Carbon Black Structure Effects in Synthetic Rubbers

1961 ◽  
Vol 34 (4) ◽  
pp. 1141-1161
Author(s):  
T. D. Bolt ◽  
E. M. Dannenberg ◽  
R. E. Dobbin ◽  
R. P. Rossman
Keyword(s):  
Carbon Black ◽  
Term Structure ◽  
Primary Structure ◽  
Mechanical Strain ◽  
Secondary Structures ◽  
Spherical Particles ◽  
Carbon Blacks ◽  
Carbon Particles ◽  
Particle Association ◽  
High Degree

Abstract Carbon blacks are composed of spherical particles which are to varying degrees arranged in chainlike structures. This type of particle association, which is readily seen in electron photomicrographs of most carbon blacks, can be termed “primary structure”. The use of the term “structure” to describe interparticle association must not be confused with the basic intraparticle structure of an atomic crystallographic nature. There is strong evidence that primary structure units, and possibly individual particles, can further associate or flocculate in fluid or elastomeric systems. This is a secondary type of structure formation which can be readily disrupted under the influence of mechanical strain. Some investigators have used the term “structure” to describe this strain-sensitive flocculation behavior. It is suggested here that carbon blacks possess both primary structure features and the ability to form secondary structures by flocculation in dispersed systems. The tendency to form secondary structures is probably greater with carbon blacks possessing a high degree of primary structure. Unless otherwise specified, the term “structure” in this paper will be used in the sense of primary structure. The structure of carbon blacks is thought to originate in the flame by the agglomeration of growing carbon nuclei and particles. The appearance of electron micrographs of carbon blacks lends some support to the assumption of simultaneous agglomeration and growth processes. Carbon blacks having a broad particle size distribution are characterized by carbon black chains, where each chain is composed of particles of the same size, rather than a randomized distribution of various sized carbon black particles. Thus, these chainlike structures must result from the continued growth of agglomerates formed from neighboring carbon particles at the same stage of their growth history. This process results in a chemical fusing of these particles as layers of new carbon are deposited on the surfaces of actively growing agglomerates.

A Carbon Black Structure-Concentration Equivalence Principle. Application to Stress-Strain Relationships of Filled Rubbers

1971 ◽  
Vol 44 (1) ◽  
pp. 199-213 ◽  
Author(s):  
Gerard Kraus
Keyword(s):  
Carbon Black ◽  
Primary Structure ◽  
Equivalence Principle ◽  
Chemical Activity ◽  
Cross Linking ◽  
Surface Chemical ◽  
Deformation Structure ◽  
Carbon Blacks ◽  
Filled Rubbers ◽  
Dependent Factor

Abstract It is shown that various modulus values of carbon black reinforced rubber are functions of the product of the actual black loading and a structure dependent factor. The structure factor appears to be a linear function of the so-called 24M4 value of the dibutylphthalate absorption and is independent of elongation, temperature, and degree of cross-linking over the ranges covered by the data reported. An interpretation of the results is offered based on the idea of polymer occluded in the interstices of primary structure aggregates and thereby shielded from deformation. Structure-concentration equivalence can only be demonstrated with carbon blacks differing in (primary) structure alone. Deviations are observed whenever the carbon blacks compared vary significantly in specific surface area and surface chemical activity.

Filler Aggregates and Their Effect on Reinforcement

1974 ◽  
Vol 47 (2) ◽  
pp. 411-433 ◽  
Author(s):  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Fine Particles ◽  
High Surface ◽  
High Surface Area ◽  
Experimental Studies ◽  
Spherical Particles ◽  
Rubber Compound ◽  
Carbon Blacks ◽  
Reinforcing Fillers ◽  
Aggregate Nature

Abstract The most highly reinforcing fillers, namely carbon blacks and silicas, consist of aggregates of quasi-spherical particles fused together. In the absence of direct experimental studies with single-particle carbon blacks or silicas of high surface area, we cannot be sure if aggregated structure is essential for good reinforcement, or whether aggregation and fusion just happen to accompany the formation of fine particles at practical concentrations. In any case, there is no doubt that the aggregate nature of the filler plays a major role in determining the properties of the rubber compound. Here I would like to review what we know about filler aggregates, especially of carbon black, and suggest some mechanisms for their effects on rubber; and also indicate where our knowledge seems inadequate at the present time.

