• 폴리머
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• 제39권1호
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• pp.1-5
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• 2015

The effects of zeolite on the thermal stability of poly(vinyl chloride) (PVC) were investigated by the static thermal stability test, pyrolysis experiment and ultraviolet spectrum. The results showed that the porous zeolite could absorb hydrogen chloride (HCl), which suppressed the catalysis of HCl on thermal degradation of PVC, thus improved the thermal stability of PVC. The oxidizing acid which was loaded on zeolite had oxidated on the double bond that formed during the dehydrochlorination of PVC. This process could prohibit the growth of the conjugated polyene and improved the color of PVC. Hence, zeolite might be possible to come up with a high performance thermal stabilizer.

• 한국안전학회지
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• 제24권4호
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• pp.40-46
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• 2009

The early identification of thermal hazards associated with a process such as the heats of reaction, exothermic decompositions, and the understanding of thermodynamics before any large scale operations are undertaken. The evaluation of reaction factors and thermal behavior on esterification process in manufacture of concrete mixture agents are described in the present paper. The experiments were performed in the differential scanning calorimetry(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). The aim of the study was to evaluate the thermal stability of single material and mixture in esterification process. We provided the thermal data of chemical materials to present safe operating conditions through this study.

• 한국응용과학기술학회지
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• 제23권4호
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• pp.362-367
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• 2006

This paper describes the experiments for investigating the effects of thermal stability of several commercial carpet mate materials. The melting point and thermal decomposition temperature was measured by means of a differential scanning calorimeter(DSC) in air condition. The DSC data and burning test results of nylon bulked continuous filament(N-BCF) yarn 100%, nylon(NY), polypropylene(PP), and a new material named polytrimethyleneterephthalate(PTT) were analysed to obtain the effect on their thermal stability. Conclusively, we observed that PTT and PP were approximately $380^{\circ}C$ and $240^{\circ}C$ to start the thermal decomposition, respectively. In other words, PTT is thermally the most stable material for carpet manufacturing.

• 한국미생물·생명공학회지
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• 제19권1호
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• pp.100-108
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• 1991

Molecular characteristics and improving methods for thermal stability of enzyme have been considered. Intrinsic and extrinsic stabilizing mechanisms are two governing principles for enhanced thermal stability of enzyme in molecular basis. Factors contributing to the former and the latter mechanisms may be involved in the enhanced thermal stability of enzyme complementarily. Also, the methods for improving thermal stability of enzyme which comprise reaction in organic solvent system, chemical modification, immobilization, sequential unfolding and refolding, gene manipulation techniques and enzyme-antibody complexing are reviewed.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2513-2516
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• 2012

This study examined the effects of the epoxidized castor oil (ECO) and $Al_2O_3$ content on the thermal stability and fracture toughness of the diglycidylether of bisphenol-A (DGEBA)/ECO/$Al_2O_3$ ternary composites using a range of techniques. The thermal stability of the composites was decreased by the addition of ECO and $Al_2O_3$ nanoparticles. The fracture toughness of the composites was improved significantly by the addition of ECO and $Al_2O_3$ nanoparticles. The composite containing 3 wt % $Al_2O_3$ nanoparticles showed the maximum flexural strength. Scanning electron microscopy (SEM) revealed tortuous cracks in the DGEBA/ECO/$Al_2O_3$ composites, which prevented deformation and crack propagation.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2560-2566
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• 2012

The present study investigates how the thermal stability of retinol (vitamin A) encapsulated in polyester nanoparticles is influenced by the types of polyester used for the nanoparticles. A variety of polyester-retinol nanoparticles were prepared with various polyesters like: poly(ethylene adipate), PEA; poly(butylene adipate), PBA; poly(hexamethylene adipate), PHMA; and three polycaprolactones, PCL, of different molecular weights ($M_n$ ~10, 40, and 80K). The chemical stability of retinol in these nanoparticles, monitored in an aqueous solution at $25^{\circ}C$ and $40^{\circ}C$ for 4 weeks, was high in the following order of the nanoparticles prepared with PHMA > PCL 40K > PCL 10K > PCL 80K > PBA~PEA at $25^{\circ}C$ and PCL 10K > PCL 40K > PHMA > PCL 80K > PEA > PBA at $40^{\circ}C$. More importantly, this study has also found that the thermal stability of the retinol in the nanoparticles was closely connected with the melting temperatures of polyesters and polyester nanoparticles. The results were further discussed with possible factors - such as sample preparation condition (or history) and miscibility between the polyesters and retinol - affecting $T_m$ of the polyesters and the nanoparticles.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.145-148
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• 2011

The thermal behavior of lithiated Si anodes has been investigated using differential scanning calorimetry (DSC). In particular, the effect of Si particle size on the thermal stability of a fully lithiated Si electrode was investigated. For DSC measurements, a lithiated Si anode was heated in a hermetically sealed high-pressure pan with a polyvinylidene fluoride (PVDF) binder and a 1 M $LiPF_6$ solution in an ethylene carbonate (EC)-diethyl carbonate (DEC) mixture. The thermal evolution around $140^{\circ}C$ increases with lithiation and with decreasing particle size; this phenomenon is attributed to the thermal decomposition of the solid electrolyte interface (SEI) film. Exothermic peaks, following a broad peak at around $140^{\circ}C$, shift to a lower temperature with a decrease in particle size, indicating that the thermal stability of the lithiated Si electrode strongly depends on the Si particle size.

• Elastomers and Composites
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• 제58권2호
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• pp.70-80
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• 2023

The effect of phenylphosphonic acid (PPOA) on polyurethane (PU) thermal stability was studied through Fourier transform infrared spectroscopy and Thermogravimetric analysis. To synthesize PPOA-modified PUs (PPOA-PUs), polyether-type diols (Mw=62, 106, 190, 419, 605) were chemically modified with PPOA and then reacted with 4,4'-dicyclohexylmethane diisocyanate (H₁₂MDI) and 4,4-diphenylmethane diisocyanate (MDI). During thermal decomposition in air, the PPOA embedded in the PUs formed intumescent phosphocarbonaceous char. Below 400℃, PPOA-H₁₂MDI-PUs were more unstable, as PPOA decomposed at lower temperatures than phenyl groups and aliphatic ethers. Above 550℃, the thermal stability of PUs followed this order: PPOA-MDI-PUs > PPOA-H₁₂MDI-PUs > MDI-PUs > H₁₂MDI-PUs. At 700℃, unmodified PUs had no residue, while the PPOA-MDI-PU residue was 4.4~23.0 wt.% and the PPOA-H₁₂MDI-PU residue was 1.5~17.5 wt.%. The enhanced thermal stability of PPOA-MDI-PUs at high temperatures can be attributed to the synergetic effect of PPOA and phenyl groups on the formation of phosphocarbonaceous char.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.130-134
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• 2002

Polyol esters were synthesized by condensation reaction of polyols (PE and DIPE) and linear acids such as valeric acid, caproic acid, heptylic acid and caprylic acid. The structures of polyol esters were confirmed by gas chromatography. Hot tube test was used to measure thermal stability of polyol esters and its thermal properties depended on the structure of acid moiety contained in polyol esters.

• Tribology and Lubricants
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• 제18권5호
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• pp.319-323
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• 2002

Polyol esters were synthesized by condensation reaction of polyols (PE and DiPE) and linear acids such as valeric acid, caproic acid, heptylic acid and caprylic acid. The structures of polyol esters were confirmed by gas chromatography. Hot tube test was used test was used to measure thermal stability of polyol esters and its thermal properties depended on the structure of acid moiety contained in polyol esters.