bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on the Chemical Constitution and Physical Properties of Rubber
Authors: Hock Lothar , Fromandi Guido 
Published: February 2011

Abstract
Some time ago we published the finding that the decrease in the iodine number of rubber on cyclisizing it electrically was accompanied by a marked loss of valuable colloid-chemical properties, and, moreover, that isoprene rubber originally characterized by a low iodine number improved in properties under the influence of the silent electric discharge, while the iodine number increased. These facts suggested that commercially less valuable grades of rubber might owe their inferiority to their essentially lower degree of unsaturation. Therefore the investigation was begun by comparing the known iodine numbers of the best grades of plantation rubber with those of the poorer grades. Pure rubber, as, for example, that prepared by Pummerer's method, is known to have an iodine number very near the theoretical (372.8). In the case of raw rubber each per cent of the rubber hydrocarbon present requires 3.728 units of the iodine number, so that naturally a lower value is to be expected as approximately four units must be subtracted for each per cent of impurity. If we suppose smoked sheets to contain 93% of rubber hydrocarbon, we can ascribe to it an iodine number of only about 347, provided that the impurities do not combine with any iodine, which, however, though not important, is not so. A sample of smoked sheet containing 3.2% of acetone-soluble material and 0.4% of mineral matter besides protein, etc., was found to have an iodine number of 348. Washed Congo rubber containing 5.9% of acetone-soluble material and 1.7% of mineral matter had an iodine number of 329. The iodine number of the acetone-soluble portion was 24, so that 5.9% of extract required approximately 1.4 units of the iodine number; hence the rubber hydrocarbon present had an iodine number of 327.6. If the components of the rubber insoluble in benzene were filtered off and the rubber precipitated twice with acetone and once with alcohol and then dried in a vacuum at 50° C. to constant weight, the iodine number rose to 351.4, thus closely approaching the theoretical value, considering the impurities still present. It is questionable whether or not one may attribute the less valuable properties of this wild rubber to its very slightly lower degree of unsaturation. For the present we shall restrict ourselves to the publication of our results in the following table, with the intention of returning to this question after a detailed examination of a greater amount of material.
The Purification and Fractionation of Rubber. (7th Communication)
Authors: Pummerer Rudolf , Andriessen Albrecht , Gündel Wolfgang 
Published: February 2011

Abstract
I—The Alkali Purification of Concentrated Latex. Nitrogenous Impurities in Latex Preserved with Ammonia It has already been shown that in the purification of latex by alkali, fresh and ammonia-preserved latex behave differently toward alkali. The former is changed even in the cold through decomposition of the proteins (as shown independently by de Vries and Beumée-Nieuwland), whereas the latter first shows evidences of changes at 50°, at which point it creams. Furthermore, experiments with “Revertex”, a concentrated latex, have shown that ammonia-preserved latex is changed in a still different way. Pummerer and Pahl consider the “total rubber”, obtained by them from ammonia-preserved latex by the action of alkali, to be free proteins and nitrogen. This view is, however, open to correction. Total rubber is probably fairly free of proteins, but contains nitrogen. The nitrogen content, which is still appreciable even after prolonged treatment with alkali at 50??, varies from 0.15 to 0.4%. This nitrogen was at first overlooked, because it was not detected in a few qualitative Lassaigne tests, nor in a quantitative Dumas determination. Moreover analysis indicated nearly 100% of hydrocarbon. Nevertheless new tests have shown that many samples contained 0.4% nitrogen. When the samples were incinerated with a reduced copper spiral, there was a deficit of 0.4% in the carbon-hydrogen determinations. Accordingly a substance containing 0.4% protein-nitrogen would show a deficit of about 1% on account of the oxygen in the protein. The nitrogen remaining after the alkali purification of ammonia-preserved latex is not protein-nitrogen but amino-nitrogen, which probably is formed by the action of ammonia during long storage. A gel-rubber (0.4% nitrogen) refluxed in benzene for a day with dilute NaOH yielded no amino acids to the NaOH. The neutralized aqueous solution did not give the ninhydrin reaction, nor did the rubber itself when it was boiled with the reagent.
The Preparation and Molecular Size of Isorubber Nitrone. (8th Communication)
Authors: Pummerer Rudolf , Gündel Wolfgang 
Published: February 2011