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.

Effects of Processing Variables on the Mechanical Properties of Carbon Black Filled Rubber

1978 ◽  
Vol 51 (5) ◽  
pp. 1006-1022 ◽  
Author(s):  
B. Wijayarathna ◽  
W. V. Chang ◽  
R. Salovey
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Secondary Structure ◽  
Carbon Black ◽  
Term Structure ◽  
Primary Structure ◽  
Filler Particle ◽  
Structural Heterogeneity ◽  
Mixing Process ◽  
High Structure

Abstract Vulcanizate properties such as tensile strength, abrasion resistance, and tear resistance, are often enhanced by the introduction of structural heterogeneity. This is usually achieved by incorporating fillers into the polymer matrix. In addition to the type of filler and polymer used, mechanical properties depend on factors such as filler particle size, distribution, filler-polymer interaction, and network homogeneity. These factors are largely governed by the conditions of the mixing. The most widely used filler in rubber is carbon black. Carbon black, produced by the pyrolysis of hydrocarbons, is in the form of fused primary aggregates which flocculate to form large secondary aggregates held together by van der Waal forces. The term structure, as applied to carbon black, commonly refers to both primary and secondary aggregates and is designated as primary or secondary structure. The reinforcement of rubber by carbon black depends considerably on the particle size and structure of the black used. Voet and associates have shown evidence that the primary structure is not broken down by shearing action during mixing. However, Heckman and Medalia and Gessler claim that fracture of the primary structure could result from severe mechanical shear. The general consensus is that breakdown of the primary structure of carbon black is not extensive in the usual mixing process. Boonstra and Medalia, among others, reported that large agglomerates remaining after insufficient mixing have a deleterious effect on the rupture properties of vulcanizates. Hence, an optimal mixing process does not destroy secondary aggregates. The secondary structure plays an important role in the dispersion of carbon black during mixing as rubber is squeezed into both primary and secondary aggregates. Low structure blacks pack much more tightly than high structure ones and are more difficult to disperse.

The Effects of Heating and Cooling Rates on the Structure of Carbon Black Particles

1998 ◽  
Vol 71 (1) ◽  
pp. 26-37 ◽  
Author(s):  
T. W. Zerda ◽  
W. Xu ◽  
H. Yang ◽  
M. Gerspacher
Keyword(s):  
Surface Roughness ◽  
Carbon Black ◽  
Amorphous Carbon ◽  
Cooling Rates ◽  
Carbon Blacks ◽  
Carbon Particles ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Crystallite Sizes ◽  
Bet Technique

Abstract The effects of heating and cooling rates on the structure of N660 and N299 carbon black particles have been investigated using Raman spectroscopy, X-ray scattering, and the BET technique. Carbon blacks were kept at 2700 K for various lengths of time and next cooled down at different rates. The size of crystallites and the surface roughness of the particles have been determined for these different treatment schedules. The fractal dimension decreases from 2.2 for untreated samples to 2.0 for samples heat treated to 1300 K. Cooling rates do not affect the surface roughness. However, rapid cooling reduces crystallite sizes. We postulate that the surface of carbon particles is composed of crystallites and amorphous carbon. The amount of amorphous carbon depends on the thermal treatment. The role of amorphous carbon in determining reinforcing properties of carbon blacks in tires is discussed.

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.

scholarly journals THIXOTROPIC FLOCCULATION EFFECTS IN CARBON BLACK–REINFORCED RUBBER: KINETICS AND THERMAL ACTIVATION

2021 ◽  
Author(s):  
Lewis B. Tunnicliffe
Keyword(s):  
Carbon Black ◽  
Surface Area ◽  
Thermal Activation ◽  
Spherical Particles ◽  
Carbon Blacks ◽  
Creep Flow ◽  
Wide Range ◽  
Activation Data ◽  
Aggregate Morphology ◽  
Future Work

