Zeszyty czasopisma

AHEAD OF PRINT

Tom 40 (2022): Zeszyt 2 (August 2022)

Tom 40 (2022): Zeszyt 1 (March 2022)

Tom 39 (2021): Zeszyt 4 (December 2021)

Tom 39 (2021): Zeszyt 3 (September 2021)

Tom 39 (2021): Zeszyt 2 (June 2021)

Tom 39 (2021): Zeszyt 1 (March 2021)

Tom 38 (2020): Zeszyt 4 (December 2020)

Tom 38 (2020): Zeszyt 3 (September 2020)

Tom 38 (2020): Zeszyt 2 (June 2020)

Tom 38 (2020): Zeszyt 1 (March 2020)

Tom 37 (2019): Zeszyt 4 (December 2019)

Tom 37 (2019): Zeszyt 3 (September 2019)

Tom 37 (2019): Zeszyt 2 (June 2019)

Tom 37 (2019): Zeszyt 1 (March 2019)

Tom 36 (2018): Zeszyt 4 (December 2018)

Tom 36 (2018): Zeszyt 3 (September 2018)

Tom 36 (2018): Zeszyt 2 (June 2018)

Tom 36 (2018): Zeszyt 1 (March 2018)

Tom 35 (2017): Zeszyt 4 (December 2017)

Tom 35 (2017): Zeszyt 3 (October 2017)

Tom 35 (2017): Zeszyt 2 (July 2017)

Tom 35 (2017): Zeszyt 1 (March 2017)

Tom 34 (2016): Zeszyt 4 (December 2016)

Tom 34 (2016): Zeszyt 3 (September 2016)

Tom 34 (2016): Zeszyt 2 (June 2016)

Tom 34 (2016): Zeszyt 1 (March 2016)

Tom 33 (2015): Zeszyt 4 (December 2015)

Tom 33 (2015): Zeszyt 3 (September 2015)

Tom 33 (2015): Zeszyt 2 (June 2015)

Tom 33 (2015): Zeszyt 1 (March 2015)

Tom 32 (2014): Zeszyt 4 (December 2014)

Tom 32 (2014): Zeszyt 3 (September 2014)

Tom 32 (2014): Zeszyt 2 (June 2014)

Tom 32 (2014): Zeszyt 1 (January 2014)

Tom 31 (2013): Zeszyt 4 (October 2013)

Tom 31 (2013): Zeszyt 3 (August 2013)

Tom 31 (2013): Zeszyt 2 (April 2013)

Tom 31 (2013): Zeszyt 1 (January 2013)

Tom 30 (2012): Zeszyt 4 (December 2012)

Tom 30 (2012): Zeszyt 3 (September 2012)

Tom 30 (2012): Zeszyt 2 (June 2012)

Tom 30 (2012): Zeszyt 1 (March 2012)

Tom 29 (2011): Zeszyt 4 (December 2011)

Tom 29 (2011): Zeszyt 3 (September 2011)

Tom 29 (2011): Zeszyt 2 (June 2011)

Tom 29 (2011): Zeszyt 1 (March 2011)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
2083-134X
Pierwsze wydanie
16 Apr 2011
Częstotliwość wydawania
4 razy w roku
Języki
Angielski

Wyszukiwanie

Tom 40 (2022): Zeszyt 2 (August 2022)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
2083-134X
Pierwsze wydanie
16 Apr 2011
Częstotliwość wydawania
4 razy w roku
Języki
Angielski

Wyszukiwanie

10 Artykułów
Otwarty dostęp

Studying CdS:In green phosphor's impacts on white-light emitting diode with higher luminous flux

Data publikacji: 07 Sep 2022
Zakres stron: 159 - 169

Abstrakt

Abstract

A lumen efficiency (LE) simulation model with the Monte Carlo method is introduced to the white-light-emitting diode devices that utilize the red LED (light-emitting diode) dyes instead of red-emitting phosphors (R-WLEDs). By simulating this model, the desirable spectrum-related indices and photometric efficiencies, which are adequate for superior chromatic consistency (or Rf > 97), can be accomplished for R-WLEDs under the correlated color temperature (CCT) range of 5000–8000 K. The structure of the R-LED has LEDs in red and blue colors (650 nm and 448 nm) combined with phosphors possessing yellow and green emissions (586 nm and 507 nm). In comparison with pc-WLEDs (WLEDs operating with conversion phosphors) and QD-WLEDs (WLED devices with quantum dots), pc/R-WLED devices could present its outperformance to the others and become a promising way to achieve remarkable chromatic generation, particularly under the condition of small color temperature limit, and act as a substitute for the pc-WLED devices.

