• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.30-33
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• 1994

This paper studies on the effect of DSC(Differential Scanning Calorimeter) analysis condition on the glass transition temperature of silica filled epoxy network polymer used for ultra-high voltage apparatus. The effects of temperature scanning rate specimen size and gas flow rate on measured glass transition temperature have been studied in order to select optimum thermal analysis condition.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.75-79
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• 2001

For handling and storage of reactive chemicals, the hazard evaluations have been extremely important. In the chemical industry, the most concerns are focused on the thermal harzards such as runaway reactions and thermal decompositions, which are mostly governed by thermodynamics and reaction kinetics or these reactive chemical in the system. This study no investigated the thermal decomposition characteristics of nitrophenylhydrazine isomers by using differential scanning calorimeter(DSC) and accelerating rate calorimeter(ARC). Experimental results showed that exothermic onset-temperatures in nitrophenylhydrazine(NPH) isomers were about 160-$210^{\circ}C$ by DSC and 100-$150^{\circ}C$ by ARC. The decomposition temperature acquired by ARC was about 50-$60^{\circ}C$ lower than that by DSC. Reaction heats were about 40-100cal/g by DSC and 330-750ca1/g by ARC. While ortho isomer of NPH show two distinct exothermic peaks, para isomer shows a single peak in DSC curves. The first exothermic peak for 2-NPH is mainly due to intramolecular dehydration forming 1-hydroxybenzotriazole(HOBT) and the second exothermic peak is mainly due to the decomposition of HOBT formed in the first step of decomposition. The exothermin peak in the DSC curve for 4-NPH is mainly due to dissociation of hydrazino and nitro groups.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.976-981
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• 2012

In this study, hardness, microstructure and temperature of glass transition are measured respectively by using SEM (Scanning electron microscope) and DSC (Differential scanning calorimeter) to analyze the effects on material properties by after-curing in the epoxy resin. As the result of hardness test according to the after-curing conditions, the higher the temperature of after-curing, hardness and heat resistance are, the higher hardness is. As a result of microstructure for each specimen by SEM, it could be confirmed that the specimen with after-curing has more dense fracture surface. It is also found that temperatures of glass transitions by DSC are comparatively higher in the specimens with after-curing, and the differences between after-curing conditions are negligible.

• Elastomers and Composites
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• v.48 no.4
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• pp.276-281
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• 2013

Polyester type polyurethane foam modified with acrylic polyol was prepared by quasi prepolymer method. Thermal and dynamic mechanical properties of polyurethane foam were analysed by thermal gravimetric analysis(TGA) and dynamic mechanical analysis(DMA). Also, glass transition temperature was measured by differential scanning calorimeter(DSC). As acrylic polyol contents were increased, thermal stability measured by TGA was slightly decreased. Storage modulus was increased and tan delta was decreased with increasing of acrylic polyol contents.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.59-65
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• 2018

We conducted an isothermal slow cook-off(ISCO) test for an aluminized explosive containing AP. The sample bulged before the run-away reaction, and therefore we were unable to obtain the ISCO data. However, these phenomena did not occur for a certain AP grade, which means that the quality of the AP exerted a significant effect on the thermal stability of the explosive formulation. In this study, we investigated the thermal stability difference between a good and bad AP grade. First, we characterized the thermal properties of all APs by Differential Scanning Calorimeter(DSC) and correlated them to the ISCO phenomena. In addition to the DSC study and ISCO test, we also investigated and calculated the SADT and self-heating rate by the ARC of the different AP qualities to interpret the thermal stability of the explosive formulation. Moreover, we investigated the impurity of the AP and a preparation method to remove the included impurity and crystallization. Finally, we implemented qualification methods to identify the quality of AP by DSC using a high-pressure crucible.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.61-65
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• 2010

