bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural and Synthetic Rubber. I. Products of the Destructive Distillation of Natural Rubber
Authors: Midgley Thomas , Henne Albert L.
Published: February 2011

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

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

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

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

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

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

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

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

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

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

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

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.
Some Observations on Carbon Black
Authors: Carson C. M. , Sebrell L. B.
Published: February 2011

Different carbon blacks have certain definite effects upon the vulcanized rubber stocks with which they are mixed. The experiments described herein may be grouped under four main heads: (1) adsorption, (2) effect of heat, (3) reaction with sulfur and zinc oxide, and (4) dispersion or rate of settling. The adsorptive capacity of the black is a measure of the rate of cure of the rubber mix, low-adsorptive blacks giving a faster curing stock than high-adsorptive blacks. An indication of the stiffening action of a carbon black may be secured by measuring the amount of carbon dispersed in a thin rubber cement which cannot be centrifuged out in a given time. The effect of temperatures from 500° to 1200° C. on carbon blacks is to render them highly adsorptive and also to give a rubber mix which cures faster and has a higher modulus. The reaction of carbon blacks with sulfur and zinc oxide in boiling xylene liberates a substance having accelerating properties in a pure gum mix.
Carbon Black. II—The Role of Oxygen
Authors: Johnson G. R.
Published: February 2011

The results reported in this paper confirm the indication of previous work that a portion of the oxygen in carbon black exists in rather definite chemical combinations on the surface of a hydrocarbon with a high carbon-hydrogen ratio. It is not clear yet whether all of the oxygen in carbon black exists in this state, as previous work has shown that after heating for extended periods at 955° C. there still remains a small amount of oxygen in the black. It has been shown that the oxygen attached as here described does not exist in the state of gaseous adsorption and cannot be removed by heat alone as oxygen, but can be removed by reaction with zinc dust at temperatures below that at which gaseous evolution usually takes place. The oxygen goes over to zinc oxide and the volatile matter of the residue is considerably reduced.
Relation between Artificial Aging Tests and Natural Aging
Authors: Bierer J. M. , Davis C. C.
Published: February 2011

THE more varied the uses to which rubber is put, the more varied are the conditions under which it ages, and the less can it be expected that any single aging test will duplicate these various conditions. The most important factors which promote the deterioration of rubber goods are oxidation by atmospheric oxygen, after-vulcanization, heat effects, cracking and other changes from exposure to sunlight, and wear or deterioration due to mechanical work. No two types of rubber products are exposed in just the same way to these various influences; in fact, one product may be exposed to a marked degree to only one of the influences whereas another may deteriorate from all five influences. Thus, automobile tires undergo oxidation, after-vulcanization, heat effects, cracking from exposure to sunlight and abrasion, and deterioration from mechanical work. On the other hand, steam hose tubes deteriorate predominantly from after-vulcanization and heat effects; oxidation, mechanical work and sunlight playing almost no part. After-vulcanization and oxidation are the most important factors in the deterioration of air-brake hose, while auto-topping and bathing caps undergo severe exposure to sunlight. In brief, each kind of rubber goods is exposed to different conditions, and to attempt to duplicate the different combinations of light, heat, oxygen, and mechanical work would lead to a different test for every type of rubber goods manufactured. Obviously, this is impracticable and undesirable.
Correlation between Geer Oven and Natural Aging of Selected Tire Compounds
Authors: Nellen A. H. , Sellers H. M.
Published: February 2011

In standard guanidine tread and carcass compounds, test results obtained from the 4- and 8-day periods in the Geer oven at 70° C. correspond approximately to 1 and 2 years of natural aging. Data obtained from the 12-day period correspond with 3 years of natural aging for tread compounds, but results showed no relation between these same periods for carcass stocks. The tensile product is the criterion which shows the best correspondence between Geer oven tests and natural aging tests on the tread and carcass compounds used.
The Effect of Solvents on the Stress-Strain Curve of Vulcanized Rubber
Authors: Tiltman H. A. , Porritt B. D.
Published: February 2011

