bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Practical Methods of Measuring Gauge at the Calenders
Authors: Dieterich E. O.
Published: February 2011

A LITTLE reflection will immediately establish the fact that it is necessary to control, in some manner, the thickness of practically every stock delivered by a calender, and that this control is indicated by the twin considerations of quality and cost. As an illustration, consider coated fabrics used for tire carcass construction. From the standpoint of quality the skim coat applied to the fabric during calendering must be of sufficient thickness to insure adequate insulation between the plies in the completed tire. Not only must the average thickness be more than a certain minimum but it must be uniform, for non-uniformity results in heavy gauge in some regions and light gauge in others, the latter being a fruitful source of failure by ply separation in service, on account of excessive stresses developed by loading and traction. On the other hand, a skim coat which is too heavy may actually lead to deterioration in quality by introducing defects caused by increased difficulty in tire building. Another example that may be cited is the tread slab, tubed or calendered. Light gauge here may result in incomplete filling of the mold, producing blemished tires ; on the other hand, a tread slab that is too heavy may cause a more serious defect, buckled carcass, due to excessive rind at the mold register. In the case of solid tires, correct gauges are of utmost importance.
Chemical Reactions in Rubber Compounds. I. Reactions between Pine Tar and Litharge
Authors: Reece W. H.
Published: February 2011

The results of the experiments indicate that when litharge and pine tar are present in a rubber mixing, a chemical reaction takes place which does not appear to differ from that which occurs between litharge and pine tar in the absence of rubber. The figures obtained are also in agreement with the assumption that the reaction is one in which the acids present in the pine tar react with the litharge to form soaps. It has been shown that the pine tar contained 46.9 per cent of acids which reacted with litharge to produce 2.45 per cent of water.
Meaning and Measurement of Plasticity
Authors: Karrer E.
Published: February 2011

ALTHOUGH the word “plasticity” is widely used in the arts and sciences, it has no definite quantitative meaning (6, 7), yet the plastic properties of matter are of enormous importance in many industries. As scientific study of materials has increased, it has become more and more desirable to attain to a clearer idea of what is involved in this concept, to the end that plasticity may ultimately be quantitatively defined and measured. The emergence of the word from common usage into the realm of technical words with well-defined meaning for quantitative considerations has been accompanied by considerable difficulty and confusion. Plasticity does closely relate to other properties of materials and the phenomena wherein plasticity may be an important factor are so varied that the role it plays may be overshadowed by and confused with the interplay of elastic and hardness phenomena on the one hand, and permanent set and viscous flow on the other. Reference to a few comments found in the literature will convince anyone of this. Van Rossem and Van der Meyden (14) have pointed out that plasticity involves more than deformation— that the amount of recovery is an essential element. Some seem to indicate that plasticity is synonymous with softness (11), or permanent set (14). Frequently the flow involved in the deformation is the all-engaging aspect and considerable confusion with viscosity has resulted (1, 2, 16). Inverse flow, or recovery, or “revertibility” is also to be considered. Loose and contradictory usage of the term exists in the rubber industry (12, 14, 15). A few attempt to use the term with the usual common-sensical meaning (5, 8).
Discussion
Authors: Boggs C. R.
Published: February 2011

Doctor Blake has suggested a theory for the mechanism of filler dispersion and reënforcement. However, he deals only with carbon black in rubber. Carbon black is the most important reënforcing ingredient we have for a tire-tread compound. Being a conductor, it cannot be used in appreciable quantities in insulation. We might consider the possibility of finding a non-conducting reënforcing filler for insulation and also what should be done when the present supply of natural gas is depleted. What is needed is a material similar to clay which is cheap and has a small particle size. With present dispersing agents, clay does not, however, reënforce rubber to anywhere near the extent that carbon black does. For a filler to reënforce satisfactorily it must be well dispersed and adhere firmly to the rubber. The correct dispersing agent should bring this about. This agent should be a polar compound. One portion of the molecule should be soluble in the rubber hydrocarbon and another portion should be capable of being adsorbed by and adhering strongly to the surface of the clay.
Aging of Mechanical Rubber Goods Stocks by Various Methods
Authors: Soule K. J.
Published: February 2011

THIS paper records the aging of thirty typical mechanical rubber goods stocks, all of which are, or have been, in regular factory use over long periods of time. The times of aging used are 1 year of natural aging in the dark; 24 hours and 48 hours in the oxygen bomb at 60° C. and 300 pounds (21 kg. per sq. cm.) pressure; and 96 hours at 70° C. in the Geer oven. These stocks are arranged in three groups: (1) lightly compounded, three stocks; (2) medium compounded, twenty stocks; and (3) heavily compounded, seven stocks. The physical properties studied are tensile strength, elongation, tensile product, and modulus. The percentage increase or decrease in each of these properties after each type of aging is recorded. (Tables I to III) Figures 1 to 6, inclusive, show graphically the changes in the physical properties studied on each of the three lightly compounded stocks, using several different methods of presenting the data.
Some Notes on Artificial Aging Tests for Rubber
Authors: Vogt W. W.
Published: February 2011

