Abstract - Preparation of Low Molecular Weight Natural Rubbe, by Ozonolysis of High Ammonia Latex


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	Publications of MRB Latest Publications MRB Digest Journal of Rubber Research 3^rd Qtr 2008 Vol 11(3) 2^nd Qtr 2008 Vol 11(2) 1^st Qtr 2008 Vol 11(1) 4^th Qtr 2007 Vol 10(4) 3^rd Qtr 2007 Vol 10(3) 2^nd Qtr 2007 Vol 10(2) 1^st Qtr 2007 Vol 10(1) 1^st Qtr 2006 Vol 9(1) 2^nd Qtr 2006 Vol 9(2) 3^rd Qtr 2006 Vol 9(3) 4^th Qtr 2006 Vol 9(4) Submit paper/article Order Form	Abstract Preparation of Low Molecular Weight Natural Rubbe, by Ozonolysis of High Ammonia Latex Soji Kodama, Katsushi Nishi and Mutsuhisa Furukawa Depolymerisation of natural rubber (NR) by bubbling ozone into high ammonia latex was attempted in order to prepare liquid natural rubber NR was found to depolymerise at a faster rate with increasing ozone generation. Addition of hydrogen peroxide to the latex accelerated the depolymerisation of NR. Regardless of added hydrogen peroxide concentration, when the pH of latex was above 8 at the initial stage of reaction, the rate of depolymerisation was remarkably rapid. However, subsequently, the reaction abruptly slowed when the pH, fell below 8. The decrease in pH was due to the, formation of levulinic acid during reaction. These results suggested that the main reaction of the depolymerisation in latex was not direct oxidation by ozone through the formation of ozonide, but radical oxidation by hydroxyl and hydroperoxvl radicals formed by reaction between ozone and hydroxyl ion under basic conditions. It seemed that the verv slow depolymerisation below pH 8 was due to the, formation of levulinic acid. from a terminal of a polymer chain, by direct oxidation of ozone. The minimum weight-average molecular-weight of the depolymerised NR achieved was about 50 000. back
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