(1) The results indicate that the rigidity of a piece of vulcanized rubber is considerably reduced by the absorption of small amounts of a solvent; thus, at a strain of 6 ( = 600 per cent elongation) the absorption of 5 per cent by weight ( = 8 per cent by volume) of benzene lowers the rigidity by 21 per cent. (2) The greatest effect is produced by the first 20 or 30 per cent (by weight) of absorbed benzene, further absorption having a less marked effect on the stress-strain curve. (3) The absorption of solvent seems to have very little effect on the breaking elongation, although the tensile strength is considerably lowered. This conclusion, however, is probably no longer true in the case of rubber swollen by immersion in liquid, where the absorption is very much greater than in the present tests. (4) Absorption of solvent followed by complete drying appears to produce a slight, but technically negligible, permanent effect on the stress-strain curve. It is evident from these results that when it is necessary to use solvents, either in the process of manufacture or the after-treatment of rubber products, these should be selected as free as possible from high-boiling constituents liable to be permanently retained by the rubber with consequent detriment to its strength. A conclusion of some theoretical interest is that since all the stresses in the present investigation were calculated on the dimensions of the original dry rubber, the low rigidity of swollen rubber cannot be ascribed simply to the “dilution” of the rubber by the absorbed liquid, but must be due to a loosening of the cohesive forces between the ultimate particles of the material.
Heats of Combustion of Rubber, Gutta-Percha, and Balata
Authors: Messenger T. H.
Published: February 2011

Though differing superficially to a considerable degree, rubber, gutta-percha, and balata possess so many properties in common that it is difficult to find an acceptable explanation for the respects in which they differ. The chief suggestions postulate differences in molecular structure or in state of polymerization, and since both might be expected to affect the heat of combustion a study of the value of this property is suggested. Before proceeding to a description of experimental work, the position may be illustrated by reference to the more interesting differences and similarities recorded in the literature. In connection with specific gravity it has been found that most raw rubbers, which are hard from being stored a long time in the cold, show a sudden change in the value of this property between 30° and 35° C., when slowly warmed. But on cooling, the specific gravity increases but slowly, and only regains its original value after several months' storage in the cold. This phenomenon has been described by Bunschoten (Mededeelingen van den Rijs-rubberdienst, 3rd series, 1921) and by Pickles (India Rubber J., 67, 69 (1924)). It has been reported by Park (Ind. Eng. Chem., 17, 152 (1925)) that balata behaves similarly, though the time scale is different, being measurable in minutes rather than in weeks, as with rubber.
The Berginization of Raw Rubber
Authors: Waterman H. I. , Dewald R. H. , Tulleners A. J.
Published: February 2011

As a raw material for the experiments, a sample of raw rubber, viz., first latex crepe, was used. This was obtained from the Reichskautschukprüfungsanstalt in Delft, where analysis showed the particular sample of crepe contained 93 to 94 per cent rubber hydrocarbon, with the remaining 6 to 7 per cent composed of 2 to 3 per cent acetone extract, 2 to 3 per cent proteins (calculated as protein with factor 6.25) and finally moisture and ash. When dry distilled in the ordinary way, this crepe yielded up to 450° C. about 95 per cent of a yellow oil which was highly unsaturated. The bromine addition number (according to the McIlhiney method) of the distilled benzine (b. p. up to 220° C.) was, with a 3-minute contact period in carbon tetrachloride in darkness, higher than 120. The benzine obtained from the berginization of the raw rubber was far different from this. The experiments were carried out in an agitated autoclave. Five iron balls served as a means of stirring. In each experiment 150 g. of crepe were rolled around the pyrometer tube in the autoclave. Each time before an experiment, the autoclave was evacuated and was charged with hydrogen at 110 kg. per sq. cm. pressure. Two experiments, D6 and D7, were carried out. For comparison 2 similar experiments, D3 and D4, were made in which hydrogen under pressure was not used, in this case the heating being carried out under the pressure of the gases formed by the thermal decomposition. The conditions used in the D3 and D4 experiments were otherwise identical with those of the D6 and D7 experiments. The heating was carried on so that 450° C. was reached as rapidly as possible, at which point the system was maintained for 15 minutes. At the end of this period of heating, the autoclave was cooled rapidly by compressed air. After cooling the gases were drawn off through a previously evacuated spiral receptacle cooled with a carbon dioxide-acetone mixture. Whatever was not condensed in this way was collected in a gas-measuring receiver. After the pressure in the autoclave had fallen to one atmosphere, the autoclave valve was closed, the cold mixture was removed from the spiral, as a result of which the liquid condensed within the spiral evaporated in part.
An Attempt at a Rational Classification of the Principal Accelerators of Vulcanization. II. A Study of the Time Required for Vulcanization Giving the Maxima Physical Properties at Different Temperatures
Authors: Thiollet R. , Martin G.
Published: February 2011

