Dielectric loss vs. temperature

Fig. 6 Dielectric loss vs. temperature at different frequencies, as indicated, for two thin films of hyper-branched polyesters of 27 nm and 28 nm...

Fig. 17 Relaxation rate of the dynamic glass transition vs. inverse temperature for different film thicknesses, as indicated. Inlet, dielectric loss vs. temperature at 31 kHz showing the dynamic glass transition of thin PS films for different film thicknesses, as indicated...

Fig. 10. Mechanical and dielectric loss vs. temperature for various epoxy resins and polyethylene.

Figure 8 Relaxation rates vp vs. inverse temperature for the dynamic glass transition of PMPS as obtained by the different techniques , dielectric spectroscopy , thermal spectroscopy , neutron spectroscopy. The data obtained from neutron scattering depend on the momentum transfer 0. In addition to the dynamic glass transition, the relaxation rates for the methyl group rotation for 0=1.8A ( ) are given. The line is a fit of the Arrhenius equation to the data of the methyl group rotation ( A=8.3kJmoL, log(L = 12.5 Hz). The inset gives dielectric loss vs. frequency for PMPS at different temperatures 212.2 K o, 215.2 K ), 219.2 K A, 225.2 K 0, 235.2 K V, 241.2 K +, 257.41 K , 283.1 K. The errors of the measurements are smaller than the size of the symbols. Lines are guides to the eyes.

Fig. 75 Dielectric loss tangent vs temperature for 11 at different frequencies (from [57])...

Figure 5. Dielectric loss e" vs temperature and vs logarithm 10 of frequency for a thin (10 pm) and aligned sample of polymer 3a (see Tab. 1).

The low temperature properties of a dodecane-hexanol-K.oleate w/o microemulsion from 20°C to -190°C were studied vs. increasing water content (C,mass fraction) in the interval 0.021+-0.1+, by Differential Scanning Calorimetry and dielectric analysis (5 Hz-100 MHz). A differentiation between w/o dispersions is obtained depending on whether they possess a "free water" fraction. Polydispersity is evidenced by means of dielectric loss analysis. Hydration processes occurring, at constant surface tension, on the hydrophilic groups of the amphiphiles, at the expenses of the free water fraction of the droplets, are shown to develop "on ageing" of samples exhibiting a time dependent behavior. 

AH (Figure 5) the frequency dependence of e"diel is distinguished by the appearance of an additional loss peak at the end of the KHz region (Figure 2,curve 3-DPS) the dielectric properties of the system vs. temperature are characterized by Double-Peak-Shaped curves with e and e"/e maxima at -15°C and -33. °C respectively (Figure 1-b,DPS curves). 

Figure 14. Relaxation rate of segmental, normal, and confinement-induced mode versus inverse temperature for a thin PIP film of 45 nm and different molecular weights, as indicated. Inset The corresponding raw data, i.e. dielectric loss s" vs. temperature at 96 Hz for the same thickness and same molecular weights.

Advantages of microwave-assisted leaching vs. conventional Soxhlet can be ascribed to the performance of this heating source based on dielectric loss. The heat appears in the bulk of the irradiated material, thus giving rise to an inverse temperature gradient that is, volume rather than surface heating. Thus, both the extraction time and the volume of solvent required are dramatically reduced. " However, the efficiency of microwaves can be very poor when either the target analytes or the solvents are nonpolar or of low polarity, when these are volatile, and when the solvents used have low dielectric constants. In these cases, Soxhlet extraction is superior to MAE. 

Figure 3. Dielectric loss factor, tan 6, vs. temperature for different PP-PC blend compositions at 0.06 KHz.

Figure 8 Arrhenius plots of the logarithm of the frequency of m ocimum loss vs. reciprocal temperature for the dielectric a-relaxations in GE LEXAN 145 PC ( ), VALOX 315 PBT ( ), a 5 4 PC/PBT blend (4) and a 5 4 PC/PBT blend containing 10% impact mMifier ( [adapted from ref 48]...

Figure 4b. Dielectric storage (e ) and loss (e") moduli vs. temperature at different frequencies (1-100 Hz) for the Aied poly(amide-imide) with 0% water.

Figure 3 The dielectric loss tangent of molecular sieve 3A dispersed into the polydimethylsiloxane (PDMS) suspension vs. frequency at different temperature. Reproduced with permission from T. Hao, A. Kawai, and F. Ikazaki, J. Colloid Interface Sci., 239(2001)106...

Figure 2. (a) Complex relative permittivity of Fe203 vs. temperature at 915 and 2450 MFIz. (b) Dielectric loss tangent of Fe2C>3 vs. temperature at 915 and 2450 MHz. 

Fig. 1. Mechanical and dielectric loss tangents, shear modulus G and inverse permittivity (1/e) vs temperature. Test frequency 10-50 Hz -, mechanical —, dielectric, (a),...

Figure 6. Isothermal plots of the dielectric loss component, e , vs. frequency, P, in the merging region for neat PBT and two PBT/PC copolymers (weight ratios indicated in the figure). The solid lines represent the results of fitting experimental data to the sum of two Havriliak-Negamy equations (Eq. 1) -ith a conductivity term. The dashed lines at the highest temperature show the separate contributions of (3 and 7 processes...

The time scale of the DRS a response was further studied by means of Arrhenius plots (activation diagrams). As an example, Figme 8 shows the Arrhenius plot (log vs. reciprocal temperature, where is the frequency of maximum dielectric loss) for two samples, PUl and PU4 of Table 2. The data were fitted to the Vogel-Tammann-Fulcher (VTF) equation [56]... 

Figures 3-5 that the dielectric relaxation again reveals only a single a relaxation for the mixtures. These are, however, noticeably broader than the a relaxation of the pure polymers. The temperatures of the loss maxima, when plotted (Figure 7) as a function of wu the weight fraction of PPO in the mixtures, do not display the smooth monotonic increase in T0 vs. Wi that was shown by both the Vibron and the DSC results. Instead, there is a pronounced increase in Tg above = 0.5 to give a sigmoid curve for this relation. Some reservations should be attached to this observation inasmuch as data for only three polyblend compositions are available nevertheless a qualitatively similar phenomenon is observed in the analysis of the intensity of the y peak (below). Further, if only the stronger maxima in the dynamical mechanical data are considered— i.e.y if the secondary peaks and shoulders which led to the identification of two phases are omitted—then a similar sigmoid curve is found. The significance of this observation is discussed later.

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