The singlet oxygen (1O2) oxidation of polybutadiene (PB) in presence of polymeric hindered amine light stabilizer (HALS) was studied by determination of viscosity

ESR.

lR.

GFC.. The results show that polymeric HALS can inhibite 1O2 oxidation of PB and the effectiveness is 944 > PDS > 770 > 622. The quenching rate constants of 1O2 by HALS were determined by Monroe's method(19) They are:944(3.2×106)

PDS(8.2×105)

622 and 770 5M-1S-1.The determination of ESR. shows that 944 and PDS can produce stable nitroxy free radi-cal in this experimental condition and 622 does not. This is associated with the steric effect of 622. The determination of GPC also shows that PDS possesses an effect of grafting-crosslin-king to PB in this experimental condition. The mechanizm of grafting-crosslinking has be-en proposed.