The Effect of Silent Electric Discharges on Rubber Solutions

1940 ◽  
Vol 13 (4) ◽  
pp. 831-848 ◽  
Author(s):  
Lothar Hock ◽  
Heinrich Leber
Keyword(s):  
Natural Rubber ◽  
Softening Temperature ◽  
Point Of View ◽  
Electric Discharges ◽  
Technical Point ◽  
Soluble Polymers ◽  
Synthetic Rubber ◽  
Molecular Sizes ◽  
Technical Sense ◽  
Insoluble Polymers

Abstract The object of the investigation was to synthesize higher molecular compounds from natural rubber and from synthetic rubber by means of a process involving exposure to silent electric discharges. With both natural rubber and synthetic rubber, it was found possible to bring about polymerization by this method and to obtain polymers of various molecular sizes, which could be separated into two principal types: (1) polymers which remained soluble in benzene, and (2) polymers with a highly developed network structure, which were insoluble in benzene and therefore could be separated from the soluble polymers. After purification and drying, the insoluble polymers were obtained as inelastic, nonplastic products, in the form of soft, crumbly flakes. On the contrary, the soluble polymers retained the plasticity and elasticity of the original rubber, and behaved like raw rubber in the technical sense as well. This latter fact was proved by preparing a few mixtures and vulcanizates from these polymers, and it is noteworthy that a vulcanizate prepared from polymerized Buna-85 more nearly resembled a corresponding vulcanizate from untreated natural rubber than it did a vulcanizate prepared from the original, untreated Buna-85. Of course more extensive development work would be necessary to obtain polymers with particularly desirable properties from a technical point of view, and to find out how to compound these new polymers, e. g., what types and percentages of fillers, accelerators, and percentages of sulfur to use. Only in this way can the technical importance of these products be judged, and can any uses to which they may be applied to advantage be determined. But whatever may be their importance, the increased molecular sizes of these polymers of natural rubber and of Buna-85 are accompanied by marked increases in softening temperature without sacrifice of their technically important advantages of plasticity, tackiness and solubility. To this extent a not unimportant goal from the technical point of view may be regarded as having already been attained.

Tack in Rubber

1964 ◽  
Vol 37 (5) ◽  
pp. 1178-1189 ◽  
Author(s):  
O. K. F. Bussemaker
Keyword(s):  
Natural Rubber ◽  
Theoretical Approach ◽  
Point Of View ◽  
Rubber Industry ◽  
Highly Active ◽  
Synthetic Rubber ◽  
The Usa ◽  
The Subject ◽  
The Difference ◽  
Definition Of

Abstract The expressions tack, tackiness, and stickiness have been in use since the beginning of the rubber industry. During the years their meaning has changed considerably. The first occasion where tackiness was mentioned was in the case of crude natural rubber. The surface of the rubber became tacky or sticky during storage. This phenomenon has been thoroughly discussed in the literature. As a general conclusion it was accepted that both oxidation and depolymerisation occurred. Three factors were reported to be the cause of these processes: light, traces of copper, and manganese. From our point of view we would call this effect stickiness, as we are only interested in the building tack of rubber. In the period when the only rubber was natural rubber and high loadings of highly active fillers were not generally used in compounds, building tack was no problem. Building tack was first mentioned in a publication by Griffith and Jones in 1928. They started their experiments by measuring tack in their search for methods to prevent cotton liners from sticking to unvulcanized rubber. One would have expected much work on the measurement and improvement of tack in Germany and Russia during the development of synthetic rubbers. However, this only proved to be the case in Russia. The first publication available was the translation of an article by Voyutskii and Margolina in 1957. From Voyutskii's work we were able to trace the first article in 1935 by Zhukov and Talmud, who studied the adhesive power of synthetic rubber. In the USA the first theoretical approach to the subject was by Josefowitz and Mark in 1942, who at that time did not realize the difference between stickiness and tack. This difference became clear when lack of tack became the big problem in the use of synthetic rubber. In many cases it was found that addition of resins and softeners gave a very sticky compound which had no building tack at all. The tack problem was first discussed at the ASTM symposium on the application of synthetic rubbers in 1944 by Juve who gave a definition of building tack. From that time, the problem has been studied regularly, especially from the practical side, to find ways and means to improve the building tack of synthetic rubbers.

