bluuebunny/crossref_metadata_2025_split huggingface dataset:
Notes on Defects in Smoked Sheet and Crepe Rubber
Authors: Fullerton R. G. 
Published: February 2011

Abstract
In the following paragraphs a general account is given of the characteristics and the nature of commonly occurring defects in smoked sheet and crepe rubber, and of the principle underlying methods for their prevention as recommended for estate practice. Many of the defects referred to have no harmful effect on the quality of the rubber after vulcanization, and in the majority of cases the only reasonable excuse for their classification as defects is the unsightly appearance which they impart to the raw product. Since, however, standards of quality at present imposed by the market are based largely on appearance alone, methods have to be devised to prevent the occurrence of these defects.
Thermodynamics of Stressed Vulcanized Rubber
Authors: Gerke Roscoe H. 
Published: February 2011

Abstract
The first and second laws of thermodynamics are applied to the stretching of vulcanized gum rubber stocks. Equilibrium stress-strain curves without appreciable hysteresis are described. The modulus of elasticity of vulcanized rubber for higher elongations obtained from the equilibrium stress-strain curve is capable of giving agreement with predictions of the second law of thermodynamics and the Joule heat effect. The modulus of elasticity from the equilibrium stress-strain curve is practically independent of the time of cure for a range of cures for elongations less than 600 per cent. The customary stress-strain curves show the rubber to be stiffer with increased cure. These facts are additional evidence that the important effect caused by vulcanization is a greater resistance to plastic flow or permanent set.
The Tensile Strength of Java Plantation Rubber
Authors: de Vries O. , Riebl R. 
Published: February 2011

Abstract
In 1927 rumors were heard from different sides regarding a supposed decrease in tensile strength of plantation rubber. These took such a form that The India Rubber Journal took the matter in hand and published a review of data, furnished by different manufacturers and experts. We gave a short review of figures for Java plantation rubber for the years 1923-1926, from which no deterioration in tensile strength was to be seen; on the contrary, the figures showed a slight increase and the conclusion was that, at least for Java plantation rubber, there was no question of deterioration, as was to be expected for anybody conversant with methods of preparation on estates, which are more and more standardized and improved upon. We are now able to supplement these figures with the averages obtained in routine testing in our station during the years 1927-1929. The figures are:
The Coagulation of Hevea Latex
Authors: Beumée-Nieuwland N. 
Published: February 2011

Abstract
In checking up as to which substances are present in latex, we find the following: protein, which can act as a protective colloid, lipoids (sterols, lecithin which can protect the sterol, esters of sterols), and further the contents of the globules, which is probably viscous. In view of the above considerations it is my opinion that one can picture latex as follows: The rubber globules are suspended in a protein emulsion, and have a lipoid wall and a viscous content. In the case of ordinary coagulation, where the pH becomes 4.8, one might therefore form the idea that only the protein flocculated and formed a gel in which the globules stay put. Investigations by Rona and Deutsch have shown that the iso-electric point of lecithin is very much influenced by the presence of protein, and it is therefore probable that the lipoid substances will be flocculated already at that lower pH. When both protein and lecithin, the two hydrophilic colloids, are flocculated, there still remains the hydrophobic colloid sterol, which can easily be flocculated by the salts present. Then the contents of the globules are no longer protected, but stay included between the gels. The latter flocculation is irreversible and, therefore, once coagulation has taken place, inversion is impossible.
Studies of Conditions Affecting the Vulcanization of Rubber. IV. Heat Reaction during Vulcanization
Authors: Toyabe Yutaka 
Published: February 2011

