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Supramolecular polymer nanocomposites with self-healing effects
장영욱,( Muhammad Kashif ) 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Self-healing polymers (SHPs) can repair damage (scratches, cracks) on the application of a stimulus, and provide extended application lifetime and reduced maintenance cost. One approach to prepare SHPs is the use of dynamic interactions, which may be supramolecular (hydrogen bonding, ionic interactions, π-π stacking, metal-ligand coordination) or dynamic covalent bonds. These structurally dynamic polymers show rearrangement in their structure in response to a stimulus. The healing process in the polymers is externally stimulated by heat, water or light. In this study, we found that supramolecular hydrogen bonded elastomer, which can be prepared by crosslinking of semicrystalline maleated polyolefin elastomer (mPOE) with 3-amino-1,2,4-triazole (ATA), can exhibit a thermal healing properties. Further, ATA crosslinked elastomer/ octadecylamine modified graphene oxide nanocomposites show the healing effects under near infrared (NIR) irradiation along with enhanced mechanical properties of the elastomer matrix.
Effects of Copper on the Corrosion Properties of Low-Alloy Steel in an Acid-Chloride Environment
장영욱,홍지현,김정구 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4
The influence of Cu addition on the corrosion resistance of low-alloy steel in an acid-chloride solution was investigated by electrochemical methods, such as potentiodynamic polarization tests and an electrochemical impedance spectroscopy (EIS). The XPS analysis of the corroded surfaces indicated the formation of protective Cu2O and Cu(OH)2 layers on the surface. The formation of Cu products on the surface reduced the uniform corrosion rate of the steel, but promoted localized corrosion due to the galvanic interaction between the covered areas of copper oxide/hydroxide and the uncovered areas on the surface of steel. The influence of Cu addition on the corrosion resistance of low-alloy steel in an acid-chloride solution was investigated by electrochemical methods, such as potentiodynamic polarization tests and an electrochemical impedance spectroscopy (EIS). The XPS analysis of the corroded surfaces indicated the formation of protective Cu2O and Cu(OH)2 layers on the surface. The formation of Cu products on the surface reduced the uniform corrosion rate of the steel, but promoted localized corrosion due to the galvanic interaction between the covered areas of copper oxide/hydroxide and the uncovered areas on the surface of steel.
유기용제가 무정형 폴리에스테로공중합체의 물성에 미치는 영향
장영욱,조희민 한국공업화학회 1999 응용화학 Vol.3 No.1
A study has been carried out to see the effect of solvent sorption on the mechanical properties of amorphous copolyesters. Sorption and desorption curves indicated that, among the solvents investigated, N,N-dimethylformamide(DMFA) was sorbed greatly by the copolyesters. The effect of solvent environments on the mechanical properties of amorphous copolyesters have been studied by means of the tensile test. From the mechanical behaviour of copolyesters before and after sorption, we found that change of the mechanical properties of copolyesters is explained on the basis of the plasticization, solvent induced crystallization, surface cavitation, and chemical attack.
Jews and Koreans in the USSR: Patterns after the Dissolution of the Soviet Union
장영욱 전남대학교 글로벌디아스포라연구소 2019 디아스포라 연구 Vol.13 No.2
This paper seeks to find the reasons for the contrast migration behaviours of two remarkably similar ethnic groups, Soviet Jews and Soviet Koreans. Mill’s Method of Difference is adopted to analyse the differences between these two groups. While as many as 600,000 Soviet Jews went to their newly founded national state, Israel, during the post-Soviet transition period, few Soviet Koreans left for Korea which was then equally advanced as Israel in terms of economic growth. After exploring the similar push and pull factors faced by both peoples, three possible explanations for their different repatriation patterns, namely income differentials, migrant network, and repatriation policy, are suggested. Economic concerns did trigger the mass migration of Soviet Jews but given that the Koreans had similar economic benefits of emigration, the role of economic factors may have been limited. A formerly established community of immigrants from the Soviet Union in Israel and the unique repatriation policy represented by the Law of Return and “absorption baskets” appear to have exerted a bigger influence on decisions of prospect migrants. The impact of these two factors is made more convincing because Korea had neither previous migrant stock from the former Soviet Union countries nor the policies to attract their compatriots abroad.
장영욱,Joon-Phil Eom,Jae-Gu Kim,Hee-Taik Kim,Dong-Kook Kim 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.2
Shape memory polymer networks were prepared from blends of end-carboxylated telechelic poly(ecaprolactone) (XPCL) and epoxidized natural rubber (ENR). The XPCL/ENR blends can form cross linked structure via interchain reaction between the reactive groups of each polymer during molding at high temperature. Degree of crosslinking of the blend network and their thermomechanical properties were characterized by gel content measurement, DSC and DMA. We found that the degree of crosslinking and crystalline melting transition temperatures was dependent upon the blend compositions as well as the molecular weight of the XPCL segment in the blends. The blends showed a good shapememory behavior such as good shape fixity as well as a high final recovery rate when they exhibit crystalline melting transition with a sufficiently high degree of crosslinking. And the response temperature of the recovery was well matched with Tm of the samples.
장영욱,Geumsig Shin 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.4
Organic–inorganic hybrid crosslinked membranes based on poly(ethylene glycol) (PEG) and sulfonated polyhedral oligomeric silsesquioxane (POSS-SO3H) with urethane crosslinks were prepared as candidate materials for a proton exchange membrane for direct methanol fuel cells (DMFC). Infrared (FT-IR)spectroscopy and ion exchange capacity measurements for the hybrid revealed the POSS is incorporated as a part of the crosslinked network. We found that proton conductivity increased and methanol permeability decreased with increasing POSS content in the hybrid membrane. In particular, our hybrid membranes demonstrated proton conductivities comparable to that of Nafion 117 while exhibiting lower methanol permeability as compared to Nafion 117. We postulate that the polar sulfonic acid groups of the incorporated sPOSS cages assemble to provide ion conduction paths while the hydrophobic portions of the same sPOSS cages combine to form a barrier to methanol permeation of the hybrid membrane.