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Viscosity Measurement and Relaxation Mechanism of Glasses Far Below the Glass Transition Temperature.

远低于玻璃化转变温度的玻璃的粘度测量和松弛机制。

基本信息

批准号：
07455439
负责人：
MATUSITA Kazumasa
金额：
$ 0.7万
依托单位：
Nagaoka University of Technology.
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

It is generally believed that viscous flow never occurs in a glass below glass transition temperature because of rigid state in which atomic or molecular motions are frozen. However, volume shrinkage or crystallization have been observed even below the glass transition temperature.In the present study, we proposed the new method of viscosity measurement far below the transition temperature in the range of 10^<14>-10^<18> Pa・s. The glass fiber of 0.1 mm diameter was wound and kept at temperatures far below the transition range. By measuring the remained curvature radius after the heat treatment as a function of the heat treatment time, the viscosity was determined. The viscosity thus determined is not an intrinsic value since the glass is thermodynamically non-equilibrium state and the properties depend on thermal history. In addition a glass should be treated as a viscoelastic substance.The glass fiber was heated with various temperatures and times before viscosity measurement, and the relaxtion process at low temperature was analyzed based on the non-lonear relaxation function from the viscosity change with heat-treatment. It was found that the apparent viscosity and relaxation time as well as the activation energy for relaxation increase remarkably with heat-treatment. The relaxation spectrum becomes narrow and sharp. In addition, it was tried to separate the contributions of delayd elasticity and viscous flow.

一般认为，在玻璃化转变温度以下的玻璃中永远不会发生粘性流动，因为原子或分子运动处于冻结的刚性状态。然而，即使在玻璃化转变温度以下也会观察到体积收缩或结晶。在本研究中，我们提出了在10^&lt；14&gt；-10^&lt；18&gt；PA·S范围内远低于玻璃化转变温度的粘度测量新方法。通过测量热处理后的残余曲率半径作为热处理时间的函数，确定了粘度。这样确定的粘度不是内在值，因为玻璃是热力学上的非平衡状态，并且其性质取决于热历史。在测量玻璃纤维粘度之前，对玻璃纤维进行不同温度和不同时间的加热，从玻璃纤维在热处理过程中粘度变化的非长程松弛函数出发，分析玻璃纤维在低温下的松弛过程。结果表明，随着热处理时间的增加，表观粘度、松弛时间和松弛活化能显著增加。弛豫谱变得窄而尖锐。此外，还尝试将延迟弹性和粘性流动的贡献分开。