bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Packing of Rubber
Authors: Jones Fordyce 
Published: February 2011

Abstract
The practice of dusting smoked sheets with a suitable non-sticking powder has now been well tested for over three years, and during that period has proved its value. Large consumers of rubber in many sections of the industry find all that is necessary is to split the bales into suitable-sized pieces ready for compounding in large mills or internal mixers without close examination. It will be appreciated that it is somewhat difficult to make fine surgicals, inflatable or hot-water goods, toys or fancy goods, extruded or proofed goods from rubber without some form of examination. In the writer's section of the industry it is necessary that every sheet of rubber be carefully examined through the light so that it goes to the mill absolutely free from splinters, embedded bark, sand or other foreign matter, and adhered parts of any kind. The necessity of this is appreciated by all who make fine rubber ware successfully. The cost of “pulling” or separating blocks of rubber in this way is a high one; in fact, with gummy rubber, even when warm, the cost of “pulling” with labor at about 1s. 3d. an hour has been as high as ¾ d. per lb. Any way, the cost is always considerable, and as the remedy suggested herewith, and already proved in practice, costs so little and is so satisfactory it is surprising that it has not been adopted more widely.
The Components of Hevea Latex. Part II. Seasonal Variations in the Composition of Typical Seedling Latex
Authors: Roberts K. C. 
Published: February 2011

Abstract
1. Comparative analyses of fresh and ammoniated latices have been made, and the components investigated. 2. The changes effected by ammoniation are profound, and are far advanced in a period of eight weeks. Only the minor components, ammonium salt and ester, are inappreciably affected. 3. The fatty acid and the phosphate complexes of fresh latex undergo extensive hydrolysis within eight weeks of ammoniation, and part of the inorganic matter is firmly retained by the modified hydrocarbon. (See 5 below.) 4. The crude caoutchol of fresh latex is replaced by an increased amount of a viscous fluid which is thought to consist of a disaggregated portion of the hydrocarbon. Caoutchol itself, treated with dilute aqueous ammonia, becomes relatively insoluble, and is presumably retained on analysis by the remainder of the hydrocarbon. 5. The hydrocarbon of fresh latex is replaced by an ash-containing material which has a marked resistance to solvent action. This latter property is due not only to retention of the modified caoutchol (4 above), but also to modification (polymerization?) of the hydrocarbon itself by the action of the ammonia.
Contribution to the History of Latex
Authors: Eck Leo 
Published: February 2011

Abstract
The first move towards the direct use of latex was by Arnold Juliaans in 1780 when he published his “Dissertatio chemica de resina elastica cajennensi.” In this he proposed to use latex for the manufacture of medical instruments such as sounds, catheters, bougies, syringes, milk pumps, etc., either in the form of the original juice from the Hevea tree in America, where it flowed as latex from the trees, or else after transportation of this latex in the liquid state in suitable containers to Europe, where it could be converted into the desired rubber products. It is true that ten years before this Sir Joseph Banks, an English explorer and partner of Cook in his first voyage around the world, had brought back a bottle of latex in good condition, as a narrative by Grossart shows. Unfortunately however, the latex decomposed soon afterward, and Sir Joseph Banks offered in vain 50 gold louis at Lisbon for another bottle of latex. Grossart himself had received, towards the end of the eighteenth century, a half-bottle of milky juice which was sent by d'Arcet from Mauritius. Grossart left it for several winters in an unheated room, and after the very severe winter of 1788–1789 he found it broken. He was thus obliged to give up the experiments which he had in view.
Structure of Stretched Rubber
Authors: Clews C. J. B. , Schossberger F. 
Published: February 2011

