TY  - JOUR
AU  - Kuska, Robert
AU  - Milovanović, Stoja
AU  - Frerich, Sulamith
AU  - Ivanović, Jasna
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5041
AB  - Thermal properties of extrusion and injection grade polylactic acid (PLA) were analysed using high pressure differential scanning calorimetry (HP-DSC) under CO2 pressures of up to 50 MPa. The greatest depression of melting point and degree of crystallinity of the samples occurred at 20–30 MPa (∼97–115 °C). Batch and semi-continuous processes for supercritical foaming and impregnation of PLA with thymol or thyme extract were performed at 30 MPa and 100–110 °C to prevent thymol degradation, decrease heating requirements and ease polymer processing. At these conditions, PLA foams containing 5.6% or 1.1% of thymol and 0.7% of thyme extract were obtained using static or dynamic batch impregnation and semi-continuous extraction-impregnation process for 7 h, respectively. DSC and HP-DSC analyses revealed more pronounced effect of scCO2 plasticizing than foaming on PLA crystallinity. Neat and impregnated PLA foams with pores size of 15-200 μm have potential for food packaging, biomedical and insulation applications.
PB  - Elsevier B.V.
T2  - Journal of Supercritical Fluids
T1  - Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design
EP  - 80
SP  - 71
VL  - 144
DO  - 10.1016/j.supflu.2018.10.008
ER  - 

@article{
author = "Kuska, Robert and Milovanović, Stoja and Frerich, Sulamith and Ivanović, Jasna",
year = "2019",
abstract = "Thermal properties of extrusion and injection grade polylactic acid (PLA) were analysed using high pressure differential scanning calorimetry (HP-DSC) under CO2 pressures of up to 50 MPa. The greatest depression of melting point and degree of crystallinity of the samples occurred at 20–30 MPa (∼97–115 °C). Batch and semi-continuous processes for supercritical foaming and impregnation of PLA with thymol or thyme extract were performed at 30 MPa and 100–110 °C to prevent thymol degradation, decrease heating requirements and ease polymer processing. At these conditions, PLA foams containing 5.6% or 1.1% of thymol and 0.7% of thyme extract were obtained using static or dynamic batch impregnation and semi-continuous extraction-impregnation process for 7 h, respectively. DSC and HP-DSC analyses revealed more pronounced effect of scCO2 plasticizing than foaming on PLA crystallinity. Neat and impregnated PLA foams with pores size of 15-200 μm have potential for food packaging, biomedical and insulation applications.",
publisher = "Elsevier B.V.",
journal = "Journal of Supercritical Fluids",
title = "Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design",
pages = "80-71",
volume = "144",
doi = "10.1016/j.supflu.2018.10.008"
}

Kuska, R., Milovanović, S., Frerich, S.,& Ivanović, J.. (2019). Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design. in Journal of Supercritical Fluids
Elsevier B.V.., 144, 71-80.
https://doi.org/10.1016/j.supflu.2018.10.008

Kuska R, Milovanović S, Frerich S, Ivanović J. Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design. in Journal of Supercritical Fluids. 2019;144:71-80.
doi:10.1016/j.supflu.2018.10.008 .

Kuska, Robert, Milovanović, Stoja, Frerich, Sulamith, Ivanović, Jasna, "Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design" in Journal of Supercritical Fluids, 144 (2019):71-80,
https://doi.org/10.1016/j.supflu.2018.10.008 . .

TY  - JOUR
AU  - Kuska, Robert
AU  - Milovanović, Stoja
AU  - Frerich, Sulamith
AU  - Ivanović, Jasna
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4328
AB  - Thermal properties of extrusion and injection grade polylactic acid (PLA) were analysed using high pressure differential scanning calorimetry (HP-DSC) under CO2 pressures of up to 50 MPa. The greatest depression of melting point and degree of crystallinity of the samples occurred at 20-30 MPa (similar to 97-115 degrees C). Batch and semi continuous processes for supercritical foaming and impregnation of PLA with thymol or thyme extract were performed at 30 MPa and 100-110 degrees C to prevent thymol degradation, decrease heating requirements and ease polymer processing. At these conditions, PLA foams containing 5.6% or 1.1% of thymol and 0.7% of thyme extract were obtained using static or dynamic batch impregnation and semi-continuous extraction-impregnation process for 7 h, respectively. DSC and HP-DSC analyses revealed more pronounced effect of scCO(2) plasticizing than foaming on PLA crystallinity. Neat and impregnated PLA foams with pores size of 15-200 pm have potential for food packaging, biomedical and insulation applications.
PB  - Elsevier Science Bv, Amsterdam
T2  - Journal of Supercritical Fluids
T1  - Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design
EP  - 80
SP  - 71
VL  - 144
DO  - 10.1016/j.supflu.2018.10.008
ER  - 

