Applications of carbon black

Electrical properties such as volume resistivity and surface resistivity of blend samples are furnished. Blend with 30 phr carbon black was found to be overloaded in terms of both volume resistivity and surface resistivity. That is, the resistivity of these formulations was lower than the limit of the testing equipment. This is an effect of the quasigraphitic microstmcture of the carbon black this makes the blend more electrically conductive. The higher the surface/volume resistivity, the lower the leakage current and the less conductive the material is. The major application of carbon black... 

Other applications of carbon-black-filled polymers do not require as low a level of conductivity. The purpose is the dissipation of static electricity. These types of compoimds are used in carrying containers for microelectronic components and in containers and pipes for combustible liquids such as gasoline. The newest application is adding enough conductivity to automobile panels to enable coatings of electrostatically charged paint particles. 

Carbon Fillers. The application of carbon black (qv) in rubber compounds is over a hundred years old. Unlike the well-known crystalline forms of carhon, such as diamond and graphite, carbon black is amorphous and is a manufactured product (79,80). Carbon blacks are prepared by incomplete combustion of hydrocarbons or by thermal cracking. Presently, almost all rubber-reinforcing blacks are manufactured by the oil furnace process. A fuel is burned in an excess of air to produce finely divided carbon. Furnace blacks have low oxygen contents with neutral or alkaline surfaces. In the thermal process, oil or natural gas is cracked in an absence of oxygen to produce unoxidized blacks of small surface areas, or thermal blacks. 

The major application of carbon-black-reinforced elastomers is in the manufacture of automotive tires. Table 9.5 illustrates an automotive tire recipe involving synthetic rubber. The synthetic-rubber recipes usually contain two or more elastomers that are blended together with the other ingredients and then covulcanized. 

The main applications of carbon black are for ultra-violet light and thermal protection as well as the control of electrical conductivity. It... 

Table 11. Types and Applications of Special Pigment Grades of Carbon Blacks...

At the other extreme, in the formation of composite materials, especially filled polymers, fine particles must be dispersed into a highly viscous Newtonian or non-Newtonian liquid. The incorporation of carbon black powder into rubber is one such operation. Because of the large surface areas involved, surface phenomena play an important role in such applications. 

Carbon black may serve as a low-cost additive for controlling the gas migration in cement slurries [303]. It is intended as a suitable substitute for polymer latex and silica fume and has been tested in field applications [304,1256]. The concentration of carbon black varies from 2 to 20 parts, based on the weight of the dry cement [1220]. The particle size varies from 10 to 200 nm. A surfactant is necessary for dispersion, for example, formaldehyde-condensed naphthalene sulfonate or sulfonated cumarone or indene resins. 

The styrenic thermoplastic elastomers are the only type which are fully compounded in the manner of conventional elastomers. In this case, however, the addition of carbon black, or other fillers, does not give reinforcement. Additions of polystyrene, or high impact polystyrene, and oil are used to vary hardness and tear strength, and fillers can be used to cheapen the material. Other added polymers, e g., EVA, can be used to increase ozone resistance. These materials also require antioxidants for protection during processing and service life, and the poor UV stability restricts their use in outdoor applications. 

Carbon black (soot). It is obtained by the incomplete combustion of natural gas or liquid hydrocarbons. The particle size of carbon black is very small its applications are mainly in rubber industry (to strengthen and reinforce rubber) and also as a pigment in the preparation of inks, etc. 

Of the 10% of carbon black used for nonrubber applications, about 35% is used for plastics, 30% for printing inks, 10% coating, and 5% for paper. In plastics, carbon black... 

Schmid et al. used the same principle to develop sensors to be incorporated into FI systems for the determination of ascorbic acid in fruit juices [38] and that of lactic acid in dairy products [39]. The membrane used in both applications consisted of decacyclene dissolved in silicone rubber that was treated similarly as the membrane in glucose sensors (Fig. 3.4.B). The oxygen optrode was coated with a sheet of carbon black as optical insulation in order to protect it from ambient light or intrinsic sample fluorescence. Ascorbic acid oxidase or lactic acid oxidase was immobilized by adsorbing it onto carbon black and cross-linking it with glutaraldehyde. The FI system automatically buffered and diluted the food samples, thereby protecting the biosensor from a low pH and interferents. 

The furnace process involves injecting low end fraction of cmde oil, eg, Bunker Fuel C, into a heated chamber. The temperature, shape of the injectors of the oil, rate of injection, and other factors are controlled to produce black fillers of different particle size and structure. The particle size and structure control the reinforcing character of the carbon black. There are 30 common grades of carbon black used in the mbber industry. There are numerous specialty grades produced, and several hundred are used in plastic, conductive applications, and other uses. 

A number of processes have been used to produce carbon black including the oil-furnace, impingement (channel), lampblack, and the thermal decomposition of natural gas and acetylene (3). These processes produce different grades of carbon and are referred to by the process by which they are made, eg, oil-furnace black, lampblack, thermal black, acetylene black, and channel-type impingement black. A small amount of by-product carbon from the manufacture of synthesis gas from liquid hydrocarbons has found applications in electrically conductive compositions. The different grades from the various processes have certain unique characteristics, but it is now possible to produce reasonable approximations of most of these grades by the oil-furnace process. Since over 95% of the total output of carbon black is produced by the oil-furnace process, this article emphasizes this process. 

U.S. consumption of carbon black in 1988 by various market sectors is shown in Table 6. About 90% of total consumption is in the mbber industry and 69% for tires. About 10% is consumed for other automotive products and 11% for rubber products unrelated to the automotive industry. The automotive industry accounts for 79% of consumption. Pigment applications account for about 10% of consumption, most of this for plastics and printing inks. Western Europe consumes 74% in tires and other automotive products and almost 20% in other industrial mbber products. Pigment applications in Western Europe and Japan are 5—6% of consumption. 

Today at least 35 different types of carbon black are used as fillers in rubber, and about 80 types of carbon black are used in pigments or special applications. The total world production in 1994 was 6 x 1061. More than 90% of the carbon black was produced for the use in the rubber industry. 

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