• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.169-173
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• 2009

In this study, We were studied on the properties of polyurethane elastomer containing the polyol, chain extender and isocyanate in polyurethane elastomer. Polyurethane elastomer had the best properties with poly(tetramethylene) glycol for in-line skate wheel. With more incorporation of chain extender content in polyurethane elastomer, tensile strength and hardness increased and elongation decreased. And then properties of polyurethane elastomer with the bulky type isocyanate had better than the flexible type isocyanate.

• Macromolecular Research
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• v.16 no.7
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• pp.596-603
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• 2008

To improve the mechanical properties, dimensional stability and blood compatibility, the biomedical material $Pellethene^{(R)}$ was blended with multiblock polyurethane (MPU) containing phospopholipid/long alkyl chain (C-18) at the various MPU contents and crosslinked using dicumyl peroxide as a crosslinking agent. The maximum MPU content for stable $Pellethene^{(R)}$/MPU blended films was approximately 30 wt%. The optimum crosslinking agent content and crosslinking time with respect to the mechanical properties were 4 wt% and 3 h, respectively. The mechanical properties (tensile strength and elongation at break) and water absorption of the crosslinked blend film increased with increasing MPU content. The test of platelet adhesion on the surfaces of the crosslinked blend film showed a decrease in the level of platelet adhesion from 70% to 6% with increasing MPU content from 0 to 30 wt%. These results suggest that the crosslinked $Pellethene^{(R)}$/MPU-30 (MPU content: 30 wt%) sample has strong potential as a novel material for blood compatible material applications.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.109-117
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• 2011

In this study, we experimented that how influence chain extension to waterborne urethane-epoxy hybrid resin for leather garment coatings. First of all, We had analyzed datas by FT-IR, SEM and machanical properties. By instruments analysis measurement we confirmed that synthesis of epoxy and hybrid resin. In this experiment we knew that polyurethane-epoxy hybrid resin have 5 grades of solvent resistance. Tensile strength measured in the polyurethane-epoxy resin(EDA 5.37g, 2.386 $kg_f/mm^2$) had the most strong strength.. Also polyurethane-epoxy hybrid resin had better result(EDA 5.37g. 37.4 mg. loss) than other hybrid resins. As hight proportion of EDA in hybid resin, we obtained low elongation and low flexibility. In this result, chain extension of waterborne polyurethane-epoxy hybrid resin showed that how effect in leather coating by ratio of EDA.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.711-718
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• 2014

In this paper, the mechanical property change was investigated by adding 1,4-butanediol as chain extender of polyurethane dispersion for leather coating. Reagents for the synthesis were polypropylene glycol(PPG), isoporon diisocyanate(IPDI), dimethylolpropionic acid(DMPA) and 1,4-BD. All samples showed good solvent resistance and flexibility by different content of the 1,4-BD. As results, samples which contains a lot of 1,4-BD showed good properties whth strength of $1.80kg_f/mm^2$ and abrasion test measurement of 49.54 mg.loss. According to elongation test, the sample which contains low amount of 1,4-BD was good property as 364 %.

• Elastomers and Composites
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• v.57 no.1
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• pp.13-19
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• 2022

Polycarbonate diol-based waterborne polyurethane (WPU) was prepared by prepolymer mixing process. The prepolymer mixture contained the polycarbonate diol, isophorone diisocyanate (IPDI), dimethylol propionic acid, triethylamine, and ethylenediamine (EDA). The NCO/OH ratio in the prepolymer was adjusted by controlling the molar ratio of IPDI, and its effects on the properties of WPU were studied. The structure of WPU was characterized by fourier transform infrared spectroscopy. The average particle size increased and viscosity decreased with increasing NCO/OH ratio and EDA content in WPU. The reduced phase separation between soft and hard segments increased glass transition temperature. The reduction in the thermal decomposition temperature could be attributed to the low bond energy of urethane and urea groups, which constituted the hard segment. Additionally, the polyurethane chain mobility was restricted, elongation decreased, and tensile strength increased. The hydrogen bond between the hard segments formed a dense structure that hindered water absorption.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1235-1242
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• 2019

In this study, prepolymer was synthesized through the reaction of isoporon diisocyanate (IPDI) and dimethylolbutanoic acid (DMBA) based on poly (tetramethylene ether) glycol (PTMG) for the synthesis of water-soluble polyurethane to be used as a leather surface coating applied with ethyl acetate and piperazine. Thereafter, the piperazine was chain-extended with 0.01 M, 0.03 M, 0.05 M, and 0.07 M in the water-dispersed resin, and the tensile strength, elongation, CV (cyclic voltammetry), and solvent resistance analysis were performed. Tensile strength of the prepared sample was measured at 5.422 kg_f/㎟ when the piperazine content was 0.07M, and elongation was measured as 587% when the piperazine was 0.01M. Solvent resistance analysis showed the same solvent resistance regardless of piperazine content, and the redox potential was changed according to piperazine content through CV measurement.

