Solid-state 13C-NMR studies of changes in crosslinked carbon structure of natural rubber during heating under air and nitrogen environments

✍ Scribed by Dallas D. Parker; J. L. Koenig

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 298 KB
• Volume: 70
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19981114)70:7<1371::aid-app12>3.0.co;2-3

✦ Synopsis

The chemical changes that occur in thermal degradation of sulfur-cured natural rubber were investigated using 13 C-NMR analysis. The crosslinked carbons formed during the vulcanization process appear in the NMR spectra as peaks representing the various structures formed. Samples of vulcanized rubber were heat-aged at 100 and 150°C under both air (oxidative) and nitrogen (inert) environments to assess both temperature and oxidative effects. Changes were observed by measuring peak areas under the crosslinked carbon peaks. A-and B-type cis monolinkages were found to decompose much faster by oxidative factors at both 100 and 150°C than under nitrogen at either temperature. The polylinkages, however, showed the opposite result of thermal degradation predominating over oxidative factors. Cis-trans isomerization of the main chain carbons was observed at the higher temperature while absent at 100°C.