A novel technique for micronizing polyethylene terephthalate (PET) resin (similar to 3 mm) with saturated liquid tetrahydrofuran (THF) has been developed. PET pellets were introduced to a high-pressure vessel filled halfway with THF at loadings up to similar to 7 wt % PET. When the vessel was closed and heated, the PET pellets exhibited significant melting point depression at 190 degrees C in saturated liquid THF at 17.1 bar. Although other organic solvents were also able to depress the melting point of PET, only THF was able to facilitate the formation of an emulsion of PET-rich liquid droplets in the saturated liquid solvent when the mixture was agitated. In an attempt to generate the smallest possible PET droplets, a high-speed (5000 rpm), close-clearance, radial flow impeller was used to shear and disperse the droplets at similar to 200 degrees C and 20.1 bar. Emulsion was rapidly cooled while mixing. The PET droplets froze at similar to 190 degrees C, and the vessel was then cooled to ambient temperature. The excess liquid THF was decanted, and the PET particles were dried in a vacuum oven to remove residual THF. The PET particle sizes ranged between 2 and 70 mu m, with number, area, and volume average diameters of 6, 20, and 30 mu m, respectively. A comparison between the PET resin and PET powder properties indicated that the micronization reduced the Mw from 32,700 to 22,800. DSC results suggest that the rapid quench leads to a morphology different from equilibrium, with small somewhat imperfect crystallites, a lower overall degree of crystallinity, and a suppressed ?Cp at the glass transition. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012