Abstract
Investigations of the micellar structure of fiber substances have given rise to two theories. The older theory (Meyer and Mark, 1930; Mark, 1932; Siefriz, 1934; Meyer, 1930; and Nägeli, 1928) considers the micelles as separate crystallites, between which lie the intermicellar spaces. The micelles consist of “Hauptvalenzketten“ bound together along their length by homeopolar bonds and in the transverse direction by van der Waals' forces, the intermicellar binding being also attributed to van der Waals' forces. The original model suggested in work published by Meyer (1930) for cellulose depicts the micelles arranged like bricks in a wall (Fig. 1), and doubtless this is the simplest explanation of the x-ray results. But it is difficult to understand how such an arrangement can give a micellar structure its peculiar mechanical properties, and further how it is possible, when both inter- and intramicellar cohesion are attributed to the same type of force, to cause by swelling experiments an enlargement of the intermicellar spaces, while the “Hauptvalenzketten” remain unaffected.
Studies of Organic Accelerators. XVI. Part 4. Detection and Analysis of Organic Accelerators. Detection of Guanidine Accelerators in Vulcanized Rubber
Authors: Shimada Keichi 
Published: February 2011

Abstract
Rubber vulcanized with a thiuram accelerator such as tetramethylthiuram monosulfide or disulfide was tested with the author's cobalt oleate reagent after extraction with acetone and solution of the residue from the acetone extract in benzene, by testing the benzene extract of such vulcanized rubber. In all cases a characteristic yellowish green coloration of dithiocarbamate was observed. From this it is concluded that thiuram accelerators are transformed into dithiocarbamates during vulcanization. Accordingly, it is difficult to ascertain whether accelerators in vulcanized rubber were originally present as thiuram compounds, except when the rubber is undercured or when an excessive amount of accelerator is used. Here, too, the greater part is detected as dithiocarbamate. An experimental proof of the mechanism of acceleration is offered.
Estimation of the Stability of Rubber Solutions
Authors: Rachner Manfred 
Published: February 2011

Abstract
Various types of rubber products, such as seamless goods and rubberized fabrics, are prepared from rubber solutions and are vulcanized either by the hot or cold process. “Cold vulcanization” is effected either by sulfur chloride vapor or by very dilute solutions of sulfur chloride in solvents such as carbon disulfide, carbon tetrachloride, or benzine. “Hot vulcanization” is carried out by heating with sulfur, organic accelerators, and inorganic substances such as colloidal zinc oxide, to “activate” the accelerators. To safeguard against any unforeseen difficulties, it is necessary not only to ascertain how much tendency mixtures containing powerful accelerators have to vulcanize, but above all to determine for how long a time a solution remains stable, i. e., does not commence to vulcanize during ordinary use. To obtain an insight into the practical utility of a mixture, it is in general necessary merely to heat the mixture at 110° C. in a press. A mixture can be regarded without hesitation as satisfactory for practical use if it shows no indication of vulcanization after one hour at this temperature. On the other hand, products prepared from such a solution should as a rule vulcanize fully in 30 mm. at 125° C. or perhaps in 40–50 mm. at 110° C. In view of this, the practical utility of a mixture is judged by the tendency for incipient vulcanization to take place when the mixture is heated at 70° C. in a press. In the case of solutions of rubber mixtures which contain all ingredients milled into the rubber before the solution is prepared, incipient vulcanization is evident by gelation of the solution, i. e., a change from sol to gel. With mixtures of this kind, incipient vulcanization at 70° C. in a press may be accepted as a reasonable criterion, but in no case should it be regarded as a trustworthy indication of the stability of a solution up to the point of gelation, for the rate of vulcanization of the solution to the point of gel formation, and during gel formation itself, is influenced considerably by the constitution and the concentration of the solvent. The concentration of the solution and the degree of plasticity of the rubber mixture likewise influence gel formation. A test of the dry mixture at 70° C. in a press for incipient vulcanization does not take account of these factors.
The Proteins in Preserved Hevea Latex
Authors: Bondy C. , Freundlich H. 
Published: February 2011

