• Journal of the Korean Applied Science and Technology
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• v.24 no.4
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• pp.393-398
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• 2007

We investigated heat stability of epoxy resin products and epoxy resin according to the influence hardener. The heat flow which shows the degree of thermal decomposition of the epoxy resin product and epoxy resin measured by using the differential scanning calorimeter (DSC). As a result, we found that in the case of heat stability for epoxy resin as hardener was added, the ratio of one to one (epoxy resin : hardener) was the most suitable in air condition and nitrogen atmosphere.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.424-430
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• 2011

A novel T-type polyurethane 7 containing 1-(2,5-dioxyphenyl)-2-(5-(1,2,2-tricyanovinyl)-2-thienyl)ethenes as NLO chromophores, which constitute part of the polymer backbone, was prepared. Polyurethane 7 is soluble in common organic solvents such as DMF and DMSO. It shows a thermal stability up to $270^{\circ}C$ from TGA thermogram with $T_g$ value obtained from DSC thermogram near $155^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of poled polymer film at 1560 nm fundamental wavelength is $3.56{\times}10^{-9}$ esu. Polymer 7 exhibits a thermal stability even at $5^{\circ}C$ higher than $T_g$, and no significant SHG decay is observed below $160^{\circ}C$, which is acceptable for nonlinear optical device applications.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.165-165
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• 2006

We prepared nonlinear optical (NLO) polymers possessing thermal and temporal stability, which were based on the polyimides appended with NLO chromophores. NLO chromophores with a terminal hydroxyl group have been synthesized by coupling between aminobenzene or julolidine donor and phenylene bridge, and then subsequent coupling between the resulting product and tricyanofuran acceptor. The chromophores were chemically bonded to the polyimides backbone through Mitsunobu reaction. The NLO polymers showed $160-170^{\circ}C$ of Tgs and were thermally stable up to $200^{\circ}C$. We obtained optical quality films by spincoating and evaluated their electro-optical properties and temporal stability.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.2
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• pp.83-89
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• 2010

Diamond-like carbon (DLC) coating was studied to be a good tribological problem-solver due to its low friction characteristics and high hardness. However, generally hydrogenated DLC film has shown a weak thermal stability above $300^{\circ}C$. However, the silicon doping DLC process by DC pulse plasma enhanced chemical vapor deposition (PECVD) for the new DLC coating which has a good characterization with thermal stability at high temperature itself has been observed. And we were discussed a process for optimizing silicon content to promote a good thermal stability using various tetramethylsilane (TMS) and methane gas at high-temperature. The chemical compositions of silicon-containing DLC film was analyzed using X-ray photoelectron spectroscopy (XPS) before and after heat treatment. Raman spectrum analysis showed the changed structure on the surface after the high-temperature exposure testing. In particular, the hardness of silicon-containing DLC film showed different values before and after the annealing treatment.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3190-3194
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• 2010

Mixed electrolytes formed by the combination of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP-TFSI) ionic liquid and standard liquid electrolyte are prepared and characterized. Linear sweep voltammetry measurements demonstrate that these mixed systems exhibit a wide electrochemical stability window, allowing them to be suitable electrolyte for carbonaceous anode-based lithium-ion batteries. Lithium-ion cells composed of graphite anode and $LiCoO_2$ cathode are assembled using the mixed electrolytes, and their cycling performances are evaluated. The cell containing proper content of BMP-TFSI shows good cycling performance comparable to that of a cell assembled with organic electrolyte. The presence of BMP-TFSI in the mixed electrolyte contributes to the reduction of the flammability of electrolyte solution and the improvement of the thermal stability of charged $Li_{1-x}CoO_2$ in the electrolyte solution.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1097-1100
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• 2009

New types of conducting polyaniline-polymannuronate (PANI-PM) composites were synthesized by in situ deposition techniques in an aqueous media. By dissolving different weight percentage of polymannuronate (PM) (5, 10, 15, and 25%), the oxidative polymerization of aniline was carried out using ammonium per sulfate as an oxidant. The obtained composites were studied for their thermal stability and electrochemical behavior. The thermal stability of PANI-PM composites is lower than PANI, which supports a strong interaction between PANI and PM. However, the composites show an appreciable electrochemical behavior. Based on these observation the PANI-PM composites can be explored in different fields such as electric devices, sensors, functional coatings, etc.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.308-311
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• 2012

