Design of molecular structure of star medium vinyl butadiene rubber

摘要

In order to achieve low rolling resistance, high wet grip and favorable overall performance of medium vinyl butadiene rubber (MVBR), the influence of structure factors on them was analyzed from the relationship between molecular structure and its properties. The favorable structure of star-MVBR was designed, which including molecular chain end, arm number(AN), Vinyl content(Bv%), molecular weight for one arm(M_w/arm) and distribution of molecular weight. star-MVBR was synthesized by one step polymerization with new invented multi-functional group organic lithium by our lab as initiator, THF as structure regulator and carbon-hydrogen compoud as solvent. The regulating means of structure factor was analyzed and overall performance was studied. The results showed that the end of star-MVBR molecular chain was coupled by Sn-containing coupling agent, which resulted in low rolling resistance. Bv% and M_w/arm were regulated from 35% to 55%, 6 to 10 ten thousand, with which wet grip was improved. And the favorable molecular structure of star-MVBR could improve its mechanic al and processing properties. S-MVBR, with AN of 3.8, M_w/arm of 8 ten thousand, Bv% of 49.7% and distribution of molecular weight of 1.54, has optimal overall properties. Compared with cis-BR and linear MVBR, star-MVBR has low rolling energy loss, high wet grip, good mechanical and processing properties. It is an ideal rubber for high performance tire tread.