Properties of Some Synthetic Rubbers

1943 ◽  
Vol 16 (4) ◽  
pp. 857-862
Author(s):  
L. B. Sebrell ◽  
R. P. Dinsmore
Keyword(s):  
Molecular Structure ◽  
Natural Rubber ◽  
Point Of View ◽  
General Point ◽  
Chain Molecules ◽  
X Ray ◽  
Synthetic Rubber ◽  
The Difference ◽  
Diffraction Patterns ◽  
Long Chain

Abstract X-RAY STRUCTURE OF SYNTHETIC RUBBER In presenting a series of x-ray diagrams of various types of synthetic rubber in comparison with natural rubber, in both the stretched and the unstretched condition, it is our purpose to bring out the fact that the molecular structure of synthetic rubbers is entirely different from that of natural rubber. It is proposed also to review briefly the theories which have been advanced, based on the x-ray analysis of rubber, to account for the elasticity of natural rubber, and to advance the possible reason for the difference shown by the x-ray diagrams of synthetic rubber. At the present time, from the most general point of view, the molecular structure of a rubberlike material is envisaged as a sort of brush-heap structure of entangled long chain molecules. x-Ray diffraction patterns show that, for some rubberlike materials, notable regularities of structure sometimes occur in the tangle of long-chain molecules. It is now realized that these regularities are not essential for rubberlike behavior. Nevertheless their observation and study is important because they afford a unique opportunity for studying the molecular structure of the chains and the molecular rearrangements which occur with the application of stress.

The Plasticization of Buna

1943 ◽  
Vol 16 (4) ◽  
pp. 866-880
Author(s):  
Harro Hagen
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Thermal Softening ◽  
Point Of View ◽  
Rubber Latex ◽  
Technical Point ◽  
Intended Application ◽  
The Poor ◽  
Optimum Formula

Abstract Recently oxidative thermal softening of Buna has come to the fore, a process which has been called “degradation”, a not too happily chosen term which suggests technical deterioration in quality. Properly speaking, there is loss in quality, just as there is considerable deterioration in quality when natural rubber latex is converted to dry rubber, a deterioration which is made still more extensive by mastication. Thus, while it is possible under laboratory conditions to make tread compounds having tensile strengths of 300–350 kg. per sq. cm. from natural rubber and latex compounds having tensile strengths of 450–500 kg. per sq. cm., the values obtainable with milled natural rubber are considerably lower. Despite this, one would not wish, except in the rarest instances, to dispense with the milling of natural rubber, since its processibility depends on the plasticization which is obtained by mastication. Thermal softening of Buna-S corresponds to the mastication of natural rubber. It has been possible to produce treads of unsoftened Buna-S with tensile strengths of 300 to 320 kg. per sq. cm. from compounds prepared in the laboratory, but these results cannot be obtained on factory mills because of the poor dispersion of fillers. With thermal softening, the tensile strengths of tread compounds made on laboratory mills would, to be sure, be somewhat lower, viz., 280–290 kg. per sq. cm. In mechanical compounds, the improved dispersion of fillers, compared with unsoftened Buna-S, would cause an increase in tensile strength. Oxidative softening is justified, not only from a processing and technical point of view, but above all because of the improvement in the finished product—provided, of course, that the degree of softening is suited to the intended application and that the optimum formula has been worked out. It would, therefore, be better to replace the derogatory word “degradation” by “oxidation” or “thermal softening”.

