Thermogravimetric analysis/differential scanning calorimeter(TGA/DSC)technique along with basic coal characteristics study is carried out for eighty coal samples of Indian coalfields,to determine spontaneous combustio...Thermogravimetric analysis/differential scanning calorimeter(TGA/DSC)technique along with basic coal characteristics study is carried out for eighty coal samples of Indian coalfields,to determine spontaneous combustion propensity behaviour of coal.TGA study of coal samples indicates that there is an increase in the mass of coal samples in the temperature range 150-350℃,which may be due to oxygen adsorption and absorption.The correlation and principal component analysis states that the component of proximate analysis(M_(ad),VM_(d),FR,and VR)have an acceptable correlation with the TGA experiments results i.e.,Tgsh and Tgign.Multiple fixed nonlinear regression analysis shows that thermogravimetry(TG)experiment results Tgign may be the best index to categorise/classify the coal as per their susceptibility towards spontaneous combustion.The authors proposed four groups of classification as per their propensity towards spontaneous combustion depending upon the moisture(M_(ad)),volatile matter(VM_(d)),and TG ignition temperature from differential thermogravimetric(DTG)curve(Tgign)using hierarchal clustering analysis.The coal samples of different seams from Indian coalfield may be classified into four different clusters,viz.very highly/extremely susceptible(Tgign<260℃),highly susceptible(260℃≤Tgign<290℃),moderately susceptible(290℃≤Tgign≤320℃),and poorly susceptible(Tgign>320℃).The field observations and TGA/DSC experiment results with the following statistical analysis substantiate a similar assessment.展开更多
Three thermal analytical techniques such as differential scanning calorimetry(DSC), thermal gravimetric analysis(TGA) using five heating rates, and DSC-Fourier Transform Infrared(DSCFTIR) microspectroscopy using one h...Three thermal analytical techniques such as differential scanning calorimetry(DSC), thermal gravimetric analysis(TGA) using five heating rates, and DSC-Fourier Transform Infrared(DSCFTIR) microspectroscopy using one heating rate, were used to determine the thermal characteristics and the dehydration process of aspartame(APM) hemihydrate in the solid state.The intramolecular cyclization process of APM anhydrate was also examined. One exothermic and four endothermic peaks were observed in the DSC thermogram of APM hemihydrate,in which the exothermic peak was due to the crystallization of some amorphous APM caused by dehydration process from hemihydrate to anhydride. While four endothermic peaks were corresponded to the evaporation of absorbed water, the dehydration of hemihydrate, the diketopiperazines(DKP) formation via intramolecular cyclization, and the melting of DKP, respectively. The weight loss measured in TGA curve of APM hemihydrate was associated with these endothermic peaks in the DSC thermogram. According to the Flynn–Wall–Ozawa(FWO)model, the activation energy of dehydration process within 100–150 °C was about 218 ± 11 kJ/mol determined by TGA technique. Both the dehydration and DKP formation processes for solid-state APM hemihydrate were markedly evidenced from the thermal-responsive changes in several specific FTIR bands by a single-step DSC-FTIR microspectroscopy.展开更多
DSC-TGA was used for screening of commercially available and synthesized catalyst for the degradation of polypropylene (PP). In this study, all the runs were performed with 50% load of the catalyst and the results wer...DSC-TGA was used for screening of commercially available and synthesized catalyst for the degradation of polypropylene (PP). In this study, all the runs were performed with 50% load of the catalyst and the results were compared with those of PP + 50% pure silica having no catalytic activity. The degradation behavior of PP using catalyst Zeolyst-713 exhibited much higher degradation activity among the other catalysts used in this study. Moreover, it contributed to lowering of initial stage temperature showing a shape-selective effect. DSC-TGA tools such as Ton, Tmax, T99%, activation energy, enthalpy change in the process and coke content were used for screening. It was concluded that the pore construction and unique acid properties of the Zeolyst-713 as well as proper reaction temperatures were significant influential factors to fully exert this effect. In this work, kinetics of catalytic thermogravimetric degradation of PP used for domestic purposes was investigated using Alumino-silicate catalyst. Zeolyst-713 was observed to lower activation energy and enhances degradation activity in comparison with thermal degradation without a catalyst.展开更多
The thermal decomposition of dicumyl peroxide under the flow nitrogen atmosphere was studied by DSC-TG technique.The non-isothermal kinetics parameters were analyzed by means of the Kissinger and Flynn-Wall-Ozawa meth...The thermal decomposition of dicumyl peroxide under the flow nitrogen atmosphere was studied by DSC-TG technique.The non-isothermal kinetics parameters were analyzed by means of the Kissinger and Flynn-Wall-Ozawa methods,and the thermal decomposition mechanism of dicumyl peroxide was also studied with the Satava-Sestak method.The results showed that there was little difference between kinetic parameters calculated by DSC plot and DTG plot,the apparent activation energy and pre-exponential factor were 120.83 kJ·mol-1 and 9.12×1011s-1,respectively.The thermal decomposition mechanism of dicumyl peroxide in nitrogen was controlled by interface reaction R3.展开更多
基金M/s CIL R&D Board,Kolkata(CIL/R&D/01/60/2016)for their financial support.