Abstract
1. Two proteins were isolated from preserved Hevea latex. 2. The proteins were distinguished by their electrokinetic behavior and their solubilities in aqueous solutions and in alcohol. Protein A has an isoelectric point at pH 4.55; it is insoluble in distilled water and alcohol. Protein B has an iso-electric point at pH 3.9; it is soluble in pure water and strong (70 per cent) alcohol. 3. A comparison of the electrophoretic mobility of the latex particles as function of the pH with the corresponding curves of the proteins confirms the result of previous investigators that a coating of the rubber particles by proteins is decisive for their behavior. In a range of pH between 5.5 and 8 the curve of the latex particles is practically identical with that of protein A.
Stability of Ficus Elastica Latex
Authors: Daniel F. K. , Freundlich H. , Söllner K. 
Published: February 2011

Abstract
Thanks to the kind endeavors of E. Hoyle (Revertex, Ltd.) of Rengam Estate and to the support given by Mr. Simpson, manager of Rim Estate, we obtained a sample of 2.7 liters of Ficus elastica latex. The latex had been collected at Rim Estate, Malacca, on two successive days from about 10 trees which had not been tapped since 1912. Ammonia was added to the latex in such a quantity that about 700 milliequivalents per liter of free ammonia were present; methyl red was used as the indicator. The dry matter (T. S.) and dry rubber content (D. R. C.) estimations were T. S.=38.8 per cent, D. R. C.=36.5 per cent. Stability of Fresh and Preserved Latex In his report attached to the sample Mr. Hoyle writes: “… we used the ‘Herringbone’ tapping to obtain the latex as quickly as possible. Latex oozed on to the tapping cut freely at first, for a minute or two, but quickly thickened and became apparently half coagulated. Addition of ammonia solution to the tapping cuts did not help the flow appreciably, but addition of ammonia to the latex in the cups during dripping of the trees greatly reduced the viscosity of the latex and minimized the amount of coagulum to be strained off. Hevea brasiliensis trees which have been resting for some months, or which are freshly opened up, also yield only a small quantity of highly viscous latex at first. With the Ficus elastica trees, the cuts made on November 1, 1935, were reopened the next day, but the flow of the latex was then, if anything, worse than on the first day. …“This means that the latex is very unstable at the time it leaves the tree, and that this is so, regardless of the time interval between tappings. We confirmed statements in the literature that this latex when containing ammonia is very stable; when testing our sample seven weeks after tapping we found that it no longer had a tendency to be coagulated, either spontaneously or by the addition of other substances; on the contrary, it was very difficult to coagulate at all, the addition of electrolytes causing only microscopic aggregation and creaming. The cream readily redispersed on shaking.
The Fusion Curves of Rubber and Gutta-Percha
Authors: Meyer Kurt H. 
Published: February 2011

Abstract
It is already known that many rubber-like substances such as elastic sulfur and polyphosphornitryl chloride show crystal interferences when stretched, and that these interferences disappear again when the tension is removed. This shows that the melting point is increased by traction, and von Susich actually determined roentgenographically the relation between the melting point and deformation and thus obtained a “fusion curve.” This phenomenon can be explained by means of the kinetic theory of the elasticity of rubber. According to this theory, the stress set up in rubber when stretched depends on the fact that heat motion tends to restore to the statistically favorable, crooked, and hence shorter form, the primary valence chains which have been extended by traction and thus are in a statistically less probable position and form. For, as a result of free rotation, it is possible to have many curved forms but only one maximum elongated form; the thermodynamic probability β, and on account of the relation: S=R ln β, the entropy S as well, are consequently greater in the unstretched than in the stretched state.
A New Transformation Product of Rubber
Authors: Kratky O. , Philipp H. , Posnansky K. W. , Schossberger F. 
Published: February 2011

Abstract
As investigations carried out long ago have shown, rubber reduces silver nitrate. On the contrary, experiments with specially purified unvulcanized rubber films have shown that the rubber itself is not the reducing agent, but rather impurities in the non-rubber components; in fact, it is even possible to incorporate large quantities (up to about 20 per cent by weight) of silver nitrate in rubber. In the experiments to be described, rubber films were prepared by drying latex which had been electrodecanted repeatedly; these films were swollen in a solution of silver nitrate in a mixture of water and acetone, and were then dried. The films obtained in this way were noteworthy for their high tensile strength compared with the original films, and were studied by means of x-rays. Instead of the diffused ring which appears ordinarily when unstretched rubber is examined, the x-ray diagram of this new product showed a series of sharp rings (see Fig. 1a) which did not correspond to any of those of inorganic silver compounds. When the product was stretched, the diagram changed, without appreciable alteration of the glancing angle, into that shown in Fig. 1b and finally into that shown in Fig. 1c. Figure 1c also shows a fiber diagram different from that of ordinary stretched rubber.
Colloidal Structure of Rubber in Solution. Effect of Precipitants
Authors: Gehman S. D. , Field J. E. 
Published: February 2011

