bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rubber. XVth Communication. The Polymerization of Rubber, Isoprene, and Styrene by Light in the Presence of Sensitizing Agents
Authors: Pummerer Rudolf , Kehlen Hans 
Published: February 2011

Abstract
Although according to Bernstein, exposure of rubber solutions to light in the absence of air diminishes the viscosity of the solutions, it is the conviction of the present authors that this change takes place only when there is air over the solutions. In 1920 Porritt observed that a rubber solution sealed off from contact with air gelatinized on exposure to light. Kirchhof however found this to be true only with small quantities of rubber solutions in quartz tubes exposed to ultra-violet light. This reaction was of particular interest to the present authors because of its possible relation to the vulcanization reaction, which can be regarded as an increase in molecular size, and as the formation of chains of rubber molecules with and without sulfur. Irradiation is perhaps an effect similar to vulcanization, but is brought about by polymerizations. It was also of interest to compare irradiated and gelatinized sol rubber with gel rubber. All the experiments described in the present paper were carried out with water-clear sol rubber, which was prepared in most cases from crepe.
The Chemistry of Soft Rubber Vulcanization. I. Measurement of Vulcanization
Authors: Garvey B. S. , White W. D. 
Published: February 2011

Abstract
For a series of rubber-sulfur compounds and for four commercial, high-gum accelerated compounds the changes during cure have been measured by a series of physical tests. The change in combined sulfur has also been measured for the rubber-sulfur compounds. Experimental conditions have been so controlled that all results are comparable. Based on the experimental results, a set of criteria has been selected with approximate limiting values for unvulcanized and for vulcanized rubber. Conditions are specified under which the criteria can be used to measure the degree of vulcanization. The selection of these criteria is, in effect, a definition in terms of the changes in physical properties which limits the meaning of the term “vulcanization” in a manner useful for the study of the phenomenon. The difference in the rate of change of the several properties is interpreted as evidence that during vulcanization a mechanical structure is built up.
Oil-Resisting Rubber
Authors: Naunton W. J. S. , Jones Maldwyn , Smith W. F. 
Published: February 2011

Abstract
From the mechanical engineer's point of view, rubber has one serious drawback, and that is the behavior toward lubricating oil. By proper compounding and curing, rubber is being used under circumstances which involve contact with oils, but there is still room for improvement. When one considers that oil-resisting rubber is finding and could find still greater application in the engineering, especially the automobile, electrical, petroleum, gas, paint, printing, agricultural, and other industries, it is not astonishing that this problem is one of the most important of the rubber industry. Little work, however, has been published on this subject prior to the present year. The popular belief that glue protects rubber against oil has been shown to be incorrect, and will be dealt with later in the paper. Ishiguro (Rubber Chem. & Tech., 6, 278 (1933)) studied a large number of fillers, soaps, glue, starch, and accelerators, but in view of the fact that the author did not make a preliminary study of the effect of these substances upon cure, the reader of the paper is left with the impression that the results are due as much to the effect of the various substances upon the state of cure as to their intrinsic oil-resisting properties. It is true that a certain amount of correction was made in the case of accelerators. The paper must, however, be welcomed as the first systematic publication based on experimental work on this subject. Karsten (Kautschuk, 9, 73 (1933)) brings out a very important point in his paper to the effect that the best method of obtaining oil-resistance in rubber must depend upon the use to which the finished article will be put: for example, large proportions of reinforcing fillers and glue cannot be used when a flexible rubber is required, and so on.
Solution Properties of Dried Rubber
Authors: Messenger T. H. 
Published: February 2011

