Vyazovkin Sergey
Department of Chemistry, University of Alabama at Birmingham, 901 S. 14th Street, Birmingham, AL 35294, USA.
Phys Chem Chem Phys. 2016 Jul 28;18(28):18643-56. doi: 10.1039/c6cp02491b. Epub 2016 May 3.
This review deals with the phenomenon of variable activation energy frequently observed when studying the kinetics in the liquid or solid phase. This phenomenon commonly manifests itself through nonlinear Arrhenius plots or dependencies of the activation energy on conversion computed by isoconversional methods. Variable activation energy signifies a multi-step process and has a meaning of a collective parameter linked to the activation energies of individual steps. It is demonstrated that by using appropriate models of the processes, the link can be established in algebraic form. This allows one to analyze experimentally observed dependencies of the activation energy in a quantitative fashion and, as a result, to obtain activation energies of individual steps, to evaluate and predict other important parameters of the process, and generally to gain deeper kinetic and mechanistic insights. This review provides multiple examples of such analysis as applied to the processes of crosslinking polymerization, crystallization and melting of polymers, gelation, and solid-solid morphological and glass transitions. The use of appropriate computational techniques is discussed as well.
本综述探讨了在研究液相或固相动力学时经常观察到的活化能变化现象。这种现象通常通过非线性阿伦尼乌斯图或通过等转化率方法计算的活化能与转化率的依赖关系表现出来。可变活化能意味着一个多步过程，并且具有与各个步骤的活化能相关的集体参数的含义。结果表明，通过使用适当的过程模型，可以以代数形式建立这种联系。这使得人们能够以定量方式分析实验观察到的活化能依赖性，从而获得各个步骤的活化能，评估和预测过程的其他重要参数，并总体上获得更深入的动力学和机理见解。本综述提供了多个此类分析的例子，这些例子应用于交联聚合、聚合物的结晶和熔融、凝胶化以及固-固形态和玻璃化转变等过程。还讨论了适当计算技术的使用。
