Electrically Conducting Neoprene and Rubber

1942 ◽  
Vol 15 (1) ◽  
pp. 146-157 ◽  
Author(s):  
B. J. Habgood ◽  
J. R. S. Waring
Keyword(s):  
Volume Resistivity ◽  
Acetylene Black ◽  
Development Work ◽  
Electrically Conducting ◽  
Rubber Compounds ◽  
Transverse Volume ◽  
Transverse Conductivity ◽  
Set Up ◽  
Longitudinal Resistivity ◽  
Conducting Rubber

Abstract (1) The scattered references in the literature dealing with conducting rubber have been collected together. (2) A résumé of existing ideas on the mechanism of electrical conduction is given, from which certain lines of development work suggested themselves. (3) Electrically conducting Neoprene or rubber compounds based on acetylene black are anisotropic, an effect which is particularly pronounced after extrusion. (4) By the use of fine channel black, either alone or in addition to acetylene black, the transverse conductivity is improved, thus reducing the anisotropy. (5) A further improvement can be obtained by using highly plasticized Neoprene or rubber which reduces the shear during extrusion operations. In the case of Neoprene, zinc oxide is omitted from the mixings to prevent set-up. (6) Conducting tubes having a transverse volume resistivity of 300 ohms per cu. cm., and a longitudinal resistivity of 60 to 70 ohms per cu. cm. have been obtained, using a potential difference of 6 volts. (7) Provisional methods of testing conducting rubber are suggested.

Electrically Conducting Rubber

1949 ◽  
Vol 22 (2) ◽  
pp. 535-554
Author(s):  
K. A. Lane ◽  
E. R. Gardner
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Carbon Black ◽  
Advanced Degree ◽  
Static Electricity ◽  
Electrically Conducting ◽  
Rubber Compounds ◽  
Electrical Resistivities ◽  
Conveyor Belts ◽  
Conducting Rubber

Abstract In recent years the dangers and inconveniences arising from the presence of static electrical charges on rubber conveyor belts, rubber flooring, rubber-tired vehicles and the like, have aroused interest in the use of electrically conducting rubber as a means of minimizing the accumulation of static electricity. Conventional rubber compounds, which have electrical resistivities normally above 107 ohm-cm, and as high as 1014–1016 ohm-cm. for nonblack compositions, favor the accumulation of static charges. By using high loadings of channel black, the resistivity can be reduced considerably. If special types of carbon black are employed the resistivity can be reduced to a very low value ; in fact, the development of a compound with a resistivity of 1 ohm-cm. has been reported. A compound with a resistivity of about 10 ohm-cm., processible on ordinary factory-size rubber machinery, is described later in this paper. Rubber compounds with resistivities less than 107 ohm-cm. are generally grouped under the generic title of “electrically conducting rubbers”. The conduction of electricity through rubber-carbon black compositions is attributed to the ability of the carbon black to form chains of particles through the rubber. The formation of these chains depends on the particle size, crystal structure, and degree of dispersion of the black. The special types of black referred to above, termed conducting blacks, possess this ability for chain formation to an advanced degree. The work described below deals with the compounding of conducting rubbers, their application, and the methods used for testing. It appears under three main headings: measurement of resistivity; development of highly conducting rubber ; and development and testing of antistatic tires.

Effect of Various Types of Carbon Black on Certain Physical Properties of Rubber Compounds

1928 ◽  
Vol 1 (3) ◽  
pp. 458-464
Author(s):  
D. J. Beaver ◽  
T. P. Keller
Keyword(s):  
Carbon Black ◽  
Physical Properties ◽  
Acetone Extract ◽  
Acetylene Black ◽  
Direct Proportion ◽  
Rubber Compounds ◽  
Oil Adsorption ◽  
Iodine Adsorption ◽  
Standard Channel

Abstract The data presented herein show that in general the presence of oxygen on carbon black retards the rate of vulcanization in direct proportion to the amount of oxygen present and also decreases the maximum physical properties obtainable with a given amount of accelerator. The aging data show that the presence of this oxygen on the black increases the rate of aging as the amount of oxygen increases, but not in direct proportion to the per cent of this oxygen present. It can be concluded, therefore, that compounds which contain a small amount of oxygen, such as thermatomic, G black, or acetylene black, will give better aging stocks than compounds containing higher amounts of oxygen such as lampblack and standard channel blacks. No correlation could be found between the acetone extract, iodine adsorption, or oil adsorption, and the effect of these blacks on the rate of cure or aging.

