Thermally stimulated depolarization currents in poly(vinyl alcohol) films

Rao, Vijayalakshmi; and, K. Jeevana Krishna; Rao, B. Srinivasa

doi:10.1002/actp.1992.010430202

Cited by 4 publications

(1 citation statement)

References 10 publications

(4 reference statements)

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“…For this purpose, 2‐acrylamidoglycolic acid has been chosen as a monomer, which is also hydrophilic in nature . The 2‐acrylamidoglycolic acid refers to a class of acrylamides containing OH, COOH, and CONH functional groups that shows excellent selectivity in separating apatite from siliceous gangue . A number of copolymers have also been recognized to have ability to respond to several stimuli and to recover metal ions .…”

Section: Introductionmentioning

confidence: 99%

Radiation initiated synthesis of 2‐acrylamidoglycolic acid grafted carboxymethyl cellulose as pH‐sensitive hydrogel

El‐Mohdy

2013

Polymer Engineering & Sci

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This article exploits a new approach for synthesis of carboxymethyl cellulose/poly 2-acrylamidoglycolic acid by graft and crosslinked copolymerization in aqueous solution by a simple one-step using c-radiation. The reaction parameters affecting the equilibrium swelling, i.e., mass ratio of AG to CMC and irradiation dose were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The structure, crystallinity, thermal stability, and surface morphology were characterized by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), respectively. FTIR proved that the grafting reaction occurred between the hydroxyl group of CMC and PAG chain. The thermal analysis data show that the prepared hydrogel is more thermally stable than pure CMC. The swelling behaviors in distilled water in various pH solutions, temperature and various ionic salt solutions (NaCl as monovalent, CaCl 2 as divalent and FeCl 3 as trivalent) were investigated in detail. The effect of cationic salt solutions on the swelling had the following order: Na 1 > Ca 21 > Fe 31 . In addition, the pH-reversibility was preliminarily investigated with alternating pH between 12 and 2. The equilibrium swelling of CMC/PAG was achieved in 70 min. The hydrogel was responsive to the pH and salts; it also has reversible swelling and deswelling character. POLYM. ENG. SCI., 54:2753-2761, 2014

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Section: Introductionmentioning

confidence: 99%

Radiation initiated synthesis of 2‐acrylamidoglycolic acid grafted carboxymethyl cellulose as pH‐sensitive hydrogel

El‐Mohdy

2013

Polymer Engineering & Sci

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Interphase-assisted suppression of electrode polarization in nanoparticulate-elastomeric composites

Meddeb

Ounaies

2023

Journal of Applied Physics

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The electrical properties of polymer nanocomposites are governed by the behavior of the internal charges. In particular, the interphase around the nanoparticles strongly influences the distribution and mobility of charge carriers within the nanocomposites, which, in turn, impacts the performance of these materials. In this work, we probe the internal charge behavior in the presence of nanoparticles with a focus on the low-frequency regime using a suite of techniques. By investigating the depolarizing currents and the dependence of the dielectric properties on the frequency and temperature, we demonstrate that the interphases redistribute the space charges, increase their trap depth, and suppress the electrode polarization in an elastomeric nanocomposite. Additionally, we study the effect of the nanoparticle content on the dielectric behavior by comparing the internal charge behavior of 1, 2, and 4 vol. % nanocomposites. At only 4 vol. % loading, the mobility of charge carriers is effectively limited, leading to lower dc conductivity compared to the unfilled elastomer, and 1 and 2 vol. % nanocomposites. These findings are based on the model materials used in this study, TiO2 nanoparticles and polydimethylsiloxane, and can be extended to other nanoparticulate-filled elastomer composites to design lightweight dielectrics, actuators, and sensors with improved capabilities. Judicious manipulation of interfacial phenomena in polymer nanocomposites—especially those with a dilute content of nanoparticles—provides a promising path forward for the design of materials with exceptional electrical and other physical properties.

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Dielectric Relaxation and Electrical Conductivity Study in Thiourea- Doped Poly (Vinyl Alcohol)

Fahmy

2001

International Journal of Polymeric Materials

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FT-IR, UV-spectroscopy and X-ray diffraction of thiourea-Poly (vinyl alcohol) (PVA) complexes have been investigated. It was observed that thiourea affected the structure of PVA. X-ray study revealed that as the thiourea salt increases the crystallinity of PVA increases. The dielectric properties of thiourea-PVA complexes were investigated in the frequency range 0.2 to 100 kHz and the temperature range 293 to 433 K. All samples are characterized by high values of dielectric permittivity at low frequencies and high temperatures. The results are discussed in terms of interfacial Maxwell-Wagner-Wars (MWS) polarization and space-charge polarization. Different relaxation modes, i x . , and a-relaxations have been observed in pure PVA. AC conductivity measurements of samples showed that the hopping conduction mechanism dominates at low temperature region, from room temperature to the glass transition temperature.

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Thermally stimulated depolarization currents in poly(vinyl alcohol) films

Cited by 4 publications

References 10 publications

Radiation initiated synthesis of 2‐acrylamidoglycolic acid grafted carboxymethyl cellulose as pH‐sensitive hydrogel

Radiation initiated synthesis of 2‐acrylamidoglycolic acid grafted carboxymethyl cellulose as pH‐sensitive hydrogel

Interphase-assisted suppression of electrode polarization in nanoparticulate-elastomeric composites

Dielectric Relaxation and Electrical Conductivity Study in Thiourea- Doped Poly (Vinyl Alcohol)

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