@article{
author = "Kuska, Robert and Milovanović, Stoja and Frerich, Sulamith and Ivanović, Jasna",
year = "2019",
abstract = "Thermal properties of extrusion and injection grade polylactic acid (PLA) were analysed using high pressure differential scanning calorimetry (HP-DSC) under CO2 pressures of up to 50 MPa. The greatest depression of melting point and degree of crystallinity of the samples occurred at 20-30 MPa (similar to 97-115 degrees C). Batch and semi continuous processes for supercritical foaming and impregnation of PLA with thymol or thyme extract were performed at 30 MPa and 100-110 degrees C to prevent thymol degradation, decrease heating requirements and ease polymer processing. At these conditions, PLA foams containing 5.6% or 1.1% of thymol and 0.7% of thyme extract were obtained using static or dynamic batch impregnation and semi-continuous extraction-impregnation process for 7 h, respectively. DSC and HP-DSC analyses revealed more pronounced effect of scCO(2) plasticizing than foaming on PLA crystallinity. Neat and impregnated PLA foams with pores size of 15-200 pm have potential for food packaging, biomedical and insulation applications.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Journal of Supercritical Fluids",
title = "Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design",
pages = "80-71",
volume = "144",
doi = "10.1016/j.supflu.2018.10.008"
}

Kuska, R., Milovanović, S., Frerich, S.,& Ivanović, J.. (2019). Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design. in Journal of Supercritical Fluids
Elsevier Science Bv, Amsterdam., 144, 71-80.
https://doi.org/10.1016/j.supflu.2018.10.008

Kuska R, Milovanović S, Frerich S, Ivanović J. Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design. in Journal of Supercritical Fluids. 2019;144:71-80.
doi:10.1016/j.supflu.2018.10.008 .

Kuska, Robert, Milovanović, Stoja, Frerich, Sulamith, Ivanović, Jasna, "Thermal analysis of polylactic acid under high CO2 pressure applied in supercritical impregnation and foaming process design" in Journal of Supercritical Fluids, 144 (2019):71-80,
https://doi.org/10.1016/j.supflu.2018.10.008 . .

TY  - JOUR
AU  - Milovanović, Stoja
AU  - Marković, Darka
AU  - Mraković, Ana
AU  - Kuska, Robert
AU  - Žižović, Irena
AU  - Frerich, Sulamith
AU  - Ivanović, Jasna
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4173
AB  - Amorphous, medical grade poly(D,L-lactic acid) (PLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) were used to develop systems for controlled release of a natural bioactive substance - thymol. Supercritical carbon dioxide (scCO(2)) was successfully used both as an impregnation medium for thymol incorporation into the polymer matrix and a foaming agent in a single-step batch process. Impregnation of samples using low to moderate scCO(2) densities (273 kg/m(3) and 630 kg/m(3)) and short processing times (2 h and 4 h) enabled thymol loading of 0.920/0-6.62% and formation of microcellular foams upon system depressurization. Thymol effect on structural and thermal properties on foamed samples was proven by FTIR and DSC. The effect of CO2 under elevated pressure on the neat polymers was analysed by high pressure DSC. Foaming of polymers with lower molecular weight by CO2 of higher density yielded foams with smaller pores. All tested foams released thymol in a controlled manner in phosphate buffered saline (PBS) at 37 degrees C within 3 to 6 weeks. Higher loading and lower cell density favoured thymol release rate, while its concentration in PBS for the tested period depended on foam interaction with the medium. Representative PLGA foam sample with the highest thymol loading (6.62%) showed controlled thymol release within 72 h in mediums having pH values from 1.1 to 7.4.
PB  - Elsevier Science Bv, Amsterdam
T2  - Materials Science & Engineering C-Materials for Biological Applications
T1  - Supercritical CO2 - assisted production of PLA and PLGA foams for controlled thymol release
EP  - 404
SP  - 394
VL  - 99
DO  - 10.1016/j.msec.2019.01.106
ER  - 

