bluuebunny/crossref_metadata_2025 huggingface dataset:
Du communisme national au national-communisme
Authors: Gridan Irina
Published: February 2011

Résumé Cet article analyse le retour en force du national dans la Roumanie des années 1960 comme une réaction à la soviétisation. Les dirigeants roumains exploitent alors habilement les sentiments russophobes de la population, dans le cadre d’une stratégie de légitimation interne et externe. Politique nationale de développement économique dans un premier temps, le communisme national évolue au milieu de la décennie vers un nationalisme d’État, à la fois politique et culturel, maniant une rhétorique ouvertement antisoviétique et tendant vers une définition de la nation en termes ethniques. L’analyse de cette maturation du national-communisme permet de voir que le cas roumain n’est nullement une exception à l’échelle du bloc soviétique. Par ailleurs, l’étude souligne que le ferment nationaliste de la politique menée dans les années 1960 par Gheorghe Gheorghiu-Dej puis Nicolae Ceauşescu n’est pas radicalement innovant ; il mobilise au contraire des processus de construction identitaire et des éléments fédérateurs déjà expérimentés par le nationalisme roumain du 19e siècle, puis celui de l’entre-deux-guerres.
Transnationalisme social-démocrate et dissidents de l'Est pendant la guerre froide
Authors: Boel Bent
Published: February 2011

Résumé La dissidence dans les pays de l’Est confronta les partis sociaux-démocrates occidentaux à un dilemme : comment manifester sa solidarité avec les opprimés de l’Est tout en œuvrant pour la Détente entre les deux blocs ? Alors que certains observateurs soulignent l’indifférence social-démocrate, d’autres pensent pouvoir identifier une « double stratégie », les dirigeants focalisant sur les rapports avec les gouvernements, les niveaux plus subalternes s’occupant des relations avec les dissidents. S’il est clair qu’une approche « réaliste » des relations internationales a poussé les sociaux-démocrates à donner la priorité aux relations avec les régimes communistes, il n’y en eut pas moins des efforts de la part de certains pour entretenir des relations avec les dissidents. Cela vaut aussi bien par rapport aux exilés de l’Est, que pour les oppositionnels en Pologne, en Tchécoslovaquie ou en RDA.
Les jeunes, l'Ouest et la police secrète tchécoslovaque
Authors: Huguenin Duane
Published: February 2011

Résumé À la fin des années 1950, à l’instar de l’ensemble des pays européens, le régime communiste tchécoslovaque se trouve confronté à une occidentalisation croissante de la jeunesse du pays, notamment sous l’influence de la culture américaine. Ce phénomène inquiète suffisamment le parti communiste pour que la police secrète, la StB, soit mobilisée. Elle a pour mission de lutter contre cette « diversion idéologique » qui risque de ruiner les espoirs que le régime place dans la jeune génération. Néanmoins, ceci ne se traduit pas par une utilisation massive de la répression. Au contraire, dans son action envers les jeunes, la police secrète tchécoslovaque est constamment tiraillée entre deux impératifs : protéger une jeunesse vue comme vulnérable et lutter contre une influence occidentale considérée comme criminelle. Cette ambivalence de l’action policière persiste tout au long des années 1960 et empêche le régime communiste de saisir la portée de l’agitation qui règne alors parmi les jeunes.
Penicillium marneffeiInfection in AIDS
Authors: Wong Stephenie Y. N. , Wong K. F.
Published: February 2011

Penicillium marneffeiis a dimorphic fungus which is endemic in Southeast Asia. It is an opportunistic pathogen which has emerged to become an AIDS-defining illness in the endemic areas. Early diagnosis with prompt initiation of treatment is crucial for its management. Prompt diagnosis can often be established through careful cytological and histological examination of clinical specimens although microbiological culture remains the gold standard for its diagnosis. Standard antifungal treatment for AIDS patients with penicilliosis is well established. Highly active antiretroviral therapy should be started early together with the antifungal treatment. Special attention should be paid to potential drug interaction between antiretroviral and antifungal treatments. Secondary prophylaxis may be discontinued with a low risk of relapse of the infection once the immune dysfunction has improved.
Measurements of gaseous H2SO4 by AP-ID-CIMS during CAREBeijing 2008 Campaign
Authors: Zheng J. , Hu M. , Zhang R. , Yue D. , Wang Z. , Guo S. , Li X. , Bohn B. , Shao M. , He L. , Huang X. , Wiedensohler A. , Zhu T.
Published: February 2011