Electromagnetic Flowmeter Primary Elements

1959 ◽  
Vol 81 (4) ◽  
pp. 660-666 ◽  
Author(s):  
V. P. Head
Keyword(s):  
Reynolds Number ◽  
Rate Equation ◽  
Electromagnetic Flowmeter ◽  
Flow Coefficient ◽  
Electrically Conducting ◽  
Volume Rate ◽  
Set Up

An obstructionless flowmeter for electrically conducting liquids is described. Tentative design and inspection criteria which have been found to provide accuracies of ±1/2 per cent, or as little as ±0.005 fps pipeline velocity, are set up. A practical threshold conductivity of meterable liquids is set at 20 micromhos per cm, though there is every reason to believe this will be drastically cut with further progress. Above this threshold, the flow coefficient in the volume-rate equation is shown by tests to be independent of the conductivity, of the Reynolds number, and of installation conditions.

Changes of Electrical Resistance of Rubbers Loaded with Carbon Black

1957 ◽  
Vol 30 (2) ◽  
pp. 572-583
Author(s):  
D. G. Marshall
Keyword(s):  
Experimental Investigation ◽  
Carbon Black ◽  
Natural Rubber ◽  
Electrical Resistance ◽  
Current Flow ◽  
Electrical Contact ◽  
Butyl Rubber ◽  
Initial Increase ◽  
Electrically Conducting ◽  
Conducting Rubber

Abstract Many workers have studied the changes in resistivity that occur on deforming rubbers loaded with carbon black. This paper describes three types of experimental investigation that do not seem to have received detailed study previously, and also a theory that explains the results qualitatively in terms of variations of contact resistances between carbon black particles. Firstly, the changes of resistance of vulcanized natural rubber, Butyl rubber, Neoprene, and Thiokol FA loaded with carbon black have been studied during cyclic deformations. Secondly, the initial increase of resistance during stretching testpieces of vulcanized natural rubber containing several loadings of different carbon blacks has been investigated. Finally, the changes of resistance with time that occur after stretching and releasing samples of electrically conducting rubber have been studied. The ingredients and preparation of the compounds used in experiments discussed in this paper are listed in the Appendix. The testpieces used in the following experiments were approximately 0.7 cm. wide, 0.1 cm. thick, and 7.0 cm. long. Electrical contact was established by means of brass strips bonded by molding into the ends of the samples, so that the direction of current flow was along the length of the pieces, and in the same direction as the extensions.

Dunlop Fatigue Test for Rubber Compounds

1942 ◽  
Vol 15 (4) ◽  
pp. 905-964
Author(s):  
V. E. Gough ◽  
D. Parkinson
Keyword(s):  
Fatigue Test ◽  
Subsequent Development ◽  
Development Work ◽  
Static Fatigue ◽  
Direct Compression ◽  
Test Machine ◽  
Steady Temperature ◽  
Early Form ◽  
Rubber Compounds ◽  
The One

Abstract This paper considers the effects produced inside a block of rubber subjected to repeated cycles of stress. Other types of fatigue, such as flex cracking or the phenomenon recently referred to by Cadwell, Merrill, Sloman and Yost as static fatigue, are not discussed. The fatigue test which will be described in the following pages has been used for a number of years in the Dunlop Rubber Company's laboratories. The test machine, like others which have been described by Martens, Vogt, Abbott, Depew and Snyder, Cooper, Havenhill and Macbride, Havenhill, Lessig, and Roelig, can be used for assessing heat development, the failure produced in the test-piece being then of the “blow-out” type, or it can be used to produce breakdown in specimens which have been stressed for prolonged periods at a moderately high, although steady temperature. The failure may then be considered to be one of fatigue and not one of thermal decomposition, although, as will be shown, the heating effect is one of the most important factors operating to produce failure. Among the test machines referred to above, the one described by Depew and Snyder is similar to the Dunlop machine, an early form of which was already in use for the purpose of evaluating heat generation in solid tire compounds when Depew and Snyder's paper was published in 1929. The present improved machine and technique are the result of several years of subsequent development work. The stressing conditions of the machine, which produce direct compression, are as simple as possible and give results which vary less and are more easily interpreted than those obtained when they are more complex, as, for example, when they introduce shear in addition to compression.

