Carbon-Black-Elastomer Interaction

1991 ◽  
Vol 64 (1) ◽  
pp. 19-39 ◽  
Author(s):  
J. A. Ayala ◽  
W. M. Hess ◽  
F. D. Kistler ◽  
G. A. Joyce
Keyword(s):  
Carbon Black ◽  
Surface Activity ◽  
Chemical Reactivity ◽  
Surface Reactivity ◽  
Moisture Adsorption ◽  
Carbon Blacks ◽  
Bound Rubber ◽  
Carbon Black Surface ◽  
Black Surface ◽  
Polymer Interaction

Abstract A number of different techniques were applied to measure carbon-black-surface reactivity and the level of black-polymer interaction in four different elastomer systems (SBR, IIR, NR, and NBR) representing differences in unsaturation, crystallinity and polarity. Known within-grade surface activity variations were based on partial graphitization of an N121-type carbon black. The surface activity of different black grades was studied as a function of variations in both surface area and DBPA. Direct measurements of carbon-black-surface reactivity were based on hydrogen analysis, SIMS, IGC, and moisture adsorption. In-rubber measurements included bound rubber, SIMS of cut surfaces, and an interaction parameter, σ/η, which is derived from the slope (σ) of the stress-strain curve at low elongations, and (η), the ratio of dynamic modulus (E′) at 1% and 25% DSA. The following trends were observed: 1. The σ/η values provided a good measure of black-polymer interaction in all four polymer systems for either the within-grade or across-grade comparisons. 2. Higher σ/η values were indicated for SBR and NBR, followed by NR and IIR in that order. 3. SBR indicated the greatest sensitivity for bound-rubber measurements in terms of distinguishing within-grade variations in black-polymer interaction, followed by IIR, NR, and NBR in that order. 4. Positive SIMS on dry carbon black indicates the presence of complex hydrocarbon structures suitable for chemical reactivity at the carbon-black surface. 5. SIMS analyses on the dry carbon blacks exhibited intensity variations in the negative hydrocarbon fragments which were in line with the within-grade variations in hydrogen content. 6. SIMS analyses on the cut-rubber compound surfaces showed overall variations in intensity which were proportional to the range and level of the bound-rubber measurements. The most meaningful variations were recorded for SBR and IIR. 7. Heats of adsorption derived from IGC measurements with different adsorbates showed an excellent correlation with black-polymer interaction for the within-grade studies. Measurements across grades did not correlate as well with the in-rubber measurements, but the best results were obtained using styrene as the adsorbate. 8. The within-grade moisture adsorption measurements showed excellent agreement with IGC and the other techniques for the N121 series of heat-treated carbon blacks.

New Studies on the Surface Properties of Carbon Blacks

1990 ◽  
Vol 63 (5) ◽  
pp. 747-778 ◽  
Author(s):  
J. A. Ayala ◽  
W. M. Hess ◽  
A. O. Dotson ◽  
G. A. Joyce
Keyword(s):  
Carbon Black ◽  
Hydrogen Content ◽  
Surface Reactivity ◽  
Moisture Adsorption ◽  
Carbon Blacks ◽  
Surface Sites ◽  
Bound Rubber ◽  
Carbon Black Surface ◽  
Black Surface ◽  
Polymer Interaction

