Analysis of Resistivity in a Rubber Compound

1991 ◽  
Vol 64 (4) ◽  
pp. 501-509 ◽  
Author(s):  
D. Roig Fernández ◽  
A. J. Marzocca
Keyword(s):  
Electrical Resistivity ◽  
Carbon Black ◽  
Probability Model ◽  
Rapid Test ◽  
Rubber Matrix ◽  
Rubber Compound ◽  
Internal Factors ◽  
Tire Industry ◽  
Degree Of Dispersion ◽  
Electrical Conduction Mechanisms

Abstract In the tire industry, good dispersion of carbon black in the rubber matrix is very important to obtain optimum mechanical properties of the compound. Usually, this dispersion can be classified in macrodispersion (for particles bigger than 10 μm) and microdispersion (for those smaller than 10 μm). It is known that good microdispersion enables better fatigue resistance and wear. If it is desired to control the degree of dispersion of uncured compounds during the different processes in the factory, it would be necessary to have a simple and rapid test to do it. An appropriate method to detect different degrees of dispersion is based on the measurement of the electrical resistivity of the rubber compound with dc or ac. In recent years, different factors that affect the resistivity of the compounds were studied in several research programs. The internal factors include structure, size, and dispersion of carbon-black particles, the presence of other reinforcement (silica), and the polymer class. Other factors studied are external: mixing level, pressure, temperature, aging, and contact resistance. Boonstra showed that resistivity depends on the degree of dispersion of carbon black. In his paper, resistivity data are compared with the dispersion levels according to the Cabot rating with good correlation. Furthermore, there are several electrical conduction mechanisms that are proposed in the literature to explain experimental data. It is the purpose of this paper to present an improvement of the Boonstra device for the measurement of electrical resistivity of uncured compounds. The influence of temperature, pressure, aging, carbon black level, and time on the mill roll over the electrical resistivity were also studied. Finally, the results were analyzed by a probability model.

Electrical Resistivity of Carbon-Black-Loaded Rubbers

1990 ◽  
Vol 63 (3) ◽  
pp. 451-471 ◽  
Author(s):  
Tejraj M. Aminabhavi ◽  
Patrick E. Cassidy ◽  
Corley M. Thompson
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Carbon Black ◽  
High Surface ◽  
Self Regulation ◽  
Physicochemical Characteristics ◽  
Rubber Matrix ◽  
High Resistivity ◽  
High Electrical Resistivity ◽  
Materials Research

Abstract Uses are growing for rubbers with varying levels of resistivity. High electrical resistivity is very much essential in wire and cable insulation applications. Low levels of resistivity are needed for electrostatic discharge in phonograph records and many medical, industrial, and military products and for semiconductive cable compounds. The level of resistivity depends upon the number of contacts or near contacts between conductive particles in the rubber matrix. Loading level is obviously a major determinant in addition to physicochemical characteristics of the black. In the latter regard, the highly conductive grades are characterized by small particle size, high structure, high surface porosity, and low volatile content. One would, therefore, seek the reverse of those factors for high-resistivity rubbers. One of the goals of materials research now is to create new materials with physicomechanical properties tailored to a particular application and to understand the physical processes which determine the end properties. In this review, an attempt has been made to discuss the electrical properties of carbon-black-loaded rubber composites, a class of materials which covers the range from insulators to conductors. The carbon-black-loaded rubbers are formed by dispersing carbon black into the rubber. The compounding is done by adding the carbon black to the rubber, mixing at temperatures above Tg and subjecting the mixtures to high shears until a uniform blend is obtained. The carbon-black particles may be as small as 14 nm in diameter or as large as 300 nm, and they may be individually dispersed or agglomerated in micron-sized clusters. Morphology of the rubber has a profound effect on its electrical properties. High electrically resistive rubbers are becoming increasingly important. Their wide array of applications include antistatic products, shielding materials, insulating membranes, resistors, etc. In the vicinity of the crystalline transition region the rubber shows a dramatic resistivity increase which can be utilized for self-regulation processes. Compounds suitable for such various applications differ appreciably in the nature of their components and composition depending on the specific performance required.

