bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frosting of Vulcanized Rubber
Authors: Tuley W. F. 
Published: February 2011

Abstract
Rubber products, like most commodities today, must meet the public demand for attractive appearance. Anything which damages the finish is a problem for the technical man. An appearance problem which seems to have become frequent in recent years is concerned with a dulling or surface dimming of various types of rubber goods after vulcanization. This effect has been aptly called “frosting,” and it sometimes resembles actual frost. Frosting may be easily confused with bloom. It usually appears within a few hours or days after vulcanization. It differs from bloom in that it is not caused by migration to the surface of a component of the rubber composition. Bloom can usually be removed by solution in weak acid or alkali or in an organic solvent. Frosting cannot be removed. The microscopic appearance is also quite different. Frosting may occur on rubber vulcanized in a press or in an open-air or steam cure, such as is used for footwear. It is most noticeable on the bright finish of air-cured rubber goods. Sometimes it appears almost immediately after removal from the vulcanizer as a bluish sheen, which may later become almost gray. Frosting has been observed on a great variety of rubber products, including footwear, raincoats, inner tubes, druggist's sundries and other molded articles. Unfortunately there is no known way in which frosting can be removed after it has once formed. It can be covered with lacquer or other finish but this is seldom satisfactory when applied after vulcanization. A bloom of sulfur and sometimes of other materials can be removed by additional heating at vulcanizing temperatures, but this is not effective with frosting. If the rubber is not frosted within a few weeks after vulcanization, it seems to develop a resistance to frosting and is unlikely to frost later. Frosting was determined to be due to the ozone in the air. So far as the writer knows, the cause was first determined by S. M. Boyd in 1931. He found that the effect could be reproduced by exposing vulcanized rubber without tension in warm, humid, ozonized air.
Tentative Procedures for Testing the Variability of Normal and Concentrated Latex. Crude Rubber Committee, Division of Rubber Chemistry, American Chemical Society
Authors: Gerke R. H. 
Published: February 2011

Abstract
The Committee desires to emphasize that these tentative procedures for testing variability are not to be considered as actual specifications for buying or selling latex, since tolerances or limits are not given. Rather, it is the desire of the Committee to give what are believed to be reliable methods for the determination of the various properties of latex which have been listed. However, it may be necessary to revise some of these procedures from time to time, since the use of latex is in its infancy and improved methods are being rapidly developed. In listing these procedures the Committee does not mean to suggest that it is always necessary to use all of them in testing a sample of latex. In other words, it is up to the users and suppliers to select such methods and tolerances as they see fit which will best suit their purposes. The Committee desires to express deep appreciation to those who have been instrumental in preparing the attached procedures:
Chemical Reactions during Vulcanization
Authors: Hauser E. A. , Brown J. R. 
Published: February 2011

Abstract
Direct addition or bridging of sulfur seems to occur at the double bonds of the rubber in sulfur vulcanization without accelerators (Figure 5, a and b). In accelerated stocks the fact that sulfur combines in excess of one atom of sulfur saturating one double bond of the rubber hydrocarbon suggests that sulfur may also combine in a dehydrogenation reaction (Figure 5, c), and that this type of sulfur linkage is most effective in producing high tensile strengths. The excess loss in unsaturation on overcure indicates that direct polymerization without sulfur (Figure 5, d), as well as reactions of oxygen at the double bonds, may occur after most of the sulfur has combined, but that these chemical changes are not definitely associated with changes in the vulcanized structure as measured by tensile strength. In the vulcanization of a simple rubber-sulfur compound, infrared absorption data indicate that oxygen is combining with the rubber during overcure to produce a degradation in the hydrocarbon structure which is accompanied by a decided loss in tensile strength.
Catalytic Dehydrogenation of Monoölefins to Diolefins. Source Materials for Synthetic Rubber and Resins
Authors: Grosse Aristid V. , Morrell Jacque C. , Mavity Julian M. 
Published: February 2011

