Vulcanization definition

There is a definite trend in the suppHer industry to develop multifimctional materials with value-added properties. One suppHer has introduced a modified hydrocarbon resin that softens, improves filler incorporation, improves mill banding, and increases tack in the green compound while imparting increased low strain (<100%) stiffness, significantly improving tear resistance in the vulcanized compound. 

Each type of rubber has a definite range of temperatures which may be used for vulcanization. These temperatures may vary somewhat, but it is quite important not to exceed the maximum for each since some form of deterioration will occur. This effect is either shown by the appearance of the finished product or by its physical properties. 

Rubber - An elastomer, generally implying natural rubber, but used loosely to mean any elastomer, vulcanized and unvulcanized. By definition, a material that is capable of recovering from large deformations quickly and forcibly. 

Early work in this field was conducted prior to the availability of powerful radiation sources. In 1929, E. B. Newton "vulcanized" rubber sheets with cathode-rays (16). Several studies were carried out during and immediately after world war II in order to determine the damage caused by radiation to insulators and other plastic materials intended for use in radiation fields (17, 18, 19). M. Dole reported research carried out by Rose on the effect of reactor radiation on thin films of polyethylene irradiated either in air or under vacuum (20). However, worldwide interest in the radiation chemistry of polymers arose after Arthur Charlesby showed in 1952 that polyethylene was converted by irradiation into a non-soluble and non-melting cross-linked material (21). It should be emphasized, that in 1952, the only cross-linking process practiced in industry was the "vulcanization" of rubber. The fact that polyethylene, a paraffinic (and therefore by definition a chemically "inert") polymer could react under simple irradiation and become converted into a new material with improved properties looked like a "miracle" to many outsiders and even to experts in the art. More miracles were therefore expected from radiation sources which were hastily acquired by industry in the 1950 s. 

The good definition of these systems implies that the models of sec. 2.4 apply. Kern and Flndenegg ) fitted the experimental results for the adsorption of n-docosane from n-heptane on Vulcan 3G graphite at 25, 35 and 45°C with 12.4.34b] assuming 0 and r = 2.67. A good fit was obtained with a lateral Interaction parameter 2° of 1.16, 1.10 and 0.91 and equilibrium constants of 13.9, 10.6 and 8.2 for the three temperatures, respectively. The standard enthalpy of displacement of r moles of n-heptane by 1 mole of n-docosane was calculated from the temperature dependence of K. The value of -54.4 kJ mole obtained compared very well with the calorimetric result at monolayer coverage, -58.8 kJ mole L... 

Vulcanization.—The most important treatment of rubber, in the process of converting it into a technically valuable product, is that known as vulcanization. This consists in the addition of sulphur which produces a very definite change in properties. The sticky or adhesive character of pure caoutchouc is entirely lost and it becomes very elastic and does not set when stretched. Even with wide range in temperature it neither hardens nor softens and it becomes insoluble in caoutchouc solvents. The presence of sulphur, usually in small... 

In addition to cellulosic and synthetic resins, the present scope of the industry includes vulcanized fiber, casein pla dcs, and regenerated cellulose. This definition has evolved over a period of years. 

There is a definite difference in elastic behavior between linear and cross-linked rubbers. A sample of a cross-linked, or vulcanized, rubber is... 

By definition, cross-linking involves the formation intermolecular connections through chemical bonds. This process necessarily results in reduction in chain mobility. Consequently, Tg increases. For lightly cross-linked systems like vulcanized rubber, Tg shows a moderate increase over the uncross-linked polymer. In this case, Tg and the degree of cross-linking have a linear dependence, as shown by the following approximate empirical equation. 

Definition Elastomer based on stereospecific linear terpolymers of ethylene, propylene, and diene vulcanized by sulfur or peroxide crosslinking ... 

Definition Prod, of chlorosulfonation of a carbon tetrachloride solution of polyethylene with chlorine and sulfuryl chloride elastomer used in vulcanized and unvulcanized form vulcanizates have exc. oil/chemi ozone/weather resist. 

Classification Epichlorohydrin elastomer Definition Vulcanized with sulfur or peroxides vulcanizates have good heat/weather/flame/oil resist, exc. low temp, props. 

Synonyms BIIR Brominated butyl rubber Brominated isobutylene/isoprene copolymer Bromobutyl rubber 1,3-Butadiene, 2-methyl-, polymer with 2-methyl-1-propene, brominated Butyl rubber, brominated Isobutylene, isoprene polymer, brominated Definition Elastomer vulcanized by sulfur systems vulcanizate offers low gas permeability, good weather/ozone resist., better chem./heat resist, than butyl rubber... 

Definition Polyoxyethylene, polyoxypropylene block polymer of ethylene diamine Properties Nonionic Toxicoiogy TSCA listed Uses Emulsifier, thickener, wetting agent, dispersant, solubilizer, stabilizer in cosmetics, pharmaceuticals demulsifier in petrol, industry detergent ingred. antistat for polyethylene and resin molding powds. polymerization in latex-based paints, aq.-based syn. cutting fluids and vulcanization of rubber... 

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