bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vulcanization of Rubber in the Presence of meta-Dinitrobenzene
Authors: Wright J. M. , Davies B. L. 
Published: February 2011

Abstract
Since Ostromislensky (J. Russ. Phys. Chem. Soc., 49, 1456 (1916)) claimed that vulcanization of rubber in the presence of m-dinitrobenzene entailed the addition of oxygen to the rubber molecule, it has been suggested that this form of vulcanization may be the oxygen analog of ordinary sulfur vulcanization. Blake (Ind. Eng. Chem., 22, 740 (1930)), however, extracted vulcanizates with acetone and determined the nitrogen content. If it were assumed that the unextractable nitrogen was combined with the rubber, the figures indicated that the chemical reaction was monomolecular, and in explanation it was suggested that consecutive reactions occurred, one of which was slow. The vulcanizate was concluded to be an additive compound of the vulcanizing agent with the rubber. Objects and Technic.—The objects of the present work were to answer two questions: (1) what are the reactants, and (2) in what manner do they react? It was hoped with the simplest binary mixtures to find what were the essential ingredients, and to proceed to increasingly complex mixtures to discover the roles of the various accessory substances. By vulcanization in solution it was found that the examination of the final reaction mixture was facilitated. The mixes were therefore dispersed in technical xylene, of boiling point 140° C., and vulcanized by boiling. At a particular stage, the rubber became insoluble, and the time required to arrive at this stage was a characteristic of the mix and was taken to be proportional to the rate of reaction.
Composition and Structure of Hevea Latex
Authors: Kemp A. R. 
Published: February 2011

Abstract
Many properties of rubber are intimately related to the composition and structure of latex from which it is made. Some of these relations, however, remain obscure since our knowledge of latex structure and of the inner properties of rubber is lacking. The purpose of this paper is to help clear up some of the important questions relating to latex and rubber structure and to discuss their possible bearing on rubber properties. Composition of Ammonia-Preserved Latex This work and that of F. F. Lucas on ultraviolet microscopy of latex were carried out on commercial ammonia-preserved plantation latex taken from fresh shipments coming from two suppliers. The chemical analyses of these latices are given in Table I and are typical, although the composition of commercial liquid latex may vary somewhat, depending on many causes which will not be dealt with here.
Ultraviolet Microscopy of Hevea Rubber Latex
Authors: Lucas Francis F. 
Published: February 2011

Abstract
This paper is a report of studies made on two bulk samples of commercial rubber latex by means of the ultraviolet microscope. This apparatus does not appear to have been used to an appreciable extent for the study of the rubber latex particle. Green (1) applied it to vulcanized rubber latex and apparently made some observations on unvulcanized latex. The author is indebted to A. R. Kemp of these laboratories for suggesting the microscopical studies here reported. In his paper Kemp gives chemical analyses of the two latices used in this investigation, and their composition and structure are discussed.
Sorption of Water by Rubber
Authors: Taylor R. L. , Kemp A. R. 
Published: February 2011

Abstract
THE presence of water is one of the principal causes of electrical instability in dielectric materials, often resulting in large variations in direct current resistance, dielectric constant, and power factor. A knowledge of the laws governing the sorption of water is therefore of considerable interest to the electrical and communications industries. The various investigators in the field of sorption of water by rubber have not reported their findings in a manner which will permit of consistent interpretation and correlation for engineering uses. Insufficient attention has been given to the effect of such factors as shape of test specimen, temperature control, variations in vapor pressure, chemical changes in the test specimen, etc. Consequently no sorption coefficient suitable for application to practical problems and no measure of the rate of sorption which will permit an adequate comparison of one material with another is now available. The purpose of this article is to describe the relation between rate of sorption and some of these variables, such as thickness of test specimen, temperature, and vapor pressure, and to show how sorption tests can be applied to certain practical problems. It is not the purpose to present a survey of the literature. The word “sorption” is used in conformity with current phraseology to mean the combined effect of adsorption and absorption.
Azo Dyes Derived from Rubber
Authors: Low Rodolfo 
Published: February 2011

Abstract
At one time the greater part of the rubber used in industry was in the form of wild rubber, and although it is true that even under these circumstances rubber possessed the valuable properties which make it one of the most useful of materials for the widest variety of applications and in general indispensable, it nevertheless varied greatly. This latter fault not only made it difficult to manufacture rubber goods satisfactorily but limited the field of applications of rubber. Then again, sufficiently large quantities of the most useful raw material could not be obtained regularly. In contrast to this, the progress which has been made up to the present time in the cultivation of rubber has put industry in possession of a uniform product which is available in quantities sufficient to fulfil all needs. This has made it possible not only to manufacture rubber products in a more satisfactory way, but also to increase to an unforeseen extent the number of applications of rubber. Moreover, when it is realized that crude rubber is a relatively cheap material, it will be evident why chemists are busy utilizing it for the production of derivatives which, because of new and valuable properties, will necessarily find wide fields of application. This is only one instance of the constant attention which the chemist gives to the possibility of transforming materials which nature has bestowed upon us into other materials of still greater benefit to humanity.
The Deposition of Rubber on to Textile Fibers
Authors: Blow C. M. 
Published: February 2011

