bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vulcanization of GR-S by the Peachey Process
Authors: McPherson Archibald T. 
Published: February 2011

Abstract
It has been found possible to vulcanize GR-S synthetic rubber by subjecting it alternately to hydrogen sulfide and sulfur dioxide gases. This method for curing, known as the Peachey process, was used for natural rubber as long ago as 1921. A simple apparatus was constructed, in which strips of thinly milled rubber were placed on a screen inside a glass tube. One end of this tube was attached to valves connecting it to tanks of hydrogen sulfide, sulfur dioxide, and air, respectively. The other end of the tube led to a series of traps containing solutions which absorbed or destroyed the gases. For each test performed, natural rubber samples were placed inside the tube along with the GR-S samples for comparison. Each strip was weighed before it was inserted in the apparatus. Hydrogen sulfide was first slowly passed over the samples for a period of five minutes. Then air was blown through for a few seconds—just long enough to free the surroundings from the sulfide gas, but not long enough for the gas to be lost from solution in the rubber. Sulfur dioxide gas was next admitted and allowed to pass over the samples for five minutes. A subsequent short sweep of air through the tube completed one cycle of the curing process.
Plasticizers in Rubbers and Plastics
Authors: Jones H. 
Published: February 2011

Abstract
Up to the advent of synthetic high polymers, plasticizer technology was little understood, Plasticizers had been used mainly with cellulose derivatives, which are not at all good materials for the study of plasticizer action. The chemical processing they undergo, e.g., nitration, acetylation, etc., leads to variations on account of irregular chemical action. In addition, these materials are partly crystalline and partly amorphous. The growing numbers of new materials brought a host of problems in their train, and plasticizing was not the least of them, but a study of their behavior with plasticizers has advanced the knowledge of the plasticizer-polymer system. The principal advances have come from a study of regular and amorphous polymers, such as polyvinyl chloride, polyvinyl acetate, polystyrene, butadiene rubbers, and so on. From knowledge of these materials, one can revert to the consideration of irregular polymers such as cellulose derivatives and those produced from high polymers by additional chemical reaction, with a better likelihood of understanding their behavior with plasticizers. Thus the recent extensive use of plasticizers has led to an improved understanding of their action, and it appeared that a paper dealing with the subject might be acceptable.
Sodium-Catalyzed Copolymerization of 1,3-Butadiene and Styrene
Authors: Marvel C. S. , Bailey W. J. , Inskeep G. E. 
Published: February 2011

Abstract
1. A convenient laboratory procedure for the sodium-catalyzed copolymerization of butadiene and styrene has been described. Earlier attempts to accomplish this probably failed because the monomers were not sufficiently pure. 2. The copolymer of butadiene and styrene which results from sodium polymerization is different from the emulsion copolymer, GR-S, in several important respects. The sodium-catalyzed copolymer has a more nearly constant styrene content at different stages of conversion; it is made up of molecules with a relatively narrow molecular weight spread; it has a higher intrinsic viscosity; it is 100 per cent soluble in benzene (i.e., there is no gel) even at 100 per cent conversion; when treated with standard rubber antioxidant, it ages better; and it has a greater amount of the butadiene joined in the 1,2 manner (i.e., greater vinyl side-chain content). 3. The effects of such variables as temperature of polymerization, method of adding the monomer mixture to the catalyst, size of catalyst particles, and possible butadiene impurities on the polymerization have been studied. 4. The method has been extended to cover copolymerization of butadiene and m-methylstyrene to give a soluble copolymer of low molecular weight. Other styrene-type monomers gave less interesting copolymers.
Effect of Carbon Blacks on the Physical Properties of Natural Rubber and Neoprene-GN
Authors: Buist J. M. , Mottram S. 
Published: February 2011

Abstract
1. All the blacks tested can be incorporated into Neoprene-GN much more easily than into natural rubber, and the limits of loading are higher with Neoprene-GN than with natural rubber. 2. A broader maximum in the tensile strength-volume loading curve is obtained with Neoprene-GN, and it has been found that the two coarse blacks do not reinforce Neoprene-GN. 3. Tables show the grading of each carbon black with each physical property. It has been found that, in general, the results correlate with measurements of particle size and surface area. 4. Even so, if dynamic conditions are met in service, it is necessary to evaluate the degree of reinforcement under dynamic conditions. 5. With natural rubber, each black tends to have its own correlation between dynamic and static hardness tests, whereas with Neoprene-GN one correlation exists for all blacks. 6. Within a given polymer it is sufficient to do only compression plasticity (Williams) measurements, and recovery measurements are required only when comparing different polymers. 7. Measurements of tear resistance with Neoprene-GN have shown that, as the particle size of the blacks decreases, the peakiness of the tear resistance volume loading curve is increased, particularly at higher temperatures. 8. Torsional resilience and impact resilience have a very high correlation in natural rubber. 9. Different carbon blacks in Neoprene-GN produce very small changes in resilience. 10. With increased loadings of black the resilience properties of both rubbers become more sensitive to temperature. 11. On both the du Pont and Dunlop abrasion machines, there is fairly good agreement between abrasion resistance and particle size. 12. With natural rubber, if the hardness is maintained constant and resilience increased, the heat build-up decreases, whereas with Neoprene-GN under the same conditions the heat build-up increases. 13. When comparing compounds of different hardness for heat build-up, a constant deformation test is preferable to a constant load test. 14. There is a good correlation between swelling in benzene and modulus measurements. The correlation is better with Neoprene-GN than with natural rubber.
Styrene-Diene Resins in Rubber Compounding
Authors: Borders A. M. , Juve R. D. , Hess L. D. 
Published: February 2011

