bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproducibility of Tensile, Permanent Set, and Hardness Test Results in the Same Laboratory
Authors: Morley J. F. , Porritt B. D. , Scott J. R. 
Published: February 2011

Abstract
1. An investigation has been made into the accuracy with which measurements of tensile strength, breaking elongation, elongation at constant load, modulus, permanent set, and hardness can be repeated on successive days, using specimens taken from the same sample of rubber. 2. There is evidence that the gradual blunting, during normal use, of the knives used for cutting ring or dumb-bell specimens may appreciably reduce the tensile strength of the specimens. 3. After allowing for the apparent effects of blunting, aging of the rubber, and day-to-day variations in test temperature, the variability of the results has been examined by determining (1) the variability within each day's results (standard deviation of individual results); (2) the variability among the means of different days' results (observed standard error of daily means); and (3) the variability of daily means that would be expected to arise from (1) (calculated standard error of daily means). 4. In nearly every case the observed error of the daily means is greater than calculated value, showing that the results are affected by some factors (other than those already allowed for) that vary from day to day. It is not possible at present to say definitely what these factors are, although two causes of variation are suggested. In many cases, however, particularly with tensile strength and breaking elongation, a considerable part of the variation among daily means can be ascribed to the variation among individual results obtained on one day. 5. Examination of the frequency distribution of the tensile strength results shows that the majority (90–98 per cent) usually form a substantially symmetrical curve of the normal type, the remainder being abnormally low values, though not necessarily unreliable values. If the low values are excluded, the standard deviations and (in most cases) standard errors are reduced, but the conclusions deduced from them remain substantially unchanged.
Statistical Control in the Physical Testing of Rubber
Authors: Heide J. D. 
Published: February 2011

Abstract
In conclusion, may I repeat that the statistical methods find a useful and important application in the control of physical testing of rubber. An attempt has been made to show how the physical testing of rubber might yield more useful information if these methods were adopted. The illustrations and examples given have been of a very general nature. It is hoped, however, that they are of sufficiently fundamental nature to point the way to specific uses in any laboratory.
A Viscometer for Measurements during Thixotropic Recovery. Results with a Compounded Latex
Authors: Mooney M. 
Published: February 2011

Abstract
A viscometer is described for measuring the viscosity of a liquid immediately after an abrupt reduction of the shearing stress to a very low value. A hollow cylinder on a torsion suspension is immersed in the liquid contained in a narrow annular channel. The inner wall of the channel is rotatable with respect to the outer wall, and by this rotation the liquid is stirred or sheared. After the stirring is stopped, the viscosity is measured by recording photographically the rotation of the hollow cylinder, driven by a nearly constant torque applied through the torsion suspension. Measurements were made on a commercial compounded rubber latex containing 47.5 per cent of total solids. Immediately after stirring, the latex is a Newtonian liquid with a viscosity of 0.05 poise. Thereafter the viscosity increases at an initial rate and to an ultimate value, both of which decrease as the shearing stress for measuring the viscosity is increased. The steady viscosity is attained approximately in 10 seconds. The observed extremes in steady viscosity were 11 and 0.5 poise, corresponding to the shearing stresses 1.3 and 10.7 dynes per sq. cm. The experimental data are fitted approximately by theoretical curves based on these assumptions. All aggregates of solid particles are broken up by the stirring. During subsequent thixotropic recovery, loose aggregates are formed which contain considerable trapped water. The rate of aggregation follows Smoluchowski's theory of slow coagulation, but both the coagulation rate constant and the percentage volume of water in the coagulates vary with the applied shearing stress. The relative viscosity of the suspension of aggregates follows an empirical law based on Eilers' data on aqueous suspensions of bitumen spheres.
The Measurement of the Adhesion of Unvulcanized Rubber to Metal
Authors: Blow C. M. 
Published: February 2011

