Tires Thermal black

FIGURE 26.44 Abrasion loss as function of pressure for four different compounds. A SBR + 50 HAF black, B NR + 50 HAF black, C NR + 50 thermal black, D NR + 50 activated CaCOs. (From Schallamach, A. and Grosch, K.A., The Mechanics of Pneumatic Tires, S.K. Clark (ed.), The US Department of Transportation, National Highway Safety Administration, Washington DV, p. 407.)... 

Specific Surface Area. The specific surface area of industrial carbon blacks varies widely. While coarse thermal blacks have specific surface areas as small as 8 m2/g, the finest pigment grades can have specific surface areas as large as 1000 m2/g. The specific surface areas of carbon blacks used as reinforcing fillers in tire treads lie between 80 and 150 m2/g. In general, carbon blacks with specific surface areas >150 m2/g are porous with pore diameters of less than 1.0 nm. The area within the pores of high-surface-area carbon blacks can exceed the outer (geometrical) surface area of the particles. 

The solar-thermal process is enviromnentally friendly. The most environmentally friendly option is when selling carbon black into the tire carbon black market as the energy and pollution associated with normal carbon black production are avoided. If carbon is fed to a carbon conversion fuel cell, the total green house gas emissions are still 60% of those of a steam reformer and the bulk of the released CO2 is in a pure form so it can be easily sequestered. 

Pyrolysis of scrap tires was studied by several mbber, oil, and carbon black industries [14]. Pyrolysis, also known as thermal cracking is a process in which polymer molecules are heated in partial or total absence of air, until they fragment into several smaller, dissimilar, random-sized molecules of alcohols, hydrocarbons, and others. The pyrolysis temperature used is in the range of 500°C-700°C. Moreover, maintenance of partial vacuum during pyrolysis in reactors lowered the economy of the process. Several patents were issued for the pyrolysis of worn out tires to yield cmde oil, monomers, and carbon black in economic ways [15-18]. The major drawback of chemical recycling is that the value of the output is normally low and the mixed oils, gases, and carbon black obtained by pyrolysis cannot compete with similar products from natural oil. Pyrolyzing plant produces toxic wastewater as a by-product of the operation [19]. 

Carbon black includes several forms of artificially prepared carbon, such as furnace black, channel black, lamp black, and animal charcoal. It is a finely divided form of carbon consisting of particles of extremely fine size. It is obtained by partial combustion (in 50% required air) of vapors of heavy oil fraction of crude oil in a furnace or by thermal cracking of natural gas. Carbon black is used in many abrasion-resistant rubber products including tire treads and belt covers. It also is used in typewriter ribbons, printing inks, carbon paper, and paint pigments. It also can be an absorber for solar energy and UV radiation. 

In the depolymerized scrap mbber (DSR) experimental process, ground scrap mbber tires produce a carbon black dispersion in oil (35). Initially, aromatic oils are blended with the tire crumb, and the mixture is heated at 250—275°C in an autoclave for 12—24 h. The oil acts as a heat-transfer medium and swelling agent, and the heat and oil cause the mbber to depolymerize. As more DSR is produced and mbber is added, less aromatic oil is needed, and eventually virtually 100% of the oil is replaced by DSR. The DSR reduces thermal oxidation of polymers and increases the tack of uncured mbber (36,37). Depolymerized scrap mbber has a heat value of 40 MJ/kg (17,200 Btu/lb) and is blended with No. 2 fuel oil as fuel extender (38). 

Time-Resolved Laser-Induced Incandescence (by Prof. Alfred Leipertz et al.) introduces an online characterization technique (time-resolved laser-induced incandescence, TIRE-LII) for nano-scaled particles, including measurements of particle size and size distribution, particle mass concentration and specific surface area, with emphasis on carbonaceous particles. Measurements are based on the time-resolved thermal radiation signals from nanoparticles after they have been heated by high-energetic laser pulse up to incandescence or sublimation. The technique has been applied in in situ monitoring soot formation and oxidation in combustion, diesel raw exhaust, carbon black formation, and in metal and metal oxide process control. 

Carbon black [1333-86-4] is virtually pure elemental carbon (diamond and graphite are other forms of nearly pure carbon) in the form of near-spherical colloidal particles that are produced by incomplete combustion or thermal decomposition of gaseous or Uquid hydrocarbons. Its physical appearance is that of a black, finely divided pellet or powder, the latter sometimes small enough to be invisible to the naked eye. Its use in tires, mbber and plastic products, printing inks and coatings is related to the properties of specific surface area, particle size and structure, conductivity and color. 

A 6-ra-intemal diameter spherical rank made of l.5outer surface of the lank is black (emissivity e = 1), and heal transfer between the outer surface of the tank and the surroundings is by natural convection and radiation. Assuming the entire steel tank lo be al 0°C and thus the thermal resistance of tire lank to be negligible, detenninc (n) the rate of heal transfer to the iced water in the lank and (b) the amount of ice at 0°C that melts during a 24-h period. The heat of fusion of water is 333.7 kJ/kg Ansf/ers (a) 15.4 kVt, (b) 3988 kg... 

Carbon blacks (c.b.s) have been known since ancient times, for preparing Indian ink. From the 1920s, c.b. has been fabricated industrially on a large scale by the thermal decomposition of hydrocarbons (natural gas) or aromatic hydrocarbons. Of the total production, 90% goes into the rubber industry, and most of this is employed for the reinforcement of tires. Production capacity is at present 7.2 million tonnes/y and the armual production is 6.1 million tormes/y [244] 95% of this global fabrication is by the furnace c.b. process [245]. The specific surface area As (nr/g) in this case covers a range from a few tens up to more than 1500. It should be mentioned that c.b. is used as a filler for conducting polymers [246]. 

Pyrolysis of scrap tires gives as major products, gas, oil, and residue. The gas is the result of thermal cracking and dehydrogenation. The oil derives from extender oils used in the compounding of the vulcanizates as well as from the depolymerization fragments from the rubber. The residue represents recovered carbon black as well as any inorganic material used in the fabrication of the original rubber. 

Silica-filled tread compounds for passenger car tires have become state-of-the-art and have taken a significant share from conventional carbon black-filled systems. In addition to the well-known benefits of fillers such as reinforcement (Fig. 11) and increased cut resistance, silica-based compounds are mainly successful because they provide improved rolling resistance (leading to lower fuel consumption), better wet and snow track resistance, and thermal stability. 

A significant use of acetylene black is in dry cell batteries where it contributes low electrical resistance and high capacity. In rubber it gives electrically conductive properties to heater pads, tapes, antistatic belt drives, conveyor belts, and shoe soles. It is also useful in electrically conductive plastics such as electrical magnetic interference (EMI) shielding enclosures. Its contribution to thermal conductivity has been useful in rubber curing bags for tire manufacture. 

The main drawbacks of TPEs compared with conventional rubber are the relatively high cost, the general inability to load TPEs with low-cost fillers (for example, carbon black, preventing their use in automobile tires), low chemical and heat resistance, high compression set, and poor thermal stability. 

Carbon black is now mainly manufactured by thermal decomposition, by dehydrogenation, or by partial oxidation of aromatic petroleum hydrocarbons. Graphon (Cabot Corporation) is produced by heat treatment of Spheron 6 carbon at very high temperatures to remove oxygen-containing surface groups and to increase ordering of layers. The major use of carbon black is in the manufacture of rubber for tires. Other uses are in inks and in batteries. 

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