Carbon black reinforcement factor

The tire is a complicated composite product consisting of tread, undertread, carcass, innerliner, bead, and sidewall. Many different types of rubber and carbon black reinforcement are used in manufacturing tires. Therefore, GRT is a blend of various rubbers and carbon blacks. Accordingly, in using GRT powder and devulcanized GRT in new tire manufacturing, many factors should be considered. Evidently, scrap tire powder can be used as a filler for virgin rubbers and devulcanized GRT can be used in blends with virgin rubbers. This market consumed approximately 1.354 x 10 tons of scrap tire rabber in 2009 (US Scrap Tire Markets, 2009). 

It can be seen that, with regard to the pure matrix, the elastic modulus, tensile strength and strain at break increase with nanotube loading. On the other hand, the addition of 10 MWNTs impart to the matrix a higher level of reinforcement than 10 phr of carbon black. Many factors could potentially explain the superior reinforcing efficiency of carbon nanotubes and among them, the filler aspect ratio is expected to play an important role in the mechanical response of the composite. Experimental data can be usefully compared to theoretical model predictions, especially those of Guth [71] and Halpin-Tsai [72]. 

The furnace process involves injecting low end fraction of cmde oil, eg. Bunker Euel 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 si2e and stmcture. The particle si2e and stmcture 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 appHcations, and other uses. 

Thermal stability is a crucial factor when polysaccharides are used as reinforcing agents because they suffer from inferior thermal properties compared to inorganic fillers. However, thermogravimetric analysis (TGA) of biocomposites suggested that the degradation temperatures of biocomposites are in close proximity with those of carbon black composites (Table-1). 

Silica compounds are generally processed in conventional internal mixers, preferably with intermeshing rotors. These mixers are designed and optimized for carbon black-fiUed compounds in which mixing is based only on physical processes. When a silica-silane reinforcing system is used, additionally a chemical reaction, the sUanization, occurs. One of the main influencing factors of the silanization reaction is the concentration of ethanol in the compound as well as in the mixer [25,26]. As the silanization finally reaches an equilibrium, low concentrations of ethanol in the compound are expected to enhance the reaction rate. 

For carbon-black fillers, structure, particle size, particle porosity, and overall physico-chemical nature of particle surface are important factors in deciding cure rate and degree of reinforcement attainable. The pH of the carbon black has a profound influence. Acidic blacks (channel blacks) tend to retard the curing process while alkaline blacks (furnace blacks) produce a rate-enhancing effect in relation to curing, and may even give rise to scorching. 

Another important factor is the particle size of the carbon black filler. The smaller the particle size, the higher the reinforcement, but the poorer the processability because of the longer time needed for dispersion and the greater heat produced during mixing. Blacks of the smallest particle size are thus unsuitable for use in rubber compounding. 

Any one of several factors may be responsible for the reinforcement effect of active fillers. Some fillers can contract chemical bonds with the material to be reinforced. In the case of carbon black, this takes place by means of the radical reactions of the unpaired electrons, which are present in large numbers of carbon black. Carbon black particles cause cross-linking in elastomers. 

The use of carbon black as a reinforcing filler for tire treads started back in 1918. The effect of the reinforcing by carbon black is not clear enough. It is known that the factors irrfluencing the reirrforcement are as follows ... 

The extent of reinforcement produced by the carbon black is affected by factors such as (i) particle size, (ii) structure, (iii) physical nature of the surface and (iv) degree of filler dispersion in the rubber matrix. 

Another key factor in governing the reinforcement efficiency of filler is its surface area. Ideally, the dispersion of silica in NR-silica composite should be as homogeneous as possible and less silica-silica interaction. This chapter will focus on NR-silica nanocomposites obtained through various approaches as reported in the literature. It is worth noting that from the aspect of sustainable development, NR-silica nanocomposite provides the opportunity for greener products where carbon black is either totally or partially replaced by silica. 

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