论文标题
玻璃形成液体α松弛的流变模型及其与DC704和DC705的数据的比较
Rheological model for the alpha relaxation of glass-forming liquids and its comparison to data for DC704 and DC705
论文作者
论文摘要
在覆盖五十多年的放松时间变化的温度下，给出了两种硅油DC704和DC705的动态剪切模量数据。数据安装在先前显示的现象学模型的α部分，以很好地描述Squalane的动态剪切模量，该模量具有较大的beta过程[Hecksher \ Textit {et al。}，J。Chem。物理。 \ textbf {146}，154504（2017）];该模型的特征是Alpha和beta剪切合规性的添加性以及Alpha过程的高频衰减，其成比例的成绩为$ω^{ - 1/2} $，其中$ω$是角度频率。将该模型的Alpha部分的拟合与DC704和DC705数据的拟合与Havriliak-Negami类型模型，Barlow-Erginsav-Lamb模型和Cole-Davidson类型模型进行了比较。在所有温度下，最佳拟合是由鳞状模型的α部分获得的。这加强了所谓的$ \ sqrt {t} $ - 放松的猜想，导致高频衰减与$ω^{ - 1/2} $成比例，这是超冷液体α放松的一般特征。 Rev. E {\ bf 74}，021502（2006）; Nielsen \ textit {et al。}，J。Chem。物理。 \ textbf {130}，154508（2009）; pabst \ textit {et al。}，J。Phys。化学Lett。 \ textbf {12}，3685（2021）]。
Dynamic shear-modulus data are presented for the two silicone oils DC704 and DC705 for frequencies between 1 mHz and 10 kHz at temperatures covering more than five decades of relaxation-time variation. The data are fitted to the alpha part of a phenomenological model previously shown to describe well the dynamic shear modulus of squalane, which has a large beta process [Hecksher \textit{et al.}, J. Chem. Phys. \textbf{146}, 154504 (2017)]; that model is characterized by additivity of the alpha and beta shear compliance and by a high-frequency decay of the alpha process in proportion to $ω^{-1/2}$ in which $ω$ is the angular frequency. The fits of the alpha part of this model to the DC704 and DC705 data are compared to fits by a Havriliak-Negami type model, the Barlow-Erginsav-Lamb model, and a Cole-Davidson type model. At all temperatures the best fit is obtained by the alpha part of the squalane model. This strengthens the conjecture that so-called $\sqrt{t}$-relaxation, leading to high-frequency decays proportional to $ω^{-1/2}$, is a general characteristic of the alpha relaxation of supercooled liquids [Dyre, Phys. Rev. E {\bf 74}, 021502 (2006); Nielsen \textit{et al.}, J. Chem. Phys. \textbf{130}, 154508 (2009); Pabst \textit{et al.}, J. Phys. Chem. Lett. \textbf{12}, 3685 (2021)].