Abstract. As part of the 2008 Campaign of Air Quality Research in Beijing and Surrounding Regions (CAREBeijing 2008), measurements of gaseous sulfuric acid (H2SO4) have been conducted at an urban site in Beijing, China from 7 July to 25 September 2008 using atmospheric pressure ion drift – chemical ionization mass spectrometry (AP-ID-CIMS). This represents the first gaseous H2SO4 measurements in China. Diurnal profile of sulfuric acid is strongly dependent on the actinic flux, reaching a daily maximum around noontime and with an hourly average concentration of 5 × 106 molecule cm−3. Simulation of sulfuric acid on the basis of the measured sulfur dioxide concentration, photolysis rates of ozone and nitrogen dioxide, and aerosol surface areas captures the trend of the measured H2SO4 diurnal variation within the uncertainties, indicating that photochemical production and condensation onto preexisting particle surface dominate the observed diurnal H2SO4 profile. The frequency of the peak H2SO4 concentration exceeding 5 × 106 molecule cm−3 increases by 16% during the period of the summer Olympic Games (8–23 August 2008), because of the implementation of air quality control regulations. Using a multivariate statistical method, the critical nucleus during nucleation events is inferred, containing two H2SO4 molecules (R2 = 0.85). When neither nucleation nor precipitation occurs, the condensation rate of H2SO4 correlates with the daytime sulfate mass concentration of the Aitken mode, but not with that of the accumulation mode aerosols.
Detection and phylogenetic analysis of coastal bioaerosols using culture dependent and independent techniques
Authors: Urbano R. , Palenik B. , Gaston C.  J. , Prather K. A.
Published: February 2011

Abstract. Bioaerosols are emerging as important yet poorly understood players in atmospheric processes. Microorganisms can impact atmospheric chemistry through metabolic reactions and can potentially influence physical processes by participating in ice nucleation and cloud droplet formation. Microbial roles in atmospheric processes are thought to be species-specific and potentially dependent on cell viability. Using a coastal pier monitoring site as a sampling platform, culture-dependent (i.e. agar plates) and culture-independent (i.e. DNA clone libraries from filters) approaches were combined with 18S rRNA and 16S rRNA gene targeting to obtain insight into the local atmospheric microbial composition. From 13 microbial isolates and 42 DNA library clones, a total of 55 sequences were obtained representing four independent sampling events. Sequence analysis revealed that in these coastal samples two fungal phyla, Ascomycota and Basidiomycota, predominate among eukaryotes while Firmicutes and Proteobacteria predominate among bacteria. Furthermore, our culture-dependent study verifies the viability of microbes from all four phyla detected through our culture-independent study. Contrary to our expectations and despite oceanic air mass sources, common marine planktonic bacteria and phytoplankton were not typically found. The abundance of terrestrial and marine sediment-associated microorganisms suggests a potential importance for bioaerosols derived from beaches and/or coastal erosion processes.
Reconstructing and analyzing China's fifty-nine year (1951–2009) drought history using hydrological model simulation
Authors: Wu Z. Y. , Lu G. H. , Wen L. , Lin C. A.
Published: February 2011

Abstract. The recent fifty-nine year (1951–2009) drought history of China is reconstructed using daily soil moisture values generated by the Variable Infiltration Capacity (VIC) land surface macroscale hydrology model. VIC is applied over a grid of 10 458 points with a spatial resolution of 30 km × 30 km, and is driven by observed daily maximum and minimum air temperature and precipitation from 624 long-term meteorological stations. The VIC soil moisture is used to calculate the Soil Moisture Anomaly Percentage Index (SMAPI), which can be used as a measure of the severity of agricultural drought on a global basis. We develop a SMAPI-based drought identification procedure for practical uses in the identification of both grid point and regional drought events. As the result, a total of 325 regional drought events varying in time and strength are identified from China's nine drought study regions. These drought events can thus be assessed quantitatively at different spatial and temporal scales. The result shows that the severe drought events of 1978, 2000 and 2006 are well reconstructed, indicating SMAPI is capable of indentifying the onset of a drought event, its progressing, as well as its ending. Spatial and temporal variations of droughts on China's nine drought study regions are studied. Our result shows that on average, up to 30% of the total area of China is prone to drought. Regionally, an upward trend in drought-affected areas has been detected in three regions Inner Mongolia, Northeast and North during the recent fifty-nine years. However, the decadal variability of droughts has been week in the rest five regions South, Southwest, East, Northwest, and Tibet. Xinjiang has even been wetting steadily since the 1950s. Two regional dry centers are discovered in China as the result of a combined analysis on the occurrence of drought events from both grid points and drought study regions. The first center is located in the area partially covered by two drought study regions North and Northwest, which extends to the southeastern portion of Inner Mongolia and the southwest part of Northeast. The second one is found in the central to southern portion of the drought study region South. Our study demonstrates the applicability and the value of using modeled soil moisture for reconstructing drought histories, and SMAPI is useful to analyzing drought at different spatial and temporal scales.
Effect of Vulcanization on Rubber Structure. A Problem in Probabilities
Authors: Busse Warren F.
Published: February 2011

