The influence of chemical structure on the dielectric behavior of polypropylene

Banford, H.M.; Fouracre, R.A.; Faucitano, A.; Buttafava, A.; Martinotti, F.

doi:10.1109/94.536740

Cited by 32 publications

(12 citation statements)

References 4 publications

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“…Changes in the intensity of dielectric b and a relaxations with gamma irradiation are related to radiation-induced oxidation. The radiation-induced increase in the amount of carbonyl, hydroperoxide and other polar groups in apolar iPP causes modification of the dielectric properties due to the increase in polymer polarity [19,33,34,[48][49][50]. Moreover, it is known that polar groups generate shallow traps and enhance charge injection [5,51,52].…”

Section: Resultsmentioning

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%

“…In general, radiation-induced structure modifications can be exploited not only from the standpoint of commercial applications but also as a useful tool for highlighting some of the fundamental processes and properties of polymers. 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].…”

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: Introductionmentioning

confidence: 99%

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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“…When the carbonized deposits bridged the interval between electrodes, a sudden decrease in the insulating resistance occurred. The importance of this information has been revealed for preventing fires, shortcircuit and insulation failure in electrical appliances and devices, and especially the tracking and ignition of polymers have been examined [4][5].…”

Section: Introductionmentioning

confidence: 99%

Effects of atmospheric pressure on tracking failure of gamma-ray irradiated polymer insulating materials

Liu

2010

IEEE Trans. Dielect. Electr. Insul.

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With the increasing application of electric and electronic devices in space and nuclear power stations, the polymer insulation materials are inevitably exposed to various kinds of environments. As technology advances, increasing demands on the reliable operation under various operating and environmental conditions are made on materials and components. Therefore, it is important to investigate the influence of radiation on polymeric insulating materials used under the combined environments. This paper describes the effects of atmospheric pressure and gammaray irradiation on tracking failure of polybutylene naphthalate (PBN), polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. PBN, PET and PBT were irradiated in air up to 100 kGy and then up to 1000 kGy with a dose rate of 10 kGy/h by using a 60 Co gamma-source. The effects of total dose of irradiation and atmospheric pressure on the time to tracking failure and discharge quantity were discussed. Obtained results show that, with increasing the total dose, the time to tracking failure increased with PBN and PET, but decreased with PBT. With decreasing the atmospheric pressure, the time to tracking failure increased with PBN, PET and PBT. While increasing the total dose, the discharge quantity decreased with PBN and PET, but increased with PBT. With decreasing the atmospheric pressure, the discharge quantity increased with PBN and PET, but decreased with PBT. The experimental results suggest that the chemical structure of the polymeric insulating materials plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

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“…When sufficiently intensive discharge lasted for a considerable time, the decomposed carbon products, with some parts of the channel carbonized, were progressive and rapidly formed on the sample surface [4]. When the carbonized deposits bridged the interval between the electrodes, a sudden decrease in the insulating resistance occurred [5][6]. The importance of this information for preventing fires, short-circuit, insulation failure in electrical appliances and devices has been established, and especially the tracking and ignition of polymers have been examined.…”

Section: Introductionmentioning

confidence: 99%

Effects of gamma-ray irradiation on dielectric surface breakdown of polybutylene polymers

Liu

2007

IEEE Trans. Dielect. Electr. Insul.

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Polymer materials are required to be used in radiation environments of space and nuclear power stations as insulation materials. For the use of polymer materials in such regions, it must be confirmed whether the electrical performance under radiation environments is different from that without radiation. This paper describes the effects of gamma-ray irradiation on dielectric breakdown of polybutylene naphthalate and terephthalate by applying a dc pulse voltage. Both the polybutylene naphthalate and polybutylene terephthalate were irradiated in air up to 100 kGy and then up to 1000 kGy with dose rate of 10 kGy/h by using a 60 Co gamma-source. The total dose of gamma-ray irradiation effects on the time to dielectric breakdown and the discharge quantity of discharge current were discussed. Obtained results show that with increasing the total dose of gamma-ray irradiation, the time to dielectric breakdown increased with polybutylene naphthalate, but decreased with polybutylene terephalate. With increasing the total dose of gamma-ray irradiation, the discharge quantity decreased with polybutylene naphthalate, but increased with polybutylene terephalate. The experimental results suggest that the chemical structure plays a main role in the result of the radiation reaction, which is related to cross-linking and degradation reactions. Dielectric properties are improved by the irradiation for polybutylene polymers which contain more combined phenyls in the main chain.

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The influence of chemical structure on the dielectric behavior of polypropylene

Cited by 32 publications

References 4 publications

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

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

Effects of atmospheric pressure on tracking failure of gamma-ray irradiated polymer insulating materials

Effects of gamma-ray irradiation on dielectric surface breakdown of polybutylene polymers

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