Analysis of the electric relaxation in acrylate polymers with rigid side groups

Abstract

Temperature-domain analysis of primary and secondary dielectric relaxation phenomena in a nonlinear optical side-chain polymer Thermally stimulated depolarization current investigation of the relaxation behavior of polymers with chlorocyclohexyl side groups Order/disorder phase transitions of liquidcrystalline polymers with rigid groups in the side chains. A lattice theoryThe curves describing the temperature dependence of the dielectric loss for poly(4-acryloxyphenyl)-(4-chlorophenyl)-methanone exhibit a well developed subglass absorption followed in order of increasing temperature by an ostensible glass-rubber relaxation or (Y process. Free charge conductivity processes and blocking electrode phenomena become dominant in the a relaxation at frequencies below 10 Hz. An electric model is proposed to interpret the dielectric results covering the glassy state and the glass-rubber transition. The model is basically a parallel configuration involving a condenser (C,J, a resistance (R), and a Havriliak-Negami-type impedance (Z&J coupled in series with an impedance (Zz) representing the electrode phenomena. The circuit allows one to split the dipolar processes from both free charges and blocking electrode conductivity contributions to the real d and loss C' parts of the complex dielectric permittivity at temperatures above the glass transition temperature of the polymer. At low frequencies the model predicts that d and 6 scale with frequency as E' -u-('+~) and E" -w-', the exponent 5 not being restricted to the conventional value of 0.5 commonly found in the literature.

Modeling of X‐ray‐Induced Refractive Index Changes in Poly(methyl methacrylate)

“…It is interesting to note that in the dielectric spectrum the α relaxation cannot be easily observed due to continuous increase of the loss factor. This phenomenon suggests that the conductivity contributions (combination of the bulk conduction and interfacial polarizations effects31) are dominant in the dielectric response 21, 32, 33. It should be taken into account that bulk conductivity does not include only ohmic conductivity but can also be originated by other mechanisms, mainly ionic conductivity although non‐ohmic electronic mechanisms (hopping conductivity, for example) could also be present.…”

Relaxational Study of Poly(2-chlorocyclohexyl methacrylate) by Thermally Stimulated Current, Dielectric, and Dynamic Mechanical Spectroscopy

“…In this case, it is interesting to note that the α relaxation cannot be easily observed due to the continuous increasing of the loss permittivity. This phenomenon, involving a continuous increasing of the loss permittivity when the temperature rises, suggests that the conductivity contributions (combination of the bulk conduction and interfacial polarizations effects) are dominant in the dielectric response. , When the electric modulus formalism is used for the representation of the data, it could be possible to gain confidence about this fact, because a better visualization of both effects is obtained. The electric modulus is defined as and consequently where M ‘ and M ‘ ‘ are the storage and loss dielectric modulus, respectively.…”

Influence of the Metal Cross-Linking on the Dielectric, Mechanical, and Thermal Properties of a Liquid Crystalline Polyazomethine

“…In order to study this conductivity process, we have analyzed the data in the framework of an electrical model recently reported in the literature. 22 The application of this model led us to consider that our process is associated with a bulk process rather than an interfacial one. Taking into account the thermal behavior exhibited by the samples, two phenomena might be involved in this process.…”