Abstract
References to the properties of raw rubber dried to a point beyond that of ordinary commercial practice are very scanty. The Rubber Research Scheme is at present engaged in a comprehensive investigation into the factors governing the plasticity of raw rubber, and has found that humidity conditions during storage may greatly affect this property. Thus, storage in a dry atmosphere (over calcium chloride) leads to greater hardness (Ceylon Rubber Research Scheme, 2nd Quarterly Circ., 1929, p. 1), and storage in dry nitrogen (and it is presumed, in any dry inert medium) has a similar effect (Martin and Elliott, Ceylon Rubber Research Scheme, Quarterly Circ., 8, 7 (1931)). Staudinger and Bondy have used vacuum drying in their work on fractionating raw rubber (Ann., 488, 153 (1931)). Some years ago the writer had occasion to dry a small sample of rubber by passing over it at about 60° C. a stream of hydrogen dried by contact with phosphorus pentoxide. It was observed that alter drying the rubber was very difficult to bring into solution in benzene. This suggested the experiments described in the present note, which were initiated to examine the effect of thorough drying on the solution properties of raw rubber.
The Preparation of Chlorinated Rubbers from Latex. Hypochlorination and Chlorination Processes
Authors: Bloomfield G. F. , Farmer E. H. 
Published: February 2011

Abstract
With the view of extending the field of application of rubber latex, it has been considered desirable to study the behavior of this material toward various chemical reagents. Owing to the colloidal nature of latex the choice of reagent is considerably restricted; acids and many salts (especially those of bivalent and tervalent metals) produce coagulation, while alkaline reagents may cause creaming and aggregation of the particles. It is known that with the aid of certain stabilizers (e. g., saponin or casein) a stable acid latex may be obtained, but this is in general only stable over a limited range of pH values and is not stable to heat; moreover the stabilizer itself is prone to attack by the chemical reagent introduced. As would be anticipated from the foregoing considerations, the direct introduction of chlorine into latex immediately causes coagulation. Ellis and Boehmer (U. S. Patent 1,544,535) appear to have achieved some measure of success in chlorinating latex by using liquid chlorine under pressure, but the products obtained in different operations varied considerably in their properties.
Mechanism of Rubber Aging
Authors: Johnson Bernard L. , Cameron Frank K. 
Published: February 2011

Abstract
The position of the diffraction lines obtained on x-ray photographs of rubber does not change upon aging the rubber in the oven at 70° C. for 10 days. However, the intensity of the lines decreases as the aging time is increased. The increased elongation needed to produce fibering in aged rubber is considered necessary to expel the increased concentration of lower polymers, introduced by depolymerization during aging, from the crystalline aggregates or fibers allowing the latter to diffract the x-rays. Oxidation might also produce the same effect by the formation of obstacles to the stretching out of tangled molecules or micelles. The rate of depolymerization upon aging vulcanized rubber in the oven at 70° C. is studied, and a curve of the elongation at which the crystalline modification first appears is plotted against the time of aging. The same general curve is obtained for rubber both with and without phenyl-β-naphthylamine, indicating that an antioxidant such as phenyl-β-naphthylamine does not affect the rate of depolymerization of rubber or the elongation necessary to produce fibering in aged rubber.
Accelerators Derived from Piperidine
Authors: Philpott M. W. 
Published: February 2011

Abstract
Before the year 1913 piperidine was a compound of little more than academic interest and seldom to be found in considerable quantities outside the chemical laboratory. At about that time it became known that many organic bases, and in particular, piperidine and its homologs, had the effect of accelerating the vulcanization of rubber. Had piperidine then been available at a reasonable price, there is no doubt that large quantities would have been absorbed by the rubber industry. Apart from the high cost of the material, however, piperidine and other bases were not free from the objection that they were volatile and unpleasant to handle in the ordinary mixing process. In the light of modern standards, the degree of acceleration imparted by these bases would be regarded as being of a low order. In those days, however, the effect had a considerable practical significance. In attempting to make use of these bodies in a more convenient form, it was subsequently shown that the compounds formed by the reaction of carbon disulfide with aliphatic amines had an accelerating effect that was much more intense than that of the amine itself. In particular, the product obtained from the reaction of piperidine with carbon disulfide, namely, piperidyl pentamethylenedithiocarbamate (P.P.D.), was found to have exceptionally useful properties. It is probably true to say that this product was the first ultra-accelerator to acquire commercial importance.
The Swelling of Latex
Authors: Evers F. 
Published: February 2011

