利用热重-微分热重技术研究了二炔丙基双酚A醚聚合物(PDPEBA)在氮气气氛中的非等温热分解过程,探讨了聚合物在不同升温速率下的热分解机理,并采用2种模型法和5种非模型法对二炔丙基双酚A醚聚合物热分解动力学三因子(E、A、f(a))进行计...利用热重-微分热重技术研究了二炔丙基双酚A醚聚合物(PDPEBA)在氮气气氛中的非等温热分解过程,探讨了聚合物在不同升温速率下的热分解机理,并采用2种模型法和5种非模型法对二炔丙基双酚A醚聚合物热分解动力学三因子(E、A、f(a))进行计算。结果表明,7种方法计算所得平均活化能及指前因子分别为E=176.30 k J/mol,lg A=10.43s-1;聚合物热分解阶段符合三维扩散机理,其对应的机理微分函数为f(α)=32(1-α)43×(1-α)-1[-3/1]-1,积分函数为g(α)=(1-α)-1[-3/1]2。展开更多
The pentlandite exsolution from monosulfide solid solution （mss）/pyrrhotite exsolution is a complex multi-step process, including nucleation, new phase growth and atomic diffusion, and lamellae coarsening. Some of t...The pentlandite exsolution from monosulfide solid solution （mss）/pyrrhotite exsolution is a complex multi-step process, including nucleation, new phase growth and atomic diffusion, and lamellae coarsening. Some of these steps occur in sequence, others simultaneously. These make its kinetic analysis difficult, as the mechanisms cannot be elucidated in detail. In mineral reactions of this type, the true functional form of the reaction model is almost never known, and the Arrhenius parameters determined by the classic Avrami method are skewed to compensate for errors in the model. The model-free kinetics allows a universal determination of activation energy. Kinetic study of pentlandite exsolution from mss/pyrrhotite was performed over the temperature range 200 to 300℃. For mss/pyrrhotite with bulk composition （Fe0.77Ni0.19）S, activation energy of pentlandite exsolution, Ea, varies from 49.6 kJ · mol^-1 at the beginning of reaction （nucleation is dominant） to 20.7 kJ · mol^-1 at the end （crystal growth is dominant）. In general, the activation energy varies during the course of solid reaction with the extent of reaction. The surrounding environment of reactant atoms affects the atom＇s activity and more or less accounts for changes of activation energy Ea.展开更多
采用非模型拟合法研究了Mg_(17)Al_(12)储氢合金燃烧合成过程动力学,为今后规模化制备该合金提供理论指导。首先比较不同样品燃烧合成过程热效应及产物相组分,指出压片预处理方法及小尺寸Al粉均有利于促进合金化反应;然后分别采用Kissin...采用非模型拟合法研究了Mg_(17)Al_(12)储氢合金燃烧合成过程动力学,为今后规模化制备该合金提供理论指导。首先比较不同样品燃烧合成过程热效应及产物相组分,指出压片预处理方法及小尺寸Al粉均有利于促进合金化反应;然后分别采用Kissinger法和Flynn-Wall-Ozawa法计算出该反应活化能分别为140.5和142 k J/mol,对应的最概然机制函数为G(α)=[-ln(1-α)]1/3,符合Avrami-Erofeev方程的随机成核和随后生长机制。最后通过反应前后期产物相组成分析,揭示该燃烧合成过程中Mg-Al合金化反应机制。展开更多
文摘利用热重-微分热重技术研究了二炔丙基双酚A醚聚合物(PDPEBA)在氮气气氛中的非等温热分解过程,探讨了聚合物在不同升温速率下的热分解机理,并采用2种模型法和5种非模型法对二炔丙基双酚A醚聚合物热分解动力学三因子(E、A、f(a))进行计算。结果表明,7种方法计算所得平均活化能及指前因子分别为E=176.30 k J/mol,lg A=10.43s-1;聚合物热分解阶段符合三维扩散机理,其对应的机理微分函数为f(α)=32(1-α)43×(1-α)-1[-3/1]-1,积分函数为g(α)=(1-α)-1[-3/1]2。
文摘The pentlandite exsolution from monosulfide solid solution （mss）/pyrrhotite exsolution is a complex multi-step process, including nucleation, new phase growth and atomic diffusion, and lamellae coarsening. Some of these steps occur in sequence, others simultaneously. These make its kinetic analysis difficult, as the mechanisms cannot be elucidated in detail. In mineral reactions of this type, the true functional form of the reaction model is almost never known, and the Arrhenius parameters determined by the classic Avrami method are skewed to compensate for errors in the model. The model-free kinetics allows a universal determination of activation energy. Kinetic study of pentlandite exsolution from mss/pyrrhotite was performed over the temperature range 200 to 300℃. For mss/pyrrhotite with bulk composition （Fe0.77Ni0.19）S, activation energy of pentlandite exsolution, Ea, varies from 49.6 kJ · mol^-1 at the beginning of reaction （nucleation is dominant） to 20.7 kJ · mol^-1 at the end （crystal growth is dominant）. In general, the activation energy varies during the course of solid reaction with the extent of reaction. The surrounding environment of reactant atoms affects the atom＇s activity and more or less accounts for changes of activation energy Ea.
文摘采用非模型拟合法研究了Mg_(17)Al_(12)储氢合金燃烧合成过程动力学,为今后规模化制备该合金提供理论指导。首先比较不同样品燃烧合成过程热效应及产物相组分,指出压片预处理方法及小尺寸Al粉均有利于促进合金化反应;然后分别采用Kissinger法和Flynn-Wall-Ozawa法计算出该反应活化能分别为140.5和142 k J/mol,对应的最概然机制函数为G(α)=[-ln(1-α)]1/3,符合Avrami-Erofeev方程的随机成核和随后生长机制。最后通过反应前后期产物相组成分析,揭示该燃烧合成过程中Mg-Al合金化反应机制。