Vulcanization of Synthetic Rubbers

1951 ◽  
Vol 24 (3) ◽  
pp. 569-573 ◽  
Author(s):  
A. P. Pisarenko ◽  
P. A. Rebinder
Keyword(s):  
Natural Rubber ◽  
Physical Properties ◽  
Plastic Flow ◽  
Point Of View ◽  
Degree Of Saturation ◽  
Spatial Structures ◽  
Practical Point ◽  
Synthetic Rubber ◽  
Physico Chemical ◽  
Vulcanization Process

Abstract Although for a century since the discovery of the vulcanization of rubber by sulfur many investigators have worked in this field, the problem of vulcanization can still not be considered to be well understood, either from the theoretical or the practical point of view. The basis of the most widely accepted theory of vulcanization of rubber is the concept of bridges, according to which the vulcanizing agent, sulfur, unites the macromolecules of rubber into spatial chains by primary valences. The concept that such spatial structures are formed during the vulcanization process explains well the decrease in the degree of saturation of the rubber and the changes in its physical properties, e.g., decreases in solubility and plastic flow, and considerable increases in strength, modulus, and resilience. A number of experimentally established facts, however, can never be reconciled with the bridge theory of vulcanization, especially when the vulcanization of synthetic rubbers is investigated. As a consequence of this, a number of investigators in this country have pointed out the shortcomings of the bridge theory and the necessity of finding a better explanation of the physico-chemical and colloidal reactions which take place during the vulcanization of rubber. More recently Dogadkin and his associates have shown that even when an accelerator is added, which leads to an increase of the bridge sulfur content of the vulcanizate, the total amount remains insignificant, e.g., in the case of natural rubber it amounts to only 7–10 per cent and, in the case of synthetic rubber, to 2–6 per cent of the total bound sulfur.

Immunocytochemical methodology for the localization of neuronal antigens at the ultrastructural level

1990 ◽  
Vol 48 (3) ◽  
pp. 876-877
Author(s):  
Jorge Pecci Saavedra ◽  
Mark Connaughton ◽  
Juan José López ◽  
Alicia Brusco
Keyword(s):  
Spinal Cord ◽  
Substantia Nigra ◽  
Polyclonal Antibodies ◽  
Ultrastructural Level ◽  
Point Of View ◽  
Nerve Tissue ◽  
Tissue Fixation ◽  
Optimal Conditions ◽  
Interpeduncular Nucleus ◽  
Technical Point

The use of antibodies as labels for the localization of specific molecules in the nervous systan has been extensively applied in recent years. Both monoand polyclonal antibodies or antisera have been employed. The knowledge of the organization of neuronal connectivities, gliovascular relationships, glioneuronal relationships and other features of nerve tissue has greatly increased.A number of areas of the nervous systan have been analyzed in our laboratory, including the nuclei of the raphe system, the reticular formation, interpeduncular nucleus, substantia nigra, caudate nucleus, putamen, pallidum, spinal cord, pineal gland and others.From a technical point of view, a number of variables needed to be taken into account in order to obtain reliable and reproducible results. The design of the optimal conditions of tissue fixation, embedding, sectioning, dilution of antibodies, and adaptation of Sternberger PAP technique were sane of the parameters taken into account to optimize the results. It is critical that each step of the technique be defined for each particular case.

Localized Irrigation System for Thuja Orientalis in Intensive Culture

2018 ◽  
Vol 20 (1) ◽  
pp. 119-126
Author(s):  
Mădălina Stănescu ◽  
Constantin Buta ◽  
Geanina Mihai ◽  
Lucica Roșu
Keyword(s):  
Irrigation System ◽  
Ornamental Plants ◽  
Point Of View ◽  
First Year ◽  
Intensive Culture ◽  
Technical Point ◽  
Production Factors ◽  
Thuja Orientalis ◽  
Agricultural Farm

Abstract In order to increase the competitiveness of an agricultural holding through the efficient use of the production factors, the modernization of an agricultural farm was carried out by exending the existing greenhouse with at least 700m2 for the intensive cultivation of ornamental plants - Thuja Orientalis. The material is produced by initiating crops in pots, with seedlings grown in pots or transplanting them in pots right after the first year of the multiplication and growing them in containers, appropriate to their size, until reaching their full value. From a technical point of view, reaching the objective will also be possible through a localized irrigation system.

