没食子酸的热稳定性研究

利用TG-DTG技术测得没食子酸在氮气气氛中不同升温速率下的热分解曲线,协同使用Achar法和Coats-Redfern法两种方法同时进行动力学处理,根据热分解的表观活化能(Ea)和指前因子(A)计算推断没食子酸的贮存期。随着升温速率的提高,没食子酸的热分解温度逐渐升高;没食子酸热分解三步的机理都是化学反应控制,对应的函数名称是反应级数方程;经Gaussian模拟和热重数据分析结合,没食子酸在第一步分解时,失去0.5个O原子;第二步分解时失去0.5个O原子和1个CO2;根据第一步热分解的Ea和A推断,在室温25℃下,没食子酸的贮存期为1.5～2年。

Thermal Stability of Gallic Acid

Thermal decomposing curves of gallic acid in different heating speeds were obtained in the nitrogen atmosphere by TG-DTG techniques.Two analysis methods of Achar and Coats-Redfern were used to speculate the probable mechanism of thermal decomposing reaction and the kinetic parameters.The shelf life of gallic acid at room temperature was calculated by the kinetic parameters of the first stage.With the increasing of the heating rate,thermal decomposing tempreture of gallic acid rose.The most probable kinetic mechanisms of the three-stage thermal decomposition were all chemical reactions,and the corresponding mechanisms followed on reaction order.In accordance with the data of TG and Gaussian,one molecule of gallic acid lost 0.5 atom O at the fisrt-stage,and lost another 0.5 atom O and a molecule CO2 at the second stage.The shelf life of gallic acid at room temperature was about 1.5-2 years.