Słowa kluczowe

  • WLEDs
  • double-layer phosphor
  • Monte Carlo theory
  • color homogeneity
  • luminous flux
Otwarty dostęp

Preparation of rGO/ZnO photoanodes and their DSSCs performance

Data publikacji: 07 Sep 2022
Zakres stron: 170 - 180

Abstrakt

Abstract

In this study, we report a mild and controllable preparation method for graphene oxide (GO) and ZnO ultrafine powder, respectively. On this basis, reduced graphene oxide (rGO)/ZnO composite powder for the photoanodes of dye-sensitized solar cells (DSSCs) was synthesized by chemical reduction method. Phase composition, microstructure, chemical structure, conductivity, and specific surface area were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Raman, and Brunauer-Emmett-Teller (BET) method, respectively. Photoelectric performance of DSSCs was studied by the current density-voltage (J-V), electrochemical impedance spectra (EIS) photoelectric test system. As rGO possesses higher adsorption capacity and excellent conductivity, hence it may effectively promote separation of electrons and holes, transmission ability of electrons and holes, and utilization of the light. By contrast, the as-synthesized zinc oxide (ZnO) may increase adsorption capacity of dye molecules, so photoelectric conversion efficiency (PCE) of the solar cells is increased by means of synergistic effects. When adding rGO in the rGO/ZnO composite powder at 1.25 wt%, PCE reaches to 6.27%, an increase of 20.6% more than that of pure ZnO as the photoanode.

Słowa kluczowe

  • improved Hummers method
  • GO
  • rGO/ZnO photoanodes
  • photoelectric performance
Otwarty dostęp

Features of the hot recycling method used to repair asphalt concrete pavements

Data publikacji: 07 Sep 2022
Zakres stron: 181 - 195

Abstrakt

Abstract

The recycling methods used in the construction and repairing of asphalt concrete pavements are being constantly improved, and the improvements mostly fall under one of the following common avenues of innovation: developing new binders based on bitumen and cement; developing new varieties of asphalt concrete and other materials having an equivalent utility and function; and developing additives that can be used in the production of new types of binders that can enhance the performance properties of the pavements. This article aims to develop the composition and determine the physical-mechanical and structural-rheological properties of asphalt concrete reclaimed by the hot recycling method and reinforced by fiber of fly ash from thermal power plants (TPP). The author of this article developed a mechanism for the interaction between fiber and bitumen in asphalt binder and acquired an optimum composition of hot granular asphalt concrete. During the research, the author evaluated the utility of fiber used as an additive in reclaimed asphalt concrete, studied its effect on the properties of hot reclaimed asphalt concrete, and examined the technological and performance properties and durability of the material obtained. The fiber of fly ash used in the hot recycling method made it possible to reduce the cost and ensure the high quality and durability of the structural layer of road pavement. Our experiments with analyses of the obtained composition indicated that employing it in the construction of the structural layer of road payment would result in superior structural integrity. Hot recycling made it possible to obtain thick bound layers characterized by the homogeneity of the material. For the first time, the author studied the effect of using fiber of fly ash from Chinese TPP in hot reclaimed asphalt concrete, and the results have proved the rationality of using this composition.

