditions of distillation, and in particular on the maximum possible yield of isoprene. Williams (Phil. Trans., 150, 241 (1860)), using an iron retort and distilling rubber at a relatively low temperature, obtained some 5% of crude isoprene b. p. 37–44°. Fischer and Harries (Ber., 35, 2156 (1902)) showed that when rubber is distilled at 0.25 mm., less than 1% of isoprene is obtained, and Staudinger and Fritschi (Helv. Chim. Acta, 5, 785 (1922)), working at 0.1–0.3 mm. and 275–320°, obtained 3.1%. These two results are not quite consistent, but they tend to show that a low pressure militates against a high yield of isoprene.
The Surface Affinity of Rubber for a Filler
Authors: Vellinger E.
Published: February 2011

It is known that there is a relation between the mechanical properties of rubber and the nature of the, filler or pigment which is incorporated in it. It has been proved that certain fillers have the property of improving considerably the characteristic mechanical properties of rubber. Thus zinc oxide has proved to be a better reinforcing agent than some substances with a finer particle size. Lithopone, with a fineness which is of the same order of magnitude as that of zinc oxide, has no reinforcing action whatever. Gas black has the most powerful action known. Moreover all reinforcing fillers are very good absorbents. On the contrary inert fillers arc of little account from this point of view. The phenomena of adsorption seem then to play an important part in the reinforcing action of fillers, and consequently substances with strong surface activity are adsorbed by these fillers.
Studies on the Nature of the Action of Organic Accelerators of Vulcanization. The Action of Organic Accelerators on Rubber Sols I–III
Authors: Shimada Keiichi
Published: February 2011

While there is a difference of opinion as to the exact mechanism involved, it is generally agreed that the action of organic accelerators in hastening the vulcanization process is usually attributed to the conversion of the sulfur into an active form, probably through the intermediate formation of a compound capable of yielding “nascent” sulfur. But some workers, (Ames, J. Soc. Chem. Ind., 43, 117T (1924); Kirchhof, Kolloid-Z.,, 14, 35 (1914); Twiss, J. Soc. Chem. Ind., 35, 782 (1917); Ditmar, Z. angew. Chem., 34, 465 (1921)) have suggested that the action of organic accelerators might be on the rubber hydrocarbon itself. This theory has not been generally developed, though it has received some small amount of evidence through the works of Le Blanc and Kröger (Z. Elektrochem., 27, 335 (1921)) and Naunton (J. Soc. Chem. Ind., 44, 243T (1925)). These investigators found that the viscosity of rubber solutions decreased with the introduction of an organic accelerator, and referred this phenomenon as a “depolymerization” of rubber. These observations possibly suggest that the influence of accelerators is exerted upon the rubber and constitute the only direct evidence in favor of this view.
Factors Affecting Rate of Vulcanization of Chloroprene Plastic Polymers
Authors: Bridgwater E. R. , Krismann E. H.
Published: February 2011

These tests have clearly shown the desirability of compounding this polymer with zinc oxide, magnesia, and rosin, and have demonstrated that these three ingredients when used together have a desirable effect that cannot be obtained with, or even predicted from, the results obtained with any one of them alone or the combination of any two of them. It has been shown further that, although it is possible to obtain good vulcanized products from this polymer without the addition of sulfur, a great increase in the rate of cure and substantial improvement in physical properties of vulcanized products result from the use of as little as 0.5 per cent of sulfur on the weight of the polymer. it is further shown that pine tar and rosin oil may be substituted for rosin but that they are somewhat less efficacious. The authors postulate that the value of rosin, pine tar, and rosin oil is probably due to the organic acids that they contain. Coumarone resin and brown factice are shown to be desirable compounding ingredients for chloroprene polymers.
Studies in the Interfacial Relationships between Rubber and Fillers. I. The Tear-Resistance of Vulcanized Rubber
Authors: Lefcaditis G. , Cotton F. H.
Published: February 2011

