Natural rubber guayule

Rubber obtained from botanical sources. The bulk of natural rubber is obtained from the Hevea Brasiliensis free with small amounts from other vines, shrubs and plants mainly the Guayule shrub and the Kok-Saghyz plant. See Isoprene. 

The chlorination of low molecular weight natural rubber from Guayule (Parthenium Argentatum Grey) has been accomplished. The structure of the chlorinated product is consistent with that of chlorinated Hevea rubber. The use of Azo-bis-isobutyronitrile was as a catalyst resulted in increased chlorine content with a concomitant reduction in molecular weight, thereby allowing the preparation of lower viscosity grades of chlorinated rubber. 

Figure 1 HNMR of Purified Guayule Natural Rubber...

Guayule An Alternative Source of Natural Rubber, National Academy of Sciences, Washington, D.C., 1977. 

National Academy of Sciences (1977). Guayule An Alternative Source of Natural Rubber. Washington, D.C. Jojoba Feasibility for Cultivation on Indian Reservations in the Sonoran Desert Region. Washington, D.C. 

Another problem is that some persons are allergic to the proteins often found in natural rubber. This can be avoided by the use of a polyurethane condom. Unfortunately, as now made, these are more likely to tear (7-9% of the time) than the rubber latex condoms (2% of the time).65 It has been suggested that they be made of guayule rubber latex, which is free of the allergens.66 Thermoplastic elastomers, such as polystyrene-6-(ethylene-co-butene)-Apolystyr ene have been used to make gloves that are more resistant to ozone than those made of natural rubber.67 These should resist aging better than those made of natural rubber. It should be possible to mold a condom without holes from a thermoplastic rubber. 

Another unusual plant of the American Southwest and Mexico is the bushlike guayule, which produces a form of natural rubber or latex, as do many other plants, even the dandelion, but not in sufficient quantity. The guayule, however, was employed during WWII when the Malaysian sources of natural rubber were cut off. 

In the original scenario, potential rubber crops were considered. Since then, it was decided to develop guayule (Parthenium argentatum) as a domestic source for natural rubber (1. The U.S. rubber market can potentially be supplied by guayule grown in the southwest. Thus, barring discovery of an... 

Polyisoprene occurs in other plants, some of which have been of commercial significance, such as the Russian dandelion and the Mexican guayule shrub. The well-known properties of natural rubber are dbplayed only at temperatures above the glass transition temperature, which is -7(PQ below that temperature it is a brittle glass. Every amorphous pofymer, whether synthetic or natural, providing it is cross-linked, displays comparable properties above its glass transition temperature. These properties are, stated briefly ... 

Chromenes, Benzofurans, Benzopyrans, and Precocenes Polyterpenes Biosynthesis Biological Activity Natural Rubber Hevea brasiliensis Guayule Gutta Percha Chicle... 

Natural rubber is a secondary product, compartmentalized in cytosolic rubber particles, which is not recatabolized during the life of the plant. Rubber particles are often made in laticifers, as in Hevea (5,8), but guayule produces them in generalized bark parenchyma cells (31,32). The rubber particles probably originate... 

J. Bonner, in J. W. Whitworth and E. E. Whitehead, eds., Guayule Natural Rubber, GAMCyUSDA-CSRS, Tucson, Ariz., 1991, pp. 1-16. 

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