Seong G. Kim  Ji W. Kim  Min S. Cho  Hyoung J. Choi  Myung S. Jhon 《应用聚合物科学杂志》2001,79(1):108-114

Dodecylbenzenesulfonic acid (DBSA)‐doped polyaniline particles were synthesized via emulsion polymerization, and electrorheological (ER) fluids were prepared by dispersing the synthesized polyaniline particles in silicone oil. The viscoelastic properties of DBSA‐doped polyaniline/silicone oil ER systems were examined using a vertical oscillation rheometer (VOR), which is designed for the rheological measurement of ER fluids, with a high voltage generator. Viscoelastic data obtained from the VOR were compared with those obtained from a commercial Physica rotational rheometer. The data from VOR were quite reliable in a broad range of both strain and frequency. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 108–114, 2001  相似文献   

    

Jongok Won  Myung Ho Kim  Yong Soo Kang  Hyun Chae Park  Un Young Kim  Sung Chang Choi  Seok Keun Koh 《应用聚合物科学杂志》2000,75(12):1554-1560

The surface carbonization of polyimide (PI) and polysulfone (PSf) by ion beam has been performed to adapt the carbon molecular sieve properties on the skin of the polymeric membranes without the deformation of the membrane structure. In order to control the structure of membrane skin and to improve gas transport properties, the irradiation conditions, such as the dosage and the source of ion beams, have been varied. The ideal separation factor of CO₂ over N₂ through the surface‐modified PI and PSf membranes increased threefold compared to those of the untreated, pristine membranes, whereas the permeability decreased with almost two orders of magnitude. This appears to be due to the fact that the structure of membrane skin has been changed to a barrier layer. The formation of barrier layer was confirmed by comparing the calculated values of a simple resistance model with the experimental results, and the estimated permeability of this barrier was 10⁻⁴ barrer. It was concluded that ion beam irradiation could provide a useful tool for improving selectivity for gas separation membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1554–1560, 2000  相似文献   

    

Myung‐Kwan Chun  Chong‐Su Cho  Hoo‐Kyun Choi 《应用聚合物科学杂志》2004,94(6):2390-2394

Poly(vinyl pyrrolidone) (PVP)/poly(acrylic acid) (PAA) interpolymer complexes were prepared, in ethanol or dimethylformamide (DMF), by template polymerization of acrylic acid in the presence of PVP (MW: 42.5 or 1100 K) used as the template. FTIR analysis showed that the complexes were formed through hydrogen bonding between the carboxyl groups of the PAA and the carbonyl groups of the PVP. The glass‐transition temperature (T_g) of the complex, prepared in ethanol, was higher than that of the component polymers, whereas the T_g of the complex, prepared in DMF, was located between that of the component polymers. The dissolution rate of the complex was affected by the molecular weight of the PVP and the reaction solvent. The release rate of ketoprofen from the complexes showed a pH dependency, and was slower at a lower pH. The ketoprofen release rate from the complex was controlled mainly by the dissolution rate of the complex above the pK_a of PAA (4.75) and by the diffusion rate below the pK_a. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2390–2394, 2004  相似文献   

    

Hyoung J. Choi  Hong J. Lee  Sung T. Lim  Myung S. Jhon 《Polymer Engineering and Science》1999,39(3):469-473

The rod-climbing constants of kaolinite-suspended polyisobutylene (PIB) solutions are investigated from rod-climbing experiments. For a low deformation rate, this particle suspended polymer solution can be regarded as a second-order fluid, and the rod-climbing constant for such fluids is correlated with the rheological properties of the particle-suspended polymer solutions. The rod-climbing constants for kaolinite suspended PIB solutions were found to decrease with temperature and increase with PIB concentration, molecular weight of PIB, solvent viscosity, and particle concentration. The rheological properties were measured using rotational rheometer, and the shear viscosity and the first normal stress difference of the kaolinite suspended PIB solution show the Boger-fluid characteristics.  相似文献   

