• Fire Science and Engineering
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• v.13 no.2
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• pp.26-32
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• 1999

We had investigated combustion pro야$\pi$ies of rice bran dusts. Decomposition of rice bran d dusts with temperature were investigated using DSC and the weight loss according to t temperature using TGA in order to find the thermal hazard of rice bran dusts, and the p properties of dust explosion in variation of their dust with the same particle size. Using H Hartman's dust explosion apparatus which estimate dust explosion by electric ignition after m making dust disperse by compressed air, dust explosion experiments have been conducted by v varying concen$\sigma$ation and size of rice br뻐 dust. According to the results for thermodynamic stability of rice bran dust, there are little change of initiation temperature of heat generation 때d heating value for used particle size. But i initiation temperature of heat generation decreased with high heating rate whereas d decomposition heat increased with particle size. Also, the explosion pressure was increased as t the ignition energy increased and average maximum explosion pressure was 13.5 kgv'cnt for 5 BJ/60 mesh and 1.5 뼈Ie미 dust concentration.

• Polymer(Korea)
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• v.38 no.3
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• pp.314-319
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• 2014

Three kinds of thermal stabilizers for nylon 4 were synthesized to incorporate both hindered amine groups and methylene units with various lengths. It is expected that the hindered amine groups play a role in the capture of degradation-triggering species. Considering sequence rules, hydrogen bonding formed between nylon 4 and the stabilizers is optimized to alter the lengths of the methylene units in the stabilizers. As a result, it was found that a tetramethylene unit in the stabilizer is an optimal length for hydrogen bonding in terms of isothermal thermogravimetric analysis (TGA). Considering the slight and often negligible improvement of thermal stability of nylon 4 containing commercially-available nylon 6 stabilizers, retardation of thermal degradation has been substantially improved upon.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1661-1667
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• 2009

Post-cure characteristics of a silicone rubber material which is widely used for a LCD lamp holder were investigated using thermogravimetric analysis (TGA). Research was especially focussed on searching for the optimum post-cure conditions in relation to the practical operation environments. The results showed that incipient volatile temperature(Ti) during the process was considered as the most important factor and, thereby, post-curing for 2hrs at $250^{\circ}C$seemed to be a reasonable condition in the practical view-point. Arrhenius plot of shift factors which were empirically determined from the time-temperature-superposition-principle showed good linearity, exhibiting the post-cure mechanism might be proceeded through single mechanism with activation energy of 108.25kJ/mol.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1027-1034
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• 2010

Effects of inorganic nano-powders on the polymerization and thermal degradation kinetics as well as the mechanical properties of polyurethane nano-composites were studied by both the measurement of polymerization temperature as a function of time and non-isothermal thermogravimetric analysis (TGA) as well as the Instron test. As the results from polymerization studies, the reaction rates of MMT-filled PU composites were faster than those of Ce500-filled ones, and moreover, the activation energies using Kissinger method for the thermal degradation of composites were calculated as 139.34 kJ/mol for the Ce500-filled PU composites and 91.12 kJ/mol for MMT-filled one, respectivel, exhibiting that MMT nano-powder seemed to be acting as the catalyst for both polymerization and degradation of PU composites. UTM result, however, showed that tensile strength at break of MMT-filled composites was much higher than that of Ce500-filled ones above the concentrations range of 5 phr in the composites.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.636-641
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• 2011

Since the mid-1990s, the number of fires continue to increase and the size has been also larger. However, the pyrolysis and combustion characteristics of the various species of the medium such as fallen leaves, herbaceous plants, conifers and broadleaf trees have scarcely been studied. In this paper, we investigate the pyrolysis and combustion of the typical domestic needle-leaf tree of Pinus densiflora and thinning-out tree by thermogravimetric analysis (TGA). Pinus densiflora was ignited at $200^{\circ}C$ and pyrolysis from $230^{\circ}C$. In case of thinning-out tree was ignited and pyrolysis at $180^{\circ}C$ and $205^{\circ}C$, respectively. The values of activation energy for pyrolysis were increased as the conversion efficiency increasing from 10% to 80%, whereas the values was decreased during combustion.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.4
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• pp.207-212
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• 2009