Abstract
The swelling of solid substances is a phenomenon which has been known for a long time, and extended investigations have been made on its nature. On the other hand the title of the present work may appear to be incongruous, for there has been in the past no evidence that liquids have any tendency to swell. At least the mutual action of two liquids has been spoken of, not as a swelling, but only as a partial mixing, i. e., as an equilibrated dispersion. Nevertheless, under certain conditions latex undergoes actual swelling. A reference to the works of Hauser and of earlier investigators on the morphology and composition of latex will show that the colloidal condition of the solid phase of latex is responsible for its remarkable behavior with hydrocarbons. Latex represents a dispersion of rubber in a serum. The rubber, in the form of latex globules, is surrounded by a layer of adsorbed protein. Besides salts and sugars, the serum contains protein. This complex composition causes the remarkable phenomenon of swelling of latex with hydrocarbons. A few years ago the author dealt with this phenomenon in a brief way. In the present work a few observations on experiments on the swelling of latex are described. The results of the investigation show that swelling in ammoniacal latex depends upon the swelling of a layer of rubber in the boundary surface.
The Vulcanization Process and the Reinforcement of Rubber
Authors: Twiss D. F. 
Published: February 2011

Abstract
The results above generally support the view that vulcanization and reinforcement are akin, and that in due time other convenient reactions than those produced by sulfur and selenium (or sulfur chloride), with rubber as the medium, will be available for both purposes. Furthermore, in that it indicates directions for future research, the “dispersion theory” of vulcanization still clearly justifies its existence.
The Use of Rubber in Paint Vehicles
Authors: Stevens H. P. , Heaton Noel 
Published: February 2011

Abstract
The fact that raw rubber swells and eventually dissolves with stirring in a number of solvents to yield a viscous, sticky solution naturally led to attempts to utilize this material for the preparation of paints and for the manufacture of adhesive and calking compounds like marine glue. It must be remembered that the raw rubber of the early days was not usually Hevea, but of lower grade containing much resin, and perished or deteriorated hydrocarbon, so that the product in a solvent was more sticky and less viscous than that which we should have in mind today. But whatever the grade, the viscosity of rubber solutions is a disadvantage, and has proved the main obstacle to the utilization of rubber in paints today. Apart from this drawback, quite a number of those technologists who experimented with rubber in paints were too optimistic as to the improvement likely to result. To many the word rubber sums up a material of “elastic” properties; and having great resistance to penetration by moisture and aqueous reagents generally, all desirable properties for a paint film; hence a proportion of rubber might be expected to impart added elasticity and impermeability. Such, however, is not the case. Complete incorporation of rubber to produce a homogeneous film is necessary to provide increased elasticity, while on the other hand rubber is not water-resistant unless vulcanized, and as vulcanization renders the rubber insoluble it cannot be used in this form. The prevalent idea that if a film of raw rubber were applied to a surface in the same manner as paint it should yield a moisture-proof coating is entirely erroneous, that is, using the word paint in the ordinary sense. it is possible to utilize rubber in this manner by compounding a solution of latex and applying the mixture to the surface to be coated, subsequently heating sufficiently to vulcanize, preferably to the ebonite state. By such means a water-resisting layer is obtained, but the process is only adaptable in special circumstances, and the materials are not of the class of paint which is now being considered.
Fibering of Rubber. Time Lag and Its Relation to Rubber Structure
Authors: Long John D. , Singer William E. , Davey Wheeler P. 
Published: February 2011