Dispersion of Carbon Black in Rubber: Revised Calculation Procedure

1961 ◽  
Vol 34 (4) ◽  
pp. 1134-1140 ◽  
Author(s):  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Microscopic Examination ◽  
Quantitative Comparison ◽  
Rubber Compound ◽  
Visual Appearance ◽  
Degree Of Dispersion ◽  
Quantitative Calculation ◽  
Glass Knife ◽  
Qualitative Estimation ◽  
Reinforcing Filler

Abstract Carbon black, the most important reinforcing filler for rubber, must be well dispersed if it is to function effectively. The state of dispersion of the carbon black can be studied effectively by microscopic examination of a thin (2µ) section of the rubber compound, using transmitted light, as described by Tidmus and Parkinson. Under the microscope, agglomerates of undispersed carbon black are visible. These agglomerates, which may range in size up to 100µ or even larger, are sectioned more or less cleanly by the glass knife, and appear as black or dark brown islands in a light brown field. While this method was originally proposed for qualitative estimation of the degree of dispersion, a quantitative calculation was subsequently developed by Leigh-Dugmore, by means of which the percentage of carbon black dispersed below a certain size was calculated. This calculation has been helpful in permitting a quantitative comparison of stocks of widely different visual appearance. As experience has accumulated with the Leigh-Dugmore method, some puzzling observations have been made. Frequently, the modulus level of a stock of a given dispersion was found to be higher than the proportionate modulus of a stock of 100% dispersion. Furthermore, stocks have occasionally been prepared with a measured dispersion rating of less than zero (see below). It thus seemed worthwhile to re-examine the Leigh-Dugmore calculation.

Resistivity of Unvulcanized Compounds of Rubber and Carbon Black

1977 ◽  
Vol 50 (1) ◽  
pp. 194-210 ◽  
Author(s):  
B. B. Boonstra
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
Carbon Black ◽  
Coefficient Of Variation ◽  
Absolute Temperature ◽  
Good Precision ◽  
Rubber Compound ◽  
Rubber Compounds ◽  
Rapid Monitoring ◽  
Coaxial Probe

Abstract 1. A coaxial probe has been developed which allows measuring electrical resistivity of uncured carbon black-rubber compounds with good precision (mean coefficient of variation 4%). 2. For a given compound the resistivity correlates well with the standard dispersion rating and thus can be used for rapid monitoring of dispersion at various stages of processing. 3. Resistivity may also serve as a check on the loading and type of black in a rubber compound. 4. The resistivity of uncured compounds is higher by a factor of 2–10 than the corresponding vulcanizate value. 5. The logarithm of the resistivity appears to be a linear function of the reciprocal of the absolute temperature. The apparent activation energy of conductance for SBR compounds is 14.7–29.3 kJ/mol, the higher values being found for the better dispersions. The activation energies of EPDM compounds were found to be approximately 50% higher than those of SBR.

Carbon Black Dispersion and Reinforcement

1952 ◽  
Vol 25 (4) ◽  
pp. 843-857 ◽  
Author(s):  
E. M. Dannenberg
Keyword(s):  
Electrical Resistivity ◽  
Carbon Black ◽  
Aggregate Size ◽  
Surface Oxidation ◽  
Light Transmittance ◽  
Rubber Matrix ◽  
Carbon Blacks ◽  
Improved Technique ◽  
High Degree ◽  
Carbon Black Dispersion

Abstract Different mixing conditions were employed to obtain vulcanizates, varying only in degree of carbon black dispersion, with natural and synthetic rubbers, using a single sample of a commercial grade HAF black. Light transmittance measurements on dilute solutions of dissolved unvulcanized stocks prepared by an improved technique were used to evaluate the size of carbon black aggregates in cold GR-S and natural rubber stocks. Electron micrographs of films show the high degree of carbon black aggregation, even after prolonged mixing. A limiting degree of dispersion or a minimum aggregate size is obtained very rapidly as mixing is increased. Black incorporation and dispersion appear to take place simultaneously; a high degree of abrasion reinforcement was noted in most rubbers with mixing (less than 75 seconds) barely sufficient to incorporate the black. Carbon blacks in general respond rapidly to mixing, and the chainlike aggregates characteristic of reinforcing carbon blacks observed under the electron microscope are practically unchanged after mixing with rubber. Dispersion of carbon blacks during mixing depends on the packing and coherence of their agglomerates resulting from such factors as surface oxidation and extent of mechanical bulk densification. There is some evidence that oil-type furnace blacks disperse more easily than channel blacks. A major cause of the disappointing abrasion reinforcement with most noncarbon pigments possessing extreme fineness may be the tendency for excessively strong aggregate binding and resulting large aggregates in rubber. A striking rise in electrical resistivity was observed as the amount of mixing was increased. As the size of the aggregates did not change, the higher electrical resistivity cannot be explained by assuming better dispersion and breakdown of conductive carbon paths. Increased mixing might provide better distribution of the carbon aggregates in in the rubber matrix without change in size of aggregates.

