• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 추계 총회 및 학술발표회
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• pp.69-70
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• 1997

Polyimides and related polymers, when synthesized from aromatic monomers, have generally rigid chain structures resulting in a low gas permeability. The rigidity of polymer chains reduces the segmental motion of chains and works as a good barrier against gas transport. To overcome the limit of use as materials of gas separation membranes due to low gas permeability, block copolymers with the incorporation of flexible segments like siloxane linkage and ether linkage have been studied. These block copolymers have microphase-separated structures composed of microdomains of flexible poly(dimethylsiloxane) or polyether segments and of rigid polyimides segments. In case of rigid-flexible block copolymers, the characteristics of both phases for gas permeation are of great difference. The permeation of gas molecules occurs favorably through microdomains of flexible segments, whereas those of rigid segments hinder the permeation of gas molecules. Accordingly the increase of content of flexible segments in a rigid polymer matrix will increase the gas permeability of the membrane linearly. However, this prediction does not satisfy enough many experimental results and in particular the drastic increase of the permeability is observed in a certain volume fraction. It was proposed that the gas transport mechanism is dominated by diffusion rather than gas solubility in a certain content of flexible phase if solution-diffusion mechanism is adopted. However, the transition from solubility-dependent to diffusion-dependent cannot be explained by the understanding of mechanism itself. Therefore, we consider an effective chemical path which permeable phase can form in a microheterogenous medium, and percolation concept is introduced to describe the permeability transition at near threshold where for the first time a percolation path occurs. The volume fraction of both phases is defined as V$_{\alpha}$ and V$_{\beta}$ in block copolymers, and the volume of $\beta$ phase in the threshold forming geometrically a traversing channel is defined as V$_{\betac}$. The formation mechanism of shortest chemical channel is schematically depicted in Fig. 1.

• 공업화학
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• 제24권3호
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• pp.305-313
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• 2013

본 연구는 glycidyl azide polymer (GAP)계 에너지 함유 열가소성 폴리우레탄 탄성체(energetic thermoplastic polyurethane elastomers, ETPE)를 합성한 후 탄성체의 필름 제조 공정의 열처리 조건이 물성에 미치는 영향에 대하여 고찰하였다. GAP계 ETPE는 ATR-FTIR, DSC, 그리고 DMA를 이용하여 분석하였다. GAP계 ETPE의 물성에 대한 열처리 조건의 영향은 $80{\sim}130^{\circ}C$의 온도 범위에서 1 h과 24 h의 열처리 시간을 나누어 연구를 진행하였다. 1 h의 열처리 조건에서는 $130^{\circ}C$의 열처리 온도에서 그리고 24 h의 열처리 과정에서는 $105^{\circ}C$ 이상의 온도조건에서 아자이드기의 흡수대인 $2090cm^{-1}$ 피크의 감소가 관찰되었으며, methylene chloride와 dimethylformamide 용매에 대한 필름의 용해도 또한 감소하였다. 이것은 $100^{\circ}C$ 이상 열처리 온도조건이 아자이드기의 가교 부반응을 유도할 수 있음을 나타낸다. 또한 열처리 온도가 $80^{\circ}C$에서 $110^{\circ}C$로 증가함에 따라 온도변화에 따른 저장 탄성률 곡선의 고온 고무평탄 영역이 더 높은 온도까지 확장되었으며, 이 또한 가교반응의 결과이다.