Filler carbon black

Shock isolation is also possible usiag the dampiag characteristics of FZ elastomer. Dynamic mechanical analysis iadicates multiple transitions and a broad dampiag peak. This dampiag can be enhanced usiag formulatioas containing both siUca and carbon black fillers. 

Colour. The colour of resins ranges from water-white to dark brown. Colour may be an important factor in resin choice depending on end use. Pale colours are necessary in some types of adhesives, whereas darker colours may be tolerated in rubber formulations, especially where carbon black filler is incorporated. Medium-coloured resins can be used in most adhesive formulations. 

The underlying nonlinearity function m (A). which is independent of the type of deformation, is very similar for different amorphous rubbers. For SBR, it is independent of the cross-link" density over moderate changes in cross-link density (62) and independent of the temperature down to —40°C, a temperature where the modulus has increased by a factor of 2 to 3 over the room-temperature value (61). The function A) is insensitive to the presence of moderate amounts of carbon black filler for strains up to about 100% (63). 

Properties of peroxide cross-linked polyethylene foams manufactured by a nitrogen solution process, were examined for thermal conductivity, cellular structure and matrix polymer morphology. Theoretical models were used to determine the relative contributions of each heat transfer mechanism to the total thermal conductivity. Thermal radiation was found to contribute some 22-34% of the total and this was related to the foam s mean cell structure and the presence of any carbon black filler. There was no clear trend of thermal conductivity with density, but mainly by cell size. 27 refs. 

Some polymeric objects, such as rubber tires, are black because of the presence of high proportions of carbon black filler. Many other products, including some paints, are white because of the presence of titanium dioxide (titanium (IV) oxide), the most widely used inorganic pigment. Over 50,000 t of colorants are used annually by the polymer industry. 

Light. Ultraviolet (uv) light promotes free-radical oxidation at the mbber surface which produces discoloration and a brittle film of oxidized mbber (35). This skin cracks in random directions to form a pattern called crazing, which can be prevented by the addition of carbon black fillers or uv stabilizers. Black stocks are more resistant to uv light than are gum or light-colored stocks. Nonblack compounds require larger quantities of nonstaining antioxidants which should bloom to the surface as the surface uv stabilizers deplete. 

Fig. 13. Viscosity/shear stress relationship for EPDM compounds at 100 °C at various carbon black filler levels [50]...

The original coupling agents, which were called promotors, were used to ensure a good bond between rubber and the carbon black filler. These promotors increase the tensile strength, modulus, and the bound rubber (the insoluble mixture of filler and rubber) content of rubber. Although natural rubber is soluble in benzene, it becomes less soluble when carbon black or amorphous silica is added. 

Like ldpe, polybutadienes are resistant to most nonoxidizing acids, alkalis, and salts. However, because they are unsaturated, the polyalkadienes are attacked by hydrochloric, hydrobromic, and hydrofluoric acids, as well as by hydrogen and chlorine. The reaction products, which are thermoplastic, have been used as commercial nonelastomcric plastics. NR and other diene elastomers are also attacked by peroxides and ozone. In the absence of an tioxidants and carbon black filler, these unsaturated elastomers are degraded in the sunlight. 

Plasma Polymerization onto Silica and Carbon Black Fillers, and onto Sulfur Vulcanization Agent... 

EJ (Propellants). American sol vent-extruded propellants developed during WWII at the Allegheny Ballistics Laboratory and at the Radford Development Department of the Hercules Powder Co. They oontd K oer-chlorate-carbon black filler in a double-base propint matrix... 

From a fit of Equation (10) to spatially resolved relaxation curves, images of the parameters A, B, T2, q M2 have been obtained [3- - 32]. Here A/(A + B) can be interpreted as the concentration of cross-links and B/(A + B) as the concentration of dangling chains. In addition to A/(A + B) also q M2 is related to the cross-link density in this model. In practice also T2 has been found to depend on cross-link density and subsequently strain, an effect which has been exploited in calibration of the image in Figure 7.6. Interestingly, carbon-black as an active filler has little effect on the relaxation times, but silicate filler has. Consequently the chemical cross-link density of carbon-black filled elastomers can be determined by NMR. The apparent insensitivity of NMR to the interaction of the network chains with carbon black filler particles is explained with paramagnetic impurities of carbon black, which lead to rapid relaxation of the NMR signal in the vicinity of the filler particles. 