Numerical Modeling of the Electrical Resistivity of Carbon Black Filled Rubber

2008 ◽  
Vol 575-578 ◽  
pp. 930-934 ◽  
Author(s):  
Zhi Min Xie ◽  
Young Jin Yum ◽  
Han Gi Min ◽  
Jin Hyug Son
Keyword(s):  
Electrical Resistivity ◽  
Carbon Black ◽  
Volume Fraction ◽  
Rubber Matrix ◽  
Aggregate Distribution ◽  
Filled Rubber ◽  
Random Arrangement ◽  
Tunneling Conduction ◽  
Width Distribution

Carbon black (CB) filled rubber is microscopically heterogeneous although homogeneous on a macroscopic scale. CB particles are generally in the form of aggregates, which form the CB network in the rubber matrix. In this work, the junction width between CB aggregates is modeled as a contact resistor and the tunneling conduction mechanism is taken into account, and then an infinite circuit consisting of numerous contact resistors, interconnected with each other, is proposed to simulate the CB network in filled rubber. Prior to determination of the junction width distribution, CB spheres equivalent to CB aggregates in volume is assumed in a specifically random arrangement. Thus, the effect of CB aggregate distribution on the electrical resistivity is discussed. It is found that, for CB (N330) filled natural rubber with volume fraction of 27.5%, the simulated electrical resistivity at a standard deviation of 0.1 mean junction width is in good agreement with the experimental data available in the literature.

NMR of Reinforced Elastomers: Part II. The Influence of Carbon Black Dispersion

1982 ◽  
Vol 55 (4) ◽  
pp. 1095-1107 ◽  
Author(s):  
G. E. Wardell ◽  
V. J. McBrierty ◽  
V. Marsland
Keyword(s):  
Carbon Black ◽  
Rubber Compound ◽  
Average Quality ◽  
Degree Of Dispersion ◽  
Multiple Sampling ◽  
Polymer Formation ◽  
Specific Formulation ◽  
Carbon Black Dispersion

Abstract 1. NMR measurements can provide a fast and efficient monitor of the incorporation and dispersion of carbon black in a reinforced rubber compound. Tests can be carried out at all stages of processing, including masterbatch stock. 2. The technique provides a determination of the fraction of polymer which is bonded to the surface of the carbon black particles. Within a specific formulation, there is reasonably good correlation between the percentage of bonded polymer, determined by NMR, and the degree of dispersion of carbon black determined optically. 3. Bonded polymer formation is sensitive to carbon black type and to the nature of the host elastomer. In comparison of different formulations, there is no correlation between the fraction of bonded polymer and the dispersion of the black. However, carbon black-rubber attachments are fundamental to the phenomenon of reinforcement and, in this respect, NMR bonded-polymer measurements can provide a valuable probe for the investigation of reinforcement. 4. Samples taken from large internal mixers (capacity 200 kg) show that compound inhomogeneity on a gross scale necessitates multiple sampling in order to give an assessment of the average quality of the mix, irrespective of the technique used.