In Goodyear's day, the problem of understanding the process of vulcanization could be expressed by the question: “Why does heating rubber with sulfur keep it from getting soft and tacky on a hot summer day, and hard and boardy in cold winter weather?” The deceptive simplicity of this question probably inspired the hope, which has come down almost to the present day, that the secrets of vulcanization and even of the elasticity of rubber could be explained in terms of the properties and reactions of simple organic molecules, such as the reactions of sulfur with simple olefins. The vast increase in the knowledge of giant molecules during the past decade has shattered any basis there may have been for such a hope, but occasional articles show that this desire for simplicity continues to live and to color our thinking on this problem. This paper discusses some of the inherent limitations of the old, simpler pictures of vulcanization and the structure of rubber, and some of the implications of the present view that crude rubber is built up of giant molecules. Probably there are not merely one or two or half a dozen reactions, but rather there are literally millions of possible vulcanization reactions, each of which may influence the physical properties of the rubber. The study of these reactions will require new and far more sensitive methods of physical and chemical analysis than have been available heretofore, as well as new points of view in interpreting the data.
Effect of Rubber Variability on Vulcanization
Authors: Hastings J. D. , Rhodes Edgar
Published: February 2011

It is hoped that the results given will have indicated that the effect of variation on vulcanizing properties is well recognized by the producers and that they are not apathetic towards the consumers' requirements. Variability, however, is a problem which does not appear to have an immediate solution because it seems to be caused, for the most part, by inherent variations in latex; these variations are the result of differences in the trees themselves, in the soil and other environmental conditions under which they are growing, or in the methods used on the estate. Such differences are either outside of human control or are a necessary consequence of economic conditions. The conclusion expressed by Sackett that the consumer must bear the burden of eliminating most of the variation by blending is unfortunately still a true statement of the position.
Tensile Properties of Rubber Compounds at High Rates of Stretch
Authors: Roth Frank L. , Holt William L.
Published: February 2011

Stress-strain relationships and the work of extension for four rubber compounds were studied for a rate of stretching of the order of 1,000 per cent per second. This rate is sufficiently great so that the test may be considered to approach adiabatic conditions. A comparison of these data with similar data for a rate of stretching which lies in the range of speeds common to the usual routine tests shows that increased speed of stretching affects the observed tensile properties as follows: (1) the stresses' are increased at elongations up to about 500 per cent for the loaded compounds and up to 600 per cent for the pure-gum compound, the maximum increases ranging from 75 pounds per square inch for the pure-gum compound to 245 pounds per square inch for the clay compound; (2) the stresses in the carbon-black compounds are decreased slightly at elongations near rupture; (3) the work of extension to rupture is increased for the pure-gum and clay compounds and decreased for the carbon-black compounds, and (4) the work of extension for a given elongation is increased for all the compounds. The stresses and the work of extension at the higher speed reveal no information indicative of resistance to abrasive wear that cannot be gained from similar studies of data obtained in stretching the specimen slowly.
Effect of Petroleum Products on Neoprene Vulcanizates. I. Effect of Lubricating Oils
Authors: Fraser Donald F.
Published: February 2011

The aniline point and the viscosity-gravity constant of petroleum derived oils may be used as criteria of the swelling effect of the oils on Neoprene vulcanizates. One or other of the constants should be used to describe or identify any oil to be used as a testing medium in swelling tests forming part of control or purchase specifications for Neoprene fabricated parts. Such a step will insure comparable results between different laboratories, and will enable samples of oils to be duplicated insofar as their swelling action is concerned. The aniline point and the viscosity-gravity constant are equally reliable, except in the case of high viscosity index hydraulic oils (containing polybutene), where the aniline point is preferred. The dark color of some oils may dictate the use of the viscosity-gravity constant. Other things being equal, the aniline point is preferred because of the ease of determination and lack of specialized apparatus.
Determination of Free Carbon in Rubber. The Cresol Method
Authors: Roberts J. B.
Published: February 2011

A simple, accurate method for the determination of free carbon in either raw or vulcanized rubber is presented. It has replaced the nitric acid method entirely in the laboratory of the United States Rubber Company, Detroit, Michigan. A study of the effects of interfering substances, and numerous comparisons of results by the cresol and the nitric acid methods, are given. Results by the cresol method, in the absence of interfering substances, are within 1 per cent of the calculated free carbon content. The method requires only simple apparatus readily available.
Creaming of Rubber Latex
Authors: Hauser E. A. , Dewey Bradley
Published: February 2011