Abstract
Continuing earlier experiments of Angeli, Alessandri, and Pegna, of Alessandri and of Bruni, the latter and Geiger have recently studied the action of aromatic nitroso compounds on rubber, and have obtained notable results. The earlier experimentors succeeded only in obtaining from nitrosobenzene a compound of the composition C58H61N5O9. It has recently been proved that one molecule of the nitroso compound for each isoprene nucleus enters the rubber molecule. However, as the earlier investigators have shown, three molecules of nitroso compound react with each C5H8 group when the rubber is warmed in benzene on a water bath for 15 minutes. The solution changes from green to dirty green and finally to brown-red. After cooling it is poured into petroleum-ether, whereupon yellow flakes of the composition [C11H11ON]x, decomposing at 135–140°, separate, the yield being 94–98%. This product is evidently formed by the reaction of one molecule of nitrosobenzene with C5H8 with loss of 2 atoms of hydrogen. This hydrogen reduces a second molecule of nitrosobenzene to phenylhydroxylamine, which with a third molecule yields azoxybenzene. The latter was isolated from the mother liquor. The rubber derivative which is formed may be regarded as a nitrone of an isorubber:
Pigment Reinforcement
Authors: Lunn R. W. 
Published: February 2011

Abstract
This paper considers the reinforcement of rubber by various agents, but the point of view is taken from a rather new position. As a result the familiar conclusions are reached, but the new aspect has some points of interest. The first thing is to define the meaning of the term “reinforcement”, and for the purpose of this paper it is used to indicate energy. The extension of rubber and its compounds involves the input of energy, which increases continuously to a maximum at which breakdown occurs. This paper is a consideration of the energy relationships between rubber and pigment under extension. A familiar way of comparing the reinforcing powers of rubber pigments is to compare the total energies of resilience of the compounds containing the pigments. Pigments are compared on a basis of equal volumes. The resilient energy figures compared are those of the whole compound. For the purpose of this investigation an attempt is made to analyze the total energy value and assign a certain proportion of it to the rubber and the remainder to the pigment. However, it must not be understood that the pigment as such has an energy value like rubber. The addition of pigment causes an energy change in the rubber compound which can be associated with that pigment. To make the idea clearer it may be useful to express it in an elementary mathematical form.
Some Observations on Rubbers with Low Nitrogen Content
Authors: Cummings A. D. , Sebrell L. B. 
Published: February 2011

