Effects of Temperature and Pressure on the Dielectric Constant in Non-Polar Polymers

Sasabe, Hiroyuki; Saito, Shōgo

doi:10.1295/polymj.3.749

Cited by 17 publications

(10 citation statements)

References 9 publications

(2 reference statements)

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“…The latter involves molecular rearrangements that are largely frozen out in the glassy state. Although diffusion of ions is usually coupled to rotations of the host molecules, on approach to the glass transition the proportionality of the respective time constants is lost, with the former enhanced relative to the reorientational motions [2][3][4][5][6][7][8]. In this work, we show the further disconnect between the two dynamics as the glass transition is traversed.…”

mentioning

confidence: 61%

Anomalous Electrical Conductivity Behavior at Elevated Pressure in the Protic Ionic Liquid Procainamide Hydrochloride

et al. 2012

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Using broadband dielectric spectroscopy, we investigated the effect of hydrostatic pressure on the conductivity relaxation time τ{σ} of the supercooled protic ionic liquid, procainamide hydrochloride, a common pharmaceutical. The pressure dependence of τ{σ} exhibited anomalous behavior in the vicinity of the glass transition T{g}, manifested by abrupt changes in activation volume. This peculiar behavior, paralleling the change in temperature dependence of τ{σ} near T{g}, is a manifestation of the decoupling between electrical conductivity and structural relaxation. Although the latter effectively ceases in the glassy state, free ions retain their mobility but with a reduced sensitivity to thermodynamic changes. This is the first observation of decoupling of ion migration from structural relaxation in a glassy conductor by isothermal densification.

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mentioning

confidence: 61%

Anomalous Electrical Conductivity Behavior at Elevated Pressure in the Protic Ionic Liquid Procainamide Hydrochloride

et al. 2012

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“…In this context, one should note that, e.g., the dielectric constant ε = ε(p, T) depends on both temperature and pressure, complicating the issue considerably; for small ranges of temperature and pressure, ε(p, T) commonly changes with temperature and pressure in an approximately linear fashion in a solid [32,33]…”

Section: Aspects Of the Hydrogen Atom-like Systemmentioning

confidence: 99%

“…In this context, one should note that, e.g., the dielectric constant

depends on both temperature and pressure, complicating the issue considerably; for small ranges of temperature and pressure,

commonly changes with temperature and pressure in an approximately linear fashion in a solid [ 32 , 33 ], i.e.,

. Depending on the type of system, we may have

and

, respectively [ 32 ], or the opposite [ 33 ], or other combinations. Thus, e.g., we find that

increases with pressure and decreases with temperature for CdF 2 [ 32 ], and we could translate our analysis from using

as control variables, in principle.…”

Section: Introductionmentioning

confidence: 99%

Optimal Control of Hydrogen Atom-Like Systems as Thermodynamic Engines in Finite Time

Schön

2020

Entropy

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Nano-size machines are moving from only being topics of basic research to becoming elements in the toolbox of engineers, and thus the issue of optimally controlling their work cycles becomes important. Here, we investigate hydrogen atom-like systems as working fluids in thermodynamic engines and their optimal control in minimizing entropy or excess heat production in finite-time processes. The electronic properties of the hydrogen atom-like system are controlled by a parameter reflecting changes in, e.g., the effective dielectric constant of the medium where the system is embedded. Several thermodynamic cycles consisting of combinations of iso-, isothermal, and adiabatic branches are studied, and a possible a-thermal cycle is discussed. Solving the optimal control problem, we show that the minimal thermodynamic length criterion of optimality for finite-time processes also applies to these cycles for general statistical mechanical systems that can be controlled by a parameter , and we derive an appropriate metric in probability distribution space. We show how the general formulas we have obtained for the thermodynamic length are simplified for the case of the hydrogen atom-like system, and compute the optimal distribution of process times for a two-state approximation of the hydrogen atom-like system.

