Heat capacities and volumetric changes in the glass transition range: a constitutive approach based on the standard linear solid
Heat capacities and volumetric changes in the glass transition range: a constitutive approach based on the standard linear solid
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DOI：
10.1007/s00161-016-0551-9
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发表时间：
2017-01
影响因子：
2.6
通讯作者：
A. Lion;C. Mittermeier;M. Johlitz
中科院分区：
文献类型：
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作者：
A. Lion;C. Mittermeier;M. Johlitz
提出了一种新的方法来表示玻璃化转变。它是基于物理动机的线性粘弹性Poynting-Thomson模型的扩展。除了一个温度相关的阻尼元件和两个线性弹簧外，还引入了两个热应变元件。为了考虑比热的工艺依赖性并对其在玻璃化转变以下和以上的特性行为进行建模，亥姆霍兹自由能包含取决于温度历史和当前温度的额外贡献。该模型描述了玻璃形成材料的过程依赖的体积和热量行为，并定义了压力，体积应变和温度之间的函数关系。如果材料行为的等容部分的模型已经可用，例如有限粘弹性的模型，则热量和体积行为可以用当前方法表示。该模型允许计算等压和等容的封闭形式的热容。这种差异与工艺有关，在玻璃态和平衡态范围内趋向于经典表达式。仿真和理论研究证明了该模型的物理意义。
A novel approach to represent the glass transition is proposed. It is based on a physically motivated extension of the linear viscoelastic Poynting–Thomson model. In addition to a temperature-dependent damping element and two linear springs, two thermal strain elements are introduced. In order to take the process dependence of the specific heat into account and to model its characteristic behaviour below and above the glass transition, the Helmholtz free energy contains an additional contribution which depends on the temperature history and on the current temperature. The model describes the process-dependent volumetric and caloric behaviour of glass-forming materials, and defines a functional relationship between pressure, volumetric strain, and temperature. If a model for the isochoric part of the material behaviour is already available, for example a model of finite viscoelasticity, the caloric and volumetric behaviour can be represented with the current approach. The proposed model allows computing the isobaric and isochoric heat capacities in closed form. The differenceis process-dependent and tends towards the classical expression in the glassy and equilibrium ranges. Simulations and theoretical studies demonstrate the physical significance of the model.