The selective catalytic hydrogenation of living styrene-butadiene copolymer (SBS) prepared in the presence of metallocene catalyst modified by methyl benzoate was studied.The effects of factors

such as number-average molecular weight (Mn) of SBS

on the hydrogenation degree of the copolymers under different experimental conditions were discussed.The results show that when the ratio of Ti to 100 g dry copolymer is in the range of 0.15～0.3 mmol

adding methyl benzoate in a special mode can significantly improve the activity of titanocene catalyst.The hydrogenation degree of both SBS basic copolymers with Mn of 6.5104 and 5.5104 respectively are ＜97.0% after reaction for 180 min in the case of using metallocene catalyst not modified by methyl benzoate.On the other hand

the hydrogenation degree of the same SBS samples is 98.0% after reaction for 60～120 min under the condition of using the modified metallocene catalyst.In contrast with the similar researches reported before

our experiments could shorten the hydrogenation time by 60～120 min.When the ratio of Ti to 100g dry copolymer falls in the range of 015～0.3 mmol

the hydrogenation degree of the SBS basic copolymer is affected by magnitude of the Mn.For 30 min after the reaction

the hydrogenation degree of SBS copolymer with Mn of 5.5104 is 97.0% whereas that of the copolymer with Mn of 6.5104 is ＜90.0%.The disparity in hydrogenation degree between the two SBS copolymers is gradually diminished as the hydrogenation process proceeds and becomes unobvious after reaction for 180 min.In such a case the hydrogenation degree of both SBS basic copolymers are 98%.The effect of every influential factor on the hydrogenation degree of the SBS copolymers is elucidated in terms of the hydrogenation mechanism.