bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Action of Copper and its Derivatives on the Aging of Rubber
Authors: Villain Henri 
Published: February 2011

Abstract
Most copper compounds increase the rate of autoxidation of rubber mixtures, i.e., they are proöxygenic agents and acclerate aging to a dangerous extent. However, copper may occur in a disguised form and have no deleterious action at all. Moreover, the effects vary considerably, even with the same copper compound, according to the composition of the rubber mixture. Thus certain ingredients, notably, tetramethylthiuram disulfide, neutralize the deleterious action of copper, whereas fat acids increase it. Nevertheless, the presence of a fat acid is not indispensable to the process of degradation brought about by copper, as is evident from tests with rubber mixtures in which the natural fat acids were previously removed from the rubber. From the practical viewpoint, protection against copper can be accomplished effectively by means of certain products such as Agerite White, BLE Powder, and disalycylalethylenediamine, all of which are excellent anticopper agents.
Tear Resistance of Vulcanized Rubber
Authors: Nijveld H. A. W. 
Published: February 2011

Abstract
The method now used at the Rubber Research Institute T.N.O. for determining the tear resistance of vulcanized rubber is described in detail. The tearing test has been studied further. The influence of the thickness of the sample on the tear resistance has been investigated, and some experiments carried out to explain this influence are described. Further experiments indicate that, at the moment of tearing, an elongation is reached locally which is practically equal to the elongation at break of a standard tensile test. Comparison of the angle tear test with the above method leads to the conclusion that the Delft method is to be preferred.
Kinetic Study of the Oxidation of Rubber I.—Some Observations in the Case of Raw Rubber
Authors: Le Bras J. , Salvetti A. 
Published: February 2011

Abstract
After a summary of the main works on the mechanism of rubber oxidation and the antioxidant effect, the principle of a method for the direct measurement and automatic recording of oxidation rates under constant pressure is given. The oxygen necessary for the reaction is produced inside the apparatus by the electrolysis of a solution of copper sulfate, and the noncondensable gases formed during the oxidation are absorbed by caustic potash and sulfuric acid-pumice. Some results obtained with this apparatus during a systematic study of the oxidation of purified crepe at 80° C are described. The influence of the oxygen pressure of the concentration of rubber, of the effects resulting from the transformation undergone by purified crepe, and finally of the action of some anti-oxidants, were investigated. Without discussing the theoretical interpretations, various experimental observations can be made. (1) Even when using ordinary methods of conservation in high vacuum, the samples of rubber undergo modifications which alter its characteristics of oxidation; it is, therefore, necessary always to make simultaneous comparative measurements with a blank. (2) The general shape of the rate of oxidation-time curves indicates the existence of a very strong maximum corresponding closely to the same amount of absorbed oxygen. (3) Variations of the oxygen pressure react on the course of the oxidation. (4) Variation of the concentration of rubber (observed on solutions in toluene) shows that the value of the maximum rate of oxidation is inversely proportional to the concentration. (5) Phenyl-μ-naphthylamine has practically no action on the oxidizability of natural crepe, but is a good antioxidant for purified crepe.
Aging of GR-S Vulcanizates. III. Some Effects of Oxygen and Temperature on Aging
Authors: Scott J. R. 
Published: February 2011

Abstract
Experiments at high temperatures (135° to 153° C) show that the fall in tensile strength and elongation and the increase in modulus of GR-S vulcanizates are accelerated by the presence of oxygen. At 70° C an increase of oxygen concentration from 0.2 atm. (air) to 20 atm. likewise promotes both loss of tensile strength and stiffening (increase of modulus), unless the rubber is under-vulcanized, when the increase of oxygen concentration often results in less stiffening. The increase of oxygen concentration also causes the aged rubber to retain more set after stretching. At 80° C, increasing the oxygen concentration from 0.2 to 20 atm. does not promote stiffening even in well vulcanized rubbers, and may even lead to less stiffening. These results indicate the following general conclusions: (1) oxidation, in addition to promoting loss of strength, is one of the causes of the stiffening of GR-S during aging, presumably due to oxygen-bridging between the molecules; (2) oxidation can also cause softening, presumably by chain scission, which further results in a change in the shape of the stress-strain curve and an increased set after deformation; (3) at high temperatures (80° C or above) increase of oxygen concentration, as in the bomb test, favors the softening reaction relative to the stiffening reaction, but at 70° C (and presumably below) this effect is not evident; (4) undervulcanized GR-S is especially susceptible to the softening (chain scission) reaction; (5) the fact that the softening reaction is favored by increase of oxygen concentration at a high temperature casts doubt on the value of a high-temperature oxygen bomb test for simulating the natural aging of GR-S (see Part IV for an analogous conclusion on other accelerated tests). The above conclusions agree with and extend those of Shelton and Winn. Prolonged (60-day) air-aging tests at 100° C confirm a previous suggestion that the tensile strength of GR-S vulcanizates reaches a constant value or even increases eventually; however, they become progressively stiffer and less extensible. Thus, under hot service conditions GR-S is more likely to fail through inability to stretch than through loss of strength.
Aging of GR-S Vulcanizates. IV. Influence of the Vulcanizing Ingredients, Antioxidant, and Softener
Authors: Scott J. R. 
Published: February 2011

