Carbon Black Morphology in Rubber

1977 ◽  
Vol 50 (4) ◽  
pp. 842-862 ◽  
Author(s):  
G. C. McDonald ◽  
W. M. Hess
Keyword(s):  
Image Analysis ◽  
Carbon Black ◽  
Size Distribution ◽  
Surface Area ◽  
Surface Activity ◽  
Unit Size ◽  
Wear Rates ◽  
Rubber Compounds ◽  
Activity Structure ◽  
Black Surface

Abstract Electron microscope image analysis of carbon blacks in specific rubber compounds has greatly expanded the range of useful applications for studies of this type. This dispersed carbon-gel procedure has improved the sampling and test precision at operating speeds that are now reasonably comparable to the simple colloidal procedures for characterizing carbon black. Improved models have been developed for deriving black surface area and intraunit occlusion capacity. The EM image analysis approach has been useful in applying certain principles of reinforcement theory, as well as in explaining rubber property differences that are attributable to carbon black variables. Studies on hysteresis at constant strain (E″) have indicated that the important black variables, in diminishing order of significance, are loading, structure (intraunit occlusion and anisometry), unit size, unit size distribution, and surface activity. For hysteresis at constant energy (resilience), the most important black variables appear to be black loading, unit size, unit size distribution, surface activity, and structure. In terms of tread wear resistance (moderate wear rates with SBR-BR), a somewhat different pattern of carbon black variables is apparent. At constant loading, the most important black properties appear to be specific surface area, surface activity, structure, and unit size distribution. At any given tread wear-surface area level, hysteresis can be lowered by broadening the unit size distribution and increasing the surface activity of the black.

Carbon-Black-Elastomer Interaction II: Effects of Carbon Black Surface Activity and Loading

1993 ◽  
Vol 66 (5) ◽  
pp. 772-805 ◽  
Author(s):  
J. A. Ayala ◽  
W. M. Hess ◽  
G. A. Joyce ◽  
F. D. Kistler
Keyword(s):  
Surface Energy ◽  
Carbon Black ◽  
Surface Activity ◽  
Volume Fraction ◽  
Heat Treating ◽  
Inert Atmosphere ◽  
Morphological Properties ◽  
Rubber Compounds ◽  
Carbon Black Surface ◽  
Black Surface

Abstract Carbon black morphology, surface activity and loading have been varied systematically to study the effects on an SBR formulation. The surface activity of five commercial grades of carbon black was varied by heat treating the standard grade samples at 1100°C and 1500°C in an inert atmosphere. Measurements on carbon black-elastomer interaction were based on a parameter I, defined elsewhere. The parameter I exhibited the previously reported correlation with known indicators of the surface activity of carbon blacks. The heats of adsorption by inverse gas chromatography at infinite dilution have been found useful as a measure of the carbon-black surface energy related to rubber interaction. These measurements have been employed in conjunction with carbon-black morphology and loading to develop a surface-area-modified and a surface energy-modified effective volume fraction V′ and ψ, respectively. The parameter V′ was utilized to explain the variation of the dynamic elastic modulus E′ at 1 % double strain amplitude (DSA) for all rubber compounds. The parameter ψ was used to explain the variation of E′ at 25% DSA and the factor σ in the calculation of I. The parameters V′ and ψ provide a model for the estimation of I from fundamental carbon-black morphological properties and surface energy.

A Quantitative Study of the Carbon Black Reinforcement System for Tire Tread Compounds

1979 ◽  
Vol 52 (4) ◽  
pp. 748-763 ◽  
Author(s):  
A. G. Veith ◽  
V. E. Chirico
Keyword(s):  
Wear Resistance ◽  
Carbon Black ◽  
Surface Area ◽  
High Performance ◽  
Materials Science ◽  
Normal Structure ◽  
Wear Testing ◽  
Reinforcement System ◽  
Wear Rates ◽  
Carbon Blacks

