scholarly journals Molecular Dynamics of Functional Azide-Containing Acrylic Films

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 859 ◽  
Author(s):  
Marta Carsí ◽  
Maria Sanchis ◽  
Saul Vallejos ◽  
Félix García ◽  
José García
Keyword(s):  
General Structure ◽  
Glassy State ◽  
Interfacial Polarization ◽  
Dielectric Analysis ◽  
Azide Group ◽  
Low Frequencies ◽  
Polarization Effects ◽  
Dynamic Mobility ◽  
Models Comparison ◽  
Ohmic Conductivity

A report on the syntheses, thermal, mechanical and dielectric characterizations of two novel polymeric acrylic materials with azide groups in their pendant structures is presented. Having the same general structure, these polymers differ in length of oxyethylene units in the pendant chain [-CONH-CH2CH2-(O-CH2CH2)nN3], where n is 1 (poly(N-(2-(2-azidoethoxy)ethyl)methacrylamide), PAzMa1) or 2 (poly(N-2-(2-(2-azidoethoxy)ethoxy)ethyl)methacrylamide), PAzMa2), leading with changes in their dynamics. As the thermal decomposition of the azide group is observed above 100 °C, dielectric analysis was carried out in the temperature range of −120 °C to 100 °C. Dielectric spectra of both polymers exhibit in the glassy state two relaxations labelled in increasing order of temperature as γ- and β-processes, respectively. At high temperatures and low frequencies, the spectra are dominated by ohmic conductivity and interfacial polarization effects. Both, dipolar and conductive processes were characterized by using different models. Comparison of the dielectric activity obtained for PAzMa1 and PAzMa2 with those reported for crosslinked poly(2-ethoxyethylmethacrylate) (CEOEMA) was performed. The analysis of the length of oxyethylene pendant chain and the effect of the methacrylate or methacrylamide nature on the dynamic mobility was analysed.

Interfacial polarization effects on dielectric properties in flax reinforced polypropylene/strontium titanate composites

2021 ◽  
pp. 124489
Author(s):  
P.V.S. Hari Prashanth ◽  
Elammaran Jayamani ◽  
Kok Heng Soon ◽  
Yat Choy Wong ◽  
Mohammed Rezaur Rahman ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Strontium Titanate ◽  
Interfacial Polarization ◽  
Polarization Effects

Electrical conductivity and dielectric relaxation studies of biocomposites based on green microcrystalline cellulose-reinforced vinyl resin matrix

2019 ◽  
Vol 53 (20) ◽  
pp. 2801-2808 ◽  
Author(s):  
L Kreit ◽  
I Bouknaitir ◽  
A Zyane ◽  
M El Hasnaoui ◽  
M E Achour ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Glass Transition ◽  
Microcrystalline Cellulose ◽  
Interfacial Polarization ◽  
Relaxation Frequency ◽  
Resin Matrix ◽  
Matrix Interface ◽  
Frequency Range ◽  
Low Frequencies ◽  
Dielectric Relaxations

The dielectric properties of biocomposite materials based on vinyl resin filled with microcrystalline cellulose, in the frequency range from 100 Hz to 1 MHz and in the temperature range from 280 to 400 K, are presented. Two dielectric relaxations were identified. The first one is attributed to the α-relaxation, associated with the glass transition of biocomposite, and the second one, appearing above the glass transition and at low frequencies, was identified as the interfacial polarization effect, which is attributed to the accumulation of charges at the cellulose microcrystalline/matrix interface. Furthermore, the thermal analysis of their relaxation frequency and the electrical conductivity behaviors showed that the activation energy of these composite is more pronounced for the temperatures above the glass transition temperature, suggesting that the interaction between MCC particles and polymeric matrix became significant with the increase of temperature.

scholarly journals Polyaniline/Polystyrene Blends: In-Depth Analysis of the Effect of Sulfonic Acid Dopant Concentration on AC Conductivity Using Broadband Dielectric Spectroscopy

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Noora Al-Thani ◽  
Mohammad K. Hassan ◽  
Jolly Bhadra
Keyword(s):  
Dielectric Spectroscopy ◽  
Ac Conductivity ◽  
Sulfonic Acid ◽  
Low Frequency ◽  
Lone Pair ◽  
Interfacial Polarization ◽  
Low Frequencies ◽  
Broadband Dielectric Spectroscopy ◽  
Wide Range ◽  
Depth Analysis

