bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Plasticization of Rubber. I. Structural Changes in Thermally Plasticized Rubber
Authors: Farberov M. I. , Margolina Yu 
Published: February 2011

Abstract
1. The results of the experiments give a more or less complete picture of the relative changes in rubber brought about by mechanical and thermal plasticization, and show that there is an analogy between the two effects. 2. The fundamental factor in thermal plasticization is oxygen (for a given set of thermal conditions), whereby a definite numerical relation exists between the plasticization effect and the oxygen concentration. In the experiments described, the quantity of oxygen absorbed by rubber did not exceed 0.55 per cent at the maximum temperature and time of treatment (170° C. for 120 minutes). Thermal plasticization in a medium devoid of oxygen (in carbon dioxide, nitrogen, and ammonia) proceeds very feebly. 3. In treatment at reduced pressure (in vacuo), and consequently with a diminished oxygen content, the higher the vacuum, i. e., the lower the concentration of oxygen, the less was the plasticization obtained. 4. The effect of temperature in thermal plasticization was evident in the acceleration of the reaction between rubber and oxygen. The most effective temperature was in the interval of 150° and 170° C. 5. For an equal plasticity, the internal structure of rubber was preserved to a greater degree after thermal treatment than after mechanical plasticization, judged by the structural viscosity, n, and the magnitude, Q. 6. It was observed that rubber treated at high temperature (170° C.) in carbon dioxide, nitrogen, and ammonia lost to a considerable degree its ability to dissolve in common rubber solvents.
Thermal Plasticization of Rubber. II. Technical Characteristics of Softened Rubber
Authors: Farberov M. I. , Susliakov A. V. 
Published: February 2011

Abstract
1. The method of thermal plasticization makes it possible to prepare rubbers of widely varying but regulated degrees of plasticity. 2. The use of thermally plasticized rubber gives a considerable saving of power in the production of stock. In our experiments the saving of power amounted to 15–50 per cent, depending upon the proportion of rubber in the stock and on the required plasticity. The greater the proportion of rubber, and the more plastic the rubber required for the stock in question, the greater will be the saving in changing from ordinary masticated rubber to thermoplasticized rubber. Based on equal plasticities, the saving is due essentially to the elimination of the process of mechanical mastication. 3. Mechanical properties of vulcanizates made from thermoplasticized rubber, both before and after aging, are in no way inferior to those of vulcanizates made from ordinary masticated rubber, if the plasticities of the rubbers are equal. 4. Thermoplasticized rubber has a smaller calender-grain effect than standard masticated rubber. 5. Thermoplasticized rubber is distinguished by a considerably smaller water absorbing capacity (about one-half) than ordinary masticated rubber.
Investigations of Dispersing Agents and Stabilizing Agents for Latex Mixtures, and the Behavior of Latex Mixtures When Stored
Authors: Bächle Otto 
Published: February 2011

Abstract
The great sensitivity to mechanical as well as to chemical influences which is possessed by latex, in common with all hydrophobic colloids, leads to immediate difficulties in the preparation of its mixtures. The ingredients, which in most cases are insoluble in water, must first be finely ground and then dispersed in water before being added to the latex mixture. Good dispersion is effected only by the use of high efficiency mechanical dispersion apparatus (ball mill, pigment grinding mill, etc.) and at the same time by the use of a suitable dispersing agent. Moreover, since latex mixtures may have to be stored for a long time, and since premature coagulation may take place during the preparation of such mixtures by the ingredients added or by mechanical influences, and later by incipient vulcanization, it is necessary to stabilize these latex mixtures in practice so that they can be handled safely. Much work has already been done on the stabilization of latex and latex mixtures, as a result of which a great number of products are recommended and used today. A certain stabilizing action is obtained by the addition of water, a greater stabilizing action by aqueous solutions of alkalies. Furthermore, soaps and soap-like compounds are used, e. g., casein is in general a good medium. A few special products are offered today by the chemical industry.
Raman Spectrum of Rubber and Some Related Hydrocarbons
Authors: Gehman S. D. , Osterhof H. J. 
Published: February 2011

