【作者】 刘欣；

【导师】 王利民；

【作者基本信息】 燕山大学 ， 材料学， 2020， 硕士

【摘要】 弛豫在玻璃转变和玻璃态材料中普遍存在,在主导弛豫过程的结构弛豫中展示出明显的偏离指数性的动力学行为,液体的结构弛豫取决于其微观基本结构单元之间的相互作用,而其中的非指数性正是这些结构单元在动力学上耦合强度的直接反应。对于多组分体系,混合行为可以有效提高非晶形成能力,而且玻璃化转变对组分的依赖关系被证明对研究玻璃形成混合物的结构弛豫动力学具有重要意义。二元系统作为一种最简单的多组分系统,因其通过改变组分来调节体系相互作用的便利性而受到广泛的关注。过去的研究发现,即使一个体系的相互作用或结构发生很小的变化,也会影响玻璃转变过程。尽管分子间作用被认为对于理解非指数动力学极其重要,但混合体系中各组元到底如何影响非指数弛豫动力学变化,什么参量控制主导混合体系弛豫分布宽度的问题一直没有解决。弄清这一问题对于理解相互作用力对玻璃转变的影响和认识结构弛豫非指数动力学本质具有重要意义。为了解玻璃化转变过程中非指数性参数与混合热之间的关联,本文利用差示扫描量热仪和宽频介电谱仪对具有玻璃形成能力的理想混合溶液、正混合热溶液和负混合热溶液三种不同混合模式的二元溶液(methyl m-toluate---methyl o-toluate,2-ethyl pyridine---n-ethyl piperidine,1,2-propanediamine---propylene glycol)的结构弛豫进行了测量,使用TNMH方程和KWW方程对基本实验结果进行分析处理。对比分析发现三种不同混合模式的玻璃形成体系,混合焓和非指数性动力学具有很强的关联。在焓弛豫中,正混合焓体系展现出弛豫分布窄化现象,负混合焓体系弛豫分布变宽。同时弛豫分布宽度的偏离程度和混合焓的大小正相关,混合焓数值越大,弛豫分布宽度偏离程度越大。而在介电弛豫中,非指数性参数变化更为复杂,不仅受到混合焓的影响,而且对介电强度有很大的依赖关系,当两组分介电强度差异很大时,介电强度高的组分对混合后的弛豫分布宽度影响更大。更多还原

【Abstract】 Relaxation is ubiquitous in glass transition and glassy materials.It exhibits obvious dynamic behavior that deviates from exponential in the structural relaxation that dominates the relaxation process.The structural relaxation of the liquid depends on its microscopic basic structural units.The interaction,and the non-exponential nature is the direct reaction of the dynamic coupling strength of these structural units.For multi-component systems,the mixing behavior can effectively improve the ability of forming glass,and the dependence of the glass transition on the components has proved to be of great significance for studying the structural relaxation dynamics of glass-forming mixtures.As a simplest multi-component system,the binary system has attracted extensive attention because of the convenience of adjusting the system interaction by changing the components.Previous research has found that even a small change in the interaction or structure of a system can affect the glass transition process.Although intermolecular interactions are extremely important for understanding non-exponential dynamics,the question of how each component in a mixed system affects the non-exponential relaxation dynamics and what parameters control the width of the relaxation distribution of the dominant mixed system has not been solved.To clarify this issue is of great significance for understanding the effect of interaction forces on the glass transition and for understanding the nature of non-exponential dynamics of structural relaxation.In order to understand the relationship between non-exponential parameters and the heat of mixing during the glass transition,this paper uses differential scanning calorimeters and wideband dielectric spectrometers to measure the structure relaxation of three different binary mixed solutions-ideal mixed solutions with glass forming ability,positive mixed thermal solutions and negative mixing(methyl m-toluate---methyl o-toluate,2-ethyl pyridine---n-ethyl piperidine,1,2-propanediamine---propylene glycol),and the TNMH equation and KWW equation are used to analyze the experimental data.Comparative analysis found that the glass formation systems of three different mixing modes have a strong correlation between mixing enthalpy and non-exponential kinetics.Inenthalpy relaxation,the positive mixed enthalpy system exhibits a narrowing of the relaxation distribution,and the negative mixed enthalpy system broadens the relaxation distribution.Non-exponentiality is more complicated in dielectric relaxation,which is not only affected by the mixing enthalpy,but also has a great dependence on the molecular dipole moment.更多还原