Abstract
Rubber has been prepared protein-free, although not entirely nitrogen-free, by digesting latex with caustic soda, as recommended by Pummerer and Pahl. Rubbers with a nitrogen content of from 0.004–0.0096 per cent have been prepared by a slight modification of the original procedure. This rubber can be compounded and cured to give good quality vulcanizates, which compare very favorably with the controls. Protein-free rubber, when acetone-extracted, becomes nitrogen-free. This can still be vulcanized, although it cures slowly. The rate of cure of rubber from protein-free latex is affected very little by the pH of the coagulating medium whereas with full-nitrogen rubber rate of cure varies considerably with change in pH value at the time of coagulation. It was also found that protein-free rubber could be racked. Data on the preparation, coagulation and nitrogen content as well as the vulcanization results of protein-free rubber are presented. The observations lead to the conclusion that protein is not the key to the explanation of the physical properties of rubber. Rubber cannot be prepared absolutely nitrogen-free by the method of Pummerer and Pahl, even though the treatment of the latex with caustic is continued twice as long as they recommend. The residual 0.004 to 0.009 per cent of nitrogen is not protein nitrogen, since it is removable by acetone extraction and the amount of nitrogen falls so low as to be unmeasurable with accuracy by the exact method used in this research—i. e., colorimetric determination with Nessler???s solution. The authors note with satisfaction that Pummerer has come to exactly the same conclusion. Comparison of the results of vulcanizing protein-free rubber with those of the controls and with the results of the previous research shows that the rate of cure is constant under different conditions of coagulation and that the quality of the nitrogen-poor vulcanizates compares very well with the controls and with the earlier mentioned work described by Dinsmore. It appears, therefore, that the variation in cure and quality as noted by Dinsmore was due entirely to some particular condition of the rubber protein brought about by the varying pH values existing at the time of coagulation. Protein-free rubber, after acetone extraction, is practically nitrogen-free and cures slowly to give vulcanizates of lower quality than is obtained with the protein-free rubber. It should be remembered, however, that, as stated above, this effect may not be due entirely to the absence of nitrogen. Definite conclusions on this phase of the question must be withheld until more experiments are made. The evidence presented shows that protein-free rubber can be compounded and cured to give good quality products. Hence the protein is not an essential factor in producing the physical properties of vulcanized rubber. The condition of the protein does affect the rate of cure and so exerts an indirect effect upon the quality of the rubber.
Natural and Synthetic Rubber. I. Products of the Destructive Distillation of Natural Rubber
Authors: Midgley Thomas , Henne Albert L. 
Published: February 2011

Abstract
Two hundred pounds of pale crepe rubber have been destructively-distilled at atmospheric pressure. The distillate was fractionated and its components identified from C5 to C10, as shown in the table. Assuming that the Staudinger formula is correct, that the single bonds furthest from the double bonds are the weaker spots and that the formation of six-carbon rings is favored, it has been shown that nearly all of the compounds actually isolated could be predicted. The experimental results, together with forthcoming experimental data, are expected to be used to throw light upon the formula of the rubber molecule.
Natural and Synthetic Rubber. II. Reduction of Isoprene by Na-Nh3
Authors: Midgley Thomas , Henne Albert L. 
Published: February 2011

Abstract
The reduction of isoprene by sodium in liquid ammonia was attempted to determine: (1) whether reduction would take place in preference to polymerization and (2) the location of the added hydrogen. Isoprene was added to sodium dissolved in liquid ammonia and a 60% yield of 2-methyl-2-butene resulted. No other volatile hydrocarbon was found. High molecular weight hydrocarbons were formed but were not investigated. It is thus shown: (1) that the predominant reaction proceeds in accordance with the equation C5C8+2Na+2NH3=C5C10+2NaNH2 and (2) that hydrogen adds to isoprene in the 1,4-position, in agreement with Thiele's theory. The hydrogen addition is similar to the bromination of isoprene at low temperature. If properly conducted the latter reaction stops after 2 atoms of bromine have been added to 1 molecule of isoprene; the resulting compound, 1,4-dibromo-2-methyl-2-butene, is characterized b the inactivity of its double bond toward bromine. Similarly, 2-methyl-2-butene obtained by reduction of isoprene is not reduced to isopentane by an excess of Na—NH3 reagent.
Natural and Synthetic Rubber. III. Dimethyloctadiene
Authors: Midgley Thomas , Henne Albert L. 
Published: February 2011

Abstract
The dimer of isoprene formed under conditions which normally produce “sodium rubber” has been stabilized by the addition of hydrogen. This partially hydrogenated dimer is a mixture of three isomeric dimethyl-octadienes; its formation indicates that the mechanism of the polymerization of isoprene to synthetic rubber is the joining of many isoprene molecules by linkage of the 1,1-, the 1,4- or the 4,4-carbon atoms to produce a long-chain molecule.
Chart for the Estimation of Equivalent Cures
Authors: Brittain G. L. 
Published: February 2011