Abstract A series of carbon blacks of widely varying morphology and microstructure were analyzed for surface compositional properties employing SIMS, XPS/ESCA, and GC-MS. These studies were supported by bulk analyses for hydrogen and oxygen content. Surface reactivity was assessed by means of inverse gas chromatography, moisture adsorption, and oxidation in an oxygen plasma. To directly assess carbon-black-polymer interaction, the carbon blacks were evaluated in SBR and IIR compounds for stress-strain and dynamic properties as well as bound rubber. The major findings of these studies are: 1. The combined results of hydrogen content, SIMS, and pyrolysis-GC-MS suggest a complex hydrogen functionality at the carbon-black surface, which governs the level of interaction with elastomers. 2. SIMS analyses have shown that the hydrogen functionality at the carbon-black surface is preserved after an 1173 K heat treatment in an inert atmosphere. 3. Gas-solid chromatography results indicate that this technique may be very useful to determine the degree of heterogeneity of a carbon-black surface. It also provides a tool to characterize the nature of the surface sites which are responsible for such a heterogeneity. 4. Moisture-adsorption rates provides a means to explore the reactivity of carbon-black-surface sites. Initial rates of adsorption can be well explained by a second-order-rate mechanism. 5. Bound-rubber development (SBR) and oxygen content per square meter of carbon-black-surface area were directly proportional to the hydrogen content of the black. The hydrogen content is considered to be the primary compositional factor relating to carbon-black-surface activity, while bound rubber and oxygen levels are specific measures of surface reactivity. 6. The slope of the stress-strain curves (or the modulus value) in the λ=1 to 3 region divided by the black networking factor, η (E′ at 2% ptp ÷ at 25% ptp), is sensitive to changes in black-polymer interaction. This ratio (σ/η or M/η) shows an excellent correlation with black hydrogen content and bound rubber (SBR). 7. The σ/η values for SBR and IIR are highly correlated, although the values for SBR are two to three times higher, and there was no measurable bound rubber for any of the IIR compounds. 8. The σ/η values for IIR (λ=2−3) and the oxygen/m2 values were found to be the best discriminators for black-polymer interaction in explaining within-grade treadwear variations in SBR/BR multisection radial-passenger treads.

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.

Surface Activity and Chemistry of Thermal Carbon Blacks

2000 ◽  
Vol 73 (2) ◽  
pp. 293-309 ◽  
Author(s):  
H. Darmstadt ◽  
N-Z. Cao ◽  
D. M. Pantea ◽  
C. Roy ◽  
L. Sümmchen ◽  
...  
Keyword(s):  
Natural Gas ◽  
Surface Energy ◽  
Carbon Black ◽  
Surface Morphology ◽  
Specific Surface ◽  
High Purity ◽  
Carbon Blacks ◽  
Carbon Black Surface ◽  
Black Surface ◽  
Concentration Of Impurities

Abstract The surface energy of thermal and furnace carbon blacks was determined by inverse gas chromatography (IGC) at infinite dilution. In general, the specific surface energy decreases with decreasing carbon black specific surface area. However, there is also an influence of the concentration of impurities during the carbon black production. The surface energy decreases with decreasing concentration of impurities. The carbon black surface and bulk chemistry was studied by electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectroscopy (SIMS) and Raman spectroscopy. Scanning tunnelling microscopy (STM) was used for characterization of the surface morphology. Thermal grades of carbon black produced from high purity natural gas feedstock do not contain fewer surface functional groups than the other grades. No correlation between the concentration and nature of the oxygen and sulphur surface groups and the carbon black surface energy was found. Instead, a correlation between the surface energy and the polyaromatic character of the carbon black surface exists. Both increased in the order: thermal blacks from high purity natural gas feedstock < thermal black from oil feedstock < furnace blacks. The increase of the surface energy might be related to the formation of active sites which are formed upon removal of non-carbon elements during the carbon black formation. There was no principal difference in the surface morphology of thermal blacks from high purity gas feedstock and other blacks.

Effect of Heat Treatment on Reinforcing Properties of Carbon Black

1956 ◽  
Vol 29 (1) ◽  
pp. 286-295
Author(s):  
W. D. Schaeffer ◽  
W. R. Smith
Keyword(s):  
Carbon Black ◽  
Volatile Matter ◽  
Graphitized Carbon Black ◽  
Carbon Surface ◽  
Minor Effect ◽  
Carbon Blacks ◽  
Carbon Black Surface ◽  
Black Surface ◽  
High Degree ◽  
Degree Of Graphitization

