Rubbers, additives Carbon-blacks

RSS 2 was mixed with N-234 carbon black without additive or in the presence of quinonedihne, or with a peptizer (dibenzamidodiphenyl disulfide, activated with a metal chelate). In the case of the peptizer, rubber and carbon black were mixed for 30 s before the addition of carbon black. In the case of the quinone diimine, carbon black and QDI were added 15 s after addition of rubber to the mixer. 

The emphasis is on commercial materials and formulations. The reason is that commercial materials are rarely pure materials. A pure homopolymer is a rare species in the real-world materials. To arrive at the desired material s properties, either a copolymer is used, sometimes a blend or a dispersion, or additives or filler materials including rubber particles, carbon black or fibres of various type and make may be added, and are thus commonplace in commercial products. This implies a more complex constitution and morphology than expected for pure polymers. However, obviously, the methods described herein can be applied to pure, unmodified, polymers as well. 

The tinting strength of rubber-grade carbon blacks shows a linear relationship with D s shown in Figure 5. Since performance characteristics are known to depend on aggregate volume, surface area, and bulkiness, it appears that the D s values combine the effects of all these factors. As such, it is a valuable addition to carbon black characterization methodology. 

When a sinusoidal strain is imposed on a linear viscoelastic material, e.g., unfilled rubbers, a sinusoidal stress response will result and the dynamic mechanical properties depend only upon temperature and frequency, independent of the type of deformation (constant strain, constant stress, or constant energy). However, the situation changes in the case of filled rubbers. In the following, we mainly discuss carbon black filled rubbers because carbon black is the most widespread filler in rubber products, as for example, automotive tires and vibration mounts. The presence of carbon black filler introduces, in addition, a dependence of the dynamic mechanical properties upon dynamic strain amplitude. This is the reason why carbon black filled rubbers are considered as nonlinear viscoelastic materials. The term non-linear viscoelasticity will be discussed later in more detail. 

When the behavior of carbon black and silica is compared in compounded rubber, it is evident that silica adsorbs less rubber than carbon black. In addition to the differences in the chemical compositions of the surfaces this difference is caused by the differences in the dispersive components of surface energies of each filler. Car-... 

Reinforcing Agents. To increase the cohesive strength of an unsaturated rubber adhesive, carbon black is the material of choice. It must be added to the rubber in an internal mixer or on a two roll mill before the rubber is dissolved in the solvent. Such additions do, of course, stiffen the dried adhesive, and some softener may be required to balance this, though this could adversely affect adhesive performance. Carbon black used to be added by means of whole tire reclaim but, as noted in the introduction, the practice is declining. 

GRT particles are also compositionally quite complex. Tires contain a number of different rubbers (SBR, butyl rubber, natural rubber, polybutadiene rubber etc.), carbon black filler, antioxidants, and additional additives, the exact composition depending on the t3q)e of tire and the part of the tire (e.g. tread vs. side-wall, vs. liner). Elementally, a t3q)ical tire is comprised of carbon 83%, hydrogen 7%, ash 6%, oxygen 2.5%, sulfur 1.2%, and nitrogen 0.3%. There is approximately 45-55% rubber hydrocarbon, 10-15% acetone extractables, 20-30% carbon black, and 6% ash. ... 

Where the polymer must be mixed with other materials, the process of master batching sometimes allows this to be done conveniently and uniformly. In rubber technology, carbon black and oil are emulsified and mixed with the rubber latex and then the mixture is coagulated together, giving a uniform and intimate dispersion of the additives in the rubber. 

Carbon black is a universal reinforcing filler and light stabilizer used in rubber compounds. Carbon black imparts strength and toughness to a tire as well as it improves the rubber s resistance to tearing, abrasion, flex fatigue and also increases traction and durability. A tire would last less than 5000 miles without the addition of carbon black. 

Stretching a polymer sample tends to orient chain segments and thereby facilitate crystallization. The incorporation of different polymer chains into small patches of crystallinity is equivalent to additional crosslinking and changes the modulus accordingly. Likewise, the presence of finely subdivided solid particles, such as carbon black in rubber, reinforces the polymer in a way that imitates the effect of crystallites. Spontaneous crystal formation and reinforcement... 

Nitrile Rubber. Vulcanized mbber sheets of NBR and montmorillonite clay intercalated with Hycar ATBN, a butadiene acrylonitrile copolymer have been synthesized (36). These mbber hybrids show enhanced reinforcement (up to four times as large) relative to both carbon black-reinforced and pure NBR. Additionally, these hybrids are more easily processed than carbon black-filled mbbers. 

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. 

For very many years it has been common practice to improve the electrical conductivity of plastics and rubbers by the incorporation of certain additives like special grades of carbon black. Such materials were important, for example, in hospital operating theatres where it was essential that static charges did not build up, leading to explosions involving anaesthetics. 

Carbon black is an extremely fine powder of great commercial importance, especially for the synthetic rubber industry. The addition of carbon black to tires lengthens its life extensively by increasing the abrasion and oil resistance of rubber. 

A thin layer of a mix of natural rubber, sulfur, precipitated silica, water, and some additives, such as carbon black and vulcanizing agents, is extruded on a paper support belt, calendered, and vulcanized as a roll in an autoclave under elevated pressure and temperature ( 180 °C). A modi-... 

The purpose of this report is to bring the author s model and theory for carbon black reinforcement of rubbers to a conclusion, with additional experiments and discussion. This research consists of three papers (Part 1, Part 2, and Part 3), where the reinforcement of elastomers is generalized with the universal and common concept. Now, preceding the detailed discussion, we would like to discuss the previous concept generally accepted for carbon black reinforcement of rubbers and the author s new model and theory. 

Figure 18.1 is the typical stress-strain curves of the filled rubber (SBR filled with fine carbon black, HAF),

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