In this work, a series of poly(1,4-cyclohexylenedimethylene terephthalate-co-1,4-cyclohexylene dimethylene 2,6-naphthalenedicarboxylate) (PCTN) copolymers with different compositions of two diacids: terephthalic acid (TPA) and 2,6-naphthalenedicarboxylic acid (NDA), and stoichiometry matched 1,4-cyclohexanedimethanol (CHDM) were synthesized directly by a melt polymerization technique. Thermal properties of synthesized copolymers were measured by a differential scanning calorimetry (DSC). The incorporation of either NDA or CHDM improved the glass transition temperature (T_g) of PCTN compared to poly(ethylene terephthalate) (PET). Thermal degradation behaviors were analyzed using a thermogravimetric analysis (TGA). Chemical structures of the obtained copolyesters were investigated by a nuclear magnetic resonance spectroscopy (¹H NMR). Our results showed that the thermal and optical properties (determined by UV-Vis spectrophotometer) of the PCTN copolyesters were directly dependent on the ratio of TPA and NDA. It was also found that PCTN films have superior optical, thermal, and barrier (reduced water absorption) properties than PET and poly(ethylene naphthalate) (PEN) films.

Terephthalic acid(TPA), 2,6-naphthalenedicarboxylic acid(NDA), 1,4-cyclohexanedimethanol(CHDM)을 사용하여 poly(1,4-cyclohexylenedimethylene terephthalate-co-1,4-cyclohexylene dimethylene 2,6-naphthalenedicarboxylate) (PCTN)를 용융중합하였다. DSC를 통해 열특성을 분석하였고, NDA와 CHDM이 첨가된 PCTN 공중합체의 유리전이온도는 poly(ethylene terephthlatae)(PET) 대비 크게 향상됨을 확인하였다. 열분해 거동은 TGA를 사용하여 확인하고 ¹H NMR을 통해 화학구조를 규명하였다. PCTN 공중합 폴리에스터는 TPA와 NDA의 함량에 따라 변화되는 광학특성을 보여주었고, 또한 PCTN 필름이 기존의 PET와 poly(ethylene naphthalate)(PEN) 필름과 비교하여 뛰어난 열특성 및 차단 특성을 보여주었다.

Keywords: copolyester, 1,4-cyclohexanedimethanol, 2,6-naphthalenedicarboxylic acid, melt polymerization, optical and barrier properties