Abstract
Early in the investigation of butadiene-styrene copolymers as synthetic rubbers, this laboratory became interested in copolymers containing much more styrene than any of the American or German synthetics. This interest was soon directed to the resinous copolymers obtained when the styrene content is increased beyond the range in which rubberlike properties are observed at room temperature. The exploratory work, therefore, involved preparation and evaluation of butadiene-styrene copolymers containing from 65 to 98 per cent styrene. No description of similar polymers has been found. Konrad and Ludwig claimed the improvement of rubberlike properties of butadiene-styrene copolymers by increasing the styrene content from the normal range to “between about 47.5 and about 70 per cent”. The claims and examples of this patent emphasize the improvement of rubberlike properties, such as tensile, elongation, and rebound, at high temperatures. It is well known in this country, however, that increase in styrene content beyond a certain point, perhaps 50–55 per cent, is accompanied by a loss of overall balance of rubber characteristics. Therefore, the copolymers at the upper end of the range described by Konrad and Ludwig have definite limitations for rubber uses—for example, low rebound, high brittle point, shortness, etc. In the writers' laboratory useful resins have been prepared from dienes and vinyl aryl hydrocarbons in the range 5 to 20 per cent diene and 80 to 95 per cent vinyl aryl hydrocarbon. This paper describes the properties and certain uses of one of these copolymers containing approximately 15 parts of butadiene and 85 parts of styrene. This material possesses a combination of physical and chemical properties which permit its use in several applications where cyclized natural or synthetic rubbers are commonly employed. Cyclized natural rubber has been described by Bruson, Endres, and Thies and Clifford. Cyclized synthetic rubbers were described recently by Endres. One product of this type is made from a special synthetic rubber. The new 15 butadiene—85 styrene copolymer is now identified as Pliolite S-3, since it may be used in many Pliolite applications, often with distinct advantages over either the natural or synthetic rubber derivatives.
The Thermoplasticity of Chlorinated Rubber
Authors: Lepetit F. 
Published: February 2011

Abstract
Among the various factors which play a part in the chlorination of rubber, the percentage of combined chlorine, the temperature of chlorination, and the degree of mastication have pronounced effects on the thermoplasticity of the final chlorinated rubber products. By taking advantage of certain operating conditions which are suggested by the work described above, it is possible to obtain a chlorinated rubber with relatively low thermoplasticity. It does not appear to be possible by these means to reduce to any significant degree the thermoplasticity of chlorinated rubber, without perhaps the use of operating conditions which would be difficult to control, e.g., chlorination under pressure or at high temperature.
Abrasion Tests on Rubber
Authors: Lewis T. R. G. 
Published: February 2011

Abstract
Although the abrasion machine to be described has been used in the laboratories of the British Boot, Shoe and Allied Trades Research Association for many years, there has been no publication of a description, nor any account of its performance. The original machine has been modified by the incorporation of an efficient suction device, and redesigned structurally, though still employing the same basic mechanism. Experiments have been carried out on large numbers of war-time substitutes for soling-leather, rubber-soling materials with reduced rubber content, for containing GR-S, and new plastic materials and synthetic rubbers. The machine has been found to give reproducible figures, quickly and under easily controlled conditions, and the results have been of value for comparing various materials. No attempt is made in this paper to judge the significance of these figures or to correlate them with actual wear data.
GR-S Emulsified with Rosin Soap
Authors: Cuthbertson G. R. , Coe W. S. , Brady J. L. 
Published: February 2011

