• Applied Chemistry for Engineering
• /
• 제23권3호
• /
• pp.352-357
• /
• 2012

Techniques of thermal analyses such as DSC and TGA have been used in the study of activation energy (Ea) and frequency factor (A) depending on the particle size of RDX and HMX. Activation energy and frequency factor were calculated by Kissinger's method and Vyazovkin's method. As the particle size of RDX increased, TGA showed activation energy increased, but DSC didn't show. However, In case of HMX, as the particle size increased, both of DSC and TGA showed increase in activation energy. Moreover, Vyazovkin's method can obtain activation energy and mechanism according to decomposition of RDX and HMX.

• Korean Chemical Engineering Research
• /
• 제47권2호
• /
• pp.169-173
• /
• 2009

Effects of variations sulfur/accelerator ratio on cross-linking and thermal degradation behavior of NR/CR rubber compounds were studied using both dynamic DSC and non-isothermal TGA. DSC thermograms of the given samples were obtained with several different heating rates, and after cross-liked in DSC, TGA thermograms with the same samples also obtained. Kissinger analysis was applied to assess the activation energies for the cross-linking and thermal decomposition processes. Results showed that the formation and thermal decomposition reaction of the samples occurred in the overall temperature range of $120{\sim}180^{\circ}C$ and $350{\sim}450^{\circ}C$, respectively, exhibiting that data could be well-fittable by Kissinger method. Furthermore, formation activation energy by DSC was estimated as $83.0{\pm}5.0kJ/mol$, which was much smaller than that of degradation by TGA, $147.0{\pm}2.0kJ/mol$. From these results, it was considered that, although variations of sulfur/accelerator ratio in the present experiments affected little on the formation mechanism and/or thermal degradation, they could play roles as the catalysts which lower the activation energy of formation. Because of stabilization after formation reaction, however, they have no more effects on the lowering the activation energy, showing higher values when decomposition, caused by main-chain scissions.

• Journal of the Korean Chemical Society
• /
• 제40권6호
• /
• pp.385-393
• /
• 1996

The interaction between poly(HEMA) which is material of contact lens containing about 45% water and amino acids (alanine, arginine, methionine, proline, glycine, serine, lysine) have been studied by using the thermal analysis methods through DSC and TGA. The experimental results of DSC and TGA were shown that lysine, arginine and alanine have the most stable interaction between poly(HEMA) and amino acids.

• International Journal of Safety
• /
• 제7권1호
• /
• pp.10-14
• /
• 2008

For evaluating the radiation degradation of cross-linked polyethylene (XLPE) cable insulation due to the irradiated oxidation, XLPE was irradiated with ${\gamma}$-ray. For each irradiated samples, TGA, DSC, FT-IR, and tensile tests were carried out. Regarding radiation degradation, oxidative process was predominant. TGA, DSC and FT-IR can be useful tools for evaluating the radiation degradation due to the irradiated oxidation because these analyses need only small amount of samples. The results of TGA, DSC and FTIR analyses showed the similar tendency for irradiated degradation. They can be useful tools for evaluating the oxidation of insulating material by non-destructive testing.

• Polymer Science and Technology
• /
• 제4권5호
• /
• pp.387-397
• /
• 1993

• YAKHAK HOEJI
• /
• 제40권3호
• /
• pp.306-310
• /
• 1996

Five pseudopolymorphic modifications of cefazolin sodium were prepared by recrystallization. They were characterized by DSC and TGA. The solubilities of all modifications were c hecked through the dissolution test.

• Elastomers and Composites
• /
• 제42권1호
• /
• pp.47-54
• /
• 2007

Reaction kinetics of polyurethane elastomers (PU) were studied using dynamic DSC and TGA for three PU samples of general purpose (Sample A), high temperature cross-likable CASE purpose with MOCA (Sample B), and RT cross-likable CASE purpose grade (Sample C). From DSC results, sample with MOCA(Sample B) showed lower shift of peak temperature, while showing broader thermograms than those of general purpose grade (Sample A). On the other hand, RT cross-linkable PU grade (Sample C) showed an interesting double mode reaction patterns, i.e., a lower temperature reaction at about $70\;^{\circ}C$, and a higher temperature reaction in the range of $140{\sim}170\;^{\circ}C$, indicating that it requires 2-step reaction process in order to complete the reaction. Once the cross-linking reaction completed, however, TGA results showed that all the samples would be considered to have similar chemical structures, showing similar decomposition processes. Sample C, especially, had showed decomposition properties of both Sample A and Sample B. Formation activation energies calculated from Kissinger method showed 10.39, 65.85, 36.52(Low $T_p$) and 18.21(High $T_p$) kcal/mol, while decomposition activation energies were 31.94, 30.84, 24.16 kcal/mol, respectively.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2007년도 제34회 KOSCO SYMPOSIUM 논문집
• /
• pp.54-59
• /
• 2007

In a view of capturing $CO_2$ as a greenhouse gas, an experimental study was conducted on the combustion characteristics of pulverized coal in $O_2$/$CO_2$ environment using TGA/DSC and DTF facilities. The effects of gas composition and concentration on the processes of devolatilization and char burning experienced by coal particles in combustion furnace and on the concentration of products such as $CO_2$, CO and $NO_x$ were observed using TGA/DSC and DTF respectively. As results, it were found that the rate of devolitilation is nearly independent on the $O_2$ concentration if it is over 20% but the char burning rate is a sensitive function of $O_2$ percent, and the two rates can be controlled by $O_2$ concentration in order to be similar with those of air combustion case. It was also found that high concentration $CO_2$ can be captured by oxy-coal combustion and high concentration of CO and low value of $NO_x$ are exhausted in that case. Additionally, NO reducing reaction by CO with char as catalyst was observed and a meaningful results were obtained.

• Journal of the Korean Applied Science and Technology
• /
• 제28권1호
• /
• pp.10-14
• /
• 2011

Emulsion polymerization was carried out using RMA like MMA, EMA, BMA and Styrene(St.) as monomer for core-shell latex preparation. It was synthesized at $80^{\circ}C$ in the presence of anionic surfactant SLS. FT-IR, TGA and DSC analysis are used to confirm synthesized core-shell emulsion latexes and to investigate the thermal characteristics of them. From analysis of TGA and DSC, the differences of the decomposition rate and the activation energy are not so large. It considers that the pendent group is not affect of the thermal characteristics and stability on core-shell latexes, which is synthesized with RMA and Styrene.

• Applied Chemistry for Engineering
• /
• 제16권2호
• /
• pp.292-295
• /
• 2005

The curing time of the phenolic resin for the processing of brake pad is very important factor for reducing the processing cost. The curing time could be investigated by examining the reaction time of the phenolic resin and hexamethylenediamine. The reaction time has been studied by FT-IR, Differential Scanning Calolimetric Analysis (DSC), and Thermogravimetric Analysis (TGA).