Preparation and characterization of poly(ethylene-1,4-cyclohexanedimethylene arylate)

Copolyesters containing aromatic segment (naphthalene & benzene) and aliphatic segment (cyclohexanedimethylene & ethylene) structure were synthesized from bis(hydroxyethyl)arylate (BHEA) and bis(hydroxymethyl-cyclohexane)arylate (BHCA) in various molar ratio. Copolyesters having intrinsic viscosities of 0.53–0.65 dl/g were obtained by the melt polycondensation in the presence of metallic catalysts. The optimum condition for PECA (polyethylene-1,4-cyclohexanedimethylene arylate) copolyester preparation is the transesterification under nitrogen atmosphere for 4 h at a temperature of 245±5°C, followed by polymerization under 2 mm Hg for 50 min at a temperature of 290–320°C. Most copolyesters have better thermal stability than poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET), and the effect of cyclohexanedimethylene structure on the thermal and crystalline properties of the resulted copolyesters were investigated using the differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Glass transition temperatures (Tg) of copolyesters from bis(hydroxyethyl)naphthalate / bis(hydroxymethylcyclohexane)napththalate (BHEN/BHCN) were in the range of 115.2–138.4°C, and 10% weight loss in nitrogen were all above 453°C. Another series of copolyesters from bis(hydroxyethyl)terephthalate / bis(hydroxymethylcyclohexane)terephthalate (BHET/BHCT) system have Tg in the range of 69.2–96.6°C, and 10% weight loss in nitrogen of over 426°C. The solubility, crystallinity and moisture absorption of copolyesters were also investigated.