This work presents an in-depth analysis of the alternating current (AC) conductivity of polyaniline-polystyrene (PANI-PS) blends doped with camphor sulfonic acid (CSA) and prepared using an in situ dispersion polymerization technique. We prepared the blends using fixed ratios of PS to PANI while varying the concentration of the CSA dopant. The AC conductivity of the blends was investigated using broadband dielectric spectroscopy. Increasing CSA resulted in a decrease in the AC conductivity of the blends. This behaviour was explained in terms of the availability of a lone pair of electrons of the NH groups in the polyaniline, which are typically attacked by the electron-withdrawing sulfonic acid groups of CSA. The conductivity is discussed in terms of changes in the dielectric permittivity storage (ε′), loss (ε′′), and modulus (M′′) of the blends over a wide range of temperatures. This is linked to the glass transition temperature of the PANI. Dielectric spectra at low frequencies indicated the presence of pronounced Maxwell-Wagner-Sillars (MWS) interfacial polarization, especially in samples with a low concentration of CSA. Electrical conduction activation energies for the blends were also calculated using the temperature dependence of the direct current (DC) conductivity at a low frequency (σdc), which exhibit an Arrhenius behaviour with respect to temperature. Scanning electron microscopy revealed a fibrous morphology for the pure PANI, while the blends showed agglomeration with increasing CSA concentrations.

scholarly journals Application Properties Analysis as a Dielectric Capacitor of End-of-Life Tire-Reinforced HDPE

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2675 ◽  
Author(s):  
Marc Marín-Genescà ◽  
Jordi García-Amorós ◽  
Ramon Mujal-Rosas ◽  
Lluís Massagués Vidal ◽  
Xavier Colom Fajula
Keyword(s):  
Carbon Black ◽  
End Of Life ◽  
Polymeric Composite ◽  
Interfacial Polarization ◽  
Morphological Properties ◽  
Electrical Behavior ◽  
Scanning Calorimetry ◽  
Low Frequencies ◽  
Vulcanized Rubber ◽  
Different Temperatures

The purpose of the present research is to obtain waste of polymeric composite as an insulator capacitive application. Rubber materials, once they end their useful life, may be difficult to reuse or recycle. At present, research only uses one tire recycling method, which involves grinding and separating steel and fibers from vulcanized rubber, and then using the rubber particles for industrial capacitors. The methodology for this research is to compare the permittivity (ε′ and ε″) between high-density polyethylene (HDPE) and the polymer matrix compound, consisting of an HDPE polymeric matrix blended with end-of-life tire particles (ground tire rubber (GTR)), to analyze the feasibility of using such tires as electrically insulating materials (dielectrics). The incorporation of carbon black in the GTR compounds modifies conductivity; GTRs carry a significant amount of carbon black, and therefore some electrical properties may change significantly compared to highly insulating polymer substrates. The performed experimental study is based on a dynamic electric analysis (DEA) test developed in the frequency range of 10−2 Hz to 3 MHz and at different temperatures (from 35 to 70 °C) of different samples type: HDPE neat and HDPE compounds with 10%, 20% and 40% of GTR loads. A sample’s electrical behavior is checked for its dependence on frequency and temperature, focused on the permittivity property; this is a key property for capacitive insulators and is key for examining the possible applications in this field, for HDPE + GTR blends. Results for the permittivity behavior and the loss factor show different electrical behavior. For a neat HDPE sample, no dependence with frequency nor temperature is shown. However, with the addition of 10%, 20%, and 40% amount of GTR the HDPE compounds show different behaviors: for low frequencies, interfacial polarization relaxation is seen, due to the Maxwell–Wagner–Sillars (MWS) effect, performed in heterogeneous materials. In order to analyze thermal and morphological properties the differential scanning calorimetry (DSC) test and scanning electron microscopy (SEM) have been used. Results obtained show that adding waste tire particles in an HDPE matrix allows HDPE + 40% GTR blends to act as a dielectric in capacitors, increasing the capacitor dielectric efficiency in the low frequencies due to the MWS effect, which increases the dielectric constant.

scholarly journals DIELECTRIC BEHAVIOUR, COMPLEX IMPEDANCE SPECTROSCOPY AND MAGNETOELECTRIC EFFECT IN LSMO-BT COMPOSITES

2012 ◽  
Vol 06 ◽  
pp. 184-190
Author(s):  
S. S. VEER ◽  
S. V. KULKARNI ◽  
S. D. CHAKANE ◽  
P. B. JOSHI
Keyword(s):  
Impedance Spectroscopy ◽  
Magnetoelectric Effect ◽  
Sintering Temperature ◽  
Complex Impedance ◽  
Interfacial Polarization ◽  
Dielectric Behaviour ◽  
Complex Impedance Spectroscopy ◽  
Low Frequencies ◽  
Sintering Aid ◽  
Co Precipitation