Bayesian Forcasting Model – 2020 Presidential Elections in the United States of America

2021 ◽  
Vol 704 (1) ◽  
pp. 91-104
Author(s):  
Maria Raczyńska
Keyword(s):  
United States ◽  
United States Of America ◽  
Presidential Elections ◽  
Bayesian Models ◽  
The United States ◽  
Point Of View ◽  
Forecasting Model ◽  
Bayesian Forecasting ◽  
Technical Point ◽  
Made In

The article describes and explains a prior centric Bayesian forecasting model for the 2020 US elections.The model is based on the The Economist forecasting project, but strongly differs from it. From the technical point of view, it uses R and Stan programming and Stan software. The article’s focus is on theoretical decisions made in the process of constructing the model and outcomes. It describes why Bayesian models are used and how they are used to predict US presidential elections.

Chlorinated Isoprene Rubbers in Adhesive Composites

2017 ◽  
Vol 44 (5) ◽  
pp. 25-28 ◽  
Author(s):  
A.A. Zuev ◽  
L.R. Lyusova ◽  
N.P. Boreiko
Keyword(s):  
Natural Rubber ◽  
Scientific Research ◽  
Scientific Research Institute ◽  
Physicomechanical Properties ◽  
Butadiene Rubber ◽  
Technological Factors ◽  
Nitrile Butadiene Rubber ◽  
Synthetic Rubber ◽  
Adhesive Materials ◽  
Isoprene Rubber

Now there is not a single area of industry that can do without adhesive elastomer materials. Composites based on synthetic rubbers comprise 75% of the total volume of adhesive materials produced, which is due to the combination of unique properties typical of the elastomer base of the adhesive. The base of many imported adhesives for the bonding of rubber to metal is chlorinated natural rubber. As an alternative, chlorinated synthetic isoprene rubber has been proposed, developed at the Scientific Research Institute for Synthetic Rubber in St Petersburg. The chlorinated isoprene rubber was compared with imported chlorinated natural rubber in adhesive composites, and the physicomechanical properties of mixes based on a blend of chlorinated rubber and nitrile butadiene rubber were investigated. The investigation was conducted on chlorinated natural rubber of grade Pergut S20, chlorinated isoprene rubber SKI-3, and nitrile butadiene rubbers of grades BNKS-28AMN and SKN-26S. The influence of the ratio of chlorinated rubber to nitrile butadiene rubber and the technological factors of mix preparation on the properties of films produced from them was established. It was shown that, in terms of the level of properties, home-produced chlorinated rubber can be used as the base for adhesives for hot bonding of rubber to metal instead of imported Pergut S20.

scholarly journals Sustainability and Competitiveness of Thailand’s Natural Rubber Industry in Times of Global Economic Flux

2017 ◽  
Vol 14 (1) ◽  
pp. 169
Author(s):  
Palapan Kampan
Keyword(s):  
Natural Rubber ◽  
Positive Relationship ◽  
New Technologies ◽  
Pearson Correlation ◽  
The United States ◽  
Bivariate Correlation ◽  
Synthetic Rubber ◽  
Reinforcing Factors ◽  
Strong Positive Relationship ◽  
Correlation Tests

This study assesses economic, legal, and environmental conditions that Thai rubber farmers face, and evaluates actions they can take to increase incomes. Statistical analyses determine relationships between prices of oil, natural and synthetic rubber. Pearson correlation tests found a strong positive relationship (r = 0.887) between the price of Brent crude and Thai ribbed smoked sheets, and a moderate positive relationship between price changes in Brent and synthetic rubber (r = 0.648). Regression analysis showed Brent oil price is a good predictor of natural rubber prices. Moderate to strong positive relationships were also found between natural rubber price and gross domestic product of Japan, China, and the United States. Criminal antitrust behavior in rubber industries appeared to interfere with normal pricing in rubber markets. No significant bivariate correlation was found between rainfall in Thailand and natural rubber price, production, or export although flooding and other environmental issues clearly affected rubber farms. A survey of options showed Thai rubber farmers can improve livelihoods best through collective purchase and use of new technologies, and by integrating into downstream supply chain industries. At very least, farmers are urged to abandon monocrop methods and supplement incomes with fruit, fish, livestock, or pigs. stment budget, 2) architectural Aesthetic, and 3) utilization. Additionally, background of the interviewees is one of reinforcing factors for decision on universal design investment.

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