The flow curves of cis 1

4-polybutadiene prepared by four different catalytic systems have been measured by a capillary rheometer.The critical temperature at which the flow curves change from continuousness to discontinusness increased as the cis content increased. It was also found that the long chain branching plays an important role

the better the linearity the higher the critical temperature. The different shapes of extrudate were well explained in the light of the picture that the flow instability can occurs independently at the die-entrance

die outlet and die wall

but the slippage ltself gives no contribution to the irregu-alrity of the extrudate.