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以5、7.5、10、15℃/min的升温速率对天然高分子材料杜仲胶进行了热重和微分热重(TG-DTG)测试,应用多重升温速率法中的Starink法、Kissinger法和Flynn-Wall-Ozawa法以及单一升温速率法中的Coats-Redfern法和Achar法对杜仲胶的非等温热解过程进行了计算,推断了分解的最概然机制函数f(α),并求得了相应的动力学参数——表观活化能(Ea)和指前因子(A)。研究表明,杜仲胶的热分解一步完成,在268℃左右开始分解,至459℃左右结束,且分解完全;升温速率的变化对杜仲胶的分解有影响,随着速率的升高,热分解曲线略微向高温移动,呈现了分解滞后现象;杜仲胶的热分解受化学反应机制控制,符合反应级数方程,Ea为191.54 kJ/mol,lnA为33.34;与文献报道的其他改性过的天然橡胶和合成橡胶相比,杜仲胶的热解特征参数说明了其具有较强的热稳定性,而指前因子亦呈现偏高趋势,说明一旦达到热分解点,杜仲胶的分解是相对快速的;经过对动力学的积分求解过程,计算推断杜仲胶在200℃下的热老化贮存期为170天。
The thermogravimetry and differential thermal gravimetric (TG-DTG) tests of natural polymeric materials were carried out at the heating rates of 5, 7.5, 10 and 15 ℃ / min. Starink, Kissinger and Flynn -Wall-Ozawa method and the Coats-Redfern method and the Achar method in a single heating rate method were used to calculate the non-isothermal pyrolysis process of Eucommia ulmoides gum, and the most general mechanism function f (α) of the decomposition was deduced and obtained The corresponding kinetic parameters - apparent activation energy (Ea) and pre-exponential factor (A). The results showed that the thermal decomposition of Eucommia ulmoides gum was completed in one step and started to decompose at around 268 ℃ and ended at about 459 ℃, and the decomposition was complete. The change of heating rate had an effect on the decomposition of Eucommia gum. With the increase of the rate, the thermal decomposition curve The thermal decomposition of Eucommia ulmoides gum was controlled by the chemical reaction mechanism and accorded with the reaction order equation with Ea of 191.54 kJ / mol and lnA of 33.34. Compared with other modified natural rubber reported in the literature, Compared with the synthetic rubber, the pyrolysis characteristic parameters of Eucommia gum showed that it has strong thermal stability, while the pre-exponential factor also showed a high tendency, indicating that once the thermal decomposition point is reached, the decomposition of the Eucommia gum is relatively fast; After the process of integral solution of kinetics, the thermal aging storage period of Eucommia at 200 ℃ is deduced to be 170 days.