The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The α relaxation

Suljovrujić, E.; Trifunović, S.; Miličević, Dejan

doi:10.1016/j.polymdegradstab.2009.11.034

Cited by 19 publications

(22 citation statements)

References 57 publications

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“…Furthermore, an impressive study of the mechanical a relaxation as a two-component process was made by Tiemblo and collaborators for the case of iPP exposed to thermo-oxidation [16,17]; they proposed that the a relaxation makes it possible for crystals to act as radical scavengers and thus stabilize iPP exposed to thermo-oxidation at temperatures under 115°C. On the other hand, the dielectric a relaxation is almost unexplored [6]. Actually, very few experimental results are available, and most of them are made by TSDC measurements applied to investigate charge traps in crystalline parts [37,38].…”

Section: Resultsmentioning

confidence: 99%

“…The quantification of the various oxidation products of PP (as a result of gamma, photo, and thermal oxidation) was done by Lacoste et al [57,58]. The radiation-induced modifications that occur in the hydroxyl and carbonyl region were investigated in our previous papers [6,21,32], too. The major oxidation products in irradiated iPP are the tertiary hydroperoxides, which are unstable and undergo radical decomposition to other more stable oxidative products with an increase in radiation dose and their concentration.…”

Section: Resultsmentioning

confidence: 99%

“…According to Jourdan et al [7], the a relaxation is due to a relaxation of defects in the crystalline phase, but the amorphous phase in the neighbourhood of the crystallites also contributes to this process. This relaxation has a multiple nature, consisting of two or even more processes in the a relaxation zone [6,17,18]. The b relaxation is attributed to the glass-rubber transition in the amorphous phase of isotactic PP (iPP) [7].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, exposition to radiation can be used to increase the dielectric activity and to investigate low-visible dielectric relaxations in apolar polyolefins [19,25]. Even though the overall radiation chemistry of PP was investigated in detail and several comprehensive reviews are available on this topic [26][27][28][29][30][31], the effects of radiation on dielectric relaxation behaviour have not been investigated to an appreciable extent [6,19,21,[32][33][34]. A major application of high-energy radiation is cross-linking of insulation; cross-linking to a gel content of 55% was shown to be beneficial for cable insulation [26].…”

Section: Introductionmentioning

confidence: 99%

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Complete relaxation map of polypropylene: radiation-induced modification as dielectric probe

Suljovrujić

2012

Polym. Bull.

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The molecular relaxation behaviour of isotactic polypropylene (iPP) exposed to gamma radiation in air to various absorbed doses (up to 700 kGy) has been investigated by dielectric loss (tan d) analysis; the polar (mainly carbonyl and hydroperoxide) groups that were introduced by radiation-induced oxidation were considered as tracer groups. All relaxation zones (a, b, c and d in the order of decreasing temperature), between 25 K and melting temperature, were studied in the frequency range from 1 kHz to 1 MHz. The changes observed in the dielectric relaxation spectra were related to the modifications in the structural and morphological parameters attributed to exposure of the iPP samples to radiation. Wide-angle X-ray diffraction was used to investigate radiation-induced changes in the crystalline structure and degree of crystallinity, since the a relaxation is connected with this phase. Infrared spectroscopy and gel measurements were used to determine the changes in the oxidative degradation and the degree of network formation, respectively. Conclusions derived using different methods were compared. This study reveals high dielectric and/or relaxation sensitivity of iPP to gamma radiation. Disappearance of the lowtemperature dielectric (c and d) relaxations together with large changes in intensity, position and activation energy of the dielectric a relaxation are observed with gamma irradiation and are mainly connected with oxidative degradation in iPP structure.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Complete relaxation map of polypropylene: radiation-induced modification as dielectric probe

Suljovrujić

2012

Polym. Bull.

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“…A transition which is associated with the +-relaxation appeared at about 173 K in both composites. It has been previously reported that the +-relaxation of iPP appears between 150 and 230 K, and this relaxation is usually associated with the local motions in the amorphous phase [24]. The difference in conductivity between iPP and iPP/Ag slightly increases with increasing temperature up to this temperature, followed by a decrease at higher temperatures.…”

Section: Dielectric Propertiesmentioning

confidence: 91%

Influence of the presence of medium-soft paraffin wax on the morphology and properties of iPP/silver nanocomposites

Molaba¹,

Dudić²,

Luyt³

2015

Express Polym. Lett.

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γ‐Ray Irradiation Significantly Enhances Capacitive Energy Storage Performance of Polymer Dielectric Films

Wang,

Bao,

Ding

et al. 2024

Advanced Materials

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Polymer dielectric capacitors are fundamental in advanced electronics and power grids but suffer from low energy density, hindering miniaturization of compact electrical systems. We show that high‐energy and strong penetrating γ‐irradiation significantly enhances capacitive energy storage performance of polymer dielectrics. γ‐irradiated biaxially oriented polypropylene (BOPP) films exhibit an extraordinarily high energy density of ∼10.4 J cm−3 at ∼968 MV m−1 with an efficiency of ∼97.3%. In particular, an energy density of ∼4.06 J cm−3 with an ultrahigh efficiency of ∼98% is reliably maintained through 20,000 charge‐discharge cycles under 600 MV m−1. At 125 °C, the γ‐irradiated BOPP film still delivers a high discharged energy density of ∼5.88 J cm−3 with an efficiency of ∼90% at ∼770 MV m−1. Substantial improvements are also achieved for γ‐irradiated cycloolefin copolymers at a high temperature of 150 °C, verifying the strategy generalizability. Experimental and theoretical analyses reveal that the excellent performance should be related to the γ‐irradiation induced polar functional groups with high electron affinity in the molecular chain, which offer deep energy traps to impede charge transport. This work provides a simple and generally applicable strategy for developing high‐performance polymer dielectrics.This article is protected by copyright. All rights reserved

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The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The α relaxation

Cited by 19 publications

References 57 publications

Complete relaxation map of polypropylene: radiation-induced modification as dielectric probe

Complete relaxation map of polypropylene: radiation-induced modification as dielectric probe

Influence of the presence of medium-soft paraffin wax on the morphology and properties of iPP/silver nanocomposites

γ‐Ray Irradiation Significantly Enhances Capacitive Energy Storage Performance of Polymer Dielectric Films

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