Article
  • Broad Line Nuclear Magnetic Resonance Relaxations of Aromatic Copolyesters
  • Jin JI, Chang JH, Lim AR
  • 방향족 코폴리에스테르의 넓은선 핵자기 공명 완화시간에 관한 연구
  • 진정일, 장진해, 임애란
Abstract
Broad line nuclear magnetic resonance (NMR) measurements have been made for a series of the random as well as the ordered sequence copolyesters having the same overall compositions. The aromatic, random copolyesters were prepared in melts from terephthalic acid(TERE) , diacetoxynaphthalene(DAN) isomers and p-acetoxybenzoic acid(ABA) in the mole ratio of TERE : DAN : ABA= 1 : 1 : 2. The corresponding ordered sequence copolyesters also were prepared to have a regular sequence in the order of terephthalic acid (TERE)-p-hydroxybenzoic acid(POB) -naphthalenediol(NAPH)- p-hydroxybenzoic acid(POB) moieties. Naphthalenediol isomers used in this study are the 1,6-, 2,6- and 2,7-derivatives. NMR spectra of copolyesters were obtained at 6 MHz in the temperature range of 180∼460K (-93∼187℃). Spin-lattice relaxation time(T1) of 2,6-polymer was significantly shorter than those of the others, regardless of the comonomer sequence, due to its linear molecular structure. The temperatures where minimum in T1 was observed coincide very well with the glass transition temperatures(Tg) of the respective copolyesters determined by differential scanning calorimetry(DSC). The 1,6-polymer having an ordered sequence was unique in that it did not show any T1 because of saturation phenomenon. The values of spin-spin relaxation time(T2), however, were not dependent much on the polymer structures.

같은 조성을 갖는 일정서열 코폴리에스테르와 마구잡이 코폴리에스테르를 합성하였고, 이에 대하여 넓은선 핵자기 공명행동을 조사하였다. 마구잡이 공중합체들은 테레프탈산, 디아세톡시나프탈렌 이성질체들과 p-아세톡시 벤조산을 각각 1 : 1 : 2의 몰비율로 용융중합하여 얻었으며, 이에 대응하는 일정서열 공중합체는 테레프탈산-p-히드록시벤조산-나프탈렌디올-p-히드록시벤조산순의 일정서열을 갖도록 합성하였다. 이때 사용된 나프탈렌디을 이성질체들은 1,6-, 2,6-와 2,7-디올이었다. 공중합체의 NMR 스펙트럼은 180-460 K(-93∼l87℃)의 온도범위에서 6 MHz로 측정하여 얻었다. 2,6-중합체의 스핀-격자 완화시간(T1)은 직선형의 분자구조 때문에 단위체의 서열에 불구하고 다른 것들에 비해 매우 짧았다. T1 곡선에서 최소값을 나타낼때의 온도는 시차주사열분석기(DSC)에 의해 결정된 공중합체들의 유리전이온도(Tg)와 잘 일치하였다. 그러나 규칙서열 1,6-중합체의 경우는 포화현상때문에 T1값을 측정할 수 없었다. 스핀-스핀 완화시간(T2)의 값들은 중합체의 구조에 별 영향을 받지 않았다.

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  • Polymer(Korea) 폴리머
  • Frequency : Bimonthly(odd)
    ISSN 0379-153X(Print)
    ISSN 2234-8077(Online)
    Abbr. Polym. Korea
  • 2023 Impact Factor : 0.4
  • Indexed in SCIE

This Article

  • 1990; 14(3): 250-256

    Published online Jun 25, 1990