Słowa kluczowe

  • hot regeneration
  • coal combustion product
  • fiber
  • thermal profiling
  • asphalt concrete properties
Otwarty dostęp

Study of synthesis parameters on the physical properties and morphology of smart PNIPAAm hydrogels

Data publikacji: 13 Sep 2022
Zakres stron: 196 - 205

Abstrakt

Abstract

Bone loss is common in human old age and new materials that promote bone regeneration are an active line of research. In the present work, seven smart hydrogels based on PNIPAAm were synthesized with the prospective to be used in tissue engineering as a scaffold for bone growth. By changing the stoichiometric concentrations of the reagents and the synthesis parameters, hydrogels with different physical properties and morphology were obtained. Swelling, degradation properties, and crystallinity were analyzed. Physical properties were characterized using 1H-NMR, FTIR, and TGA. The results showed that the swelling degree (degree of mass expansion) varied at room temperature from 1,400% for less rigid hydrogels to 550% for stiffer hydrogels. With heating to body temperature, swelling decreases to 300% and 200%, respectively. The samples presented three-dimensional morphology, but they acquired different structures according to the magnetic stirring during the synthesis process. The crosslink and initiator concentrations have an important effect on the polymeric structure and thermal stability of the hydrogels. The PNIPAAm synthesized using 8.9 and 15.7 mol % of MBA are the most promising compounds to be used in the future as a scaffold for biomedical applications due to their high thermal stability, satisfactory 3D surface morphology, and shrinking-swelling property.

Słowa kluczowe

  • Smart hydrogels
  • PNIPAAm
  • biomaterials
  • polymer gels
  • synthesis
Otwarty dostęp

Production of pumice-containing nanofibers by electrospinning technique

Data publikacji: 20 Sep 2022
Zakres stron: 206 - 213

Abstrakt

Abstract

The scope of the study involves identifying the optimal means to effectively use the electrospinning technique to obtain pumice-containing nanofibers. Nanofiber containing pumice in a solution was electrospun to obtain smooth, cylindrical, bead-free, and ultrafine nanomaterials.

The study also analyzed the molecular [Fourier transform infrared spectroscopy (FTIR)], thermal [differential scanning calorimetry (DSC)], zeta potential, size, polydispersity index [dynamic light scattering (DLS)], and surface [scanning electron microscope (SEM)] parameters of the pumice-containing nanofibers having JP6 (applied voltage: 6 kV) and JP12 (12 kV) properties. While the distance (10 cm), flow rate (0.8 mL/h), and other parameters of the electrospinning process were fixed, two different voltages were applied to obtain the pumice-containing nanofiber. The average diameter of the nanoencapsulated pumice produced at 6 kV was defined as 98.6 nm in gelatin nanomats with 31.8 nm. The average diameter of the nanocapsule pumice produced under a 12 kV voltage was found to be 85.8 nm, and the average diameter of the nanomats (non–nanoencapsulated) was 35.2 nm. The average zeta potential values of the pumice-containing nanofiber were also determined in the nanosize range. The JP6 and JP12 PDI values were determined as 0.165 and 0.566, respectively. Peaks characteristic of pumices as defined in the literature were observed in the FTIR results, while DSC analysis results revealed strong endo- and exothermic peaks. As a result of this study, it has been proved that pumice can be reduced to nanosize with the electrospinning technique and it is nanoencapsulated in nanofiber. When the obtained pumice-containing nanofiber was examined, it was determined that the surface area of the nanofiber was large and resistant to thermal heat.

Słowa kluczowe

  • nanotechnology
  • nanofiber
  • pumice
  • characterization
  • fabrication parameters
  • electrospinning
Otwarty dostęp

Effect of silane coating surface treatment on friction and wear properties of carbon fiber/PI composites

Data publikacji: 20 Sep 2022
Zakres stron: 214 - 222

Abstrakt

Abstract

PAN-based carbon fiber was surface-modified with silane coating, and a composite material was prepared using a PI resin as a matrix. The structure and surface properties of carbon fibers were studied by means of X-ray photoelectron spectroscopy (XPS) and SEM. The tensile strength of the composite was measured by a tensile tester, and the friction properties of the composite were measured by a micro-nano mechanics comprehensive test system. The results show that treatment with silane coating can improve the surface roughness and chemical activity of carbon fiber, improve the interface between carbon fiber and PI resin matrix, and improve the tensile strength and wear rate of the composite.

