Polystyrene dielectric data

Figure 3. Representative dielectric data for polystyrene taken at 100 kHz. Key +, untreated and , exposed to ozone at 375 ppm for 150 min.

Figure 4. Cole-Cole plot of polystyrene at temperature of FkHz glass transition, from dielectric data. Key , untreated at397 K and exposed to ozone at 375ppmfor 75 min at 391K.

Polystyrene can be exceptionally crosslinked, leading to a tough and transparent material with improved electrical and thermal properties used as a dielectric material. Table 4.34 displays examples of crosslinked polystyrene properties. The data cannot be used for designing. 

For thin polystyrene films annealed for 12 hours at 150 °C in high vacuum (10-6 mbar) and measured in a pure nitrogen atmosphere the dynamic glass transition was characterized using two experimental techniques capacitive scanning dilatometry and Broadband Dielectric Spectroscopy. Data from the first method are presented in Fig. 15a, showing the real part of the complex capacity at 1 MHz as a function of temperature for a thin PS film of 33 nm. 

FIGURE 3.18 Frequency dependence of the relative dielectric increment of 265-nm radius polystyrene spheres in 0.1 nunol/1 KCl solution. Symbols experimental data soUd line classical calculation dashed line DSL calculation. In both calculations, the zeta potential used was the one best-fitting simultaneously electrophoretic mobility and dielectric dispersion data. 

Carrique, F., Zurita, L., and Delgado, A.V., Some experimental and theoretical data on the dielectric relaxation in dilute polystyrene suspensions, Acta Polymerica, 45, 115, 1994. 

The consistency of these various methods may be evaluated from the results listed in Table I of data obtained with polystyrene in solvents of low viscosity by the sound absorption (SA) and NMR relaxation methods, for poly(p-chloro-styrene) by dielectric dispersion (DD), for polystyrene labelled with nitroxyl by the ESR method and for a styrene copolymer with a small concentration of 9-p-vinylphenyl-lO-phenylanthracene residues by depolarization of fluorescence (DF). It may be seen that sound absorption and dielectric dispersion yield similar transition frequencies in the range of 12-35 MHz at 10-25 C,... 

In many studies, isochronal measurements have been made at two or more different frequencies and the loci of maxima in the loss tangent mapped against temperature and frequency, often supplemented by dielectric and nuclear magnetic resonance data, as illustrated for polystyrene in Fig. 15-11. Here, five mechanisms... 

Various instrumental methods applied or developed at MMI over the past ten years to study liquid state transitions are presented. T>Tg transition studies with an emf asis on polystyrene are discussed. Instrumental techniques cover the areas of dielectric relaxation, thermal methods, dynamic mechanical relaxation, and computer statistical analysis of tabulated literature data, as well as the spectroscopic methods of Fourier transform infrared and electron spin resonance. 

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