bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies in the Oxidation of Rubber Mixings
Authors: Davey W. Cecil 
Published: February 2011

Abstract
The rubber airbags used for inflation purposes during the vulcanization of motor covers gradually change during use, and a hard, brittle material forms inside. The bags can, however, be kept in use long after the rubber or, at any rate, the inside rubber, is in an entirely perished condition. The ordinary physical testing methods used for following the changes in rubber are, therefore, not available under conditions where the deterioration is very intense; but the changes can be satisfactorily followed by chemical methods. In the present paper are given briefly some of the results obtained during extensive studies of rubber submitted to prolonged oxidation in a Geer oven at 70° C. Experimental.—The samples were vulcanized for varying periods, and after vulcanizing were sheeted out thin and placed in small beakers in the Geer oven. The progress of oxidation was noted from time to time by measuring the increase in weight and by removing and analyzing portions of the samples. In the early experiments rubber-sulfur mixings were used for simplicity, but later the work was extended to accelerated mixings. In order to obtain a theoretical insight into the changes taking place, the rubbers were in some cases extracted with acetone before oxidation (aging); also the aging of rubber previously extracted with first acetone and then chloroform was studied. In some series samples were submitted to repeated aging and extraction, that is, after the extraction following aging the samples were again returned to the oven. After a further period of aging they were again extracted, and so on repeatedly.
Colloid Chemical Changes in Rubber and Fatty Oils
Authors: Auer László 
Published: February 2011

Abstract
In attempting to solve many of the problems in connection with the chemistry of rubber and of the fatty oils, it is usually found necessary to employ the main principles of colloid chemistry. It is, however, impossible definitely to classify rubber, as either lyophobic or lyophilic in nature. Raw rubber, such as pale crepe or smoked sheet, is in the presence of organic solvents of lyophilic nature, whereas it is entirely lyophobic when dispersed in water. Rubber latex shows an intermediate behavior between lyophobic and lyophilic systems. After neutralization of the electrical charge of the particles, i. e., at the so-called isoelectric point and slightly beyond it, the rubber particles do not flocculate. From this behavior it may be imagined that latex is a lyophilic system, but it is found that a comparatively small excess of electrolyte causes complete flocculation of the rubber, i. e., the salting-out of the rubber particles. Freundlich and Hauser (Kolloid Z., 1925, Erg. Bd. 36) have shown that the rubber particles in latex are made up of a liquid interior and a semi-solid external layer. The protein and resin content of the latex are supposed to be present in this external layer of the particles. Von Weimam (Bull. Chem. Soc. Japan, 3, 157 (1928)) has found that if latex is treated with solvents or solutions which are dispergators (dispersing agents) of protein compounds, and which thus cause a dispersion of the proteins from the external layer of the particles, the emulsion of the rubber hydrocarbon, normally lyophobic in character, will immediately assume a lyophilic nature and the whole system will gelatinize to a solid mass. It seems to be probable that in latex the rubber hydrocarbon is in a lyophilic state and that the partly lyophobic nature of latex is due to the lyophobic character of the protecting protein layer. Immediately this is dispersed, the lyophilic nature of the rubber hydrocarbon becomes evident. Concentrated lithium iodide solution acts as a suitable protein dispergator. As proteins have partly lyophobic and partly lyophilic nature, it is possible that the protein itself forms a gel skeleton containing the rubber hydrocarbon particles dispersed in it. In this case the rubber hydrocarbon may be of a lyophobic nature. Against this hypothesis is the fact that the gelatinization occurs in the presence of protein dispergators and not in the presence of protein coagulators.
The Swelling of Rubber
Authors: Stamberger P. , Blow C. M. 
Published: February 2011

