Natural rubber also

The French word for rubber, formerly used to denote highly purified natural rubber, also termed rubber hydrocarbon. 

Although helical structures dominate the structural hierarchies found in proteins, random chain structures similar to those found in natural rubber also are found in tissues. The most-studied random chain polymer found in vertebrate tissues is elastin. 

Thermoplastic Elastomers Thermoplastic Elastomers are a very flexible type of thermoplastic that has the properties of natural rubber. Also called TPE. 

Classification Thermoplastic elastomer Definition Polymer of isoprene major component of natural rubber, also made synthetically avail, in range of std., oil-extended and carbon bik.-filled grades props, vary with catalysts used in mfg. (lithium, titanium)... 

Non-reinforcing fillers, for a given increase in vulcanizate stiffness, generally give better permanent set, creep and dynamic properties than reinforcing types. The basic properties of natural rubber also show up to advantage in the fabrication of components. 

Clay platelets can be more easily dispersed in polar polymers than in nonpolar polymers like natural rubber because of their hydrophilic nature. Natural rubber also consists of longer polymeric chains than most thermoplastics, and so the penetration of these long chains between the clay platelets becomes difficult. Moreover the conventional processing methods used do not increase the flowability of the natural rubber sufficiently to allow the delamination of clay platelets from each other. 

There is another, stereoisomeric form of natural rubber, also a polymer of isoprene, called by the wonderful name gutta percha. What do you suppose it is ... 

Natural rubber also undergoes reaction with atmospheric oxygen. This interaction is a major cause of deterioration in physical properties of the rubber on aging and has been extensively investigated. In this book it is possible to give only a brief account of these investigations into an extremely complex process more detailed reviews may be found elsewhere [2,4,6]. 

Natural Rubber Natural rubber, also called India rubber or caoutchouc, is an elastomer that is derived from latex, a milky colloid mainly extracted from rubber trees (Figure 5.1.35). The purified form of natural rubber is polyisoprene, which can also be produced synthetically. Natural rubber is used extensively in many applications and products, as is synthetic rubber. Today, the global annual production of natural rubber is 10 Mio. tonnes, which is about 40% of the total rubber production (natural and synthetic). The three largest producing countries of natural rubber are Thailand, Indonesia, and Malaysia. 

Rubber Natural rubber, also called elastomer, provides the industry worldwide with certain thermoset material properties that to date are not equaled by synthetic elastomers. Examples include tires (with their relative heat buildup resistance), certain type vibrators, etc. However both synthetic TSE and TPE have made major inroads to product markets previously held by natural rubber and also expanded into new markets. The three basic processing types are conventional (vulcanizable) elastomer, reactive type, and thermoplastic elastomer. More synthetic types are used than the natural worldwide. 

With the onset of World War II, immediate work was started to find a commercial substitute for natural rubber because of the restrictions on world movement of goods and likelihood of the loss of rubbergrowing areas in the Far East to the Japanese. Some commercial quantities of GRS, a styrene-butadiene copolymer, became available and modern forms of this make up the rubber type in most popular use, especially in car tyres. After World War II renewed interest in the field of fundamental polymerization technology soon produced a number of new synthetic rubbers, many of which required special additives to assist their processing, whilst others such as ethylene-propylene terpolymer allowed very large volumes of petroleum oil to be used as extenders rather than in limited quantities as plasticizers. Work in the field of natural rubber also enabled large volumes of oil to be used with this polymer. 

The coordinate catalysts enable the s5mthesis on an industrial scale of isoprene rubbers, which in terms of composition, structure and physicochemical properties are similar to natural rubber. Also with these catalysts one can obtain the cw-butadiene rubbers of a regular structure, known for valuable utilization performances. 

Different microstructure, molecular weight, molecular weight distribution and the presence of non-rubbers in natural rubber also account for changed behaviour compared to synthetic polyisoprenes and also between polyisoprenes themselves (see Section 2). 

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