Abstract
A method is described for measuring the adhesion of metal to unvulcanized rubber and rubberlike materials, which involves the observation of the angle at which a metal ball rolls off the rubber surface when it is tilted. Experimental results are given to confirm the theoretical basis of the method and to illustrate the value of the method in studying the processing characteristics of rubber compounds.
A Method for Preparing Rubber Latex Specimens for the Electron Microscope
Authors: Kelsey R. H. , Hanson E. E. 
Published: February 2011

Abstract
The preparation of natural and synthetic rubber latex specimens for examination with an electron microscope is difficult because the individual particles are easily deformed and, under the usual conditions of specimen preparation, the particles tend to agglomerate. Von Ardenne and Beischer and others used a method which consisted of depositing a drop of highly diluted latex on a collodion film and allowing the drop to dry completely. In some instances the drop was withdrawn again into a glass capillary. It was found that in either case the latex particles were flattened at their areas of contact with the collodion film. The collodion film method was tried in this laboratory with the same poor results observed by Hendricks, Wildman, and McMurdee. Figure 1 is an electron micrograph of a natural rubber latex particle deposited by evaporating latex diluted 200 to 1 on a collodion film. The film has broken and curled to give a profile view of the particle which is observed to be badly flattened at its area of contact with the film. Figure 2 is a typical electron micrograph of natural rubber latex particles deposited on a collodion film. The blurred outlines of the particles are explained by the effect shown in Figure 1. It was obviously impossible to make good particle-size measurements from micrographs of this type. It was found further that severe aggregation of particles usually took place when a drop of the diluted latex was dried down. The latex particles which were left behind when the drop was removed with a glass capillary usually were not badly agglomerated, but it was felt that there was some possibility that the latex particles might adhere selectively according to size to the collodion film. An attempt was made to reduce the amount of agglomeration by incorporating in the diluting water various amounts of such wetting or dispersing agents as sodium oleate, orvis paste, Aerosol-OT, and ammonium caseinate. None of these materials helped very much in reducing the agglomeration of particles. It was found also in this study that very often the latex particles appeared granular around their edges due to foreign material being swept in during the evaporation of the water and crystallizing out upon the surface of the particle. This effect may also be observed in Figure 1.
Kinetic Studies in the Chemistry of Rubber and Related Materials. II. The Kinetics of Oxidation of Unconjugated Olefins
Authors: Holland J. L. , Gee Geoffrey 
Published: February 2011

Abstract
A brief review is given of kinetic work on the oxidation of representative mono, 1,4 and 1,5 olefins. The essential process in each case is identified as a chain reaction in which hydrocarbon radicals are formed, absorb oxygen, and then react with another molecule of olefin to give a hydroperoxide and a new free radical. Three methods of chain initiation are considered: (1) direct attack of oxygen on the olefin, (2) thermal decomposition of the hydroperoxide, (3) thermal decomposition of added benzoyl peroxide. Chain termination results from interaction of two free radicals; except at low oxygen pressures, these are both peroxidic.
Sulfur Bond in Vulcanizates Implications of Halogen Reactions
Authors: Olsen S. R. , Hull C. M. , France Wesley G. 
Published: February 2011

Abstract
1. When iodine chloride is used for the determination of double bonds in sulfur-vulcanized rubber or GR-S, it undergoes side reactions induced by combined sulfur. 2. Bromine in carbon tetrachloride is believed to give a satisfactory measure of the double bonds in a rubber-sulfur vulcanizate dissolved in dichlorobenzene-chloroform mixture. 3. The relation of one double bond consumed per sulfur atom combined in the rubber-sulfur type vulcanizate was confirmed. 4. Organic accelerators (in the absence of metal activators) catalyze the combination of sulfur without altering the ratio of one double bond loss per sulfur atom combined. 5. The introduction of a metal oxide or soap, such as zinc, causes a different type of vulcanization, which results in less than one double bond consumed per sulfur atom combined. 6. The reactions of propyl sulfide, dodecyl sulfide, propyl disulfide, allyl sulfide, methallyl sulfide, and butylmethallyl sulfide with iodine chloride and with bromine, respectively, are described. 7. The behavior of rubber-sulfur vulcanizates resembles that of butylmethallyl sulfide in reactions with iodine chloride and bromine, respectively; this suggests an alkyl-allyl type sulfur bond. 8. The theory of vulcanization proposed by Armstrong, Little, and Doak, based on the α-methylenic concept of Farmer, is supported by the findings of this investigation.
Mineral Sulfide as Index of Disulfide Cross-Bonding
Authors: Hull C. M. , Olsen S. R. , France Wesley G. 
Published: February 2011