Słowa kluczowe

  • mechanical
  • PI
  • CF
  • friction
  • SEM
Otwarty dostęp

Electrical resistance and self-sensing properties of pressure-sensitive materials with graphite filler in Kuralon fiber concrete

Data publikacji: 20 Sep 2022
Zakres stron: 223 - 239

Abstrakt

Abstract

This study aimed to investigate conductivity behavior of concrete containing graphite and its sensitivity to the effects of pressure. Graphite powder was added to concrete to replace partial cement (4 wt.%, 8 wt.%, 12 wt.%, and 16 wt.%) as conductive fillers with a water-to-cementitious ratio of 0.45. Specimens with 0.5 vol.% Kuralon fibers were treated to enhance the performance of self-sensing properties to investigate the influence of graphite and fiber contents on electrical resistivities. The relationship between the axial load and changes in resistivity was determined using cyclic loading tests, indicating the existence and development of internal cracking in concrete. The results indicated that the compressive strength presented a linear decline proportional to the addition of graphite. Specimens with 8% graphite reached the lower bound of self-sensing properties, and with an increase in the amount of graphite, resistivity gradually decreased. In the cyclic loading tests, specimens containing >8% graphite were able to better reflect the relationship between loading and resistivity. Kuralon fibers in concrete had further improvement in resistance and self-sensing properties. In inclusion, the mixture with 8% graphite provided the best self-sensing properties to warn for preventing the effects of cracking, as well as achieved better mechanical properties.

Słowa kluczowe

  • pressure-sensitive materials
  • graphite powders
  • resistivity change rate
  • cyclic loading test
Otwarty dostęp

Optimization of joining HDPE rods by continuous drive friction welding

Data publikacji: 13 Oct 2022
Zakres stron: 240 - 256

Abstrakt

Abstract

Continuous drive friction welding (CDFW) is a solid-state joining procedure that can be used to join various similar and dissimilar materials. High-density polyethylene (HDPE) is a thermoplastic that can replace many traditional materials. Utilizing experimental design procedures such as response surface method (RSM) is a reliable approach for determining the most significant process parameters and optimizing the desired responses. The current study employed an RSM experimental design to investigate the effects of the process parameters for welding HDPE rods using CDFW. The design evaluated the process parameters and three outcome responses: the maximum welding temperature, the axial shortening, and the tensile strength (TS). The combination of the three responses can allow achieving high-efficiency welds. The results showed that it was possible to achieve high-efficiency welds while maintaining axial shortening and controlling temperature. A TS >65% of the parent material's strength with an axial shortening of <3 mm was achieved.

Słowa kluczowe

  • continuous drive friction welding
  • RSM
  • HDPE
  • welding temperature
  • axial shortening
  • tensile strength
Otwarty dostęp

Evaluation of CO2 adsorption capacity with a nano-CaO synthesized by chemical combustion/ball milling

Data publikacji: 23 Oct 2022
Zakres stron: 257 - 269

Abstrakt

Abstract

The adsorption of CO2 on a nano-calcium oxide (nano-CaO) adsorbent was investigated under different conditions of temperature and supply pressure, considering kinetic, isotherm, and thermodynamic parameters. CaO is a crystalline material with a high surface area and nanosized particles with high porosity, which showed rapid initial CO2 adsorption rates in the moderate temperature range studied. The adsorption was well described by the pseudo-second-order and the intraparticle diffusion kinetic models. The Langmuir isotherm model fitted the experimental data well, indicating a monolayer-type process. The thermodynamic parameters revealed that the CO2/nano-CaO adsorption was endothermic, not spontaneous, and proceeded via physical and chemical processes. The activation energy value confirmed that the mechanism involved is a chemical process. In addition, the nano-CaO adsorbent could be regenerated five times without any significant loss of performance or properties. All the obtained results reveal that this porous nanoadsorbent has huge potential to be applied for CO2-capture technologies on a large scale.

