SYNTHESIS AND PROPERTIES OF POLY(ETHYLENE-1,4-CYCLOHEXANEDIMETHYLENE NAPHTHALATE)

Copolyesters were synthesized from bis(hydroxyethyl) phthalate/bis(hyd roxymethylcyclohexane)naphthalate (BHEN/BHCN) with various composition s. Copolyesters having intrinsic viscosities of 0.58-0.65 dL g were ob tained by melt polycondensation in the presence of metallic catalysts. The optimum condition for polyethylene-1,4-cyclohexanedimethylene nap hthalate (PECN) copolyester manufacturing is the transesterification u nder a nitrogen atmosphere for 4 h at a temperature of 245 +/- 5 degre es C followed by polymerization under 2 mmHg for 50 min at a temperatu re of 290-320 degrees C. Most copolyesters have better thermal stabili ty than has poly(ethylene naphthalate) (PEN) and the effect of the cyc lohexane-dimethylene structure on the thermal and crystalline properti es of the resulting copolyesters was investigated using differential s canning calorimetry (DSC) and thermal gravimetric analysis (TGA). Glas s transition temperatures of the copolyesters were in the range of 115 .2-138.4 degrees C, and 10% weight losses in nitrogen were all above 4 53 degrees C. The solubility, crystallinity, and moisture absorption o f the copolyesters were also investigated. (C) 1998 John Wiley & Sons, Inc.