Characterization of chemical structure and determination of composition of Vietnam commercial natural rubbers (CNR) were carried out to investigate the relationship between structure and properties of natural rubber. Five different grades of CNRs used are SVR10, SVR5, SVR3L, SVRCV50 and SVRCV60. The CNRs films were prepared by solution casting technique following by acetone extraction. The structure of the samples was investigated by 1H-NMR spectroscopy and FT-IR spectroscopy. It is found that epoxidation ocurred in SVR5 and SVRCV50 and isomerization ocurred in SVR5, SVR10, SVRCV50 and SVRCV60, but not in SVR3L. The nitrogen content, fatty acid ester content and gel content of the rubbers are similar, except SVR10 with lowest nitrogen content and SVRCV50 with the lowest gel content. The mechanical strength of SVRCV50 is the poorest and SVR10 is the strongest. The mechanical properties depends on the damage of the rubbers and gel content.
Keyword
Vietnam commercial natural rubber, 1H-NMR, epoxidation, gel content, non rubber components