Abstract
One of the most troublesome deficiencies of standard GR-S, in so far as product fabrication is concerned, is the inherent lack of tackiness or the incapability of laminated and spliced surfaces to flow and knit together easily. This was especially bothersome from 1942 to 1944, when the scarcity of natural rubber forced fabricators to use a synthetic polymer before they had developed satisfactory methods and equipment to compensate for its deficiencies. Early in 1942, in anticipation of a later scarcity of fats and oils suitable for making the soap used for emulsification, the several groups working on polymer development problems intensified their efforts to find emulsifying agents which could be made from noncritical domestic materials. Rosin was one of these. Early attempts to use it were unsuccessful, however, because the polymerization reaction was strongly retarded. Later the Hercules Powder Company and The B. F. Goodrich Company, working together, found that the retarding effect could be greatly reduced with the use of disproportionated rosin previously referred to as dehydrogenated rosin. (The treatment given to the rosin results in a molecular disproportionation of the hydrogen, with the elimination of the conjugated double bonds accountable for much of the inhibiting effect on the polymerization reaction.) This work made rosin available for use in the event of an actual scarcity of fats and oils of good quality.
Tear Resistance. More Accurate Results Using I.C.I. Tear Cutter
Authors: Buist J. M. , Kennedy R. L. 
Published: February 2011

Abstract
(1) A new tear cutter has been designed which is capable of easy and rapid operation for routine work. (2) Using the new cutter accurate work is possible, and the error in tear resistance results has been reduced to the same order as that obtained with tensil strength determinations. (3) It is recommended that a tolerance value of ±3 thousand inch be placed on the 0.02-inch depth of nick. (4) It is also recommended that six test-pieces be used, and the median of the results recorded. (5) The observation is made that the angle-tear test is a measure of tear initiation and can, therefore, be considered an addition to the crescent-tear test, which is a measure of tear propagation.
Statistical Evaluation of Variations in Rubber Processes and Correlation in Physical Properties
Authors: Buist J. M. , Davies O. L. 
Published: February 2011

Abstract
The scope for the application of statistics to the field of rubberlike rnaterials is extensive, and various authors have already used statistical methods. Statistical methods derive the maximum amount of information from the results of an investigation, and at the same time supply a means of assessing the reliability and value of the information extracted. The effect of a variety of different blacks at various volume loadings on the properties of natural rubber and Neoprene-GN have been described. In the present paper the data are examined from other points of view, viz., the reproducibility of the results and the relations between the various properties. The main purpose of these investigations was to obtain the technological information already reported. At the same time, however, the program was designed as far as practicable to give information on the testing errors. Further useful information on the relation between the properties could be obtained by the application of the methods of statistical analysis. The program of experimental work with natural rubber covered a period of three months (November 1940–February 1941) and, to obviate as far as possible variations in the raw material, a quantity sufficient for the whole program was master-batched at the outset. The carbon blacks used were from normal supply, but special quantities were kept for this program. In 1942 a similar program was carried out with Neoprene-GN. The details of the mixes used, mixing procedure, and conditions of curing, have been given previously. Each mix was repeated three times on different days, and repeat determinations on the physical properties were carried out.
The Mechanism of Modifier Action in the GR-S Polymerization. I
Authors: Snyder H. R. , Stewart John M. , Allen R. E. , Dearborn R. J. 
Published: February 2011

Abstract
When butadiene and styrene are copolymerized in an aqueous emulsion containing only the monomers, an emulsifying agent, and a peroxidic catalyst, the product obtained is an insoluble substance which is difficult to process and is of little value as a rubber. Useful copolymers are obtained by adding to the polymerization system a substance known as a “modifier”. In the preparation of GR-S, the modifier used is a thiol or a mixture of thiols. The copolymer produced in the presence of such a modifier is soluble in benzene, and it can be milled and processed much like natural rubber. The present work was undertaken in an effort to determine the nature of the chemical action of the modifier. It is now generally believed that vinyl polymerizations induced by peroxidic catalysts proceed by a free radical mechanism in which the essential steps are initiation, propagation, and termination. Peroxide-catalyzed polymerizations of dienes differ from those of simple vinyl monomers in that the steps of initiation and propagation may consist in either 1,4- or 1,2-addition to the diene system, or both 1,4- and 1,2-addition may occur in random fashion. Ozonization studies of polybutadiene indicate that the polymer has a structure of the third type, resulting from both 1,4- and 1,2-addition.
Vulcanization Testing of Reclaim. Relation between Results Obtained in Reclaim-Sulfur and Tire-Tread Mixes
Authors: Moakes R. C. W. , Scott J. R. 
Published: February 2011

