Amorphous poly(ethylene isophthalate) (PET) was synthesized, and was used for preparing an inclusion compound (IC) with gamma-cyclodextrin (gamma-CD). Coalesced polymer was produced by washing the PEI-gamma-CD-IC with hot water. Wide angle X-ray diffraction, Fourier transform infrared, and differential scanning calorimetry analyses were employed to verify formation of PEI-gamma-CD-IC and to compare the as-synthesized and coalesced PEI samples. These observations suggested that the conformations and morphology/ chain-packing of PEI were changed via coalescence from its gamma-CD inclusion compound. The glass-transition temperature of the amorphous coalesced PEI is 15-20 degrees C higher than the T-g, observed for the as-synthesized sample, even when observed in the second heat after cooling from well above T-g, at 260 degrees C. The amorphous as-synthesized PEI retains its randomly-coiling structure, while coalesced PEI has at least partially retained, the hightly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains manifested by a higher T-g. (c) 2006 Wiley Periodicals, Inc.