FROM a strictly quantitative point of view we should expect an artificial age test to duplicate in all respects the changes that take place on natural aging. In other words, all of the measurable physical and chemical properties should be changed in the same direction and to the same degree for all types of compounds. if we are looking for such performance from an artificial aging test, then in the writer's opinion none of the present tests fulfil these conditions to a sufficient degree to warrant any extensive use of correlation factors. It must, moreover, be realized that the present methods of artificial aging seek only to duplicate the natural aging of rubber on shelf storage in the dark. If we wish information that will predict aging of rubber products under their normal service conditions, then we must get into the field of specialized testing wherein the conditions with respect to light, temperature, humidity, etc., may be made to approach more nearly those of the actual service.
Quebrachitol from the Serum of Hevea Latex
Authors: Levi T. G.
Published: February 2011

A new procedure for the separation of quebrachitol from the serum of the latex of Hevea brasiliensis is described, and three new esters of quebrachitol are prepared.
Color Reactions of Rubber and Gutta-Percha
Authors: Kirchhof F.
Published: February 2011

A previous article of mine entitled “Observations on Color Reactions of Rubber and Gutta-Percha” has led to the question whether intensely colored reaction products which are obtained by fusion of phenols with bromides of hydrocarbons give characteristic absorption spectra. I have carried out a few preliminary experiments on this subject, which appear to confirm my earlier point of view that the cause of the different colorations is to be found in dispersion color reactions. It is well known that when rubber bromide or gutta-percha bromide is suspended in carbon tetrachloride and is heated with phenol until the carbon tetrachloride is eliminated, a red-violet to blue fusion mixture is obtained, which gives colors of various stabilities depending upon the solvent into which the fusion mixture is dropped. Thus the blue and violet colorations in chloroform are stable for some time, but they change gradually to green and then to brown, with separation of a flocculent precipitate. Yellow-brown reaction products (hydroxyphenylhydrorubber and gutta-percha) are however obtained in the presence of catalysts (iron, aluminum chloride) or by the action of alkalies (NH3, KOH) or by pouring the blue-violet fusion mixtures into ether.
Structural Differences in Masticated and Unmasticated Raw Rubber Mixtures and Vulcanizates, and Their Significance from a Practical Point of View
Authors: Hauser E. A. , Hünemörder M.
Published: February 2011

The use of latex in certain branches of the rubber industry is even today looked upon with a great deal of skepticism in technical circles. This point of view rests not so much on ignorance of actual progress in this field as on the still prevalent idea that a mixture of latex and fillers can never give a useful product and one comparable in quality with a raw rubber mixture. This belief is based on the fact that latex is a decidedly heterogeneous system, since the rubber in latex is distributed throughout in the form of individual particles. In spite, however, of this current belief there is now satisfactory evidence to show that products made from latex mixtures without mastication of the rubber are superior in almost all their physical properties to products made from raw rubber in the conventional way. This superiority is in evidence particularly in the higher tensile strength and elasticity and in the incomparably better resistance to tearing. The experiments to be described, which are based in part on work already published elsewhere and on still unpublished investigations of Miss Hünemörder and the author, will serve to make clear the theoretical basis on which these facts rest and will furthermore indicate a few points which in our opinion are worthy of special consideration in the preparation of latex mixtures.
Condensation Products of Aminophenols with Aldehydes
Authors: Levi T. G.
Published: February 2011

In the present note condensation products of the simpler aminophenols with aliphatic and aromatic aldehydes are described The condensation products with aldehydes and 2,4-diaminophenol are of particular interest because the latter is so unstable that so far as known it has not been directly isolated. Some of these condensation products may well have useful applications in the rubber industry.
The Coefficients of Friction between Rubber and Other Materials. Frictional Grip of Rubber-Tired Wheels
Authors: Ariano R.
Published: February 2011

(i) The coefficients of friction (ƒI and ƒnI) of rubber tires on dry non-dusty surfaces are practically independent of the load on the wheel, and (with pneumatics) of the inflation pressure; on muddy surfaces the coefficients (especially ƒnI tend to decrease with increasing load. (ii) Dust, mud, or water reduces the friction with rubber tires, but not with iron tires. (iii) The tread pattern reduces the friction on dry surfaces, but increases it on muddy surfaces. (iv) There is no systematic difference between pneumatic, semi-pneumatic (cushion) and solid tires as regarda coefficient of friction; the details of individual design and material are the deciding factors; this is in agreement with the results of Bredtscheiner (Verkehrstechnik, 1922; see Schaar, “Die Beanspruchung der Strassen durch die Kraftfahrzeuge,” Zementverlag, 1925). (v) There is no simple relationship between the coefficient of friction and the compressibility or area of contact of the tire. (vi) The static friction perpendicular to the direction of travel is greater than in this direction. (vii) The coefficient of friction depends on the type of road surface, its de-formability, and especially on the presence or absence of dust, mud, or water. (viii) Rubber tires have a much higher coefficient of friction than iron tires, especially on dry hard surfaces. (ix) The static friction is 10 to 20 per cent higher than the dynamic friction.
Transformation of Energy by Rubber
Authors: Williams Ira
Published: February 2011