Abstract This comprehensive program clearly shows the influence of the four defined reinforcement system variables. The tread wear testing conducted over an extremely wide severity range illustrates how the influence of each variable or factor changes as the tire use of test severity is changed. The quantitative influence of the four variables is best illustrated by the index severity gradient, while the index range serves as a quick indicator. The influence of each factor of the reinforcement system increases as general test severity is increased. Carbon blacks with high structure and surface area are substantially superior to blacks with normal structure and surface area at the higher test severities. At the higher general severities, increased oil content produces higher wear rates. At any given severity level, the rate of wear passes through a minimum as carbon black level is increased. The carbon black content at this minimum wear rate shifts to higher values as general severity is raised. Test results at a series of specific cornering force levels (0.10–0.30 g range) indicate that the relative wear of typical tread compounds demonstrates crossovers of index values. Compounds that show superior wear resistance compared to a reference compound at high cornering severities often show inferior wear resistance at low cornering severities. Therefore, for maximum tread life or wear resistance, the reinforcement system with any tread rubber or rubber blend must be carefully adjusted to the anticipated level of tire use severity. The introduction of improved-technology carbon blacks with increased rubber-black interaction that is promoted by high DBP and EMA levels is a substantial advancement in rubber materials science and is most important for the production of high-performance long-treadlife tires.

Investigation of Abrasion of Nitrile Rubber

1984 ◽  
Vol 57 (4) ◽  
pp. 769-778 ◽  
Author(s):  
S. W. Zhang
Keyword(s):  
Steady State ◽  
Carbon Black ◽  
Crack Growth ◽  
Unsteady State ◽  
Small Particles ◽  
Physical Processes ◽  
Wear Rates ◽  
Rubber Compounds ◽  
Dominant Process ◽  
Particulate Wear

Abstract Abrasion of NBR appears as a dry (particulate) wear, similar to unfilled BR, NR, and SBR, and filled BR. The abraded surface seems textured on two scales: that of the ridges of the abrasion pattern and that of small particles of debris. The formation of macroridges on filled and unfilled NBR appears to involve two distinct ridges one formed after the other. First, fine and tightly spaced primary ridges, followed by rough and sparsely spaced secondary ridges. The abrasion pattern on unfilled NBR is relatively stable once steady state has been reached and the pattern has been fully developed. As for the filled NBR, both the scale and roughness of the secondary ridges are uneven, even if steady state has been reached completely. Wear rates of filled and unfilled NBR have been found to be proportional to an exponent n of the applied frictional work. The unsteady state rates of wear were also somewhat dependent on the number of revolutions of the test wheel. Both the proportionality coefficient k and exponent n are dependent upon the composition and also upon the wear state. The exponent n for unfilled NBR is greater than that for filled NBR, and for the unsteady state it is greater than that for steady state. Reversals in the relative rates of wear between filled and unfilled NBR are also observed at different severities of abrasion. This phenomenon perhaps reflects a competition between two different physical processes: crack growth and rupture of tongue tip. The dominant process may be crack growth at low severities of wear and rupture of the tongue tip at high severities of wear. Therefore, the fact that, at high severities, carbon black markedly reduces the rates of abrasion might be attributed to the tensile strength gain of rubber compounds due to reinforcement by carbon black.

A Low-Cost, Rapid Method for Determining Carbon Black Surface Area

1983 ◽  
Vol 56 (2) ◽  
pp. 440-449 ◽  
Author(s):  
Jerry B. Pausch ◽  
Caroline A. McKalen
Keyword(s):  
Carbon Black ◽  
Surface Area ◽  
Low Cost ◽  
Control Procedure ◽  
Simple Method ◽  
Surface Areas ◽  
Measuring Surface ◽  
Headspace Gas ◽  
Black Surface ◽  
Area Data

Abstract For practical use of this method as a quality control procedure for carbon black, a combination of 4 mm3 and 6 mm octane doses appears to be the best compromise for a sample size of 0.1 g. These conditions cover well, a surface area range of 10–140 m2/g and surface areas up to 180 m2/g can be estimated. Larger doses of octane will extend the linear range on the high side, but the slope of the calibration curve is reduced significantly. A smaller slope yields lower precision. The regular testing of standards appears necessary to achieve optimum accuracy of surface area. At the present time, the method is calibrated against nitrogen surface area data, so the advantage of octane more closely simulating the rubber molecule is lost. We need to obtain adsorption isotherms that are better defined throughout the linear adsorption coefficient range for a number of carbon blacks, and thus become self-calibrated against octane. A more versatile dosing technique is preferred to enable these experiments to be run. An alternate approach is to correlate the headspace results with data obtained by other techniques such as CTAB. The advantages of automated headspace gas chromatography for measuring surface area have been outlined before . It is a rapid and simple method, which also exhibits relatively low labor involvement. The number of samples capable of being analyzed per day is significantly higher than by any other technique.

