• Macromolecular Research
• /
• 제13권3호
• /
• pp.243-252
• /
• 2005

The effect of the vinyl acetate (VA) content on the thermal, viscoelastic, rheological, morphological and mechanical behaviors in various blends of ethylene-vinyl acetate (EVA)/ethylene-$\alpha$-olefin copolymers was investigated using 28, 22 and $15 mol\%$ of VA in EVA. In the DSC melting and crystallization thermograms of all of the EVA systems blended with ethylene-$\alpha$-olefin copolymers, discrete peaks were observed which were related to the constituents. In the dynamic mechanical thermal analysis, the storage modulus increased with increasing content of ethylene-$\alpha$-olefin copolymers. In addition, the transition regions relating to the tan bpeaks varied with the VA content. The crossover point between G' and G" varied depending on the VA contents, and shear-thinning was more prominent in the EVA/EtBC system. In the SEM investigation, a discrete phase morphology was observed in both the EVA/EtBC and EVA/EtOC blends, but the contrast improved with decreasing VA content. However, the tensile strength and modulus improved, but the elongation at break reduced with decreasing VA content, implying that the ethylene-$\alpha$-olefin copolymers play the role of reinforcing materials. Thus, the EVA and ethylene-$\alpha$-olefin components in the copolymers are immiscible in the molten and solid states, but are nevertheless mechanically compatible.

• Bulletin of the Korean Chemical Society
• /
• 제33권4호
• /
• pp.1199-1203
• /
• 2012

Catalytic filters consisting of Ni nanoparticle and carbon fiber with different oxidation states of Ni (either metallic or oxidic) were prepared using a chemical vapor deposition process and various post-annealing steps. CO oxidation reactivity of each sample was evaluated using a batch type quartz reactor with a gas mixture of CO (500 mtorr) and $O_2$ (3 torr) at $300^{\circ}C$. Metallic and oxidic Ni showed almost the same CO oxidation reactivity. Moreover, the CO oxidation reactivity of metallic sample remained unchanged in the subsequently performed second reaction experiment. We suggested that metallic Ni transformed into oxidic state at the initial stage of the exposure to the reactant gas mixture, and Ni-oxide was catalytically active species. In addition, we found that CO oxidation reactivity of Ni-oxide surface was enhanced by increase in the $H_2O$ impurity in the reactor.

• Macromolecular Research
• /
• 제10권6호
• /
• pp.325-331
• /
• 2002

Phase behavior of a PEO-PPO-PEO (Pluronic P103) triblock copolymer in water is investigated using small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and rheology. Pluronic P103 shows apparent two gel states in different temperature regions. The first sol-to-gel transition at a lower temperature (i.e., the hard gel I state) turns out to be the hexagonal microphase as evidenced by the combined SANS and SAXS and the frequency dependence of both G′ and G" in rheology. In contrast to the hard gel I, the second sol-to-gel transition (i. e., the hard gel II state) at a higher temperature represents the block copolymer micelles in somewhat disordered state rather than the ordered state seen in the hard gel I. Moreover, turbidity change depending only on the temperature with four distinct regions is observed and the large aggregates with size larger than 5,000 nm are detected with DLS in the turbid solution region. Based upon the present study, two different gelation mechanisms for aqueous PEO-PPO-PEO triblock copolymer solutions are proposed.

• 한국가스학회지
• /
• 제2권1호
• /
• pp.90-98
• /
• 1998

미래의 화재 사고에 대한 구체적인 대응과 사고를 줄이기 위하여 국내외 사고사례의 집적과 체계적인 자료 분류가 필요하다. 본 연구에서는 화재 사고사례 분류 모델을 제시하고 미국 NFPA의 분류 모델과 일본의 모델을 비교하여 향후 개선 방향을 제시하였다. 또한 PC의 Windows 환경에서 운영될 수 있는 사고사례에 관한 데이터베이스 프로그램(FADBS)을 개발하여 사고사례 분석을 쉽고 효과적으로 활용할 수 있도록 하였다.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2001년도 춘계학술대회 논문집
• /
• pp.10-14
• /
• 2001

Physical chemistry states that electric potential is due to Gibb's free energy from chemical reaction of the electric cell. However we have not the electromagnetic meaning of Gibb's free energy. the free energy is discovered to be a kinetic energy part of the rotating electromagnetic wave ($\pi$-ray), which is different from conventional Coulomb attraction energy and can anticipate that there is a current difference between before and after the electric load. This paper manipulates the relationship between $\pi$-rays (Gibb's free energy) and electrolysis, cell reaction and brown gas reaction.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2000년도 추계종합학술대회
• /
• pp.656-660
• /
• 2000

In general, the silo blender is composed of silo, blending cone and vane. This study is to develop the blending system for resin of industrial materials produced in the chemical plant By examining closely the How states at the six flow zones of different geometry in the blender due to the gravity of resin, it is possible to develop the silo blender by the optimum design through the sin and the capacity change.

• 약학회지
• /
• 제16권2호
• /
• pp.108-112
• /
• 1972

S-Trifluoroacetoxy-trihalomethyl mercaptans were prepared by reacting metal salt of trihaloacetic acid with perhalomethyl mercaptans in the closed vessel. And besides, certain decomposed states of these products by heat and U.V. were studied by Infra red, N.M.R., molecular weight determination and chemical analysis methods. The results showed that the more fluorine substituted compounds were more stable than the less fluorine substituted ones.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2006년도 제31회 학술논문발표회 초록집
• /
• pp.166-166
• /
• 2006

• Journal of Photoscience
• /
• 제12권1호
• /
• pp.47-50
• /
• 2005

Mediumeffects have been explored on the competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl-substituted phenyl ketones. The chemical selectivities of photochemical reactions of silylalkyl phenyl ketones appear to depend on medium polarity, medium silophilicity, added metal cation and alkyl length. Irradiations of silylalkylketones in aqueous solvent system and in presence of metal cation such as $Li^+$ and $Mg^{+2} $lead to formation of acetophenone predominantly by the sequential SET-silyl transfer route.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
• /
• pp.228-229
• /
• 2000

Magnetic Fe nanoparticles were synthesized by CVC process using Fe(CO)$\sub$5/ as precursors. The nanoparticles have core-shell structures with uniform dispersion. For the specific purposes, the micostructures as well as the magnetic states of Fe nanoparticles can be controlled by adjusting the process parameters, such as the carrier gases, the decomposition temperature, the cooling of powder, etc.