The paper deals with Dielectric Behaviour, Complex Impedance Spectroscopy and Magnetoelectric effect in La 0.7 Sr 0.3 MnO 3(LSMO) and BaTiO 3 (BT) Composites. The LSMO and BT are synthesized by hydroxide co-precipitation route. The nanocomposites are prepared by two series x LSMO + (1-x) BT + 2 wt % Bi 2 O 3, for x = 0.05, 0.1, 0.15 and 0.2 ……series 1. x LSMO + (1-x) BT + 3 wt % Bi 2 O 3, for x = 0.05, 0.1, 0.15 and 0.2 ……series 2. and sintered at Ts=1000°C and 1080°C. The composites are termed as LSMO - BT . The paper reports the crystal structure, micro-structural analysis, dielectric constant, complex impedance spectroscopy and magnetoelectric properties of LSMO - BT composites. It has been observed that the ε r passes through a broad maximum at T ~ 124° C, which is nearly the ferroelectric transition temperature of BT . Both ε r and ε rmax increases as x increases from 0.05 to 0.2. The ε r ' and ε r '' decreases sharply for all the compositions at low frequencies. This feature is typical of the presence of interfacial polarization. The variation of 4πMs is almost linear with x , the 4πMs increases with x as well as sintering aid. The 4πMs of respective compositions reduce as the sintering temperature is increased. The value of α increases for increase in sintering temperature as well as increase in wt % of the sintering aid. The magnitude of α is in the range as reported earlier for composites based on BT .

scholarly journals Dielectric Response during Cure of Particulate Composites of Epoxy Resin and Nickel Particles

1995 ◽  
Vol 4 (3) ◽  
pp. 096369359500400
Author(s):  
G.M Tsangaris ◽  
G.M. Maistros
Keyword(s):  
Epoxy Resin ◽  
Metal Powder ◽  
Dielectric Response ◽  
Interfacial Polarization ◽  
Metal Particles ◽  
Particulate Composites ◽  
Cure Process ◽  
Low Frequencies ◽  
Nickel Particles ◽  
Polarization Phenomena

The cure process of particulate composites consisting of an epoxy resin and nickel particles, was monitored dielectrically. The inclusion of metal powder in the resin causes a delay in the cure process. It also adds considerable conductivity and after gelation interfacial polarization phenomena are evidenced in the low frequencies, because of the interfaces introduced by the metal particles.

Dynamics of uncharged colloidal inclusions in polyelectrolyte hydrogels

2011 ◽  
Vol 669 ◽  
pp. 298-327 ◽  
Author(s):  
ALIASGHAR MOHAMMADI ◽  
REGHAN J. HILL
Keyword(s):  
Ionic Strength ◽  
Electric Field ◽  
Reference Frame ◽  
Particle Surface ◽  
Fixed Charge ◽  
Particle Displacement ◽  
Restoring Force ◽  
Low Frequencies ◽  
High Frequencies ◽  
Dynamic Mobility

We calculate the dynamics of an uncharged colloidal sphere embedded in a quenched polyelectrolyte hydrogel to (i) an oscillatory (optical and magnetic) force, as adopted in classical micro-rheology, and (ii) an oscillatory electric field, as adopted in electrical micro-rheology and electro-acoustics. The hydrogel is modelled as a linearly elastic porous medium with the charge fixed to the skeleton and saturated with a Newtonian electrolyte; and the colloidal inclusion is modelled as a rigid, impenetrable sphere. The dynamic micro-rheological susceptibility, defined as the ratio of the particle displacement to the strength of an applied oscillatory force, depends on the fixed-charge density and ionic strength and is bounded by the limits for incompressible and uncharged, compressible skeletons. Nevertheless, the influences of fixed charge and ionic strength vanish at frequencies above the reciprocal draining time, where the polymer and the electrolyte hydrodynamically couple as a single incompressible phase. Generally, the effects of fixed charge and ionic strength are small compared with, for example, the influences of polymer slip at the particle surface. The electrical susceptibility, defined as the ratio of the particle displacement to the strength of an applied oscillatory electric field, is directly influenced by charge at all frequencies, irrespective of skeleton compressibility. At low frequencies, polymer charge modulates the driving (electro-osmotic) and restoring (electrostatically enhanced elastic) forces, whereas charge has no influence on the restoring force at high frequencies where dilational strain is suppressed by hydrodynamic coupling with the electrolyte. In striking contrast to charged inclusions in uncharged hydrogels (Wang & Hill, J. Fluid Mech., vol. 640, 2009, pp. 357–400), the electrical susceptibility at high frequencies is independent of electrolyte concentration. Rather, the dynamics primarily reflect the elastic modulus, charge and hydrodynamic permeability, with a relatively weak dependence on particle size. Interestingly, the dynamic mobility in the zero-momentum reference frame, which is central to the electro-acoustic response, is qualitatively different from the dynamic mobility in the skeleton-fixed reference frame. Finally, we propose a phenomenological harmonic-oscillator model to address – in an approximate manner – the dynamics of charged particles in charged hydrogels. This shows that particle dynamics at low frequencies are dominated by particle charge, whereas high-frequency dynamics are dominated by hydrogel charge.

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