The data which have been presented indicate that elasticity is a property of rubber which persists through vulcanization and is not created to any great extent. The physical state of the rubber after any period of cure depends on the balance between suppression of plastic properties either directly or indirectly through the influence of combination of sulfur, and the creation of plastic properties through the influence of heat. It is probable that sulfur also combines at a slower rate with the elastic portion of the rubber and finally results in a product of almost no mechanical strength. The transformation of energy by rubber depends upon the condition of the rubber as well as on the condition of the test. Heat liberated by elastic strain can be transformed almost quantitatively into mechanical work. Heat due to internal-frictional resistance which will be caused by both plastic and elastic flow is not reversible. Any reduction in time required for the transfer of energy reduces the amount lost through plastic flow. An increase in temperature increases the resistance of the elastic portion to strain, but also reduces the resistance to flow of the plastic portion. Sufficient increase in temperature causes a large energy loss due to a considerable but limited permanent flow of the rubber. This cannot be plastic flow of the elastic portion, since it is limited in extent, but can better be explained by some mechanical change such as a breaking of the anchorage between portions of the plastic material and elastic network.
Permeability of Rubber to Air. I—Effect of Temperature, Pressure, and Humidity
Authors: Morris V. N. , Street J. N.
Published: February 2011

Apparatus and procedure are described for investigating the influence of temperature, pressure, and humidity upon the capacity of rubber membranes to retain air under pressure. The relation between total pressure and permeability has been found to be almost linear, the permeability being approximately proportional to pressure. The temperature coefficient of permeability is very high, thus indicating that the pressures of inner tubes should be checked much more frequently in summer than in winter. Moisture has been found to decrease the permeability of rubber to air slightly under certain circumstances. Prolonged immersion of the rubber in water, however, resulted in an appreciable increase in permeability.
Moisture Content of Carbon Blacks
Authors: Plummer William B.
Published: February 2011

A METHOD for the determination of total moisture in carbon blacks recently proposed (1) involves mixing the sample (5 grams) with 25 cc. of dry xylene and 200 cc. of dry mineral oil, heating to 175° C., passing dry nitrogen through the system until the xylene and water have been displaced from the carbon black-oil mixture, and continuing the nitrogen stream until all water has been displaced from the intermediate xylene receiver and absorbed in the final CaCl2 tubes. By this method values of 3.54–5.96 per cent. total water are obtained for channel blacks, whereas the same samples showed only 1.42–1.85 per cent. loss on ordinary drying for 6 hours at 105° C. The moisture content of carbon blacks is an important factor in many of their uses, so that the discrepancy between this and the usual oven drying method becomes a matter of practical importance as well as theoretical interest. Hence it has been further investigated. Various types of blacks on heating in a 1-2 mm. vacuum show widely differing weight losses, as illustrated by the results in Table I.
Vulcanization of Rubber. By Organic Peroxides or by Ammonium Persulphate
Authors: Ostromislensky Iwan
Published: February 2011

1. Organic peroxides vulcanize rubber not only in the absence of sulphur but likewise without any foreign substances such as metallic oxides or accelerators of any kind. 2. Rubber vulcanized by means of an adequate amount of benzoyl peroxide (10 to 30 per cent.) gives a soft rubber product which does not differ in point of physical properties from products cured with sulphur, or rather with sulphur chloride. 3. The process of vulcanizing rubber with benzoyl Superoxide is completed in a relatively short time even at a fairly low temperature, sometimes even in two minutes at 119° C., corresponding to 13 pounds pressure. 4. Vulcanization of rubber by means of peroxides may lead to the formation of a soft, transparent and elastic product, which is almost entirely colorless. 5. The products in question vulcanized by means of various peroxides are gradually converted to a very sticky and viscous mass. 6. Sulphur protects the vulcanizates in question from such decomposition or oxidation. However, the products obtained in vulcanization of rubber with organic peroxides in the presence of sulphur are opaque. 7. As distinguished from sulphur, selenium, tellurium, their sulphides, metal oxides (in particular, lead oxide) as well as amines (aniline), tannic acid, and metallic aluminium powder not only do not protect the peroxide vulcanized rubber products from decomposition or oxidation but, on the contrary, they accelerate such processes quite considerably. 8. Benzoyl peroxide is the active vulcanizing agent in the process of heating rubber with a mixture of sulphur and benzoyl peroxide. 9. When rubber is subjected to the action of a mixture of some nitrobenzenes and benzoyl peroxides, vulcanization is effected exclusively by the nitrobenzenes, and the benzoyl peroxide remains altogether passive. 10. Ammonium persulphate vulcanizes rubber completely, resulting in a porous product which, generally speaking, is of small practical value.
The Influence of the Principal Accelerators of Vulcanization on the Preservation of Rubber
Authors: Thiollet R. , Martin G.
Published: February 2011

