Determination of Chemical Components that Cause Mal-Odor from Natural Rubber

Odorous components emitted from different forms of solid natural rubber (NR) were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) associated with head space sampling technique. The most odorous components from most samples were identified as low molecular weight volatile fatty acids (C2-C5). Other volatile organic contents verified based on characteristic ions of mass spectra included carbonyl compounds, low molecular weight compounds containing nitrogen or sulfur and aromatic compounds. The total content and composition of volatile organic compounds were directly correlated to the rubber quality and drying process. Low-grade NR samples, i.e. STR 20 from cup lumps with intense smell, had high quantity of volatile organic contents especially low molecular weight volatile fatty acids. On the other hand, high-quality rubber, i.e. deproteinized NR and STR 5L from which no smell was detected, contained only minute quantities of volatile organic contents. Aromatic components were regarded as other major odorous contents found in ribbed smoked sheet (RSS) samples. The results suggested that the odorous components were the by-products of non-rubber components which had undergone microbial breakdown during storage or thermal degradation during processing.