Abstract
RUBBER solutions are somewhat unstable and their colloidal structure, usually characterized by viscosity, can be influenced by a large number of agencies such as light, oxygen, and small amounts of various reagents. The colloidal changes caused by the addition to a rubber solution of typical nonsolvents or precipitants, such as alcohol or acetone, are distinguished by the fact that they are reversible. If the precipitant is removed, the original solution can be recovered. The reversible colloidal changes, which result eventually in precipitation, were studied in the work here reported as a means for acquiring knowledge of the colloidal structure of rubber in solution. As in a former article (8) an effort is made to utilize comparatively recent advances in the general theory of the liquid state (3, 5, 9). Previous publications dealing with the effects of nonsolvents on rubber solutions have been predominantly of technical interest and limited almost exclusively to viscosity measurements. LeBlanc and Kröger (13), Messenger and Porritt (2, 16), Kawamura and Tanaka (11) described the viscosity changes which ensue upon the addition of various nonsolvents to rubber solutions. Whitby (25) classified the reagents which can be used to affect the viscosity of rubber solutions. In a later publication (23) he discussed an interesting experiment during which incipient precipitation was observed with the ultramicroscope. Lens (14) reported the results of a few measurements of the effect of alcohols on the relative intensity of the light transversely scattered by benzene solutions of rubber. Ford (6) and Fabritziev, Buiko, and Pakhomova (4) studied the modification of technical rubber cements by the use of nonsolvents. The colloidal effects of precipitants on solutions of high polymers such as polystyrene have been observed and are of interest in connection with this work (18, 21, 22, 26).
Contributions to the Analysis of Rubber. III. Determination of Copper in Raw Rubber, in Mixtures, and in Fillers
Authors: Dekker P. 
Published: February 2011

Abstract
It is already well known that copper compounds have an extremely harmful effect on rubber articles. Since, however, very small quantities of copper are always present in fillers, in fact, in compounding ingredients in general and even in ordinary plantation rubber itself, it is not possible to manufacture a rubber article which is free of copper. In view of this, one must be content in each case with keeping the copper content within a certain allowable limit. However, it has been found that not only is the quantity of copper of decisive importance, but that still other factors play a part in the harmful effects brought about by the copper. Attention has been called repeatedly in the literature to the fact that copper compounds which are injurious are those which dissolve in the rubber mixture. Nevertheless, it is certain that the harmful effects of copper depend not only on solubility but also on other factors. But since so little is known about this problem, nothing can be done for the time being except to regard any copper which may be found as injurious. In the Netherlands Government Rubber Institute the permissible quantity of copper in rubber articles has been set at 0.001 per cent. Although with this percentage harmlessness is not guaranteed, it may still be expected that, with such small percentages of copper compounds, aging is not affected unfavorably. The present work is concerned chiefly with methods for determining copper.
Analysis of Organic Accelerators
Authors: Robinson J. G. 
Published: February 2011