In the April and October, 1929, issues of le Caoutchouc & la Gutta-Percha the authors have shown that accelerators of vulcanization can be classified according to: (1) their precocity, (2) their temperature of normal action (characteristic temperature), and (3) their rapidity of action at the characteristic temperature. The “plateau of vulcanization” was studied for each accelerator. In order to complete the work it has been necessary to study the influence of the principal accelerators of vulcanization on the preservation of rubber. This article gives the result of these experiments. Mixtures of “pure gum” type were prepared, containing the principal accelerators of vulcanization, taking as a basis the following mixture:
The Pneumatic Tire in Heavy Transport
Authors: Healey A. , Bond W.
Published: February 2011

The last seven years have seen the beginning of a new era in heavy transport. Hitherto road transport had been confined to services where it was not economical to lay down a railway track, where the distances were comparatively short and loads comparatively light, and where the lorry could handle goods in special ways not possible on the railway, e. g., in the removal of merchandise direct from gate to gate of factories without wasting time. Today the situation is quite different. The reduced profits of railway companies are ascribed to the competition of road transport and those companies are extending their sphere of operation, not so much by building new tracks, but by the simpler and less costly expedient of running road vehicles. There can be no doubt that the tire manufacturers have been largely responsible for this revolution. Their production of the giant pneumatic tire was the first step, for without this accessory, modern road transport, and modern types of road vehicles, would be unthinkable. The technical reasons for this provide interesting study to engineers, and should indeed be properly understood by all who are interested in the engineering and operating sides of transport problems, if the fullest advantage of tire equipment is to be obtained.
Factors in the Works Control of Plasticity by the Williams Method
Authors: Garner T. L.
Published: February 2011

Two methods are available for the measurement of plasticity in the works— the Williams and the extrusion method. Generally, when the former is used, the original method is modified in some way, the following being used in this case. The plastometer, with a long handle so that it can be operated through a hole in the roof of the oven without opening the oven door, is used with a loose die, the size being varied according to plasticity, but for routine testing of masticated rubber a 3/4-in. disc 1/4 in. thick is used. The sample of rubber used is rather less than 1/4 in. in thickness to prevent the rubber creeping round the die and touching the top plate when the die is pressed into it; the size of test piece is about 1 1/2 in. square. The samples are cut off masticated rubber plied up to give a thickness of about 1 1/2 in. Each morning the plastometer is set so that when resting on the steel die alone a reading of 400-thousandths of an inch is shown. This means that with the die on a sample of rubber, no indication is given on the plastometer gage until the thickness of rubber between the bottom plate and the die is 400-thousandths of an inch, i. e., a constant thickness in each case. As soon as this is reached, and the gage hand moves, a stop watch is begun and the time taken for the hand to cover 50 divisions on the gage is taken as the plasticity figure. An agreement can be obtained under ordinary working conditions of about ten seconds, and the test does not require skilled control.
Rate of Cure of Reclaimed Rubber—II
Authors: Kilboura F. L. , Miller G. W.
Published: February 2011

Residual alkali in reclaim is chiefly responsible for the faster rate of cure of stocks containing reclaimed rubber as compared with those containing new rubber only. Reclaim prepared in water can be made to cure as fast as alkali reclaim by the addition of sodium hydroxide to the extent that this is present in the alkali reclaim. The determination of residual alkali requires a very long extraction, in this case approximately 60 days. Of five possible theories accounting for the rapid rate of cure of reclaim, only that of residual alkali is tenable. There still remains in certain cases, however, a difference in rate of cure between stocks containing new rubber and those containing water-cooked reclaim for which no explanation has been found. Sodium hydroxide of itself is not deleterious to rubber compounds, for, in addition to its value as an accelerator in certain cases, it tends to improve physical properties and aging resistance, as judged by the Geer oven test.
Estimation of the Degree of Penetration of Rubber into Fabrics
Authors: Dieterich E. O.
Published: February 2011

IT IS frequently important to know to what extent fabrics are impregnated with rubber in the course of manufacture of various fabric-rubber combinations, such as tires, belts, footwear, etc. Such information is of value in answering questions relative to fabric fatigue in service, adhesion, resistance to corrosion, and others. Direct microscopic examination of thin sections of fabric-rubber structures presents mechanical and optical difficulties, chief of which is the practical impossibility of cutting perfect sections. The lack of optical contrast between textile fibers and many rubber compounds is another objection to this method which differential staining has not successfully overcome. Etching the surfaces of thick sections and examination by reflected light are only partially successful in securing the requisite detail. The method described has been used in this company's laboratories for several years with considerable success. It is simple, relatively rapid, demands no equipment beyond that found in the average laboratory, and requires no unusual degree of skill.
Determination of Total Moisture in Carbon Blacks
Authors: Carson G. M.
Published: February 2011

