EFFECTS OF THE LOW-SURFACE-ENERGY COMPONENT ON THE VISCOSITY OF POLY(ETHER ETHER KETONE) AND POLYTETRAFLUOROETHYLENE BLENDS

The effects of a low-surface-energy component, polytetrafluoroethylene (PTFE), on the apparent viscosity of poly(ether ether ketone) (PEEK) were studied. Blends of PEEK and PTFE were prepared by using a twin-counter-rotating-screw extruder (ZSE). One percent and five percent by weight of PTFE were used. The apparent viscosity of the blends as a function of apparent shear rate was determined by a capillary rheometer. The observed reduction in the apparent viscosity is attributed to the migration and accumulation of the low-surface-energy component (PTFE) at the interface between the die wall and the melt. The enrichment of PTFE on the surface of the extrudates was confirmed by x-ray photoelectron spectroscopy. Surface enrichment of PTFE and viscosity reduction are enhanced with an increase in shear rate and PTFE concentration in the blend.