Copolyesters, were synthesized through the condensation of 0.0025 mol of 1,1'-bis(3-methyl-4-hydroxy-phenyl)cyclohexane, 0.0025 mol of ethylene glycol/propylene glycol/1,4-butanediol/ 1,6-hexane diol, and 0.005 mol of terephthaloyl chloride with water/chloroform (4:1 v/v) as an interphase, 0.0125 mol of sodium hydroxide as an acid acceptor, and 50 mg of cetyl trimethyl ammonium bromide as an emulsifier. The reaction time and temperature were 2 h and 0 degrees C, respectively. The yields of the copolyesters were 81-96%. The structures of the copolyesters were supported by Fourier transform infrared and H-1-NMR spectral data and were characterized with the Solution viscosity and density by a floatation method (1.1011-1.2697 g/cm(3)) Both the intrinsic viscosity and density of the copolyesters decreased with the nature and alkyl chain length of the diol. The copolyesters possessed fairly good hydrolytic stability against water and 10% Solutions of acids, alkalis, and salts at room temperature. The copolyesters possessed inoderate-to-good tensile strength (11-37.5 MPa), good-to-excel lent electric strength (19-45.6 kV/mm), excellent volume resistivity (3.8 X 10(15) to 2.56 X 10(17) Omega cm), and high glass-transition temperatures (148-195 degrees C) and were thermally stable up to about 408-427 degrees C in a nitrogen atmosphere; they followed single-step degradation kinetics involving 38-58% weight losses and 34-59% residues. The copolyesters followed 2.6-2.9-order degradation kinetics. (c) 2007 Wiley Periodicals,