Abstract
(a) The preliminary results obtained in an investigation of the deposition of rubber from latex on to textile fibers are recorded. Methods of deposition have been considered in order to avoid the rubbery handle associated with evaporated films of latex. (b) The cationic soap compounds recently produced commercially enable satisfactory deposition to be brought about. (c) Data are given of the adsorption by textile fibers of these compounds. (d) The effect of cationic soap compounds on rubber latex and the production of a latex of reversed charge are described. (e) The two alternative processes for deposition of rubber are discussed: the first employs natural latex in conjunction with textile fibers pretreated with cationic soap; the second employs latex treated with cationic soap in conjunction with untreated fibers. (f) A short discussion of the theoretical basis for the results is given.
Compression Tests of Vulcanized Rubber
Authors: Ariano R. 
Published: February 2011

Abstract
Compression tests are used to a small extent in ordinary control testing of rubber mixtures prepared in the laboratory, but it is not possible with such tests to decide from an examination of various finished products which of the products will give satisfactory service under compression. Results obtained by this test have been in many cases contradictory, and it is safe to say that their conversion into analytical expressions has led to as many conclusions as there are authors who have worked on the subject. It appears then that the number of variables involved in a compression test is so great, and at the same time these variables are so little understood, that the test is meaningless at present. Naturally then one is induced to study the subject in detail, with the hope of being able to decide on the ultimate possibilities of the test and on the most favorable conditions under which it will give clearly defined results. With this in mind, it seemed opportune to determine the distribution of the deformations which take place in cubical test-specimens when their surfaces are lubricated and when they are not, and when the specimens are solid and when they contain holes in various locations.
Some Applications of High-Frequency Electric Currents to the Latex Industry
Authors: Leduc Henri 
Published: February 2011

Abstract
The “radiocoagulation” of latex has been developed in the laboratories of L'Office National des Recherches et Inventions by Dufour and Leduc, who conceived the idea of applying the effect of electric fields of high frequency to rubber latex. When latex is exposed to the action of an electric field of high frequency, the entire body of liquid is heated uniformly, provided that the electric field itself is uniform. The causes of this heating effect are difficult to ascertain because various phenomena are involved simultaneously, e. g., a dielectric loss in the rubber and a loss by the Joule effect in the serum. Each of these effects is, according to conditions, the predominant one, e. g., by increasing the conductivity of the serum, electrolytes such as sodium sulfate or ammonium sulfate increase the Joule loss, U2/R, whereas an increase in the concentration of latex tends to increase the dielectric loss. Finally, since rubber particles are not electrically neutral, they are subject to alternating forces of the electric field, which is a specific effect of the high frequency, and these forces impart to the rubber particles movements throughout the liquid. Now latex can be rendered sensitive to mechanical forces, i. e., some mixtures can be coagulated by slight agitation. Accordingly it is conceivable that a high-frequency electric field, by setting the rubber particles in motion throughout the emulsion, is capable of coagulating a mass of latex exposed to the field.
Processing Characteristics of Rubber Compounds- - -. Effect of Pigment Particle Size and Surface
Authors: Nellen A. H. , Barnett C. E. 
Published: February 2011

Abstract
A STUDY of the processing properties imparted by any pigment to a rubber compound is important in determining the most effective and economical type of pigment for a particular purpose. For example, in a truck tire carcass compound where zinc oxide may be the main pigment, in order to obtain the maximum quality this zinc oxide should be of the type which will give a soft uncured stock and free-flowing qualities so that the cords in the carcass may be thoroughly impregnated during the calendering and curing processes. Also, in a tread compound where channel black is the main pigment, that type of black which will allow faster incorporation into the rubber, faster extrusion, and better flowing qualities will result in manufacturing economies. In the case of both the zinc oxides and the carbon blacks it is essential that these desirable processing characteristics be obtained without losses in other properties, such as rate of cure, tensile strength, and abrasion resistance.
Observations on the Viscosity of Rubber Solutions
Authors: Guth Eugene 
Published: February 2011

