Rubber yielding plants

P.J. George, and A.O.N.Panikkar, Rubber yielding plants, in Natural Rubber Agro-Management and Crop Processing, Rubber Research Institute of India, Kottayam, Kerala,... 

The Russian dandelion, which may contain up to 10% of good quality rubber. The plants are harvested and the rubber obtained in the manner of sugar from sugar beet. It is claimed that the yield per acre approaches that of plantation rubber. 

The HbHnl is obtained from the leaves of the rubber tree plant and a crude extract is easily prepared by homogenisation of the frozen leaves, followed by centrifugation [38-40]. A 5-step purification procedure of this crude extract (with over a 100-fold purification factor) to yield a homogenous HbHnl has... 

A genus of trees yielding a good type of natural rubber, of little commercial importance nowadays. The Ficus elastica is the well-known ornamental rubber plant. 

A term applied to clones of Hevea trees which give a much higher yield of latex than ordinary rubber trees. The average yield in the 1950s was under 500 kg of rubber per hectare per annum. It is now more common to achieve a two- to threefold increase on these figures from modem planting material. 

The amount of dry natural rubber produced per acre per annum. The yield from the original trees established in Malaysia was only about 400 kg per hectare per annum, but the best planting material available nowadays can product about 2000-2500 kg per hectare. See Bud Grafting, High Yielding, Ladder Tapping, Yield Stimulation. 

The application of plant hormones to the bark of rubber trees, or of copper sulphate placed in holes bored in the trunk, can produce a consistent increase in yield without any damage to the tree or any deleterious effect on either the latex or the rubber produced from it. 

With reaction conditions of 200-225°F, 150—225 psi, and a palladium chloride-cupric chloride catalyst, MEK yields are 80-90%. The operating costs of the Wacker process for MEK (and acetone and several other petrochemicals as well) are relatively low. But the plant Is made of more expensive materials. Because of the corrosive nature of the catalyst solution, critical vessels, and the piping are titanium-based.(chats expensive ), and the reactor is rubber-lined, acid-resistant brick. ... 

Solution polymerization is bulk polymerization in which excess monomer serves as the solvent. Solution polymerization, used at approximately 13 plants, is a newer, less conventional process than emulsion polymerization for the commercial production of crumb mbber. Polymerization generally proceeds by ionic mechanisms. This system permits the use of stereospecific catalysts of the Ziegler-Natta or alkyl lithium types which make it possible to polymerize monomers into a cis structure characteristic that is very similar to that of natural rubber. This cis structure yields a rubbery product, as opposed to a trans stmcture which produces a rigid product similar to plastics. 

Several biomass species have been found to contain oils and/or hydrocarbons (Table 13). It is apparent that oil or hydrocarbon formation is not limited to any one family or type of biomass. Interestingly, some species in the Euphorbiaceae family, which includes Hevea bra iliensis, form hydrocarbons having molecular weights considerably less than that of natural rubber at yields as high as 10 wt% of the plant. This corresponds to hydrocarbon yields of about 3.97 m3/hm2-yr(25bbl/hm2-yr). 

PVCA is a copolymer of vinyl chloride and vinyl acetate. It is a colorless thermoplastic solid with good resistance to water as well as concentrated acids and alkalis. It is obtainable in the form of granules, solutions, and emulsions. Compounded with plasticizers, it yields a flexible material superior to rubber in aging properties. It is widely used for cable and wire coverings, in chemical plants, and in protective garments. 

IP-PP and DMA-PP can yield volatile C3 hemiterpenes. At the other extreme, extensive polymerization of the C3-pyrophosphates (with release of pyrophosphate, PP ) yields the formation of the plant latex polymers such as eis-polyisoprenes (rubber) and trans-polyisoprenes (gutta-percha). In between these extremes, a variety of monoterpenes, sesquiterpenes, triterpenes and C3() carotenes derive from these C3-pyrophosphate precursors. 

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