Abstract
A Raman line spectrum has been secured for rubber and balata by using clear gels of the purified hydrocarbons. It was not found possible to eliminate the background entirely. The most intense frequency for both rubber and balata is the same, 1670 cm.−1, ascribed to the double bond. Comparison of the frequencies for rubber and balata with those of trimethylethylene, myrcene, isoprene, and limonene shows that the primary linkages in rubber are very similar to those in trimethylethylene, thus supporting the view that the rubber molecule consists of a long chain of isopentene units. Differences in the spectra require an explanation, however. The spectrum of balata shows differences from that of rubber such as might be expected from a cis-trans relationship. The spectrum of myrcene is largely a superposition of the isoprene and trimethylethylene spectra.
Fundamental Studies on the Attributes of Organic Accelerators. XI. Peculiarity of Some Accelerators toward Rubber Sols
Authors: Shimada Keichi 
Published: February 2011

Abstract
Experiments lead to a revision of former views regarding the action of heat and of Group C accelerators on rubber solutions. The changes in the viscosities of dilute rubber solutions by heating or by the addition of Group C accelerators are attributed to a destruction of the remaining micelles, i. e., a disaggregation and subsequent depolymerization of the rubber molecules thus formed and those already present.
Reinforcement and Stearic Acid
Authors: Barron Harry 
Published: February 2011

Abstract
(1) Addition of stearic acid does not increase reinforcement of carbon black mixes to an appreciable extent; however, the work of retraction is considerably augmented, and the hysteresis loss is reduced. (2) The action is two-fold; free stearic acid lubricates, thereby reducing internal friction, while dissolved stearic acid reduces interfacial tension, thereby increasing wetting or true reinforcement. (3) Addition of more than 2 per cent of stearic acid lowers reinforcement, since the lubrication effect decreases that portion of reinforcement due to internal friction. (4) “Blooming” of stearic acid occurs because it decreases surface tension of rubber, and consequently concentrates in the surface. (5) Removal of stearic acid causes complete disappearance of reinforcement, as measured by work of extention to rupture.
Studies on the Acetone Extraction of Raw Rubber. VII. The Time of Acetone Extraction of Raw Rubber and the Saponification Value of the Acetone Extract and Residue
Authors: Endô Hidemaro 
Published: February 2011

Abstract
During acetone extraction of pale crepe, the free acids and saponifiable matter were extracted almost completely in 1 or 2 hours. The saponification value (A) had a tendency to decrease rapidly and to reach a minimum after 12 hours (in non-continuous extraction) or after 16 hours (in continuous extraction). The cause of the decrease of the saponification value (A) from the commencement of extraction up to the time mentioned is thought to be due to a gradual increase in the amount of extracted non-acidic compounds and unsaponifiable matter with increasing time of extraction, and to the neutralization of acids by other compounds, as by esterification. After reaching the minimum point, the saponification value (A) had a tendency to increase gradually. This increase is thought to be due to (1) a gradual increase of ester extracted, (2) the formation of acids by oxidation, and (3) the formation of free acids by decompositions of esters, though the last factor does not increase materially the saponification value. The change of saponification value of the acetone extract with increasing time of extraction is not due to any change in the type of compounds gradually extracted, but to a change in the acetone extract in the acetone solution during extraction. This is in agreement with the acid value. It was observed in a previous paper (III) that almost all of the free acids contained in pale crepe were extracted by acetone in 1 hour. But by extraction for 1 or 2 hours, a small portion of the saponifiable matter still remain unextracted. This remaining part could not be extracted even by prolonged extraction. It is believed, therefore, that the free fatty acids are dissolved in the saponifiable matter, and that the latter are dissolved in the rubber hydrocarbon. As the acetone extract is very labile, so far as the change of acetone extract is concerned, the acetone extract, whether it be dried or left in solution, should not be stored for too long a time. The results obtained by such long extraction by acetone as multiples of ten hours, as used by Whitby and Winn (J. Soc. Chem. Ind., 41, 336T (1923)), are thought to be quite unreliable.
Determination of Free Sulfur by Titration
Authors: Faĭnberg B. 
Published: February 2011

