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
目的:探究中国药典和世界卫生组织双氰胺熔点对照品熔点差异的原因。方法:采用差示扫描量热分析(DSC)和热重/差热同步分析(TGA/SDTA)研究双氰胺熔点对照品的熔融过程,DSC升温速率10℃·min-1,干燥气N2流速50 m L·min-1,TGA/SDT...目的:探究中国药典和世界卫生组织双氰胺熔点对照品熔点差异的原因。方法:采用差示扫描量热分析(DSC)和热重/差热同步分析(TGA/SDTA)研究双氰胺熔点对照品的熔融过程,DSC升温速率10℃·min-1,干燥气N2流速50 m L·min-1,TGA/SDTA升温速率20℃·min-1,干燥气N2流速25 m L·min-1;并进一步通过HPLC法分析熔融前、中、后的样品。结果:差示扫描量热分析和热重/差热同步分析发现3个对照品的热力学行为基本一致,提示熔融后期可能已经热降解;HPLC法进一步证实双氰胺的熔融过程伴有部分降解。结论:热稳定性可能是造成中国药典和世界卫生组织双氰胺熔点对照品熔点差异的原因,双氰胺继续作为熔点对照品值得商榷。展开更多
目的:研究头孢唑林钠不同晶体之间的转变及转变条件。方法:利用粉末 X 射线衍射(XRD)法分析了固体头孢唑林钠在不同的温度、湿度环境中α晶体、β晶体及无定型粉末之间的转变;并通过差示扫描量热(DSC)、热重分析(TGA)、程序升温粉末 X ...目的:研究头孢唑林钠不同晶体之间的转变及转变条件。方法:利用粉末 X 射线衍射(XRD)法分析了固体头孢唑林钠在不同的温度、湿度环境中α晶体、β晶体及无定型粉末之间的转变;并通过差示扫描量热(DSC)、热重分析(TGA)、程序升温粉末 X 射线衍射等方法分析了晶体转变的条件。结果:在60℃、相对湿度45%-75%的环境中,头孢唑林钠α晶体可以转变为β晶体;无定型头孢唑林钠在向α晶体转变过程中也会有β晶体的出现。结论:在较高的温度、湿度环境中有利于头孢唑林钠α晶体向β晶体转变。展开更多
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.
文摘目的:探究中国药典和世界卫生组织双氰胺熔点对照品熔点差异的原因。方法:采用差示扫描量热分析(DSC)和热重/差热同步分析(TGA/SDTA)研究双氰胺熔点对照品的熔融过程,DSC升温速率10℃·min-1,干燥气N2流速50 m L·min-1,TGA/SDTA升温速率20℃·min-1,干燥气N2流速25 m L·min-1;并进一步通过HPLC法分析熔融前、中、后的样品。结果:差示扫描量热分析和热重/差热同步分析发现3个对照品的热力学行为基本一致,提示熔融后期可能已经热降解;HPLC法进一步证实双氰胺的熔融过程伴有部分降解。结论:热稳定性可能是造成中国药典和世界卫生组织双氰胺熔点对照品熔点差异的原因,双氰胺继续作为熔点对照品值得商榷。
文摘目的:研究头孢唑林钠不同晶体之间的转变及转变条件。方法:利用粉末 X 射线衍射(XRD)法分析了固体头孢唑林钠在不同的温度、湿度环境中α晶体、β晶体及无定型粉末之间的转变;并通过差示扫描量热(DSC)、热重分析(TGA)、程序升温粉末 X 射线衍射等方法分析了晶体转变的条件。结果:在60℃、相对湿度45%-75%的环境中,头孢唑林钠α晶体可以转变为β晶体;无定型头孢唑林钠在向α晶体转变过程中也会有β晶体的出现。结论:在较高的温度、湿度环境中有利于头孢唑林钠α晶体向β晶体转变。
