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.

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.

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.

Filler-Elastomer Interactions. Part XI. Investigation of the Carbon-Black Surface by Scanning Tunneling Microscopy

1994 ◽  
Vol 67 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Meng-Jiao Wang ◽  
Siegfried Wolff ◽  
Burkhard Freund
Keyword(s):  
Carbon Black ◽  
Scanning Tunneling Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Energy Distributions ◽  
Carbon Blacks ◽  
Carbon Black Surface ◽  
Versatile Tool ◽  
Black Surface ◽  
Stm Images

Abstract Scanning tunneling microscopy (STM) has recently been demonstrated to be a powerful and versatile tool to image the microstructure of the surface of carbonaceous materials. In this study, the surfaces of carbon blacks, both graphitized and nongraphitized, were investigated with this technique. The STM images show that the carbon-black surface can be classified into two domains, an organized and an unorganized one. The degree of carbon atom organization varies with the carbon-black grade and increases drastically upon graphitization. The surface energies and energy distributions of graphitized and nongraphitized carbon blacks, measured by inverse gas chromatography, correlate well with their surface microstructure. Mapping of the carbon-black topography showed that although the surface is not smooth, there is no significant porosity either.

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.

Radiotracer Studies of Carbon Black Surface Interactions with Organic Systems. I. Experimental Approach and Initial Results from Chemisorption and Vinyl Polymerization Studies

1968 ◽  
Vol 41 (2) ◽  
pp. 382-399 ◽  
Author(s):  
Marvin L. Deviney ◽  
Lawrence E. Whittington
Keyword(s):  
Carbon Black ◽  
Functional Groups ◽  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Surface Interactions ◽  
Carbon Surface ◽  
Organic Systems ◽  
Carbon Black Surface ◽  
Basic Reaction ◽  
Black Surface

Abstract Radiotracer techniques have been applied to the study of interactions of carbon black surface functional groups with two chosen organic systems. The basic reaction mechanisms demonstrated in this study may have implications in elastomer reinforcement. Direct radiochemical evidence supports the conclusions of Hallum and Drushel (based on less direct polarographic data) that surface quinonic groups exhibit hydrogen abstraction activity toward tertiary hydrogens in paraffinic hydrocarbons. Studies on the system carbon black and styrene using tritium radiotracer have provided direct evidence that phenolic hydrogens participate in the polymerization acceleration and graft polymer formation reaction and are transferred to the growing polystyrene chains as postulated by Donnet. Several methods have been developed for specifically labelling certain oxygenated functional groups on the carbon surface with tritium and for tritium labelling carbon black in aromatic hydrogen positions. The techniques developed in this work and the basic reaction mechanisms derived will permit this investigation to be extended into a radiochemical study of carbon black surface interactions with elastomer related systems of interest to the rubber industry.

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