@article{
author = "Milovanović, Stoja and Marković, Darka and Mraković, Ana and Kuska, Robert and Žižović, Irena and Frerich, Sulamith and Ivanović, Jasna",
year = "2019",
abstract = "Amorphous, medical grade poly(D,L-lactic acid) (PLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) were used to develop systems for controlled release of a natural bioactive substance - thymol. Supercritical carbon dioxide (scCO(2)) was successfully used both as an impregnation medium for thymol incorporation into the polymer matrix and a foaming agent in a single-step batch process. Impregnation of samples using low to moderate scCO(2) densities (273 kg/m(3) and 630 kg/m(3)) and short processing times (2 h and 4 h) enabled thymol loading of 0.920/0-6.62% and formation of microcellular foams upon system depressurization. Thymol effect on structural and thermal properties on foamed samples was proven by FTIR and DSC. The effect of CO2 under elevated pressure on the neat polymers was analysed by high pressure DSC. Foaming of polymers with lower molecular weight by CO2 of higher density yielded foams with smaller pores. All tested foams released thymol in a controlled manner in phosphate buffered saline (PBS) at 37 degrees C within 3 to 6 weeks. Higher loading and lower cell density favoured thymol release rate, while its concentration in PBS for the tested period depended on foam interaction with the medium. Representative PLGA foam sample with the highest thymol loading (6.62%) showed controlled thymol release within 72 h in mediums having pH values from 1.1 to 7.4.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Materials Science & Engineering C-Materials for Biological Applications",
title = "Supercritical CO2 - assisted production of PLA and PLGA foams for controlled thymol release",
pages = "404-394",
volume = "99",
doi = "10.1016/j.msec.2019.01.106"
}

Milovanović, S., Marković, D., Mraković, A., Kuska, R., Žižović, I., Frerich, S.,& Ivanović, J.. (2019). Supercritical CO2 - assisted production of PLA and PLGA foams for controlled thymol release. in Materials Science & Engineering C-Materials for Biological Applications
Elsevier Science Bv, Amsterdam., 99, 394-404.
https://doi.org/10.1016/j.msec.2019.01.106

Milovanović S, Marković D, Mraković A, Kuska R, Žižović I, Frerich S, Ivanović J. Supercritical CO2 - assisted production of PLA and PLGA foams for controlled thymol release. in Materials Science & Engineering C-Materials for Biological Applications. 2019;99:394-404.
doi:10.1016/j.msec.2019.01.106 .

Milovanović, Stoja, Marković, Darka, Mraković, Ana, Kuska, Robert, Žižović, Irena, Frerich, Sulamith, Ivanović, Jasna, "Supercritical CO2 - assisted production of PLA and PLGA foams for controlled thymol release" in Materials Science & Engineering C-Materials for Biological Applications, 99 (2019):394-404,
https://doi.org/10.1016/j.msec.2019.01.106 . .

TY  - JOUR
AU  - Milovanović, Stoja
AU  - Hollermann, Gesa
AU  - Errenst, Cornelia
AU  - Pajnik, Jelena
AU  - Frerich, Sulamith
AU  - Kroll, Stephen
AU  - Rezwan, Kurosch
AU  - Ivanović, Jasna
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4037
AB  - Biodegradable polymers with antibacterial properties are highly desirable materials for active food packaging applications. Thymol, a dietary monoterpene phenol with a strong antibacterial activity is abundant in plants belonging to the genus Thymus. This study presents two approaches for supercritical CO2 impregnation of poly (lactic acid)(PLA)/poly(epsilon-caprolactone)(PCL) blended films to induce antibacterial properties of the material: (i) a batch impregnation process for loading pure thymol, and (ii) an integrated supercritical extraction-impregnation process for isolation of thyme extract and its incorporation into the films, operated in both batch or semi-continuous modes with supercritical solution circulation. The PCL content in films, impregnation time and CO2 flow regime were varied to maximize loading of the films with thymol or thyme extract with preserving films' structure and thermal stability. Representative film samples impregnated with thymol and thyme extract were tested against Gram ( - ) (Escherichia col) and Gram( + ) (Bacillus subtilis) model strains, by measuring their metabolic activity and re-cultivation after exposure to the films. The film containing thymol (35.8 wt%) showed a strong antibacterial activity leading to a total reduction of bacterial cell viability. Proposed processes enable fast, controlled and organic solvent-free fabrication of the PLA/PCL films containing natural antibacterial substances at moderately low temperature, with a compact structure and a good thermal stability, for potential use as active food packaging materials.
PB  - Elsevier Science Bv, Amsterdam
T2  - Food Research International
T1  - Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging
EP  - 495
SP  - 486
VL  - 107
DO  - 10.1016/j.foodres.2018.02.065
ER  - 

