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Topologically Close-Packed Structures in High-χ PDMS-b-PTFEA Copolymers
전승배,전태석,이상우,이병두,류두열 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
We introduce a new access to complex low-symmetry Frank-Kasper phases using linear-type high-χ and high-ε block copolymers, where χ and ε are the Flory-Huggins interaction parameter and conformational asymmetry between the two blocks, respectively. Polydimethylsiloxane-b-poly(2,2,2-triflouroethyl acrylate) (PDMS-b-PTFEA) copolymers were precisely synthesized by adjusting the volume fraction of minor PTFEA block (fPTFEA) in the same PDMS block. Using SAXS measurements, we systematically explore the packing structures in the space of temperature versus fPTFEA. As fPTFEA decreases, the sphere-packing phase behavior exhibits the composition dependence of the non-classical sphere-packing phases (A15, σ, and C14) and classical body-centered cubic (BCC) phase. The experimental sequence of sphere-packing phases agrees with the theoretical thermodynamic phase stability of A15-σ-C14-BCC with decreasing fPTFEA, which are subject to both high-χ and high-ε nature of PDMS-b-PTFEAs.
냉각면이 있는 정방형내 이종유체의 저온거동에 관한 실험적 연구
전승배,장원택,김병철 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1
Two stratified fluids (water and spindle oil) in aspect ratio of 1 to 1 were studied experimentally with the variation of an initial temperature and a cooling surface temperature in the square cavity with a lower cooling surface. With the initial temperature being varied, a cooling surface temperature were varied. With supercooling phenomenon being processed, a latent heat was emitted. The temperature of the spindle oil was increased with the occurrence of the latent heat. In case of initial temperature was low. the supercooling phenomena were observed and continued up to the end of experimental.