Abstract
From the viewpoint of the works chemist, a knowledge of the qualitative and quantitative analysis of organic accelerators is desirable as a valuable supplement to a knowledge of their technical applications. Confusion or uncertainty as to the composition of a particular package of material may occur even in the best regulated factories; this may well prove to be an organic accelerator, and the chemist is expected to be able to give a decision in all such cases. Again, many accelerators are still sold under trade names and a knowledge of their chemical composition enables the chemist to use them in a more intelligent way, especially in predicting their vulcanizing characteristics in conjunction with other accelerators, and also in disposing of off-grade compounds by incorporation of a percentage in standard mixings. Although the uniformity of qualtity reached by present-day suppliers of accelerators is of a high order, most works chemists wish as a matter of principle to institute some form of acceptance control. Tests in rubber are obviously desirable, but they take considerable time and require expensive plant; analytical methods, where available, enable some form of control to be exercised in cases where tests in rubber are impracticable owing to shortage of time or other considerations.
Behavior of Antioxidants in Rubber Stocks Containing Copper
Authors: Jones Paul C. , Craig David 
Published: February 2011

Abstract
(1) Deterioration accelerated by copper in a high-grade tread stock, a low-grade tread stock, a high zinc oxide bus-tube stock, and a pure-gum stock has been found to be effectively retarded by the use of suitable antioxidants. (2) Secondary aromatic amines have been found to be much more effective than other antioxidants, in tread stocks, for retarding deterioration due to copper. (3) The degree of protection afforded to rubber compounds containing copper by the use of certain antioxidants, notably secondary aromatic amines, is sufficiently high to make their addition of practical importance.
Early Stages of Oxidation in Rubber. A Quantitative Application of the Pyrrole Test
Authors: Temple J. W. , Cadwell Sidney M. , Mead Morris W. 
Published: February 2011

Abstract
The foregoing will illustrate some of the applications which have been made with the test as developed by the authors. Since the above work was completed, van Rossem and Dekker (5) have published their very significant paper on extraction of rubber with benzene—alcoholic potash mixture. Both methods apply to rubber at the same stage of its life, and it should be interesting to compare results from the same sample. In general it may seem that their method is of somewhat higher accuracy, while the pyrrole test requires less time and labor and is more informative as to the actual processes of oxidation.
Laboratory Evaluation of Flex-Cracking Resistance
Authors: Cooper L. V. 
Published: February 2011

Abstract
A machine has been designed for laboratory evaluation of the flex-cracking resistance of any stock from which a dumb-bell strip may be cut. The conditions under which the stock is tested may be varied at the will of the operator. The results obtained on this machine on tread and sidewall stocks have always evaluated the flex-cracking resistance of stocks in the same order that actual road tests have. MANY factors are involved in the proper compounding of rubber stock. In tread compounding wear resistance is the major consideration, but other factors closely approach it in importance. Among these is the ability to withstand repeated flexing without cracking. Flex cracking produces an unsightly appearance which conveys the idea of inherent weakness in the tire, and also, if the flex cracking becomes very pronounced, the tire may fail from carcass break at that point. A satisfactory tire must not, flex-crack. Flex-cracking resistance is dependent on two things—the stock itself and the stress under which it is working. The design of the tire—that is, size and shape of the buttons, the size and position of the side ribs, and the amount of lettering on the side—regulates the working stress under which the sidewall and tread are operating. This accounts for the fact that two tires made by different companies may be different in flex-cracking resistance although of very similar or even identical compounding.
Phenomena of the Mechanical Deformation of Rubber
Authors: Mark H. , Valko E. 
Published: February 2011

Abstract
It is only during recent years that it has become possible by the use of new technic to detect molecular phenomena produced in the mechanical deformation of substances. As far as metallic substances are concerned, and crystalline substances in particular, the problem has already been solved for the most part. On the other hand, in spite of considerable progress during recent years the study of the deformation of organic substances and of fibers in particular, in which group rubber is included, has not yet been carried on. The mechanical properties of a crystalline system vary according to whether there is a single crystal or an aggregate of crystals. However, in both cases the extensibility of the products originates in a displacement of parallel layers, i. e., a sliding of the parts of the crystal along definite crystalline planes, this phenomenon of sliding being irreversible in these substances. In fact, in these cases the reversible part of the elongation is very weak, and amounts to only a few thousandths of the entire phenomenon. In brief, the phenomena of hardening brought about by deformation (sometimes observable) are due to disturbances of the regular lattice. In particular, the displacement of the atom and the change from its normal position can cause the appearance of irregularities on the surface of sliding.