Unusual rheological behaviors of linear PE and PE/kaolin composite

The unusual flow behaviors of linear PE melts are caused by high molecular weight, tight entanglements of molecular chains, and strong adsorption of t he melt at the capillary wall. Especially, the extreme change of interface adsorption is followed by an unusual flow, and at the molecular level, the dynamic variety of entanglement and disentanglement between the adsorption chain near the wall and the nonadsorption chain is the cause of the extrusi on pressure vibration. Ultrahigh molecular weight polyethylene (UHMWPE)/kao lin composites prepared by polymerization filling could be smoothly extrude d through the capillary. Also, with increase of the kaolin content, the app arent viscosity of the composite decreased and the processability was impro ved. Under slip boundary conditions, the real shear rate and shear stress o f the melt near the capillary wall were reduced. The viscosity descent (des orption) and the deformation energy decrease of the melt near the wall were the important preconditions to gain a steady flow in a second glossy zone. (C) 2001 John Wiley & Sons, Inc.