文摘Thermogravimetric analysis/differential scanning calorimeter(TGA/DSC)technique along with basic coal characteristics study is carried out for eighty coal samples of Indian coalfields,to determine spontaneous combustion propensity behaviour of coal.TGA study of coal samples indicates that there is an increase in the mass of coal samples in the temperature range 150-350℃,which may be due to oxygen adsorption and absorption.The correlation and principal component analysis states that the component of proximate analysis(M_(ad),VM_(d),FR,and VR)have an acceptable correlation with the TGA experiments results i.e.,Tgsh and Tgign.Multiple fixed nonlinear regression analysis shows that thermogravimetry(TG)experiment results Tgign may be the best index to categorise/classify the coal as per their susceptibility towards spontaneous combustion.The authors proposed four groups of classification as per their propensity towards spontaneous combustion depending upon the moisture(M_(ad)),volatile matter(VM_(d)),and TG ignition temperature from differential thermogravimetric(DTG)curve(Tgign)using hierarchal clustering analysis.The coal samples of different seams from Indian coalfield may be classified into four different clusters,viz.very highly/extremely susceptible(Tgign<260℃),highly susceptible(260℃≤Tgign<290℃),moderately susceptible(290℃≤Tgign≤320℃),and poorly susceptible(Tgign>320℃).The field observations and TGA/DSC experiment results with the following statistical analysis substantiate a similar assessment.
文摘Three thermal analytical techniques such as differential scanning calorimetry(DSC), thermal gravimetric analysis(TGA) using five heating rates, and DSC-Fourier Transform Infrared(DSCFTIR) microspectroscopy using one heating rate, were used to determine the thermal characteristics and the dehydration process of aspartame(APM) hemihydrate in the solid state.The intramolecular cyclization process of APM anhydrate was also examined. One exothermic and four endothermic peaks were observed in the DSC thermogram of APM hemihydrate,in which the exothermic peak was due to the crystallization of some amorphous APM caused by dehydration process from hemihydrate to anhydride. While four endothermic peaks were corresponded to the evaporation of absorbed water, the dehydration of hemihydrate, the diketopiperazines(DKP) formation via intramolecular cyclization, and the melting of DKP, respectively. The weight loss measured in TGA curve of APM hemihydrate was associated with these endothermic peaks in the DSC thermogram. According to the Flynn–Wall–Ozawa(FWO)model, the activation energy of dehydration process within 100–150 °C was about 218 ± 11 kJ/mol determined by TGA technique. Both the dehydration and DKP formation processes for solid-state APM hemihydrate were markedly evidenced from the thermal-responsive changes in several specific FTIR bands by a single-step DSC-FTIR microspectroscopy.
文摘DSC-TGA was used for screening of commercially available and synthesized catalyst for the degradation of polypropylene (PP). In this study, all the runs were performed with 50% load of the catalyst and the results were compared with those of PP + 50% pure silica having no catalytic activity. The degradation behavior of PP using catalyst Zeolyst-713 exhibited much higher degradation activity among the other catalysts used in this study. Moreover, it contributed to lowering of initial stage temperature showing a shape-selective effect. DSC-TGA tools such as Ton, Tmax, T99%, activation energy, enthalpy change in the process and coke content were used for screening. It was concluded that the pore construction and unique acid properties of the Zeolyst-713 as well as proper reaction temperatures were significant influential factors to fully exert this effect. In this work, kinetics of catalytic thermogravimetric degradation of PP used for domestic purposes was investigated using Alumino-silicate catalyst. Zeolyst-713 was observed to lower activation energy and enhances degradation activity in comparison with thermal degradation without a catalyst.
文摘The thermal decomposition of dicumyl peroxide under the flow nitrogen atmosphere was studied by DSC-TG technique.The non-isothermal kinetics parameters were analyzed by means of the Kissinger and Flynn-Wall-Ozawa methods,and the thermal decomposition mechanism of dicumyl peroxide was also studied with the Satava-Sestak method.The results showed that there was little difference between kinetic parameters calculated by DSC plot and DTG plot,the apparent activation energy and pre-exponential factor were 120.83 kJ·mol-1 and 9.12×1011s-1,respectively.The thermal decomposition mechanism of dicumyl peroxide in nitrogen was controlled by interface reaction R3.