Abstract
The heat reaction during vulcanization was traced by means of a differential thermocouple, of which one contact point was placed in a sealed glass tube enclosed in the sample and the other in the heating medium of a small electric furnace, e. g., asbestos yarn windings. Specially prepared rubber precipitated from latex by acetone was milled with varying quantities of sulfur and was vulcanized at 155° C. The heat change was observed during the vulcanization. The curves are shown in Fig. 1. Although the absolute or relative amount of heat evolved seems to be shown by the ordinate of the curves, it is not the case because of the uneven thermal resistivity of the samples. From these curves, therefore, it may only be seen that the profiles of them are similar to each other, showing maximum points at 60 to 70 minutes and decreasing asymptotically to a horizontal line, i. e., the temperature of the heating medium of the furnace. It is observed that the maximum points lie at about the same period, though the sulfur contents of the samples were varied. Similar results are shown by Perks (J. Soc. Chem. Ind., 1926, 142T). The present author analyzed the vulcanizates corresponding to the maximum points of the curves, the results of which are shown in the following table.
Evolution of Hydrogen Sulfide from Vulcanized Rubber
Authors: Wolesensky Edward 
Published: February 2011

Abstract
The rubber-sulfur compound in vulcanized rubber splits off hydrogen sulfide at all times and at all temperatures between 25° C. and the temperature of complete thermal decomposition. The rate of evolution of the gas depends upon the temperature, time, the proportion of combined sulfur, and possibly other factors. The reaction affords a new explanation of the formation of hydrogen sulfide during vulcanization, and possibly also, in part at least, of the excess of combined sulfur over that required by the formula C5H8S. It may also be another factor in aging, though, perhaps, only a minor one, and presents a new problem in the regeneration of rubber.
Recovering Lead in Rubber Factory
Authors: Haushalter F. L. 
Published: February 2011

Abstract
When we say that lead melts at 621 ° F. and has a tensile strength of 1900 lb. per sq. in., we have in mind pure lead that has not been remelted many times in crucibles that are not always clean. This metal, too, as ordinarily used in pipes and conduits has been drawn; stresses have been set up in the lead by this process, and their magnitude depends upon several factors, such as temperature of extrusion, extent of oxidation, rate of cooling, and impurities accumulated in the remelting. Where lead is melted and extruded onto wire and hose the tensi1e strength of such lead, when removed from the wire or hose, has increased to about 2400 lb. per sq. in. The percentage elongation, however, has decreased from about 50 to about 25. Industries where lead is used again and again by remelting, as in the rubber industry, where hose is vulcanized in a lead casing, the casing removed after vulcanization of the hose and remelted, the problem of controlling the physical properties of the lead becomes a serious one. After pure lead has been extruded onto the hose and the tensile strength thereby stepped up to about 2400 lb. per sq. in., the tensile strength then falls appreciably below the original value of 1900 lb. per sq. in. as soon as the vulcanization process begins, with the temperature of vulcanization at 280° F. When the samples of lead as stripped from the hose after vulcanization were tested for tensile strength at various temperatures, the curve approximated a straight line. A stress-strain curve on the lead at a temperature of 280?? F. indicates that at a tensile stress of about 600 lb. per sq. in. the lead begins to yield, for the curve departs from the original slope.
Polymerization Reactions under high Pressure. I. Some Experiments with Isoprene and Butyraldehyde
Authors: Conant J. B. , Tongberg C. O. 
Published: February 2011

Abstract
1. The rate of polymerization of isoprene under high pressures has been studied. The reaction is subject to positive catalysis by peroxides and negative catalysis by hydroquinone. Although the reaction is of a high order, the rate is approximately in accord with a first order reaction presumably because of an autocatalytic effect. The temperature and pressure coefficients of the rate have been estimated. The solubility and elasticity of the product depend on the extent to which the isoprene has been polymerized; when the polymerization is practically complete at room temperature at 12,000 atm. the product is very insoluble 2. The action of high pressures on n-butyraldehyde produces a solid only slightly soluble in organic solvents. It reverts to n-butyraldehyde rapidly. It is suggested that this polymer is similar to the well-known polymers of formaldehyde but that the energy relationships are such that the polymer is stable only at high pressures.
Natural and Synthetic Rubber. IV. 4-Methyl-4-Octene by Isoprene Ethylation
Authors: Midgley Thomas , Henne Albert L. 
Published: February 2011

