Epoxide groups in natural rubber. II. C-NMR study of undegraded natural rubber

Eng, A.H.; Kodoma, S.; Tangpakdee, J.; Kawahara, S.; Tanaka, Y.

Epoxide groups in natural rubber. II. C-NMR study of undegraded natural rubber

1998

Eng, A.H. (Rubber Research Institute of Malaysia, P.O.Box 10150, 50908 Kuala Lumpur (Malaysia)) | Kodoma, S. | Tangpakdee, J. | Kawahara, S. | Tanaka, Y.

The level of epoxide groups on the natural rubber main-chain molecule is examined by 13C-NMR spectroscopy. The results show that while all the rubber samples contain trans isoprene units, purified rubbers from fresh latices contain no detectable amount of epoxide groups. This is also found to be the case for fractionated rubbers of different molecular weights, rubber samples of different clonal origin as well as rubbers isolated from different zones of centrifuged fresh latex. Nevertheless, of the six commercial solid rubber samples examined, SMR L and SMR 10 were found to contain trace amount of cis epoxide, the levels of which are similar to that of trans isoperene units. It is concluded that natural rubber has no detectable amount of epoxide groups on the main-chain molecule.

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