Triboelectric series

Triboelectric Series. Prediction of triboelectric behavior in granular solids is hampered by difficult-to-control factors such as particle shape, prior mechanical contacts, material purity, and particle moisture content (which is usually related to airborne humidity). In the absence of any reliable predictive model for powder electrification, the practical requirements of industry necessitate an empirical approach (Taylor and Seeker,... 

Typical Triboelectric Series (Most Positive at Top of List)... 

Figure 2.39 Triboelectric series and selected pigments used in commercial toners.

Since electric charges may be transferred by rubbing surfaces of nonconductors against each other, the ancients were able to develop a crude triboelectric series based on amber, glass, and other available nonconductors. 

The electrostatic charge on the polymer depends on both the polymer, the material used as the rubber, and the time of rubbing. Test methods for triboelectric properties have been standardized, and triboelectric series for polymers are available. 

FIGURE 8.1 Triboelectric series of materials. Cotton is used as the neutral or reference material. Tribo-negative materials contain free negative charges, and tribo-positive materials contain free positive charges. These charges are easily transferred to other materials that they might contact. 

In facilities that handle or manufacture sensitive electronic devices, static control is a primary concern. The two important aspects of static control are control of static on personnel and control of static in the facility. Both these issues are part of a composite static control strategy. Static control in personnel starts with attention to the clothing and shoes worn by people working in the environment. Use of cotton clothing is essential, as cotton is neutral in the triboelectric series. Leather-soled shoes are preferred to shoes with composite or crepe soles. Shoe straps made of semiconductive material can be wrapped around a person s ankles and attached to... 

Strella (1970, 1971) based his triboelectric series on contact potential differences. Table 11.5 shows a reproduction of it. 

The possibility of ranking polymers in a self-consistent way for the purposes of predicting the relative direction of charge transfer when any two of them are allowed to make contact with each other has been recognised for a long time, and many so-called triboelectric series, obtained in an empirical way, have been published. The physical basis for such series is now evident. 

The peak current and the total area under the curve for the contact current and for the separation eurrent are nearly identical, differing only in the sign. From the contact and separation current value a triboelectric series, which shows not only the position but also quantitative separation between two positions, is constructed as shown in Table 24.1. Triboelectric series based on the average current on contact and separation is given in Table 24.2, in which the zero point is set at nylon. 

Table 24.2 Triboelectric Series Based on Contact Electrification/Separation Current...

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