1. The importance of tear-resistance as a criterion of the interfacial relationship between rubber and its fillers has been emphasized. 2. Existing methods of determining resistance to tear in vulcanized rubber have been described, and subjected to a critical examination. 3. The disadvantages peculiar to each of the above methods have been discussed, and experiments whereby it was aimed to overcome these sources of errors are described. 4. A new method of determining resistance to tear has been evolved, whereby the tearability is measured in terms of the mean of the initial and final loads required to tear a 4-mm. length of a butt-ended test-piece prepared by punching with a standard dumb-bell die from the inner disc of a 6-mm. ring test-piece. Figures are given to indicate the consistency of the results.
The Separation and Identification of Sol Rubber Hydrocarbons
Authors: Midgley Thomas , Henne Albert L.
Published: February 2011

(1) Nature produces a definite sol component in any single specimen of natural rubber. (2) The sol component can be separated and purified by refractionation methods. (3) Purified sol rubber retains the it can be vulcanized to yield a product of physical properties of natural rubber; it can be vulcanized to yield a product of superior quality. (4) No experimental evidence exists to justify the opinion that rubber is a two-phase system. (5) Sol rubber and gel rubber are mutually soluble.
The Limiting Degradation of Rubber Solutions
Authors: Bary Paul , Fleurent Émile
Published: February 2011

In our preceding papers [cf. Compt. rend., 192, 946 (1931); 193, 852 (1931); 195, 655 (1932)] we have pointed out that the degradation of solutions of rubber in xylene at concentrations of one to five per cent and at temperatures of 44° and 92° C. in sealed tubes tends toward a limit which depends upon the concentration and upon the temperature. One of the series of experiments carried out to determine the conditions under which this degradation takes place was continued to the point where the viscosity of the solutions reached a constant value in every case. With five per cent rubber solutions this result was obtained after a time which was practically of the order of 10,000 hours of heating, while the more dilute were the solutions and the higher was the temperature, the shorter was this time. At this limit, the viscosity of the solution reaches a final constant value for the particular temperature. It is therefore of interest to compare the law of viscosity as a function of the concentration of solutions, represented in its final form by the general formula of Arrhenius, for the viscosity as a function of the concentration of lyophylic colloidal solutions:
Rubber Antioxygens. III. The Behavior of Natural and Artificial Protective Agents toward Sunlight and Ultra-violet Light (Preliminary Communication)
Authors: Kirchhof F.
Published: February 2011

It has been shown that the reducing power of the water-soluble substances extracted from raw rubber is destroyed by the action of sunlight and ultra-violet light on raw rubber. This effect of light may be seen in a very striking way by treatment with an ammoniacal solution of silver nitrate of partially irradiated rubber sheets, which in a certain sense represents a “development.” In contrast to raw rubber, the most highly purified Tjipetir-gutta-percha, which contains no protective substances sensitive to light, forms peroxides with natural or artificial irradiation. These peroxides in turn reduce ammoniacal silver nitrate solution, so that irradiated samples of crepe rubber and Tjipetir-gutta-percha when developed with the reagent mentioned give pictures which behave negatively and positively. Finally the behavior toward ultra-violet light of a few artificial protective agents was investigated. Further experiments will be devoted to the problem of vulcanized rubber under the same conditions.
Studies on the Nature of the Action of Organic Accelerators for Rubber Vulcanization. II. Special Properties of Organic Accelerators. Part 1
Authors: Shimada Keiichi
Published: February 2011

In previous communications the author has studied the effect of various organic accelerators on rubber sols, and has been led to the conclusion that organic accelerators can be classified into three main groups according to the characteristic manner in which they affect the viscosity of rubber solutions. The object of the present paper is to invite more quantitative considerations and discussion based on the experimental results obtained in the previous papers. In the first part of this work the author has taken into consideration the special properties of the third group accelerators, which seem to be most important and significant from both a physico-chemical and a technico-chemical point of view.
Studies on the Combined Action of Organic Accelerators for Rubber Vulcanization
Authors: Minatoya Shukusaburo , Kojima Kitaro , Nagai Izumi
Published: February 2011

