TY  - JOUR
AU  - Machalická, Klára V.
AU  - Sejkot, Petr
AU  - Vokáč, Miroslav
AU  - Pokorný, Petr
AU  - Obradović, Vera
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7489
AB  - Rooftop solar modules are usually held in place by racks or frames that are mechanically attached to a roof structure and/or by heavyweight, ballasted footing mounts. These mounts ensure that the panel system remains in position against wind load. However, mechanical connectors create penetrations into the water-resistant layer of the roof, whereas ballasted footing mounts cause a significant additional load on the load-bearing structure of roof. For these reasons, adhesive connection seems to be a beneficial solution. Acrylic adhesive tapes, marked as VHBTM, may provide sufficient strength, and they have no need for mechanical fasteners or ballast. Acrylic adhesive tapes also provide a comfortable, fast, and efficient bonding process with no curing compared to liquid adhesives. On the other hand, resistance to water at load-bearing joints has not been sufficiently studied yet and could be critical for connections exposed to the outdoor environment. The present study aims at the determination of water resistance and durability of the VHBTM tapes from the GPH series, which are typically used to bond a variety of substrates including many metals. The mechanical properties and failure modes are compared for the specimens before and after a 21-day immersion in water. A significant reduction in strength was observed, depending on the substrate material. The study of chemical changes in the acrylic tape and in its leachate through infrared spectroscopy (FT-IR), X-ray fluorescence, and X-ray diffraction analyses clarified the reduction in mechanical properties. The selected VHBTM tape demonstrated strong resistance to the effects of water. However, the overall strength of the joint after immersion was significantly impacted by the decrease in adhesion to a specific substrate.
PB  - MDPI
T2  - Buildings
T1  - Water Resistance of Acrylic Adhesive Tapes for Rooftop Fastening
IS  - 6
SP  - 1636
VL  - 14
DO  - 10.3390/buildings14061636
ER  - 

@article{
author = "Machalická, Klára V. and Sejkot, Petr and Vokáč, Miroslav and Pokorný, Petr and Obradović, Vera",
year = "2024",
abstract = "Rooftop solar modules are usually held in place by racks or frames that are mechanically attached to a roof structure and/or by heavyweight, ballasted footing mounts. These mounts ensure that the panel system remains in position against wind load. However, mechanical connectors create penetrations into the water-resistant layer of the roof, whereas ballasted footing mounts cause a significant additional load on the load-bearing structure of roof. For these reasons, adhesive connection seems to be a beneficial solution. Acrylic adhesive tapes, marked as VHBTM, may provide sufficient strength, and they have no need for mechanical fasteners or ballast. Acrylic adhesive tapes also provide a comfortable, fast, and efficient bonding process with no curing compared to liquid adhesives. On the other hand, resistance to water at load-bearing joints has not been sufficiently studied yet and could be critical for connections exposed to the outdoor environment. The present study aims at the determination of water resistance and durability of the VHBTM tapes from the GPH series, which are typically used to bond a variety of substrates including many metals. The mechanical properties and failure modes are compared for the specimens before and after a 21-day immersion in water. A significant reduction in strength was observed, depending on the substrate material. The study of chemical changes in the acrylic tape and in its leachate through infrared spectroscopy (FT-IR), X-ray fluorescence, and X-ray diffraction analyses clarified the reduction in mechanical properties. The selected VHBTM tape demonstrated strong resistance to the effects of water. However, the overall strength of the joint after immersion was significantly impacted by the decrease in adhesion to a specific substrate.",
publisher = "MDPI",
journal = "Buildings",
title = "Water Resistance of Acrylic Adhesive Tapes for Rooftop Fastening",
number = "6",
pages = "1636",
volume = "14",
doi = "10.3390/buildings14061636"
}

Machalická, K. V., Sejkot, P., Vokáč, M., Pokorný, P.,& Obradović, V.. (2024). Water Resistance of Acrylic Adhesive Tapes for Rooftop Fastening. in Buildings
MDPI., 14(6), 1636.
https://doi.org/10.3390/buildings14061636

Machalická KV, Sejkot P, Vokáč M, Pokorný P, Obradović V. Water Resistance of Acrylic Adhesive Tapes for Rooftop Fastening. in Buildings. 2024;14(6):1636.
doi:10.3390/buildings14061636 .

Machalická, Klára V., Sejkot, Petr, Vokáč, Miroslav, Pokorný, Petr, Obradović, Vera, "Water Resistance of Acrylic Adhesive Tapes for Rooftop Fastening" in Buildings, 14, no. 6 (2024):1636,
https://doi.org/10.3390/buildings14061636 . .