The creaming of rubber latex was first observed as far back as 1824 when Hancock, working with what was probably Castilloa latex, observed that if this latex is well shaken with three or four times its volume of water and then allowed to stand, a separation into two layers will take place which thus effects a purification of the dispersion. This phenomenon, reported again by Faraday in 1825, is a spontaneous creaming which takes place with latices of large particle size. Latex of Hevea brasiliensis will not cream spontaneously in this manner and, although other methods of inducing creaming, such as the addition of caustic alkali, were previously known, it remained for Traube in 1924 to patent the first method which would prove satisfactory for commercial concentration. Rahn had reported in 1922 that the natural creaming of milk could be greatly accelerated and made more complete if small amounts of gelatin or of similar hydrophilic colloids, such as gum tragacanth, gum arabic, peptone or albumen, were added to the milk before allowing it to stand. Recognizing the similarity between milk and rubber latex, Traube applied this knowledge to the development of the creaming of latex. He found such substances as carrageen moss, Iceland moss, and other vegetable mucilages to be effective in causing separation of the latex dispersion into two layers—the upper one rich in rubber and the lower one, generally termed serum, almost free of rubber.
Formation of Compounding Ingredients in Rubber
Authors: Twiss D. F. , Neale A. E. T. , Hale R. W.
Published: February 2011

In 1923, dealing with compounding ingredients for rubber, one of the authors, with particular reference to compounding rubber with carbon black, commented on the attractiveness of the possibility of producing a compounding ingredient immediately inside the rubber colloid medium, to assure its formation in a state of uniform and intimate distribution with reinforcing effect, and with incidental avoidance of the economic and technical disadvantages attendant on mechanical mixing. Numerous experiments, however, with this aim, have given disappointing results. For instance, all attempts to produce amorphous carbon by means of chemical reaction in a rubber medium have been frustrated, either by the special conditions, so that the expected reaction proceeded in an unexpected and undesired direction, or by the carbon separating outside the rubber medium provided for it. A number of endeavors with the same aim, i.e., the improved compounding of rubber, but based on other possible compounding ingredients, was described in another paper in 1933, in which the ideal conditions for compounding in situ were reviewed. Two of the more important of these conditions were that the compounding ingredient must be formed in the rubber phase and must be as nearly insoluble therein as possible. More recent investigations into the mechanism by which carbon black exercises its beneficial influence on the mechanical qualities of rubber in which it is dispersed admittedly indicate that mere dispersion of ultrafine particles in the rubber phase may not be the only important factor. At present, however, such dispersion of fine particles appears to be an essential first step in the compounding process for eventual reinforcement, so that compounding by formation of reinforcing agents in situ may still provide a valuable or even essential step in methods for the production of rubber with exceptionally enhanced physical or mechanical characteristics.
Experiments on the Degradation of Buna-S. Part I
Authors: Reiner St.
Published: February 2011

In this first communication on the subject, an apparatus is described, with the aid of which experiments on the degradation of Buna S and Buna SS can be carried out on a laboratory scale. The experiments thus far completed show that the volume of air, at least above the range of very low quantities, has no marked influence on the degree to which Buna is degraded under otherwise constant conditions. Likewise the viscosities are hardly influenced by a change in the rate of flow of air. Only the elastic components increase with reduction in the volume of air supplied to the sample. With slightly degraded Buna (see Table 2), the effect of low rates of flow of air can be observed clearly. From a practical point of view, the experiments show that a minimum quantity of air, i. e., a definite rate of flow, is necessary for degrading Buna-S. On the basis of the experiments described, a minimum of approximately 20 liters of air per hour may be assumed to be necessary to degrade 50 grams of Buna-S in crumb form. Converted to a large-scale basis, this would mean that at least 40 cubic meters of air per hour would be necessary to degrade 100 kilograms of Buna-S in uniform crumb form, provided the air is distributed uniformly throughout the reaction vessel. Electric drying chambers and vulcanizers which have no continuous supply, but only a stationary volume of air, are not suitable, since the quantity of air is far from sufficient to bring about homogeneous degradation. Most factories which use Buna have suitable equipment with a supply of air under pressure, so that the volume of oxygen necessary for degradation can be supplied to the Buna.
Rubber in the Automotive Industry. From the Viewpoint of the Rubber Technologist
Authors: Cadwell S. M. , Merrill R. A. , Sloman C. M. , Yost F. L.
Published: February 2011

About 80 per cent of the rubber consumed in the United States is used in the automotive industry. Rubber was necessary for the development of the modern automobile, and the popularity of the automobile has, in turn, tremendously enlarged the rubber business. The parallel growth of the rubber and automotive industries is apparent in Figure 1, where the consumption of rubber is compared with the registration of motor vehicles in the United States for the past thirty years. The modern automobile contains about two hundred different parts made wholly or in considerable part of rubber. Including the tires and tubes, the weight of these materials is about 145 pounds per car. Rubber is used in the automobile in practically all of its available forms, either as latex, cements, soft rubber, hard rubber, or sponge rubber. Every important characteristic of rubber is utilized. Rubber has a wider range of properties than any other single material and automotive engineers are to be congratulated on their progressiveness in using these unique and valuable properties to improve their product.
Determination of Scorching of Rubber and Synthetic Compounds by Use of the Mooney Plastometer
Authors: Weaver John V.
Published: February 2011

