Rubbers, synthetic

In addition to natural rubber, synthetic rubbers can be utilised in many forms. 

The first polymerization of isoprene in sealed bottles was reported in 1884 by Tilden. Methyl rubber was thermally polymerized at 70 °C - the reaction 

The first commercially successful synthetic polymer was phenol-formaldehyde (PF) resin (Smith 1899). The resin was introduced in 1909 by Baekeland as Bakelite . The urea-formaldehyde (UF) resins were discovered in 1884, but production of Beetle moldable resin commenced in 1928. Three years later, Formica , phenolic paper covered with decorative layer protected by UF, was introduced. The thiourea-formaldehyde molding powders were commercialized in 1920, while in 1935, Ciba introduced Cibanite , aniline-formaldehyde (AF) resins, molding materials, and then, 2 years later, the melamine formaldehyde (MF). 

Epoxy compounds were discovered by Prileschaiev in 1909, but its importance was realized only during WW2. In 1956, glass fiber reinforcements were introduced. The thermoset polyesters (TS) were developed by Ellis in 1933-1934. The first use of glass-reinforced TS dates from 1938. 

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Emulsion polymerisation of a mixture of butadiene and styrene gives a synthetic rubber (Buna S GBS rubber), which is used either alone or blended with natural rubber for automobile tyres and a variety of other articles. 

It is of interest to note that synthetic rubbers are produced by the polymerisation of dienes and are therefore examples of additive polymerisation. Thus ... 

Organic chemistry demands much from chlorine, both as an oxidizing agent and in substitution, since it often brings many desired properties in an organic compound when substituted for hydrogen, as in one form of synthetic rubber. 

The hydrocarbon shown called vmylacetylene is used in the syn neoprene a synthetic rubber Identify the orbital overlaps involved in How many cr bonds are there in vmylacetylene How many... 

The use of 1 3 butadiene in the preparation of synthetic rubber is discussed in the boxed essay Diene Polymers that appears later in this chapter... 

The conjugated diene 1 3 butadiene is used m the manufacture of synthetic rubber and IS prepared on an industrial scale m vast quantities Production m the United States is currently 4 X 10 Ib/year One industrial process is similar to that used for the prepara tion of ethylene In the presence of a suitable catalyst butane undergoes thermal dehy drogenation to yield 1 3 butadiene... 

As described in the box Di ene Polymers in Chapter 10 most synthetic rubber is a copolymer of styrene and 1 3 butadiene... 

Synthetic Rubbers. Synthetic rubbers are polymers with rubberlike characteristics that are prepared from dienes or olefins. Rubbers with special properties can also be prepared from other polymers, such as polyacrylates, fiuorinated hydrocarbons, and polyurethanes. 

Chlorine Ammonia, acetylene, alcohols, alkanes, benzene, butadiene, carbon disulflde, dibutyl phthalate, ethers, fluorine, glycerol, hydrocarbons, hydrogen, sodium carbide, flnely divided metals, metal acetylides and carbides, nitrogen compounds, nonmetals, nonmetal hydrides, phosphorus compounds, polychlorobi-phenyl, silicones, steel, sulfldes, synthetic rubber, turpentine... 

An important application of Eq. (3.39) is the evaluation of M, . Flory et al.t measured the tensile force required for 100% elongation of synthetic rubber with variable crosslinking at 25°C. The molecular weight of the un-cross-linked polymer was 225,000, its density was 0.92 g cm , and the average molecular weight of a repeat unit was 68. Use Eq. (3.39) to estimate M. for each of the following samples and compare the calculated value with that obtained from the known fraction of repeat units cross-linked ... 

Synthetic polymers Synthetic Processes Synthetic pyridine Synthetic rubber... 

Synthetic rubbers Synthetics Synthetic silicates Synthetic surfactants Synthetic tanning agents... 

Rubber. Both natural and synthetic rubber are used as bonding agents for abrasive wheels. Rubber-bond wheels are ideal for thin cut-off and slicing wheels and centerless grinding feed wheels. They are more flexible and more water-resistant than resinoid wheels. 

Elastomers. Elastomers are polymers or copolymers of hydrocarbons (see Elastomers, synthetic Rubber, natural). Natural mbber is essentially polyisoprene, whereas the most common synthetic mbber is a styrene—butadiene copolymer. Moreover, nearly all synthetic mbber is reinforced with carbon black, itself produced by partial oxidation of heavy hydrocarbons. Table 10 gives U.S. elastomer production for 1991. The two most important elastomers, styrene—butadiene mbber (qv) and polybutadiene mbber, are used primarily in automobile tires. 

M. J. Rhoad, Proceedings ofithe 15th Annual Meeting International Institute of Synthetic Rubber Producers, Inc., Kyoto, Japan, 1974 Pubberlnd. (Eondon) 9(12), 68 (1975) Pubber Plast. News, 14 (fan. 23, 1978). 

See Latbx tbchnology Elastomers, synthetic Rubber chemicals. 

Speciali dElastomers bulletins, Eirestone Synthetic Rubber Latex Co., Akron, Ohio. 

P. M. Norling, "Managing Technology Critical Questions for the Synthetic Rubber Industry," 29th Mnnual Meeting International Institute of Synthetic... 

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