Citation
Singh R. P., . and Solanky S. S., . and Reyx D., . and Campistron I., . Photo-controlled degradation of natural rubber. pp. 76-94. ISSN 1511-1768
Abstract
The chain cleavage mechanisms during hydrogen peroxide catalysed photo-oxidative degradation of high molecular weight natural rubber which was described as producing liquid natural rubber is elucidated. NR is photolysed in toluene solution (2.5 wt. ) in a photoreactor at 30C under atmospheric air and nitrogen separately with a 400 W medium pressure mercury vapour lamp (lambda more and equal 290 nm) with constant stirring in the presence of hydrogen peroxide and/or titanium dioxide. The decrease in viscosity-average molecular weight (Mv) was determined by viscosity measurements. The photoproducts were characterised by FT-IR 1H and I3C NMR spectroscopies. Burfields and the present results gave indication for chain cleavages resulting from the classical free-radical oxidation process rather than a direct reaction ofhydroxy radical at the methylene-methyiene bond. The hydrogen peroxide and/or allylic hydroperoxides act as photoinitiator by producing hydroxy radicals and/or alkoxy radicals. Moreover the concomitant addition of 1O2 (singlet oxygen) via the well known ene reaction producing hydroperoxides can not be neglected.
Download File
Full text available from:
Official URL: http://vitaldoc.lgm.gov.my:8060/vital/access/servi...
|
Abstract
The chain cleavage mechanisms during hydrogen peroxide catalysed photo-oxidative degradation of high molecular weight natural rubber which was described as producing liquid natural rubber is elucidated. NR is photolysed in toluene solution (2.5 wt. ) in a photoreactor at 30C under atmospheric air and nitrogen separately with a 400 W medium pressure mercury vapour lamp (lambda more and equal 290 nm) with constant stirring in the presence of hydrogen peroxide and/or titanium dioxide. The decrease in viscosity-average molecular weight (Mv) was determined by viscosity measurements. The photoproducts were characterised by FT-IR 1H and I3C NMR spectroscopies. Burfields and the present results gave indication for chain cleavages resulting from the classical free-radical oxidation process rather than a direct reaction ofhydroxy radical at the methylene-methyiene bond. The hydrogen peroxide and/or allylic hydroperoxides act as photoinitiator by producing hydroxy radicals and/or alkoxy radicals. Moreover the concomitant addition of 1O2 (singlet oxygen) via the well known ene reaction producing hydroperoxides can not be neglected.
Additional Metadata
| Item Type: | Article |
|---|---|
| AGROVOC Term: | Natural rubber |
| AGROVOC Term: | Hydrogen peroxide |
| AGROVOC Term: | Degradation |
| AGROVOC Term: | Molecular weight |
| AGROVOC Term: | Photolysis |
| AGROVOC Term: | Toluene |
| AGROVOC Term: | Mercury |
| AGROVOC Term: | Stirring |
| AGROVOC Term: | Ketones |
| AGROVOC Term: | Irradiation |
| Depositing User: | Ms. Suzila Mohamad Kasim |
| Last Modified: | 24 Apr 2025 06:28 |
| URI: | http://webagris.upm.edu.my/id/eprint/22924 |
Actions (login required)
 |
View Item |