IN THE course of an extended research on various grades of carbon black, determinations of total moisture were made by an adaptation of an old method. The method used was similar to one described by Allen and Jacobs (1) for measuring water in tar. The chief difference in the present method is that small amounts of moisture in carbon blacks must be weighed, whereas the larger amounts in tar could be measured. The difficulties in weighing the evolved moisture are described in the ensuing method of determination. Five grams of carbon black were placed in a 500-cc. round-bottom flask with 25 to 35 cc. of dry xylene and 200 cc. of dry mineral oil. A short air condenser led to the bottom of a 25-cc. distilling flask, which in turn was connected to two or more calcium chloride tubes. The flask containing the sample was heated to 150-175° C. in an oil bath, a stream of dry nitrogen being passed through the apparatus. The water and xylene were distilled into the small distilling flask and thence, by warming in a water bath, into the calcium chloride tubes, the current of nitrogen being continued. It required but a few minutes to remove the water from the xylene, indicated by the disappearance of cloudiness, and the calcium chloride tubes were then connected directly to the nitrogen line and the gas was passed through until the tubes reached constant weight. ylene is not adsorbed by calcium chloride and nitrogen does not remove water from it at room temperature during the time required for the experiment. The increase in weight of the calcium chloride tubes is the amount of water in the sample of carbon black. The amount of water thus determined is considerably higher than the 105° C. oven loss in 5 hours, and indicates that most of the moisture is of the “bound” or “capillary” type.
The Swelling of Latex
Authors: Evers F.
Published: February 2011

The swelling phenomena of latex in organic liquids such as benzene, toluene, or xylene were studied. As factors in the swelling power the following were observed: (1) the ammonia content of the latex; (2) the formation of a boundary layer in the surface of contact of both liquids. Ammonia-rich latex on contact with aromatic hydrocarbons forms a boundary layer which in turn swells, with a great increase in volume. Latex poor in ammonia forms no boundary layer and therefore does not swell. On the other hand, the hydrocarbon may diffuse into the latex without disturbing the Brownian movement. Subsequently the diffused hydrocarbon is able to bring about the swelling of the individual latex particles.
Studies of the Aging of Vulcanized Rubber. X.—The Relation between Degrees of Oxidation of Vulcanized Rubber and the Occurrence of the Maximum State of Acetone Extracts
Authors: Yamazaki Takeji , Okuyama Karoku
Published: February 2011

(1) Using the rubber-sulfur mixture and the mixture containing accelerator and zinc oxide, the relation between the maximum state of acetone extracts and the degree of oxidation was studied quantitatively. (2) In carrying out the above experiment, the samples previously extracted were used in order to accelerate the oxidation and to eliminate the influence of the free sulfur and rubber resin, etc. The aging was conducted at 70° C. for the rubber-sulfur stock and 70° C. and 90° C. for the stock containing accelerator and mineral filler and the increase of weight and the amount of the acetone extract were measured at definite intervals. The maximum state occurred in both cases, but for the case containing accelerator and filler the occurrence was comparatively slow. The decrease of acetone extract after the maximum state was shown to be due to partial formation of some acetone-insoluble products in the aged vulcanized rubber when oxidation proceeds considerably. (3) From the elementary analysis made on the aged samples from which acetone-soluble oxidation products were previously removed, it was shown that the oxygen content in these samples increased as aging proceeded.
The Solvation of High Molecular Substances, Especially Rubber
Authors: Stamberger P. , Blow C. M.
Published: February 2011

1. On the basis of new experimental data on rubber, the theories of the solvation of high molecular substances are discussed. 2. In this discussion the measurements of the swelling pressure of rubber in toluene are described. The values obtained, and also the measurements of the depression of the vapor pressure lead to the conclusion that rubber cannot be considered a mixture of homologous polymers. 3. The consistency or viscosity of gels is without effect on the decrease in the activity of the solvent (measured by the depression of the vapor pressure and the swelling pressure). 4. The conclusion is drawn that mastication cannot be considered a depolymerization. 5. On the basis of measurements of the viscosity of solutions of rubber-gas black compounds it follows that conclusions as to the molecular weight of the dissolved phase cannot be drawn from viscosity measurements without further ado. 6. The theories of the distribution of high molecular substances in solution are briefly discussed.
Isoprene and Rubber. XVII. The Fractionation of Balata
Authors: Staudinger H. , Bondy H. F.
Published: February 2011

