聚羟基丁酸-戊酸的非等温热分解反应动力学

用非等温TG-DTA技术, 在5.0、10.0、15.0和20.0 K?min^-1线性升温条件下, 研究聚羟基丁酸-戊酸(PHBV)的热分解反应动力学. 结果表明, 分解过程分三个阶段：分解初期、分解中期和分解后期. 分解初期的机理函数为Avrami-Erofeev方程(n=1/2), 对应随机成核和随后生长机理, 表观活化能E_a(β→0)为69.44 kJ?mol^-1, 指前因子A(β→0)为106.27 s^-1；分解中期的机理函数为Avrami-Erofeev方程(n =2/5), 对应随机成核和随后生长机理, 表观活化能Ea(β→0)为117.64 kJ?mol^-1, 指前因子A(β→0)为10^11.48 s^-1；分解后期的机理函数为Mampel Power法则(n=1/3), 对应机理为幂函数法则, 表观活化能Ea(β→0)为116.64 kJ?mol^-1, 指前因子A(β→0)为10^8.68 s^-1.

Non-isothermal Decomposition Kinetics of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The thermal decomposition kinetics of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) has been investigated by means of non-isothermal TG-DTA with various heating rates of 5.0, 10.0, 15.0, and 20.0 K?min^-1. The result shows that the decomposition process of PHBV is composed of three stages：initial stage, medium stage, and end stage. The most probable kinetic function of the initial stage is the Avrami-Erofeev equation with n=1/2, and the corresponding machanism is controlled by random nuclear producing and growing process. The apparent activation energy (Ea(β→0)) and the pre-exponential constant(A(β→0)) are 69.44 kJ?mol^-1 and 10^6.27 s^-1 respectively. The most probable kinetic function of the medium stage is the Avrami-Erofeev equation with n=2/5, and the corresponding machanism is the same with the previous stage. The apparent activation energy (Ea(β→0)) and the pre-exponential constant (A(β→0)) are 117.64 kJ?mol^-1 and 10^11.48 s^-1 respectively. The most probable kinetic function of the end stage is the exponential function with n=1/3, and the corresponding mechanism follows Mampel Power theorem. The apparent activation energy(E_a(β→0)) and the pre-exponential constant (A(β→0)) are 116.64 kJ?mol^-1 and 10^8.68 s^-1 respectively.