Abstract
1. The mechanism proposed by Armstrong, Little, and Doak to explain sulfur vulcanization in the presence of metal soap was investigated in polyprene and simpler systems from the viewpoint of the inorganic sulfide produced and, in the case of polyprenes, of the accompanying modulus. 2. Dodecanethiol was found to react with sulfur and zinc soap to produce inorganic sulfide equivalent to the oxidation of 80 to 100 per cent of the thiol to disulfide ; with excess thiol substantially quantitative conversion of sulfur or of zinc soap to inorganic sulfide can be obtained. 3. Several simple olefins were found to react readily with sulfur and zinc soap under vulcanizing conditions. The reaction is promoted by M.B.T. On the basis of the mechanism assumed, the inorganic sulfide formed is sufficient to indicate extensive conversion of the olefin to a substituted diallyl disulfide. 4. Assuming the validity of the proposed mechanism, inorganic sulfide production indicates substantial disulfide cross-linking between α-carbon atoms in conventional cures with natural rubber, and appreciable, though relatively less, cross-bonding of this type in the case of GR-S. The smaller extent of this type of cross-linking with GR-S is believed to result from greater tendency on the part of this elastomer to add the intermediate mercapto compound to double bonds, as proposed in the first paper of this series.
Chemical Derivatives of Synthetic Isoprene Rubbers
Authors: D'Ianni I. D. , Naples F. J. , Marsh J. W. , Zarney J. L. 
Published: February 2011

Abstract
Natural rubber was the subject of intensive investigation with respect to its chemical reactions and the preparation of commercially useful derivatives. General reviews in this field have been written by Fisher, Schidrowitz, Jones, Sibley, Memmler, Dawson and Schidrowitz, and Farmer. Before World War II several of these reaction products, such as rubber hydrochloride (Pliofilm), isomerized rubber (Pliolite), and chlorinated rubber (Parlon), had been marketed successfully. During the past five years drastic restriction of the commercial use of natural rubber for chemical derivatives prompted the study of synthetic rubbers for this purpose. Endres recently reported on chlorinated and cyclized synthetic lubbers, with special emphasis on GR-S as the starting material. This paper deals particularly with derivatives of polyisoprene and other isoprene-containing synthetic rubbers which behave chemically very much like natural rubber because of the similarity in structure. It is shown that GR-S and other butadiene-containing synthetic rubbers, under the same conditions, are either nonreactive or behave differently. Because of its similarity to the natural rubber product, isomerized synthetic polyisoprene has been designated Pliolite S-1. Chlorinated synthetic polyisoprene is referred to as Pliochlor.
Observations on the Action of Unsaturated Compounds on Rubber in Solution
Authors: Compagnon Patrice , Delalande André 
Published: February 2011

Abstract
At the time Le Bras and one of the present authors pointed out the possibility of combining unsaturated compounds with rubber in the form of latex or by an ordinary mixing operation, reference was made to an interesting work, published by Bacon and Farmer in 1938, in which these authors described the addition of maleic anhydride to rubber in solution. At the same time it was emphasized, and this point was taken up in more detail in a later publication of Le Bras, that there are essential differences between the products obtained by the two methods, both with respect to their appearance and their properties, according to whether the technique employed is emulsion or mixing, or is that described by Bacon and Farmer. It should be borne in mind that the most distinguishing feature is that the first type of product is always to a great extent insoluble in solvents of rubber, whereas the second type of product may still be soluble even when 10–15 per cent, for example, of maleic anhydride has become fixed by the rubber. However, in spite of the products differing in certain attributes, the reactions involved in these two different experimental techniques should be fairly similar. Accordingly, in attempting to increase the action of these reagents on rubber, both in the form of latex and in solid admixture, and to throw further light on the mechanism of the reaction, the present authors have studied the effect of the reagents under the operating conditions employed by Bacon and Farmer, i.e., in solution. In what follows, various observations are reported which may contribute to a better understanding of certain peculiarities of this last type of reaction and to its wider application.
The Variation of Composition of 40 : 60 Isoprene-Styrene Copolymers with Conversion
Authors: Dyer Elizabeth , Munroe Dorothy Levis 
Published: February 2011

