Experiments on Synthetic Rubbers of the Butadiene Type. II. Mechanical and Electrical Properties of Buna Ebonites

1944 ◽  
Vol 17 (3) ◽  
pp. 719-730
Author(s):  
J. R. Scott
Keyword(s):  
Electrical Properties ◽  
Natural Rubber ◽  
Breaking Strength ◽  
Present Report ◽  
Butadiene Rubber ◽  
Type Ii ◽  
Normal Amount ◽  
Mechanical And Electrical Properties ◽  
Plastic Yield ◽  
Synthetic Rubber

Abstract The experiments described here were designed to examine the properties of ebonites made from various kinds of Buna synthetic rubber, including Buna-85, Buna-115, Buna-S and Buna-N. All Bunas are said to form ebonites by vulcanization with the normal amount of sulfur, Buna-85 and Buna-115 giving the best products. The resulting ebonites are stated to have much higher plastic yield temperatures than ordinary ebonite, figures quoted ranging from 100° to 175° C by the Martens test, compared with 70° to 90° C for natural-rubber ebonites. It may be added that Russian butadiene rubber likewise is claimed to give ebonites with much higher yield temperatures, namely, up to 160° C by a Vicat needle test, than ordinary ebonites, which give about 93° C. On the other hand, Buna ebonites are relatively brittle. The electrical properties of these ebonites are said to be good, and in this connection it should be noted that soft vulcanizates made from Buna-85 and Buna-115 have lower power factors than those made from natural rubber. Buna ebonites are more resistant than ordinary ebonite to attack by chemicals and to the swelling action of liquids such as benzene and nitrobenzene. The present report deals with certain properties of Buna ebonites, viz., plastic yield, cross-breaking strength, impact strength, radio-frequency permittivity and power factor.

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.

Properties of Ebonite. XXX. Influence on Properties of Ebonite of the Type of Raw Rubber Used, with Special Reference to Purified Rubbers

1949 ◽  
Vol 22 (1) ◽  
pp. 232-244
Author(s):  
D. G. Fisher ◽  
J. R. Scott ◽  
W. H. Willott
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Natural Rubber ◽  
Power Factor ◽  
Breakdown Strength ◽  
Practical Importance ◽  
Water Soluble ◽  
Plastic Yield ◽  
Latex Rubber

Abstract Tests have been made on unloaded ebonites prepared from ordinary commercial types of natural rubber, special (deproteinized) rubbers having reduced contents of protein and(or) other water-absorbent substances, and a whole-latex rubber containing relatively large percentages of these substances, to determine to what extent these substances influence the electrical properties of the ebonite and, hence, whether any technically useful improvement can be effected by using specially prepared rubbers. Permittivity and power factor at 106 cycles per second, but particularly power factor, are somewhat improved by using the special rubbers, so that the dielectric loss can be reduced by about 30 per cent. In addition, the increase in dielectric loss caused by exposure to high humidity or by a rise of temperature is in general lessened by the use of these rubbers. Similar, though smaller, improvements in the properties of the ebonite are obtained by washing ordinary commercial rubber (smoked sheet). Although a definite improvement in dielectric loss is obtained, it does not seem probable that purification of natural rubber would lead to ebonites with dielectric properties approaching those of polystyrene, for instance. It seems unlikely that even complete elimination of the water-absorbent impurities would reduce the dielectric loss by more than 50 per cent; the rubber-sulfur compound itself thus appears to be responsible for a fair proportion of the loss normally observed. The large percentages of water-soluble substances present in whole-latex rubber increase the permittivity and especially the power factor of the ebonite made from it. The dielectric properties of ebonite are related, though not closely, to its water-absorbing capacity and that of the raw rubber used, low absorption being in general accompanied by low dielectric loss and reduced sensitiveness to humidity variations. There is only a rough parallelism between the water absorptions of raw rubbers and the corresponding ebonites. Probable reasons for this are indicated. It is concluded that water absorption tests on raw rubber form a useful, though only approximate, guide to its value for making electrical ebonite; electrical tests on the ebonite must be the final criterion. Apart from very impure whole-latex rubber, no correlation can be traced between the inorganic content (ash) of ebonite and its electrical properties. The probable reason for this is indicated. There is evidence that the dielectric loss of ebonite may increase with the passage of time. In view of its obvious theoretical and practical importance, this phenomenon requires further study. No technically useful advantage as regards breakdown strength, volume resistivity, surface resistivity, or stability to light, by the use of the special rubbers, is evident in the present work. The plastic yield characteristics of ebonite are not appreciably altered by using special rubbers. Estimations of uncombined sulfur and also plastic yield tests show that one of the deproteinized rubbers vulcanizes more rapidly than the rest, which differ little among themselves.

