Compounding conductive rubbers

Rubber so compounded as to produce a vulcanisate having an electrical resistivity of about 107 to 109 ohm-cm. See Conductive Rubber. 

N. Prost, Conductive Rubber Compounds—Compounding with Extra-Conductive Carbon Black, Phillips Petroleum Chemicals Bulletin, June 1985. 

R. R. Juengel, Carbon Black Selection for Conductive Rubber Compounds, Paper No. 78, Rubber Division, ACS Meeting, Los Angeles, Calif., Apr. 1985. 

Acrylic acid, zinc salt Ageflex ZDA EINECS 238-692-3 2-Propenoic acid, zinc salt Zinc acrylate Zinc dlacrylate. Crosslinker for molded polybutadiene compounds, conductive and protective coatings, coagent for SBR compounds and reactive pigments activator for rubber compounding scorch retarder. Rit-Chem. 

Friction materials. Brake linings and clutch facings use 2 percent of the phenolic resin market. The resin is compounded with rubber for toughness mica, talc, and glass for friction and powdered metal for thermal conductivity to prevent over-heating. 

AH, Z., Le, H.H., Ilisch, S., and Radusch, H.J. (2009) Morphology development in nanoclay filled rubber compounds and rubber blends detected by online measured electrical conductance. J. Mater. Sd., 44, 6427. 

For the purpose of studying of influence of structural parameters of NR samples processed in various temperature time intervals on properties of rubber compounds and rubbers on their basis, within the standard filled compounding for NR [5] rubber mixes were made and their vulcanizing properties and physicomechanical properties of vul-canizers were defined. Results of the conducted researches are given in Table 10.2. 

In our experiments with an electrically conductive rubber compound, a steady current flow has been observed when a D.C. potential is applied across the contacting bodies. The rise time of the current, if any, was not noticable. It may be concluded... 

Between the 1920s when the initial commercial development of mbbery elastomers based on 1,3-dienes began (5—7), and 1955 when transition metal catalysts were fkst used to prepare synthetic polyisoprene, researchers in the U.S. and Europe developed emulsion polybutadiene and styrene—butadiene copolymers as substitutes for natural mbber. However, the tire properties of these polymers were inferior to natural mbber compounds. In seeking to improve the synthetic material properties, research was conducted in many laboratories worldwide, especially in the U.S. under the Rubber Reserve Program. 

For many years it has been common practice to improve the electrical conductivity of plastics and rubbers by incorporating certain additives, such as special grades of carbon black. Such compounds have been important, for... 

Above a critical hller concentration, the percolation threshold, the properties of the reinforced rubber material change drastically, because a hller-hUer network is estabhshed. This results, for example, in an overproportional increase of electrical conductivity of a carbon black-hUed compound. The continuous disruption and restorahon of this hller network upon deformation is well visible in the so-called Payne effect [20,21], as represented in Figure 29.5. It illustrates the strain-dependence of the modulus and the strain-independent contributions to the complex shear or tensUe moduli for carbon black-hlled compounds and sUica-hUed compounds. 

The thermal conductivity of compounded rubber is an additive property of the rubber and the compounding ingredients, and may be calculated from the mix formula and the individual thermal conductivities. 

An activator in rubber compounds containing organic accelerators. In polychloroprene, zinc oxide is considered to be the accelerator rather than the activator. The use of zinc oxide as a reinforcing agent and as a white colouring agent is obsolescent. Zinc oxide is manufactured by either the French (or indirect) process or by the American (or direct) process. It can be used as a filler to impart high thermal conductivity. 

The development and optimisation is described of a new curing system to replace lead-based compounds used in epichlorohydrin elastomers currently used in automotive applications. The system is based on 2,4,6-trimercapto-1,3,5-triazine and dialkyldithiophosphate, which is shown to produce a scorch-safe curing system and which confers excellent physical and ageing properties on epichlorohydrin rubbers. Trials are conducted in formulations for multilayer fuel hoses. 9 refs. 

In the electrode with CuS alone, which has negligible conductivity, the precipitate ISE with a silicone rubber matrix has better properties than the electrode with a pressed pellet [314], The ISE with a mixture of CuS and Agi S finds broad application [325]. If the membrane is prepared by pressing, the grains of these two compounds combine to form jalpaite, Agi.55C%.4sS [180], This substance is a mixed conductor with transport numbers of Ag, 0.69 Cu(I), 0.30 and electrons, 0.01, at 25 C [175]. The sintered electrode also contains Ag1.2Cuo.8S or Ago.93Cu1.07S. Oxidation of these phases leads to considerable deterioration in the electrode function [180]. Good electrodes... 

Occupational exposure to 1,3-DNB and 1,3,5-TNB can occur when workers handle the compounds in explosives plants and other industries, such as dyestuffs, plastics, and rubber, that use these compounds during manufacturing processes. The National Occupational Exposure Survey (NOES), conducted by NIOSH from 1981 to 1983, estimated that 2,489 workers were exposed to 1,3-DNB in 41 businesses and health services (NOES 1991). The workers included in this survey were chemists (except biochemists), geologists, clinical laboratory technologists and technicians, and health aides (except nursing). 

Researchers at Lehigh University have investigated the ability of ground tire rubber to sorb organic compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) to determine the feasibility of using the rubber as the sorbent media in reactive permeable barrier systems. Thus far, no field-scale work has been performed on this technology. Both batch and packed-bed column tests have been conducted. All information is from the researchers and has not been independently verified. 

Overcuring is encountered to some degree in all compounds of any thickness because of the slow conductance of heat through rubber. Earthmover tires may have tire shoulder gauges in excess of 0.3 m (M2 in.). The outside/inside are overcured to effect a satisfactory state-of-cure in the tread rubber. 

It has also been suggested however, that even with well-separated aggregates of carbon black, flocculation may occur by diffusion in a hot rubber compound, contributing to the formation of a network and an electrically conducting structure. 

An example of this type of a safer chemical is methacrylonitrile (1) compared with acrylonitrile (2) (Figure 1.1). Both compounds are a, 3-unsaturated aliphatic nitriles, and structurally very similar, but 2 causes cancer whereas 1 does not appear to do so. Among other applications, 2 is used in the production of acrylic and modacrylic fibers, elastomers, acrylonitrile-butadiene-styrene and styrene-acrylonitrile resins, nitrile rubbers, and gas barrier resins. In a study conducted by the US National Toxicology Program (NTP) in which 2 was administered orally to mice for 2 years, there was clear evidence that it caused cancer in the treated mice (in addition to causing other toxic effects), and is classified by the NTP as a probable human carcinogen [26]. 

Another process for improving the bromination efficiency in rubber bromination processes is to conduct the reaction in the presence of elemental bromine and an aqueous solution of an organic azo compound such as 2,2 -azobisisobutyronitrile and sodium hypochlorite, potassium hypochlorite, or magnesium hypochlorite (42,43). 

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