Abstract
The results of air aging at temperatures from 25° to 100° C and of oxygen-bomb aging are discussed in relation to the composition of the mix; notes are given also on the relation of composition to the properties before aging. The main conclusions are: (1) a low proportion of sulfur or (still better) vulcanization by tetramethylthiuram disulfide (TMT) improves the maintenance of tensile strength and elongation under all conditions examined; a low-sulfur mix containing selenium gives results intermediate between the normal low-sulfur and TMT-vulcanized mixes; (2) when judged by the stiffening and hardening during aging, the relative merits of these alternative vulcanizing agents are different, age-stiffening being generally least with low sulfur plus selenium and greatest with TMT vulcanization; (3) on the whole, mercapto-benzothiazole (MBT) gave better results than TMT as an accelerator in mixes with the same proportion of sulfur; (4) acetone extraction of raw GR-S did not lead to the bad aging expected from the removal of antioxidant, but this point needs further study in view of contrary conclusions by other workers; (5) a large proportion of softener somewhat improves maintenance of strength but increases age-stiffening; (6) in general the formulation giving the best maintenance of tension strength and elongation does not give the least age-stiffening, and vice-versa; for the former, TMT vulcanization (possibly plus softener) appears best; for the latter an MBT-accelerated low-sulfur mix, possibly plus selenium, and (7) the 100° C air and the oxygen-bomb aging tests may give misleading indications of aging behavior in air at lower temperatures.
Some Observations on the Oxidation of Rubber in Light
Authors: Stafford R. L. 
Published: February 2011

Abstract
An apparatus is described for measuring the oxygen absorption of vulcanized rubber, either in darkness or under illumination from a controlled light source. The light and dark oxidation curves of four vulcanizates at temperatures of 60°, 65°, and 70° C are examined. Three of the four vulcanizates were protected by the incorporation, respectively, of 2 per cent phenyl-β-naphthylamine, 2 per cent mercaptobenzimidazole, and a mixture of 1 per cent each of the above substances. The dark reaction over 60 hours' duration was in all cases similar and could be represented by a standard equation. It is shown that the effects of PBN and MBI on the dark oxidation are clearly different throughout the temperature ranges. From a consideration of the initial reaction, the decay during storage of the initial oxidizability of the vulcanizates is shown. In oxidation under light from a relatively weak source at a given temperature, the total absorption is considered as the sum of the dark thermal oxidation appropriate to the temperature, and a light-activated absorption. The effect of the light is then shown to be similar in all cases, the rate of absorption due to light starting from zero and increasing through a maximum to a constant value. By comparison of these constant light rates, it is shown that PBN and MBI have little effect on the light-activated absorption of the control, but that the mixture (PBN, MBI) effectively reduces this absorption. The persistence or development of an enhanced dark rate after illumination is shown to depend on the period of illumination and the length of dark storage of the vulcanizate.
Interaction between Polymers and Fillers
Authors: Houwink R. 
Published: February 2011

Abstract
In the literature the problem of whether or not filler particles adhere to a polymer is still under discussion. This point is already of interest in the mixing process because here the question resolves itself into whether the particles clog together or each becomes separately surrounded by polymer only. The problem is also of paramount interest with regard to the properties of the final mixture because upon the interaction depends whether or not a filler has a reinforcing action. This is a key problem, especially in the rubber industry. Essentially, the problem of dispersing a filler in a polymer is of the same type as that of dissolving a polymer in a solvent, and for the thermodynamic considerations we know that dispersing occurs if (leaving the entropy factor out of discussion) ΔU(U=internal energy) is negative, that is, heat is liberated. Here the historical measurements of Hock and his coworkers show that, on mixing rubber with carbon black, 11 gcal. per gram of black (which is of the order of 1 gcal. per mole) extrapolated to zero concentration, are developed. This heat is found to decrease with increasing proportion of filler, showing that all particles are no longer in contact with the rubber because of clogging. It has long been a problem to explain the outstanding reinforcing properties of carbon black with the aid of these low values found by Hock. Smith and Schaeffer showed that the initial heat of adsorption between carbon black and C4 hydrocarbons is of the order of magnitude of 15 kcal. per mole, decreasing sharply until about 40 per cent of a monolayer is formed. This indicates that 40 per cent of the carbon black surface is covered with sites of high adsorptive capacity. Between 40 and 100 per cent of this monolayer formation the surface appears to be quite uniform with regard to adsorptive capacity; at the monolayer the values again decrease and approach the heat of liquefaction, EL, of the adsorbate. These results are shown in Figure 1. From the data obtained, it can be derived that the heat of adsorption per CH2 group to carbon black is about 4 kcal./mole.
Mechanism of Reënforcement. IV. Adsorption of GR-S by Carbon Black
Authors: Amborski Leonard E. , Black Carl E. , Goldfinger George 
Published: February 2011