We have attempted to classify the principal accelerators of vulcanization according to their chief characteristics which are the following: (1) Time necessary for the fixation of mixtures at different temperatures. (2) Times required at different temperatures to obtain vulcanization giving the maxima physical properties. (3) Aging. The first of these 3 items has been treated in Caoutchouc et Gutta-Percha (April, 1929) and we have shown how accelerators can be classified by their “precocity” of action; that is to say, by the rapidity with which they “fix” mixtures at different temperatures. The mixture being fixed, vulcanization continues and the physical quality of the rubber improves. It thus reaches a maximum, then diminishes upon too prolonged heating. In this second study we have attempted to determine the following points: (1) At a given temperature, how long a period of vulcanization is required to impart to the mixtures their maxima physical properties? (2) Within the range of temperatures, which temperature gives the optima physical properties?
The Swelling of Vulcanized Rubber in Liquids
Authors: Scott J. R.
Published: February 2011

The object of this paper is to present some of the results of an investigation of the swelling of vulcanized rubber carried out in the laboratories of the Research Association of British Rubber Manufacturers. It would be impossible in the space available to describe all the work in detail, and what follows must be regarded merely as a summary of the outstanding results obtained, supplemented by references to published literature. The mechanism of the absorption of liquid and the structure of swollen rubber gels are not discussed in this paper; water absorption also is omitted, as it depends mainly on the non-rubber constituents, and therefore differs essentially from the absorption of organic liquids.
The Aging of Cotton Contained in Rubber Goods
Authors: Barr Guy
Published: February 2011

The paper will not deal with the behavior of such textiles as tire fabrics and cords in service and any general remarks made should be interpreted as applying, in the first place, to balloon fabrics, though some of them will not need the restriction. The subject of the permeability of balloon fabrics to hydrogen or to air will not receive attention, as the aging of the cotton has no direct connection with the variations of permeability which occur on exposure. Early Observations on the Weathering of Balloon Fabrics.—Rubbered cotton had been used on the Continent by the end of last century in the construction of balloons, but the authorities here had put their faith in goldbeaters' skin when building small spherical balloons, so that when attention was directed toward dirigibles, this country had to make up considerable lee-way in the study of rubbered fabrics suitable for such purposes. The manufacturing difficulties which are involved in obtaining satisfactory gas-tightness with a limited weight of rubber proved only a temporary trouble. The chief defect of early balloon fabrics was the relatively rapid rate of increase of permeability, but it was recognized that deterioration of the cotton was of vital importance; if an airship did not continue to hold gas well it was liable to fall gradually, but if the cotton had become weakened a burst was almost certain to involve loss of life.
The Relationship between Forces and Deformations. With Special Reference to Rubber
Authors: Ariano R.
Published: February 2011

A matter of great interest and importance in the study of stress-strain relationships is the problem of expressing the behavior of a material in terms of a few constant coefficients, each having a definite physical significance and depending only on the nature of the material. The following is a contribution toward this problem, with special reference to rubber and the analogy between rubber and other materials.
A Spiral Model of Rubber
Authors: Fikentscher H. , Mark H.
Published: February 2011

As a result of the work of Harries, the synthesis of rubber-like substances and the recent X-ray researches of Katz and of Hauser and his collaborators, one is justified in regarding the isoprene residue as the basis of the structure of rubber. The reason it has not been possible to obtain quite 100 per cent. of isoprene from rubber, in the way that cellulose can be converted quantitatively into its parent substance, glucose, is because of the strength of the C-C bonds of the individual isoprene residues of the rubber compared with the more easily cleaved glucoside oxygen bridges in cellulose. Above all, the extraordinarily thorough investigations of Staudinger and his collaborators have contributed important facts about the general behavior of chain-forming molecules, the application of which to rubber leads to the conviction that rubber contains long chains held together by primary valences, called macromolecules by Staudinger, a view which was held by Pickles years ago (cf. Ditmar, Der Kautschuk, 1912). Utilizing the Bragg numbers for the diameter of the carbon atom in organic compounds, Meyer and Mark have proposed a “primary valence chain model” of rubber, which conforms to the X-ray data and to the most important chemical properties. Since its general features have been pretty well confirmed, it seems a suitable time to improve this model, to develop it further structurally and to attempt to make clear the mechanical and other properties of the substance.
Chemical Adsorption Studies of Rubber Fillers and Rubber Compounds. Communication No. I
Authors: Fromandi G.
Published: February 2011

