TY  - JOUR
AU  - Miličević, Dejan S.
AU  - Trifunovic, S.
AU  - Dojčilović, Jablan R.
AU  - Ignjatović, Nenad L.
AU  - Suljovrujić, Edin H.
PY  - 2010
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4096
AB  - The influence of gamma radiation on the molecular weight and glass transition behaviour of poly-L-lactide (PLLA) and hydroxyapatite/poly-L-lactide (HAp/PLLA) nanocomposite has been studied Since PLLA exposed to high-energy radiation in the presence of air is prone to chain scission reactions and large degradation, changes in molecular weight were obtained by gel permeation chromatography (GPC). Alterations in the glass transition behaviour were investigated by differential scanning calorimetry (DSC) The apparent activation energy (Delta H*) for glass transition was determined on the basis of the heating rate dependence of the glass transition temperature (T-g). Our findings support the fact that chain scission is the main reason for the decrease of T-g and Delta H* with the absorbed dose Furthermore, more intensive chain scission degradation of PLLA was observed in HAp/PLLA and can only be ascribed to the presence of HAp nanoparticles. Consequently, initial differences in the glass transition temperature and/or apparent activation energy of PLLA and HAp/PLLA became more pronounced with absorbed dose. This study reveals that radiation-induced changes in molecular weight and glass transition temperature occur in a predictable and fairly accurate manner Therefore, gamma radiation can be used not only for sterilization but also for tailoring desirable end-use properties of these biomaterials (C) 2010 Elsevier B V. All rights reserved
T2  - Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms
T1  - The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite
VL  - 268
IS  - 17-18
SP  - 2744
EP  - 2749
DO  - 10.1016/j.nimb.2010.06.036
ER  - 

@article{
author = "Miličević, Dejan S. and Trifunovic, S. and Dojčilović, Jablan R. and Ignjatović, Nenad L. and Suljovrujić, Edin H.",
year = "2010",
abstract = "The influence of gamma radiation on the molecular weight and glass transition behaviour of poly-L-lactide (PLLA) and hydroxyapatite/poly-L-lactide (HAp/PLLA) nanocomposite has been studied Since PLLA exposed to high-energy radiation in the presence of air is prone to chain scission reactions and large degradation, changes in molecular weight were obtained by gel permeation chromatography (GPC). Alterations in the glass transition behaviour were investigated by differential scanning calorimetry (DSC) The apparent activation energy (Delta H*) for glass transition was determined on the basis of the heating rate dependence of the glass transition temperature (T-g). Our findings support the fact that chain scission is the main reason for the decrease of T-g and Delta H* with the absorbed dose Furthermore, more intensive chain scission degradation of PLLA was observed in HAp/PLLA and can only be ascribed to the presence of HAp nanoparticles. Consequently, initial differences in the glass transition temperature and/or apparent activation energy of PLLA and HAp/PLLA became more pronounced with absorbed dose. This study reveals that radiation-induced changes in molecular weight and glass transition temperature occur in a predictable and fairly accurate manner Therefore, gamma radiation can be used not only for sterilization but also for tailoring desirable end-use properties of these biomaterials (C) 2010 Elsevier B V. All rights reserved",
journal = "Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms",
title = "The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite",
volume = "268",
number = "17-18",
pages = "2744-2749",
doi = "10.1016/j.nimb.2010.06.036"
}

Miličević, D. S., Trifunovic, S., Dojčilović, J. R., Ignjatović, N. L.,& Suljovrujić, E. H.. (2010). The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite. in Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms, 268(17-18), 2744-2749.
https://doi.org/10.1016/j.nimb.2010.06.036

Miličević DS, Trifunovic S, Dojčilović JR, Ignjatović NL, Suljovrujić EH. The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite. in Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. 2010;268(17-18):2744-2749.
doi:10.1016/j.nimb.2010.06.036 .

Miličević, Dejan S., Trifunovic, S., Dojčilović, Jablan R., Ignjatović, Nenad L., Suljovrujić, Edin H., "The influence of gamma radiation on the molecular weight and glass transition of PLLA and HAp/PLLA nanocomposite" in Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms, 268, no. 17-18 (2010):2744-2749,
https://doi.org/10.1016/j.nimb.2010.06.036 . .

TY  - JOUR
AU  - Suljovrujić, Edin H.
AU  - Trifunovic, S.
AU  - Miličević, Dejan S.
PY  - 2010
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3910
AB  - The high-temperature a relaxation in gamma irradiated isotactic polypropylene (iPP) was studied over the temperature (298-406 K), frequency (10(3)-10(6) Hz) and absorbed dose (0-700 kGy) ranges by means of dielectric spectroscopy. The multiple a relaxation was resolved from the 0 relaxation by curve fitting and its parameters were determined. Its position, intensity and activation energy were found to be strongly dependent on the changes in the structural and morphological parameters attributed to the exposure of the samples to radiation. Wide angle X-ray diffraction (WAXD) was used to investigate radiation-induced changes in the crystalline structure and degree of crystallinity, since this relaxation is connected with the crystal phase. Infrared (IR) spectroscopy and gel measurements were used to determine the changes in the oxidative degradation and the degree of network formation, respectively; the polar (carbonyl and/or hydroperoxide) groups that were introduced by irradiation were considered as tracer groups. Conclusions derived according to different methods were compared. The results reveal uncommon a relaxation behaviour with gamma radiation and confirm the multiple nature of this process, together with high dielectric and/or relaxation sensitivity of iPP to the radiation-induced changes. (C) 2009 Elsevier Ltd. All rights reserved.
T2  - Polymer Degradation and Stability
T1  - The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The alpha relaxation
VL  - 95
IS  - 2
SP  - 164
EP  - 171
DO  - 10.1016/j.polymdegradstab.2009.11.034
ER  - 