• Elastomers and Composites
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• v.50 no.1
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• pp.24-29
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• 2015

In this study, we investigated the effects of a crosslinking agent and a compatibilizer on the mechanical and rheological properties of waste PP and waste ground rubber tire (WGRT) composites. In order to simulate a commercial TPV, the component of waste PP and WGRT was fixed at 30 and 70 wt%, respectively. With the simple addition of SEBS-g-MA into the waste PP/WGRT composites, the tensile strength of the composite was decreased, whereas both the elongation at break and impact strength were significantly increased because of rubbery characteristics of SEBS-g-MA. In order to further improve the properties of the composites, the waste PP/WGRT/SEBS-g-MA composites was revulcanized with dicumyl peroxide (DCP). As expected, mechanical properties of the revulcanized composites was generally improved. Especially, with 15 and 1 phr of SEBS-g-MA and DCP, elongation at break was highest value of about 183% because of the recross-linking of WGRT without chain scission of the main chain. It was found that complex viscosity of the revulcanized composite increased which might verify further vulcanization of the WGRT.

• Journal of Microbiology and Biotechnology
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• v.31 no.11
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• pp.1533-1544
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• 2021

n-Caproic acid (CA) is gaining increased attention due to its high value as a chemical feedstock. Ruminococcaceae bacterium strain CPB6 is an anaerobic mesophilic bacterium that is highly prolific in its ability to perform chain elongation of lactate to CA. However, little is known about the genome-wide transcriptional analysis of strain CPB6 for CA production triggered by the supplementation of exogenous lactate. In this study, cultivation of strain CPB6 was carried out in the absence and presence of lactate. Transcriptional profiles were analyzed using RNA-seq, and differentially expressed genes (DEGs) between the lactate-supplemented cells and control cells without lactate were analyzed. The results showed that lactate supplementation led to earlier CA p,roduction, and higher final CA titer and productivity. 295 genes were substrate and/or growth dependent, and these genes cover crucial functional categories. Specifically, 5 genes responsible for the reverse β-oxidation pathway, 11 genes encoding ATP-binding cassette (ABC) transporters, 6 genes encoding substrate-binding protein (SBP), and 4 genes encoding phosphotransferase system (PTS) transporters were strikingly upregulated in response to the addition of lactate. These genes would be candidates for future studies aiming at understanding the regulatory mechanism of lactate conversion into CA, as well as for the improvement of CA production in strain CPB6. The findings presented herein reveal unique insights into the biomolecular effect of lactate on CA production at the transcriptional level.

• Elastomers and Composites
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• v.44 no.3
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• pp.308-314
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• 2009

The acrylic rubber was synthesized by emulsion polymerization using n-butyl acrylate, n-butyl methacrylate, acrylonitrile, glycidylmethacrylate, and allyl methacrylate. When the contents of acrylonitrile were increased at fixed amount of crosslinking monomers, the Tg of polymers was increased with the contents of acrylonitrile, Mooney viscosity, hardness, and tensile strength also were increased. But the elongation was decreased due to the reduction of chain flexibility. The addition of the monomer for crosslinking, glycidylmethacrylate whose Tg is $56^{\circ}C$ resulted in the increased Tg of the polymer, and increased Mooney viscosity, hardness, and tensile strength, but the elongation at break was decreased with the glycidylmethacrylate contents. It was shown that this phenominon was attributed to the increment of crosslinking density by glycidylmethacrylate through the measurement of rheometer.

• Proceedings of the Korean Society of Rheology Conference
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• 2001.06a
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• pp.11-14
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• 2001

Our study have aimed to identify the deformation and breakup mechanism of minor phase in polymer blends under uniaxial enlongational flow. Experimentally, we measured the transient elongational viscosity of PS/HDPE blends using the uniaxial elongational rheometer at two temperatures. And we observed the evolution of blend morphology with elongation time. Morphological change was observed by quenching the specimen after deformation. If the viscosity variation of PS was compared with that of HDPE at each temperature, PS showed larger temperature dependence than HDPE. At 155$^{\circ}C$, the dispersed phase of larger size were easily affected by affine deformation. The initial spherical shape changed to flat ellipsoid at first, then flat ellipsoid to bulbous shape, and bulbous to thin thread and its satellites. But dispersed phase of smaller size showed the change from sphere to ellipsoid. At 175$^{\circ}C$, the dispersed phase were mostly deformed from spherical shape to ellipsoid. As a result, the morphological change of dispersed phase in elongational deformation is affected by chain flexibility and viscosity ratio. We need to further study to make sure the mechanism of elongation of viscoelastic polymer blends.