There are in use today several methods for determining the scorching point of rubber and synthetic compounds. Some compounders use the Williams plastometer method, while others press-cure a thin slab of compound for increasing periods of time at 220° F or thereabouts until an examination of the slab shows that vulcanization has taken place. Another method consists of heating several pieces of the compound in an oven and removing at constant intervals until the compound scorches. The test-pieces in the latter method are quite often sheeted out on a mill to determine if any vulcanization has taken place. These methods all give good indications of the scorching point; however, each one is a rather long and tedious test. The Mooney plastometer scorch test cuts down the time considerably and gives a picture of the scorching rate, when the plasticity is plotted against the time. It is necessary, as a rule, to run this test only 10 or 12 minutes at 250° F to determine just how scorchy a compound really is, while the other methods cited sometimes require an hour or more to determine the scorching characteristics. It is desirable also to express the results of any test in the form of a graph or curve, so that one may make comparisons more easily without reviewing a lot of data. The Mooney scorch test gives results which can be plotted in the form of a curve, which also shows some very interesting facts aside from the scorching characteristics. The plasticity of the compound, the point at which vulcanization begins, and the rate of vulcanization after it begins, are shown. Summarizing the advantages of this test in a few words, one can say that it affords a quick, convenient method for determining scorching characteristics, and that it gives a clearer and more informative picture of scorching than other methods used today. Just a few illustrations demonstrating the use of the Mooney plastometer as an instrument for determining scorch have been given in this report. They do, however, point out the value of this test in the following ways: (1) The Mooney scorch test gives a quick method for studying the effect of various accelerators and accelerator combinations on the scorching characteristics of rubber compounds. It can also be used to show the effect of a retarder with various accelerators, and the effect of any other compounding change which might have a bearing on the scorching characteristics. (2) The Mooney scorch test may be used to show the relationship between scorching and rate of curing. As has been pointed out, there appears to be a definite relationship; however, before any general statements can be made, a considerable amount of work would be necessary. In the particular example cited here (Curve Sheet No. 2), one could visualize, from the shape of the Mooney scorch curves, the rate of curing of these compounds from the first signs of vulcanization to the peak cure.
Possibilities of Utilizing the Polarographic Method in Rubber Laboratories. I
Authors: Proske G.
Published: February 2011

Following a brief description of electrochemical principles and the experimental technique of the polarographic method, possible applications of this method in the rubber laboratory are discussed in some detail. In addition to its availability in many ways for the determination and the investigation of numerous inorganic materials which are so frequently analyzed in rubber laboratories, the polarographic method is of special importance in the determination of organic accelerators of vulcanization. The first investigations of the author in this field are described in detail.
Hysteresis in the Crystallization of Stretched Vulcanized Rubber. II. X-Ray Studies of the Effects of Sulfur Content and Method of Curing
Authors: Clark G. L. , LeTourneau R. L. , Ball J. M.
Published: February 2011

1. Improvements in technique make possible complete rubber patterns in only five minutes' exposure. 2. The extreme sensitivity of hysteresis in crystallization to changes in temperature at which the stock is investigated is demonstrated. 3. Hysteresis decreases with the time of cure for a given compound. 4. Crystallinity at a given elongation seems to decrease with increasing temperature of curing for equivalent cures over the range of 239–307° F. 5. For the stock studied, at a given time and temperature of cure, the proportion of sulfur giving the greatest crystallinity at 550 per cent is between one and three per cent. 6. Inhomogeneities in the disappearance of crystallinity have been clearly demonstrated, and shown to be an exaggerated localized hysteresis effect.
An X-Ray Study of the Proportion of Crystalline and Amorphous Components in Stretched Rubber
Authors: Field J. E.
Published: February 2011

A method is described for obtaining a quantitative measure of crystalline hydrocarbon present in stretched rubber samples by comparing the intensities of the diffraction spots and the amorphous halo appearing in the x-ray diagrams. This method has been applied to a study of the crystallinity of stretched vulcanized rubber as it is affected by different vulcanization accelerators, variations in extension, temperature, and cure. To illustrate a connection between the physical performance of a rubber vulcanizate and its degree of crystallization, measurements were made of the relation of crystallinity to creep when the rubber was stretched to different initial elongations under constant loads. The creep as a function of the elongation has a maximum value at the same intermediate elongation for which crystallization becomes appreciable. At higher elongations, increased crystallinity results in a diminution of the creep. The ultimate strength and extensibility generally associated with stretched vulcanized rubber is the result of the combined effect of primary valence cross-linkages formed by vulcanization and the formation of crystallites caused by stretching. Crystallization is an important factor in maintaining the relatively high strengths of vulcanizates having a greater range of extensibilities. In general, the physical properties and performance of vulcanized rubber is related to the amount of crystalline material formed on stretching, which depends on the structural characteristics of the vulcanizate.
Relation between Molecular Weights and Physical Properties of Rubber Fractions
Authors: Gee G. , Treloar L. R. G.
Published: February 2011