Abstract
Aside from the scientific value of the method described here for the catalytic dehydrogenation of monoölefins to diolefins, the present contribution has an important industrial, commercial, and military value, viz., as an economic source of raw material for synthetic rubber. The production of butenes from butanes and pentenes from pentanes has already been described. The present paper, showing the production of butadiene from butenes and isoprene from pentenes, is the connecting link between the billions of cubic feet of butanes present in natural and cracked gases and of butenes present in the latter, and the billions of gallons of pentanes available in natural gasoline and crude oil on the one hand, and the production of synthetic rubber from these raw materials on the other. The basic raw materials for the production of synthetic rubber therefore now include our tremendous resources of hydrocarbon oils, hydrocarbon gases, and coal to produce synthetic hydrocarbons, if and when our petroleum resources become exhausted. The production of synthetic rubber from butadiene and isoprene is well known. Wallach exposed isoprene to light and produced synthetic rubber. Matthews and Harries independently used metallic sodium to polymerize isoprene to rubber. Similar work has also been done bv others.
Mixing and Moulding without Mastication
Authors: Cotton F. H. , Hodson W. F. 
Published: February 2011

Abstract
The preliminary experiments described indicate the remarkable potentialities of the injection method of moulding rubber articles, whether produced from mixes of powdered or masticated rubber. Employing rubber powder made by the Stam process, intimate mixing with vulcanizing ingredients and fillers is essential, and may conveniently be achieved with simple apparatus by ball milling the ingredients. The necessity for heavy rubber machinery of the orthodox type is eliminated. It is desirable to employ an accelerator of relatively low activity, or a delayed action ultra-accelerator. With very fast accelerators, vulcanization begins either during mixing of the powder or while being forced from the injection cylinder to the mould. Such premature vulcanization leads to serious distortion. It is believed that the stresses to which a compressed rubber powder compound is subjected during the process of injection moulding are sufficient to rupture the individual rubber particles, to ensure cohesion, and promote satisfactory dispersion of compounding ingredients. It is confidently asserted that results superior to those instanced herein could be achieved with an injection moulding device designed to facilitate uniform heating of both top and bottom of the mould cavity. It is also felt that a careful study of the effect of changing the injection pressure and the size of the injection orifice might yield valuable information. The success attending these early experiments warrants extending the investigation to new types of rubber powder (cf. Rubber Age, 19, 335 (1938)).
The Preservation of Latex by Sterilization in the Presence of a Buffer Solution
Authors: Davey W. S. , Beeley F. 
Published: February 2011

Abstract
A method of preserving latex has recently been suggested by Spence which consists of the sterilization of latex by autoclaving in the presence of a buffer reagent. In view of the improved properties claimed for the material, together with the lower cost of production, both of which are of interest to producers of latex, the method has been investigated. It is concluded that the process is not of value as a practical method for the commercial preservation of fresh Hevea latex.
Studies of Hard Rubber Reactions VIII. The Corrected Coefficient of Vulcanization, and Its Upper Limit in the Accelerated Raw Rubber Compound
Authors: Numaziri Seiiti 
Published: February 2011

Abstract
In a previous paper (J. Soc. Chem. Ind. Japan 40, 111B (1939)) it was shown that compounds containing up to 60 per cent of sulfur give coefficients of vulcanization higher than the theoretical maximum value of 47. Strictly speaking, however, the sulfur present in these cases can be divided into the following parts : sulfur soluble in acetone; (a) true elementary sulfur; (b) sulfur combined with organic matter; sulfur insoluble in acetone; (c) sulfur combined with rubber; (d) sulfur combined with resins and proteins; (e) metallic sulfide. In the present experiments, these five kinds of sulfur were separated as far as possible to determine the true or corrected coefficient of vulcanization, and its upper limit.
Test Formulas for Reclaimed Rubber
Authors: Palmer Henry F. , Crossley Robert H. 
Published: February 2011