On the basis of earlier experiments with synthetic materials, compounds of high molecular weight are not composed of a single substance, but consist of a mixture of homologous polymers. The individual members of a polymeric homologous series differ very little in physical and chemical properties, and therefore a mixture of polymeric homologous products such as is obtained in the polymerization of the monomer cannot as a rule be decomposed into simple compounds by means of solvents, but merely into mixtures of products of low and high molecular weight. Such separations have been carried out, for example, in the case of polyvinylace-tates, polystyrols, polyindenes, polyanetholes, and polyethyleneoxides. On the basis of these experiments it was assumed that natural products of high molecular weight likewise consist of a mixture of polymeric homologs. Thus purified rubber, for example, according to our views is not such a completely homogeneous hydrocarbon that all the molecules have the same length, but consists of a mixture of perhaps 100 or more polymeric homologs. Pummerer's decomposition of rubber into sol,- and gel-rubber, according to our experiments, is due to the fact that rubber consists of easily soluble polyprenes and difficultly soluble polyprenes, all belonging to the same polymeric homologous series. Of course there is the possibility that, in forming compounds of high molecular weight, nature produced primary molecules of uniform size, and that the mixture of polymeric homologs was formed only later through decomposition. In that case the natural products would differ in constitution from the synthetic material. They would not be polymerically uniform but completely uniform compounds in the sense of classical organic chemistry. The fact that in life processes methods are possible which we cannot realize in the laboratory is well known. Such a finding would not, of course, contradict our former view that natural products, such as rubber and balata, are of high molecular weight in the sense of classical structural chemistry. Our former work has indicated a similar structure for rubber and gutta-percha. Here it is simply a question whether or not the macromolecules of these natural products have a uniform length. In order to reach a decision, we first of all investigated balata, since it is prepared pure more easily than rubber. It was made from balata latex which was supplied to us through the courtesy of the management of the Norddeutsche Seekabelwerke, Nordenham." The balata thus obtained is a flocculent, cellulose-like mass, which looks like gutta-percha and crystallizes like it.
Isoprene and Rubber. XVIII. Viscosity Studies on Balata
Authors: Staudinger H. , Leupold E. O.
Published: February 2011

Varied views prevail as to the structure of the colloidal particles present in a rubber solution. According to Harries, Pummerer, and many others, these colloidal particles are formed through the association or aggregation of smaller molecules. According to Meyer and Mark they have a micellar structure, the micelles forming through the apposition of main valence chains. On the other hand, it was assumed by one of the present authors that the elementary particles in a colloidal solution of rubber are identical with the rubber molecules, these large, especially labile molecules being called macromolecules. Thus the existence of much larger molecules than any hitherto known was postulated. This view was confirmed by the conversion of rubber to hydro-rubber capable of forming colloidal solutions, and also by the pyrogenic decomposition of rubber. In order to decide definitely between the two conceptions, the stability of the colloidal particle in a rubber solution was studied by means of viscosity measurements at various temperatures as was done in the case of the polystyrols. If these colloidal particles form aggregates or if they have a micellar structure, they should decrease in size with increase in temperature, and this change should be evidenced by a diminution of the specific viscosity of the colloidal solution. On the other hand, if such a solution is composed of molecules, the specific viscosity at various temperatures is the same, provided that the molecules are not decomposed at higher temperatures. This line of research led to an explanation of the constitution of the colloidal particles in a polystyrol solution and was now applied to balata, since the latter is especially easily purified.
The Strength and Stretch of Double Texture Rubber Goods
Authors: Knowland T. M.
Published: February 2011

RUBBER articles may be divided roughly into three classes: (1) pure gum, (2) hard rubber, and (3) various combinations of rubber and textile fibers. This latter class is the largest and possibly the most important of the group, and includes besides tires the bulk of mechanical goods, such as hose, belting and sheet goods of various kinds. Probably no combination of useful materials affords a wider range of possibilities than the various combinations of rubber and textile fibers. In rubber-textile combinations the cotton fiber is ordinarily used to impart tensile strength and to decrease the stretchiness of the product, while the attempt is made to retain at the same time as much resiliency as possible. Most of these combinations are of laminated construction, consisting of alternate layers of rubber compound and woven fabric, the physical properties being controlled by the construction of the fabric and the composition and cure of the rubber compound. Since cotton is usually more expensive on a volume basis than rubber, it is desirable to obtain the maximum tensile properties of the cotton fiber and to restrict its use as much as possible. That this is a difficult matter may be recalled when we compare the actual bursting strength of various mechanical goods with the so-called theoretical or calculated strength based on the additive strengths of the plied up fabrics in the fabricated article; it is at once apparent that only a small proportion of the fiber strength is effectively employed.
Laboratory Flexing Tests as an Aid in Investigating the Pneumatic Tire Carcass
Authors: Depew H. A. , Jones H. C.
Published: February 2011

