• Elastomers and Composites
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• v.42 no.1
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• pp.55-58
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• 2007

Thermal Characterization of an EPDM/IIR rubber blend was performed using TG/DTG analysis. While TGA thermograms of a virgin EPDM and IIR showed their own characteristic thermal decomposition curves, that of an EPDM/IIR blend sample showed a characteristic curve, exhibiting both decomposition characteristics of EPDM and IIR. This finding was more clarified from DTG analysis obtained by differentiation of TGA thermograms, being exhibited as two distinct shifted-peaks. Degrees of peak-shift (${\Delta}T$) compared to their original positions were $+25\;^{\circ}C$ for IIR and $-15\;^{\circ}C$ for EPDM, respectively. From these facts, thermal stability of EPDM is considered comparatively better than IIR, and moreover, it can be an evidence for the characteristics of a partial compatibility between EPDM and IIR. It is noteworthy that, if we prepare in advance a calibration curve for the composition about EPDM/IIR blend, it may be possible to analyze quantitatively an EPDM/IIR blend, using comparatively simple TGA experiments as in the present work.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.8-16
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• 2024

Limestone (CaCO₃, calcium carbonate), which is used as a raw material in the portland cement and steel industry, emits CO₂ through decarbonation by high temperatures in the manufacturing process. To reduce CO₂ emissions by the use of raw materials like limestone, it has been proposed to replace limestone with various industrial by-products that contain CaO but less or none of the carbonated minerals, that cause CO₂ emissions. Loss of Ignition (LOI), Thermogravimetric analysis (TG), and Infrared Spectroscopy (IR) are used to quantitative the amount of CO₂ emission by using these industrial by-products, but CO₂ emissions can be either over or underestimated depending on the characteristics of by-product materials. In this study, we estimated CO₂ contents by LOI, TG, IR and DTG(Differential Thermogravimetric analysis) of calcite(CaCO₃) and samples that contain CO₂ in the form of carbonate and whose weight increases by oxidation at high temperatures. The test results showed for CaCO₃ samples, all test methods have a sufficient level of reliability. On the other hand, for the CO₂ content of the sample whose weight increases at high temperature, LOI and TG did not properly estimate the CO₂ content of the sample, and IR tended to overestimate compared to the predicted value, but the estimated result by DTG was close to the predicted valu e. From these resu lts, in the case of samples that contain less than a few percent of CO₂ and whose weight increases during the temperature that carbonate minerals decompose, estimating the CO₂ content using DTG is a more reasonable way than LOI, TG, and IR.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.341-345
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• 2011

The Schiff base cobalt(II) complex, bis[4-chloro-2-((E)-(isopropylimino) methyl) phenol]cobalt(II), has been prepared and characterized by single-crystal X-ray diffraction analyses. The phenomenological, kinetic and mechanistic aspects of the cobalt (II) complex have been studied by TG/DTG techniques. On the basis of the experimental data, the kinetic parameters such as activation energy, pre-exponential factor and entropy of activation were computed, and then the most probable mechanism function was estimated as $g({\alpha})={\alpha}^2$ 2. Hence the rate controlling process at all stages of decomposition is onedimensional diffusion (Parabolic model).

• Journal of Microbiology and Biotechnology
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• v.20 no.6
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• pp.1032-1041
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• 2010