Abstract
Some recent experiments on the diminution of the vapor pressure of solvents in rubber jellies, as well as measurements of swelling pressure, allow us to draw some conclusions as to the nature of the swelling phenomenon. It has been found that, at the same concentration of rubber, the vapor pressure of rubber jellies from rubber of different origin was the same, and the previous mechanical working (mastication) of rubber had also no effect on this value (cf. Stamberger, Rec. trav. chim., 47, 316 (1928)). After the mechanical working, however, it swells in an unlimited manner, and gives as a resulting product up to a concentration of 30 per cent a more or less viscous liquid. This behavior shows that the solvent is not bound by surface adsorption and that there is a great resemblance to the process of molecular disperse solution. The three solvents used for these determinations were carbon disulfide, chloroform, and benzene. The same relative vapor pressure diminution was found when the concentration has been calculated as grams of rubber in 1 gram-molecule of solvent.
A New Plastometer
Authors: Karrer E. 
Published: February 2011

Abstract
AT THE Swampscott meeting of the American Chemical Society an analysis was given of the meaning of plasticity when this term names a property of solids that concerns the molding of plastics such as rubber. A function for plasticity was deduced with some suggestions on the adoption of a C. G. S. unit of plasticity. Also, a design of a plastometer, based upon this analysis, was outlined. It is the purpose of this paper to give a full description of such a plastometer. Original Plastometer A detailed drawing of the instrument as first conceived in February, 1927, is given in Figure 1. The rubber sample, 1, in the form of a cylinder 1 cm. long, 1 sq. cm. cross section, is held between two vertical round rods, A and B, which will be designated as upper and lower plungers. These plungers consist of contacting end caps, 15, 20, of steel mounted upon porcelain tubes, 19, which in turn are cemented into sockets 16, 21. The lower socket, 21, slides through a bushing 22. Its nether end is cut obliquely, and by means of a spring is pressed into contact with the surface of a cylindrical wedge, 23, movable in and out by means of a drum nut, 25, fitted to the threaded end, 24, of the wedge. The height of the sample may be read to 0.001 inch off the scale on the drum nut, 25. The upper socket, 16, slides in a tube, 17, and has a bearing shoulder for the spring, 9, called the force spring. The upper plunger, together with other parts bearing upon it from above, is carried by a light spring, 27.
Stearic and Oleic Acids as Rubber-Compounding Ingredients
Authors: Dinsmore R. P. 
Published: February 2011

Abstract
IT IS proposed in this brief discussion to touch upon the relative effects of stearic and oleic acids in a few typical rubber stocks; then to discuss certain anomalies as to the effect of stearic acid on chemical and physical cure; and, lastly, to consider some of the differences found by use of different accelerators. Inasmuch as oleic acid is the chief impurity in commercial stearic—running from 10 to 15 per cent—it seems desirable to know the behavior of oleic acid alone. Comparison of Stearic and Oleic Acids The following data show the comparative effects of double-pressed stearic and commercial oleic acids in typical rubber
Effect of Increased Quantities of Stearic Acid on Tread Abrasions
Authors: North C. Olin 
Published: February 2011

Abstract
The only conclusion justified, therefore, is that, in so far as abrasion index is concerned, we must fall back on road tests. There the values depend, not only upon the abrasion resistance of the tread, but also upon the design of the tire, its load, position on the car, etc. The Grasselli abrader is of value in laboratory work, but the results must always be carefully scrutinized and must be interpreted within the actual conditions of test.
Effect of Stearic Acid on Reclaimed Rubber
Authors: Winkelmann H. A. , Busenburg E. B. 
Published: February 2011

Abstract
1—Stearic acid does not compare with other softeners in plasticizing efficiency when used in contact with vulcanized rubber scrap during devulcanization. 2—Stearic acid when added as a softener to devulcanized scrap on the mill prior to refining imparts properties which are very desirable. (a) Makes the reclaim batch more plastic, (b) improves tubing and calendering properties, (c) reduces nerve without production of excess tack, (d) improves curing properties (higher tensile strength, higher modulus, and improved molding properties) of reclaimed rubber, (e) when pigments are added it gives better dispersion with improved physical properties. 3—Stearic acid when used in compounds containing reclaimed rubber improves the curing properties of these compounds.
Stearic Acid in Litharge-Cured Rubber Compounds
Authors: Sheppard J. R. 
Published: February 2011

