Formation and Reduction of Mal-Odor from Natural Rubber

Abstract

Pollution caused by mal-odor has been an unavoidable problem from all natural rubber industries. This problem has been awared but never been systematically solved in Thailand. The main objective of this research is to characterize the major components that cause mal-odor from natural rubber samples. The different form of natural rubber samples from industries were analyzed: cup lumps rubber, Ribbed Smoke Sheet (RSS) and Standard Thai Rubber(STR) using headspace technique to collect the volatile mal-odor. The major characterization techniques for this study are gas chromatography(GC) and gas chromatography/mass spectrometry(GC/MS). Fifty one compounds in the mal-odor were identified. The volatile mal-odor compounds found in natural rubber were aliphatic compounds, volatile fatty acid (VFA) and aromatic compounds. Themajor components of mal-odor discovered in all sample were ethylamine, pentanone, benzylhydrazine and volatile fatty acids such as acetic acid, propionic acid, isobutylric acid, butyric acid, isovaleric acid and valeric acid. Samples having the strongest mal-odor showed high amounts of these components. Unlike other samples, aromatic compounds were found as another major components of mal-odor in the smoke rubber samples. The odor-reducing substances used in this research were carbon black, chitosan, benzalkonium chloride, sodium dodecyl sulphate (SDS), cyclodextrin and zeolite13x. These substances were mixed with rubber samples (STR20 and Smoke5) in the ratio of 1.5 and 5.0 phr. By two-roll mill. GC analysis, olfactrometry test and mechanical test suggested that efficient odor-reducing substances were chitosan, zeolite13x and carbon black.