THE RHEOLOGICAL BEHAVIOR OF POLYETHERETHERKETONE (PEEK) POLYETHERIMIDE (PEI) BLENDS

A study on the rheological behavior at high shear rates of PEEK/PEI bl ends has been performed by means of a capillary viscometer at two temp eratures (350 and 370 degrees C). PEEK (polyetheretherketone) is a tou gh semicrystalline polymer with properties that make it very attractiv e for use as a high-quality engineering thermoplastic. It has been mel t-blended with amorphous PEI (polyetherimide), another high-performanc e polymer. From previous studies it was known that PEEK/PEI blends are miscible over the whole composition range. A hoped-for enhancement in processability has been achieved only with a medium content of PEI an d at a higher temperature. Finally, a phenomenological equation (Cross equation) has been used to correlate the experimental viscosity value s and to predict the rheological behavior of the PEEK/PEI blends even at very low shear rates. The model has been found to fit all the exper imental data well at both 350 and 370 degrees C.