A wide range of possible hazards existing in thermal batteries are mainly caused by thermal runaway, which results in overheating or explosion in extreme case. Battery separators ensure the separation between two electrodes and the retention of ion-conductive electrolytes. Thermal runaways in thermal batteries can be significantly reduced by the adoption of these separators. The high operating temperature and the violent reactivity in thermal batteries, however, have limited the introduction of conventional separators. As a substitute for separators, MgO powders have been mostly used as a binder to hold molten salt electrolyte. During recent decades the fabrication technology of ceramic fiber, which has excellent mechanical strength and chemical stability, has undergone significant improvement. In this study we adopted wet-laid nonwoven paper making method instead of the electrospinning method which is costly and troublesome to produce in volume. Polymeric precursor can readily be coated on the surface of wet-laid ceramic paper, and be formed into ceramic film after heat treatment. The mechanical strength and the thermo-chemical stability as well as the wetting behaviors of ceramic separators with various molten salts were investigated to be applicable to thermal batteries. Due to their excellent chemical, mechanical, and electrical properties, wet-laid nonwoven separators made from ceramic fibers have revealed positive possibility as new separators for thermal batteries which operate at high temperature with no conspicuous sign of a short circuit and corrosion.

• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.17-21
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• 2017

BACKGROUND: Castor oil and wormseed extract are important active ingredients for biopesticide, and ricinoleic acid in castor oil and three monoterpenes (ascaridole, carvacrol and p-cymene) in wormseed extract are known bioactive substances. However, their stabilities had not been studied, even though the stability was the core property for estimation of shelf-life of biopesticide. Aimed to investigate the thermal stabilities of the bioactive substances in castor oil and wormseed extracts. METHODS AND RESULTS: The contents of ricinoleic acid and three monoterpenes (ascaridole, carvacrol and p-cymene) were analyzed by gas chromatography (GC). The thermal stabilities of the bioactive substance were measured at $0^{\circ}C$, $23^{\circ}C$, $30^{\circ}C$, $40^{\circ}C$, $45^{\circ}C$ and $54^{\circ}C$ for 84 d. The half-lives of ricinoleic acid in biopesticides was ranged from 28.9 d to 57.8 d at $30^{\circ}C$, and the stability of pure castor oil were located in the range ($t_{1/2}$=46.2d for Indian product and 27.7 d for Korean product) at the same temperature. The half-lives of the total monoterpenes in biopesticides were ranged from 3.9 d to 27.7 d at $30^{\circ}C$. Among the monoterpenes, the stability ascaridole and p-cymene were decreased in acidic condition. All the bioactive substances showed similar stability on the different thermal conditions. CONCLUSION:The half-lives of most bioactive substance from castor oil and wormseed extracts were less than 100 d. To increase the stability of bioactive substance in biopesticide, stabilizing additives like antioxidant and oxygen remover should be considered to extend of the shelf-life.

• Journal of the Korean Chemical Society
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• v.19 no.1
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• pp.50-52
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• 1975

The oxidation stability of samples prepared by blending samples reported previously with diesel oil and diesel oil with additives(alkyl benzene and phenolic type of materials), was tested to study the mechanism of thermal oxidation stability of the regenerated lubricating oils. It was found that the improvement of thermal oxidation stability of such oils was caused by the formation of aromatic compounds, especially phenolic type of organic materials.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.663-668
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• 2001

Thermodynamic and electrical functions of aminophenol and anthranilic acid complexes with Mn(Ⅱ), Fe(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Cu(Ⅱ) were determined. ΔG°, ΔH° and ΔS° were calculated with the help of stability constant values at different temperatures. It was found that the complexing processes have an exothermic nature. The studied complexes behave like semiconductors. The conduction takes place according to hopping mechanism. To show the composition of complexes conductometric and photometric titrations, IR spectra, thermal analysis and X-ray diffraction techniques were employed.