金属氧化物催化热降解废聚甲基丙烯酸甲酯的动力学研究

利用热重分析的方法研究了MgO,CaO,Fe2O3,Al2O3,CuO5种金属氧化物对废聚甲基丙烯酸甲酯(PMMA)热降解过程的影响,并考察了该5种金属氧化物的催化活性,其由高到低的顺序为MgO>CaO>Fe2O3>Al2O3>CuO。提出了金属氧化物催化热降解PMMA时,金属离子与碳自由基侧链的羰基氧结合形成中间态,减弱酯基对自由基的共轭效应,从而增加自由基的活性,促使热降解反应进行的反应机理。同时还求得了在各种氧化物存在下热降解过程的表观活化能Ea。在MgO存在下,废有机玻璃热降解的Ea为153.08kJ/mol,指前因子A为4.27×1012min-1,初始热降解温度下的速率常数k为1.56×10-3min-1。

Kinetics of Thermal Degradation of Waste Poly (Methyl Methacrylate)on Metal Oxide Catalysts

Effects of five metal oxide catalysts on thermal degradation of waste poly(methyl methacrylate)were studied by thermogravimetric analysis(TGA).Their catalytic capabilities were found in the order of MgO>CaO>Fe_2O_3>Al_2O_3>CuO.The coordination between metallic ions of oxides and carbonyl oxygen of the polymer might weaken conjugative effect of ester group and therefore accelerate thermal degradation.The apparent activation energy for each degradation process was calculated by Coats-Redfern method.In case of MgO,the apparent activation energy of waste poly(methyl methacrylate) thermal degradation was 153.08kJ/mol,pre- exponential factor was 4.27×10 12min -1,rate constant of initial temperature of thermal degradation was 1.56×10 -3min -1.