Buchenau U
Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS-1) and Institute for Complex Systems (ICS-1), 52425 Jülich, Germany.
Phys Rev E. 2022 Aug;106(2-1):024601. doi: 10.1103/PhysRevE.106.024601.
The shear misfit model for highly viscous flow is based upon a theoretical prediction for its terminal stage in terms of irreversible Eshelby relaxations in five-dimensional shear space. The model is shown to predict a small δ-function (Debye peak) in the dielectric spectrum, in agreement with experimental evidence. It is extended to density fluctuations, and a relation between adiabatic and isothermal compressibility jumps at the glass transition is derived. The model is applied to high-precision measurements of the shear, dielectric, and bulk relaxation data in two vacuum pump oils and in squalane, a short chain polymer with a strong secondary relaxation peak. The terminal stage of aging data in squalane demonstrates that the adiabatic density fluctuations contribute a fast component to the thermal expansion, explaining why the thermal expansion seems to equilibrate a bit faster than the dynamic heat capacity.
高粘性流动的剪切失配模型基于对其终态的理论预测，该预测是根据五维剪切空间中的不可逆埃舍尔比弛豫得出的。结果表明，该模型能预测介电谱中的一个小δ函数（德拜峰），与实验证据相符。它被扩展到密度涨落，并推导出玻璃化转变时绝热和等温压缩率跃变之间的关系。该模型应用于两种真空泵油和角鲨烷（一种具有强二级弛豫峰的短链聚合物）的剪切、介电和体弛豫数据的高精度测量。角鲨烷老化数据的终态表明，绝热密度涨落对热膨胀有一个快速贡献分量，解释了为什么热膨胀似乎比动态热容量平衡得稍快一些。
