刚性分子玻璃形成体中二级弛豫的动力学研究

发布时间：2018-02-14 21:37

本文关键词： 玻璃转变结构弛豫 JG-??弛豫二级弛豫耦合模型　出处：《燕山大学》2015年硕士论文　论文类型：学位论文

【摘要】：二级弛豫一般分为两类,一类叫快???弛豫,另一类叫慢???弛豫(也叫做JG-??弛豫)。研究发现,金属玻璃中JG-?弛豫?和非晶的稳定性存在一定的相关性,并且JG-??弛豫和结构弛豫在弛豫时间上紧密相关,故JG-??弛豫越来越引起中外学者的广泛关注。不同的弛豫动力学从不同角度反映了过冷液体和玻璃态的内在微观结构以及运动规律,对过冷液体和玻璃态中弛豫动力学的研究是认识玻璃转变物理本质的有效方法。首先,本文利用宽频介电谱技术,对三个结构相似的刚性玻璃形成液体1-methylindole(1MID)、5h-5-methyl-6,7-dihydrocyclopentapyrazine(MDCP)和Quinaldine(QN)的弛豫动力学进行了研究,并分析了三个刚性分子结构弛豫和二级弛豫在弛豫时间上的关联性,实验结果发现在1MID的介电谱中能观察到一个明显的二级弛豫,但是在MDCP和QN的介电谱中却没有出现明显的二级弛豫,并且1MID的结构弛豫峰的频率f?和二级弛豫峰的频率f?之间不符合耦合模型??Coupling Model?,?DCP和QN则符合耦合模型。然后,将1MID和Toluene的介电损耗谱做对比,发现1MID中的二级弛豫并不是真正的JG-??弛豫。接着,利用红外谱和文献调研证明了1MID的异常的二级弛豫并不是由于氢键诱导团簇和分子内的运动引起的。最后得出结论:????1MID异常的二级弛豫主要是因为分子所在平面的偶极矩远大于垂直于分子所在平面的偶极矩,即刚性分子1MID的二级弛豫是1MID自己所在平面运动引起的,故JG-??弛豫很有可能涉及到垂直于分子平面的运动;(2)MDCP在分子所在平面有很小的偶极矩,结构弛豫峰高频侧斜率的变化说明MDCP符合耦合模型。(3)QN具有和1MID一样大的分子平面内的运动,但是由于QN具有很小的耦合参数,所以没有看到明显的二级弛豫。结合以上结论,本文建立了刚性分子的运动模型,该模型解释了刚性分子中JG-??弛豫所对应分子的运动形式,进而引发了相关研究人员对JG-??弛豫本质的进一步思考。
[Abstract]:Second order relaxation is generally divided into two categories, one is called fast? ? ? Relaxation, another type called slow? ? ? Relaxation (also known as JG-? ? The study found that JG-? Relaxation? There is a certain correlation with the stability of amorphous, and JG-? ? Relaxation and structural relaxation are closely related to relaxation time, so JG-? ? Relaxation has attracted more and more attention from domestic and foreign scholars. Different relaxation dynamics reflect the internal microstructure and motion law of supercooled liquid and glass state from different angles. The study of relaxation kinetics in supercooled liquids and glass states is an effective method for understanding the physical nature of glass transition. The relaxation kinetics of three rigid glass-forming liquids 1-methylindoleine 1MID-5h-5-methyl-6-dihydrocyclopentapyrazinerazine (MDCP) and Quinaldinesia (QN) has been studied. The relationships between the relaxation time of three rigid molecular structures and the second order relaxation have been analyzed. The experimental results show that an obvious second-order relaxation can be observed in the dielectric spectra of 1MID, but there is no obvious second-order relaxation in the dielectric spectra of MDCP and QN, and the frequency of the structural relaxation peak of 1MID is f? And the frequency f? Does not fit the coupling model? ? Coupling Model? ,? DCP and QN fit the coupling model. Then, the dielectric loss spectra of 1MID and Toluene are compared and it is found that the second-order relaxation in 1MID is not the true JG-? ? The second order relaxation of 1MID is not caused by the hydrogen bond induced cluster and intramolecular motion. Finally, the conclusion is drawn that the second order relaxation of 1MID is not caused by the hydrogen bond induced cluster and intramolecular motion. ? ? ? The second order relaxation of 1mid anomaly is mainly due to the fact that the dipole moment of the plane in which the molecule is located is much larger than the dipole moment perpendicular to the plane in which the molecule is located, that is, the second-order relaxation of the rigid molecule 1MID is caused by the motion of the plane in which the rigid molecule is located. ? It is very likely that relaxation is related to the small dipole moment in the plane perpendicular to the molecular plane. The variation of the slope of the high frequency side of the structural relaxation peak indicates that MDCP accords with the coupling model. The QN is as large as 1MID in the molecular plane. However, due to the small coupling parameters of QN, there is no obvious second-order relaxation. Based on the above conclusions, the motion model of rigid molecules is established, which explains the JG--? ? Relaxation corresponds to the movement of molecules, which in turn triggers the researchers' response to the JG-? ? Further reflection on the essence of relaxation.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ171.1

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