Phase Behavior of Semicrystalline Polyester Resin in Supercritical Fluid Solvents and Solvent Mixtures:Implications for Supercritical Fluid Processing

摘要

Cloud-point data between 40 and 240degC and pressures to 2750 bar are presented for a low molecular weight, semicrystalline polyester resin of 53.4 mol % adipic acid and 46.6 mol % 1,4-cyclohexanedimethanor in supercritical CO_2, dimethyl ether (DME), arid chlorodifluoromethane(CDFM), and in mixtures of CO_2 with DME, CDFM, methanol, ethanol.butanol, octanol, hexafluoroisopropanor, acetone, and cyclo-hexane. Carbon dioxide, by itself, is an extremely weak supercritical fluid (SCF) solvent because this polyester only dissolves at pressures in excess of 2000 bar and at temper-atures over 180degC. However, DME and CDFM are excellent solvents for this polyester, which dissolves at 16 bar and 40degC in CDFM and at 167 bar and 55degC in DME. The melting point of this polyester is reduced from 105 to 40degC in CDFM and to 55degc in DME, which makes the polyester amenable to high intensity mixing for the efficient dispersion of inorganics or crosslinking agents and other hard to deposit materials.