Mixing process Technical rubbers are blends of up to about 30 different compounds like natural rubber, styrene-butadiene rubber, silicate and carbon-black fillers, and mobile components like oils and waxes. These components show a large variety of physical, chemical, and NMR properties. Improper mixing leads to inhomogeneties in the final product with corresponding variations in mechanical and thermal properties (cf. Figure 7.4). 

Figure 7.21 Temperature profiles from T2 parameter images of SBR cylinders with different carbon-black filler contents undergoing oscillatory shear deformation (a) Temperature calibration curves, (b) Temperature profiles across the cylinders...

The presence of carbon black filler increases the linewidths in the spectra from both phases of a blend, and as a result comparison could only be made of the relative crosslink density [102]. Later the authors showed that H% in the presence of filler in blends of NR and EPDM was linearly related to H% in the unfilled blend [103]. In blends of NR and BR a small excess of the sulfur reacted in the NR phase compared with the BR. Measurement in unfilled blends allowed crosslink densities to be determined, and confirmed the greater yield of crosslinking in the NR, is shown in a plot of H% against crosslink density [104]. 

H and 2H NMR have been used in styrene-butadiene rubber (SBR) with and without carbon-black fillers to estimate the values of some network parameters, namely the average network chain length N. The values obtained from both approaches were checked to make sure that they were consistent with each other and with the results of other methods [71, 72, 73]. To this purpose, a series of samples with various filler contents and/or crosslink densities were swollen with deuterated benzene. The slopes P=A/ X2-X 1) obtained on deuterated benzene in uniaxially stretched samples were measured. The slopes increase significantly with the filler content, which suggests that filler particles act as effective junction points [72, 73]. 

Deuterated PB networks filled with carbon black have been investigated recently [74]. The 2H NMR lineshape is different from that in unfilled elastomers an asymmetric doublet is observed as the sample is uniaxially stretched (A,=1.8)). This asymmetry is related to the presence of carbon black fillers, which induce magnetic inhomogeneities. 

When a sinusoidal strain is imposed on a linear viscoelastic material, e.g., unfilled rubbers, a sinusoidal stress response will result and the dynamic mechanical properties depend only upon temperature and frequency, independent of the type of deformation (constant strain, constant stress, or constant energy). However, the situation changes in the case of filled rubbers. In the following, we mainly discuss carbon black filled rubbers because carbon black is the most widespread filler in rubber products, as for example, automotive tires and vibration mounts. The presence of carbon black filler introduces, in addition, a dependence of the dynamic mechanical properties upon dynamic strain amplitude. This is the reason why carbon black filled rubbers are considered as nonlinear viscoelastic materials. The term non-linear viscoelasticity will be discussed later in more detail. 

A generalized kinetic model of cure is developed from the aspect of relaxation phenomena. The model not only can predict modulus and viscosity during the cure cycle under isothermal and non-isothermal cure conditions, but also takes into account filler effects on cure behavior. The increase of carbon black filler loading tends to accelerate the cure reaction and also broadens the relaxation spectrum. The presence of filler reduces the activation energy of viscous flow, but has little effect on the activation energy of the cure reaction. 

Carbon black filler in natural rubber not only serves to increase the modulus of the elastomer, but also tends to accelerate the cure reaction. 

Substitution of carbon black filler (or a significant part of it) with white reinforcing fillers (e.g. silica), as carbon black has also been found to act as a nitrosating agent. 

The use of carbon black fillers in mbbers is commonplace, but they can contain low molecular weight organic compounds (e.g. aromatics) due to their method of production (burning of oil). Carbon blacks have an important influence on both the physical (e.g. tensile strength and processing viscosity)... 

It can be seen that under these conditions high amounts of aromatics are produced. The benzene content is 12.2 wt% at a pyrolysis temperature of 740°C and 24.75 at 780°C. Other main components of the PE pyrolysis (780°C) are methane, ethylene, and propene as gas and toluene, naphthalene as aromatics. The amount of carbon soot is low. Tire pyrolysis produces mainly carbon black (filler), gas, and aromatics. Steel cord is one of the other main products if whole tires are fed. 

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