Abstract The high degree of stiffness or modulus which reinforcing carbon blacks impart to rubber has often been associated with reinforcement. Modulus appears to be associated with the chemical nature of the carbon black surface ; when the carbon black surface is cleaned of combined oxygen and hydrogen, a drastic drop in modulus occurs, and this is not accompanied by an equally drastic decrease in tire road wear. Reinforcing and semireinforcing carbon blacks have been heat-treated at successive increments through a temperature range of 1000° to 2700° C. Treatment up to 1500° results in removal of all combined oxygen and hydrogen, followed by an increasing degree of graphitization at higher temperatures. These carbon blacks have been compounded in a standard natural-rubber compound and properties evaluated. Modulus is profoundly altered by the chemistry of the carbon surface. Electrical resistivity passes through a minimum at 1500° C. Scorchiness or premature vulcanization improves with removal of volatile matter. The degree of graphitization of the carbon has only a minor effect on rubber properties. A highly graphitized carbon black still imparts a high degree of resistance to abrasive wear to tire treads.

Surface Morphology of Thermal, Furnace and Pyrolytic Carbon Blacks by Nitrogen Adsorption - Relation to the Electrical Conductivity

2002 ◽  
Vol 75 (4) ◽  
pp. 691-700 ◽  
Author(s):  
Dana Pantea ◽  
Hans Darmstadt ◽  
Serge Kaliaguine ◽  
Silvia Blacher ◽  
Christian Roy
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Surface Morphology ◽  
Nitrogen Adsorption ◽  
Pyrolytic Carbon ◽  
Defect Concentration ◽  
Carbon Blacks ◽  
Carbon Black Surface ◽  
Black Surface ◽  
Surface Morphologies

Abstract The surface morphology of various carbon blacks was studied by low-pressure nitrogen adsorption. The shape of their low-pressure nitrogen isotherm depends on the concentration of surface defects. This defect concentration on the surface is different for thermal blacks, even for those of the same grade. Different surface morphologies were also observed for carbon blacks obtained by pyrolysis of truck tires. The concentration of defects increased with pyrolysis pressure. For the various furnace blacks, however, similar surface morphologies were observed. The electrical conductivity of thermal and pyrolytic carbon blacks decreases with increasing defect concentration. However, in spite of a similar surface morphology, different conductivities were observed for furnace blacks. The carbon black surface morphology is therefore not a determining factor for the electrical conductivity. Furthermore, the graphitic character of the carbon black surface was studied by secondary ion mass spectroscopy (SIMS). For thermal, furnace and pyrolytic carbon blacks, the conductivity increased with increasing graphitic character of the carbon black surface, thus underlining the importance of this parameter.

Radiotracer Studies of Carbon Black Surface Interactions with Organic Systems. II. Use of Sulfur-35 in Initial Studies on the Reactivity of “Bound” Surface Sulfur

1970 ◽  
Vol 43 (2) ◽  
pp. 449-463 ◽  
Author(s):  
J. E. Lewis ◽  
M. L. Deviney ◽  
C. F. McNabb
Keyword(s):  
Carbon Black ◽  
Pilot Plant ◽  
Elemental Sulfur ◽  
Chemical Reactivity ◽  
Phosphorus Compounds ◽  
Tetramethylthiuram Disulfide ◽  
Organic Systems ◽  
Physical Testing ◽  
Carbon Black Surface ◽  
Black Surface

Abstract A broad investigation has been undertaken, using primarily radiochemical techniques, of the reactivity of the insoluble or “bound” sulfur on the surface of carbon blacks. The carbon black samples used in this study were prepared in small pilot plant reactors from sulfur-free commercial feedstocks to which had been added, in separate experiments, sulfur-35 tagged elemental sulfur, dibenzothiophene-S-35 and dibenzyl disulfide-S-35. After careful extraction-purification of the blacks, “chemical probe” studies were undertaken to gain knowledge of the nature of the surface sulfur complexes or functional groups, using reagents such as LiAlH4, trivalent phosphorus compounds, tetramethylthiuram disulfide, and hydrogen. These experiments demonstrated that bound surface sulfur possesses a considerable amount of chemical reactivity. Experiments were next designed to determine whether or not bound surface sulfur becomes involved in vulcanization reactions by, for example, exchange with added curing sulfur or accelerator. In radiotracer studies with SBR, natural rubber, and cis-polybutadiene vulcanizates, the results demonstrated that bound surface sulfur enters into the rubber phase during vulcanization. Finally, results from preliminary rubber physical testing and practical vulcanization studies involving pilot plant blacks (2% wt. sulfur) indicate that surface sulfur has little effect upon the vulcanization or final physical properties of SBR and NR.