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“…According to the Clausius‐Mosotti (C‐M) equation of dielectric polarization

P_{m} = \frac{ɛ - 1}{ɛ + 2} \times \frac{M}{ρ} = \frac{N_{A}}{3 ɛ_{0}} \times (α_{e} + α_{a} + α_{d})

where

P_{m}

is the polarization,

M

is the relative molecular weight,

ρ

is the density of the material, and

N_{A}

is the Avogadro's constant.…”

Section: Theoretical Analysismentioning

confidence: 99%

“…In the process of SBR's thermo-oxidative aging, a e barely changes from the external electric field which is much weaker than the electric field of the nucleus, so this part of the polarizability hardly changes in the THz field; a a is mainly caused by the deformation and twist of the atoms on the molecular-chain skeleton structure; a d is dependent on the fixed dipole moment and the polarity element. According to the Clausius-Mosotti (C-M) equation of dielectric polarization 36,37…”

Section: T Heor Eti Ca L Ana Lys I Smentioning

confidence: 99%

Evolution of terahertz dielectric permittivity of rubber during thermo‐oxidative aging

Chang

Zhang

Cui

2017

Micro & Optical Tech Letters

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Polymer materials such as rubber and plastics are prone to aging induced degradation, especially thermo-oxidative aging. In this paper, terahertz time-domain spectroscopy was employed to investigate the aging process of styrene butadiene rubber by spectrally following the evolution of its dielectric permittivity in the terahertz frequency region during prolonged high-temperature, accelerated, continuous thermo-oxidative aging. The real and imaginary parts of the dielectric constant in the 0.1-0.8 THz frequency band were obtained and analyzed, and shown to be consistent with present theoretical understanding. The study revealed a close relationship between the evolution of the rubber's dielectric permittivity and the material's physical response to the terahertz electromagnetic radiation during thermo-oxidative aging, manifesting a strong correlation between quantitative changes of the dielectric permittivity and the degree of aging, which can be understood qualitatively in terms of dynamical structural changes at the molecular level. K E Y W O R D Sterahertz, rubber, thermo-oxidative aging, dielectric permittivity | I NT RODU CTI ONThe polymer material styrene butadiene rubber (SBR), also known as polystyrene-butadiene copolymer, is currently the most popular man-made commercial rubber, accounting for more than 40% of sales, among all synthetic rubber materials, including butadiene rubber, styrene-butadiene rubber, isoprene rubber, and many others. 1 SBR resembles closely natural rubber, possessing many advantageous properties, such as wear-resistance and heat-resistance, higher curing rate compared with natural rubber, and good compatibility with natural rubbers and various synthetic rubbers. 2 As such it is widely used in aerospace, electronics, and automotive industries, as well as in consumer products such as appliances, apparel, and sporting goods, among many others. [3][4][5] Rubber is apt to suffer from aging due to high temperature, illumination, oxidation, hydrolysis, biodegradation, salt spray, and other environmental factors, 6,7 which degrades its quality and characteristic over time, and shortens its useful lifetime. Although aging of rubber is a natural phenomenon which is ultimately unavoidable, the prevention and retardation of aging, and proactive life prediction of rubber have been active research topics for many years. [8][9][10][11][12][13][14][15][16] Owing to its plastic nature, there are inherently flaws in the molecular structure of rubber, making it easily susceptible to aging due to invasion of external oxygen atoms. SBR's macromolecular chain has a type of unsaturated double bond structure, which readily reacts with oxygen atoms under common ambient conditions. The whole process has three phases, including chain initiation, chain propagation, and chain termination, with the stable product of degradation and crosslink formed at last. Currently, among the detection technologies for prediction of rubber aging, online spectral inspection approaches are the most popular, including i...

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Effects of Temperature and Pressure on the Dielectric Constant in Non-Polar Polymers

Cited by 17 publications

References 9 publications

Anomalous Electrical Conductivity Behavior at Elevated Pressure in the Protic Ionic Liquid Procainamide Hydrochloride

Anomalous Electrical Conductivity Behavior at Elevated Pressure in the Protic Ionic Liquid Procainamide Hydrochloride

Optimal Control of Hydrogen Atom-Like Systems as Thermodynamic Engines in Finite Time

Evolution of terahertz dielectric permittivity of rubber during thermo‐oxidative aging

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