TSD current

Fig. 10, TSD current at TTj = —148 °C as a function of network unreacted epoxygroup concentration...

TSD currents of SSBR rubber systems as a function of the temperature... 

The principal characteristics of the triboelectret state in polymers recorded experimentally are i) the efficient surface charge density (ESCD) value and ii) the thermally stimulated depolarization (TSD) current spectrum, i.e. the discharge current dependence of the electret on its heating temperature. The analysis of TSD spectra helped to estimate the parameters of the triboelectret state, including the homo- to heterocharge relation in a dielectric, activation energy of the charge relaxation processes, relaxation time and others. 

The TSD current spectra of triboelectrets of polar as well as nonpolar polymers show three peaks (Table 4.3). PE peak II is attributed to relaxation of the residual polarization as a result of accumulation and orientation... 

Eriction Temperature ESCD, Temperature of Activation energy Velocity, in the Friction 10 TSD Current for TSD Current... 

Thermally stimulated depolarization (TSD) current was also measured using an Ekco type 616B electrometer. The samples were polarized at the following conditions polarization temperature 150 0, polarization time 2 min, electric field 8 kV/cm. The heating rate was 1°C/min. 

The results of measurements of TSD current are shown in Figs. 6 to 8. Maxima at about 65 and 120 C were observed in the measured temperature range for PP component and at about 150 C for PC component (Fig. 6). The maxima for PP can be connected with the release of free charge carriers from their traps, depending on the polymer... 

TSD current for PP-PC blends depends, above all, on the PC content, and two maxima of current intensity are observed the higher intensity maximum at about 150 C attributed to Tg of PC, and the lower one above 150 C, This second maximum can reflect an effect of free charge relaxation which could be connected with the presence of PP in the blends and attributed to the melting temperature of PP. The maximum at 65°C, typical of pure PP, is not observed for PP-PC blends. 

Figure 7. TSD current vs. temperature for different PP-PC blend compositions.

Maxima of TSD current, attributed to Tg of PC, Tge vs. the composition of PP-PC blends, are shown in Fig. 8. The dynamic glass transition temperature, Tg, from measurements of mechanical properties is also ahown in Fig. 8 for the sake of comparison. It is... 

Figure 8. Maxima of TSD current, Tg, and dynamic glass transition temperature Tg, vs. PP-PC blend composition.

Measurements of tan 6 and TSD current indicate that there are some characteristic interactions for the PP-PC blend with 90 wt.% PC and the increase of average dipole moment of polar groups is the highest in this case. Some chain orientation of PC macromolecules, induced by the presence of semi-crystalline PP component, can be one of the reasons of such an increase. This assumption, however, was not fully confirmed by x-ray measurements of crystallinity and by electron scanning microscopy of PP-PC blends... 

The tablets (diameter 30 mm, thickness 1 mm) with the frozen aqueous suspension of silicas (16.7 wt%, i.e., h=5 mL/g) were polarized by the electrostatic field at the intensity =200-300 kV/m at 260 K then cooled to 90 K with the field still applied and heated without the field at a heating rate P = 0.05 K/s. The current evolving due to sample depolarization was recorded by an electrometer over the 10 -10 A range. Relative mean errors for measured TSD current were 5% for the current, 2 K for temperature, and 5% for the temperature change rate. Modified GT equation with... 

FIGURE 5.45 (a) Temperature dependence of the TSD current for the initial collagen hydrogel and free ... 

FIGURE 7.57 (a) TSDC spectra of individual water and water located in rat tail vertebrae initially and after additional adsorption of water vapor for 24 h (+6 wt%) (discharging current has the opposite sign to that of the TSD current) and (b) pore size distribution calculated on the basis of the TSDC for initial bone tissue (sample I) for dipolar relaxation at 7 <225 K. (Adapted from Colloids Surf. B Biointerfaces, 48, Turov, V.V., Gun ko, V.M., Zarko, V.I. et al.. Weakly and strongly associated nonfreezable water bound in bones, 167-175, 2006a, Copyright 2006, with permission from Elsevier.)... 

FIGURE 9.3 Temperature dependences of TSD current and amount of unfrozen water, ( H NMR) for yeast cells initial dry containing 7 wt% of water (curves 1 and 4) and hydrated at 50 (curve 2), 52 (curve 5), and 75 (curve 3) wt% of bound water. 

The presence of stearate surface treatment [6] or other surfactants [7] leads to the appearance of new depolarization peaks and increases the TSP and TSD currents. Adsorbed water causes further complications in the TSP curves, as it is gradually desorbed between 30 and 80°C. Some representative TSD curves of filled PP composites are collected in Figure 3. 

Fig. 6 Charge TSD and TSD current spectra of parylene HT samples without annealing solid) and annealed at 400 °C for 1 h before charging dashed). The surface potentials are normalized to the initial values, and the TSD current is shown in an arbitrary unit (Lo and Tai 2008)...

The two contributions to the charging cunent behave differently as functions of temperature. The orientation of the dipoles is a transient process giving rise to a peak, whereas the conduction current, which derives from the motion of equilibrium caniers, increases steadily with temperature. The conduction current appears at a higher temperature than the dipole orientation curreoL In the temperature range of low conductioo, the TSP and TSD currents are equal, but when the temperature eventually becomes hi the conduction current dominates in TSP. 

FIgura 38 Effect of electrode material on TSD current spectra of PTUFA. (From Ret 2S.)... 

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