Electrical resistivity, carbon black pigments

Vulcani2ed mbber is an insulator (volume resistivity is 10 Q-cm), and the static generated by mbber tires created serious problems in vehicles until the introduction of electrically conductive carbon black as a reinforcing pigment. An excellent correlation was found between the potential generated and the resistivity of the tires (127,128) (see Rubber natural). 

The physical properties of LSR are similar to the general purpose or medium high-strength peroxide cured elastomers. Other features such as oil and chemical resistance and electrical properties also follow the expected trend for silicone products. The LSR cure system generally results in the cured product being self-extinguishing, and with the inclusion of certain carbon black pigments will easily meet the requirements of the US Underwriters Laboratory flame test UL-94, with a class of V-O. 

As discussed in Chapter 10, a wide variety of additives is used in the polymer industry. Stabilizers, waxes, and processing aids reduce degradation of the polymer during processing and use. Dyes and pigments provide the many hues that we observe in synthetic fabrics and molded articles, such as household containers and toys. Functional additives, such as glass fibers, carbon black, and metakaolins can improve dimensional stability, modulus, conductivity, or electrical resistivity of the polymer. Fillers can reduce the cost of the final part by replacing expensive resins with inexpensive materials such as wood flour and calcium carbonate. The additives chosen will depend on the properties desired. 

Unlike other pigments, carbon black used in plastics processing not only yields coloristic effects but also modifies the electrical properties, provides heat and UV resistance, and may act as a filler to modify mechanical properties. 

To improve the properties of the raw polymer (wear resistance, creep resistance, thermal and electrical conductivity), various fillers, such as glass fibers, powdered metals, and graphite, are combined with all three types of PTFE polymers, mostly by intimate mixing. Filled fine powders are produced mostly by adding fillers into a dispersion and then coagulating the mixture. Aqueous dispersions can also be modified by the addition of certain fillers, pigments, heat resistant dyes, carbon blacks, and powdered metals, especially when processed into films (see Chapter 6). 

Carbon black Electrical conductivity, pigmentation, reinforcement, thermal conductivity, thermal resistance... 

Carbon blacks are extensively used in rubbers and elastomers, in loading from 10 to 150 phr, and for improvements in stiffness, strength, processability, and abrasion resistance (79). Particle size and concentration are optimized on the basis of balances in mixing-compounding, heat buildup, property improvement, and cost. Carbon black fillers, without considering the electrical conductive blacks, are used in plastics, predominantly as pigment or colorant. 

Carbon additives are used in polymer composites as fillers, reinforcing agents and pigments. In addition, carbon black is used to enhance UV stability, electrical conductivity and weather resistance. PP geotextiles containing carbon black are applied for soil reinforcement, filtration and other construction... 

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