Silica Properties/Rubber Performance Correlation. Carbon Black-Filled Rubber Compounds

1994 ◽  
Vol 67 (2) ◽  
pp. 217-236 ◽  
Author(s):  
Timothy A. Okel ◽  
Walter H. Waddell
Keyword(s):  
Carbon Black ◽  
Physical Properties ◽  
Surface Area ◽  
Performance Characteristics ◽  
Rubber Compound ◽  
The Road ◽  
Precipitated Silica ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
As Stress

Abstract The effectiveness of predicting rubber performance based on measured silica physical properties in silica- and carbon black-filled compounds is presented for three rubber formulations: an off-the-road tire tread, a wire coat stock and a V-belt. Correlation and regression analyses were performed using SAS software for sixteen physical properties of thirteen precipitated silicas, and sixteen rubber compound performance characteristics of the three compounds. Silica physical properties studied include various measurements of surface area and structure, particle size, pH and impurities. Rubber performance characteristics studied include cure properties and physical properties such as stress/strain, tear strength, cut growth resistance, abrasion resistance and heat build-up. The present study confirms that silica surface area is the single best predictor of the effect that varying silica physical properties have on the physical performance of cured, carbon black-filled rubber compounds containing precipitated silica. Silica structure, as measured by DBP absorption and nitrogen or mercury pore volume, is a secondary predictor of certain rubber physical properties. The confidence limits of the predictions is dependent upon the concentration of precipitated silica used in the carbon black-filled rubber compound.

Another Look at S-Type Carbon Blacks

1977 ◽  
Vol 50 (1) ◽  
pp. 211-216
Author(s):  
J. R. Haws ◽  
W. T. Cooper ◽  
E. F. Ross
Keyword(s):  
Carbon Black ◽  
Surface Area ◽  
Good Adhesion ◽  
Good Resistance ◽  
Carbon Blacks ◽  
Rubber Compounds ◽  
Curing Characteristics ◽  
Wide Range ◽  
Oxidized Carbon

Abstract Oxidized carbon blacks impart unique properties to rubber compounds. The most interesting aspects include modified curing characteristics, good resistance to tear, and the potential to promote good adhesion of rubber compounds to brass-plated metal. When these improvements are considered in conjunction with the wide range of surface area and structure available in carbon black, it is evident that oxidized furnace blacks provide combinations of properties not previously available.

Relationship between Molecular Structure and Mixing Mechanism

1987 ◽  
Vol 60 (1) ◽  
pp. 14-24 ◽  
Author(s):  
S. Shiga
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Carbon Black ◽  
Mixing Time ◽  
Molecular Size ◽  
Rubber Compounds ◽  
Bound Rubber ◽  
Strong Linear Correlation ◽  
Black Surface ◽  
The Relationship

Abstract The relationship between the molecular weight, the bound rubber, and the PI value was studied for EPR, of which the molecular structure was measured with GPC-LALLS. A strong linear correlation is found between the bound rubber and the PI value. The Meissner theorem, modified to express a severer dependence of the bound rubber on the molecular weight than the original theorem expects and the use of a molecular size instead of the molecular weight, can explain the relationship between the molecular weight and the bound rubber, accordingly the PI value. They indicate not only the dependence of mixing processability on polymer adsorption, but also strongly suggest the mechanism of carbon black dispersion that aggregates are scraped out from the surface of agglomerates as illustrated by the onion model. A pulsed NMR was used to measure the spin-spin relaxation time T2 of EPR in rubber compounds of different mixing time to study the rubber phase structure and its time change. It can be imagined from the T2-time curves that till tmin, polymer molecules are rapidly bound on the carbon black surface to become thick gradually, while adsorbed segments per a molecule increase with time. After tmin, gradual rearrangement of molecules on the surface and the biphasic structure of the bound rubber may proceed. The whole thickness of the bound rubber increases gradually even after tmin. The resistance against the dispersion of carbon black seems to be strengthened with mixing time.

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