ZetaTrainingsc资料讲解.ppt

Besides true solutions of both macromolecular materials such as synthetic polymers, and biomolecules and some molecular associations like liposomes or micelles, that are thermodynamically stable and reversible, most particle systems are thermodynamically unstable and irreversible after phase separation due to their high surface free energy. We call these systems dispersions. In the above matrix, the first line in each box is the common terminology used to describe that system, with some common examples included below. For particle characterization, most attention and interest are in the dispersions of particles in liquids and in gases (the two columns on the right in the above matrix). Because liquid aerosol systems are usually associated with flow and liquid aerosols are almost always round in shape, a different set of techniques is employed for liquid aerosols, such as phase Doppler analysis, which is beyond the scope of this text. We will focus our discussion on the systems in the gray boxes in the above matrix. The one idea to remember about zeta potential, is that it is not the same parameter as surface charge or surface potential. This difference may not be very important for simple systems such as a dispersed mineral oxide in demineralised water, but as soon as there are other components in the dispersion that interact with the surface. These components can change the magnitude of the zeta potential or even reverse the sign of the charge. The zeta potential is the value of the potential at a distance from the surface known as the slipping plane. This is the distance within which the ions move as part of the particle, and from the charge point of view defines the particle. Particles interact according to the magnitude of the zeta potential not their surface change. * Zeta电位测量的分辨率:极小范围 频率位移0.01 Hz, 0.005Hz, 0.002Hz 相分析图 用富里埃分析得到的频率位移0.01 Hz, 0.005Hz, 0.002Hz电位图 Zeta电位测量的方波形,快转与慢转的组合 电流与电压波型重叠 注意极灵敏度的电流测量-分辨率达到2微安 相位图 FFR PALS only to obtain mean (Ep) SFR PALS