Abstract
Isoprene has been ethylated; 4-methyl-4-octene was formed exclusively. The structure of this nonene is in agreement with the usual behavior of a conjugated double bond system. This type of addition is further evidence in favor of the hypothesis which regards the polymerization of isoprene to synthetic rubber as the formation of long chains of isoprene units linked together- by ordinary valences in the 1,4-position.
Natural and Synthetic Rubber. V. Tetramethyloctadiene
Authors: Midgley Thomas , Henne Albert L. 
Published: February 2011

Abstract
Dimethylbutadiene treated with potassium and alcohol gives 2,3,6,7-tetramethyl-2,6-octadiene and methyl-rubber. The structure of the first hydrocarbon has been established, and is used as an evidence that the methyl-rubber formula must be a long, open chain. This is also regarded as an evidence in favor of the chain formula of natural rubber.
Isoprene and Rubber. XIII. The Constitution of Rubber
Authors: Staudinger H. , Asano M. , Bondy H. F. , Signer R. 
Published: February 2011

Abstract
It is of special interest in connection with the structure of rubber as well as that of all natural products of high molecular weight that two basically different viewpoints exist, and that both have been supported by experimental investigations. Both these concepts concerning the constitution of rubber are discussed in the following paper. I. The Constitution of Rubber According to Pummerer Pummerer defends the correctness of the basic concept of Harries “that a parent rubber hydrocarbon exists, which as a result of some condition tends to association and as a result gives the impression of a rubber of gigantic molecular weight. The question of whether this point of view is justified is of the greatest interest to colloid chemistry. The tendency to association may depend upon various factors, for example, upon the state of saturation, upon the size, or even upon the form of the molecules”. Pummerer expresses similar ideas, as does Bergmann about the constitution of polysaccharides and albumins. This concept is supported by Pummerer by important experiments.
Some Studies Relating to the Compression and Shear Resistance of Rubber
Authors: Ingmanson J. H. , Gray A. N. 
Published: February 2011

Abstract
1. A method for evaluating rubber covered wire by correlating compression, shear, and adhesion tests with bomb aging has been described. 2. It has been shown that the shear test described can be used for evaluating vulcanized rubber compositions with certain advantages over tests commonly in use. 3. Methods and some few data regarding the compression characteristics of several rubber stocks and other deformable materials have been given.
The Compressibility of Rubber
Authors: Adams L. H. , Gibson R. E. 
Published: February 2011

Abstract
Although many of the elastic properties of rubber have been investigated with very interesting results, no measurements have been made, so far as we know, of its cubic compressibility at high pressures. Those measurements which have been made at low pressures yield results varying from 93×10−6 obtained by Clapeyron to an estimate of the order of the compressibility of bronze (about 1×10−6) given by Amagat. As the compressibility of rubber enters as a minor correction into most compressibility measurements at high pressures, it is very desirable to have a reliable estimate of its value. In this communication we propose to give the results of experimental determinations of the compressibility at 25° of three samples of rubber which were furnished to us by H. L. Curtis and A. H. Scott of the U. S. Bureau of Standards. The samples are described as follows: Sample A.—Hard rubber from panel made by the Goodrich Company. It is a rubber-sulfur compound containing no inorganic fillers. The total sulfur amounts to 27.4 per cent, of which 0.21 per cent, is free sulfur. The density is 1.149 at 27° C. Sample B.—A rubber-sulfur compound containing 90 per cent. smoked rubber and 10 per cent. sulfur and vulcanized 105 minutes at 300° F. Density = 0.990 at 25°. Sample C consists of pale crepe rubber 90.75 per cent., zinc oxide 5 per cent., sulfur 4 per cent., tetramethylthiuram disulfide 0.25 per cent. It was vulcanized for 30 minutes at 260° F. Density = 0.990 at 27°.
Studies in the Oxidation of Rubber Mixings
Authors: Davey W. Cecil 
Published: February 2011