ABSTRACT A new rheological methodology is used to quantify the kinetics and thermal activation of thixotropic recovery (flocculation) of uncrosslinked carbon black–reinforced emulsion SBR following high shears and over a range of annealing temperatures. A wide range of carbon black types are examined to determine the influence of aggregate morphology and surface area on compound flocculation. Several kinetic parameters are correlated with the carbon black aggregate structure and surface area, the results of which imply a transition in mechanisms controlling modulus recovery between shorter and longer recovery time scales. Thermal activation of flocculation is found to scale to the surface area and to the mean aggregate diameter of the carbon blacks following power law relationships. The thermal activation data for a subset of compounds with different carbon blacks prepared at different loadings collapses onto a single master line by rescaling the data to a parameter that is proportional to the theoretical interparticle force calculated for the idealized situation of two spherical particles in proximity. Three different van der Waals force models are evaluated, and in each case, an effective superposition of the thermal activation data is achieved. This indicates that the attractive force between aggregates plays a key role in the flocculation of carbon black in rubber, and this force can be traced back to the aggregate and primary particle sizes, interaggregate distances, and effective volume fractions. The activation energy for the viscosity of the unfilled, uncrosslinked SBR is similar to analogous values calculated for the thermal activation of flocculation. This coupling of energetics may be the result of creep/flow of rubber out of gaps between aggregates resulting from interaggregate attractive forces and any potential diffusive motion of the aggregates. Bound rubber data appear to contain information relating to aggregate packing, which could be exploited in future work to further explore the mechanism of flocculation.

High Degree of Homology Between Primary Structure of Human Lysosomal Acid Phosphatase and Human Prostatic Acid Phosphatase

1989 ◽  
Vol 370 (1) ◽  
pp. 177-182 ◽  
Author(s):  
Christoph PETERS ◽  
Carola GEIER ◽  
Regina POHLMANN ◽  
Abdul WAHEED ◽  
Kurt VON FIGURA ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Primary Structure ◽  
Prostatic Acid Phosphatase ◽  
Lysosomal Acid ◽  
High Degree

PERMEABILITY STUDIES: III. SURFACE AREA MEASUREMENTS OF CARBON BLACKS

1948 ◽  
Vol 26a (2) ◽  
pp. 29-38 ◽  
Author(s):  
J. C. Arnell ◽  
G. O. Henneberry
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Carbon Black ◽  
Surface Area ◽  
Satisfactory Agreement ◽  
Nitrogen Adsorption ◽  
Average Particle ◽  
Carbon Blacks ◽  
Permeability Studies ◽  
Nitrogen Adsorption Isotherms

The modified Kozeny equation has been found to be satisfactory for the measurement of the specific surfaces of carbon blacks having average particle diameters ranging from 0.01 to 0.1 μ to within ±10%. Comparative data were obtained from electron microscope counting and from low temperature nitrogen adsorption isotherms. The three methods examined gave results that were in satisfactory agreement, except when the carbon black was porous, and then the adsorption value was extremely large.

scholarly journals Use of Electrosprayed Agave Fructans as Nanoencapsulating Hydrocolloids for Bioactives

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Jorge Ramos-Hernández ◽  
Juan Ragazzo-Sánchez ◽  
Montserrat Calderón-Santoyo ◽  
Rosa Ortiz-Basurto ◽  
Cristina Prieto ◽  
...  
Keyword(s):  
Uv Light ◽  
Particle Morphology ◽  
Bioactive Compound ◽  
Processing Parameters ◽  
Degree Of Polymerization ◽  
Spherical Particles ◽  
Sem Images ◽  
High Degree ◽  
Thermal Stability Of ◽  
Β Carotene

High degree of polymerization Agave fructans (HDPAF) are presented as a novel encapsulating material. Electrospraying coating (EC) was selected as the encapsulation technique and β-carotene as the model bioactive compound. For direct electrospraying, two encapsulation methodologies (solution and emulsion) were proposed to find the formulation which provided a suitable particle morphology and an adequate concentration of β-carotene encapsulated in the particles to provide a protective effect of β-carotene by the nanocapsules. Scanning electron microscopy (SEM) images showed spherical particles with sizes ranging from 440 nm to 880 nm depending on the concentration of HDPAF and processing parameters. FTIR analysis confirmed the interaction and encapsulation of β-carotene with HDPAF. The thermal stability of β-carotene encapsulated in HDPAF was evidenced by thermogravimetric analysis (TGA). The study showed that β-carotene encapsulated in HDPAF by the EC method remained stable for up to 50 h of exposure to ultraviolet (UV) light. Therefore, HDPAF is a viable option to formulate nanocapsules as a new encapsulating material. In addition, EC allowed for increases in the ratio of β-carotene:polymer, as well as its photostability.

Sign in / Sign up

Export Citation Format

Share Document