Abstract
The maximum variation from test to test obtained when testing a sample of reclaimed rubber in compounded test formulas is approximately half that experienced when the reclaim-sulfur test is used. When tested with sulfur alone, reclaimed rubber may show a widely varying tensile strength and elongation from lot to lot, whereas much less variation in results is observed if the reclaimed rubber is tested in a compounded formula. For this reason, and also because the results obtained are more indicative of final performance, test formulas of a general nature are preferable to the reclaim-sulfur test. When test formulas are used in preference to the reclaim-sulfur mix, there is no increase in the work of testing. A combination of dibenzothiazyldimethylthiolurea and diphenylguanidine gives very satisfactory results for most types of reclaim.
Apparatus for Measuring Slow Rates of Consumption, or Evolution, of Gas in a Closed System
Authors: Barr Guy 
Published: February 2011

Abstract
In aging tests of rubber, the temperature and sometimes the oxygen pressure are raised much higher than in normal use; this has been necessary because the criteria of change usually chosen have been insensitive. The uptake of oxygen may be measured with considerable precision and, hence, the aging temperature may be reduced. An apparatus is described in which the absorption of oxygen by rubber is observable after an hour at 50° C; among the samples examined the hourly absorptions varied from 0.6 to 3.4 mg. per 100 grams of rubber. A manometer indicates differences in pressure between two similar bulbs placed side by side, one containing rubber and oxygen and the other containing air only. A formula is given to convert differences in the readings of the manometer to masses of oxygen absorbed.
Analytical Methods in Rubber Chemistry. (IV) The Determination of Peroxidic Oxygen
Authors: Bolland J. L. , Sundralingam A. , Sutton D. A. , Tristram G. R. 
Published: February 2011

Abstract
In the previous publication, of Farmer, Tristram and Bolland, it was stated that methods were required to estimate the various forms in which oxygen occurs united to the rubber molecule, and a method for the estimation of hydroxyl oxygen was discussed. The determination of peroxidic oxygen in oxidized rubber presents two distinct problems. It is necessary to employ a method which, first, is satisfactory in the presence of unsaturation and, secondly, ensures effective contact between the long rubber chains and the analytical reagent. These requirements are both satisfied by the modification described below of the colorimetric method of Young, Vogt and Nieuwland. Before describing the modified technique, some mention must be made of the earlier methods and of the errors which arise when they are applied to the determination of peroxidic oxygen in unsaturated compounds. All the earlier methods for the determination of peroxidic oxygen depend on the oxidation of potassium iodide and titration of the liberated iodine. This method is open to the objection that the liberated iodine immediately attacks the double bonds remaining in the oxidized material. This difficulty was recognized by Stephens, who, using a method in which the peroxidic oxygen was reduced with stannous chloride, succeeded in estimating about 80 per cent of the total peroxide present in cyclohexene peroxide. Yule and Wilson estimated the peroxide in cracked gasoline by shaking with an acid solution of ferrous thiocyanate and back-titrating the resulting ferric salt with titanous chloride. The results were later contested by Young, Vogt and Nieuwland, who described the colorimetric method which has been adopted, with some modification, in the present work.
Accelerators for Latex. Water-Soluble Vs. Water-Insoluble
Authors: Abernathy H. H. 
Published: February 2011

Abstract
The data presented in this paper support the following conclusions : Little, if any, accelerator is lost when rubber latex compounds containing water-soluble accelerators are applied to porous surfaces. The indirect method of analysis used is sensitive enough to detect any appreciable loss of accelerator, and would have detected any loss large enough to have practical importance. The fact that films from a rubber latex compound, made by casting on a porous plate, have lower moduli and tensile strengths and are less resistant to aging than films made by casting on a glass plate, is apparently due to the physical nature of the porous plate.
Heat Resistance of Neoprene-GN Vulcanizates
Authors: Forman D. B. 
Published: February 2011