The evaluation of a filler, especially its behavior in a compound, depending on the special considerations to be met, is now judged almost entirely by a systematic study of its physical properties in the compound itself. Results and numerical values thereby obtained, depending on the character of the compound, in the majority of cases permit of no generalizations. However, they do permit certain conclusions which indicate the choice of a particular filler as suitable from a technical point of view. Wiegand obtained some insight into the complicated relationships involved, in the following manner. By a systematic study of the “proof resilience” or work of rupture of a base mix which is characteristically affected by the addition of increasing volumes of various fillers, he was able to show that the reinforcing action of finely divided fillers is primarily a function of their higher degree of dispersion and of the greater surface in common thereby obtained—a finding which was confirmed by the work of North. If, as suggested by Wiegand, the reinforcing action is considered as a function of the amount of filler, introducing the well-known value of “A” and the technically important “ΔA” function, a very clear picture of these relations is obtained.
A Study of the Vapor-Pressure Diminution of Rubber Jellies
Authors: Stamberger Paul
Published: February 2011

Methods and results of measurement of vapor-pressure lowering of rubber jellies are described. From the qualitative behavior of the jellies (consistency), from the shape of the curve given in Fig. 3, and from approximate calculations of the thickness of the solvent layer round the molecules, it is assumed that the solvent is bound by the molecules of the jelly in the form of a solvated layer. The existence of such a layer in the sphere of action of the molecules explains sufficiently a decrease of activity of solvents, which results in vapor-pressure lowering, swelling pressure, etc., and makes the process similar to that of solution.
Studies of Conditions Affecting the Vulcanization of Rubber. III. Some Properties of Rubber against Solvents
Authors: Toyabe Yutaka , Fukunaga Kenji
Published: February 2011

The authors have determined the solubility of unvulcanized compounded rubber containing 20 per cent. by volume of zinc oxide. The obscurometry method described in a previous report on various mixed solvents was used in the experiments. It was observed that the addition of a small quantity of certain solvents such as ethyl alcohol, acetone or nitrobenzene increases considerably the solvent power of the original solvents, such as benzene or gasoline. The results are shown in Figs. 1 to 12. Similar effects were also observed when inorganic bases or organic accelerators were added to the solvent, as shown in Figs. 18 to 27. These phenomena may be explained by Whitby's electroviscous effects (cf. Second Colloid Symposium Monograph, 1925, pp. 16–28). In the process of peptization of raw rubber in benzine-alcohol mixtures, the so-called gel-skeleton of rubber was easily dispersed in benzine with alcohol or an organic accelerator, whereas it was very difficult to disperse in benzene alone, and in the former case many sub-microns were observed under the ultra-microscope.
The Formation of Thin Films of Organic Colloids on Mercury Surfaces
Authors: Keenan R. L.
Published: February 2011

1. A technique has been developed for obtaining thin films of organic colloids on mercury. 2. Several series of cellulose acetates, with varying viscosities and indifferent solvents, were used. 3. In the case of the cellulose nitrates, the limit film thickness varied in an inverse relation with the viscosity of the solutions. 4. Films of rubber and iso-electric gelatin were formed on mercury. 5. Films of the cellulose esters and gelatin were rigid, and condensed, while the rubber films were elastic. 6. The limit thickness increased with increasing complexity of the atom groups
Flexing Test for Tire Carcass Stocks
Authors: Gibbons W. A.
Published: February 2011