Słowa kluczowe

  • nano-CaO adsorbent
  • CO adsorption
  • kinetics
  • isotherm
  • thermodynamics
Otwarty dostęp

Development of building materials based on a high content of fly ash and polycondensation products from Chinese heat and power plants

Data publikacji: 24 Nov 2022
Zakres stron: 270 - 288

Abstrakt

Abstract

The addition of fly ash from thermal power plants (TPP) and chemical additives, such as polycondensation products of acetone and formaldehyde, is an effective and economical method for increasing the strength and durability of building materials, in particular concrete. Fly ash added to the concrete and mortars at 10%–15% does not reduce their technical properties, while polycondensation products of acetone and formaldehyde plasticize and accelerate the hardening process of concrete. The study aims to substantiate the possibility of obtaining concrete on dense aggregates with a high content of fly ash through the use of polycondensation products of acetone and formaldehyde as additives, which are highly soluble in water and polyfunctional. The strength indicators were determined using standard methods. The study has shown quantitative changes in the properties of the fly ash-concrete mixture, improvement of its physical and technical characteristics, and durability of the fly ash concrete with the addition of polycondensation products of acetone and formaldehyde. In the present study, the authors determine the effect of fly ash addition on the properties of a concrete mixture, as well as the maximum possible content of fly ash that can be added to concrete to maximize certain properties required of the mixture; additionally, the same action is conducted with the addition of polycondensation products of acetone and formaldehyde concomitant with the addition of fly ash.

Słowa kluczowe

  • acetone-formaldehyde resins
  • ash-and-slag mixture
  • concrete properties
  • fly ash
  • mineral additive
10 Artykułów
Otwarty dostęp

Studying CdS:In green phosphor's impacts on white-light emitting diode with higher luminous flux

Data publikacji: 07 Sep 2022
Zakres stron: 159 - 169

Abstrakt

Abstract

A lumen efficiency (LE) simulation model with the Monte Carlo method is introduced to the white-light-emitting diode devices that utilize the red LED (light-emitting diode) dyes instead of red-emitting phosphors (R-WLEDs). By simulating this model, the desirable spectrum-related indices and photometric efficiencies, which are adequate for superior chromatic consistency (or Rf > 97), can be accomplished for R-WLEDs under the correlated color temperature (CCT) range of 5000–8000 K. The structure of the R-LED has LEDs in red and blue colors (650 nm and 448 nm) combined with phosphors possessing yellow and green emissions (586 nm and 507 nm). In comparison with pc-WLEDs (WLEDs operating with conversion phosphors) and QD-WLEDs (WLED devices with quantum dots), pc/R-WLED devices could present its outperformance to the others and become a promising way to achieve remarkable chromatic generation, particularly under the condition of small color temperature limit, and act as a substitute for the pc-WLED devices.

Słowa kluczowe

  • WLEDs
  • double-layer phosphor
  • Monte Carlo theory
  • color homogeneity
  • luminous flux
Otwarty dostęp

Preparation of rGO/ZnO photoanodes and their DSSCs performance

Data publikacji: 07 Sep 2022
Zakres stron: 170 - 180

Abstrakt

Abstract

In this study, we report a mild and controllable preparation method for graphene oxide (GO) and ZnO ultrafine powder, respectively. On this basis, reduced graphene oxide (rGO)/ZnO composite powder for the photoanodes of dye-sensitized solar cells (DSSCs) was synthesized by chemical reduction method. Phase composition, microstructure, chemical structure, conductivity, and specific surface area were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Raman, and Brunauer-Emmett-Teller (BET) method, respectively. Photoelectric performance of DSSCs was studied by the current density-voltage (J-V), electrochemical impedance spectra (EIS) photoelectric test system. As rGO possesses higher adsorption capacity and excellent conductivity, hence it may effectively promote separation of electrons and holes, transmission ability of electrons and holes, and utilization of the light. By contrast, the as-synthesized zinc oxide (ZnO) may increase adsorption capacity of dye molecules, so photoelectric conversion efficiency (PCE) of the solar cells is increased by means of synergistic effects. When adding rGO in the rGO/ZnO composite powder at 1.25 wt%, PCE reaches to 6.27%, an increase of 20.6% more than that of pure ZnO as the photoanode.