Abstract
Literature on the value of the reclaim-sulfur test mix as a criterion of the quality of reclaim is briefly discussed, as a result of which the general conclusion is reached that such a mix is unreliable. This point is further studied by experiments on several reclaims made by the alkali, thermal, neutral, and other processes. The tensile strengths of the reclaim-sulfur mix and of a degraded tire-tread mix (80:40 new rubber/reclaim ratio) definitely tend to run parallel, so that, for instance, a reclaim showing over 1,000 lbs. per sq. in. in the former mix would be unlikely to give a really bad tensile strength in the tread mix, and one showing 300 lbs. per sq. in., or less would be equally unlikely to give a good strength. The reclaim-sulfur mix, however, is only a rough guide, because reclaims shown to be alike by this mix may give very different properties in the tread mix. Other properties of the reclaim-sulfur mix (breaking elongation, modulus, hardness) give no information as to the behavior of the reclaim in a tread mix; neither do the tensile properties of the former give much help in predicting how the tread mix withstands abrasion and flexing. Accelerated aging tests on reclaim-sulfur vulcanizates are of little value, except that a rapid fall in tensile strength would cast suspicion on the reclaim. These results, emphasizing as they do the uninformative nature of reclaimsulfur test results, suggest that, whenever possible, reclaims should be tested in the type of mix in which they are to be used, rather than in an arbitrary standard mix. The dependence of abrasion and flexing of the tread mix on its tensile properties is examined. Abrasion-resistance is not obviously related to these properties, but flex-cracking resistance shows a parallelism with tensile strength and especially with breaking elongation. The data are consistent with the view that the latter is the dominant factor in determining flexing life, and that the substitution of reclaim for new rubber in a tread mix does not affect flexing life except through its influence on breaking elongation; it is not yet demonstrated whether elongation directly determines the flexing life, or whether both are functions of some third property.
The Determination of Copper in Crude Rubber
Authors: Cassagne Paul 
Published: February 2011

Abstract
All types of rubber contain some copper. Although the proportion is in general extremely low, it is well not to disregard it, for this element acts as a catalyst which has a deleterious effect on the aging of rubber. For rubber to age satisfactorily it should contain not more than 1.5 mg. of copper per 100 grams of rubber; hence the interest in any method for determining the copper content of crude rubber. PRESENT METHOD The method used thus far is based on the color reaction which sodium diethyldithiocarbamate gives with a very dilute copper solution. According to the method of the British Standards Institution, the ash is treated with hydrochloric acid, and the metals of the iron group are then precipitated by ammonia. After solution of the precipitate in hydrochloric acid and reprecipitation by ammonia, the filtrate is brought to the boiling point and finally is diluted to a known volume. This solution is then used for a colorimetric determination. As a result of numerous experiments with crude rubbers from different sources in which the method described above was used, it has been found that the reagent called for in this method is not specific enough; in fact it gives a color reaction with metals other than copper, notably with iron, manganese, zinc and heavy metals which cannot be separated reliably by the ammonia method. There would seem to be two solutions to this problem; either to develop another method which employs a reagent having a more specific action, or to improve the currently used method of the British Standards Association in such a way as to eliminate the disturbing ions.
Comparison of Ultraviolet Absorption and Chlorine Analysis Methods for Composition of Butadiene-p-Chlorostyrene Copolymers
Authors: Meehan E. J. , Parks T. D. , Laitinen H. A. 
Published: February 2011

Abstract
The percentage of chlorine in a copolymer containing chlorostyrene can be determined by amperometric titration of the chloride ion present after sodium fusion of the polymer. Since the percentage of chlorine is proportional to the percentage of chlorostyrene, the composition of a butadiene—chlorostyrene copolymer may be determined directly. This absolute method of composition determination affords a means of checking the ultraviolet spectrophotometric method which has been proposed for the determination of the composition of butadiene—styrene copolymers. In the application of the spectrophotometric method it is assumed that the specific extinction coefficient of the copolymer varies linearly with the percentage of styrene between the values of the same wave length for polybutadiene and polystyrene. The spectrophotometric measurements are made at 260.0 mµ or at 269.5 mµ for copolymers of butadiene with styrene or with p-chlorostyrene, respectively.
Comparison of the Bromine and Nitric Acid Methods of Estimating Sulfur in Acetone Extracts
Authors: Morley J. F. , Scott J. R. 
Published: February 2011

Abstract
From the experiments described, it appears that neither the bromine method nor the nitric acid method is perfectly satisfactory, for the following reasons. (1) Neither method gives the true free sulfur in rubbers containing sulfur-bearing accelerators, as these cause positive errors of anything up to 0.2–0.3 per cent. (2) The nitric acid method does not give the true free sulfur in rubbers, without sulfur-bearing accelerators, because the result includes some of the sulfur combined with the rubber “resins” the tests do not show definitely whether this applies also to the bromine method. (3) Neither method gives the total sulfur in the acetone extract, since some of the sulfur combined with the “resins” is not included in the result; the presence of certain sulfur-bearing accelerators increases the error. The statement previously referred to (loc. cit.), that the bromine method approximates more nearly to the elementary sulfur content and the nitric acid method more nearly to the total sulfur content of the extract, appears to be a correct generalization. In most cases, however, the difference between the results obtained by the two methods would be less than 0.1 per cent. In respect of simplicity and rapidity of working, the bromine method has the advantage over the nitric acid method, and therefore in all ordinary circumstances is the one to be recommended.