• Macromolecular Research
• /
• 제15권2호
• /
• pp.160-166
• /
• 2007

Novel multiblock copolymers, based on segmented sulfonated hydrophilic-hydrophobic blocks, were synthesized and investigated for their application as proton exchange membranes. A series of segmented sulfonated poly(arylene ether sulfone)-b-polyimide multiblock copolymers, with various block lengths, were synthesized via the coupling reaction between the terminal amine moieties on the hydrophilic blocks and naphthalene anhydride functionalized hydrophobic blocks. Successful imidization reactions required a mixed solvent system, comprised of NMP and m-cresol, in the presence of catalysts. Proton conductivity measurements revealed that the proton conductivity improved with increasing hydrophilic and hydrophobic block lengths. The morphological structure of the multiblock copolymers was investigated using tapping mode atomic force microscopy (TM-AFM). The AFM images of the copolymers demonstrated well-defined nanophase separated morphologies, with the changes in the block length having a pronounced effect on the phase separated morphologies of the system. The self diffusion coefficient of water, as measured by $^1H$ NMR, provided a better understanding of the transport process. Thus, the block copolymers showed higher values than Nafion, and comparable proton conductivities in liquid water, as well as under partially hydrated conditions at $80^{\circ}C$. The new materials are strong candidates for use in PEM systems.

• 콘크리트학회논문집
• /
• 제26권4호
• /
• pp.457-463
• /
• 2014

이 연구는 화학혼화제 인수검사 기준으로 활용할 수 있는 고형분량 변동이 콘크리트 품질에 미치는 영향에 대해 살펴보는데 그 목적을 두었다. 현재 한국도로공사의 잠정기준으로 운용 중인 ASTM C 494 기반의 고형분량 변동범위 ${\pm}12%$는 혼화제의 종류 및 고형분량의 특성을 반영하지 못해 혼화제 종류에 따라 상이하게 나타났다. 고형분량 변동에 따른 콘크리트의 품질 변동을 평가한 결과 리그닌은 감수율이 낮은 관계로 고형분량의 변동범위가 큰 반면 나프탈렌계 및 폴리칼본산계 고성능감수제는 높은 감수율로 인하여 인수검사 기준으로 활용 중인 고형분량의 차이에 대한 허용범위 재조정이 요구되었다.

• Advances in concrete construction
• /
• 제9권4호
• /
• pp.345-354
• /
• 2020

Cement is the most significant component in concrete. Large scale manufacturing of cement consumes more energy and release harmful products (Carbon dioxide) into the atmosphere that adversely affect the environment and depletes the natural resources. A lot of research is going on in globally concentrating on the recycling and reuse of waste materials from many industries. A major share of research is focused on finding cementitious materials alternatives to ordinary Portland cement. Many industrial waste by-products such as quartz powder, metakaolin, ground granulated blast furnace slag, silica fume, and fly ash etc. are under investigations for replacement of cement in concrete to minimize greenhouse gases and improve the sustainable construction. In current research, the effects of a new generation, ultra-fine material i.e., alccofine which is obtained from ground granulated blast furnace slag are studied as partial replacement by 25% and with varying amounts of sulfonated naphthalene formaldehyde (i.e., 0.3%, 0.35% and 0.40%) on mechanical, water absorption, thermal and microstructural properties of concrete. The results showed moderate improvement in all concrete properties. Addition of SNF with combination of alccofine showed a significant enhancement in fresh, hardened properties and water absorption test as well as thermal and microstructural properties of concrete.