The comparative influence of two nanoparticles [viz., superparamagnetic iron oxide nanoparticles (SPION) and nanobarium titanate (NBT)] upon the in vitro and in situ low-density polyethylene (LDPE) biodegradation efficiency of a potential polymer-degrading microbial consortium was studied. Supplementation of 0.01% concentration (w/v) of the nanoparticles in minimal broth significantly increased the bacterial growth, along with early onset of the exponential phase. Under in vitro conditions, ${\lambda}$-max shifts were quicker with nanoparticles and Fourier transform infrared spectroscopy (FTIR) illustrated significant changes in CH/$CH_2$ vibrations, along with introduction of hydroxyl residues in the polymer backbone. Moreover, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) reported multiple-step decomposition of LDPE degraded in the presence of nanoparticles. These findings were supported by scanning electron micrographs (SEM), which revealed greater dissolution of the film surface in the presence of nanoparticles. Furthermore, progressive degradation of the film was greatly enhanced when it was incubated under soil conditions for 3 months with the nanoparticles. The study highlights the significance of bacteria-nanoparticle interactions, which can dramatically influence key metabolic processes like biodegradation. The authors also propose the exploration of nanoparticles to influence various other microbial processes for commercial viabilities.

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.908-916
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• 2010

Fullerene-60 nanoparticles were used for studying their effect on the low-density polyethylene (LDPE) biodegradation efficiency of two potential polymer-degrading consortia comprising three bacterial strains each. At a concentration of 0.01% (w/v) in minimal broth lacking dextrose, fullerene did not have any negative influence upon the consortia growth. However, fullerene was found to be detrimental for bacterial growth at higher concentrations (viz., 0.25%, 0.5%, and 1%). Although addition of 0.01% fullerene into the biodegradation assays containing 5mg/ml LDPE subsided growth curves significantly, subsequent analysis of the degraded products revealed an enhanced biodegradation. Fourier transform infrared spectroscopy (FT-IR) revealed breakage and formation of chemical bonds along with the introduction of ${\nu}C$-O frequencies into the hydrocarbon backbone of LDPE. Moreover, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) revealed a higher number of decomposition steps along with a 1,000-fold decrease in the heat of reactions (${\Delta}H$) in fullerene-assisted biodegraded LDPE, suggesting the probable formation of multiple macromolecular byproducts. This is the first report whereby fullerene-60, which is otherwise considered toxic, has helped to accelerate the polymer biodegradation process of bacterial consortia.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1481-1486
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• 2013

Bifunctional Fe-SBA-15-$SO_3H$ mesoporous materials with different Si/Fe molar ratios (3, 5, and 7) have been synthesized via a simple direct hydrothermal method and characterized by XRD, $N_2$-adsorption/desorption, TG/DTG and FT-IR techniques, and used as solid acid catalysts in the esterification of lactic acid with methanol. XRD and $N_2$ sorption characterizations show successful iron doping within the mesoporous channels of SBA-15-$SO_3H$. The FT-IR and TG/DTG characterizations also reveal the presence of iron. With the incorporation of Fe ions into the SBA-15-$SO_3H$, the acid sites substantially increased because of the self-separated acidity of the hydrolysis of $Fe^{3+}$ solutions. However, in the Si/Fe = 3 molar ratio, the catalytic conversion decreased which is caused by the reduced cooperation effect between the acid pairs due to the weakened hydrogen bonds and collapse of the pore structure. This further suggests that the mesoporous structure decreases with the decrease in Si/Fe ratio.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.746-754
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• 2019

Vitrification of radioactive liquid waste (RLW) provides a feasible solution for isolating radionuclides from the biosphere for an extended period. In vitrification, base glass and radioactive waste are added simultaneously into the melter. Determination of heat and mass transfer rates is necessary for rational design and sizing of melter. For obtaining an assured product quality, knowledge of reaction kinetics associated with the thermal decomposition of waste constituents is essential. In this study Thermogravimetry (TG) - Differential Thermogravimetry (DTG) of eight kinds of nitrates and two oxides, which are major components of RLW, is investigated in the temperature range of 298-1273 K in the presence of base glasses of five component (5C) and seven component (7C). Studies on thermal behavior of constituents in RLW were carried out at heating rates ranging from 10 to $40\;K\;min^{-1}$ using TG - DTG. Thermal behavior and related kinetic parameters of waste constituents, in the presence of 5C and 7C base glass compositions were also investigated. The activation energy, pre-exponential factor and order of the reaction for the thermal decomposition of 24% waste oxide loaded glasses were estimated using Kissinger method.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.34-41
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• 2002