Abstract
In a former communication (Trans. Inst. Rubber Industry, 4, 493 (1929)) some results were presented of studies on the changes of rubber samples oxidized to an intense degree. For that investigation the oxidation temperature used was 70° C. (Geer Oven), while in the present paper results are given of experiments made at 100° C. and their relation to the results at the lower temperature are discussed. The experimental procedure was similar to that previously used, the preliminary stage being the sheeting out of small portions of the samples by passing them through the tightly closed cold rolls of a laboratory mill. The weighed samples were then suspended by strings in an ordinary steam oven fitted with an air inlet near the bottom and an outlet at the top. The progress of oxidation of each sample was noted from time to time by (a) determining the increase in weight, and (b) removing and estimating the amount of resinous matter present by extraction with acetone for 24 hours. In some instances the acetone extraction was preceded by an extraction with chloroform.
Alternating Behavior of Fatty Acids in Rubber Compounds
Authors: Garner T. L. 
Published: February 2011

Abstract
It has been shown (Bayer, Ber., 10, 1286 (1877); Garner and Randall, J. Chem. Soc., 125, 881 (1924)) that the alternations in the melting points and heats of crystallization of normal fatty acids were due to differences in the crystalline structure. Two distinct curves of behavior corresponding to the acids with odd and even numbers of carbon atoms have been shown for the heats of crystallization. McKee (Naturwissenschaften, 11, 938 (1923)) discussing the fats used in the diet of diabetics, states that in the case of glycerides of acids with an uneven number of carbon atoms these are tolerated and their use leads to gradual reduction in acidosis. Glycerides having an even number of carbon atoms break down during metabolism to form butyric, oxybutyric, and acetoacetic acids. Smith and Boone (Ind. Eng. Chem., 19, 398 (1927)) have experimented with the addition of purified fatty acids to standard mixings of different kinds of raw rubber. They employed molar proportions of the acid to conform with the recommendations of Kratz, Flower, and Coolidge (Ind. Eng. Chem., 12, 317 (1920)) that comparisons of organic accelerators should be made with molecularly equivalent amounts of the substances in question. They determined the tensile strength and elongation of the vulcanized products and found no relations between the elongation and the number of carbon atoms present in the acids, but in the case of the tensile strength an alternating effect was evident, the extent of the differences being affected by cure. The tests were carried out on two kinds of rubber, namely, blanket crepe and pale crepe, and the alternating effect of the acids on the tensile strength was more marked in the former case. As pointed out in the paper, the difference in behavior of the two kinds of rubber when treated with fatty acids was presumably due to the difference in the kind and proportions of acids which they originally contained. In fact, in the case of pale crepe the fatty acids already present in the raw rubber masked the alternating behavior to a marked extent, and the curve obtained was in most respects quite different from that obtained with blanket crepe.
Influence of Light on the Color of White Rubber
Authors: Naunton W. J. S. 
Published: February 2011

Abstract
Defries and the writer published a note on the effect of sunlight on the color of cured and uncured mixings (Trans. Inst. Rubber Industry, 4, 248 (1928)) in which they ascribed the darkening produced by preliminary exposure to light as being due to a surface over-cure. Some time later Rimpel and Herrmann published a criticism (Gummi-Zeitung 43, 2270 (1929); see also (India Rubber J., 78, 943 (1929)) of this work, and contended that the discoloration of a rubber mix on curing after exposure to sunlight was a reduction phenomenon, and independent of state of cure. Rimpel and Herrmann made the following experiment: Four mixes were prepared, each consisting of rubber, lithopone, and zinc oxide. To the first of these sulfur only, to the second an accelerator, and to the third sulfur and accelerator were added; the fourth received no addition. After exposure to sunlight all the mixings were cured. It was found that the first and fourth mixings were unaffected, but the second and third mixings were discolored to the same extent. The inference was that the discoloration was due to the accelerator as such which behaved like the other reducing agents described in Rimpel and Herrmann's paper.
Studies in the Vulcanization of Rubber. II—Vulcanization of Rubber with Nitro Compounds
Authors: Blake John T. 
Published: February 2011