    

Ji Mun Kim  Myung Geun Jang  Dong Hyup Park  Woo Nyon Kim 《应用聚合物科学杂志》2016,133(35)

The effects of compatibilizer on the morphological, thermal, mechanical, and rheological properties of poly(methyl methacrylate) (PMMA)/poly(N‐methyl methacrylimide) (PMMI) (70/30) blends were investigated. The compatibilizer used in this study was styrene–acrylonitrile–glycidyl methacrylate (SAN‐GMA) copolymer. Morphological characterization of the PMMA/PMMI (70/30) blend with SAN‐GMA showed a decrease in PMMI droplet size with an increase in SAN‐GMA. The glass‐transition temperature of the PMMA‐rich phase became higher when SAN‐GMA was added up to 5 parts per hundred resin by weight (phr). The flexural and tensile strengths of the PMMA/PMMI (70/30) blend increased with the addition of SAN‐GMA up to 5 phr. The complex viscosity of the PMMA/PMMI (70/30) blends increased when SAN‐GMA was added up to 5 phr, which implies an increase in compatibility between the PMMA and PMMI components. From the weighted relaxation spectrum, which was obtained from the storage modulus and loss modulus, the interfacial tension of the PMMA/PMMI (70/30) blend was calculated using the Palierne emulsion model and the Choi‐Schowalter model. The results of the morphological, thermal, mechanical, and rheological studies and the values of the interfacial tension of the PMMA/PMMI (70/30) blends suggest that the optimum compatibilizer concentration of SAN‐GMA is 5 phr. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43856.  相似文献   

    

Min Taek Kim  Soonho Song  Yoo Jin Yim  Myung Wook Jang  Gookhyun Baek 《Propellants, Explosives, Pyrotechnics》2015,40(5):779-785

The infrared irradiance signature from exhaust plume is essential for the design of solid rocket motors. To overcome the difficulty of conducting experiments using real rocket motors, experimental studies were carried out to compare standard rocket motors and real rocket motors of the same propellant. The static firing tests on standard and real rocket motors of NEPE and HTPB propellants were conducted. Despite different rocket motor size and methodology of spectro‐radiometric measurement, the spectral characteristics of the infrared irradiance signature for both rocket motors were quite similar. The standard and real rocket motors of HTPB propellant showed similar tendency of steady infrared irradiance emission throughout the combustion, whereas both rocket motors of NEPE propellant showed a rapid emission in the midstream of combustion. The total infrared irradiance of NEPE was about 55 % less than that of HTPB propellant for both standard and real rocket motor experiments. Additionally, the relative amounts of chemical products produced during propellant combustion came out to be similar for both rocket motors. The experimental results indicated that the spectral characteristics of infrared irradiance and combustion products were quite similar for different sized rocket motors of same propellant and that a correlation of infrared irradiance signature exists between small‐sized standard rocket motors and real rocket motors. Thus, the spectral characteristics of real rocket motors could be reasonably estimated from the results of standard rocket motors.  相似文献   

    

Dong‐Hwan Lee  Yingjie Qian  Ji‐Hoon Park  Jong‐Suk Lee  Sang‐Eun Shim  Myung‐Jong Jin 《Advanced Synthesis u0026amp; Catalysis》2013,355(9):1729-1735

A β‐diketiminatophosphane‐palladium complex was found to act as an efficient and general catalyst in the Stille coupling reaction of various aryl and heteroaryl chlorides with organostannanes. The results show that this catalytic system allows for the use of less reactive substrates such as deactivated or sterically hindered aryl chlorides. A catalyst loading of 0.5 mol% was sufficient to achieve excellent performance under relatively mild reaction conditions. Furthermore, the scope of catalyst was extended to the coupling of vinyl chlorides.  相似文献   

    

