• Korean Journal of Materials Research
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• v.11 no.9
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• pp.786-791
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• 2001

$\alpha$,$\omega$-Bis(4-glycidyloxybenzylidene-4-aminophenyl)methane (BGBAM) was synthesized from the initial materials, 4-hydroxylbenzaldehyde (HBA), 4,4'-methylenedianiline (MDA) and epichlorohydrin. The DSC trace for BGBAM shows two endotherms associated with the liquid crystalline phase transition around $104.2^{\circ}C$ and the isotropic transition around $171.2^{\circ}C$, and it also has a broad exotherm in the range of $178~300^{\circ}C$ due to the anionic homopolymerization of BGBAM. DSC curve for the curing of BGBAM with hexamethylene diamine (HMD) shows an endothermic peak around $93^{\circ}C$ attributed to the melting of BGBAM. It also has three exothermic peaks around $128.4^{\circ}C$ and $180.2^{\circ}C$ associated with the epoxide-amine reaction and weak peak in the range of $200~263^{\circ}C$ related to the anionic homopolymerization between the unreacted epoxide groups. The activation energy values of cure reaction by Kissinger method are 66.5, 67.3 and 90.6 kJ/mol for $T_{pl},\; T_{p2}\; and \;T_{p3},\; respectively$. The kinetic parameters by isoconverional method are similar value to those from Kissinger method.

• Journal of the Korean Chemical Society
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• v.57 no.1
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• pp.109-114
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• 2013

The effects of aluminum nanoparticles (AlNs) on the thermal decomposition of ammonia perchlorate (AP) were investigated by DSC, TG-DSC and DSC-TG-MS-FTIR. Addition of AlNs resulted in an increase in the temperature of the first exothermic peak of AP and a decrease in the second. The processing of non-isothermal data at various heating rates with and without AlNs was performed using Netzsch Thermokinetics. The dependence of the activation energy calculated by Friedman's isoconversional method on the conversion degree indicated the decomposition process can be divided into three steps. They were C1/D1/D1 for neat AP, determined by Multivariate Non-linear Regression, and changed to C1/D1/F2 after addition of AlNs into AP. The isothermal curves showed that the thermal stability of AP in the low temperature stage was improved in the presence of AlNs.

• Journal of the Korean Wood Science and Technology
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• v.40 no.2
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• pp.110-122
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• 2012

This study investigated the effects of layered clay on the thermal curing behavior and tensile properties of resole phenol-formaldehyde (PF) resin/clay/cellulose nanocomposites. The thermal curing behavior of the nanocomposite was characterized using conventional differential scanning calorimetry (DSC) and temperature modulated (TMDSC). The addition of clay was found to accelerate resin curing, as measured by peak temperature ($T_p$) and heat of reaction (${\Delta}H$) of the nanocomposite’ curing reaction increasing clay addition decreased $T_p$ with a minimum at 3~5% clay. However, the reversing heat flow and heat capacity showed that the clay addition up to 3% delayed the vitrification process of the resole PF resin in the nanocomposite, indicating an inhibition effect of the clay on curing in the later stages of the reaction. Three different methods were employed to determineactivation energies for the curing reaction of the nanocomposite. Both the Ozawa and Kissinger methods showed the lowest activation energy (E) at 3% clay content. Using the isoconversional method, the activation energy ($E_{\alpha}$) as a function of the degree of conversion was measured and showed that as the degree of cure increased, the $E_{\alpha}$ showed a gradual decrease, and gave the lowest value at 3% nanoclay. The addition of clay improved the tensile strengths of the nanocomposites, although a slight decrease in the elongation at break was observed as the clay content increased. These results demonstrated that the addition of clay to resole PF resins accelerate the curing behavior of the nanocomposites with an optimum level of 3% clay based on the balance between the cure kinetics and tensile properties.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.3
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• pp.418-424
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• 2015

The chemical response of energetic materials is analyzed in terms of 1) the thermal decomposition under the thermal stimulus and 2) the reactive flow upon the mechanical impact, both of which give rise to an exothermic thermal runaway or an explosion. The present study aims at building a set of chemical kinetics that can precisely model both thermal and impact initiation of a heavily aluminized cyclotrimethylene-trinitramine (RDX) which contains 35% of aluminum. For a thermal decomposition model, the differential scanning calorimetry (DSC) measurement is used together with the Friedman isoconversional method for defining the frequency factor and activation energy in the form of Arrhenius rate law that are extracted from the evolution of product mass fraction. As for modelling the impact response, a series of unconfined rate stick data are used to construct the size effect curve which represents the relationship between detonation velocity and inverse radius of the sample. For validation of the modeled results, a cook-off test and a pressure chamber test are used to compare the predicted chemical response of the aluminized RDX that is either thermally or mechanically loaded.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.547-553
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• 2017

Thermal analysis of three energetic materials used in pyroelectric device was performed using Differential Scanning Calorimetry (DSC). The theoretical method for extracting the reaction rate equation of energetic materials using DSC experimental data is proposed and the reaction rate extraction is performed. The results of the DSC were analyzed by the conversion method such as Friedman. Activation energy and frequency factor according to mass fraction were extracted to complete the reaction rate equation. The extracted reaction rate equation has a form that represents the entire chemical reaction process, not the assumption that the chemical reaction process of the high energy material is a main step in several stages. It has considerable advantages in terms of theoretical and accuracy as compared with the chemical reaction rate form extracted through conventional thermal analysis experiments. Using the derived reaction rate equation, we predicted the performance change of three energetic materials operating on actual storage condition over 20 years.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.79-92
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• 2019

Titanium hydride potassium perchlorate (THPP) is one of the commonly utilized pyrotechnic materials in aerospace industries. The current study elucidates the effects of hygrothermal aging on the combustion of THPP experimentally. First, applying the Differential Scanning Calorimetry (DSC) and isocoversional method, both the delay of reaction start and decrease in maximum reaction rate were observed. The kinetics parameters tended to fluctuate depending the thermal reaction or intermediate product formation of THPP. Also, the oxidants decomposition and fuel oxidation phenomenon were discovered by X-ray photoelectron spectroscopy (XPS). The experimental heat from DSC data were verified as reasonable by comparing with the theoretical heat obtained utilizing both THPP formulation from XPS and NASA Chemical Equilibrium with Applications (CEA). Both data had identical variation trend, which expecially had the highest heat value at 10 weeks aged sample.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.145-153
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• 2015

$Cr_2O_3/AP$ (ammonium perchlorate) energetic composites were prepared by a method of solvent/anti-solvent. XRD analysis revealed that the crystalline structure of AP in $Cr_2O_3/AP$ composites is the same as that of pure AP. SEM photomicrograph shows that an average size of cuboid $Cr_2O_3/AP$ composites is approximately $2.5{\mu}m$. TGA analysis shows that the addition of submicron $Cr_2O_3$ particles into AP lowers the HTD (high-temperature decomposition) compared to that of neat AP and the activation energy of the $Cr_2O_3/AP$ composites was calculated by the isoconversional Starlink method. Considering changes in the activation energy, the decomposition reaction mechanism of AP was suggested as follows; the decomposition with the formation of nucleation sites renders formation of porous structure in the composites up to conversion of about 0.25 and after further conversion of over 0.3, it seems that decomposition reaction vigorously takes place rather than sublimation of AP.