Characterization of Polymer Adsorption on Disordered Filler Surfaces by Transversal 1H NMR Relaxation

1997 ◽  
Vol 70 (5) ◽  
pp. 747-758 ◽  
Author(s):  
H. Lüchow ◽  
E. Breier ◽  
W. Gronski
Keyword(s):  
Surface Roughness ◽  
Carbon Black ◽  
1H Nmr ◽  
Nmr Relaxation ◽  
Rubber Matrix ◽  
Adsorption Sites ◽  
Bound Rubber ◽  
Carbon Black Surface ◽  
Black Surface ◽  
Tan Δ

Abstract The transversal 1H NMR relaxation of the bound rubber shell of carbon black loaded elastomers can be decomposed into three relaxation regimes corresponding to the loosely bound rubber, the rubber that is immobilized on the carbon black surface and a third component of intermediate mobility. The relaxation time T2 of the intermediate component is related to the end-to-end distance of polymer segments between adsorption sites on the carbon black surface, by converting the relaxation times to length scales on the basis of recent work on NMR relaxation of elastomeric networks. From measurements on SBR loaded with carbon black N 220, a distance of 2.3 nm was obtained in agreement with characteristic dimensions of crystallite sizes and surface roughness as determined by atomic force and scanning tunneling microscopy. The analysis was applied to novel inversion blacks which give lower tan δ/60°C, and rolling resistance without affecting tan δ/0°C and wet skid behavior. These blacks were found to possess a higher density of adsorption sites and a greater surface roughness as compared to standard carbon blacks. In addition to the surface characterization, the analysis of the mobile component of the compound allowed the estimation of the density of entanglement couplings between the rubber matrix and the bound rubber shell.

Transfer of Labeled Hydrogen between Elastomers and Carbon Black

1969 ◽  
Vol 42 (4) ◽  
pp. 1200-1208 ◽  
Author(s):  
E. Papireb ◽  
A. Voet ◽  
P. H. Given
Keyword(s):  
Carbon Black ◽  
Active Sites ◽  
Hydrogen Exchange ◽  
Surface Oxide ◽  
Radical Chain ◽  
Carbon Blacks ◽  
Reactive Carbon ◽  
Determining Factors ◽  
Carbon Black Surface ◽  
Black Surface

Abstract Radioactive hydrogen exchange was studied between tritium labeled carbon blacks and elastomers as well as between tritium labeled elastomers and carbon blacks, after solvent mixing and after milling. A substantial exchange was observed upon solvent mixing of an unsaturated elastomer (SBR) and a reinforcing black (HAF), with commercial blacks as well as in carbon black samples from which surface oxide groups were removed by calcination. Milling did not significantly increase the hydrogen exchange. Nonreinforcing blacks did not show any exchange. Saturated elastomers, such as butyl rubber, which bond predominantly to the carbon black particles by means of surface oxide complexes, did not show any significant hydrogen exchange, not even with channel blacks. The phenomena could be adequately explained by assuming as the material basis of reinforcement of unsaturated elastomers a process of chemisorption through abstraction of reactive hydrogen from the elastomer to a reactive site on the carbon black surface, followed by a chemical reaction of the resulting elastomer free radical chain with another reactive carbon black site. Thus, active sites on the carbon black surface and reacting hydrogen in the unsaturated elastomer are the determining factors in reinforcement.

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