Abstract
Infrared absorption analysis has been carried out to determine whether the adsorption of GR-S (co-polymer of polystyrene and polybutadiene) on carbon black is specific as to the chemical structure of the polymer. The comparison of the relative intensities of the characteristic absorption bands of the original GR-S with the ratios of the intensities of the same bands for the fraction of rubber remaining after certain fractions were specifically removed by carbon black has shown that the adsorption is not specific as to chemical structure within the limits of accuracy of infrared analysis. The particular chemical groups considered were the phenyl structure (infrared absorption at 13.20 and 14.27 microns) of polystyrene and the 1,2 (10.08 and 10.95 microns) and 1,4 (10.37 microns) addition units of butadiene.
Oxygen Absorption of Vulcanizates. A Means of Evaluating Aging Resistance
Authors: Pollack Louis R. , McElwain Robert E. , Wagner Paul T. 
Published: February 2011

Abstract
The rates of oxygen absorption of two natural and six synthetic-rubber stocks have been measured. In addition, the course of aging in the oxygen bomb and air oven was followed by means of changes in tensile strength and in ultimate elongation of the same eight stocks. Correlation between rates of oxygen absorption and deterioration of physical properties is close enough to justify substitution of a rapid oxygen absorption measurement for longer standard procedures in evaluating the aging characteristics of rubber stocks.
The Preparation and Properties of Highly Purified Rubber
Authors: Martin G. 
Published: February 2011

Abstract
A method is described for obtaining highly purified Hevea rubber, 99.9 per cent pure hydrocarbon, by addition of soap to ammonia-preserved latex to displace the protein from the rubber particle surfaces, followed by repeated creaming, solubilization in hexane, centrifuging, precipitation, and extraction with acetone. Prevention or limitation of oxidation of the pure hydrocarbon was obtained by work in darkness, or by treatment of the latex with pyrogallol and extraction with pyrogallol in acetone. Results are given on the vulcanization behavior of highly purified rubber, showing marked improvement in resilience, while there are remarkable differences in the mechanical properties of vulcaniz zates from sol and gel fractions in some mixes.
Kinetic Analysis of Rubber Halides
Authors: Salomon G. , Koningsberger C. , Ultée A. J. 
Published: February 2011

Abstract
A correlation is established between the structure of an organic halide and its rate of reaction with a number of organic bases. Analysis by reaction kinetics, based on this correlation, is applied to the following problems. (1) Estimation of the allylic fraction in the chlorination and bromination of natural rubber. (2) Differentiation between a dichloride and a polychloride from natural rubber. (3) Determination of an equilibrium between natural rubber and hydrochloric acid at 130° C in closed systems. (4) Identification of tertiary chlorides and bromides in natural rubber and allied polymers.
Reaction of Bromine with Rubber in Aqueous Suspension and Its Analytical Use
Authors: Maffei Francisco J. , Outa M. 
Published: February 2011

Abstract
The rubber hydrocarbon is considered to consist of the combination of an indeterminate number of C5H8 or isoprene units. In this unit there is a double bond capable of adding two atoms of bromine. This addition takes place with pairs of C5H8 groups, with formation of the tetrabromide C10Hl6Br4. Under certain conditions the compound C10H15Br5 is formed, in which case bromine replaces one atom of hydrogen and, at the same time, hydrogen bromide is liberated. The direct determination of the hydrocarbon of rubber by its transformation into the tetrabromide has been utilized by various investigators. Rubber dissolved in benzene, chloroform, or carbon tetrachloride is treated with a solution of free bromine and carbon tetrachloride. The tetrabromide which is formed is separated and weighed. The volumetric determination of the rubber hydrocarbon by bromine is generally impaired by the action of the bromine on the solvent and on the impurities which are present in the rubber. We have tried to study in this work the combination of bromine with rubber in aqueous dispersion, particularly in latex, by an indirect method, based on accepted definitions of the dry rubber content and the total dry residue. The bromine is used in the form of a mixture of bromate and bromide in the presence of acid, and the excess is determined volumetrically. In this way, a bromination factor is obtained, which represents the quantity of bromine consumed per unit of rubber.
Adhesion of Rubber and Textiles. I. Preliminary Evaluation of Synthetic Rubbers in Rubber to Fabric Adhesion
Authors: Hammond G. L. , Moakes R. C. W. 
Published: February 2011

