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Ozonation of unstretched natural rubber film from Hevea brasiliensis studied by ozone consumption and 13 C NMR
Author(s) -
Rodrigues FHA,
Santos EF,
Feitosa JPA,
Ricardo NMPS,
Heatley F
Publication year - 2004
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1265
Subject(s) - ozone , natural rubber , ozonolysis , hevea brasiliensis , stoichiometry , chemistry , materials science , chemical engineering , organic chemistry , polymer chemistry , engineering
Unstretched films of natural rubber (NR) from Hevea brasiliensis were exposed to ozone flow of 15 ml min −1 from 4 to 300 min. The efficiency of reaction was determined by ozone consumption of NR films. Plots of reacted ozone mass versus film thickness show that the ozone penetration and the ozone reaction progressed into deeper layers (170 µm) than described in the literature (∼0.5 µm). The previous proposed model based on viscometry measurements was corroborated by ozone consumption results. The effect of thickness on the O 3 /NR stoichiometric ratio indicated that the diffusion process that controls the ozonation in unstretched film does not consist of the boundary progression behind which all reactive sites have been saturated. Ozonation in unstretched rubber film, while being less efficient than ozonolysis in solution, does have a reaction efficiency of the same order of magnitude. NMR spectroscopy was used to characterise the products formed by ozonation. Copyright © 2004 Society of Chemical Industry