Qi Chen  Lifeng Zhang  Myung‐Keun Yoon  Xiang‐Fa Wu  Ragib H. Arefin  Hao Fong 《应用聚合物科学杂志》2012,124(1):444-451

In this study, electrospun glass (structurally amorphous SiO₂) nanofibers (EGNFs) with diameters of ～ 400 nm were incorporated into epoxy resin for reinforcement and/or toughening purposes; the effects of silanization treatment (including different functional groups in silane molecules) and mass fraction of EGNFs on strength, stiffness, and toughness of the resulting nano‐epoxy composite resins were investigated. The experimental results revealed that EGNFs substantially outperformed conventional glass fibers (CGFs, with diameters of ～ 10 μm) in both tension and impact tests, and led to the same trend of improvements in strength, stiffness, and toughness at small mass fractions of 0.5 and 1%. The tensile strength, Young's modulus, work of fracture, and impact strength of the nano‐epoxy composite resins with EGNFs were improved by up to 40, 201, 67, and 363%, respectively. In general, the silanized EGNFs with epoxy end groups (G‐EGNFs) showed a higher degree of toughening effect, while the silanized EGNFs with amine end groups (A‐EGNFs) showed a higher degree of reinforcement effect. The study suggested that electrospun glass nanofibers could be used as reinforcement and/or toughening agent for making innovative nano‐epoxy composite resins, which would be further used for the development of high‐performance polymer composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

    

Dong‐Hwan Lee  Young‐Jun Kwon  Myung‐Jong Jin 《Advanced Synthesis u0026amp; Catalysis》2011,353(17):3090-3094

This communication reports on the β‐diketiminatophosphane palladium‐catalyzed copper‐free Sonogashira coupling of aryl chlorides with alkynes. A catalyst loading of 0.5 mol% is sufficient to achieve high performance under relatively mild reaction conditions. Furthermore, dialkynylbenzenes are efficiently prepared by one‐pot double Sonogashira couplings of aryl dichlorides.  相似文献   

    

Mei Chen Jim  Nguyen Dang Hung  Jae Myung Yoo  Mee Ree Kim  Dai‐Eun Sok 《European Journal of Lipid Science and Technology》2012,114(2):114-122

Lysophosphatidylcholine (lysoPC) with polyunsaturated fatty acyl chains has been known to be anti‐inflammatory in vivo. In the present study, we examined the effect of docosahexaenoyl‐lysophosphatidylcholine (DHE‐lysoPC) and 17‐hydroxydocosahexaenoyl‐lysophosphatidylcholine (17‐HDHE‐lysoPC) on spleen weight and cytokine level in spleen of mice treated with lipopolysaccharide (LPS). For this purpose, mice were administrated i.p. with DHE‐lysoPC or 17‐HDHE‐lysoPC 1 h before i.p. injection of LPS. First, DHE‐lysoPC (50–400 µg/kg) was found to suppress the LPS‐induced increase of spleen weight dose‐dependently, and such a suppressive effect was greater for 17‐HDHE‐lysoPC, compared to DHE‐lysoPC. Next, in an attempt to see the effect of DHE‐lysoPC on cytokine levels in spleen of mice treated with LPS, DHE‐lysoPC was found to suppress LPS‐induced increase in the levels of cytokines such as TNF‐α, IL‐1β, or IL‐6 in a dose dependent manner (50–400 µg/kg), in contrast to DHA showing a significant action at a high dose (400 µg/kg) only. The greater suppressive effect of 17‐HDHE‐lysoPC (15–150 µg/kg) than DHE‐lysoPC suggested that action of DHE‐lysoPC may be enhanced through lipoxygenation process. Presumably in support of this, when the interval time between 17‐HDHE‐lysoPC administration and LPS challenge was varied, the cytokine‐suppressing effect was found to be augmented in a time‐dependent manner. Taken all together, it is suggested that DHE‐lysoPC and 17‐HDHE‐lysoPC may be beneficial in suppressing the inflammation in spleen tissue.  相似文献