• Textile Coloration and Finishing
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• v.31 no.3
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• pp.165-176
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• 2019

Polyurethane-ureas(PUUs) were prepared from 4,4'-methylenebis(cyclohexyl isocyanate) and various diols including isosorbide. Isosorbide is starch-derived monomer that exhibit a wide range of glass transition temperature and are therefore able to be used in many applications. PUU was synthesized by a pre-polymer polymerization using a catalyst. Successful synthesis of the PUU was characterized by fourier transform-infrared spectroscopy. Thermal properties were determined by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. It was found that by tuning isosorbide content in the resin, their glass transition temperature(Tg) slightly decreased. Physical properties were also determined by tensile strength and X-ray diffraction. There is no significant differences between petroleum-derived diol and isosorbide in XRD analysis. Moreover, their physical and optical properties were determined. The result showed that the poly(tetramethylene ether glycol)/isosorbide-based PUU exhibited enhanced tensile strength, transmittance, transparency and biodegradability compared to the existing diols. After 11 weeks composting, the biodegradability of blends increased in ISB-PUU. The morphology of the fractured surface of blend films were investigated by scanning electron microscopy.

• Journal of Adhesion and Interface
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• v.8 no.4
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• pp.1-7
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• 2007

Waterborne polyurethane (WPU) which is environment friendly has been rapidly used in coating and adhesive industries. However, the WPU is deficient in chemical resistance, thermal resistance, and mechanical property compared to solvent-based polyurethane. In this study, the WPU was synthesized from two types of polyester polyols, 4,4-dicyclohexylmethane diisocyanate ($H_{12}MDI$), dimethylolpropionic acid (DMPA), triethylamine (TEA) and ethylenediamine (EDA), organophilic nanoclay. The thermal stability, mechanical property of the WPU nanocomposite dispersion increased with increasing clay concentration. Especially, their peel strength showed their maximum value at 3 wt% of organophilic nanoclay contents.

• Elastomers and Composites
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• v.43 no.1
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• pp.1-7
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• 2008

Far-infrared vulcanization of ethylene-propylene-diene terpolymer(EPDM) compounds has been studied in comparison with hot air vulcanization. Vulcanization characteristics of EPDM compounds were measured by degree of curing and temperature of specimens in vulcanization process. As a result, degree of curing by far-infrared of EPDM compounds was shown to be higher value than that by hot air at the same vulcanization temperature. Especially, degree of curing by far-infrared on 3 mm thickness of EPDM compounds was increased by two times compared to that by hot air. While the increase of thermal conductivity of EPDM compounds highly improved degree of curing by far-infrared, that hardly improved degree of curing by hot air.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.46-51
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• 2019

Intermittent CSR testing was used to investigate the degradation of a NBR O-ring, and also the prediction of its life-time. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. Degradation of O-rings by thermal aging was observed between $40^{\circ}C$ and $120^{\circ}C$. O-rings showed non-linear degradation behavior under $80^{\circ}C$. At 20% of failure condition, predicted life-times were 32.5 years by Arrhenius plot and 22.6 years by WLF plot.

• Composites Research
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• v.35 no.5
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• pp.309-316
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• 2022

The demand for cold-resistant cable material is increasing due to the rapid increase in the development of devices that operate in a low temperature environment. Cold tolerance of a thermoplastic polymer largely depends on the type and content of about 20 or more additives used to make the polymer. The phenomenon of polymer hardening at low temperature can be classified into hardening by simple temperature effect, embrittlement at the glass transition temperature, and hardening by crystallization of polymers that tend to crystallize. In this study, a thermoplastic polymer having a low glass transition temperature, a flame retardant, and an additive were mixed to evaluate the mechanical properties of a thermoplastic polymer composite material for electric wires. It has been confirmed that mechanical properties and processability are determined depending on the additives and compatibilizers added, and this study is considered to be useful as basic data for optimization to meet the performance requirements of wires developed for low-temperature use.

• Journal of Adhesion and Interface
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• v.13 no.3
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• pp.116-120
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• 2012

In this study, waterborne polyurethane was prepared from polyester polyol, $H_{12}MDI$, DMPA and sulfopropylated polypropyleneglycol-${\alpha}$,${\omega}$-diamine (SP). The $T_g$ of waterborne polyurethane was increased as the SP content increased, while it was decreased at the NCO/OH ratio of 1.8. Also the hydrolysis-resistance and tensile strength were increased as the SP content increased. The tensile strength decrement of WPU-SP was 2~5% with the exception of WPU-SP-1.

• Journal of Adhesion and Interface
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• v.17 no.4
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• pp.136-140
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• 2016

In this study, a series of dimer acid-based polyamides with different diamines were synthesized by condensation polymerization and the polyamides were characterized by Fourier transform infrared spectroscopy (FT-IR). Effects of diamine structures on mechanical and thermal properties of polyamides were investigated. The tensile strength and lap shear adhesion strength of aromatic-based polyamide (DAP) were higher than those of aliphatic-based polyamide (DAH). In DSC thermogram, DAP has a high $T_g$ and $T_m$ compared with DAH. DAP's and DAH's softening point were $112-115^{\circ}C$ and $98-121^{\circ}C$, respectively.

• Elastomers and Composites
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• v.48 no.4
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• pp.256-262
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• 2013

We synthesized thermoplastic polyurethane elastomer (TPU) with different contents of sulfuric acid group, and characterized their physical properties such as mechanical, thermal and grip properties. And the results were compared with carboxylic acid-introduced TPU. Wet slip, tensile strength and abrasion properties were increased by the introduction of acid group. Mechanical properties increased with increasing the acid content up to 0.3 wt%. However, wet slip was continually increased as the acid content increased due to increase of hydrophilicity of TPU.

• Elastomers and Composites
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• v.51 no.3
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• pp.212-217
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• 2016

Influence of poly(ethylene-co-vinyl acetate) (EVA) types and cure systems on cure characteristics of foaming EVA compounds were investigated. Three kind EVAs with different VA contents were employed. Influence of triallyl cyanurate (TAC) and dicumylperoxide (DCP) content on the cure characteristics were examined. The minimum torque ($T_{min}$) and delta torque (${\Delta}T$) decreased as the VA content increased. The ${\Delta}T$ was increased by adding TAC and by increasing the DCP content. For the foaming EVA compounds without TAC, the cure times such as the minimum cure time ($t_{min}$), scorch time ($t_2$), and optimal cure time ($t_{90}$) did not show a specific trend according to the DCP contents. For the foaming EVA compounds containing TAC, the cure times decreased as the DCP content increased. From the experimental results, it was found that efficienct DCP/TAC ratio for improvement of the crosslink density was 1.1~2.0.

• Elastomers and Composites
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• v.49 no.3
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• pp.191-198
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• 2014

We synthesized thermoplastic polyurethane elastomer(TPU) with acid group and nano zinc oxide, and characterized their mechanical properties, thermal properties, contact angle and grip property. The effects of the zinc oxide content and size on the physical property of TPU were investigated. When the nano zinc oxide was introduced in TPU with acid group, it had excellent mechanical properties and grip by formation of hydrogen and ionic bonding. The wet slip of TPU with zinc oxide was increased continuously as ionization rate increased due to increase of hydrophilicity and ionic interaction, and mechanical properties were increased with increasing ionization rate up to 50%.