电镜中相位衬度原理及对高聚物样品衬度的改善

PHASE CONTRAST PRINCIPLES IN TEM AND ITS APPLICATIONS IN CONTRAST IMPROVEMENT OF POLYMERS SPECIMENS

本文讨论了电镜中相位衬度成象原理以及在高聚物结构形态观察中的相位(离焦)衬度技术。由于相位(离焦)衬度不受外来染色原子二次效应的干扰,可以在不经特别处理情况下对高聚物结构直接进行观察,因此在半结晶高聚物、多相高聚物和聚合物共混形态结构研究中,特别是高聚物动力学过程的研究中得到了有效的应用。

A significant problem in studies of polymer morphology by TEM is obtaining sufficient contrast in electron micrographs to visualize the structures When diffraction contrast can be used, or if a specific heavy atom stain is available, unambiguous interpretation is generelly possible. If these techniques cannot be emplyed, phase (defocus) contrast is the only source of contrast available. In this paper the phase contrast principles and defocus-contrast technique for studies of polymer morphology is discussed. This method unexists secondary effects which are not dependent directly on the structure of the polymer but on properties which are staining heavy atoms structure-dependent. The specimen requires no specical preparation; it can be observed directly under the desired conditions. A further advantage of phase contrast is the possibility of following a dynamic process, such as lamelar grawth. Results are reported concerning lamelar crystallization and lamelar thickening during annealing, in addition to several general applications of the technique.