Abstract
Control of heat deterioration is a continuous problem for the chemist. In the case of rubber and synthetic elastomers, the rubber chemist has charted the changes in the physical properties of vulcanized elastomers during heat aging. He has developed many methods for retarding the deterioration of rubber compounds by heat; but with the newer synthetic elastomers the development of methods of retarding deterioration by heat is now an active subject of investigation. The degree of deterioration depends on the methods of compounding and curing the different elastomers, as well as on the conditions of aging. In general, continuous exposure to high temperatures softens natural rubber but hardens synthetic elastomers. Inherently Neoprene has greater heat resistance than natural rubber. Many investigators have described the heat resistance of rubber vulcanizates, but only a few have reported on the heat resistance of Neoprene vulcanizates, and these reports have been primarily comparisons of given Neoprene vulcanizates with one or more rubber stocks. The compounding of Neoprene (Type GN) for heat resistance was discussed by Catton, Fraser, and Forman. The oxygen bomb aging of Neoprene (Types E and GN) was compared with that of various rubber compositions by Neal, Bimmerman, and Vincent.
Vulcanization or Other Heat Treatment by Electrical Conduction
Authors: Yerzley Felix L. 
Published: February 2011

Abstract
This communication relates to the heating of plastic materials of. a semiconducting nature by passing electricity through them. In particular, it relates to the vulcanization of rubber and rubberlike materials, including Neoprene, with heat generated by the conduction of an electric current and, similarly, it relates to the heat treatment of thermosetting plastics by conduction of an electric current. It is well known that all electrical conductors are heated to some extent by the passage of an electric current. This heating is a direct consequence of internal resistance. The effect so obtained is proportional to the electrical energy absorbed, and is expressed by the equation: power=I2R, in which I is the current in amperes between two points and R is the corresponding resistance in ohms. The unit of power is the watt. Others have used electrical means of heating unvulcanized rubber, but the disclosures differ fundamentally from this proposal. For example, Neerlye coils a steel ribbon and an uncured rubber belt in a spiral and heats the coil by passing electricity through the steel. Newton claims vulcanization by abeam of electrons from a cathode ray tube. The most significant disclosure is by Dufour. This claims the “process for the vulcanization of rubber characterized by the feature that the rubber to be heat-treated is arranged as a dielectric between the electrodes of an electric condenser to which there is applied a high frequency alternating current of a periodicity of several million cycles per second”. This patent is characterized by utilization of high-frequency fields of the order of several megacycles per second. Further, it is not required in induction curing with high-frequency current that the electrodes be in actual mechanical contact with the rubber. Induction curing is facilitated when the material to be heated has both a high power factor and a high dielectric constant, but high electrical conductivity of appreciable amount is not essential to the application of the method.
Hardness Testing of Vulcanized Rubber. II. Comparisons of Readings of Various Instruments
Authors: Daynes H. A. , Scott J. R. 
Published: February 2011

Abstract
Tests have been made on numerous rubbers with the R.A.B.R.M. hardness gauge, the Strachan piezomicrometer, and the Pusey and Jones plastometer (using in each case ¼-in. and ⅛-in. diameter balls) and with the Shore durometer and Schopper hardness tester, to determine the relationships between the readings given by these instruments. The results are tabulated and represented graphically as correlation curves. A conversion chart is given by which the reading obtained with any one instrument or size of ball can readily be converted into the corresponding reading for any of the other instruments or sizes of ball.
Wild Rubber of Tropical Africa
Authors: Martin Geo 
Published: February 2011

Abstract
By common usage the term rubber has come to denote the product of Hevea brasiliensis, which is outstandingly the most economical producer of rubber hydrocarbon known to mankind, and yields a product which, for general utility, has not yet been surpassed. There are, however, hundreds of other plants which yield rubber and before the advantages of Hevea became firmly established, many of them were the subject of preliminary investigation, but the information available, judged by present standards, is incomplete, out of date, and would not enable a modern manufacturer to convert wild rubber into articles of assured quality. This is not because wild rubber hydrocarbon is necessarily inferior or different from that of Hevea, but because of the well-known fact that the chemical behavior of rubber, including capacity for vulcanization and resistance to oxidation, is modified in considerable detail by small quantities of some nonrubber substances, many of which are natural components of plants. These components are not always the same for plants of the same species, and are known to be different in plants of different species. Rubber-bearing plants are found in most countries, but outside the tropics, few of them yield enough rubber to make their cultivation worth while, even in these difficult times. The most prolific source of wild rubber is tropical and subtropical Africa, where there are known to be hundreds of different species of plants which yield appreciable quantities of moderately pure rubber, in addition to many plants which yield resinous latices, some of which are known to contain rubber and others of which, although previously not known to contain rubber, are now found to contain amounts which under present conditions may be regarded as appreciable.
The Compounding of Hard GR-S
Authors: Morris Ross E. , Mitton Philip , Seegman Irvin P. , Werkenthin Theodore A. 
Published: February 2011