Abstract
FOR several years it has been known that in the unstretched condition ordinary rubber acts toward x-rays like an amorphous material, but that, when it is sufficiently stretched, it acts toward the rays like a fibrous material. In 1931 Acken, Singer, and Davey (1) reported that at room temperature a time interval was required to build up the fibrous structure in cyclically stretched rubber. Investigation showed that the time-lag effect could not be accounted for in terms of a temperature change during the act of stretching. Even if all the mechanical energy of stretching were instantaneously changed into sensible heat, the temperature of the rubber sample could not have been increased momentarily by more than 5.2° C., whereas the fibering of rubber continuously stretched at 420 per cent elongation could be demonstrated up to a temperature of 47° C. Experimentally no temperature rise greater than 1.0° C. could be found in the samples used. Since the time-lag effect appeared, therefore, to be a real effect, it seemed worth while to study it in detail. It is the purpose of this paper to report: (1) typical data on the effects on the time lag, of temperature, previous temperature history, mechanical working and aging, time of relaxation, time of stretch, and rate of stretch; and (2) the relation of these results to the possible structure of the rubber fiber.
A Shearing Disk Plastometer for Unvulcanized Rubber
Authors: Mooney Melvin 
Published: February 2011

Abstract
AN IDEAL plastometer for unvulcanized rubber would give a precise measurement of plasticity, would complete a measurement in 30 seconds or less, and would be sufficiently simple in operation to be used by an unskilled mill-hand. In an effort to develop such an instrument, a number of instruments, operating on a variety of different principles, were built and tried out; but none was found that would satisfy all the above criteria. Precision being considered a matter of primary importance, it was then felt that the only alternative was to develop a plastometer that would be as simple and as quick in operation as it could be and still remain accurate. The shearing plastometer described below was the result.
The Structure of Gutta-Percha Based on Studies with Electron Rays
Authors: Bruni G. , Natta G. 
Published: February 2011

Abstract
Among the natural organic compounds with high molecular weights which have been the object of roentgenographic investigations with a view to determining their intimate constitution, rubber and other hydrocarbons of similar constitution such as gutta-percha and balata have been extensively studied in recent years. The results obtained with these substances by x-ray methods have however not been so complete and reliable as in the case of other products with high molecular weights, such as cellulose, found in nature in ramie and in certain vegetable fibers in forms which are particularly well oriented, which is of enormous advantage in structural investigations. Nevertheless, the roentgenographic results on rubber are of the greatest interest because from them it is possible to show that the molecules of rubber are oriented when the rubber is stretched or frozen, so that it can be proved that under these special conditions it has a sort of crystalline structure which is characterized by definite identity periods. The determination of the identity period in the direction of the fibers, which is 8.1 A. U., is particularly reliable.
The Viscosity of Latex
Authors: Bary Paul 
Published: February 2011

Abstract
Latex, like most emulsions, has complex properties which make its use at times difficult because of somewhat unexpected phenomena which take place within the mass. The properties of this material, whose usage is spreading more and more, are therefore of practical interest, and this has led us to publish the results of some investigations on the viscosity of latex and the conclusions which seemed to be justified by these experiments. The viscosity of a normal latex containing 38 per cent of rubber is about 4.6 times as great as that of water. This is true of a latex containing a little ammonia, such as the grades which can be purchased in France. The same latex, concentrated to 60 per cent, or “Jatex,” is almost 42 times as viscous as water, i. e., more than 10 times as viscous as 38 per cent latex. Moreover, if latex of different concentrations is prepared by dilution of 60 per cent latex, it is found that the viscosities are those given in the accompanying table, expressed as relative viscosities, based on the viscosity of water.
Some Observations on Accelerator Practice and Modern Compounding
Authors: Davies R. C. 
Published: February 2011