Słowa kluczowe

  • improved Hummers method
  • GO
  • rGO/ZnO photoanodes
  • photoelectric performance
Otwarty dostęp

Features of the hot recycling method used to repair asphalt concrete pavements

Data publikacji: 07 Sep 2022
Zakres stron: 181 - 195

Abstrakt

Abstract

The recycling methods used in the construction and repairing of asphalt concrete pavements are being constantly improved, and the improvements mostly fall under one of the following common avenues of innovation: developing new binders based on bitumen and cement; developing new varieties of asphalt concrete and other materials having an equivalent utility and function; and developing additives that can be used in the production of new types of binders that can enhance the performance properties of the pavements. This article aims to develop the composition and determine the physical-mechanical and structural-rheological properties of asphalt concrete reclaimed by the hot recycling method and reinforced by fiber of fly ash from thermal power plants (TPP). The author of this article developed a mechanism for the interaction between fiber and bitumen in asphalt binder and acquired an optimum composition of hot granular asphalt concrete. During the research, the author evaluated the utility of fiber used as an additive in reclaimed asphalt concrete, studied its effect on the properties of hot reclaimed asphalt concrete, and examined the technological and performance properties and durability of the material obtained. The fiber of fly ash used in the hot recycling method made it possible to reduce the cost and ensure the high quality and durability of the structural layer of road pavement. Our experiments with analyses of the obtained composition indicated that employing it in the construction of the structural layer of road payment would result in superior structural integrity. Hot recycling made it possible to obtain thick bound layers characterized by the homogeneity of the material. For the first time, the author studied the effect of using fiber of fly ash from Chinese TPP in hot reclaimed asphalt concrete, and the results have proved the rationality of using this composition.

Słowa kluczowe

  • hot regeneration
  • coal combustion product
  • fiber
  • thermal profiling
  • asphalt concrete properties
Otwarty dostęp

Study of synthesis parameters on the physical properties and morphology of smart PNIPAAm hydrogels

Data publikacji: 13 Sep 2022
Zakres stron: 196 - 205

Abstrakt

Abstract

Bone loss is common in human old age and new materials that promote bone regeneration are an active line of research. In the present work, seven smart hydrogels based on PNIPAAm were synthesized with the prospective to be used in tissue engineering as a scaffold for bone growth. By changing the stoichiometric concentrations of the reagents and the synthesis parameters, hydrogels with different physical properties and morphology were obtained. Swelling, degradation properties, and crystallinity were analyzed. Physical properties were characterized using 1H-NMR, FTIR, and TGA. The results showed that the swelling degree (degree of mass expansion) varied at room temperature from 1,400% for less rigid hydrogels to 550% for stiffer hydrogels. With heating to body temperature, swelling decreases to 300% and 200%, respectively. The samples presented three-dimensional morphology, but they acquired different structures according to the magnetic stirring during the synthesis process. The crosslink and initiator concentrations have an important effect on the polymeric structure and thermal stability of the hydrogels. The PNIPAAm synthesized using 8.9 and 15.7 mol % of MBA are the most promising compounds to be used in the future as a scaffold for biomedical applications due to their high thermal stability, satisfactory 3D surface morphology, and shrinking-swelling property.

Słowa kluczowe

  • Smart hydrogels
  • PNIPAAm
  • biomaterials
  • polymer gels
  • synthesis
Otwarty dostęp

Production of pumice-containing nanofibers by electrospinning technique

Data publikacji: 20 Sep 2022
Zakres stron: 206 - 213

Abstrakt

Abstract

The scope of the study involves identifying the optimal means to effectively use the electrospinning technique to obtain pumice-containing nanofibers. Nanofiber containing pumice in a solution was electrospun to obtain smooth, cylindrical, bead-free, and ultrafine nanomaterials.

The study also analyzed the molecular [Fourier transform infrared spectroscopy (FTIR)], thermal [differential scanning calorimetry (DSC)], zeta potential, size, polydispersity index [dynamic light scattering (DLS)], and surface [scanning electron microscope (SEM)] parameters of the pumice-containing nanofibers having JP6 (applied voltage: 6 kV) and JP12 (12 kV) properties. While the distance (10 cm), flow rate (0.8 mL/h), and other parameters of the electrospinning process were fixed, two different voltages were applied to obtain the pumice-containing nanofiber. The average diameter of the nanoencapsulated pumice produced at 6 kV was defined as 98.6 nm in gelatin nanomats with 31.8 nm. The average diameter of the nanocapsule pumice produced under a 12 kV voltage was found to be 85.8 nm, and the average diameter of the nanomats (non–nanoencapsulated) was 35.2 nm. The average zeta potential values of the pumice-containing nanofiber were also determined in the nanosize range. The JP6 and JP12 PDI values were determined as 0.165 and 0.566, respectively. Peaks characteristic of pumices as defined in the literature were observed in the FTIR results, while DSC analysis results revealed strong endo- and exothermic peaks. As a result of this study, it has been proved that pumice can be reduced to nanosize with the electrospinning technique and it is nanoencapsulated in nanofiber. When the obtained pumice-containing nanofiber was examined, it was determined that the surface area of the nanofiber was large and resistant to thermal heat.