TIRE tests, both service and test wheel methods, are generally used for carcass development, supplemented to a limited extent by laboratory tests, which include stress-strain tests on the compound and the cord, friction tests to measure the force necessary to pull the rubber compound from the cord, and pulley flexing tests. Owing to the cost and difficulty of reproduction of tire tests, it is desirable to use laboratory tests in so far as possible, although it will be impractical to eliminate tire tests as final checks before putting laboratory information into production and as a general method of attack for special problems in design. Among the important problems that lend themselves especially well to laboratory methods are: (1) Insulation of tire cord, including thickness of skim and spacing of the cord; and (2) rubber compounds (both before and after aging), including composition and state of cure. In choosing laboratory methods, it was decided to use flexing methods, with tension tests on the compound as an aid in judging state of cure. Friction tests were not made since they would be meaningless for indicating the bond between rubber and cotton when the cords are well separated in rubber.
3-Methyl-1,3-Pentadiene
Authors: Fisher Harry L. , Chittenden F. D.
Published: February 2011

3-Methyl-1,3-pentadiene can be prepared pure without difficulty. However, unlike butadiene, isoprene, piperylene, and 2,3-dimethyl-1,3-butadiene, it apparently does not polymerize to an elastic, resilient solid product, and therefore the polymerization of 1,3-dienes to rubber-like products does not depend solely on the presence of the vinyl group.
Studies in the Vulcanization of Rubber. III—Kinetics of Vulcanization of Rubber with Sulfur and Selenium
Authors: Blake John T.
Published: February 2011

A procedure for the determination of combined selenium in rubber has been evolved. The rate of combination of selenium and rubber has been ascertained under certain conditions and shown to follow a first-order equation. A minimum value for the molecular weight of rubber has been estimated. The formation of hard rubber under chosen experimental conditions has been put on a mathematical basis and has been shown to follow a second-order reaction. The soft- and hard-rubber reactions have been shown qualitatively to be successive reactions and the function of accelerators has been discussed. The theory explains the anomalous results obtained by previous investigators.
Effect of Pigmentation on the Work of Retraction of Rubber Compounds
Authors: Conover F. S.
Published: February 2011

THE reënforcement of rubber by pigments has been studied by a number of investigators (4, 5) by considering the effect of pigmentation on the extension stress-strain curves and on the areas enclosed between these curves and the elongation axes, which areas are a measure of the work of extension. (Figure 1) These investigations, in conjunction with other data, have developed two opinions concerning the mechanism of reënforcement; one (2), that reënforcement is caused by a bond between the rubber and the pigment particles; the other (3), that reënforcement is primarily a function of the particle size of the pigment and that the bond is of secondary importance. The work cited above shows that pigments exert different effects on work of extension, and it has consequently been assumed that they would have somewhat similar effects on work of retraction as measured by the areas enclosed between the retraction curves and the elongation axes. (Figure 1)
Various Ozonides of Rubber and the General Question of the Existence of Primary Ozonides
Authors: Pummerer R.
Published: February 2011

Harries was the first to make use of ozone cleavage at the carbon double bond of unsaturated compounds as an important method of research in organic chemistry. However, the formula (see PDF for diagram) of Harries, which is founded on its analogy with the products of other addition reactions, rests on scanty experimental data. One of the chief arguments against the formula is the absence of glycols as reaction products by the action of the most varied types of reducing agents. This latter fact, in conjunction with certain polymerization phenomena, led Staudinger to propose an isoozonide type of formula, in which the carbon chain has been opened, thus (see PDF for diagram) According to Staudinger, these isoozonides are formed very readily by transposition from primary or molozonides, and they are stable compounds. On the contrary, some molozonides are stabilized by polymerization. The constitution of butylene ozonide was proved synthetically by Rieche and Meister to be that of an isoozonide, and today the isoozonide formula has received general acceptance. In spite of these facts, some of the results of Harries, on which he based his original ozonide formula, remain unchallenged; for instance, the fact that when heated the ozonide of mesityl oxide reverts to mesityl oxide, and the fact that fumaric acid forms with ozone a loose compound from which ozone is liberated easily. In view of this, it appeared as if the Harries formula would really turn out to be the correct one, and that stable molozonides should exist.
Roentgenographic Investigations of Stretched Vulcanized Rubber
Authors: Iguchi Morihiro , Schossberger Fritz
Published: February 2011

The intensity of the amorphous ring of vulcanized rubber does not diminish uniformly in all parts of the ring with increase in the elongation, but diminishes from the equator towards the meridian. This effect indicates the existence of a hysteresis phenomenon.
Fatigue in Rubber. Part I
Authors: Cassie A. B. D. , Jones Maldwyn , Naunton W. J. S.
Published: February 2011

1. An apparatus is described for the measurement of the dynamic Young's modulus and associated frictional forces. 2. A modified apparatus is described for the measurement of the rigidity modulus and associated frictional forces. 3. The frictional loss of a rubber mixed with acetylene black is midway between the losses of rubbers mixed with gas and lamp black, respectively. 4. The frictional loss of rubber mixed with any form of carbon black falls with increase in temperature. 5. The moduli of rubbers containing gas and acetylene black decrease with increasing temperature, whereas those containing lamp black increase with increasing temperature similar to that of an unloaded rubber. 6. Frictional losses increase with cure, but the change becomes small around the optimum cure. 7. Antioxidants have a definite effect upon frictional loss quite apart from any effect due to alteration of degree of cure.
A Preliminary Study of the After-Effect or Drift in Rubber under Constant Load
Authors: Braun Milton L.
Published: February 2011

