2012|13 Annual Report Fraunhofer IGB

8 8 Rubber is a polymer used in a wide variety of everyday ap- plications, including balls, household gloves, gaskets and car tires. This is reﬂected in the high global demand for rubber. In 2012, according to estimations 27.6 million metric tons [1] were used, two thirds of which were required for the produc- tion of car tires alone. Natural rubber, which consists of iso- prene units, can only be substituted to a limited extent by syn- thetic rubber, polyisoprene, due to differing properties of the natural product if compared to chemically produced polymers. The natural polymer is therefore present in over 40,000 prod- ucts including 400 medical products [2]. Natural rubber from the Russian dandelion (Taraxacum koksaghyz) To date, rubber has been identiﬁed in approximately 2500 plants, but only one is used for commercial production pur- poses. This is Hevea brasiliensis, the rubber tree [3]. However, stocks of this tree are under threat from South American leaf blight. In addition, the milk-like sap of the rubber tree, the la- tex, contains not only rubber but also proteins which cause allergies in some people. As an alternative to Hevea brasilien- sis, as early as at the beginning of the 20th century a possibil- ity emerged to isolate rubber from a natural resource in the northern hemisphere: This alternative is the Russian dande- lion (Taraxacum koksaghyz). Taraxacum koksaghyz is a robust plant that can also be grown on marginal soils. The rubber content in the latex of the Russian dandelion is, on average, close to 30 percent [3]. The content of latex in the root is about 4 percent of the dryweight according to our analyses. Extracting and processing the natural rubber The rubber can be extracted directly as a chewing-gum-like substance from dried or fresh dandelion roots and separated from the biomass. To do this, a sequence of process engi- neering steps are used. This includes processes such as steam treatment, grinding, ﬂoating and sieving [4]. The Fraunhofer IGB is currently reﬁning the methods which have been known for 60 years already and looking for cost-effective alternatives for industrial implementation. On the other hand, latex can, either through exposure to acid or through evaporation of the water and the vulcanization process, agglomerate and subsequently coagulate and thus be obtained from the liquid latex. Approximately 90 percent of the latex is converted into rubber used e.g. for tires whilst the remaining 10 percent is processed into commercial latex products such as condoms or gloves which are more elastic [5]. In order to prevent the premature coagulation of the rub- ber molecules and retain the plasticity, the latex milk of Hevea brasiliensis is mixed with stabilizing agents and antioxidants immediately after extraction. The Fraunhofer IGB is compar- ing various extraction methods and a variety of additives that enables the prevention of agglomeration, which is the stage before coagulation also in Russian dandelion latex extracts. Using new combinations of additives, it is now possible to stabilize the latex solutions for at least 3 months. Currently, latices with a rubber content of up to 15 percent can be pro- duced. The next step is the scale-up of the puriﬁcation steps performed from a laboratory to an industrial scale. CHEMISTRY EXTRACTING RUBBER, LATEX AND INULIN FROM DANDELION ROOTS Dipl.-Chem. Thomas Hahn, Dipl.-Biol. (t. o.) Dipl.-Ing. (FH) Susanne Zibek 1 2

2012|13 Annual Report Fraunhofer IGB

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