• Polymer(Korea)
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• v.24 no.3
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• pp.314-325
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• 2000

Thermal degradation of thermoplasitc polyurethane modified polycarbonate has been investigated by means of DSC, GPC and FT-IR techniques. The polyurethanes used in this study are TPU-35 and TPU-53 containing 35.5 and 53.4 wt% of hard segments, respectively. The more content of hard segment, the higher the glass transition temperature (T$_{g}$) of TPU was observed. On the other hand, the T$_{g}$ of the TPU modified PC decreased with the content of TPU and the annealing temperature regardless of the hard segment contents. The latter behavior nay arise from the thermal degradation of TPU upon annealing process: the observed thermal degradation temperatures were at 240 and 25$0^{\circ}C$ for the PC/TPU-35 and PC/TPU-53, respectively. The molecular weight, molecular weight distribution and viscosity agree well with the DSC measurement, which implicates a thermal degradation of TPU. In addition, thermal stability of the TPU modified PC linearly decreased with an incorporation of TPU. Transesterification or any interaction was not observed using FT-IR: the evidence was no frequency shift or any variance betwere the carbonyl stretching and NH group. For the specimens prepared below the degradation temperature, the enhancement of the thickness dependent impact strength of the PC/TPU blend was observed, and the morphology of the two blends was compared.d.

• Tribology and Lubricants
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• v.24 no.1
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• pp.7-13
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• 2008

In this work, a simple and low cost sensor technique is proposed to test oil color in real time using in-line sensor. It is presented to use a ratio of intensity in red wavelength range to intensities of green and blue wavelength ranges (defined as a 'chromatic ratio') in order to estimate the oil color change. The proposed sensor technique is realized by irradiating a white LED as light source and a RGB color sensor as photoreceiver, and the chromatic ratio of various types of used oils are measured. The results show that chromatic ratio generally reflects chemical deterioration of oil, including oil oxidation and thermal degradation. It is concluded that the proposed sensor could be used for an effective oil monitoring technology.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.360-367
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• 2005

PMMA has been used extensively worldwide as industrial and construction materials due to its excellent material properties. When PMMA is subject to thermal degradation, unit of monomers are detached from polymer chain and this phenomena is called unzip reaction. Therefore, PMMA thermally degrades into its monomer. Characteristics of thermal degradation of PMMA has been investigated using TGA in this research as a basic study for recovery of MMA.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.22 no.1
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• pp.15-23
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• 2016

Gelatin soft capsules, manufactured by the press through package(PTP) process, are widely used in the production of multivitamin dietary supplements and other health functional foods. Gelatin capsules can prevent light and air from having a direct contact with the contents in the capsule, and the nutrients inside the capsules are preserved without any loss. In the present study, on the basis of the results on the safety of gelatin capsules. The parameters investigated included degradation of the capsules before their shelf life, capsule deformation, and changes in specific nutrients. Moisture and heat in the production and storage environments of the capsules caused the gelatin to swell and attach some of the inorganic salts in the vitamin contents. Nutritional component analysis showed that B1, B5, B9, and B12 contents were decreased, while mineral elemental analysis shown calcium, chloride, and zinc compound were found to be infused into the gelatin of the capsule shell.

• Journal of the Korean Chemical Society
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• v.16 no.2
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• pp.100-105
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• 1972

The thermal degradation of poly (${\alpha}$-methyl styrene) in several mixed solvents (toluene-n-butylalcohol, toluene-sec-butylalcohol, toluene-kerosene, toluene-methyl ethyl ketone) without hydroquinone, and in with the addition of the hydroquinone, was studied at temps. of $165^{\circ}{\sim}205^{\circ}C$. The velocity constant of degradation (k), and the activation energy (E) were calculated for each solvent. As results, k decreased with the increase of the volume-fraction of poor solvent in both systems, whereas E either showed no perceptible change or it increased with the volume-fraction of poor solvents. these results were discussed.

