• Journal of the Korean Wood Science and Technology
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• 제47권4호
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• pp.486-497
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• 2019

The non-isothermal and isothermal pyrolysis properties of H lignin and P lignin extracted from different biorefinery processes (such as supercritical water hydrolysis and fast pyrolysis) were studied using thermogravimetry analysis (TGA) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). The lignins were characterized by ultimate/proximate analysis, FT-IR and GPC. Based on the thermogravimetry (TG) and derivative thermogravimetry (DTG) curves, the thermal decomposition stages were obtained and the pyrolysis products were analyzed at each thermal decomposition stage of non-isothermal pyrolysis. The isothermal pyrolysis of lignins was also carried out at 400, 500, and $600^{\circ}C$ to investigate the pyrolysis product distribution at each temperature. In non-isothermal pyrolysis, P lignin recovered from a fast pyrolysis process started to decompose and produced pyrolysis products at a lower temperature than H lignin recovered from a supercritical water hydrolysis process. In isothermal pyrolysis, guaiacyl and syringyl type were the major pyrolysis products at every temperature, while the amounts of p-hydroxyphenyl type and aromatic hydrocarbons increased with the pyrolysis temperature.

• 한국수소및신에너지학회논문집
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• 제11권1호
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• pp.11-18
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• 2000

In order to investigate the dehydriding properties of the $Mg_2NiH_x$ formed by hydrogen induced mechanical alloying, we performed isothermal thermogravimetry analysis at 453, 463, 473, 483, 493, 503 and 513K for 1 hours. Dehydrogenation kinetics were dependant strongly on the MA conditions which determine the In other words, kinds of synthesized hydrides phases and the crystal microstructures. The MA condition, 66:1 BCR(balls to chips mass ratio), especially 96h milling time, revealed the hydride phases of nano-/ amorphous state and the dehydriding activation energy of $43.4{\pm}3.6kJ/mole$.

• 한국연초학회지
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• 제5권2호
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• pp.55-62
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• 1983

Cellulose의 열분해 반응에 대한 Kinetic Parameter를 구하기 위하여 Thermogravimetry(TG)와 Differential Scanning Calorimetry(DSC)를 이용하는 네가지 비등온법을 고찰하였다. 그 결과 DSC에 의한 가열속도법과 TG에 의한 근사법이 가장 간편하였고Kinetic Parameters의 신뢰도도 매우 높았다. Cellulose 열분해 반응에서 반응차수는 1/2차였고 활성화에너지는 42kca1/mo1로 나타났다.

• Fibers and Polymers
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• 제2권2호
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• pp.75-80
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• 2001

The thermal degradation of poly(ethylene terephthalate-co-isophthalate)s (PETIs) is investigated by using isothermal thermogravimetric analysis at the temperature range of 280-31$0^{\circ}C$. The degradation rate of PETIs is increased as the mole ratio of ethylene isophthaloyl (EI) units in PETIs increases. The activation energies for the thermal degradation of poly(ethylene terephthalate), PETI(5/5), and poly(ethylene isophthalate) are 33.4, 16.6, and 8.9 kcal/mole, respectively. The degradation rate of PETIs is influenced by their volatile cyclic oligomer components formed during the polymerization and the thermal degradation. It is simulated by the rotational isomeric state model that the content of cyclic dimer in PETIs, which is the most volatile cyclic oligomer component, increases with the EI units in PETIs.

• Applied Microscopy
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• 제47권3호
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• pp.110-120
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• 2017

