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.