Abstract
A survey has been made of hard GR-S with regard to sulfur requirement and effects of various pigments, softeners, and accelerators on tensile strength, ultimate elongation, hardness, and stiffness. Of particular interest where the observations that hard GR-S had a higher tensile strength than hard Hevea rubber, and that hard GR-S did not undergo much loss in tensile strength when compounded with 60 volumes of channel black or semi-reinforcing black.
Rubber Resins: Some Properties and Possibilities of Use
Authors: Mason Charles F. 
Published: February 2011

Abstract
However, their present uses and possible future uses deserve consideration. Their tendency to thicken in certain solvents has been applied to use in imparting false body (thickening) to certain varnishes. In such cases it is likely that the rubber resin is modified to reduce tackiness before compounding it into quick-drying spirit varnishes. As plasticizers for brittle resins and asphalts they afford a very inexpensive raw material. But, again, experiments must be performed to see if the rubber resin is compatible with the natural or synthetic one, as there is little information as to whether plasticizers form solid solutions or only mechanical mixtures with the resins after heating and mixing. In one case a large shoe manufacturer purchased many tons of gutta-percha resin for impregnation of threads used in sewing on soles; the object was to prevent the entrance of moisture into the shoe and to supply a flexible adhesive. Electric friction tape, which must have an eversoft tacky surface, is coated with a compound of a bitumen, regenerated rubber, and a gutta resin, and is similar in composition to readily appliable insulation pastes, which are used on underground electric cables. The use in ever-soft adhesives and in flypaper are only two of the minor ones. The application of these resins to textiles in the form of emulsions shows large possibilities, as they can be emulsified with ammonium oleate or linoleate and, on drying, leave behind films of rubber resin and the fat acid of the emulsifier. A hardened balata resin has been used in linoleum cement. The soft resin or even the oily one can be hardened by heating for four hours at 80° C, after adding 1 per cent of manganese resinate or 0.5 per cent of calcium carbonate. Treatment of the same resin with sulfur chloride results in a viscous resin which, when warm, can be pulled out into ropes like taffy candy and, when cold, is still viscous. In closing, the writer wishes to state that, even if a reader may fail to find here the exact information he desires about a certain rubber resin, let it be hoped that what information he does find will save many hours of fruitless toil.
Thermal Expansion and Second-Order Transition Effects in High Polymers. I. Experimental Results
Authors: Boyer R. F. , Spencer R. S. 
Published: February 2011

Abstract
The results presented here on second-order transitions are in general accord with what has been known for other high polymeric systems. The value of the volume-temperature technique for investigating the nature of polymeric mixtures and the homogeneity of copolymers has been emphasized. In Part II a theoretical treatment of second-order transition effects, including the related brittle point determination, will be given. Finally, Part III will permit a more expanded treatment of the behavior of Saran and other crystalline polymers.
The Stress-Strain Relation of Natural and Synthetic Rubbers
Authors: Wildschut A. J. 
Published: February 2011

Abstract
It is shown that Hatschek's formula for the stress-elongation curve of rubber—better known as Ariano's formula—does not hold for normally vulcanized rubber. The observation has been made that the stress-elongation curves of natural and synthetic rubbers follow nonrectangular hyperbolae closely and practically up to the point of rupture. The axes of symmetry of these hyperbolae make angles of about 40° with the stress-axis in the case of pure-gum mixtures and about 30° for carbon black mixtures. A general formula has been derived which holds for all the rubbers investigated.