A series of copolyesters were prepared by post-copolymerizing PET with mixtures of 2-bromoterephthalic acid and 1,5-diacetoxynaphthalene. Thermal and liquid crystalline properties of the copolymers were examined by differential scanning calorimetry and by observation on the hot-stage of a polarizing microscope. The copolyesters exhibited two Tg''s. Those containing less than 50 mole % PET unit were found to be thermotropic. Wide angle X-ray analysis of the copolyesters was performed and it was found that inclusion of as low as 20 mole % of 2-bromoterephthalic acid and 1,5-naphthalenediol moieties completely destroyed PET crystalline structure. Chemical and IR spectroscopic analyses of chloroform extractable and unextractable fractions suggest that copolyesters prepared are heterogeneous in composition and consist of fractions with differing compositions.

PET를 2-브로모테레프탈산 및 1,5-디아세톡시나프탈렌과 반응시켜 일련의 공중합체를 합성하였다. 이들 공중합체의 열적성질과 액정성을 DSC 및 편광 현미경 분석법으로 행하였다. 공중합체 모두 두개의 Tg를 보여 주었으며, PET단위의 함량이 50mole% 보다 적을 때는 액정성을 나타냈다. 광각 X-선 분석결과에 의하면 2-브로모테레프탈산과 1,5-나프탈렌디올 잔기의 함량이 20mole% 만 되어도 PET의 결정구조는 완전히 파괴되었다. 공중합체를 클로로포름으로 용출하여, 가용분과 분용분을 원소분석 및 IR분석을 행하여 보니 공중합체의 조성이 불균일함을 알았다.