화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Polymer(Korea), Vol.20, No.2, 280-287, March, 1996
Export Citation
교대 반복구조의 Poly(oxyalkylene-alt-oxynethylene) glycol을 이용한 열가소성 폴리우레탄의 합성과 열적물성
Synthesis and Properties of thermoplastic Polyurethane Elastomer Using Poly(oxyalkylene-alt-oxymethylene) glycos Composed of Asymmertric Alternating Units
김진봉, 최윤희, 김종근
초록
본 연구에서는 2∼6개의 메틸렌 단위를 갖는 diol과 dichloromethane을 상전이 촉매 조건하에서 친핵성 치환 반응을 시켜 교대 반복 구조의 poly(oxyalkylene-alt-oxymethylene) glycol을 합성하였다. Poly(oxyalkylene-alt-oxymethylene) glycol의 구조를 IR, NMR로 확인하였으며, 수평균 분자량은 GPC로 측정하였다. 또한 이들의 Tg, Tm, Tc를 DSC로 측정하였다. 합성된 poly(oxyalkylene-alt-oxymethylene) glycol을 소프트 세그먼트로 채용하여 열가소성 폴리 우레탄 탄성체 (TPU)를 합성하였고, 이들의 열적특성에 미치는 분자량 효과 및 구조 효과에 대해 연구하였다. TPU의 열적특성을 DSC로 측정한 결과 PEG, PPG, PTMG계 폴리우레탄에 비해 상당히 낮은 Tg를 나타내고 있으며 oxyalkylene 단위를 구성하는 메틸렌기의 수에 따라서 Tg의 고저반복 경향을 보이고 있다. 메틸렌기의 수가 짝수인 경우가 홀수인 경우보다 더 낮은 Tg를 나타내고 있다. 이러한 효과는 소프트 세그먼트내의 입체 배좌 구조에 따른 자유도 및 사슬의 운동성 변화로 해석되며 열가소성 폴리우레탄 탄성체에 적용시 저온 특성 조절효과를 보여주고 있다.
Poly(oxyalkylene-alt-oxymethylene) glycols were synthesized by reacting diols with dichloromethane in the presence of phase transfer catalyst under basic conditions. The molecular structures of poly(oxyalkylene-alt-oxymethylene) glycols were identified by IR, NMR and number average molecular weights were measured by GPC and Tg, Tc and Tm of this materials were measured by DSC. Thermoplastic polyurethanes(TPUs) were prepared by using poly(oxyalkylene-alt-oxymethylene) glycol as soft segments and MDI/BD as hard segments. We studied molecular weight effects and structural effects of poly(oxyalkylene-alt-oxymethylene) glycol affecting on thermal properties. Tg's of the TPUs measured by DSC were found to be much lower than those from conventional polyols such as PEG, PPG and PTMG. Besides, high and low alternating trends of Tg's were observed according to the number of methylene groups composing oxyalkylene units of polyols. Even numbered methylene groups lowered Tg more than odd numbered methylene groups did. These are considered as the conformational structural effects of soft segment chains affording variations of degree of freedom and chain mobility, Consequently low temperature thermal behaviors of TPUs could be controlled by the adoption of synthesized poly(oxyalkylene-alt-oxymethylene) glycols as soft segments.
Keywords:poly(oxyalkylene-alt-oxymethylene) glycol;thermoplastic polyurethane elastomer;thermal properties;chain mobility
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