STUDY ON SYNTHESIS OF HIGH VINYL POLYBUTADIENE WITH TETRAVALENT MOLYBDENUM CATALYST SYSTEM

In this paper the catalytic behaviour of tetravalent molybdenum catalyst system in polymeriza-tion of butadiene is dealt with. The effects of the variety of apions combined with molybdenumatom, the pattern of the substituent R in (i-Bu)_2AlOR and the polymerization conditions on thebutadiene conversion, the molecular weight and its distribution and the microstructure of the polymeralso are studied. It has been found that the catalyst system is significantly active when anions com-bined with the molybdenum atom are acetoxy (CH_3COO-),or ethoxy (C_2H_5O-). Obviously, thevariety of substituent R in (i-Bu)_2 AlOR has a great influence on the catalytic activity. The catalystsystem is inactive if the R group is--COR' (R'is alkyl or aromatic group) or alkyl, whereas the activityof the catalyst system increases if the R group is phenyl or tolyl. With the rise of polymerizationtemperature the polymer molecular weight decreases, the distribution index of molecular weight in-creases and the content of 1,2-unit in polybutadiene reduces.

STUDY ON SYNTHESIS OF HIGH VINYL POLYBUTADIENE WITH TETRAVALENT MOLYBDENUM CATALYST SYSTEM

 In this paper the catalytic behaviour of tetravalent molybdenum catalyst system in polymeriza-tion of butadiene is dealt with. The effects of the variety of apions combined with molybdenumatom, the pattern of the substituent R in (i-Bu)₂AlOR and the polymerization conditions on thebutadiene conversion, the molecular weight and its distribution and the microstructure of the polymeralso are studied. It has been found that the catalyst system is significantly active when anions com-bined with the molybdenum atom are acetoxy(CH₃COO^-) or ethoxy (C₂H₅O^-).Obviously,the variety of substituent R in (i-Bu)₂ AlOR has a great influence on the catalytic activity.The catalyst system is inactive if the R group is-COR'(R'is alkyl or aromatic group) or alkyl,whereas the activity of the catalyst system increases if the R group is phenyl or tolyl.With the rise of polymerization temperature the polymer molecular weight decreases,the distribution index of molecular weight increases and the content of 1,2-unit in polybutadiene reduces.