@article{
author = "Suljovrujić, Edin H. and Trifunovic, S. and Miličević, Dejan S.",
year = "2010",
abstract = "The high-temperature a relaxation in gamma irradiated isotactic polypropylene (iPP) was studied over the temperature (298-406 K), frequency (10(3)-10(6) Hz) and absorbed dose (0-700 kGy) ranges by means of dielectric spectroscopy. The multiple a relaxation was resolved from the 0 relaxation by curve fitting and its parameters were determined. Its position, intensity and activation energy were found to be strongly dependent on the changes in the structural and morphological parameters attributed to the exposure of the samples to radiation. Wide angle X-ray diffraction (WAXD) was used to investigate radiation-induced changes in the crystalline structure and degree of crystallinity, since this relaxation is connected with the crystal phase. Infrared (IR) spectroscopy and gel measurements were used to determine the changes in the oxidative degradation and the degree of network formation, respectively; the polar (carbonyl and/or hydroperoxide) groups that were introduced by irradiation were considered as tracer groups. Conclusions derived according to different methods were compared. The results reveal uncommon a relaxation behaviour with gamma radiation and confirm the multiple nature of this process, together with high dielectric and/or relaxation sensitivity of iPP to the radiation-induced changes. (C) 2009 Elsevier Ltd. All rights reserved.",
journal = "Polymer Degradation and Stability",
title = "The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The alpha relaxation",
volume = "95",
number = "2",
pages = "164-171",
doi = "10.1016/j.polymdegradstab.2009.11.034"
}

Suljovrujić, E. H., Trifunovic, S.,& Miličević, D. S.. (2010). The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The alpha relaxation. in Polymer Degradation and Stability, 95(2), 164-171.
https://doi.org/10.1016/j.polymdegradstab.2009.11.034

Suljovrujić EH, Trifunovic S, Miličević DS. The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The alpha relaxation. in Polymer Degradation and Stability. 2010;95(2):164-171.
doi:10.1016/j.polymdegradstab.2009.11.034 .

Suljovrujić, Edin H., Trifunovic, S., Miličević, Dejan S., "The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The alpha relaxation" in Polymer Degradation and Stability, 95, no. 2 (2010):164-171,
https://doi.org/10.1016/j.polymdegradstab.2009.11.034 . .

TY  - JOUR
AU  - Suljovrujić, Edin H.
PY  - 2009
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3744
AB  - This paper presents a study of the influence of structural peculiarities, uniaxial orientation and fibrillar structure on the radiation-induced changes in iPP. For the purposes of this study, iPP was oriented via solid-state stretching at elevated temperature to various draw ratios and, later on, gamma irradiated in air. In order to investigate orientation- and/or radiation-induced structural changes, optical microscopy (OM), scanning electron microscopy (SEM), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and gel measurements were employed. To quantify the degree of molecular orientation, Hermans orientation function (f(c)), was used. IR spectroscopy and gel measurements were used to determine the changes in the oxidative degradation and degree of network formation, respectively. Sol-gel analysis was studied in detail using the Charlesby-Pinner (C-P) equation. The radiation-induced changes in the structure and evolution of oxygen-containing species were also studied through dielectric loss (tan delta) analysis in a wide frequency range; the polar groups that were introduced by irradiation in apolar iPP were considered as tracer groups. Conclusions derived according to different methods were compared. Presented results reveal two different radiation-induced dynamics; gamma irradiation of initial and fully developed fibrillar iPP structures leads to significantly different crosslinking and/or oxidation response. (C) 2009 Elsevier Ltd. All rights reserved.
T2  - European Polymer Journal
T1  - The influence of molecular orientation on the crosslinking/oxidative behaviour of iPP exposed to gamma radiation
VL  - 45
IS  - 7
SP  - 2068
EP  - 2078
DO  - 10.1016/j.eurpolymj.2009.03.017
ER  - 