Most of the chemical reactions performed in the chemical industry are exothermic, meaning that thermal energy is released during the reaction. It is also important to understand the thermal hazards such as thermal stabilities and runaway reactions, which are governed by thermodynamics and reaction kinetics of the mixed materials. The paper was described the evaluation of thermal behavior caused by an exothermic batch process in manufacture of the vinyl acetate resin. The aim of the study was to evaluate the thermal stabilities of raw materials with operating conditions such as a reaction inhibitor, heating rate, reaction atmosphere and the mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed in the differential scanning calorimeter(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). It was suggested that we should provide the thermal characteristics for raw materials to present safe precautions with operating conditions in the vinyl acetate polymerization process.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.180-185
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• 1998

The evaluation of thermal and pressure hazard of chemicals on the manufacturing, transporting and storaging is important in the chemical industry for safety. In this study, the thermal decomposition characteristics of intermediate of Saccharin were investigated by using Accelerating Rate Calorimeter(ARC) and Differential Scanning Calorimeter(DSC). Experimental results showed that decomposition temperatures in p-TSA were about 280~$318^{\circ}C$ by DSC and $201^{\circ}C$ by ARC. In case of o-TSA were about $336^{\circ}C$~$360.8^{\circ}C$ by DSC and $299^{\circ}C$ by ARC. The decomposition temperature acquired by ARC was about $70^{\circ}C$ lower than that by DSC. The exothermic runaway reaction in case of p-TSA occured in 598 minute and o-TSA in 5 minute. For the safety in the chemical industry, we should consider the ARC data as well as DSC data in the handling and design of process.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.740-745
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• 2011

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when an electrical current is passed throught. In this study, we observed the physical & chemical characteristics changes which occurs in soybean protein during heating denaturation by using ohmic and conventional heating. After the ohmic heating process, we could not find any change of the primary protein structure in the denaturated soy protein samples. However, the rate of imbibed water(RIW) of the ohmic samples was 2 times faster than that of the conventional samples. Also the ANS-surface hydrophobicity was decreased, which is very closely related to RIW. In the differential scanning calorimeter(DSC) analysis result, all 7S soyprotein fraction samples were completely denaturated by ohmic and conventional heating. However, the 11S samples were completely denatured only by ohmic heating. According to the DSC result, we decided that soyprotein was damaged by temperature and electrical current during ohmic heating. The damage of electrical current was a cause of the characteristic changes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.513-516
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• 2017

When stored for long periods in a powder-based device (PMD), the explosive power in the device is aged and the explosive power is changed. Thus, The gunpowder used in the PMD must be chemically and physically stable for both internal and external factors. Since $BKNO_3$ and THPP are used as representative gunpowder, thermodynamic and kinetic analyzes were performed based on these gunpowders. Differential scanning calorimeter (DSC) was used to analyze the calorific value and reaction rate. As a result, there was no significant change in caloric value and reaction rate in THPP. In addition, XPS and TEM-EDS analyzes were performed to confirm the formation of oxide films directly related to aging, and no oxide films were observed as a result of thermal analysis. In addition, XPS and TEM-EDS analyzes were performed to confirm the formation of oxide films directly related to aging. As a results, no oxide films were observed. It can be concluded that THPP is the most famous gunpowder in terms of long-term stability.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.111-118
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• 1992

The curing acceleration of epoxy/amine system was investigated by using differential scanning calorimeter(DSC), The epoxy, diglycidylether of bisphenol A (DGEBA) was cured with methylene dianiline (MDA) with or without accelerators. Two kinds of accelerators were tested for the study ; tris(dimethylaminomethyl)phenol (DMP - 30) and 3 - (3,4 - dichlorophenyl)-1, 1-dimethylurea (DIURON). Heats of reaction and glass transition temperatures ($T_g$) of the cured epoxy system were analyzed by DSC along with the estimation of activation energy by the dynamic DSC studies. It was found that DMP - 30 is more effective accelerator than DIURON which showed faster curing and lower activation energy.