TY  - JOUR
AU  - Obradović, Vera
AU  - Sejkot, Petr
AU  - Zabloudil, Adam
AU  - Machalická, Klára V.
AU  - Vokáč, Miroslav
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7320
AB  - Kevlar fibers are widely used for industrial and military purposes due to their remarkable mechanical properties, such as their high tenacity and high strength-to-weight ratio. In this study, two-layered Kevlar composite specimens were impregnated with 10 wt.% poly (vinyl butyral)/ethanol solution which contained TiO2 nanoparticles as reinforcement. The concentrations of the nanoparticles were 1 wt.% or 2 wt.% with respect to the poly (vinyl butyral), PVB. The single-axial tensile test and three-point bending test of the Kevlar/PVB composites have been performed according to the ASTM D 3039 and ASTM D 790-03 standards, respectively. The tensile and bending properties of the dry and wet Kevlar/PVB composite specimens after a 56-day immersion are examined in this work. Upon the addition of the 2 wt.% TiO2 nanoparticles, the tensile strength and modulus of the dry specimens without reinforcement were increased by 39.8% and 24.3%, respectively. All the submerged specimens’ tensile and flexural property values were lower than those of the dry specimens. After comparing the wet composite specimens to their dry counterparts, the percentage decrease in tensile strength was approximately 20%. The wet Kevlar/PVB specimens with no TiO2 reinforcement showed the greatest reduction in bending strength, 61.4% less than for the dry Kevlar/PVB specimens, due to the degradation of the PVB matrix. In addition, a numerical simulation of the three-point bending test was carried out in Abaqus.
PB  - MDPI
T2  - Buildings
T1  - Degradation Effect of Moisture on Mechanical Properties of Kevlar/PVB Composites with TiO2 Nanoparticles
IS  - 2
SP  - 409
VL  - 14
DO  - 10.3390/buildings14020409
ER  - 

@article{
author = "Obradović, Vera and Sejkot, Petr and Zabloudil, Adam and Machalická, Klára V. and Vokáč, Miroslav",
year = "2024",
abstract = "Kevlar fibers are widely used for industrial and military purposes due to their remarkable mechanical properties, such as their high tenacity and high strength-to-weight ratio. In this study, two-layered Kevlar composite specimens were impregnated with 10 wt.% poly (vinyl butyral)/ethanol solution which contained TiO2 nanoparticles as reinforcement. The concentrations of the nanoparticles were 1 wt.% or 2 wt.% with respect to the poly (vinyl butyral), PVB. The single-axial tensile test and three-point bending test of the Kevlar/PVB composites have been performed according to the ASTM D 3039 and ASTM D 790-03 standards, respectively. The tensile and bending properties of the dry and wet Kevlar/PVB composite specimens after a 56-day immersion are examined in this work. Upon the addition of the 2 wt.% TiO2 nanoparticles, the tensile strength and modulus of the dry specimens without reinforcement were increased by 39.8% and 24.3%, respectively. All the submerged specimens’ tensile and flexural property values were lower than those of the dry specimens. After comparing the wet composite specimens to their dry counterparts, the percentage decrease in tensile strength was approximately 20%. The wet Kevlar/PVB specimens with no TiO2 reinforcement showed the greatest reduction in bending strength, 61.4% less than for the dry Kevlar/PVB specimens, due to the degradation of the PVB matrix. In addition, a numerical simulation of the three-point bending test was carried out in Abaqus.",
publisher = "MDPI",
journal = "Buildings",
title = "Degradation Effect of Moisture on Mechanical Properties of Kevlar/PVB Composites with TiO2 Nanoparticles",
number = "2",
pages = "409",
volume = "14",
doi = "10.3390/buildings14020409"
}

Obradović, V., Sejkot, P., Zabloudil, A., Machalická, K. V.,& Vokáč, M.. (2024). Degradation Effect of Moisture on Mechanical Properties of Kevlar/PVB Composites with TiO2 Nanoparticles. in Buildings
MDPI., 14(2), 409.
https://doi.org/10.3390/buildings14020409

Obradović V, Sejkot P, Zabloudil A, Machalická KV, Vokáč M. Degradation Effect of Moisture on Mechanical Properties of Kevlar/PVB Composites with TiO2 Nanoparticles. in Buildings. 2024;14(2):409.
doi:10.3390/buildings14020409 .

Obradović, Vera, Sejkot, Petr, Zabloudil, Adam, Machalická, Klára V., Vokáč, Miroslav, "Degradation Effect of Moisture on Mechanical Properties of Kevlar/PVB Composites with TiO2 Nanoparticles" in Buildings, 14, no. 2 (2024):409,
https://doi.org/10.3390/buildings14020409 . .