THE test about to be described has been in use in this company for about fifteen years, and has been adopted to some extent by the rubber industry, particularly for use with belting. However, in response to various requests for information regarding the details of the test as applied to tire-carcass materials, a brief description of the methods now in use in the company laboratories is given here. The tests consists of taking a strip composed of several plies of fabric and rubber, bending the strip around a hub until its two faces are nearly parallel, applying a weight to the hub so that the strip is pulled taut, and moving the jaws reciprocally so that the strip drives the hub and is moved back and forth around the hub. This is continued until a separation occurs between the plies of the strip. This test, if carried out under carefully controlled conditions, gives consistent results, and it is the purpose of this paper to outline these conditions.
Some Engineering Problems in the Rubber Industry
Authors: Young H. C.
Published: February 2011

It can be safely said that an industry such as the rubber industry produces by its horse power and its man power. Man power easily attracts most attention because its units are so easily seen, checked, and classed, and everybody considers themselves capable of directly controlling and eliminating such units. But thousands of horse power units rove all over our factories, idle and unemployed, except on work of distribution. The man power is recorded even to habit units such as a boy or a girl, each has its own individuality; but the horse power units are considered only in droves, and whole groups are judged lost, whereas they are tearing out bearings, destroying gear teeth by wear, heating up cooling water, spoiling stock, and taking up man units to repair the damage. It is interesting to note the rates of man power to H. P. in various industries:
Aging of Rubber and Its Retardation by the Surface Application of Antioxygens Diffusion Process
Authors: Moureu Charles , Dufraisse Charles , Lotte Pierre
Published: February 2011

THE deterioration of rubber may be due to any one or a combination of a large number of factors, such as oxidation, depolymerization, continued vulcanization, action of heat or light, and so on. The present paper will deal with the preservative action of antioxygens (12, 15) when applied on the surface of articles, and with some general remarks on the use of antioxygens. Comparison of Accelerated Aging Tests The only test not open to criticism is one which measures the aging of an article under actual service conditions and the writers used it in many control experiments. This test has the disadvantage of consuming an excessive amount of time and of not being suitable for a series of studies. Hence the necessity for artificially hastening the deterioration of the rubber articles. This accelerated aging is obtained, as is well known, by the use of such agents as heat, light, or compressed oxygen used separately or simultaneously. There is some doubt as to which accelerated aging test gives results most similar to natural aging.
Thermodynamics of Rubber. I. Rubber as a System of Two Phases
Authors: Ornstein L. S. , Eymers J. G. , Wouda J.
Published: February 2011

In an earlier communication v. Geel and J. G. Eymers published measurements, giving the elongation of raw rubber as a function of the stress per sq. cm. We have repeated the same measurements (Fig. 1) and have determined the changes of width and thickness simultaneously as a function of the stress. The sheets of rubber used in these and in the earlier measurements were prepared by evaporating latex, which had been poured on gelatin. This rubber had therefore not undergone mechanical treatment. Further, in order to eliminate hysteresis as much as possible, a new piece was used for each measurement. The percentage reduction in the breadth and the thickness progresses in a similar way to that of the reduction in length as a function of the stress.
The Thermodynamics of Rubber. II. Temperature Change of Rubber under Adiabatic Stretching
Authors: Ornstein D. S. , Wouda J. , Eymers J. G.
Published: February 2011

In our first communication (Proc. Acad. Sci. Amsterdam, 32, 1235 (1929)) it was shown that the heating effect which takes place in stretched rubber must be due to hysteresis, because from thermodynamic considerations it is obvious that a substance with a positive coefficient of elongation shows a cooling effect. If this is true, rubber without hysteresis must obey the laws of thermodynamics. We have tested this for rubber of the following composition: which we got from Dr. van Rossem of Rijksrubberdienst, whom we heartily thank for his kindness also on this occasion. To determine whether this rubber is free from hysteresis, the following method was used: A piece of rubber was successively loaded more and more, till the elongation was about 250 per cent., and then the load was gradually removed. No hysteresis was shown by the substance. When the rubber is submitted to a force which gives a change of length of this amount, the length of the rubber does not alter with the time. When, however, the elongation is more than 250 per cent., the length changes slightly with the time up to an elongation of 370 per cent.; beyond this elongation no alteration in length takes place again. When, in the case of these large extensions, the force is gradually decreased, the elongations come to much larger values than before, when the same force was applied to the rubber from its zero state. However, this is not an effect of hysteresis, for, however great the force and however long the time might have been during which the force acted (even more than 24 hours), the rubber always momentarily assumed its original length when the weight was removed at once. In Fig. 1 the areas from O to E and from B to C must be ascribed to different phases, and the difference between the graph for increasing and decreasing force can be explained by a retardation of phase. Moreover, the slope of the curve AB can be much steeper as in this case, with a longer time between the application of different forces. Further, the rubber in the region DE is not in a stable state, for a slight impulse affecting the rubber causes the elongation to decrease at once. Since the second phase already shows itself above an elongation of 200 per cent., we have taken all our readings for thermodynamic relation below that elongation. It is known that from thermodynamical considerations one can get the formula for the change in temperature:
Some Properties of Carbon Black
Authors: Parkinson D.
Published: February 2011

