Reinforcing black

The model in Figure 3.20a applies to ACM-silica, while Figure 3.20b suits the ENR-silica system. Kraus constant, C, determined from the slope of the plots in Figure 3.19, quantifies the mbber-silica interaction in these systems. CACM/siUca is 1-85 and CENR/siika is 2.30 and these values are significantly higher than the reinforcing black-filled mbber composites [65]. Hydrogen-bonded interaction between the SiOH and the vicinal diols in ENR is responsible for this, whereas dipolar interaction between ester and SiOH in ACM-silica only results in weaker adsorption of the mbber over the filler surfaces. 

FIGURE 26.46 Rate of cut growth for six different rubbers (O) gum rubber, (+) loaded with 20 pphr reinforcing black, and ( ) with 50 pphr reinforcing black. (From Lake, G.J. and Lindley, P.B., Rubber J., 146, 10, 1964.)... 

Reinforcing agents, adding to polyamide plastics, 29 780-781 Reinforcing blacks, 22 775 Reinforcing fillers, for silicone networks, 22 570, 571... 

Schematic drawings of some typical modem furnace black reactors are shown in Figure 50. They all have a gas-tight metal jacket. The reaction zone is coated with a ceramic inner liner, generally on an alumina base, which is stable to temperatures of ca. 1800 °C. Several quenching positions allow the changing of the effective volume of the reactor. This allows variation of the mean residence time of the carbon black at the high reaction temperature. Typical residence times for reinforcing blacks are 10-100 ms.

Figure 52. Typical energy balance for the manufacture of a reinforcing black...

The channel black process, used in the United States since the late 19th century, is the oldest process for producing small-particle-size carbon blacks on an industrial scale. Originally, the first reinforcing blacks were also produced by this process. In 1961, the production of channel black was about 120 000 t. The last production plant in the United States was closed in 1976, due to low profitability and environmental difficulties. Natural gas was used as the feedstock. The carbon black yield was only 3-6%. 

Most furnace black reactors are arranged horizontally. They can be up to 18 m long with an outer diameter of up to 2 m. Some vertical reactors are used especially for the manufacture of certain semi-reinforcing blacks (Figure 4.5) [4.12]. Further reactors are described in Ref. [4.13]. 

Later, some Japanese synthetic rubber scientists believed the attachment involved quinone groups that are on the surface of highly reinforcing blacks blocks. This was based on the work done with allyltin compounds, and was later shown to involve a concerted reaction of the allyltin end with an or /z6>-quinone structure that is present on the reactive Tin-coupled diene... 

An example of a much more heterogeneous surface is shown in Fig. 7.7. The adsorbent in this case is a carbon black designated C4, used by ASTM committee D24 as a reference reinforcing black. 

D. C. Larsen, J. W. Adams, H. H. Nakumara, Y. Harada, SiC-Reinforced Black Glass Matrix Composites, Report AFWAL-TR-88-43005, Materials Laboratory, Air Force Wright Aeronautical Laboratories, January 1989. 

Figure 10.1. Tensile stress-strain curves for four natural rubber compounds of different hardnesses 73 IRHD contains 50 parts of a reinforcing black, and different vulcanizing systems account for the different curves of the two gum compounds (47 and 33 IRHD). (Lindley, 1964.)...

A variety of dialkyl peroxides and tertiary butyl perbenzoate lead to high efficiency of cross-linking reactions in gum rubber, but only di-tertiary butyl and dicurnyl peroxides are capable of curing compounds containing reinforcing black fillers. Of these two, the former has the serious drawback of volatility, and hence very low efficiency. 

Figure 4.88 Stress vs. strain at various temperatures for BASF Petra 230 BK-112—35% mineral/glass fiber reinforced, black, injection molding, recycled PET resin [6].

Over 90% of carbon black production is consumed by the rubber processing industry as reinforcing black. The remaining 5 to 10% is used as pigments for paints, paper, printing inks and plastics. 

AU grades are frequently compounded with fiUer. A small amount of a reinforcing black or fumed silica can considerably improve tear strength and increase hardness. 

A key development in the carbon black reactor technology was the development of the zoned axial flow reactor for reinforcing blacks in the early 1960s (22). The reactor consists of three zones. The first zone is a combustion zone in which fuel and air are completely burned to produce combustion gases with excess oxygen. This gas flow is accelerated to high velocity in a throat zone with intense turbulent mixing. The feedstock is injected either into this throat zone or just... 

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. 

Donne developed ideas on the role of chemical interaction between saturated and unsaturated elastomers and carbon black and found that on the surface of highly reinforcing blacks, only 10% hydrogen atoms are reactive, and increased hydrogen content brings about a rise in the modulus of the rubber. Chemical and adsorption interaction with the surface of the carbon black leads to strong binding of the rubber. The fraction of bound rubber is determined by the gel content of the filler-rubber mixture the bound rubber content is proportional to the surface area. ... 

---