THE MICROSCOPIC BASIS OF THE GLASS-TRANSITION IN POLYMERS FROM NEUTRON-SCATTERING STUDIES
THE MICROSCOPIC BASIS OF THE GLASS-TRANSITION IN POLYMERS FROM NEUTRON-SCATTERING STUDIES
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DOI：
10.1126/science.267.5206.1939
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发表时间：
1995-03-31
期刊：
影响因子：
56.9
通讯作者：
RICHTER, D
中科院分区：
文献类型：
--
作者：
FRICK, B;RICHTER, D
综述了近年来在玻璃化转变温度T-g以下和以上的聚合物微观动力学的中子散射实验。结果涵盖了玻璃中出现的不同动态过程：局部运动、振动和不同的松弛过程，如α-松弛和β-松弛。对于发生在T-g以上的α-松弛，可以将宏观尺度上适用于聚合物的时间-温度叠加原理推广到微观尺度。然而，这一原理不适用于接近T-g的温度。在T-g以下，频率为几百吉赫兹(几个波数的数量级)的非弹性激发，即“玻色子峰值”，在高温下从准弹性过抑制散射定律中幸存下来。讨论了这一玻色子峰与在T-g附近出现的快速动态过程之间的联系。
Recent neutron scattering experiments on the microscopic dynamics of polymers below and above the glass transition temperature T-g are reviewed. The results presented cover different dynamic processes appearing in glasses: local motions, vibrations, and different relaxation processes such as alpha- and beta-relaxation. For the alpha-relaxation, which occurs above T-g, it is possible to extend the time-temperature superposition principle, which is valid for polymers on a macroscopic scale, to the microscopic time scale. However, this principle is not applicable for temperatures approaching T-g. Below T-g, an inelastic excitation at a frequency of some hundred gigahertz (on the order of several wave numbers), the ''boson peak,'' survives from a quasi-elastic overdamped scattering law at high temperatures. The connection between this boson peak and the fast dynamic process appearing near T-g is discussed.