of the absorption band around 837 cmÿ1 and
the appearance of an absorption band around
1086 cmÿ1, presumably due to carbon=oxygen functionalities.
This suggests that oxidation of natural
rubber is occurring primarily at the vinyl functionality.
The blend became distinctly yellow in
appearance during heating. The infrared spectrum
of the 1:1 wt% blend exhibited a strong absorption
band around 1720 cmÿ1, assigned to C O stretch.
The absorption band originally at around 837 cmÿ1
decreased considerably in intensity. The relative
absorbance of the absorption band at 1450 cmÿ1
also decreased. There were absorption bands around
1240 cmÿ1 and 1080 cmÿ1, which were presumably
associated with carbon=oxygen functionalities, possibly