The blending process of poly(ether imide)/polycarbonate (PEI/PC) was studied by visualization of blending in an internal mixer at 340degreesC. Distinct pellet deforming, softening, aggregation, stretching, bending, sheeting, and dispersing were seen during the blending process. By ramping the temperature of the barrel of the internal mixer, the process of pellet softening and deforming, and the phase-inversion phenomenon were studied by examining the visualization results and the torque readings. It was found that a peak in torque occurred at the phase-inversion point. It was also found that the blends are semitransparent at higher PEI composition (>80 wt %). SEM and TEM micrographs and DSC data verified the visualization result that PEI/PC blends are partially miscible at higher PEI compositions. The number-average particle size was determined for the PEI/PC blends and it was found that the experimental results in the dilute solution limit for both PC drops and PEI drops did not match with the particle size predicted by Taylor's theory. The particle sizes at 15 wt % concentration were of the same order of magnitude as those calculated using Wu's correlation. (C) 2004 Wiley Periodicals, Inc.