Abstract
The Kjeldahl method for nitrogen analysis can be adapted to the determination of combined nitrogen in rubber vulcanized with nitro compounds. The combination of nitro compounds with rubber has been followed in several cases. Strong evidence is given that the vulcanization is a chemical reaction. The density of rubber has been shown to change during vulcanization with dinitrobenzene. The change approximates the progress of the combination of the vulcanizing agent with rubber. The vulcanization of rubber with dinitrobenzene and trinitrobenzene is monomolecular. A theory of the mechanism of the vulcanization is advanced. The value of the stoichiometric method in estimating the molecular weight of rubber is discussed. Values of this constant are suggested by the data. Nitro compounds appear to be incapable of producing hard rubber. The amount of combined reagent is only a small fraction of that required for ebonite formation.
Solubility of Oxygen in Rubber and Its Effect on Rate of Oxidation
Authors: Williams Ira , Neal Arthur M. 
Published: February 2011

Abstract
It is apparent that an artificial aging test must consider the concentration of oxygen existing in the rubber. The concentration of oxygen in rubber suspended in air at 70° C. will be less than that required for normal oxidation at the maximum rate. This should limit the use of an air atmosphere to the highest quality of rubber in which the rate of oxidation is extremely small in comparison with the rate of diffusion of oxygen, and in this case tests should be confined to thin slabs. The solubility of oxygen in rubber suspended in oxygen at 70° C. and atmospheric pressure appears to be slightly greater than that required for uniform oxidation. Under these conditions thin slabs of good or medium-quality rubber should oxidize in a satisfactory manner. The fact that strips 4 mm. square of a rubber extremely sensitive to oxidation, when tested in an oxygen atmosphere at 26° C., produce deviation from a straight line would make doubtful the accuracy of tests conducted on easily oxidized rubber under these conditions. This type of rubber would require 2 or 3 atmospheres pressure in order to maintain the required oxygen concentration. The type of deterioration appearing at higher temperatures should have little influence unless high oxygen pressure is used. The use of both high temperature and high pressure may emphasize types of oxidation which are suppressed at ordinary temperature. Since little is known about this type of oxidation, it is believed that the simultaneous use of high temperature and high pressure should be avoided.
Structural Changes during the Processing of Rubber
Authors: Grenquist Ernst A. 
Published: February 2011

Abstract
The effect of mastication, heating in air, oxygen, steam, and carbon dioxide gas, and the influence of light upon the plasticity of crude rubber have been investigated. Cold milling causes a permanent change in the consistency of crude rubber, whereas heating in air or steam produces a temporary effect. In absence of air the rubber exhibits a maximum amount of disaggregation at each given temperature. At low temperatures the increase in plasticity proceeds at practically the same rate whether the rubber is heated in oxygen or in carbon dioxide. Ultra-violet light affects concurrently both the plastic and elastic properties of the rubber. The correlation between elasticity and double refraction of crude rubber has been shown. The anisotropic properties of rubber parallel the recovery values. In this investigation no agency has been found which causes such far-reaching and profound destruction of the elastic properties of the rubber as prolonged physical mastication. The interrelation between plasticity and structure of crude rubber has been studied and the fundamental difference between actual mastication and heat breakdown has been emphasized. Prolonged milling, heating in air, or in oxygen destroy the protein framework of the rubber. Heating in steam or in an inert gas leaves it more or less intact.
Behavior of Various Clays with Crude and Reclaimed Rubber
Authors: Winkelmann H. A. , Croakman E. G. 
Published: February 2011

Abstract
1—The chemical analysis of clays gives but little information regarding their behavior in crude or reclaimed rubber. Acidity or alkalinity should be determined for effect on rate of cure. Color of the clay is no criterion of its purity. 2—Clays show wide variations in plasticity, retentivity, and softness in crude and reclaimed rubber. 3—Commercial clays vary widely in their effect on the physical properties of crude and reclaimed rubber. In general, the effect of the clays is the same in reclaimed as in crude rubber. There is not quite the percentage variation in tensile strength in reclaimed rubber that there is in crude rubber. The alkalinity of the reclaim may have decreased the variation. 4—Bomb aging is an important test for differentiating between various clays. 5—The uncured as well as cured properties of a compound should be noted in compounding and processing various samples. 6—Microscopic examination of clays makes it possible to predict their effect on the uncured and cured properties in both crude and reclaimed rubber.