Abstract
A simple comparison is sufficient to show the great difference between a latex and a solution of rubber of the same concentration. The viscosity of rubber solutions is as a matter of fact very much greater. Furthermore, the viscosities of solutions of artificial rubber are still greater than those of solutions of crepe rubber. This general difference in viscosity may be ascribed to a difference in shape of latex particles and that of particles of natural and artificial rubber in solutions. Latex particles are spherical, whereas the particles in solutions of natural and of artificial rubber appear to be long filaments. Twenty years ago, Einstein in a fundamental work treated mathematically the problem of viscosity of suspensions of spherical particles. He found that the viscosity of a suspension of spherical particles in low concentration can be expressed by the following equation:
Preparation and Testing of Latex Compounds
Authors: MacKay J. W. 
Published: February 2011

Abstract
Films should be prepared in an atmosphere free from air currents at 60 to 75 per cent relative humidity and at a temperature of 21.2° to 29.2° C. (70° to 85° F.) during the first 8 hours of the drying period. These films should be suspended for complete drying for an additional 48 hours at 0 per cent humidity and 10° to 15.5° C. (50° to 60° F.) before curing. The water-cured films should be dried 3 hours in the open room followed by about 20 hours at 0 per cent humidity and 10° to 15.5° C. (50° to 60° F.) before the preparation of test pieces. The air cures are kept in a desiccator for about 24 hours at 0 per cent humidity and 10° to 15.5° C. (50° to 60° F.) before the preparation of test pieces. The die for preparing test pieces must have perfect cutting edges. Test pieces should be conditioned 48 hours at 0 per cent humidity and 21.1° C. (70° F.) before testing to obtain maximum tensile and modulus results. The effect of humidity on physical test will be greater on normal latex, Revertex, and stabilized latex because of their increased water-soluble constituents which increase water adsorption. Good averages are obtained from three of four test strips broken, but for accurate work the average of the best four of six test strips should be taken.
Surface Application of Age Resisters to Cured Rubber vs. Mill Incorporation Prior to Cure
Authors: Semon W. L. , Sloan A. W. , Craig David 
Published: February 2011

Abstract
If the results of bomb aging, oven aging, and sunlight exposure are compared, one is led to the conclusion that the deterioration of rubber is a complex phenomenon. The relative effectiveness of the different deterioration inhibitors varies with the test applied. The rubber technologist is interested, not only in the protection afforded against heat deterioration, continued cure, oxidation of the rubber, deterioration caused by oxidized sulfur, or deterioration induced by sunlight; but also in properties such as the activation of accelerators giving rise to definite desirable types of vulcanizates, plasticizing or stiffening of the uncured stock, improved dispersion of the pigments, decreased scorching tendencies, elimination of surface tackiness caused by dry air cure, and prevention of flexure cracking in the cured product. Surface application may be effective with respect to all of the properties listed in the first group, but only mill incorporation can lend the advantages enumerated in both groups. Moreover, wear will remove a large part of the age resister applied to the surface which cannot have penetrated by diffusion to a concentration beyond its solubility, whereas abrasive action may expose new portions of age resister milled into the stock.
Method for Preparing Micro-Sections of Rubber
Authors: Steele Tracey F. 
Published: February 2011

Abstract
IN THIS laboratory it is frequently necessary to prepare micro-sections of a large variety of rubber compounds, cured and uncured, containing from 2 to 50 volumes of pigment. Smear mounts are quite satisfactory for the identification of pigments, but not for dispersion investigations. There have been some indications that the pressure required to make the rubber thin enough to transmit light causes changes in the dispersion. Furthermore, rather high temperatures are required to cause the highly pigmented stocks to flow under the cover slip. Green's sulfur chloride method (1) of destroying the elasticity is unsatisfactory with uncured stocks, causes certain undesirable changes in the appearance of some stocks, and requires modifications in procedure with different types of compounds. Freezing with liquid air has the inherent advantage that no permanent change is effected in the rubber and that all compounds, both raw and cured, can be treated essentially the same. Any of the usual mounting materials, however, such as paraffin wax, rosin combinations, etc., either crumble away, leaving little support for the rubber, or become so hard that the microtome knife is damaged.
Overflow during Vulcanization. Its Dependence upon Inactive and Active Fillers, and Errors in Previous Calculations of the Specific Gravity of Vulcanizates Resulting from It
Authors: Ditmar Rudolf , Preusse Carl Heinz 
Published: February 2011