When a suitable weight is supported by suspension from a piece of rubber, as a stationer's band, the rubber may be stretched any amount up to several times its original length, but its new length is not constant; it increases with time. The increase in length with time is variously known as “after-effect, #x201D; “creep,” “drift,” “flow,” or “time-yield.” This phenomenon, which seems to have been very incompletely investigated, was probably first recognized by Dietzel in 1857. Kohlrausch in 1875 made an entensive study of both torsional and linear after-effect in metal, glass, and rubber. The load used by Kohlrausch on rubber were, however, exceedingly small, and the duration of drift was limited to one day. He came to the conclusion that drift in rubber followed a power law for the first sixty minutes. During the next decade Pulfrich slightly extended the work of Kohlrausch by experimentation on a red rubber tube, using elongations up to 150 per cent, with maximum observation time of 15 days. He concluded that the power law of Kohlrausch held for at least thirty minutes of drift. In 1903, Bouaase and Carrière observed the after-effect (in pure gum and sulfur cords of 4 mm. diameter and of specific gravity 0.984) under a great variety of experiments, and concluded that drift was to be expressed by an exponential or logarithmic law rather than by a power function. Both Phillips and Schwartz arrived at similar conclusions. More recently Ariano reported that the drift proceeded at a decreasing rate which finally assumed a constant value either finite or zero. Van Geel and Eymers found that for milled rubber the drift continued until the specimens broke, but that for rubber obtained by evaporation of latex all after-effect ceased within three minutes. Shacklock noted that creep took place for some hours and then reached a limit. Evidently more light needs to be cast on the probem of the drift effect in rubber. Two preliminary experiments on drift are herein considered; Part I on general trends, and Part II on more specific analysis of the effect as observed in one specimen.
Chemistry of Soft Rubber Vulcanization. V. Treatment of Dilute Rubber Cements with Sulfur Chloride
Authors: Garvey B. S.
Published: February 2011

PREVIOUS investigations (5, 6, 7, 8) indicated that vulcanization of rubber involves the establishment of a mechanical structure in the mass. This structure is apparently produced by changes in the hydrocarbon brought about by two chemical reactions: (a) addition of the vulcanizing agent and (b) a reaction of the hydrocarbon catalyzed by the vulcanizing agent. The experiments reported in this paper are concerned with the effect of sulfur chloride on the viscosity of dilute rubber cements under various conditions and with the solubilities of films obtained by evaporating cements treated with sulfur chloride. Consideration of the results has suggested a new interpretation of the nature of vulcanization. Experiments of a somewhat similar type have been reported by Bernstein (1, 2, 3), Fromandi (4), Kirchhof (10, 11), LeBlanc and Kröger (12, 13), Porritt (16), and Weber (18). In most of their investigations they used 100 per cent by weight of sulfur monochloride on the rubber. Since ordinary cold-cured articles contain about 1 per cent of sulfur monochloride, the effect of this small amount is most significant.
“Colloidal” Zinc Oxide
Authors: Curran H. A. , Dawson T. R.
Published: February 2011

Some ten years ago, when so-called “colloidal” zinc oxides were being introduced to the rubber manufacturing industry, two samples were investigated to determine their behavior in rubber compared with ordinary good quality zinc oxide used in rubber. According to accounts published at the time, “colloidal” zinc oxide possesses an average particle size just within the limit of resolution of high-power microscopes, and an average particle diameter of 0.15 micron. In rubber it has been claimed to impart superior reinforcement, higher tensile strength, greater resistance to abrasion, and enhanced activation of organic accelerators. In the following report, samples A and B represent two samples of the same grade of “colloidal” zinc oxide, and C a good grade of regular zinc oxide.
The Constitution of Inorganic Rubber
Authors: de Ficquelmont Armand Marie
Published: February 2011

There is a complete series of phosphonitrile chlorides of the general formula, (PNCl2)x, of which (PNCl2)3, (PNCl2)4, (PNCl2)5, (PNCl2)6, and (PNCl2)7 are already known. All these compounds have the remarkable property of changing rapidly around 350° C. into an amorphous substance which is insoluble and infusible, and whose mechanical properties are similar to those of rubber. It is, for this reason, generally known as inorganic rubber. According to the various authors who have studied this substance, the latter is a mixture composed solely of phosphonitrile chlorides of very high molecular weights. In the present paper, it will be shown that, contrary to this hypothesis, inorganic rubber, like all the gums obtained by Renaud at low temperatures, must contain, besides highly polymerized compounds which form a sort of network, lower members of the series which are confined in the meshes of this network. This assumption makes possible a simple interpretation of all the apparent phenomena of depolymerization of inorganic rubber which have been described up to the present time.