TY  - JOUR
AU  - Suljovrujić, Edin H.
PY  - 2010
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3985
AB  - The post-irradiation dielectric behaviour of different polyethylenes (PEs) has been studied by means of dielectric loss (tan 5) analysis over the wide temperature (25-325 K) and frequency (1 kHz-1 MHz) ranges. For this reason, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) samples were previously gamma irradiated in air to absorbed dose of 300 kGy. The irradiated samples were divided into two groups, and for the first one annealing treatment which can substantially reduce the concentration of free radicals were employed. For the second group, e.g. samples stored in air at room temperature after irradiation, post-irradiation evolution in free radical concentration, dielectric relaxation spectra and carbonyl content was investigated as a function of storage time, up to 90 days. Dielectric relaxation behaviour is related to differences in the initial structures of PEs (such as branching, crystallinity, etc.) and to the radiation-induced effects: carbonyl groups that were introduced by irradiation and/or delayed (post-irradiation) oxidation were regarded as tracer groups. Electron spin resonance (ESR), differential scanning calorimetry (DSC), infrared (IR) spectroscopy and gel measurements were used to determine the changes in free radical concentration, crystal fraction, oxidation and degree of network formation, respectively. (C) 2010 Elsevier Ltd. All rights reserved.
T2  - Radiation Physics and Chemistry
T1  - Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes
VL  - 79
IS  - 7
SP  - 751
EP  - 757
DO  - 10.1016/j.radphyschem.2010.02.008
ER  - 

@article{
author = "Suljovrujić, Edin H.",
year = "2010",
abstract = "The post-irradiation dielectric behaviour of different polyethylenes (PEs) has been studied by means of dielectric loss (tan 5) analysis over the wide temperature (25-325 K) and frequency (1 kHz-1 MHz) ranges. For this reason, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) samples were previously gamma irradiated in air to absorbed dose of 300 kGy. The irradiated samples were divided into two groups, and for the first one annealing treatment which can substantially reduce the concentration of free radicals were employed. For the second group, e.g. samples stored in air at room temperature after irradiation, post-irradiation evolution in free radical concentration, dielectric relaxation spectra and carbonyl content was investigated as a function of storage time, up to 90 days. Dielectric relaxation behaviour is related to differences in the initial structures of PEs (such as branching, crystallinity, etc.) and to the radiation-induced effects: carbonyl groups that were introduced by irradiation and/or delayed (post-irradiation) oxidation were regarded as tracer groups. Electron spin resonance (ESR), differential scanning calorimetry (DSC), infrared (IR) spectroscopy and gel measurements were used to determine the changes in free radical concentration, crystal fraction, oxidation and degree of network formation, respectively. (C) 2010 Elsevier Ltd. All rights reserved.",
journal = "Radiation Physics and Chemistry",
title = "Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes",
volume = "79",
number = "7",
pages = "751-757",
doi = "10.1016/j.radphyschem.2010.02.008"
}

Suljovrujić, E. H.. (2010). Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes. in Radiation Physics and Chemistry, 79(7), 751-757.
https://doi.org/10.1016/j.radphyschem.2010.02.008

Suljovrujić EH. Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes. in Radiation Physics and Chemistry. 2010;79(7):751-757.
doi:10.1016/j.radphyschem.2010.02.008 .

Suljovrujić, Edin H., "Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes" in Radiation Physics and Chemistry, 79, no. 7 (2010):751-757,
https://doi.org/10.1016/j.radphyschem.2010.02.008 . .

TY  - JOUR
AU  - Stamboliev, G.
AU  - Suljovrujić, Edin H.
PY  - 2010
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3968
AB  - The molecular relaxation behaviour of high density polyethylene (HDPE), exposed to gamma radiation in air to various absorbed doses (up to 700 kGy), has been investigated by dielectric loss (tan delta) analysis. All relaxation zones (gamma, beta and alpha, in order of increasing temperature), between 25 K and the melt 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 samples to radiation. Radiation-induced changes in the crystal fraction, oxidative degradation and degree of network formation, observed by wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and gel measurements, were well connected with the changes in intensity, position and activation energy of alpha and gamma relaxations. Complete disappearance of the already weak beta relaxation with irradiation is attributed to the more restricted chain segment mobility in the net Structure, but the contribution due to radiation-induced increase in crystallinity should also be taken into account. (C) 2009 Elsevier Ltd. All rights reserved.
T2  - Polymer Degradation and Stability
T1  - A dielectric study of molecular relaxations in irradiated high density polyethylene
VL  - 95
IS  - 4
SP  - 593
EP  - 599
DO  - 10.1016/j.polymdegradstab.2009.12.010
ER  - 

@article{
author = "Stamboliev, G. and Suljovrujić, Edin H.",
year = "2010",
abstract = "The molecular relaxation behaviour of high density polyethylene (HDPE), exposed to gamma radiation in air to various absorbed doses (up to 700 kGy), has been investigated by dielectric loss (tan delta) analysis. All relaxation zones (gamma, beta and alpha, in order of increasing temperature), between 25 K and the melt 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 samples to radiation. Radiation-induced changes in the crystal fraction, oxidative degradation and degree of network formation, observed by wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and gel measurements, were well connected with the changes in intensity, position and activation energy of alpha and gamma relaxations. Complete disappearance of the already weak beta relaxation with irradiation is attributed to the more restricted chain segment mobility in the net Structure, but the contribution due to radiation-induced increase in crystallinity should also be taken into account. (C) 2009 Elsevier Ltd. All rights reserved.",
journal = "Polymer Degradation and Stability",
title = "A dielectric study of molecular relaxations in irradiated high density polyethylene",
volume = "95",
number = "4",
pages = "593-599",
doi = "10.1016/j.polymdegradstab.2009.12.010"
}

Stamboliev, G.,& Suljovrujić, E. H.. (2010). A dielectric study of molecular relaxations in irradiated high density polyethylene. in Polymer Degradation and Stability, 95(4), 593-599.
https://doi.org/10.1016/j.polymdegradstab.2009.12.010

Stamboliev G, Suljovrujić EH. A dielectric study of molecular relaxations in irradiated high density polyethylene. in Polymer Degradation and Stability. 2010;95(4):593-599.
doi:10.1016/j.polymdegradstab.2009.12.010 .

Stamboliev, G., Suljovrujić, Edin H., "A dielectric study of molecular relaxations in irradiated high density polyethylene" in Polymer Degradation and Stability, 95, no. 4 (2010):593-599,
https://doi.org/10.1016/j.polymdegradstab.2009.12.010 . .