Keeping pace with recent developments in the rubber industry in general, various organic accelerators of good quality have been invented one after another, nearly one hundred different kinds of them being now put on the market. Though most of these accelerators, even when used singly, are satisfactory for regulating the time of vulcanization and improving the quality of vulcanizates, the combined use of two accelerators has come to be the subject of rubber chemists interested in this field, in order to obtain more. efficient results on vulcanization. Thiollet and Martin (Caout., 26, 14,494 (1929)) and W. Norris (Ind. Rubber World,82, No. 2, 535 (1930)) have already published the results of experiments on the combined effect of organic accelerators, and state that in vulcanization they behave in a different manner from any single accelerators used separately. In these investigations, however, rather impure chemicals on the market were incorporated in rubber stocks, and only in arbitrary proportions, regardless of the proportions corresponding to their chemical constitutions.
The Volumetric Determination of Free Sulfur
Authors: Castiglioni A.
Published: February 2011

In order to determine free sulfur in substances like rubber and antimony sulfide, extraction is carried out with a solvent, preferably acetone. After separation from the solvent, the extracted sulfur is converted into the sulfate and weighed as barium sulfate. With the object of making this determination, easier and simpler, it occurred to the author to determine the sulfur in the acetone extract volumetrically, instead of gravimetrically, by utilizing the observed fact that potassium thiocyanate is formed when the acetone extract is boiled with potassium cyanide. Experimental investigation of this subject showed that in the presence of an excess of potassium cyanide, conversion of the sulfur into potassium thiocyanate is quantitative, so that after evaporation of the solvent a mixture of potassium cyanide and potassium thiocyanate remains behind. To determine the potassium thiocyanate in the aqueous solution of these two salts, the method of Schulek (cf. Z. anal. Chem., 65, 433 (1924–25)) was used, which is based on the decomposition of potassium cyanide by formaldehyde. Instead, however, of adding an excess of titrated silver nitrate solution, as recommended by Schulek, and then determining the excess silver by the Volhard method, the titration was carried out directly with the silver nitrate solution, using iron nitrate as indicator, until the blood-red color of ferric thiocyanate had disappeared. In the following table are given the results of determinations by this procedure.
The Balance-Plastometer: a Simple Instrument for Measuring Plasticity and Recovery of Soft Materials
Authors: Hoekstra J.
Published: February 2011

The theory of parallel-plate plastometry has recently been studied extensively by Scott and by Peek. Though the time-flow relations for substances following Bingham's or de Waele's laws are more or less mathematically solved by these authors, this is not the case for substances like rubber, which have no true yield value. Peek says that, in the case of rubber, there occurs an “overlapping of the elastic and the plastic stage,” so that the results are ambiguous. This remark seems to us very much to the point. By reason of this “overlapping” the question of the “recovery” of masticated rubber and related substances is as yet rather unsolved. Karrer's method of expressing plasticity (“softness”) and recovery in one figure is not to be regarded as a solution of the problem. Moreover, his instrument for measuring the recovery has the great disadvantage of a fixed time and rate of compression. There is no possibility of varying the time and the percentage of compression to any great extent; therefore, with his instrument it is not possible to study the way in which the “yield value” or the degree of plasticity varies with the time and the percentage of compression.
Low Sulfur Compounding
Authors: Somerville A. A. , Russell W. F.
Published: February 2011

Since the beginning of the rubber industry, sulfur dosages used for soft rubber have declined from 20 to 2 or 3 per cent customary today. The decline is still under way, and present sulfur ratios are high in comparison with what is actually required to produce satisfactory commercial vulcanization—fractions of 1 per cent. Vulcanization with extremely low sulfur ratios, the use of selenium and tellurium as auxiliary vulcanizing materials, and the proper type of acceleration required to “cure in” all the sulfur and produce satisfactory commercial results, are discussed. Comparative data, covering many physical attributes, are shown for pure gum and gas black stocks compounded with 3 per cent sulfur on the one hand, and 0.3 and 1 per cent (gas black stock) on the other. Advantages of very low sulfur compounds are less tendency to scorch, better physical properties, better aging, higher resilience and lower power losses, less discoloration, greater resistance to hot solvents, greater abrasion resistance, and less flex-cracking on aging; disadvantages are higher set at low temperatures and reduced capacity to adhere to metals. It seems probable that, in the future, compounding will be based largely on the use of very low sulfur ratios.