The binary random copolyesters of poly(ethylene succinate-co-ethylene terephthalate) (PES/PET) were synthesized and their sequence distributions were investigated over the entire range for copolyester compositions by 1^H-NMR spectroscopy. in the case of PES/PET copolymers. the theoretical melting points predicted by Flory's melting depression equation based on the assumption that the crystal is formed only in one part of PES or PET in the case of PBS/PBT system were not fitted to the experimental melting points. From the result of X-ray diffractogram, PES/PET could be cocrystallized by the incorpation of PES into PET crystallize at the PET-rich composition, but it was thought that the incoporation of PET into PES at the PES-rich composition was difficult because of the blockiness of copolyesters at that composition, which was determined by the degree of randomness.

이성분계 랜덤공중합물인 poly(ethylene succinate-co-ethylene terephthalate) (PES/PET)를 합성하였으며, ¹H-NMR 분광기를 이용하여 전 조성범위에 걸쳐 sequence 분포를 조사하였다. 이러한 공중합물의 융점강하 거동을 예측한 결과, PET 공중합물의 경우에는 PBS/PBT의 경우와 마찬가지로 결정이 어느 한쪽에 의해서 단독적으로 이루어 진다고 보고 Flory의 융점강하 이론에 응용하였을 때 실제 측정된 융점과 잘 일치하지 않았다. X-선 회전패턴을 분석한 결과, PET의 조성이 풍부한 부분에서는 일부 PES가 PET결정내로 연합하여 공결정화가 형성되지만, PES의 조성이 풍부한 부분에서는 B(degree of randomness)값을 측정한 결과 블록경향이 강하여 PET의 PES 결정내로의 연합이 어렵다고 보았다.

Keywords: poly(ethylene succinate-co-ethylene terephthalate); sequence distribution; degree of randomness