| 摘要 |
<p>An elastomeric copolymer of an aromatic vinyl cpd.(I) and a conjugated diene has a differential content of (I) along the polymer. The content of (I) increases sharply in at least one of the end portions towards that end. At least 30% of the diene is linked by 1,2-addition. Pref. (I) is styrene. The diene is pref. butadiene or isoprene. The copolymer is linear and contains at least 10 wt.% styrene. 30-60% of the diene is linked by 1,2-addition. The styrene content increases by 25% over the last 5% of the copolymer chain. The copolymer is produced by soln. polymerisation using an initiator. An excess of styrene is introduced at the start or finish of the polymerisation. The copolymer is used in the tread portion of tyres and gives improved rolling resistance and grip on wet surfaces.</p> |