Abstract
1. Raw rubber undergoes no change in volume during vulcanization. 2. Whenever it is vulcanized with sulfur there is an increase in volume. 3. Every inactive filler influences the overflow (increase in volume) in a characteristic way during vulcanization. 4. An increase in the proportion of a given inactive filler influences the overflow curve in a manner characteristic of the filler concerned. 5. Different inactive fillers influence the overflow in various ways. 6. Active fillers influence the overflow curve in a different manner from inactive fillers. 7. An increase in the proportion of a given active filler influences the overflow curve in a manner entirely characteristic of the filler concerned. 8. Different active fillers influence the overflow in quite different ways. 9. The specific gravity of a vulcanizate with sulfur is always less than the specific gravity of the corresponding unvulcanized mixture. 10. All calculations of specific gravity heretofore made in the rubber industry and theories related to them are incorrect because they are based on the false assumption that no increase in volume occurs during vulcanization. 11. Specific gravity determinations of mixtures must be based on overflow determinations.
The Dispersion of Gas Black and the Physical Properties of Rubber Mixtures
Authors: Grenquist E. A. 
Published: February 2011

Abstract
Many rubber technologists have already shown the importance of the dispersion of pigments in order to obtain the maxima physical properties of rubber mixtures. In a recent publication on the physical properties of gas black Carson and Sebrell state that they do not know of any article based on tests which deals with the relations between the dispersion of gas black and the properties of corresponding mixtures. Wiegand has already shown, in discussing mixtures highly loaded with gas black, that an incomplete dispersion of the pigments is no longer possible if the consistency of rubber falls below a definite value. He states that the lustre on the surface of a sample such as is used to determine tensile strength is a good method of estimating the degree of dispersion. Hauser upholds the idea that certain pigments attain a maximum dispersion during milling. In two preceding communications I studied the distribution of gas black in vulcanized and unvulcanized mixtures. I showed that changes in dispersion occur during milling as well as during vulcanization, and I discussed the theoretical possibility of obtaining the maximum dispersion and reënforcement. On the contrary, I am not concerned in these articles with the actual physical properties of the mixtures examined. In the present work, I wish to attempt to establish the relations between the dispersion of gas black and certain physical properties of rubber mixtures, whether vulcanized or not. The dispersion was determined by means of the microscope on freshly cut surfaces of mixtures vulcanized and unvulcanized, using a Leitz vertical illuminator and a Zeiss arc lamp as the source of light. Magnified about 300 times, the aggregates of gas black appear like a non-homogeneous black mass, while on the smoother and more homogeneous surface of the rubber the reflection is so increased that the field remains lighted.
Change of Electrical Properties of Rubber and Gutta-Percha during Storage under Water
Authors: Curtis Harvey L. , Scott Arnold H. 
Published: February 2011

Abstract
A number of samples of rubber and gutta-percha were stored under water for about seven years and electrical measurements made on them periodically to determine the effect of aging on the resistivity, dielectric constant, and power factor. The dielectric constant was measured under three different conditions, namely, 60 cycles alternating current, pulsating direct currentusing 0.6 second charge with 0.1 second discharge, and pulsating direct current using the same time of charge with 1 second discharge. In all cases the dielectric constants increased with time unless failure was approached. A sample was considered to have failed when measurement of its capacitance became impracticable. The changes of the resistivity and power factor varied from sample to sample. The approach of failure was first indicated by the resistivity. When a curve was plotted with time the sample had been under observation as abscissa and resistance of the samples as ordinates, the curves of the sample which failed showed a break or marked change in direction several months before actual failure occurred. With similar curves for power factor and direct-current dielectric constant, breaks occurred at a later time. The time interval between the break in the resistivity curve and the breaks in the other curves was a function of the rate of decrease of the resistivity. These facts indicate that the failure of a sample is the result of its decrease in resistivity. This decrease in resistivity has been ascribed to the formation of fine holes through the material. This explanation was confirmed by the microscopic examination of microtome sections of the samples which failed. These sections showed fern-like figures projecting into the rubber. All of the samples that failed were in the form of tubes, with water electrodes both inside and outside the tubes. Some copper salts were inadvertently allowed to form inside the tubes. The catalytic action of these copper salts accelerated the aging, and probably changed its character.
A Study of Gutta-Percha and Balata by Means of X-Ray Spectra
Authors: Hopff H. , Susich G. V. 
Published: February 2011

Abstract
The x-ray study of gutta-percha and balata has already been undertaken by G. L. Clark, E. A. Hauser, and his collaborators as well as by E. Ott. Their results are contradictory, however, in many respects. For example, Clark gives different values for the lattice of gutta-percha and for the lattice of balata, while Hauser has observed a difference for the angle of deviation only with stretched samples, and consequently proves that the position of the point interferences of the fiber diagrams is identical for both substances. Moreover Ott's values for gutta-percha vary greatly from those given by Clark. The roentgenographic observations referred to agree only in two respects: 1. Gutta-percha and balata are already crystalline in the unstretched state. 2. The lattice of gutta-percha and of balata is different from that of rubber. We have studied gutta-percha and balata by means of x-rays with the idea of clearing up the disagreements in previous publications and of determining whether or not there is any difference between gutta-percha and balata.