Abstract
In a recent article on the “Iodometric Method of Determination of Free Sulfur” by Bolotnikov and Gurova (J. Rubber Ind. U. S. S. R., 10, 61 (1933); Rubber Chem. and Technology, 8, 87 (1935)), the authors described a rapid method for determining free sulfur in rubber without a preliminary extraction.
Effect of Oxygen Absorbers in Rubber
Authors: Somerville A. A. 
Published: February 2011

Abstract
In this discussion of flex-cracking, its causes, and a means of controlling it, the theory that oxidation of the rubber is the main factor involved has been used as a foundation. No attempt has been made to prove chemically that oxidation of the rubber actually takes place. This would be difficult, since flex-cracked rubber does not necessarily show the ordinary signs of deterioration, but the work of Neal and Northam (4) has indicated that oxygen plays a part. The facts that oxygen absorbers definitely retard flex-cracking and also that the more strongly they are able to absorb oxygen, the greater is their retarding effect, would be difficult to explain on any other basis. The mechanism of the reaction, however, is obscure and is further complicated by the fact that the oxygen absorbers develop their full effect only in the presence of a catalytic antioxidant. As a working hypothesis it may be assumed that the oxygen absorber removes dissolved or absorbed oxygen within the rubber before and during vulcanization, while the antioxidant protects the rubber surface against atmospheric oxygen during service. It is realized that this hypothesis does not explain every fact connected with the use of oxygen absorbers to complete satisfaction and will doubtless be subject to change or modification as practical experience with these agents accumulates. In the meantime it is believed that a practical commercial means of greatly retarding the flex-cracking tendency of rubber goods has been developed.
Hydrazines as Rubber Softeners
Authors: Williams I. , Smith C. C. 
Published: February 2011

Abstract
THE process of softening rubber has received much less study than its importance deserves. Since the method of softening rubber by mastication was devised by Hancock, the greatest advances have been in the introduction of machines of greater mechanical efficiency and greater capacity. Prior to 1920 the effect of such variables as temperature was little understood. Long and inefficient periods of milling at high temperatures were common. In case milling did not produce the required plasticity, recourse was had to the addition of oils, resins, and other soft materials sometimes in considerable amounts. Such conditions have not yet entirely disappeared. Various methods have recently been proposed for plasticizing rubber in a more uniform manner and with less power consumption. Worthington and Hyde (24) softened rubber by heating it in a nonoxidizing atmosphere. Bradley and Ferrettie (1) concluded that the rubber should be water-soaked before it is heated and should be kept wet during the process. Tuley (21) patented the process of softening rubber by the addition of lead dioxide during the period of mastication, and Gerke (7) used a mixture of lead dioxide with an organic acid anhydride. Cruikshank (4) proposed the use of solvents containing alcohols of high molecular weight or sulfonated petroleum products as mastication assistants. According to Martin (10) the addition of nitrites to the latex before coagulation produces rubber of superior plasticity. Rubber softened by heating in an oxidizing atmosphere according to the method of Unger and Schidrowitz (22) has recently become a commercial product.
Hard Rubber. Its Carbon and Hydrogen Content
Authors: Fisher Harry L. , Schubert Y. 
Published: February 2011

Abstract
IN THE course of a study of vulcanization it became necessary to compare the ratios of carbon, hydrogen, and sulfur in hard rubber. A search of the literature revealed no analyses for carbon and hydrogen, although many analyses for sulfur in hard rubber have been recorded. Combustion analyses were therefore made on several samples of hard rubber, and the data are recorded here. The saturation of the double bonds in the rubber hydrocarbon with sulfur should give a compound, (C 5H8S)x, which contains 32.02 per cent of combined sulfur, and some of the recorded results agree with this figure. Since it is also possible to obtain products having greater amounts of combined sulfur than that called for by the theory of addition alone, some of the sulfur must consist of sulfur of substitution (7). It is theoretically possible that substitution and addition of sulfur can go on simultaneously; as the result of these two reactions, it may happen that the total sulfur in combination will equal the theoretical amount required by addition alone. In such a case there would be some free double bonds, but attempts to determine free double bonds in several samples by the Kemp-Wijs method (5) were unsuccessful.
X-Ray Spectrography of Polymers and in Particular Those Having a Rubber-like Extensibility
Authors: Katz J. R. 
Published: February 2011