• Journal of Applied Reliability
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• v.17 no.1
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• pp.66-71
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• 2017

Purpose: Polymer capacitors are known to have very high reliability as compared with liquid electrolytic capacitors, but their capacity has been reported to decrease in charge and discharge at low temperature. The purpose of this study to clarify these characteristics. Methods: In order to clarify these characteristics, charging-discharging tests were carried out for 200 hours with three different capacities and at 5 different temperature from $5^{\circ}C$ to $100^{\circ}C$. Results: As a result of the test, it was confirmed that the capacity of the polymer capacitor was decreased with higher capacity and lower temperature. Conclusion: Such a failure phenomenon was caused by the shrinkage and expansion characteristics of the polymer used therein, it is presumed that this failure phenomenon is due to the complex pore structure made by etching.

• Textile Coloration and Finishing
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• v.29 no.3
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• pp.148-154
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• 2017

Many researches have been made on the processing technology of Poly(ethylene terephthalate) (PET), which is widely used for clothing and non-clothing applications. In this study, we coated PET filaments with m-aramid resin to improve heat resistance and antimicrobial properties. In order to enhance adhesion between PET and m-aramid polymer, the adhesive polymer was coated on the PET filaments using a winding speed of 100m/min and then treated with m-aramid. Scanning electron microscopy was used to analyze the surface of the adhesive polymer and m-aramid treated PET filament. The change of initial degradation temperature according to treatment was confirmed by thermogravimetric analysis. Antimicrobial activity analysis using bacterial reduction method showed that PET filament treated with adhesive polymer and m-aramid had an increased antibacterial effect compared to untreated PET filament.

• Polymer(Korea)
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• v.28 no.6
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• pp.545-550
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• 2004

The refractive index of thin copolymer film was controlled by photo-degradation of chromophores in the copolymer. FTIR and UV/Vis spectroscopy were employed to elucidate the effect of chemical structure on refractive index changes after photobleaching. The decrease of refractive index of the film by photobleaching can be ascribed to the decrease of polarizability of polymer molecules through breakage of C =C bond in the chromophore. Due to the selective photoreaction of the chromophores which align along the film plane, refractive index of the copolymer film measured in TE mode decreases faster than that in TM mode. Polarized ATR-FTIR spectroscopy was used to verify such a difference in refractive index of the film.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2290-2295
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• 2018

An acceleration stress test (AST) was performed to evaluate the durability of a polymer membrane in a polymer electrolyte membrane fuel cell (PEMFC) for 500 hours. Previous studies have shown that hydrogen crossover measured by linear sweep voltammetry (LSV) increases when the polymer membrane deteriorates in the AST process. On the other hand, hydrogen crossover of the membrane often decreases in the early stages of the AST test. To investigate the cause of this phenomenon, we analyzed the MEA operated for 50 hours using the AST method (OCV, RH 30% and $90^{\circ}C$). Cyclic voltammetry and transmission electron showed that the electrochemical surface area (ECSA) decreased due to the growth of electrode catalyst particles and that the hydrogen crossover current density measured by LSV could be reduced. Fourier transform infrared spectroscopy and thermogravimetric/differential thermal analysis showed that -S-O-S- crosslinking occurred in the polymer after the 50 hour AST. Gas chromatography showed that the hydrogen permeability was decreased by -S-O-S- crosslinking. The reduction of the hydrogen crossover current density measured by LSV in the early stages of AST could be caused by both reduction of the electrochemical surface area of the electrode catalyst and -S-O-S- crosslinking.

• Polymer(Korea)
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• v.38 no.3
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• pp.320-326
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• 2014

The effects of high shear rate processing on the thermal properties of PC/ABS blends were studied. It was executed by the high shear processing machine (NHSS2-28) at the varied conditions of screw speeds and loaded duration. After the samples were processed with NHSS2-28, the $T_gs$ were shifted from 143 to $133^{\circ}C$, and the behavior of degradation determined by TGA showed two distinct steps before high shear rate processing, while it showed a straight line after the processing. In order to provide the reasons of the properties, it was showen by SEM and UTM that the droplet sizes morphologically decreased after the processing, and the elongations decreased slightly until 1000 rpm of screw speed and then sharply decreased, according to the conditions of high shear rate processing. Therefore, it can be confirmed that $T_g,s$ of PC/ABS blends were considerably shifted under an appropriate high shear rate condition, and rapidly dropped, so that blends degraded above the condition, due to stress-induced degradation.