Influence of critical carbon nanotube loading on mechanical and electrical properties of epoxidized natural rubber nanocomposites

2018 ◽  
Vol 66 ◽  
pp. 122-136 ◽  
Author(s):  
Apinya Krainoi ◽  
Claudia Kummerlöwe ◽  
Yeampon Nakaramontri ◽  
Norbert Vennemann ◽  
Skulrat Pichaiyut ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Electrical Properties ◽  
Natural Rubber ◽  
Epoxidized Natural Rubber ◽  
Mechanical And Electrical Properties ◽  
Rubber Nanocomposites

Properties of Ebonite. XXXVII. Electrical Properties of Synthetic Rubber Ebonites

1949 ◽  
Vol 22 (4) ◽  
pp. 1084-1091
Author(s):  
D. G. Fisher ◽  
L. Mullins ◽  
J. R. Scott
Keyword(s):  
Natural Rubber ◽  
Power Factor ◽  
Power Loss ◽  
Ionic Conduction ◽  
Effect Of Temperature ◽  
Plastic Yield ◽  
Styrene Copolymers ◽  
Synthetic Rubber ◽  
High Dielectric ◽  
Butadiene Styrene

Abstract Experiments were carried out to explore the possibility of making good electrical ebonites from various types of synthetic rubber. The ebonites produced were tested for permittivity and power factor over wide ranges of temperature and frequency. Thioplasts (Thiokols AZ and FA) apparently do not produce hard ebonitelike vulcanizates by the normal procedure. Neoprenes (GN and I) give ebonites, but with such high dielectric power loss as to be unsuitable for use as high-frequency dielectrics; moreover, if the mix contains zinc oxide, the ebonite has a very hygroscopic and therefore electrically unsatisfactory surface. Butadiene copolymers containing polar groups (butadiene-acrylonitrile types and Thiokol RD) give ebonites with high power loss, hence are not suitable for making high-grade electrical ebonites. Polybutadiene (Buna-85) and butadiene-styrene copolymers (GR-S, Hycar-EP, Buna-S) are much nearer to natural rubber as far as the radio-frequency (100 to 2,500 kc. per sec.) power loss of their ebonites is concerned. The GR-S ebonite examined was not so good as natural rubber at room temperature, but was superior above about 50° C. Buna-85 and Hycar-EP were superior to natural rubber over the whole temperature range; indeed, the high-styrene copolymers, as represented by Hycar-EP and Buna-SS, appear to be the best type of synthetic rubber for making ebonite with low power loss, especially at high frequencies and temperatures. The effects of changing temperature and frequency on permittivity and power factor are discussed. Attention is drawn to the big effect of temperature on power factor; this was less with polybutadiene and butadiene-styrene ebonites than with natural rubber ebonite, in keeping with the greater heat resistance of the former as judged by plastic yield tests. Comparison of the effects of rising temperature and decreasing frequency shows that these produce broadly similar effects on power factor, as would be expected on theoretical grounds, but that rising temperature superposes a second effect (an increase), presumably due to increased ionic conduction.

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