As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.
Thermal Problems in Rubber Manufacture
Authors: Hahn Stuart H.
Published: February 2011

The threefold heat problems of the industry are, in order of their occurrence: (1) Controlled removal of heat generated in processing crude rubber. (2) Regulation of heating and cooling processes to give the most nearly uniform vulcanization in the shortest possible time. (3) Measurement and reduction of heat generation in products subject in service to cyclic stress conditions. Each of the three types of problems engages the attention of chemists and engineers as well as physicists. The chemist is constantly searching for new ingredients and combinations of materials which will promote rapid vulcanization at curing temperatures, that is, 240 to 320° F. The same rubber compounds, when unvulcanized, must be relatively insensitive to processing temperatures up to about 220° F; when vulcanized they must withstand prolonged use at temperatures above 200° F. The engineer must design curing equipment and related automatic controls. He also must design the combinations of rubber compounds and structural elements which make up the products of the industry. The physicist must measure and analyze the thermal properties of the raw materials, the rubber compounds and the finished products. He also must apply the methods of the physics laboratory to the study in the factory of thermal problems connected with production operations. The cooperation of all is essential in producing for the consumer better products at lower cost.
The Evaluation of Reclaimed Rubber
Authors: Hublin Roger A.
Published: February 2011

Examples have been given to illustrate a method of evaluation of reclaimed rubbers which takes into account the costs of the materials tested. When correctly applied, this method gives a rapid and, at the same time, precise answer to all questions of cost and quality which may arise in connection with the use of reclaimed rubber. In concluding this discussion, attention should be called to an important point, It has been proved fairly conclusively that, if an effort is made to define in a precise manner any problem to be solved, it is possible to apply rational methods to it. With these methods it is possible to avoid much futile experimentation, and to obtain directly results which are a quite satisfactory approximation to the correct ones. This is true, not only in studying and evaluating reclaimed rubbers, but also of problems in general which arise in connection with compositions and costs of various mixtures. In almost all cases it is possible, by making use of analogous methods of procedure, to save considerable time and effort. It appears to be certain that, thanks to progress in the technique and standardization of testing, it will be possible to make a truly systematic study of rubber compounding.
Hycar-OR. Properties of Typical Compounds
Authors: Garvey B. S. , Juve A. E. , Sauser D. E.
Published: February 2011

Hycar-OR is an oil-resistant synthetic rubber produced and sold by the Hydrocarbon Chemical and Rubber Company, which is jointly owned by The B. F. Goodrich Company and the Phillips Petroleum Company. Articles manufactured from Hycar by The B. F. Goodrich Company are sold under the trade name Ameripol. The object of this paper is to give a general view of the more important properties of a range of Hycar compounds and to illustrate the methods of compounding used. The recipes were selected, not to meet any particular specifications, but to include different types of stocks which might have commercial utility.
Wanted—A New Aging Test
Authors: Stevens W. H.
Published: February 2011

For many years rubber manufactures have been tested by artificial as well as natural aging tests. Of the former, the heat aging test by means of the Geer oven (an electric oven held at 70° C) was the first to be adopted and remains probably, the widest used. The correlation between the Geer oven and natural aging varies according to the type of goods and their conditions of service, but a rough and ready guide is that one day in the oven at 70° C is approximately equivalent to six months of natural life. Other heat-aging tests subject the rubber goods to air or oxygen at elevated temperature and pressure, with proportionate reduction of the time of test necessary for practical results. Apart from heat, light has a great deteriorating effect on rubber and some use has been made of this in testing rubber manufactures which are subject to light aging in service. The purpose of this article is to draw attention to the difficulty of accurately simulating natural light, particularly in reference to the conditions obtaining in direct summer sunlight, which has been found to have a far faster deteriorating action than that of ultraviolet light on rubber. For instance, it has been found that about 10 days of summer sunlight, partly deprived of its ultraviolet fraction by passage through window glass, is sufficient to completely destroy a plain rubber film which will stand up to weeks of light aging by a mercury vapor lamp or of ordinary heat aging at 70° C.
Color Measurements of Latices and of Rubber Films Prepared from Them
Authors: Van Nederveen G.
Published: February 2011