Non-isothermal thermogravimetry (TG) measurements on melt-quenched $Bi_xSe_{100-x}$ specimens (x=0, 2.5, 7.5 at%) were made at a heating rate ${\beta}=10^{\circ}C/min$ in the range $T=35^{\circ}C{\sim}950^{\circ}C$. The as-measured TG curves confirm that $Bi_xSe_{100-x}$ samples were thermally stable with minor loss at $T{\leq}400^{\circ}C$ and mass loss starts to decrease up to $600^{\circ}C$, beyond which trivial mass loss was observed. These TG curves were used to estimate molar (Se/Bi)-ratios of $Bi_xSe_{100-x}$ samples, which were not in accordance with initial composition. Shaping features of conversion curves ${\alpha}(T)-T$ of $Bi_xSe_{100-x}$ samples combined with a reliable flow chart were used to reduce kinetic mechanisms that would have caused their thermal mass loss to few nth-order reaction models of the form $f[{\alpha}(T)]{\propto}[1-{\alpha}(T)]^n$ (n=1/2, 2/3, and 1). The constructed ${\alpha}(T)-T$ and $(d{\alpha}(T)/dT)-T$ curves were analyzed using Coats-Redfern (CR) and Achar-Brindley-Sharp (ABS) kinetic formulas on basis of these model functions, but the linearity of attained plots were good in a limited ${\alpha}(T)-region$. The applicability of CR and ABS methods, with model function of kinetic reaction mechanism R0 (n=0), was notable as they gave best linear fits over much broader ${\alpha}(T)-range$.

• Elastomers and Composites
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• 제23권3호
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• pp.213-222
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• 1988

The thermal decomposition of poly(n-butyl methacrylate)(Pn-BMA) was studied using a dynamic and isothermal thermogravimetry in nitrogen gas with 50ml/min at several heating rates from 1 to $20^{\circ}C/min$, and at several heating temperature from 320 to $370^{\circ}C$. The mathematical techniques used for calculation of activation energy were Kissinger, Anderson, Chatterjee-Conrad, Friedman, Fuoss, Ozawa and isolthermal method. The range of activation energies obtained using the several techniques was between 43 and 51Kcal/mol except Chatterjee-Conrad and this range agreed with each other very well. The thermal degradation of Pn-BMA was considered to be carried out by main chain scission.

• 공업화학
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• 제16권2호
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• pp.296-303
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• 2005

PVC와 ABC의 혼합물을 대상으로 혼합비에 따른 공열분해 특성과 CaO와 $Cu_2O$의 첨가효과를 TG와 GC-MS를 이용하여 연구하였다. $500^{\circ}C$의 등온실험에서 ABS의 혼합비율이 증가할수록 스티렌 단량체와 방향족 화합물의 수율은 증가하였으며, BTX 화합물의 최대 수율은 PVC와 ABS의 혼합비가 4:1일 때 16.14% 정도임을 확인하였다. 금속산화물을 첨가한 경우 액상 생성물의 수율은 혼합비 0.4의 CaO를 첨가했을 때 73%와 0.4의 $Cu_2O$를 첨가했을 때 70%인 최대값을 얻을 수 있었으며, 각각 혼합비 0.5인 CaO와 1.0인 $Cu_2O$를 첨가했을 때 기상 생성물에 포함된 염화수소를 완전히 제거할 수 있었다. 본 연구의 실험조건에서는 염화수소를 완전히 제거할 수 있고, 가장 높은 액상 수율을 얻을 수 있는 반응조건은 $500^{\circ}C$에서 혼합비 0.5인 CaO나 혼합비 1.0인 $Cu_2O$를 첨가하는 것으로 사료된다.

• 한국건설순환자원학회논문집
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• 제8권2호
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• pp.219-226
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• 2020

지난 수십 년 동안 건축 분야에서 발생하는 이산화탄소 배출을 줄이기 위한 방법으로 다른 산업계의 폐기물 및 부산물을 시멘트의 대체재로 접목하기 위해 많은 노력이 있었다. 양식 산업에서 발생하는 굴 패각 폐기물은 특정 지역에서 대량으로 발생하며, 적절한 처리 방법의 부재로 인하여 일반적으로 매립되어지고 있다. 본 연구에서는 시멘트 대체재로 사용되어지고 있는 석회석 소성 점토 시멘트(LC³)의 주원료인 석회석의 대체재로써 굴 패각의 재활용 가능성을 평가하였다. 굴 패각 소성 점토 시멘트(OC³) 페이스트의 화학적·기계적 특성을 규명하기 위해 X-선 회절 분석, 등온 열량 측정, 압축강도 시험 및 열 중량 분석을 실시하였다. 결과적으로, OC³ 페이스트는 LC³와 동일한 포졸란 반응에 의해 유사한 강도 발현 및 반응성을 보여주었으며, 이를 통해 굴 패각이 LC³의 주 원료인 석회석의 대체재로써 사용할 수 있다는 것을 확인할 수 있었다.