Alternating-current (ac) conductivity and dielectric relaxation behaviour of a poly(vinyl chloride)/poly(ethyl methacrylate) polymer blend have been investigated intensively in a frequency range from 1 × 10 −1 to 2 × 10 7 Hz through a temperature range from 300 to 393 K. The variation of σ ac of pure and polyblend samples showed a plateau region at high temperature and low frequency and this plateau region is decreased with decreasing temperature. Values of the exponent n are less than unity indicative of the correlated barrier hopping for conduction. The values of the exponent n are used to calculate the binding energy (W m) of the charge carriers. The investigation of the frequency dependence of ε for pure and polyblend samples showed a dielectric dispersion. The high values of dielectric constant at a low frequency and high temperature are attributed to the effects of space charge due to the electrode polarization. The complex electric modulus (M*) of pure and polyblend samples has been investigated. It is found that the real part of the complex electric modulus, M is increased non-linearly as the frequency increased and reached the steady state at higher frequencies for all samples. On the other hand, the imaginary part of the complex electric modulus, M is characterized by a relaxation peak. The different modes of relaxation, such as interfacial polarization and dipolar relaxation, are detected in low and high frequency regions in the variation plot of M against frequency. The activation energy values of both interfacial polarization and α-relaxation are calculated.
In this study, the electro-chemical behavior of Udimet700 alloys is studied in acidic media at 25°C. It deals with the corrosion inhibition process of nickel–based (Udimet700) alloy in 1M–HCl solution by some organic derivatives. The methods used include electro–chemical frequency modulation technique, electro–chemical impedance spectroscopy, and potentio–dynamic polarization. The derivatives are considered as mixed–type inhibitor depending on potentio–dynamic polarization analysis. Scanning electron microscope examination is executed to study the morphology of Udimet700 surface after immersion in a solution in the case of presence and absence of derivatives. The results of this research reveal that the inhibitors are absorbed by Udimet700 alloy surface and they insulate it from the acidic medium. The compound (C16H17) among the tested organic derivatives plays the best role as an inhibitor of the alloy in 1M–HCl.
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