Abstract
In the bonding of two fabric layers by means of a polymer film, it seems that there are two factors, (1) the adhesion of the fabric to the polymer film, and (2) the inherent cohesion of the film itself. With polymers in which cohesion is normally poorer than adhesion for nonvulcanizing films, e.g., GR-S, stripping under most conditions is of the cohesive type; the stripping load can be increased, in the case of GR-S only, by certain resins with the stripping remaining of the cohesive type. When such polymers are used in vulcanizing cements, stripping becomes of the adhesive type, due presumably to the improved cohesion of the polymer by cross-linking. Further, adhesion appears to be at a maximum for lightly vulcanized films, and gets progressively poorer with further curing. The importance of control of film thickness in the quantitative evaluation of rubber cements is demonstrated, and a fairly broad picture of the behavior of GR-S in rubber cements is given. It seems that bond strength between two layers of fabric of the same order as with natural rubber can be obtained with GR-S with the addition of suitable resins. The big drawback to its commercial use in cements seems to be the fact that to obtain good bonds it is essential for doubling to be carried out while a fair amount of solvent is still present.
Adhesion of Rubber and Textiles. II. Factors Influencing the Load Required to Strip Rubber from Fabric and Foil Surfaces
Authors: Borroff E. M. , Wake W. C. 
Published: February 2011

Abstract
By means of experiments with chemically treated fabrics in which the mechanical factor is left unchanged and other experiments with foil materials, the part played by specific factors in rubber to fabric adhesion is shown to be relatively unimportant. Specific factors do exist, and their magnitude is connected with the existence of polar groups or groups that can be polarized. The adhesion secured by the use of spun staple fiber effectively outweighs all other factors.
Adhesion of Rubber and Textiles. III. Examination of Test Technique
Authors: Borroff E. M. , Wake W. C. 
Published: February 2011

Abstract
The variation with the rate of stripping of the load required to break rubber-to-fabric bonds is discussed for unvulcanized and vulcanized rubbers, and this is followed by a discussion of the load variation with period of vulcanization. The two features which are evident in stripping tests are separated, and a simple direct tension test is proposed as a more reliable measure of adhesion. An improved stripping test is proposed and this, together with the direct tension test, is discussed in a final section on the relation between the two tests and their application to practical problems.
Adhesion of Rubber and Textiles. IV. Function of Staple Fiber in Rubber to Fabric Adhesion
Authors: Borroff E. M. , Wake W. C. 
Published: February 2011

Abstract
An investigation of the adhesion of rubbers to a series of fabrics woven from spun staple and continuous filament viscose, acetate rayon, and nylon is described. Using the direct tension test, it is shown that adhesion strength is a property of the staple fiber and is directly related to its tensile strength. The number of projecting fibers has been determined and compared with the broken-off ends recovered from a natural rubber cement after stripping from the fabric. The size-distribution histograms of the recovered fiber ends are also given and discussed. Recommendations are made for utilizing the results so far obtained in this investigation for the production of improved rubber-textile articles.
Staining Problems Associated with Rubber Chemicals
Authors: Haworth James , Pryer W. R. 
Published: February 2011

Abstract
This paper describes a program of systematic work carried out on staining phenomena associated with vulcanized rubber. It is realized that information on the subject must inevitably exist within the industry, but it is thought that it consists largely of isolated facts. An attempt has, therefore, been made to gather together the parts so as to present the picture as a whole and at the same time to explore various practical applications where staining is of paramount importance.
Mastication and Compounding of Natural Rubber in an Oxygen-Free Atmosphere
Authors: Blow C. M. , Wood R. I. 
Published: February 2011

Abstract
Confirmation has been obtained that raw rubber when masticated in the absence of oxygen undergoes only a limited amount of breakdown; and it has been shown that two of the better known socalled “peptizers” or chemical plasticizers of rubber, viz., mercaptobenzothiazole and o-o′-dibenzamidodiphenyl disulfide, require oxygen to be effective. A range of pure-gum rubbers has been compounded under nitrogen, and the physical properties after vulcanization compared with corresponding air-compounded rubbers. Some types of acceleration give vulcanizates whose physical properties are very sensitive to changes in the viscosity of the unvulcanized stock, decrease in viscosity giving decreased modulus. Other types of acceleration, notably “boosted” combinations which give high modulus vulcanization, are insensitive to stock viscosity changes over a wide range. This work forms part of a program of research undertaken by the Board of the British Rubber Producers' Research Association.