In the introduction to the present work, reasons for latex becoming discolored are reviewed, and the importance of color measurements are discussed. In addition, methods which have been developed for measuring the colors of various socalled white products, such as sugar, flour, paper, and the like, and methods for measuring the color of latex, are reviewed. Some of these methods are subjective; on the contrary, others utilize photocells so that subjective observations are eliminated. Measurements of the colors of different samples of latices were carried out with a Lovibond colorimeter, as a result of which it was found that this instrument is wholly unsuitable for this purpose. Measurements of the colors of both latices and films prepared from these latices were then made with a Hilger blancometer. The method of measuring and of calculating the intensity of the reflected light of a definite color is explained. The results obtained in measurements of the reflection of white light and of blue light from different samples of latex, using a Hilger blancometer, are compared with the results obtained with the same samples of latex estimated by simple visual examination. It was found that latices of good color reflect 80 or more per cent of white light and 78 or more per cent of blue light. The reflection of a yellow latex is considerably less in blue light than in white light. The reflection of a gray latex in white light does not differ much from that in blue light; in each case it is less than 80 per cent. It is proved conclusively that, judged by measurements of the colors of films, there is a close relationship between the color of a latex and the color of white-pigmented films made from the particular latex.
The Polarographic Determination of Organic Accelerators of Vulcanization
Authors: Proske Gerard
Published: February 2011

In spite of the great importance which vulcanization accelerators have attained in the rubber industry, there is still an almost complete lack of analytical methods, both for determining the accelerator contents of rubber mixtures and for identifying accelerators in vulcanized rubber. Apart from the wholly unsatisfactory and uncertain method of deciding the existence of organic accelerators in vulcanized rubber by a Kjeldahl nitrogen determination, there is little of value in the literature. Twiss and Martin have described a few qualitative reactions of accelerators. Recently Shimada described some color reactions of accelerators with cobalt oleate, but the analytical utility of these reactions is very doubtful. Of far more promise than these is the polarographic method, the value of which in the analytical determination of a series of important accelerators was proved in an investigation which will be described in the present paper. It had already been proved in earlier polarographic investigations that organic compounds containing nitrogen with a double bond can be reduced electrolytically, provided groups with a tendency to rupture are close to the double bond. Shikata and Tachi have shown this to be true of azobenzene, and Winkel and Proske of dimethylquinoxaline.
Gasoline Diffusion Resistance of Thiokol Type F
Authors: Martin S. M.
Published: February 2011

The solvent-resistant properties and low swelling characteristics of Thiokol synthetic rubbers are well known to the rubber technologist. It is also known that these rubbers are highly resistant to permeation by solvents. Gasoline and blends of gasoline and benzene do not diffuse into and through them to any great extent. The permeation of rubber and synthetic rubbers by fixed gases, such as hydrogen and helium, has been the subject of considerable study. Such information has a bearing on the construction of dirigibles, blimps, observation balloons, and barrage balloons. Sager shows that the ratio of permeability to hydrogen for Thiokol Type DX (now Type F), compared to rubber at 25° F, is 1 to 12. Recently the diffusion of gasoline and oil through solvent-resisting synthetic rubbers has become of general interest. The information generally sought is the amount of gasoline that diffuses through a given area in a given time.
Rise of Temperature on Fast Stretching of Synthetics and Natural Rubbers
Authors: Dart S. L. , Anthony R. L. , Guth Eugene
Published: February 2011

This investigation covered more types of rubber and rubberlike synthetics than were studied by previous investigators. From the results it seems apparent that at least a part of the disagreement between previous workers on this subject is due to the different types of rubber employed. It is also important to note that the temperature changes observed were of the order predicted by sensory observation.
The Course of Autoöxidation Reactions in Polyisoprenes and Allied Compounds. I. The Structure and Reactive Tendencies of the Peroxides of Simple Olefins
Authors: Farmer Ernest Harold , Sundralingam Alvappillai
Published: February 2011

The structural changes which occur in olefinic substances when they undergo oxidation by molecular oxygen have never been elucidated, although many of these changes, such as the autoöxidation of drying oils and of rubber, are of enormous practical importance.
Processing Characteristics of Synthetic Tire Rubber
Authors: Garvey B. S. , Whitlock M. H. , Freese J. A.
Published: February 2011

The processing characteristics of synthetic tire rubber, such as is being made in the government program, are sufficiently different from those of natural rubber to require different laboratory and factory treatment. Since the laboratory tests used for the evaluation of processing characteristics were developed for natural rubber, it is not surprising that they are not so satisfactory for synthetic rubber. The purpose of this paper is to discuss some of the characteristics of synthetic tire rubber, and to describe certain tests which have been found useful for evaluating different types of synthetic rubber or different compounds of the same synthetic rubber. In the course of the development, it has been necessary to evaluate rubbers with a wide variety of processing properties. As production has increased, there has been less variation in the output from any one plant. As the newer and larger plants come into full production, we can expect greater uniformity from each plant and between different plants. We can also look forward to gradual improvements in processing characteristics. This development will be ensured by adequate laboratory methods for evaluating processing properties. This discussion is based in part on variations encountered in development work and in part on the properties of the present production from one plant.
Density Measurements on Synthetic Rubbers
Authors: Wood Lawrence A. , Bekkedahl Norman , Roth Frank L.
Published: February 2011