Abstract
For many years Staudinger defended the theory that polymers have—in the simplest ease—a long chain form of molecules, in which a certain small unit repeats itself regularly along the chain, the units being united by primary valencies. His arguments were not, however, at the beginning of 1927, sufficiently convincing. The decisive argument was forthcoming shortly afterwards by the application of x-ray spectrography. I would like to begin this article by bringing a few personal memories about this development. At the meeting of the Naturforscherversammlung in Innsbruck in September, 1924, I first heard him defend this theory, especially for the ease of polyoxymethylenes, but also for some other cases. Neither I myself nor some others to whom I spoke were convinced by his very interesting exposition. His conception seemed possible, but, many of us thought, not proved. And the whole subject did not yet look attractive to many of us. At the meeting of the Naturforscherversammlung in Düsseldorf in September, 1926, where a symposium on high molecular weight substances was held, he again defended this theory. In 1926, the interest in the subject had already increased a good deal, as is clearly shown by the fact that a symposium on the subject had been arranged. Yet, Staudinger's conceptions did not seem to many of us really convincing, nor was the decisive value which x-ray spectrography could have for the subject yet understood at this meeting. Under these circumstances there can be little doubt that the priority of the idea of the long chain molecules for polymers is chiefly due to Staudinger.
Chloroprene Synthetic Rubber (Sovprene)
Authors: Klebanskiĭ A. L. , Tzyurikh L. G. , Dolgopol'ski I. M. 
Published: February 2011

Abstract
1. A method is described for the continuous polymerization of acetylene at low temperatures in a dilute aqueous solution of the catalyst, CuCl.NH4Cl. Monovinylacetylene is obtained as the chief product of the reaction, with a 75–80 per cent yield, based on the acetylene entering into the reaction, and 25–30 per cent of trimers and higher polymers of acetylene as by-products. The conversion of acetylene by a single passage of the gas is 40 per cent. The yield, based on the acetylene, is nearly 100 per cent. 2. Data on the optimum amount of the catalyst are compiled, and the principal factors which affect the process of polymerization of acetylene with the formation of monovinylacetylene as the chief product are shown. 3. The problem of the mechanism of the polymerization of acetylene is discussed. 4. A method of separation and collection of the reaction products by absorption in solvents is described. 5. A method for the discontinuous synthesis of chloroprene without excess pressure is described. 6. A procedure for the continuous production of chloroprene from pure monovinylacetylene and its mixture with acetylene is described. 7. The conditions of the polymerization of chloroprene to α-polymer are described, with particular reference to the conditions which inhibit the formation of rapidly aging and hardening polymers. The latter are considered as balata-like products. 8. A process of polymerization in solvents, with formation only of the α-polymer is described.
The Internal Heating of Ebonite during Vulcanization
Authors: Daynes H. A. 
Published: February 2011

