摘要
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 natural polymeric material,gutta-percha,was non-isothermally analyzed by thermogravimetric and differential thermogravimetric techniques at different heating rates of 5,7.5,10,15 ℃/min under the nitrogen atmosphere.Thermal analysis kinetics methods of multi-heating rate methods （Starink,Kissinger and Flynn-Wall-Ozawa methods） and single heating rate methods （Coats-Redfern and Achar methods） were applied to infer the most probable reaction mechanism and calculate the corresponding kinetic parameters of apparent activation energy Ea and preexponential factor A.The results showed that thermal decomposition of gutta-percha began at 268 ℃ and ended at 459 ℃ with a complete mass loss.The increasing of heating rates had a significant effect on the decomposition.The TG-DTG curves moved to higher temperatures while a hysteresis effect of thermal decomposition occurred.The most probable thermal decomposition mechanism was Chemical Reaction,corresponding with Reaction Order Equation.The values of apparent activation energy Ea and pre-exponential factor lnA were 191.54 kJ/mol and 33.34,respectively.Compared with other modified natural or synthetic rubbers,characteristic parameters of gutta-percha revealed its strong thermostability while at high temperatures it decomposed fast.Through integral calculation for the differential kinetic equation,the storage time of heat resistance at 200 ℃ were 170 days.
出处
《林产化学与工业》
EI
CAS
CSCD
北大核心
2013年第6期7-13,共7页
Chemistry and Industry of Forest Products
基金
湖南省高校科技创新团队支持计划(湘教通(2010)212号)
湖南省科技厅项目(2012TP4020-2)
林产化工工程湖南省重点实验室开放课题资助(JDLC201206)