The term “carbon black” will be used in this paper to include all the varieties of moderately pure carbon existing in the form of soot. So far as the rubber industry is concerned, four distinct types of carbon black are in general use, as follows: (1) Gas Black.—Sometimes itself called carbon black, made by the incomplete combustion of natural gas, the principal component of which is methane. The flames of burning gas impinge on metal surfaces, on which the black is deposited. (Cf. Neal and Perrott, Bull. No. 192, United States Bureau of Mines, 1922.) (2) Acetylene Black.—Produced by the explosive combustion of purified acetylene in closed chambers. (3) Lamp Black.—Obtained by incomplete combustion of fats, oils, tars, etc. Unlike the gas black particles, which are removed from the interior of the flame, those of lamp black pass through the outer layer before deposition. (Twiss, India Rubber J., 65, 607, 651, 393 (1923)). (4) Thermatomic Black.—Made by thermal decomposition of natural gas out of contact with air. The difference in physical properties of these blacks depends largely on differences in heat treatment during manufacture. They are arranged above in order of the size of the individual particles, those of gas black easily averaging the smallest.
The Testing of Automotive Rubber Parts Assembled under Compression Part I—Deflection under Compression
Authors: Abbott Franz D.
Published: February 2011

Present-day test specifications on automotive rubber parts are not only incomplete and misleading, but entirely lacking in uniformity. This is particularly true of compression and permanent-set tests on automotive mechanical rubber parts assembled under compression. Consequently, an effort has been made to show the urgent need for unification of such methods. Data are presented in Part I to show that high tensile is no criterion of relative resistance to compression set and that hardness is not a measure of deflectability. In addition, deflection and permanent set under compression are greatly influenced by the size and shape of the test piece, the method of cutting the sample, the gage and methods of measuring it, and condition and kinds of surfaces in contact with the test piece. Compression and compression-set testing equipment are discussed, and some newly designed laboratory equipment is described. One piece of apparatus, the compressetometer, has been found extremely useful in making deflection, hysteresis, and set tests. These tests may be performed under constant load or constant distortion. The constant-load (spring) compression-set clamp is suggested as a suitable laboratory standard for permanent-set testing under compressive loads.
Cryoscopic Measurements of Rubber Solutions and the Separation of Mixed Phases from Benzene Solutions of Rubber. [9th Communication]
Authors: Pummerer Rudolf , Andriessen Albrecht , Gündel Wolfgang
Published: February 2011

We consider the separation of mixed phases in cryoscopic investigations of colloidal systems and of rubber mixtures in particular as a dangerous source of error. Therefore we place no importance on the great variations in the depressions which occur with sol-rubber in benzene. The menthol values vary less, but nevertheless more than usual. The depressions of camphor fusions proceeded strictly stoichiometrically and led to almost the same value (about 1200) as the cryoscopic menthol measurements. In both the latter instances the composition (rubber content) of the crystallized phase has not yet been studied, since the experimental difficulties involved in the separation of the crystals from the viscous fusion liquid have not yet been overcome.
Isoprene and Rubber. XIX. The Molecular Size of Rubber and Balata
Authors: Staudinger H. , Bondy H. F.
Published: February 2011

