The relationships of extrudate distortion and the non -linear viscoelasticity for HDPE

POE

EPDM etc were studied by capillary rheometer. It is indicated that the melt slip at wall and the extrusion pressure oscillation were easy occurred in linear macromolecule melts and difficulter occurred in polymer melts having biger side-group or broader molecule weight distribution

or having a lot of short side-chain. More the chain entanglement

andmore the shear stress between melts and the wall of capillary

the melt slip at wall and the pressure oscillation became stronger. The melts fracture behaviors were influenced more by the extensional viscosity

but less by the steady shear viscosity of melt.