@article{
author = "Suljovrujić, Edin H.",
year = "2009",
abstract = "This paper presents a study of the influence of structural peculiarities, uniaxial orientation and fibrillar structure on the radiation-induced changes in iPP. For the purposes of this study, iPP was oriented via solid-state stretching at elevated temperature to various draw ratios and, later on, gamma irradiated in air. In order to investigate orientation- and/or radiation-induced structural changes, optical microscopy (OM), scanning electron microscopy (SEM), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and gel measurements were employed. To quantify the degree of molecular orientation, Hermans orientation function (f(c)), was used. IR spectroscopy and gel measurements were used to determine the changes in the oxidative degradation and degree of network formation, respectively. Sol-gel analysis was studied in detail using the Charlesby-Pinner (C-P) equation. The radiation-induced changes in the structure and evolution of oxygen-containing species were also studied through dielectric loss (tan delta) analysis in a wide frequency range; the polar groups that were introduced by irradiation in apolar iPP were considered as tracer groups. Conclusions derived according to different methods were compared. Presented results reveal two different radiation-induced dynamics; gamma irradiation of initial and fully developed fibrillar iPP structures leads to significantly different crosslinking and/or oxidation response. (C) 2009 Elsevier Ltd. All rights reserved.",
journal = "European Polymer Journal",
title = "The influence of molecular orientation on the crosslinking/oxidative behaviour of iPP exposed to gamma radiation",
volume = "45",
number = "7",
pages = "2068-2078",
doi = "10.1016/j.eurpolymj.2009.03.017"
}

Suljovrujić, E. H.. (2009). The influence of molecular orientation on the crosslinking/oxidative behaviour of iPP exposed to gamma radiation. in European Polymer Journal, 45(7), 2068-2078.
https://doi.org/10.1016/j.eurpolymj.2009.03.017

Suljovrujić EH. The influence of molecular orientation on the crosslinking/oxidative behaviour of iPP exposed to gamma radiation. in European Polymer Journal. 2009;45(7):2068-2078.
doi:10.1016/j.eurpolymj.2009.03.017 .

Suljovrujić, Edin H., "The influence of molecular orientation on the crosslinking/oxidative behaviour of iPP exposed to gamma radiation" in European Polymer Journal, 45, no. 7 (2009):2068-2078,
https://doi.org/10.1016/j.eurpolymj.2009.03.017 . .

TY  - JOUR
AU  - Suljovrujić, Edin H.
PY  - 2009
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3676
AB  - In this work, changes in structure and physical properties of stabilized isotactic polypropylene (iPP) were created by gamma irradiation, up to a dose of 700 kGy, in different media: air, deionised distilled (DD) water and acetylene. Gel and infrared (IR) spectroscopy measurements were used to determine the changes in the degree of network formation and oxidative degradation, respectively. Sol-gel analysis was studied in detail using the Charlesby-Pinner (C-P) equation. The radiation-induced changes in the structure and evolution of oxygen-containing species were also studied through dielectric loss (tan delta) analysis in a wide temperature and/or frequency range. Evolution of low temperature dielectric relaxations with gamma irradiation was investigated. In the case of dielectric relaxation measurements, the polar groups that were introduced by irradiation in non-polar iPP were considered as tracer groups. Conclusions derived according to different methods were compared. (c) 2009 Elsevier Ltd. All rights reserved.
T2  - Polymer Degradation and Stability
T1  - Gel production, oxidative degradation and dielectric properties of isotactic polypropylene irradiated under various atmospheres
VL  - 94
IS  - 4
SP  - 521
EP  - 526
DO  - 10.1016/j.polymdegradstab.2009.01.029
ER  - 

@article{
author = "Suljovrujić, Edin H.",
year = "2009",
abstract = "In this work, changes in structure and physical properties of stabilized isotactic polypropylene (iPP) were created by gamma irradiation, up to a dose of 700 kGy, in different media: air, deionised distilled (DD) water and acetylene. Gel and infrared (IR) spectroscopy measurements were used to determine the changes in the degree of network formation and oxidative degradation, respectively. Sol-gel analysis was studied in detail using the Charlesby-Pinner (C-P) equation. The radiation-induced changes in the structure and evolution of oxygen-containing species were also studied through dielectric loss (tan delta) analysis in a wide temperature and/or frequency range. Evolution of low temperature dielectric relaxations with gamma irradiation was investigated. In the case of dielectric relaxation measurements, the polar groups that were introduced by irradiation in non-polar iPP were considered as tracer groups. Conclusions derived according to different methods were compared. (c) 2009 Elsevier Ltd. All rights reserved.",
journal = "Polymer Degradation and Stability",
title = "Gel production, oxidative degradation and dielectric properties of isotactic polypropylene irradiated under various atmospheres",
volume = "94",
number = "4",
pages = "521-526",
doi = "10.1016/j.polymdegradstab.2009.01.029"
}

Suljovrujić, E. H.. (2009). Gel production, oxidative degradation and dielectric properties of isotactic polypropylene irradiated under various atmospheres. in Polymer Degradation and Stability, 94(4), 521-526.
https://doi.org/10.1016/j.polymdegradstab.2009.01.029

Suljovrujić EH. Gel production, oxidative degradation and dielectric properties of isotactic polypropylene irradiated under various atmospheres. in Polymer Degradation and Stability. 2009;94(4):521-526.
doi:10.1016/j.polymdegradstab.2009.01.029 .

Suljovrujić, Edin H., "Gel production, oxidative degradation and dielectric properties of isotactic polypropylene irradiated under various atmospheres" in Polymer Degradation and Stability, 94, no. 4 (2009):521-526,
https://doi.org/10.1016/j.polymdegradstab.2009.01.029 . .