Abstract
IN ALL heavy rubber articles the temperature conditions which obtain during curing are very different from those existing in light articles. Heat penetrates thin rubber sheets so quickly that they may be said to cure at constant temperature. Heavy articles, however, are heated very slowly, so that their cure may generally be divided into periods of rising temperature, approximately constant temperature, and falling temperature. During August, 1926, the writer developed a method of evaluating and comparing cures made under such variable temperature conditions. The principle is applicable to all cases of variable temperature cures???as, for instance, shoe-curing schedules, etc. Two papers presenting methods of estimating the curing effect of variable temperature schedules have recently appeared. Sheppard and Wiegand have developed equations and charts whereby curing effect may be calculated and expressed mathematically. Their method is based on the empirical relation that the intensity of curing action doubles with every rise in temperature of A° F., where A is a selected constant (in the example given, 15° F.). The method is therefore limited, in exact application, to compounds for which the temperature interval (A) during which the rate of cure (corresponding to intensity of curing action of the schedule) doubles is actually constant. Tests show that for many stocks the interval is not constant over the range of curing temperatures. The procedure is also limited to schedules where the rate of rise of temperature is constant.
Tire Design with Relation to Comfort, Flexibility, and Wear
Authors: Knowland T. M. 
Published: February 2011

Abstract
THIS paper summarizes some of the more important factors in tire design which exert a controlling influence on tire comfort, flexibility, and wear. It is not attempted to add to any of the fundamental principles of tire design already laid down, but it is hoped to give a somewhat clearer insight into some of the simple mechanics and economics of tire behavior. In doing so, acknowledgment should always be made of the important and fundamental work of Schippel and Healy, whose investigations have provided an exhaustive research into tire mechanics. The scope of tire design is so broad that only a very few of the most important phases of it can be treated here. Several hundred specifications enter into the construction and composition of a single tire. Furthermore, the recognized types of tire failures are very considerable in number and may be due to either chemical or mechanical defects, or both. All normal tire failures, however, can be broadly classified as carcass failures, or wear failures, the chemical difficulties being included in both groups.
Temperature Coefficient of Vulcanization on a Litharge Compound
Authors: Sheppard J. R. 
Published: February 2011

Abstract
THE influence of temperature on vulcanization is too well known to require emphasis—it has been generally recognized for quite a number of years that the relation between temperature and time for ordinary curing ranges was logarithmic although there has been no unanimity as to the exact relationship. This doubtless is in part due to the varying experimental conditions employed by the investigators and possibly in some cases to less precise measurements. Table I, a partial bibliography, shows some values for the temperature coefficient which have been obtained and the conditions used. It will be seen that values ranging from 8 to 25 have been reported for the coefficient (in terms of degrees Fahrenheit required to double the rate of cure). It is the purpose of this paper to recount the writer's determination of the temperature coefficient for a given litharge stock in press cures—it is not safe perhaps to infer from the present results what might hold under certain other conditions.
The Value of Reclaimed Rubber in Tread Stock
Authors: Sanderson C. W. 
Published: February 2011

Abstract
The road abrasion value has been determined on a series of tread stocks containing from 0 to 100 per cent. reclaim hydrocarbon. There is a close check between the road value as determined on two different types of road tests. The value of reclaim in this test is shown to vary from 25 to 42 per cent. of the value of new rubber, being higher for the all reclaim stock. The relative cost per unit of abrasion is shown to be above rubber at all points for 20-cent rubber. For 40-cent rubber it is lower than rubber when used above 50 per cent. reclaim hydrocarbon. The relative values for laboratory tests are compared to the road value. The tensible, lamination tear, and the 30 per cent. slip abrasion seem to give the best indication of road value.
Electric Motor Drives for Rubber Machinery
Authors: Crawford R. D. 
Published: February 2011

