Liquid Ebonite

However, for construction purposes, solid ebonites were chosen. As is known from rubber chemistry, solid ebonite, commonly known as hard rubber, is a polymer material with sulfur content used for vulcanization. Ebonite, like elastomeric or flexible rubber, is made from a combination of sulfur with polydienes (unsaturated rubbers containing double bonds). The sulfur and polydienes are combined with some auxiliary additives and heated to produce vulcanization. Typical mass ratios of sulfur to rubber are 2 100 for elastomeric rubber and 40 100 for hard rubber. Due to the large degree of sulfide cross linking formed in the vulcanization process, solid ebonite is a hard, non-flexible, plastic-like material possessed of 

The elastic modulus of ebonite in its high elastic stage (i.e., at high temperature) is some ten times that of a pure gum soft vulcanized 

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Figovsky, O., and Blank, N. Liquid Ebonite Mixtures for Anticorrosive Coverings, International Conference Corrosion in Natural and Industrial Environments Problems and Solutions, Grado, Italy, May 23-25, 1995, 593-599. 

Ebonite has a good resistance to a range of inorganic liquids, including most non-oxidising acids. It is severely swollen by aromatic and chlorinated hydrocarbons. 

The diffusion of water into a mass of ebonite is so slow that the water absorbed affects only the material at the surface. In practice the degree of absorption would require many months or even years to complete on continuous exposure to water or dilute liquids. 

You have two liquids, A and B. You know that one liquid contains polar molecules, and the other liquid contains non-polar molecules. You do not know which is which, however. You pour each liquid so that it falls in a steady, narrow stream. As you pour, you hold a negatively charged ebonite rod to the stream. The stream of liquid A is deflected toward the rod. The rod does not affect the stream of liquid B. Which liquid is polar Explain your answer. 

E (Fig. 3. VIII F) and a copper disc, both 7 cm. diam., the internal diain. of the ebonite ring being 3-7 cm. The liquid filled the space between the copper discs L and M. The temperature difference between U and M was measured, and since the conductivity of the ass was known, the heat entering M coidd be... 

The swelling time of ebonite is usually greater than (10-15 times) that for soft rubber in the same liquid. Carbon disulfide is an exception since it swells ebonite almost as quickly as soft rubber. Moreover with ebonite there are greater differences between the swelling times of different liquids than with soft rubber. 

With soft rubber the swelling time is generally shorter, the less viscous the liquid, but this relationship does not apply to ebonite through which the least viscous liquids like acetone ethyl acetate and petroleum ether, diffuse slowly. 

Therefore, although the viscosity of a liquid does influence its rate of penetration into ebonite, the permeability of the ebonite is so greatly increased by absorption of the liquid that its swelling capacity has much more influence on this rate rather than the viscosity itself. It may be useful to understand at this juncture what permeability of a rubber or ebonite is to gases or liquids. 

The rate of diffusion in a given elastomer is found to be related chiefly to the size of the liquid/gases molecule. It is observed that the presence of polar group or methyl group in the polymer molecules reduces the permeability to a given liquid/gas. Therefore butyl, Neoprene and nitrile, along with ebonite, have a low value of permeability when compared with natural soft rubber vulcanisates. 

Poisson s ratio is a measure of the reduction in the cross section accompanying stretching and is the ratio of the transverse strain (a contraction for tensile stress) to longitudinal strain (elongation). Poisson s ratio for many of the more brittle plastics such as polystyrene, the acrylics, and the thermoset materials is about 0.3 for the more flexible plasticized materials, such as cellulose acetate, the value is somewhat higher, about 0.45. Poisson s ratio for rubber is 0.5 (characteristic of a liquid) it decrease to 0.4 for vulcanized rubber and to about 0.3 for ebonite. Poisson s ratio varies not only with the nature of the material but also with the magnitude of the strain for a given material. All values cited here are for zero strain. 

Although a metering piston constructed in this manner has a density approximately four times greater than the ebonite piston used conventionally, the pressure drop through the meter when running in liquid oxygen was found to be very similar to that of a meter designed for use of water, i.e., psi at 50 maximum flow. 

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