Abstract
It is known that the reaction between rubber and sulfur to form ebonite is strongly exothermic, and under certain conditions may cause a marked internal rise of temperature during vulcanization. This heating is sufficient in many cases to accelerate the rate of vulcanization of the center of the mass to an important extent, so that the degree of vulcanization of the center differs from that of the surface, the product thus being non-uniform in physical properties. In more severe cases the temperature may rise sufficiently to cause decomposition, evolution of gas and porosity, or even violent explosion. This internal heating is favored by a high temperature of vulcanization, by great thickness of the mass to be vulcanized, by the addition of accelerators of vulcanization, and by the omission from the mixing of inert compounding ingredients, which act as diluents. It is, perhaps, not so commonly known that the heating is greater in an open steam cure, owing to the lower rate of dissipation of heat from the surface, though this factor may have been one of those leading to the common adoption of the water immersion method of cure. In technical practice the inconvenience of this phenomenon is avoided as far as possible by a control of the factors mentioned, including such devices as the inclusion of semi-vulcanized ebonite dust or crumb, building-up from semi-vulcanized sheets, “stepped” or rising cures, or, where possible, by designing the object so as to facilitate conduction of heat from the center by means of recesses or metal inserts.
Internal Protective Coatings for Latex Containers. Investigations of Internal Protective Coatings for Latex Containers and Their Value in Minimizing Discoloration in Preserved Latex
Authors: Rhodes Edgar , Sekar K. C. 
Published: February 2011

Abstract
In a previous publication (cf. J. Rubber Res. Inst. Malaya, 5, 176 (1934); Rubber Chem. and Tech., 7, 433(1934) the present authors have discussed fully the causes of discoloration in preserved latex and have shown that the iron drum which is in common use as a latex-shipment vessel is in itself a predisposing factor in the discoloration of latex. Users do not however look with favor on the substitution of a non-metallic container for the steel drum, and since suitable alternative metallic containers are prohibitive in cost, there remains little alternative but to endeavor, by the internal application of some protective medium, to reduce to a minimum the objectionable effects of the iron drum on its contents. Since discoloration is due to the formation of dark-colored colloidal and amorphous sulfides of iron, a satisfactory drum-coating medium should prevent contact of the latex with the iron of the drum, and also if possible react with any sulfur compounds which may be liberated in the latex, to form sulfides which are either white in color or so nearly white that when present in latex they are not detectable by the eye. It is essential that the coating should not be so brittle as to crack or flake away from the metal when drums are roughly handled in transit. If flaking occurs, serious contamination of the latex may result. The requirement is a tough, elastic film which will adhere well to the metal and which will not be appreciably affected by long contact with ammoniated latex, except in so far as it may combine with sulfur compounds to produce a white product.
A Simplified Extrusion Plastometer for Unvulcanized Rubber
Authors: Dillon J. H. 
Published: February 2011

Abstract
An extrusion plastometer operating at rates of shear comparable with those existing in rubber tubing machines has been described previously. This plastometer was not designed to be a routine testing instrument, but rather was intended for use in the determination of the value of a high speed extrusion test for the factory control of rubber stocks. The plastometer served satisfactorily in the capacity of a research instrument, and has for some time been in constant use as a physical testing instrument where great rapidity of operation is not essential. The results obtained with this plastometer were found to correlate with tubing machine behavior. It was also found that the extrusion plastometer results agreed better with factory experience with various types of masticated rubber than did the Williams plastometer results. It was learned by experience with the extrusion plastometer, when used as a physical testing instrument, that its results agreed closely with calender behavior. In many cases, it was found that the extrusion plastometer results did not correlate with the Williams plastometer results and that, in general, the extrusion plastometer appeared to be much more sensitive than the Williams plastometer. The next step after establishing the value of the high speed extrusion test was to design an extrusion plastometer suitable for routine control testing. Such an instrument must be rugged in construction, rapid and simple in operation, and must yield precise results. The extrusion plastometer, which is described in this paper, was designed to fulfill these requirements and at the same time to give the same type of test results as those given by the original experimental plastometer.
An Impact Cutting Test for Tire Tread Stocks
Authors: Dillon J. H. 
Published: February 2011

Abstract
The impact cutting device described in this paper is recommended for testing the cutting resistance of tread stocks because of its simplicity and the accuracy with which its results agree with road test results. The fact that the device was designed on semi-quantitative theoretical grounds gives some additional confidence in its results. It is possible that other cutting devices, designed with no regard to theory whatsoever, might operate as well as the impact device. However, it is felt that, since most laboratory tests on rubber stocks are necessarily largely empirical, it is well to attempt to design a testing machine which will operate in the ranges of the variables found in service.