• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2425-2433
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• 2018

This study investigates a new organic based material and its dielectric and mechanical properties. It is a comprehensive nanocomposite comprising a combination of various types of nanofillers with hydrophobic silica nanoparticles (AEROSIL R 974) as a matrix modifier and a polyamide nano nonwoven textile, Ultramid-Polyamide 6, pulped in the electrostatic field as a dielectric barrier. The polymer matrix is an epoxy network based on diglycidyl ether of bisphenol A (DGEBA) and cycloaliphatic diamine (Laromine C260). The designed nanocomposite material is an alternative to the conventional three-component composites containing fiberglass and mica with properties that exceed current electroinsulating systems (volume resistivity on the order of $10^{16}{\Omega}{\cdot}m$, dissipation factor tan ${\delta}=4.7{\cdot}10^{-3}$, dielectric strength 39 kV/mm).

• Membrane Journal
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• v.24 no.4
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• pp.317-324
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• 2014

It is very well known that the conventional polyamide (PA) thin film composite (TFC) reverse osmosis (RO) membranes have excellent permselective properties, but their chlorine tolerance is not good enough. In this study, to improve such chlorine tolerance, microporous membranes containing hydrophilic functional groups such as -COOH were used as a support to prepare PA TFC RO membranes, employing the conventional interfacial polymerization method. Meta-phenylene diamine (MPD) and 2,6-diamine toluene (2,6-DAT) were used as diamine monomers and tri-mesoyl chloride (TMC) as an acid monomer. The membranes prepared were characterized using various instrumental analytical methods and permeation test set-up. The flux obtained from the membranes prepared so was more than $1.0m^3/m^2day$ at 800 psi of operating pressure, while the salt rejection was over 99.0%. The chlorine tolerance of them was also found to be better than that of the membrane prepared by using conventional polysulfone support without hydrophilic functional groups.

• Composites Research
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• v.32 no.6
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• pp.375-381
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• 2019

Multiwalled carbon nanotubes (MWCNTs) are covalently functionalized with isocyanates by directly reacting commercial hydroxyl functionalized MWCNTs with excess 4,4'-methylenebis (phenyl isocyanate) (MDI) and hexamethylene diiosocyanate (HDI). HDI-modified MWCNTs results in a higher surface isocyanate density than MDI-modified MWCNTs. Anionic ring-opening polymerization of ε-caprolactam is conducted using a sodium caprolactam initiator in combination with a di-functional hexamethylene-1,6-dicarbamoylcaprolactam activator in the presence of isocyanate functionalized MWCNTs. This polymerization proceeds in a highly efficient manner at relatively low reaction temperature (150℃) and short reaction times (10 min). During the polymerization, the isocyanate functionalized MWCNTs act not only as reinforcing fillers but also as second activators. Nanocomposites with HDI modified MWCNTs exhibit higher reinforcement and faster isothermal crystallization than MDI modified MWCNTs. The results show that PA6 chains grow more effectively from HDI modified MWCNT surface than from MDI modified MWCNT surface, resulting in stronger interaction between PA6 and MWCNTs.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.682-689
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• 1999

In this study, binary PA 6,6/EPM(or EPM-g-MA) blends and ternary PA 6,6/EPM/EPM-g-MA blends were fabricated according to the variation in elastomer content and composition ratio of blend, and mixing temperature and rate so as to investigate the degree of influence of elastomer content and average particle size, morphology, and distribution of dispersed elastomer on properties of blends. As results, under the constant mixing rate(250 rpm) and different five section temperature profiles(270-265-265-255-$255^{\circ}C$) in extruder, high notched Izod impact strength was the property of PA 6,6/EPM-g-MA(70/30) blend among binary blends. Notched Izod impact strength of this blend was 25 times improvement compared with that of polyamide 6,6. In addition, elastomer average particle size of ternary PA 6,6/EPM/EPM-g-MA(70/15/15) blend was $0.56{\mu}m$, which was fine distribution, and notched Izod impact strength of that blend was the highest of all blends prepared with the variation in elastomer content. But the properties of this ternary blend were decreased remarkably at the diverse mixing temperatures and mixing rates.

• Elastomers and Composites
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• v.55 no.4
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• pp.339-346
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• 2020

We functionalized a wear-resistant carbon-based MoS2 filler to solve its limited wear condition problem. The filler exhibits excellent lubricative properties. The surface modification of MoS2 was carried out using a (3-glycidyloxypropyl)trimethoxysilane (GPTMS) silane coupling agent to improve the low compatibility and dispersibility of the filler that generally degrade the performance of composites. A silane coupling agent was employed for the functionalization of MoS2, and its effect on the wear resistance of MoS2/Polyamide-6,6 was investigated. The silanization of MoS2 was identified by contact angle analysis and Fourier-transform infrared, energy dispersive X-ray, and X-ray photoelectron spectroscopies. The wear resistance of the composite was found to be improved significantly by the surface functionalization of MoS2.