It was shown in the preceding work that a very dilute solution of balata in an organic solvent contains macromolecules in solution and not micelles. The same is true of rubber. On the basis of these findings it is possible to calculate the molecular weight of rubber and balata from viscosity measurements by means of the formula developed in a previous work: M=η8p/c. Km. The supposition is made that the molecules of rubber and balata have the form of threads and double threads, respectively. Also it is necessary to determine the constant KKm, and this may be calculated in the case of low molecular products, where the average molecular weight can be determined as well as the viscosity of the solutions. Such semi-colloidal decomposition products were obtained by heating rubber or gutta-percha in either tetralin or xylene. As shown by the following table the four samples thus obtained gave the constant: 0.3×10−3,5
The Constitution of Rubber According to Its Swelling in Liquids
Authors: Bary Paul
Published: February 2011

In various publications we have previously shown that in many cases it is advantageous to consider jellies as formed of a polymerized colloidal substance, the length of the molecular chains being easily changed according to the conditions of the system and unlike one another at all times in a single sample. These chains retain free affinities at their extremities to which can be linked so-called solvating groups arising from the solvent or from soluble substances contained in the jelly. The present work refutes the interpretation given to recent experiments on the vapor pressure of jellies and confirms in certain new ways this constitution. (1) The experiments of Stamberger on the vapor pressure of rubber jellies and their consistency before and after a prolonged mastication do not support the Harries hypothesis on the stability of the rubber molecule, but merely show that the theory of true liquid solutions is not applicable to jellies. (2) Based on the idea that polymerization changes with solvation, it is easily shown that the relative swelling in a solvent and in its saturated vapor are not contradictory with the principles of thermodynamics, as it would seem, but on the contrary proceed normally and could have been predicted. (3) In the study by Scott on the slow but unlimited swelling of rubber beyond the saturation point, this author has come to assume that swelling is a double phenomenon, which confirms our point of view. (4) The experimental study of the contraction of rubber during swelling shows that this effect does not change its sign at any moment and that consequently the change of sign of the heat evolved in this same process has a cause distinct from that of the initial swelling; perhaps it is to be attributed to the chemical phenomenon of solvation.
Isoprene and Rubber. Part 20. The Colloidal Nature of Rubber, Gutta-Percha, and Balata
Authors: Staudinger H.
Published: February 2011

I. The Molecular Weight of Rubber, Gutta-Percha, and Balata In the preceding work the molecular weight of rubber and balata was calculated on the basis of relations between specific viscosity ηsp and molecular weight which are shown by semi-colloidal decomposition products, on the assumption that this relation is also true for eucolloids. The value ηr−1 was taken as the specific viscosity, i. e., the characteristic viscosity increase of a substance of definite concentration and known solvent. The expression “specific viscosity” has already been used by J. Duclaux. In viscosity investigations of nitrocellulose solutions he represents this by a constant K which is calculated from the relations of the change of viscosity at various concentrations derived by Arrhenius: Based on these constants, nitrocelluloses show different average molecular weights for the increase in viscosity, that is, this constant K is greater with high molecular products than with low. In the following, this constant represents not the specific viscosity, but the viscosity-concentration constant Kc; the earlier constant Km which, on the basis of the formula: expressed the relation between the specific viscosity and the molecular weight, is called the viscosity-molecular weight constant.
An Investigation of the Viscosity of Rubber Solutions
Authors: Blow C. M.
Published: February 2011

Viscosity measurements have frequently been made with rubber, and very many suggestions have been put forward to explain the cause of the changes of viscosity in rubber solutions. According to Staudinger (Kautschuk, 5, 128 (1929)), if measured under certain conditions, e. g., in dilute solutions where no irregularities are found, the viscosity can be used as a measure of the molecular weight of the dissolved substance. Fickentscher and Mark (Kolloid-Z., 49, 140 (1929)) even calculate from viscosity measurements the length of the molecule and hence relative molecular weights. It is well known that the viscosities of rubber solutions differ greatly and that mechanical treatment of the rubber decreases the viscosity of its solutions to a very large extent. The latter effect has been explained by Staudinger as well as by Fickentscher and Mark (loc. cit.) as a depolymerization. The latter authors calculate that the molecular weight of rubber decreases to one-third of the original if it is masticated for 225 minutes. It has further been pointed out recently by Herschel and Bulkley (Kolloid-Z., 39, 291 (1926)) that rubber solutions show irregularities in their viscosity, e. g., the viscosity is not linearly proportional to the pressure. (According to Poiseuille's formula for the rate of flow of a liquid through a capillary, the viscosity coefficient: