Machalická, Klára V.

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  • Machalická, Klára V. (3)
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Author's Bibliography

Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles

Obradović, Vera; Radovanović, Željko; Sejkot, Petr; Machalická, Klára V.; Vokáč, Miroslav

(Springer Nature Switzerland, 2024)

TY  - CHAP
AU  - Obradović, Vera
AU  - Radovanović, Željko
AU  - Sejkot, Petr
AU  - Machalická, Klára V.
AU  - Vokáč, Miroslav
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7068
AB  - The Kevlar fabric composites have a wide range of applications in the
body armor and lightweight vehicle-armor structures. Nanoparticles are one of the
most common nanofillers for these structures. In this research, the testing specimens have been made from the Kevlar fabrics impregnated with the poly (vinyl
butyral)/ethanol solution which had been reinforced with the ZnO nanoparticles.
The two-layered composite samples have been fabricated by means of hot compression. The immersion of the square Kevlar/PVB specimens for the water uptake
measurements has been performed according to the ISO 62 standard. The specimens have been immersed in a water bath filled with the distilled water (40 °C) in
the period of 8 weeks. The Kevlar/PVB specimens have been tested in accordance
with the ASTM D 3039 standard for the tensile properties and the ASTM D 790–
03 standard for the flexural properties. The tensile and bending characteristics of
the dry specimens have been compared with the ones that had undergone the water
immersion.
PB  - Springer Nature Switzerland
T2  - Modern Building Materials, Structures and Techniques
T1  - Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles
EP  - 277
SP  - 268
VL  - 392
DO  - 10.1007/978-3-031-44603-0_27
ER  - 
@inbook{
author = "Obradović, Vera and Radovanović, Željko and Sejkot, Petr and Machalická, Klára V. and Vokáč, Miroslav",
year = "2024",
abstract = "The Kevlar fabric composites have a wide range of applications in the
body armor and lightweight vehicle-armor structures. Nanoparticles are one of the
most common nanofillers for these structures. In this research, the testing specimens have been made from the Kevlar fabrics impregnated with the poly (vinyl
butyral)/ethanol solution which had been reinforced with the ZnO nanoparticles.
The two-layered composite samples have been fabricated by means of hot compression. The immersion of the square Kevlar/PVB specimens for the water uptake
measurements has been performed according to the ISO 62 standard. The specimens have been immersed in a water bath filled with the distilled water (40 °C) in
the period of 8 weeks. The Kevlar/PVB specimens have been tested in accordance
with the ASTM D 3039 standard for the tensile properties and the ASTM D 790–
03 standard for the flexural properties. The tensile and bending characteristics of
the dry specimens have been compared with the ones that had undergone the water
immersion.",
publisher = "Springer Nature Switzerland",
journal = "Modern Building Materials, Structures and Techniques",
booktitle = "Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles",
pages = "277-268",
volume = "392",
doi = "10.1007/978-3-031-44603-0_27"
}
Obradović, V., Radovanović, Ž., Sejkot, P., Machalická, K. V.,& Vokáč, M.. (2024). Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles. in Modern Building Materials, Structures and Techniques
Springer Nature Switzerland., 392, 268-277.
https://doi.org/10.1007/978-3-031-44603-0_27
Obradović V, Radovanović Ž, Sejkot P, Machalická KV, Vokáč M. Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles. in Modern Building Materials, Structures and Techniques. 2024;392:268-277.
doi:10.1007/978-3-031-44603-0_27 .
Obradović, Vera, Radovanović, Željko, Sejkot, Petr, Machalická, Klára V., Vokáč, Miroslav, "Effects of Water Immersion on Mechanical Properties of Kevlar Composites Reinforced with ZnO Nanoparticles" in Modern Building Materials, Structures and Techniques, 392 (2024):268-277,
https://doi.org/10.1007/978-3-031-44603-0_27 . .

Environmental durability of Kevlar composites reinforced with TiO2 nanoparticles

Obradović, Vera; Sejkot, Petr; Machalická, Klára V.; Vokáč, Miroslav

(2023)

TY  - CONF
AU  - Obradović, Vera
AU  - Sejkot, Petr
AU  - Machalická, Klára V.
AU  - Vokáč, Miroslav
PY  - 2023
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7070
AB  - In this research, the testing specimens were made from the Kevlar fabrics impregnated with 10
wt.% poly (vinyl butyral)/ethanol solution but with the addition of the TiO2 nanoparticles. The
tensile and bending properties of the dry specimens were compared with the ones that had been
immersed in a water bath filled with distilled water (40°C) in the period of 8 weeks.
The PVB/fabric weight ratio for the impregnation of the woven Kevlar fabric was 20 wt.%. The
Kevlar/PVB fabric composites were reinforced with the TiO2 nanoparticles in different
concentrations (1 wt.% or 2 wt.% of reinforcement regarding poly (vinyl butyral), PVB). The
two layers of composite fabrics were hot-pressed by using the digital press at a temperature of
170 °C for 30 minutes.
The immersion of the square Kevlar/PVB composite specimens for the water weight gain
measurements was performed according to the ISO 62 standard. The Kevlar/PVB specimens
were tested in accordance with the ASTM D 3039 standard for the tensile properties and ASTM
D 790-03 standard for the flexural properties.
During the tensile and the flexural test, the complete fracture of the specimens did not occur.
The addition of 2 wt.% TiO2 nanoparticles produced 39.8% and 24.3% improvement in the
tensile strength and tensile modulus, respectively, compared to the dry Kevlar/PVB specimens
without reinforcement. The tensile properties of all the immersed Kevlar/PVB composite
specimens had decreased values compared to the ones of their dry specimens.
Unlike the tensile test results, the best flexural properties (strength and modulus) were achieved
with the dry specimens with no particles due to the better bonding between their two
impregnated fabric layers since the presence of TiO2 nanoparticles reduced the shear
connection between the layers. However, there was not such a decline in the properties of the
wet specimens with nanoparticles which even made some improvement in the bending strength
compared to the wet Kevlar/PVB specimens.
C3  - Scientific Program and Book of Abstracts / 9th International Conference on Fatigue of Composites (ICFC9), Vicenza, University of Padova, 21-23 June 2023
T1  - Environmental durability of Kevlar composites reinforced with TiO2 nanoparticles
SP  - 48
UR  - https://hdl.handle.net/21.15107/rcub_technorep_7070
ER  - 
@conference{
author = "Obradović, Vera and Sejkot, Petr and Machalická, Klára V. and Vokáč, Miroslav",
year = "2023",
abstract = "In this research, the testing specimens were made from the Kevlar fabrics impregnated with 10
wt.% poly (vinyl butyral)/ethanol solution but with the addition of the TiO2 nanoparticles. The
tensile and bending properties of the dry specimens were compared with the ones that had been
immersed in a water bath filled with distilled water (40°C) in the period of 8 weeks.
The PVB/fabric weight ratio for the impregnation of the woven Kevlar fabric was 20 wt.%. The
Kevlar/PVB fabric composites were reinforced with the TiO2 nanoparticles in different
concentrations (1 wt.% or 2 wt.% of reinforcement regarding poly (vinyl butyral), PVB). The
two layers of composite fabrics were hot-pressed by using the digital press at a temperature of
170 °C for 30 minutes.
The immersion of the square Kevlar/PVB composite specimens for the water weight gain
measurements was performed according to the ISO 62 standard. The Kevlar/PVB specimens
were tested in accordance with the ASTM D 3039 standard for the tensile properties and ASTM
D 790-03 standard for the flexural properties.
During the tensile and the flexural test, the complete fracture of the specimens did not occur.
The addition of 2 wt.% TiO2 nanoparticles produced 39.8% and 24.3% improvement in the
tensile strength and tensile modulus, respectively, compared to the dry Kevlar/PVB specimens
without reinforcement. The tensile properties of all the immersed Kevlar/PVB composite
specimens had decreased values compared to the ones of their dry specimens.
Unlike the tensile test results, the best flexural properties (strength and modulus) were achieved
with the dry specimens with no particles due to the better bonding between their two
impregnated fabric layers since the presence of TiO2 nanoparticles reduced the shear
connection between the layers. However, there was not such a decline in the properties of the
wet specimens with nanoparticles which even made some improvement in the bending strength
compared to the wet Kevlar/PVB specimens.",
journal = "Scientific Program and Book of Abstracts / 9th International Conference on Fatigue of Composites (ICFC9), Vicenza, University of Padova, 21-23 June 2023",
title = "Environmental durability of Kevlar composites reinforced with TiO2 nanoparticles",
pages = "48",
url = "https://hdl.handle.net/21.15107/rcub_technorep_7070"
}
Obradović, V., Sejkot, P., Machalická, K. V.,& Vokáč, M.. (2023). Environmental durability of Kevlar composites reinforced with TiO2 nanoparticles. in Scientific Program and Book of Abstracts / 9th International Conference on Fatigue of Composites (ICFC9), Vicenza, University of Padova, 21-23 June 2023, 48.
https://hdl.handle.net/21.15107/rcub_technorep_7070
Obradović V, Sejkot P, Machalická KV, Vokáč M. Environmental durability of Kevlar composites reinforced with TiO2 nanoparticles. in Scientific Program and Book of Abstracts / 9th International Conference on Fatigue of Composites (ICFC9), Vicenza, University of Padova, 21-23 June 2023. 2023;:48.
https://hdl.handle.net/21.15107/rcub_technorep_7070 .
Obradović, Vera, Sejkot, Petr, Machalická, Klára V., Vokáč, Miroslav, "Environmental durability of Kevlar composites reinforced with TiO2 nanoparticles" in Scientific Program and Book of Abstracts / 9th International Conference on Fatigue of Composites (ICFC9), Vicenza, University of Padova, 21-23 June 2023 (2023):48,
https://hdl.handle.net/21.15107/rcub_technorep_7070 .

Effect of moisture absorption on the mechanical properties of Kolon/ epoxy composites

Obradović, Vera; Bajić, Danica; Sejkot, Petr; Fidanovski, Bojana; Machalická, Klára V.; Vokáč, Miroslav

(Royal Society of Chemistry, 2021)

TY  - CONF
AU  - Obradović, Vera
AU  - Bajić, Danica
AU  - Sejkot, Petr
AU  - Fidanovski, Bojana
AU  - Machalická, Klára V.
AU  - Vokáč, Miroslav
PY  - 2021
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7076
AB  - The para-aramid fibres (Kevlar, Twaron, Kolon) are high performance polymeric fibres characterized by their high tenacity, strength to weight ratio and impact resistance. They are used for the soft body armour structures in ballistics and for the manufacture of parts in aerospace and automotive industry.
In this study, the specimens were made from the two-layered Kolon fabrics impregnated with epoxy resin where some silicon carbide (SiC) microparticles or SiC nanofibres were added as reinforcement. These composite specimens
were fabricated by hot compression and curing of epoxy resin.
Despite their good mechanical strength it is a well-known fact that the mechanical properties of epoxy resins are affected by moisture absorption. The tensile and impact properties of the untreated specimens were compared with the ones that underwent water absorption in the duration of 72h (immersion or humidity) followed by desorption. The immersion of the specimens in water and the exposure to high humidity (70%) were completed in accordance with the ISO 62 standard while the tensile test was performed according to the ASTM D 3039 standard. Furthermore, the tensile test simulation of the Kolon/epoxy composite by using software Abaqus® was accomplished.
For the determination of the absorbed impact energy and the impact toughness of the composite specimens, an impact test was performed by using the Charpy impact pendulum in accordance with the ASTM D5942 standard.
PB  - Royal Society of Chemistry
C3  - Book of poster Abstracts / 15th International conference on materials chemistry (MC15) - online, United Kingdom, July 12-15, 2021
T1  - Effect of moisture absorption on the mechanical properties of Kolon/ epoxy composites
SP  - P104
UR  - https://hdl.handle.net/21.15107/rcub_technorep_7076
ER  - 
@conference{
author = "Obradović, Vera and Bajić, Danica and Sejkot, Petr and Fidanovski, Bojana and Machalická, Klára V. and Vokáč, Miroslav",
year = "2021",
abstract = "The para-aramid fibres (Kevlar, Twaron, Kolon) are high performance polymeric fibres characterized by their high tenacity, strength to weight ratio and impact resistance. They are used for the soft body armour structures in ballistics and for the manufacture of parts in aerospace and automotive industry.
In this study, the specimens were made from the two-layered Kolon fabrics impregnated with epoxy resin where some silicon carbide (SiC) microparticles or SiC nanofibres were added as reinforcement. These composite specimens
were fabricated by hot compression and curing of epoxy resin.
Despite their good mechanical strength it is a well-known fact that the mechanical properties of epoxy resins are affected by moisture absorption. The tensile and impact properties of the untreated specimens were compared with the ones that underwent water absorption in the duration of 72h (immersion or humidity) followed by desorption. The immersion of the specimens in water and the exposure to high humidity (70%) were completed in accordance with the ISO 62 standard while the tensile test was performed according to the ASTM D 3039 standard. Furthermore, the tensile test simulation of the Kolon/epoxy composite by using software Abaqus® was accomplished.
For the determination of the absorbed impact energy and the impact toughness of the composite specimens, an impact test was performed by using the Charpy impact pendulum in accordance with the ASTM D5942 standard.",
publisher = "Royal Society of Chemistry",
journal = "Book of poster Abstracts / 15th International conference on materials chemistry (MC15) - online, United Kingdom, July 12-15, 2021",
title = "Effect of moisture absorption on the mechanical properties of Kolon/ epoxy composites",
pages = "P104",
url = "https://hdl.handle.net/21.15107/rcub_technorep_7076"
}
Obradović, V., Bajić, D., Sejkot, P., Fidanovski, B., Machalická, K. V.,& Vokáč, M.. (2021). Effect of moisture absorption on the mechanical properties of Kolon/ epoxy composites. in Book of poster Abstracts / 15th International conference on materials chemistry (MC15) - online, United Kingdom, July 12-15, 2021
Royal Society of Chemistry., P104.
https://hdl.handle.net/21.15107/rcub_technorep_7076
Obradović V, Bajić D, Sejkot P, Fidanovski B, Machalická KV, Vokáč M. Effect of moisture absorption on the mechanical properties of Kolon/ epoxy composites. in Book of poster Abstracts / 15th International conference on materials chemistry (MC15) - online, United Kingdom, July 12-15, 2021. 2021;:P104.
https://hdl.handle.net/21.15107/rcub_technorep_7076 .
Obradović, Vera, Bajić, Danica, Sejkot, Petr, Fidanovski, Bojana, Machalická, Klára V., Vokáč, Miroslav, "Effect of moisture absorption on the mechanical properties of Kolon/ epoxy composites" in Book of poster Abstracts / 15th International conference on materials chemistry (MC15) - online, United Kingdom, July 12-15, 2021 (2021):P104,
https://hdl.handle.net/21.15107/rcub_technorep_7076 .