Abstract
In the last twenty-five years a number of complex organic compounds have been developed and patented for the purpose of accelerating the vulcanization of rubber. Really serious bulk usage throughout the trade, however, did not commence until after the war. Research in this field raced ahead of manufacturing progress and brought out accelerators which were so active that they were almost unusable. There are now accelerators which are more than sufficient for the needs of the moment. They cover all ranges of conditions, such as slow, medium slow, semi-fast, semi-ultra, ultra, and super-ultra accelerators. In addition there are modifications for delayed action, quick start, flat peak, high tensile, and superflexing; also accelerators which will cure without heat and others which will cure without added sulfur. In view of the publicity indulged in by the vendors, one might almost feel compelled to change one's accelerators every week. Rationalization is as necessary in the use of accelerators as in the use of fillers. In the wise use of accelerators it is necessary to make a careful selection of only a few which function best in the temperature and process range of any particular manufactures.
Colloidal Changes during Rubber Vulcanization
Authors: Williams Ira 
Published: February 2011

Abstract
RUBBER is colloidal in nature and colloidal phenomena should be expected to play a part in the decrease of plasticity which is recognized as vulcanization. The elasticity of vulcanized and unvulcanized rubber is substantially the same (23), and it is probable that elasticity is a function of the molecule while plasticity is a function of the state of aggregation. Many authors have suggested that either disaggregation or depolymerization is one step in vulcanization (1, 8, 15, 16, 19). Other authors believe that aggregation or polymerization is a factor (2, 4, 6, 9, 10, 13, 14, 18, 19, 21, 22). In many cases it is probable that the term “polymerization” or “depolymerization” is used loosely and is not intended to involve a change in unsaturation. Ostromislensky (12), Stevens (17), and Twiss (20) have suggested that vulcanized rubber contains the reaction product of rubber and sulfur dispersed through the rubber as fine particles or threads. Feuchter (5) suggests a similar although somewhat more complicated system which includes accelerator. Whitby (21) concludes from his experiments with drying oils that accelerators act on rubber containing combined sulfur to produce gelation or polymerization. Stevens and Stevens (18) have milled zinc oxide and accelerator into acetone-extracted vulcanized rubber and find that heating produces further vulcanization.
New Results on the Ozone Decomposition of Natural Rubber and of Sodium Butadiene Rubber
Authors: Pummerer R. 
Published: February 2011

Abstract
The method of Harries for the ozone cleavage of unsaturated organic compounds has shown its first important results in the case of rubber. Surprising as it may seem, however, there has been no attempt until now to follow the course of this reaction by bromine titration. When this is carried out, a very surprising result is obtained. It was to be expected that, corresponding to the addition of ozone to the double bonds, there would be an equivalent decrease in the bromine titre. However, such is not the case. If a one per cent solution of rubber in chloroform is ozonized at 0° and samples are removed from time to time and titrated dropwise with bromine solution until the yellow coloration persists for 10 minutes, it is found that the consumption of bromine for the first one to two hours undergoes no essential decrease as a result of the introduction of ozone. If the titration is continued, a rather rapid diminution begins at the time when free ozone can be detected in a potassium iodide solution placed beyond the ozone vessel. The curve then descends sharply to zero. Closer study of the process by the titration method of MacIlhiney, which also makes it possible to collect the hydrogen bromide formed, has shown us that in the case of rubber the apparent initial constancy of the bromine consumption is explained by the fact that there is an ozonide replaceable by bromine, and accordingly that the bromine number represents substitution and addition, whereas under the above conditions (10 min. at 0° C.) the original rubber solution in chloroform shows only addition. The ozonide which reacts with bromine may be termed a primary ozonide, and that which is formed later and is stable toward bromine may be called an isozonide. This name originated with Staudinger, who pointed out nine years ago that in the ozonization of olefins it is possible that “molozonides,” or, as we now say primary ozonides, of very unstable type are first formed, which still contain the added molecule of ozone (Formula I) whereas the ordinary end products of ozonization are formed by rearrangement and are to be called isozonides (Formula II). This was concluded by Staudinger from the known behavior of the ozonide in the reduction, which never yields 1,2-glycol but a cleavage of the carbon chain instead. The formation of polymeric ozonides together with quite stable monomers, which are not converted into polymers, is further evidence of this.