Abstract
Although an organic acid is essential to vulcanization with litharge, smoked sheet usually has enough natural acid for full activation. For example, when 5 per cent stearic acid (or similar softeners) was added to a standard smoked sheet in a high zinc oxide stock the properties were lowered. On the other hand, a “low-grade” rubber, Lapori, was greatly improved in a high zinc oxide formula by stearic and by other acids. Acidic softeners in a high zinc oxide stock increased set, even when they promoted vulcanization. In a pure gum litharge formula with smoked sheet, 1 per cent stearic had but little effect, while in a high gas black formula, 4 per cent stearic raised the tensile (probably due to improved dispersion) but had no marked effect on rate of cure. When litharge was used as the activator for mercaptobenzothiazole, stearic acid had but little effect either in pure gum or high gas black stocks. On the contrary, when zinc oxide was used proper curing was highly dependent on stearic, especially with gas black. The litharge-mercaptobenzothiazole compounds with gas black in tread stock proportions, either with or without stearic, yielded a high tensile over a wide range of cures.
Dispersion of Pigments in Rubber—II
Authors: Grenquist Ernst A. 
Published: February 2011

Abstract
A theoretical conception of the reënforcement of rubber by pigments has been developed. New experimental evidence has been presented which leads to a better understanding of the final dispersion and reënforcement of a rubber compound. It is shown that pigment reënforcement is influenced by (a) rubber structure, (b) the state of aggregation of proteins and natural resins, (c) the isotropic properties of carbonblack particles, and (d) the presence of recrystallized rhombic sulfur at the beginning of vulcanization. A PREVIOUS paper (10)* described the distribution of particles in compounded rubber with special reference to agglomeration and flocculation. It was emphasized that a correct understanding of the final dispersion and reënforcement of a rubber compound could only be obtained with a more thorough knowledge of the structure and physical-chemical properties of rubber and pigments themselves and of the nature of the vulcanization process. New experimental results in regard to these particular points are presented in the following investigation.
On the Reduction of Rubber Stress-Strain Determinations
Authors: Wiegand W. B. , Braendle H. A. 
Published: February 2011

Abstract
In this paper the authors seek means of eliminating the personal equation in the selection of rubber stress-strain data. It became necessary to determine the most probable or true values for tensile strength, elongation, and intermediate values. The authors, therefore, tested a complete inner tube, securing ninety-five breaks, which were then reduced by statistical methods. Frequency distributions of rubber stress-strain data do not strictly obey the law of accidental error, being negatively skewed for breaking values, and positively skewed for intermediate tensiles. The true values, therefore, are not the arithmetic means but the modes, which are found to differ from the arithmetic means in every case to an extent greatly exceeding the probable error of such means. Using these true values, and dividing the ninety-five breaks into successive groups of five, the latter were weighted according to four empirical methods and the results compared with the modal values. The method of selecting three highest elongations out of five together with corresponding tensiles was found most closely to approach modal values. This method is therefore tentatively advanced as a starting point for the standardized selection of rubber breaks.
Importance of Temperature and Humidity Control in Rubber Testing. II—Resistance to Abrasion
Authors: Gibbons W. A. , Bierer J. M. , Bridgewater E. R. , Cranor D. F. , Park C. R. , Schade J. W. , Shepard N. A. , Somerville A. A. , Soule K. J. , Rupert F. E. 
Published: February 2011

Abstract
This study shows that in determining resistance to abrasion the temperature of the room or cabinet should be controlled within ± 1 ° C. in order to avoid significant errors in the results from this source. Below are shown the percentage differences per degree Centigrade obtained with each of the stocks. It must be remembered that this probably holds only over the range of temperatures studied and might change rapidly outside of this range. As the temperature changes from 15 ° C. to 35 ° C., the resistance to abrasion changes per degree Centigrade in the following manner: In the light of the present investigation there will be no great error in results caused by differences in relative humidity either with the raw or vulcanized stock. Where laboratories are equipped to condition raw and vulcanized stock for stress-strain tests, it appears that it would be advisable also to condition samples for determining resistance to abrasion. It would at least tend to produce more nearly uniform results by eliminating possible sources of small errors. As the relative humidity during exposure of raw stock increases from 10 per cent to 100 per cent, the resistance to abrasion per 1 per cent relative humidity changes roughly in the following manner: As these variations are small compared with the experimental error, it is evident that if the relative humidity does not vary over too wide a range its effect may be neglected. The temperature of storing the cured samples while maintaining a constant relative humidity has a negligible effect as in the case of relative humidity. As the temperature increases the resistance to abrasion per degree changes in the following manner:
The Aging of Vulcanized Rubber under Varying Elongation
Authors: Somerville A. A. , Ball J. M. , Cope W. H. 
Published: February 2011