Alkylphenol Disulfide Polymer Accelerators and the Vulcanization of Isobutylene Based Elastomers

2008 ◽  
Vol 81 (4) ◽  
pp. 600-624 ◽  
Author(s):  
Brendan Rodgers ◽  
Scott Solis ◽  
Nitin Tambe ◽  
Bharat B. Sharma
Keyword(s):  
Double Bond ◽  
Natural Rubber ◽  
Butyl Rubber ◽  
Development Work ◽  
Cure Rate ◽  
Rubber Tire ◽  
Carbon Double Bond ◽  
Rubber Compounds ◽  
Starting Point ◽  
Further Development

Abstract Vulcanization of isobutylene/isoprene copolymer (butyl rubber) using sulfur and organic accelerators is facilitated by the presence of the carbon-carbon double bond in the copolymer isoprenyl unit. The low number of unsaturated monomer units, usually in the order of 2%, has traditionally necessitated use of ultra-fast accelerators such as tetramethyl thiuram disulfide (TMTD) or zinc dimethyldithiocarbamate (ZMDC). Use of such accelerators can result in formation of nitrosamines which may be undesirable. There are a number of alternatives to thiuram and dithiocarbamate cure systems such as use of xanthates and phosphate based accelerators. Alkylphenol disulfide based accelerators also enable attainment of favorable properties when used in butyl and halobutyl compounds. Use of alkylphenol disulfide accelerators in butyl rubber compounds can allow improvement in reversion resistance, adhesion to natural rubber tire casing compounds, and aged property retention. In bromobutyl compounds containing alkylphenol disulfide accelerators in binary (two accelerators) or tertiary (three accelerators) cure systems, adjustment in cure rate to meet specific requirements and aged property retention is possible. This, fifth in a series of studies on the vulcanization of isobutylene elastomers, explores the use of alkylphenol disulfide cure systems for vulcanization of both butyl and bromobutyl rubbers and is intended to provide a starting point for further development work.

The Effect of Pigment Particle Size on Some Physical Properties of Rubber Compounds

1936 ◽  
Vol 9 (4) ◽  
pp. 597-604
Author(s):  
C. E. Barnett
Keyword(s):  
Particle Size ◽  
Physical Properties ◽  
Liquid Flow ◽  
Rubber Compound ◽  
Small Particles ◽  
Size And Shape ◽  
Rubber Compounds ◽  
Large Particles ◽  
Set Up ◽  
Microscopic Set

Abstract The importance of flow in rubber on the reinforcing properties of pigmented systems has been emphasized by Park. He suggests that: (1) in the presence of a finely divided pigment, the flow which occurs when a piece of rubber is stretched takes place in the capillary spaces between the pigment particles; (2) some modification of the laws of liquid flow may govern the behavior of rubber with reference to pigments embedded in it, and (3) the forces causing increased stiffness in pigmented rubber compounds are similar to those causing increased resistance to flow of liquids iii tubes of capillary dimensions. Thus increasing fineness of subdivision and the resulting fineness of capillary spaces between the particles should be accompanied by an increase in reinforcing properties. It would be desirable to study the actual stresses around pigment particles in rubber under strain, but so far no suitable microscopic set-up has beem devised. A few years ago the writer, resorting to analogies, measured the strains and stresses around large particles with the assumption that the strains would be relatively the same with small particles. For this study, holes of the desired size and shape were cut in strips of calendered but uncured rubber and fitted with pieces of an uncured semihard rubber compound. After vulcanization squares were marked on the tensile sheets as shown in Fig. 1.

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