Rheological measurements for PP melts with different M & MWD have been made in a capillary rheometer with length/diameter ratio 0

6.4

40

100 as well as in cone/ plate and falling sphere viscometers. Melt transition in entrance converging flow was observed under about 208℃ which causes the increase of flow drag. The successive capillary could eliminate this structuring effect. This phenomenon was not observed in pure shear flow which should be distinguished from the stress induced crystallization of melt.A mechanism was suggested b assuming the existence of week mesomorphic state under 208℃ which can be strengthened in converging flow.