Polymer composites as sensing materials for liquid organic solvents – preliminary results

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Stanislaw Frackowiak ◽  
Monika Maciejewska ◽  
Andrzej Szczurek ◽  
Marek Kozlowski
Keyword(s):  
Electrical Resistivity ◽  
Carbon Black ◽  
Polymer Composites ◽  
Percolation Theory ◽  
Liquid Mixtures ◽  
Organic Liquids ◽  
Volumetric Fraction ◽  
Factors Influencing ◽  
Benzene Toluene ◽  
Main Factors

AbstractCarbon black-filled polymer composites were investigated as sensing materials for organic liquids. Polypropylene and polystyrene which were selected as matrices and various amounts of carbon black were considered as the main factors influencing sensitivity of the composites in view of the percolation theory. Disposable filaments were produced of these materials. Change in their electrical resistivity was measured upon immersion in benzene, toluene, xylene, ethylbenzene and their mixtures. It has been found that studied materials were sensitive to the composition of liquid mixtures of organic solvent. Relationships between the filament response and volumetric fraction of the components were presented. The studied materials have shown promising sensing properties, which suggest their applicability for identification and quantification of multicomponent organic liquids.

scholarly journals Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1085
Author(s):  
Patricia Castaño-Rivera ◽  
Isabel Calle-Holguín ◽  
Johanna Castaño ◽  
Gustavo Cabrera-Barjas ◽  
Karen Galvez-Garrido ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
High Performance ◽  
Rubber Matrix ◽  
Butadiene Rubber ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rubber Blends ◽  
Ft Ir ◽  
Chloroprene Rubber

Organoclay nanoparticles (Cloisite® C10A, Cloisite® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

Wet compounding with pyrolytic carbon black from waste tyre for manufacture of new tyre – A mini review

2021 ◽  
pp. 0734242X2110047
Author(s):  
Junqing Xu ◽  
Jiaxue Yu ◽  
Wenzhi He ◽  
Juwen Huang ◽  
Junshi Xu ◽  
...  
Keyword(s):  
Carbon Black ◽  
Pyrolytic Carbon ◽  
Research Progress ◽  
Rubber Matrix ◽  
Innovative Technology ◽  
Nano Materials ◽  
Natural Rubber Composites ◽  
Waste Tyres ◽  
Dry Mixing ◽  
Waste Tyre

Pyrolysis offers a more focused alternative to waste tyres treatment. Pyrolytic carbon black (CBp), the main product of waste tyre pyrolysis, and its modified species can be applied to tyre manufacturing realizing its high-value utilization. Modified pyrolytic carbon black/natural rubber composites prepared by a wet compounding (WC) and latex mixing process have become an innovative technology route for waste tyre remanufacturing. The main properties and applications of CBp reported in recent years are reviewed, and the main difficulties affecting its participation in tyre recycling are pointed out. The research progress of using WC technology to replace dry mixing manufacturing of new tyres is summarized. Through literature data and comparative studies, this paper points out that the characteristic of high ash content can be well utilized if CBp is applied to tyre manufacturing. This mini-review proposes a new method for high-value utilization of CBp. The composite mixing of CBp and carbon nano-materials under wet conditions is conducive to the realization of their good dispersion in the rubber matrix. This provides a new idea for customer resource integration and connection of industry development between the tyre production industry and waste tyre disposal management.

scholarly journals Electromagnetic Interference Shielding and Physical-Mechanical Characteristics of Rubber Composites Filled with Manganese-Zinc Ferrite and Carbon Black

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 616
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Klaudia Hložeková ◽  
Rastislav Dosoudil ◽  
Marek Gořalík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Zinc Ferrite ◽  
Mechanical Characteristics ◽  
Hybrid Composites ◽  
Rubber Matrix ◽  
Butadiene Rubber ◽  
Frequency Range ◽  
Manganese Zinc ◽  
Manganese Zinc Ferrite

In the present work, composite materials were prepared by incorporation of manganese-zinc ferrite, carbon black and combination of ferrite and carbon black into acrylonitrile-butadiene rubber (NBR). For cross-linking of composites, standard sulfur-based curing system was applied. The main goal was to investigate the influence of the fillers on the physical-mechanical properties of composites. Then, the electromagnetic absorption shielding ability was investigated in the frequency range 1 MHz–3 GHz. The results revealed that composites filled with ferrite provide sufficient absorption shielding performance in the tested frequency range. On the other hand, ferrite behaves as an inactive filler and deteriorates the physical-mechanical characteristics of composites. Carbon black reinforces the rubber matrix and contributes to the improvement of physical-mechanical properties. However, composites filled with carbon black are not able to absorb electromagnetic radiation in the given frequency range. Finally, the combination of carbon black and ferrite resulted in the modification of both physical-mechanical characteristics and absorption shielding ability of hybrid composites.

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