Chemical Structure and Occurrence of Natural Polyisoprenes

Abstract

Historical Outline Rubber Production and Consumption Structure of Rubber Synthetic Rubber Outlook and Perspectives Rubber Production Technology Rubber Protein Allergy Purification of Natural Rubber Chemical Structure of Isoprene Units Geometric Isomerism of Isoprene Unit Structure of the Chain‐Ends of Naturally Occurring Polyisoprenes Molecular Weight and Molecular Weight Distribution Occurrence of Polyisoprene in Living Organisms cis ‐Polyisoprene in Higher Plants trans ‐Polyisoprene in Other Higher Plants and Grasses cis‐ Polyisoprene in Mushrooms Natural Rubber from H. brasiliensis Production of Commercial Natural Rubber and Latex Composition of Natural Rubber Structure of both Chain Ends of Natural Rubber Structure of Branch‐Points and Gel Structure of trans‐ Polyisoprene from Higher Plants trans ‐Polyisoprene from Chicle trans ‐Polyisoprene from Gutta Percha and Balata trans ‐Polyisoprene from Eucommia ulmoides Other Natural Polyisoprenes Structure of cis ‐Polyisoprene from Fungi Structure of cis ‐Polyisoprene from Other Higher Plants

Biodegradation of Natural Rubber and Related Compounds: Recent Insights into a Hardly Understood Catabolic Capability of Microorganisms

“…Alternatively, vulcanization is also achieved by employing organic peroxides (32) or radiation (51); such vulcanized materials have lower long-term stability since the polymer chains are cross-linked solely by carbon bonds. Although the first synthetic rubbers were produced at the beginning of the last century, only after 1950, after the development of stereospecific catalysts, could polyisoprene be synthesized in the cis and trans configurations (52). Today it is possible to produce synthetic polyisoprene that has physical properties similar to those of natural rubber with a purity of 98 to 99%.…”

“…Today it is possible to produce synthetic polyisoprene that has physical properties similar to those of natural rubber with a purity of 98 to 99%. However, the stress stability, processability, and other parameters of synthetic polyisoprene are still less satisfying than those of natural rubber (52).…”

“…1). However, polyisoprene of H. brasiliensis contains in addition two trans-isoprene units in the terminal region (52). Although approximately 2,000 plants synthesize poly(cis-1,4-isoprene), only natural rubber of H. brasiliensis (99% of the world market) and guayule rubber of Parthenium argentatum (1% of the world market) are produced commercially (52).…”

“…However, polyisoprene of H. brasiliensis contains in addition two trans-isoprene units in the terminal region (52). Although approximately 2,000 plants synthesize poly(cis-1,4-isoprene), only natural rubber of H. brasiliensis (99% of the world market) and guayule rubber of Parthenium argentatum (1% of the world market) are produced commercially (52). Latex of Hevea plants contains about 30% poly(cis-1,4-isoprene) and is harvested by a "tapping" procedure after the bark of the plants is notched diagonally, which yields 100 to 200 ml latex resin within 3 h. Such "tapping" is usually carried out every 2 to 3 days, yielding up to 2,500 kg of natural rubber per year per ha.…”

Historical and Recent Achievements in the Field of Microbial Degradation of Natural and Synthetic Rubber

“…The products comprised 42.4% NR and 57.6% synthetic rubber. NR is an industrially important polymer and is used for many technical applications such as fabrication of automobile tires, for which most NR is used (53,62). NR is a polymer composed of many C 5 H 8 isoprene units (Fig.…”