Abstract
THE B. F. Goodrich Co. began in 1898 to use electric motors experimentally to drive calenders. Since that time there has been a steady addition of motor drives and a marked increase in all the equipment required to meet the additional electric power demand. In 1910–11 certain gear driven calenders were changed over to motor drive. The gear drives on calenders made available only two speeds by means of gear changes. The maximum yardage rate was 18 or 19 yards per minute and the minimum, about half that speed with no possibility of an intermediate speed. It is now possible to make almost any adjustment desired, while speeds have been increased greatly, even up to 50 yards or more per minute. With respect to a calender, heating naturally increases as the friction ratio increases. Thus the stock becomes hotter at higher rates of production necessitating installation of better cooling facilities. For example, changing the friction ratio of a certain calender from 1 1/2 to 1 to 2 to 1, delivery of the same yardage rate was impossible until the calender piping of increased size was rearranged to permit the circulation of an increased volume of water. This increase of friction ratio demanded more power from the motor. It has been found a good rule of thumb that the proportionate increase of power is about equal to the sum of the peripheral speed of the rolls either of calenders or mills.
The Double Refraction of Stretched Rubber
Authors: Van Geel W. C. , Eymers J. G. 
Published: February 2011

Abstract
A relation between the double refraction and the elastic tension of rubber is derived. The formula which is given defines double refraction as a function of tension up to a certain limiting value of the tension, at which point a strict proportionality between double refraction and tension begins. At this limiting tension the elongation is 70 per cent., and it is noteworthy that at just this elongation X-ray photographs of rubber begin to show fibre diagrams.
Time and Temperature-Plasticity Relations for Crude Rubber as Measured with the Goodrich Plastometer
Authors: Dieterich E. O. 
Published: February 2011

Abstract
KARRER (2) has presented the fundamental principles guiding the quantitative measurement of plasticity of materials, and has described a plastometer (1) whose design and operation incorporate these basic principles. The simple relationship between softness, permanent set, and plasticity, when the time interval of compression is kept short, was pointed out. This relationship makes it an easy matter to interpret the results obtained by the use of this instrument and to make intelligent comparisons of different materials, or of the effects of different kinds of treatment of the same material. The results recorded below, all of which refer to crude rubber, and which are typical of rather extensive data, illustrate the applicability of the plastometer to the requirements of the rubber industry, and their bearing on progress in rubber technology is indicated. The plasticities have not been expressed in absolute units, since relative values, based on the changes of dimensions of the sample during compression and recovery, are entirely adequate for factory control work. Multiplying these values by the factor 0.01876 gives the absolute plasticity in kilogram-centimeter-second units.
Effect of Stearic Acid on Various Crude Rubbers
Authors: Fuller E. W. 
Published: February 2011

Abstract
The exact acid content of a compound has an important effect on the physical properties secured with it and there is probably a definite state of acidity for each accelerator, and perhaps compound, which gives the best results with the combinations in question. The naturally occurring resin acids in rubber must be considered in figuring the total available acid in any compound. This is especially important where changes are made from one type or grade of rubber to another.
Adsorption of Stearic Acid by Carbon
Authors: Blake J. T. 
Published: February 2011

Abstract
The equations used in the calculations are based on the assumption that the adsorbed molecules are dipoles and are adsorbed in an oriented condition. That the values check is evidence that the proposed theory of dispersion is correct and that the dispersing agent is in an oriented condition on the surface of the filler particle. It is possible to calculate that the center of the dipole axis is 4.2 A˚ngströms from the filler surface. Since this value is but 20 per cent of the length of the stearic acid molecule, the carboxyl group is the chief contributor to its dipole moment. This would imply that the length of the hydrocarbon chain is probably not critical so far as the dispersing properties of a fatty acid are concerned. The mechanism of the successful dispersion of fillers other than carbon black should be essentially the same. The whole theory throws much light on the essential part that the naturally occurring fatty acids and added stearic acid play in the dispersion of carbon black in rubber and explains why the addition of small amounts of stearic acid to rubber, especially to rubbers deficient in the naturally occurring dispersing agents, tends to produce a better and more uniform product.