@article{
author = "Milovanović, Stoja and Hollermann, Gesa and Errenst, Cornelia and Pajnik, Jelena and Frerich, Sulamith and Kroll, Stephen and Rezwan, Kurosch and Ivanović, Jasna",
year = "2018",
abstract = "Biodegradable polymers with antibacterial properties are highly desirable materials for active food packaging applications. Thymol, a dietary monoterpene phenol with a strong antibacterial activity is abundant in plants belonging to the genus Thymus. This study presents two approaches for supercritical CO2 impregnation of poly (lactic acid)(PLA)/poly(epsilon-caprolactone)(PCL) blended films to induce antibacterial properties of the material: (i) a batch impregnation process for loading pure thymol, and (ii) an integrated supercritical extraction-impregnation process for isolation of thyme extract and its incorporation into the films, operated in both batch or semi-continuous modes with supercritical solution circulation. The PCL content in films, impregnation time and CO2 flow regime were varied to maximize loading of the films with thymol or thyme extract with preserving films' structure and thermal stability. Representative film samples impregnated with thymol and thyme extract were tested against Gram ( - ) (Escherichia col) and Gram( + ) (Bacillus subtilis) model strains, by measuring their metabolic activity and re-cultivation after exposure to the films. The film containing thymol (35.8 wt%) showed a strong antibacterial activity leading to a total reduction of bacterial cell viability. Proposed processes enable fast, controlled and organic solvent-free fabrication of the PLA/PCL films containing natural antibacterial substances at moderately low temperature, with a compact structure and a good thermal stability, for potential use as active food packaging materials.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Food Research International",
title = "Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging",
pages = "495-486",
volume = "107",
doi = "10.1016/j.foodres.2018.02.065"
}

Milovanović, S., Hollermann, G., Errenst, C., Pajnik, J., Frerich, S., Kroll, S., Rezwan, K.,& Ivanović, J.. (2018). Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging. in Food Research International
Elsevier Science Bv, Amsterdam., 107, 486-495.
https://doi.org/10.1016/j.foodres.2018.02.065

Milovanović S, Hollermann G, Errenst C, Pajnik J, Frerich S, Kroll S, Rezwan K, Ivanović J. Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging. in Food Research International. 2018;107:486-495.
doi:10.1016/j.foodres.2018.02.065 .

Milovanović, Stoja, Hollermann, Gesa, Errenst, Cornelia, Pajnik, Jelena, Frerich, Sulamith, Kroll, Stephen, Rezwan, Kurosch, Ivanović, Jasna, "Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging" in Food Research International, 107 (2018):486-495,
https://doi.org/10.1016/j.foodres.2018.02.065 . .

TY  - JOUR
AU  - Milovanović, Stoja
AU  - Kuska, Robert
AU  - Lučić-Škorić, Marija
AU  - Kalagasidis Krušić, Melina
AU  - Frerich, Sulamith
AU  - Žižović, Irena
AU  - Ivanović, Jasna
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3219
AB  - The present work was aimed to study swelling kinetics of polylactic acid (PLA) and its impregnation with thymol in supercritical carbon dioxide (scCO2) medium. The influences of temperature and soaking time on the swelling kinetics and impregnation yield of PLA cylindrical disc and film were investigated. Swelling experiments were performed in a high pressure view cell at 10 MPa and temperatures of 40°C, 60°C and 75°C for 2 to 24 h. On the basis of swelling kinetics, pressure of 10 MPa and temperature of 40°C were chosen for supercritical solvent impregnation (SSI) of the PLA samples during 2 to24 h. The highest swelling extent was observed for the PLA monolith after 24 h treatment with pure scCO2 (7.5%) and scCO2 with thymol (118.3%). It was shown that sufficiently high amount of thymol can be loaded into both PLA monolith and film using SSI after only 2 h (10.0% and 6.6%, respectively). Monolith and film of PLA impregnated with thymol could be suitable for active food packaging and sterile medical disposables.
AB  - Prikazana studija je namenjena ispitivanju kinetike bubrenja polilaktida (PLA) i njegovoj impregnaciji timolom u natkritičnom ugljenik(IV)-oksidu (nkCO2). Praćen je uticaj temperature i operativnog vremena na kinetiku bubrenja i prinos impregnacije PLA cilindričnog diska i filma. Eksperimenti bubrenja su izvedeni u ćeliji za rad pod visokim pritiscima na 10 MPa and 40°C, 60°C i 75°C od 2 h do 24 h. Na osnovu kinetike bubrenja, natkritična impregnacija uzoraka PLA timolom je izvedena na pritisku od 10 MPa i temperaturi od 40°C tokom 2 do 24 h. Najveći stepen bubrenja je imao PLA disk na 10 MPa i 40°C nakon 24 h (7,5%) u sistemu sa čistim nkCO2 i u sistemu sa timolom (118,3%). Pokazano je da se dovoljno visok prinos impregnacije timola može postići nakon 2 h (10,0% za disk i 6,6% za film). PLA u formi diska i filma impregnirani timolom su pogodni materijali za aktivno pakovanje hrane i za sterilni medicinski pribor.
PB  - Savez inženjera i tehničara Srbije, Beograd
T2  - Tehnika
T1  - Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions
T1  - Kinetika bubrenja PLA i njegova impregnacija timolom upotrebom natkritičnog uglenik(IV)-oksida
EP  - 20
IS  - 1
SP  - 16
VL  - 71
DO  - 10.5937/tehnika1601016M
ER  - 

