Universal representation of viscosity in glass forming liquids
Universal representation of viscosity in glass forming liquids
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DOI：
10.1016/s0022-3093(97)00365-7
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发表时间：
1998
影响因子：
3.5
通讯作者：
E. Rössler;K. Hess;V. Novikov
中科院分区：
文献类型：
--
作者：
E. Rössler;K. Hess;V. Novikov
分析了脆性聚合物、强聚合物和非聚合物玻璃成型剂的粘度η(T)与温度的关系。引入了一个温度T_x，它标志着高温和低温区域的边界，其中采用了不同的方法来对η=η(T)进行内插。在T<；通过用因子F=Tx/(Tx−Tg)标度量(Tg/T−1)，得到聚合物和非聚合物玻璃成形器的TxA主曲线，其中Tgi是玻璃化转变温度。F通过F≅0.079m与陡度参数m相关。随着分子量的增大，非聚合物体系的主曲线向聚合物体系的主曲线连续过渡。用模式耦合理论分析了系统的动态磁化率，发现Tx接近临界温度T。初步认为，Tx和Tg之间的间隔的大小决定了易损性的程度。在T>；Tx出现偏离主曲线的情况，Vogel-Fulcher-Tammann方程对最高温度有很好的拟合。T<；Tx；处的两条主曲线可以用几个公式进行插补。
Temperature dependence of the viscosity η(T) of fragile and strong polymer and non-polymer glass formers was analyzed. A temperature Txwas introduced which marks the boundary between a high- and low-temperature regime, where different approaches are applied to interpolate η=η(T). At T<Txa master curve is obtained for polymer and non-polymer glass formers by scaling the quantity (Tg/T−1) with a factor F=Tx/(Tx−Tg) where Tgis the glass transition temperature. F is related to the steepness parameter m via F≅0.079m. A continuous transition from the master curve of non-polymer systems to the one of polymers is found if molecular weight is systematically increased. Txis found to be close to the critical temperature Tcreported from analyses of the dynamic susceptibility by mode coupling theory. It is tentatively concluded that the magnitude of the interval between Txand Tgdefines the degree of fragility. At T>Txdeviations from the master curves occur, and the Vogel–Fulcher–Tammann equation provides a very good fit to highest temperatures. The two master curves at T<Txcan be interpolated by several formulae.