Abstract
1—Deterioration in the oven is approximately 30 per cent greaterat 100 per cent elongation than at 0 per cent elongation. 2—Deterioration in the bomb is almost independent of elongation. 3—Deterioration in ozone is greatest at 5 and 10 per cent elongations. 4—Deterioration in sunlight with respect to stretch is analogous to deterioration in ozone. 5—Cracking of the test rings occurs in both ozone and sunlight when the rings are stretched, but not in the oven or bomb. This cracking is greatest at 5 and 10 per cent elongations. 6—A 40 per cent carbon-black stock shows marked deterioration and cracking in both ozone and sunlight at about 10 per cent elongation. 7—High sulfur causes greater deterioration in ozone and sunlight than low sulfur. 8—Undercures show greater deterioration than the optimum cure in ozone and sunlight. 9—Loading with a filler such as whiting does not change the shape of the ozone- and sunlight-aging curves, and does not materially affect the percentage deterioration. 10—Rubber bands show progres sively poorer aging in the bomb as the stretch increases from 0 to 700 per cent, while in ozone they give an aging curve having the characteristic dip at about 10 per cent elongation, showing the least deterioration at about 400 per cent elongation. 11—Tetramethylthiuram disulfide (3 per cent) as a vulcanizing agent causes rather low percentages of deterioration in ozone and sunlight, and gives fairly flat aging curves. 12—Mineral rubber (24 per cent) causes a smaller percentage deterioration than 4 per cent except at the critical elongation of about 10 per cent. 13—Paraffin (1 per cent) causes pretty bad deterioration in ozone but provides some protection in sunlight. 14—Added antioxidant does not change the shape of the ozone- or sunlight-aging curves but may lessen the amount of deterioration. 15—Two antioxidants may give comparable results in both oven and bomb, but quite different results in ozone and sunlight. 16—Synthetic rubber gives a characteristic ozone-aging curve.
Natural vs. Artificial Aging
Authors: Krall Stanley 
Published: February 2011

Abstract
A CONSIDERABLE number of types of artificial aging are being used today in an endeavor to determine the aging properties of rubber stocks in a short period of time without waiting for natural aging results. The data reported here were taken from some that are being obtained by Sub-Committee XV, Committee D-11 of the American Society for Testing Materials. Experimental Three types of pneumatic tire stocks were aged by two natural and two artificial methods: (1) Slabs were hung separately in the dark. (2) Slabs were hung separately exposed to the weather. (3) One-inch (2.5-cm.) wide strips were hung separately in the Geer (2) oven at 158° F. (70° C.). (4) One-inch (2.5-cm.) wide strips were hung separately in the Bierer (1) oxygen bomb at 158° F. (70° C.) and 300 pounds (21 kg. per sq. cm.) oxygen pressure. The stocks tested were a pure gum stock, a first grade, and a reclaim tread stock as follows:
Accelerated Aging vs. Shelf Aging
Authors: Follansbee Everett M. 
Published: February 2011

Abstract
SAMPLES of rubber-insulated wire were aged by exposing to the diffused light in the physical testing laboratory. The thickness of wall of rubber surrounding the tinned copper wire showed a variation from 0.030 to 0.065 inch (0.76 to 1.65 mm.). The thickness of wall of rubber surrounding the tinned copper wire showed a variation from 0.030 to 0.065 inch (0.76 to 1.65 mm.). The samples were tested for tensile strength and elongation during the aging interval and the results were then compared with accelerated life tests obtained on the same samples when new. Average results on 480 different compounds, ranging in quality from a low-grade compound to a compound containing 60 per cent by weight of crude rubber, show the following relationship between shelf aging and accelerated aging.
Correlation of Various Aging Tests with Natural Shelf Aging
Authors: Cadwell Sidney M. 
Published: February 2011