@article{
author = "Milovanović, Stoja and Kuska, Robert and Lučić-Škorić, Marija and Kalagasidis Krušić, Melina and Frerich, Sulamith and Žižović, Irena and Ivanović, Jasna",
year = "2016",
abstract = "The present work was aimed to study swelling kinetics of polylactic acid (PLA) and its impregnation with thymol in supercritical carbon dioxide (scCO2) medium. The influences of temperature and soaking time on the swelling kinetics and impregnation yield of PLA cylindrical disc and film were investigated. Swelling experiments were performed in a high pressure view cell at 10 MPa and temperatures of 40°C, 60°C and 75°C for 2 to 24 h. On the basis of swelling kinetics, pressure of 10 MPa and temperature of 40°C were chosen for supercritical solvent impregnation (SSI) of the PLA samples during 2 to24 h. The highest swelling extent was observed for the PLA monolith after 24 h treatment with pure scCO2 (7.5%) and scCO2 with thymol (118.3%). It was shown that sufficiently high amount of thymol can be loaded into both PLA monolith and film using SSI after only 2 h (10.0% and 6.6%, respectively). Monolith and film of PLA impregnated with thymol could be suitable for active food packaging and sterile medical disposables., Prikazana studija je namenjena ispitivanju kinetike bubrenja polilaktida (PLA) i njegovoj impregnaciji timolom u natkritičnom ugljenik(IV)-oksidu (nkCO2). Praćen je uticaj temperature i operativnog vremena na kinetiku bubrenja i prinos impregnacije PLA cilindričnog diska i filma. Eksperimenti bubrenja su izvedeni u ćeliji za rad pod visokim pritiscima na 10 MPa and 40°C, 60°C i 75°C od 2 h do 24 h. Na osnovu kinetike bubrenja, natkritična impregnacija uzoraka PLA timolom je izvedena na pritisku od 10 MPa i temperaturi od 40°C tokom 2 do 24 h. Najveći stepen bubrenja je imao PLA disk na 10 MPa i 40°C nakon 24 h (7,5%) u sistemu sa čistim nkCO2 i u sistemu sa timolom (118,3%). Pokazano je da se dovoljno visok prinos impregnacije timola može postići nakon 2 h (10,0% za disk i 6,6% za film). PLA u formi diska i filma impregnirani timolom su pogodni materijali za aktivno pakovanje hrane i za sterilni medicinski pribor.",
publisher = "Savez inženjera i tehničara Srbije, Beograd",
journal = "Tehnika",
title = "Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions, Kinetika bubrenja PLA i njegova impregnacija timolom upotrebom natkritičnog uglenik(IV)-oksida",
pages = "20-16",
number = "1",
volume = "71",
doi = "10.5937/tehnika1601016M"
}

Milovanović, S., Kuska, R., Lučić-Škorić, M., Kalagasidis Krušić, M., Frerich, S., Žižović, I.,& Ivanović, J.. (2016). Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions. in Tehnika
Savez inženjera i tehničara Srbije, Beograd., 71(1), 16-20.
https://doi.org/10.5937/tehnika1601016M

Milovanović S, Kuska R, Lučić-Škorić M, Kalagasidis Krušić M, Frerich S, Žižović I, Ivanović J. Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions. in Tehnika. 2016;71(1):16-20.
doi:10.5937/tehnika1601016M .

Milovanović, Stoja, Kuska, Robert, Lučić-Škorić, Marija, Kalagasidis Krušić, Melina, Frerich, Sulamith, Žižović, Irena, Ivanović, Jasna, "Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions" in Tehnika, 71, no. 1 (2016):16-20,
https://doi.org/10.5937/tehnika1601016M . .