• Elastomers and Composites
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• v.28 no.4
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• pp.283-292
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• 1993

The morphology and impact strength of alloys of high density polyethylene(HDPE) and nylon-6(PA) with modified $ethylene-{\alpha}-olefin$ copolymer(OCP) as compatibilizer and impact modifier were measured by the scanning electron microscope(SEM) and the notched Izod impact test(and the high rate impact test), respectively. HDPE is incompatible with PA and specimens obtained from simple mechanical mixing show the inferior properties. However, it was indicated that OCP played roles of not only impact modifier but also compatibilizer. High rate impact test results were different from those of the notched Izod impact test, but in both tests OCP was effective for HDPE/PA blends. From SEM observation, the size of the dispersed phase in alloys prepared with OCP is much smaller than that of alloys without OCP and the interfacial adhesion of alloys prepared with OCP is also better. Toughening mechanism of polymer blends was discussed by combining the morphology analysis with mechanical and thermal properties.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.818-824
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• 2019

In the present work, we determined the gamma-ray attenuation characteristics of eight different polymers(Polyamide (Nylon 6) (PA-6), polyacrylonitrile (PAN), polyvinylidenechloride (PVDC), polyaniline (PANI), polyethyleneterephthalate (PET), polyphenylenesulfide (PPS), polypyrrole (PPy) and polytetrafluoroethylene (PTFE)) using transmission geometry utilizing the high resolution HPGe detector and different radioactive sources in the energy range 81-1333 keV. The experimental linear attenuation coefficient values are compared with theoretical data (WinXCOM data). The linear attenuation coefficient of all polymers reduced quickly with the increase in energy, at the beginning, while decrease more slowly in the region from 267 keV to 835 keV. The effective atomic number of PVDC and PTFE are comparatively higher than the $Z_{eff}$ of the remaining polymers, while PA-6 possesses the lowest effective atomic number. The half value layer results showed that PTFE ($C_2F_4$, highest density) is more effective to attenuate the gamma photons. Also, the theoretical results of macroscopic effective removal cross section for fast neutrons ($\sum_{R}$) were computed to investigate the neutron attenuation characteristics. It is found that the $\sum_{R}$ values of the eight investigated polymers are close and ranged from $0.07058cm^{-1}$ for PVDC to $0.11510cm^{-1}$ for PA-6.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1518-1523
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• 2013

To estimate the shelf life of red cabbage sprouts (stored at 4 and $10^{\circ}C$), the numbers of total aerobic bacteria were determined during storage. Parameters for the Gompertz model were determined and the shelf life was predicted using a modified Gompertz equation. The estimated shelf lives of red cabbage sprouts packed with polyolefin film and polyamide/polyamide/polyethylene (PA/PA/PE) film at $4^{\circ}C$ were 49.4 and 52.3 h, respectively, whereas those of red cabbage sprouts packed with polyolefin film and PA/PA/PE film at $10^{\circ}C$ were 19.7 and 22.6, respectively. The shelf life prediction equation was appropriate, based on the statistical analysis of the accuracy factor, bias factor, and mean square error. On the other hand, for red cabbage sprouts treated with aqueous $ClO_2$/fumaric acid and UV-C then packed with polyolefin film or PA/PA/PE film, the shelf life was predicted to be longer than 168 h. These results suggest that the combined treatment of aqueous $ClO_2$/fumaric acid and UV-C can be useful for improving microbial safety and extending the shelf life of red cabbage sprouts during storage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.877-887
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• 2015

We have proposed a new method for estimating the viscosity of the composite. In this paper, we have developed a device for measuring the injection mold cavity pressure. This makes it possible to verify the accuracy of the viscosity in CAE D/B in real time by measuring the melt pressure in the mold, and comparing this with the simulated pressure from the CAE analysis. Materials used in this study is a PP(Polypropylene), PP/LGF30%(Polypropylene/long glass fiber 50% composite) and PA66/LGF50%(Polyamide 6,6/long glass fiber 50% composite). The viscosity data for PP and PP long fiber composite have already been built, but the one for PA66 long-fiber composite does not exist because it is a newly developed material. Thus we obtained the viscosity curve of PA66/LGF50% by this system. Then, the viscosity curves from conventional viscometer were also compared with the viscosity obtained by the our method. And, we proved the accuracy of the CAE data of PP. In case of PP/LGF50% which is highly viscous and complex material, we improved the existing CAE data.because there was a difference between the measuring data and the CAE data.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1141-1146
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• 1999

Melt blend of PA6/PP-g-MA system containing SEBS-g-MA as a compatible impact modifier was prepared to investigate the change of mechanical properties and morphologies. The tensile strength slightly decreased, but the elongation at break increased with increasing content of SEBS-g-MA in the blend. Also the notched izod impact strength increased with increasing the content of PP-g-MA and SEBS-g-MA. It is attributed to improved compatibilization and interfacial adhesion by reaction of the amide of PA6 with maleic anhydride of SEBS-g-MA and PP-g-MA. The result of dynamic mechanical analysis(DMA) showed a typical behavior of the compatibilization in the polymer blends. Finally, in the phase structure observed by the use of SEM, we confirmed improvement of the compatibilization and interfacial adhesion with increasing the content of SEBS-g-MA and PP-g-MA.