For many purposes the density of a material need be known with an accuracy of only a few per cent. For many materials the density of one sample may differ from that of another by this amount, and no useful purpose may be served by making more precise measurements on individual samples. In natural rubber, the densities of different samples have been shown, in a compilation of twenty-one values, to lie with two exceptions between 0.905 and 0.919 gram per cc. at 25° C. The variations probably represent real differences in the samples and not accidental errors of observation. Since one can seldom know exactly the origin and subsequent treatment of a sample of natural rubber, there is little value in increasing the precision of measurement. Synthetic rubbers, on the other hand, can be regarded as usually produced under conditions which are much better controlled and known. It is logical, then, to measure the density with greater precision and to hope to be able to ascribe significance to its variations from one sample to another. The present work is concerned with the development of a method for preparing specimens of synthetic rubber in a form suitable for precise measurements of the density, the actual measurement by the method of hydrostatic weighings, and a presentation of the results for most of the varieties of synthetic rubber now of commercial importance in the United States.
Viscosity and Cryoscopic Data on Polystyrene. Discussion of Staudinger's Viscosity Rule
Authors: Kemp A. R. , Peters H.
Published: February 2011

1. The cryoscopic method is not satisfactory for polystyrenes containing more than twelve styrene units in the chain on account of the failure of their solutions to obey Raoult's law. 2. The present work has established a new Kcm value of 0.45×104 for benzene solutions of polystyrene to be used in the equation: A Kcm value of 0.6×104 has been similarly established for benzene solutions of polyindene. 3. Increased confidence in the viscosity-molecular weight procedure is derived from the data presented for the new Kcm equivalent covering a wide range of different polymers.
The Interaction between Rubber and Liquids. 1. A Thermodynamical Study of the System Rubber-Benzene
Authors: Gee G. , Treloar L. R. G.
Published: February 2011

Equations are developed relating the thermodynamic properties of a mixture of rubber + liquid with the vapor pressure of the liquid above the mixture. Experimental methods are described for the determination of vapor pressure over the whole range of composition of the mixture. By the use of four different methods, it was possible to measure relative vapor pressure lowerings Apo/po° from 2×10−6 to 0.997. Complete vapor pressure data are given for rubber-benzene mixtures at 25° C, together with the calculated Gibbs' free energies of dilution and solution. Temperature coefficient measurements at a number of concentrations are employed to calculate heats of dilution, and these are interpplated by a modified form of an equation due to Langmuir. In this way the heats of dilution and solution are also obtained over the whole range of composition. Combining the heat and free energy data gives the entropies of dilution and solution. The entropy of dilution is approximately twice the heat of dilution over a wide concentration range and, except in dilute solutions (< 5% rubber), both are independent of the molecular weight of the rubber. The entropy of dilution is very much larger than its ideal value, and can be approximately represented by an equation of Flory, though there are significant discrepancies in the region of dilute solutions. The molar heat of solution of rubber is so large that the miscibility of rubber and benzene can be explained only by the anomalously large entropy of solution.
The Bacterial Oxidation of Rubber
Authors: ZoBell Claude E. , Grant Carroll W.
Published: February 2011

In studying the biological oxygen demand of sea water, it has been observed that rubber stoppers increase the amount of oxygen consumed. In fact, the small amount of rubber gasket exposed to the water in citrate of magnesia bottles perceptibly increases the amount of oxygen consumed after 5 to 10 days' incubation. Heat-sterilized as well as formaldehyde-preserved controls proved that the increased oxygen consumption is attributable to biological activity. One-gram samples of various kinds of rubber, cut in small pieces to give a surface area of approximately 10 sq. cm., were placed in 160-cc. glass-stoppered bottles. After sterilizing in an autoclave at 120° C for 20 minutes, the bottles were filled with sterile water saturated with oxygen. Half the bottles were inoculated; the others were left sterile. Duplicate bottles were analyzed for oxygen immediately by the Winkler technique, and the others were incubated in the water bath for one to five days at 22° C, after which the amount of oxygen consumed was determined. It was necessary to decant or siphon the water from the rubber before treating it with the Winkler reagents because free iodine reacts with rubber.
Natural Aging of Reclaimed Rubber
Authors: Palmer Henry F. , Crossley Robert H.
Published: February 2011

As reclaimed rubber undergoes natural aging, it becomes less tacky and more resistant to breakdown during milling. This appears to be true to a lesser degree for reclaims having a high alkalinity than for those with low alkalinity. The acetone extract of reclaimed rubber remains constant as it ages, but its chloroform extract tends to decrease. These changes are accompanied by only small variations in physical properties, as shown by results obtained in typical test formulas. There is no significant change in quality when reclaim up to 18 months of age is used. This was true also of tire treads containing reclaim aged 15 months, as judged by actual road tests.