Abstract
In view of the many variables involved in accelerated and shelf aging, and of the fact that the correlation between the two is only qualitative, it is believed that there are two practical answers to the aging problem. One is incessant care. If the stock is properly balanced, if certain impurities are absent, and if the state of vulcanization is correct, good aging will be obtained. The other answer, which seems to be safer, is to use antioxidants. A certain antioxidant has always improved the aging of all sorts of stocks under all conditions; probably other antioxidants will do as well. Therefore, the use of antioxidants is the practical answer to the aging problem.
Influence of Pigments on Some Physical Properties of Unvulcanized Rubber
Authors: Depew Harlan A. 
Published: February 2011

Abstract
The solubility of pigmented rubber in benzene can be changed by altering the interfacial energy between the rubber and the pigment, and this can be accomplished either by changing the surface of the pigment or by changing the nature of the rubber—as, for example, by treating zinc oxide with sulfur trioxide gas and by adding organic acid to rubber. A plausible explanation has been offered as to why pigments cause rubber to become insoluble. In specific cases it has been possible to predict the solubility of unvulcanized rubber containing pigments. Data are presented showing the change in solubility of unvulcanized rubber during storage in contrast to the constancy in consistency, which gives evidence of a weak rubber structure that develops in storage. The influence of time and temperature of milling on consistency and solubility is shown.
On the Permeability of Rubber Mixings
Authors: Davey W. Cecil , Ohya T. 
Published: February 2011

Abstract
In order to obtain the longest life for motor cover inflating air-bags two features are necessary in the rubber: (a) that it is a mixing not readily oxidized, (b) that it has a low permeability. This latter point has been discussed by Daynes (Trans. Inst. Rubber Ind., 3, 438 (1928)), and it is probable that it is a very important factor as at the temperatures normally used in vulcanizing the rate of diffusion of gas through rubber is greatly increased. It is conceivable that a mix having a low permeability and poor aging would outlast one having high permeability and good aging, as in the former case the deterioration of the rubber would be kept close to the surface. As little information is available on the effect of different mixing ingredients on the rate at which a gas passes through the rubber, the experiments outlined below were made.
The Question of Vulcanization without Sulfur: Experiments on Hot Vulcanization and Vulcanization in Ultravoilet Light with the Aid of 1, 3, 5-Trinitrobenzene and Picric Acid
Authors: Kirchhof F. 
Published: February 2011

Abstract
THIS subject has been previously treated by L. Eck. The present article contains merely the results of a few experiments, which, as might be anticipated, seem suited to assist but little the progress of sulfur's new rivals. We recall that Ostromislensky is said to have succeeded in obtaining vulcanizates of technical value by means of nitro-compounds, especially 1, 3, 5-trinitrobenzene, in the absence of sulfur or any substance forming sulfur.
The Surface Energy between Rubber and Fillers
Authors: Hartner Fritz 
Published: February 2011

Abstract
The purpose of this research was to increase the reliability and accuracy of the calorimetric method elaborated by Bostroem, and to discover and overcome any difficulties or sources of error in order that the method might be applicable to the investigation of problems concerning the chemistry and technology of rubber. The following points were to be considered: 1. The dependence of the “reinforcing” action of a filler on its concentration, and the utilization of the surface energy between rubber and filler. 2. The evaluation of the surface tension in the system raw rubber/filler. 3. The aging phenomenon of rubber and the possibility of making it reversible 4. The comparison of various commercial gas blacks at a given concentration.
The Natural Coagulation of Hevea Latex
Authors: Corbet Alexander Steven 
Published: February 2011

Abstract
A bacteriological study has been made of Hevea latex and it has been found that one organism predominates. The characters and biochemical reactions of this organism have been studied in detail and, as it does not appear to have been denominated previously, the name Bacillus pandora is proposed for it. B. pandora is able to decompose latex substance with production of acid and hence bring about separation of the rubber particles. At a later stage it attacks the proteins with ammonia production and so is responsible for the acid serum and alkaline surface layer observed during the natural coagulation of latex. The reason for the employment of ammonia and sodium sulfite as latex preservatives is discussed.