LAUSR

Abstract In this paper, the molecular structures of five kinds of original natural rubber (NR) samples produced by different coagulation methods and from different regions(within six months) were studied using a pyrolysis (at 550 °C) gas chromatography/mass spectrometry (py-GC/MS) technique. The result showed that the similar molecular structures of the major degradation products, monomers (2-methyl-1,3-butadiene and 1,3-pentadiene) along with dimers of a large number of 1-methyl-4-(1-methylethenyl)cyclohexenes (limonenes) and small amounts of tran limonenes, were all found in three original NR samples, SMR20 and STR20 made all by natural coagulation, and MC-SCR5 coagulated rapidly by microorganisms. Also, the relative productivity (57.48%-59.27%) of the monomers are similar. But the some differences of the molecular structures, the monomers which included 1,4-pentadiene, 3-methyl-1,2-butadiene and 2-pentyne along with more tran limonenes dimers were exhibited in two original NR samples, GSR-RSS3 coagulated by new technology and HN-SCR5 by acetic acid, their relative productivities (61.22% and 65%) have also more differences, as compared with that of the bio-coagulated natural rubbers. Conbine our previous and current works, a conclusion can be obtained that the rubber-productions of origin is not the main factor affecting the molecular structures of natural rubber, but the coagulation processing.