This study investigated the thermogravimetric analysis of two types of cured tannin-based adhesives from wattle and pine, with three hardeners of paraformaldehyde, hexamethylenetetramine and TN (tris(hydroxyl)nitromethan), at a temperature of 170℃ and a heating rate of 5, 10, 20 and 40℃/min for 10 minutes. The 5 minutes cured wattle tannin-based adhesive with each hardener at 170℃ was also tested to compare the degree of curing. It was found that thermogravimetric analysis could be used to measure the degree of curing of a thermosetting adhesive. The TG-DTG curves of all the adhesive systems were similar and showed three steps in a similar way to a phenolic resin. This means that each adhesive system is well cross-linked. However, a high thermal decomposition rate was shown at 150 to 400℃ in the case of the pine tannin sample with TN (tris(hydroxyl)nitromethan). The Flynn & Wall expression was used to evaluate the activation energy for thermal decomposition. As the level of conversion (𝛼) increased, the activation energy of each system increased. The activation energy of the wattle tannin-based adhesive with paraformaldehyde was higher than the others.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.31-42
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• 2007

To investigate the pyrolytic and anatomical characteristics of Korean softwood, Pinus densi-flora, Pinus rigida and Larix leptolepis, and hardwood, Acer palntatum, Fraxinus rhynchophylla and Quercus variabilis, chemical components analysis, TG-DTA (Thermogravimetric Analysis & Differential Thermal Analysis), MBA (Methylene Blue Adsorption) test and SEM observation were carried out. For TG-DTA, samples were carbonized up to $800^{\circ}C$ at the heating rate of $10^{\circ}C$/min under $N_2$ flows 1 l/min using thermogravimetric analyzer. Chemical component analysis of all samples resulted in typical contents of major wood component. In TG-DTA results, softwood showed higher char yield than hardwood, and lignin displayed the highest char yield among the major wood components. All samples showed typical TGA, DTG and DTA curves for wood pyrolysis except a few differences between softwood and hardwood. Content of lignin influenced its pyrolysis characteristics, while molecular structure of lignin affected not only the weight loss but also the yield of char. In MBA test results, MBA of softwoods was higher than that of hardwoods. Char of Pinus densiflora showed the highest MBA, but its degree was lower than activated carbon or fine charcoal about 23 and 4 times, respectively. SEM observation showed carbonization process preserves wood structure and retain the micro-structure of wood fibers.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.706-710
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• 2021

In the current research, thermal and catalytic thermogravimetric (TG) analysis of polyethylene terephthalate (PET) over natural zeolite (NZ), olivine, bentonite, HZSM-5, and HAl-MCM-41 were investigated using a TG analyzer and model-free kinetic analysis. Catalytic TG analysis of PET was carried out at multi-heating rates, 10, 20, 30, and 40 ℃/min, under nitrogen atmosphere. Apparent activation energy (Ea) values for the thermal and catalytic pyrolysis of PET were calculated using Flynn-Wall-Ozawa method. Although natural catalysts, NZ, olivine, and bentonite, could not lead the higher PET decomposition efficiency than synthetic zeolites, HZSM-5 and HAl-MCM-41, maximum decomposition temperatures on the differential TG (DTG) curves for the catalytic pyrolysis of PET, 436 ℃ over olivine, 435 ℃ over bentonite, and 434 ℃ over NZ, at 10 ℃/min, were definitely lower than non-catalytic pyrolysis. Calculated Ea values for the catalytic pyrolysis of PET over natural catalysts, 177 kJ/mol over olivine, 168 kJ/mol over bentonite, and 171 kJ/mol over NZ, were also not lower than those over synthetic zeolites, however, those were also much lower than the thermal decomposition, suggesting their feasibility as the proper and cost-effective catalysts on the pyrolysis of PET.