Abstract
There is little published work dealing with the emulsion copolymerization of isoprene and styrene. In ascertaining the effect of varying conditions on the emulsion copolymerization of a 40:60 mixture of isoprene and styrene, an approximately equimolecular mixture, it was observed that the initially formed copolymer contained about 80 per cent of styrene. As the reaction was continued to maximum conversion, the styrene content decreased to approximately 60 per cent. These results show that at this monomer ratio styrene enters the copolymer faster than does isoprene. This behavior is similar to that of styrene when copolymerized with acrylonitrile and with vinylidene chloride. The evidence indicates also that the copolymer is not homogeneous with respect to composition.
Emulsion Polymerization of Diene Hydrocarbons
Authors: Starkweather H. W. , Bare P. O. , Carter A. S. , Hill F. B. , Hurka V. R. , Mighton C. J. , Sanders P. A. , Walker H. W. , Youker M. A. 
Published: February 2011

Abstract
In any study of polymerization, careful consideration must be given to factors such as type and concentration of emulsifying agent, concentration of monomer, temperature, catalyst, and certain added chemicals which may have a marked effect on the results obtained. It is possible to make elastomers of considerable utility from mixtures of butadiene and many other polymerizable compounds. Several of these are superior to those made from butadiene and styrene in particular respects; but considering availability and cost of raw materials, this work has not uncovered any butadiene copolymers which would have been preferred over those made with styrene or acrylonitrile in the period of national emergency. The possibility of obtaining high grade elastomers from the diene hydrocarbons alone appears to justify further investigation.
Absorption of Oxygen by Rubbers
Authors: Carpenter A. S. 
Published: February 2011

Abstract
Constant-pressure oxidation experiments on natural rubber in the absence of antioxidant confirm that the reaction is autocatalytic and essentially similar to that for the oxidation of simple, unconjugated olefins. The results are in accord with a free-radical chain reaction mechanism. In the presence of antioxidant at constant pressure, rubbers reach a dynamic equilibrium state of oxidation at a constant rate. This rate is greater, the greater the pressure, but increases less rapidly than pressure. Several graphs are given to show the relation between equilibrium oxidation rate and oxygen pressure for several rubbers. If the pressure is reduced and again maintained constant after the attainment of the equilibrium oxidation rate at one pressure, the rate at the new pressure falls slowly over several hours from an initial high value to that consistent with the new pressure. This effect is more marked the less susceptible the rubber to oxidation. Methods of investigating the rubber-oxygen reaction in which pressure is allowed to fall spontaneously as oxidation proceeds are experimentally shown to lead to erroneous conclusions. The reasons suggested for this are the auto-catalytic nature of the reaction in the absence of antioxidants and the persistence of a high oxidation rate after a pressure reduction in the presence of anti-oxidant. An approximate relation is deduced between uniformity of oxidation, oxidizability, and specimen dimension for rubbers containing antioxidant.
Oxidation of GR-S and Other Elastomers
Authors: Cole John O. , Field James E. 
Published: February 2011

Abstract
The effect of heat aging on the physical properties of an elastomer is generally considered the result of oxidation, which produces both chain scission and cross-linking in the polymer. Early in the development of GR-S, a marked difference in the aging of GR-S and natural rubber vulcanizates was observed. From the effect of aging on hardness, tensile strength, modulus, and elongation it appeared that cross-linking occurred more rapidly than chain scission with GR-S, but the reverse was true with natural rubber. The work reported here was undertaken to provide a better understanding of the differences in aging of GR-S and natural rubber and to introduce new experimental methods for studying the mechanism of oxidation and antioxidant action in elastomers.
The Possibility of Transforming Rubber into an Ion Exchanger
Authors: Austerweil G. 
Published: February 2011