In this study, a thermal behavior of $PrCl_3$ as one of the lanthanide chlorides in LiCl-KCl molten salts was investigated in an oxidizing condition. First, a thermo-gravimetric analysis (TGA) of $PrCl_3$ was carried out by an injection of $O_2$ gas. Based on the results, an oxidation of $PrCl_3$ in the molten salts was performed by sparging $O_2$ gas with changing temperatures. According to the TGA data of $PrCl_3$, a dissociation of $PrCl_3$ occurred rapidly by about $380^{\circ}C$ and a conversion of $PrCl_3$ to $PrCl_3$ was completed at about $600^{\circ}C$. The thermal behavior of $PrCl_3$ in LiCl-KCl molten salts by sparging $O_2$ gas was similar to that of $PrCl_3$ in the TGA test, and PrOCl as a insoluble compound in the molten salts was precipitated into the bottom of the molten salts. A conversion of $PrCl_3$ to PrOCl in the molten salts occurred actively at a higher temperature than $650^{\circ}C$. And it would be possible to estimate a conversion status of $PrCl_3$ to PrOCl by measuring a $Cl_2$ concentration in a flue gas generated from an oxidation test of $PrCl_3$ in LiCl-KCl molten salts.

• Journal of the Korean Electrochemical Society
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• v.16 no.1
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• pp.52-58
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• 2013

In order to overcome the cost issue for commercialization of polymer electrolyte membrane fuel cell (PEMFC), this research was conducted for replacing platinum cathode catalyst with non-precious metal catalyst. The non-precious metal catalyst (Co-PANI-C) was synthesized by the simple reduction method with polyaniline (PANI), carbon black, and cobalt precursor without any heat treatment. Characterization of new Co-PANI-C composite catalysts was done by the measurement of X-ray diffraction (XRD) and thermogravimetric analysis (TGA) for structure analysis and performed by rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) for electrochemical analysis. As a result, Co-PANI-C catalyst showed 60 mV lower on-set potential for oxygen reduction reaction (ORR) than Pt/C catalyst, but the overall reduction current of Co-PANI-C catalysts by ORR was still smaller than that of Pt/C. In addition, the ORR behavior of Co-PANI-C catalysts depending on the rotation speed of electrode and the stability of Co-PANI-C catalyst under potential cycling and the performance of fuel cell conditions are also discussed.

• Polymer(Korea)
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• v.37 no.3
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• pp.308-315
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• 2013

In this study, we performed surface modification of silica nanoparticles with bis[3-(triethoxysilylpropyl)]tetrasulfide (TESPT) silane coupling agent to study the effects of treatment temperature, treatment time, and amount of TESPT used on the silanization degree with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), elemental analysis (EA) and solid state $^{13}C$ and $^{29}Si$ cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR). We found peak area of isolated silanol groups at $3747cm^{-1}$ decreased, but peak area of $-CH_2$ asymmetric stretching of TESPT at $2938cm^{-1}$ increased with the amount of TESPT from FTIR measurements. We also used universal testing machine (UTM) to study mechanical properties of styrene butadiene rubber (SBR) nanocomposites with 20 phr (parts per hundred of rubber) of pristine and TESPT modified silicas, respectively. The tensile strength and 100% modulus of modified silica/SBR nanocomposite were enhanced from 5.65 to 9.38MPa, from 1.62 to 2.73 MPa, respectively, compared to those of pristine silica/SBR nanocomposite.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.60-67
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• 2017

In this study, we performed surface modification of biodegradable microcrystalline cellulose (MCC) to use as a filler in polyethylene (PE) composite in food packaging application. We modified MCC surface with (3-trimethoxysilylpropyl)diethylenetriamine (TPDT) silane coupling agent, which has one primary amino group and two secondary amino groups per molecule, to introduce amino groups with a carbon dioxide adsorption capability in MCC. Effects of each of the reaction conditions such as amount of TPDT introduced, swelling time, reaction temperature, and reaction time on surface modification degree of MCC were investigated by changing a variety of above reaction conditions. The amount of TPDT grafted on MCC surface and formation of chemical bonds were confirmed by Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and solid state $^{29}Si$ nuclear magnetic resonance (NMR) spectroscopy. We confirmed increase of grafted amount of TPDT on MCC with increasing reaction time, reaction temperature, and amount of introduced TPDT.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.133-137
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• 2001

In this research, we synthesized various photo-crosslinkable polyimide based polymers. The control of pretilt angles for a nematic liquid crystal (NLC) using the photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimetric analysis (TGA) measurement until 450C. High pretilt angles of the NLC were otained by polarized UV exposure on the photopolymers containing biphenyl (BP), decyl (de), and cholesteryl (chal) groups, respectively. However, low pretilt angles of the NLC were measured by polarized UV exposure on the photopolymers containing fluorine and chalcone groups. The high NLC pretilt angles generated are attributable to the biphenyl and alkyl moieties, and the photodimerized chalocone group of the photopolymers. Additionally, good voltage-transmittance and response time characteristics were observed by UV exposure on the photopolymers.