TY  - BOOK
AU  - Solanky S S
AU  - Campistron I
AU  - Reyx D
AU  - Singh R P
TI  - Photo-controlled degradation of natural rubber
PY  - 2000///
PB  - Journal of Rubber Research
KW  - Photo-controlled oxidation
KW  - Rubber degradation
N2  - 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 30 oC under atmospheric air and nitrogen, separately, with a 400 W medium pressure mercury vapour lamp( =>_290nm) 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 13C 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 of hydroxy radical at the methylene-methylene bond. The hydrogen peroxide and/or allylic hydroperoxides acts as photoinitiator by producing hydroxy radicals and/or alkoxy radicals. Moreover, the concomitant addition of 1 O2 (singlet oxygen) via the well known ene reaction producing hydroperoxides, can not be neglected
ER  -