Abstract
Before taking up the actual subject of the present work, it is well to point out what is meant by an exchange of ions and to define an ion exchanger. An exchange of ions is a chemical reaction which takes place in a heterogeneous medium; when a solid heteropolar substance is immersed in a liquid, usually aqueous, ions belonging to the solid pass into the liquid in exchange for ions of the same polarity in solution in the liquid, and these dissolved ions thereby become fixed on the solid substance in place of the ions which the latter has just given up. As an example, minerals of the type of zeolite (green sand, harmatome, chabasie, etc.) can exchange their alkaline-earth metal ions, i.e., their cations, for sodium ions in an aqueous solution of sea salt which wets them or penetrates through them, and this phenomenon is reversible. Such a reaction is the basis of the detartarizing purification of industrial waters containing lime. Likewise the heteropolarity of exchangers sometimes renders their anions mobile, i.e., some substances give up their anions to liquids which wet them in exhange for the anions of these liquids, which thereby replace the anions liberated from the solids.
Alkylphenol Sulfides as Vulcanizing Agents
Authors: Wolf G. M. , Deger T. E. , Cramer H. I. , DeHilster C. C. 
Published: February 2011

Abstract
An approach to the problem of improving the property of tackiness of butadiene copolymers and a new class of vulcanizing agents for these polymers are discussed. The tack-producing qualities of a number of the alkylphenol sulfides were investigated with respect to their molecular structure and sulfur-content. The precise adjustment of the state of vulcanization is fundamental to the problem of improving the quality of vulcanizates of the butadiene copolymers. The principal approach to the realization of this adjustment previously has been by means of acceleration. It has since been found that the choice of the proper type of vulcanizing agent offers an equally promising approach whereby improvements in quality of the product may be achieved.
Development of a Better Processing GR-S
Authors: Schoene D. L. , Green A. J. , Burns E. R. , Vila G. R. 
Published: February 2011

Abstract
Poor prbcessability has long been recognized as one of the shortcomings of GR-S. Since the problem is of major importance, this deficiency has been the subject of a number of investigations. Freshly milled samples of GR-S shrink rapidly and become very rough. Samples extruded through a die swell excessively and give irregular and broken edges. These faults have, in many instances, necessitated excessive loading with compounding materials to permit satisfactory calendering and extrusion. Sacrifices in quality have often been tolerated to obtain suitable processing. The present paper describes a new type of GR-S in which vastly improved processing properties have been imparted to the polymer during the copolymerization reaction.
Thiuram Disulfides in Compounding
Authors: Morrison G. D. , Shepherd T. 
Published: February 2011

Abstract
Perhaps the chief drawback to the greater employment of thiuram disulfides has been the fear, often groundless, of scorching during processing, and for this reason the work detailed in this paper is devoted entirely to this aspect of their use. The scorching tendency, taken as the commencement of cure, and the rate of vulcanization were studied by means of a modified Goodrich type of plastometer, and the results are expressed as the percentage recovery against time in minutes at 120° C. This temperature (equivalent to 15 lbs. per sq. in. steam pressure) was chosen as being the highest likely to be reached in normal mixing, calendering and extrusion. The rubber compounds tested were prepared from one large batch of base stock comprising: smoked sheet rubber, 100 parts; zinc oxide, 5 parts; and stearic acid, 2 parts. After mixing, the stock was divided into the required number of portions and to these were added the various ingredients detailed later; in all cases the same milling time and temperatures were adhered to so that results would be comparable, especially plasticity. An interval of 24 hours at room temperature was allowed in each case before cutting plastometer test-pieces to dissipate strains imposed in the stock during mixing and sheeting. The test-pieces were then placed in an oven at 120° C, and percentage recovery determinations were made at 5-minute intervals over a range of 5 to 60 minutes.