Indexed by:期刊论文

Date of Publication:2007-08-01

Journal:POLYMER INTERNATIONAL

Included Journals:SCIE、EI、Scopus

Volume:56

Issue:8

Page Number:1021-1028

ISSN No.:0959-8103

Key Words:anionic polymerization; 1,2-butadiene; molecular weight distribution; microstructure; styrenebutadiene copolymer

Abstract:1,2-Butadiene is shown to be a chain terminating/transferring agent in butyllithium-initiated diene polymerization. The influence of 1,2-butadiene on the anionic copolymerization of 1,3-butadiene and styrene is investigated using n-butyllithium as initiator and tetrahydrofuran or N,N,N',N'-tetramethylethylenediamine as polar additive. A decrease of copolymerization rate is observed on the addition of 1,2-butadiene. On introducing 1,2-butadiene, the number average molecular weight ((M) over bar (n)) decreases and the molecular weight distribution broadens. The vinyl content of copolymer increases slightly with an increase of 1,2-butadiene. During the copolymerization, 1,2-butadiene in the presence of a high ratio of polar additives to n-butyllithium greatly decreases the copolymerization rate, resulting in a lower value of (M) over bar (n) and a narrower molecular weight distribution than that found for a low ratio of polar additives to n-butyllithium. This evolution can be explained by the basecatalyzed isomerization of 1,2-butadiene to form 1-butylene in the presence of polar additives. With an increasing amount of 1,2-butadiene, the vulcanized rubber exhibits an increased rolling resistance and a reduced wet skid resistance owing to the decrease of coupling cfficiency. These results further indicate the activity of alkynyllithium derivatives produced by the reaction of alkyllithiurn and 1-butyne is less than that of the alkyllithium. (c) 2007 Society of Chemical Industry.