Słowa kluczowe

  • nanotechnology
  • nanofiber
  • pumice
  • characterization
  • fabrication parameters
  • electrospinning
Otwarty dostęp

Effect of silane coating surface treatment on friction and wear properties of carbon fiber/PI composites

Data publikacji: 20 Sep 2022
Zakres stron: 214 - 222

Abstrakt

Abstract

PAN-based carbon fiber was surface-modified with silane coating, and a composite material was prepared using a PI resin as a matrix. The structure and surface properties of carbon fibers were studied by means of X-ray photoelectron spectroscopy (XPS) and SEM. The tensile strength of the composite was measured by a tensile tester, and the friction properties of the composite were measured by a micro-nano mechanics comprehensive test system. The results show that treatment with silane coating can improve the surface roughness and chemical activity of carbon fiber, improve the interface between carbon fiber and PI resin matrix, and improve the tensile strength and wear rate of the composite.

Słowa kluczowe

  • mechanical
  • PI
  • CF
  • friction
  • SEM
Otwarty dostęp

Electrical resistance and self-sensing properties of pressure-sensitive materials with graphite filler in Kuralon fiber concrete

Data publikacji: 20 Sep 2022
Zakres stron: 223 - 239

Abstrakt

Abstract

This study aimed to investigate conductivity behavior of concrete containing graphite and its sensitivity to the effects of pressure. Graphite powder was added to concrete to replace partial cement (4 wt.%, 8 wt.%, 12 wt.%, and 16 wt.%) as conductive fillers with a water-to-cementitious ratio of 0.45. Specimens with 0.5 vol.% Kuralon fibers were treated to enhance the performance of self-sensing properties to investigate the influence of graphite and fiber contents on electrical resistivities. The relationship between the axial load and changes in resistivity was determined using cyclic loading tests, indicating the existence and development of internal cracking in concrete. The results indicated that the compressive strength presented a linear decline proportional to the addition of graphite. Specimens with 8% graphite reached the lower bound of self-sensing properties, and with an increase in the amount of graphite, resistivity gradually decreased. In the cyclic loading tests, specimens containing >8% graphite were able to better reflect the relationship between loading and resistivity. Kuralon fibers in concrete had further improvement in resistance and self-sensing properties. In inclusion, the mixture with 8% graphite provided the best self-sensing properties to warn for preventing the effects of cracking, as well as achieved better mechanical properties.

Słowa kluczowe

  • pressure-sensitive materials
  • graphite powders
  • resistivity change rate
  • cyclic loading test
Otwarty dostęp

Optimization of joining HDPE rods by continuous drive friction welding

Data publikacji: 13 Oct 2022
Zakres stron: 240 - 256

Abstrakt

Abstract

Continuous drive friction welding (CDFW) is a solid-state joining procedure that can be used to join various similar and dissimilar materials. High-density polyethylene (HDPE) is a thermoplastic that can replace many traditional materials. Utilizing experimental design procedures such as response surface method (RSM) is a reliable approach for determining the most significant process parameters and optimizing the desired responses. The current study employed an RSM experimental design to investigate the effects of the process parameters for welding HDPE rods using CDFW. The design evaluated the process parameters and three outcome responses: the maximum welding temperature, the axial shortening, and the tensile strength (TS). The combination of the three responses can allow achieving high-efficiency welds. The results showed that it was possible to achieve high-efficiency welds while maintaining axial shortening and controlling temperature. A TS >65% of the parent material's strength with an axial shortening of <3 mm was achieved.

Słowa kluczowe

  • continuous drive friction welding
  • RSM
  • HDPE
  • welding temperature
  • axial shortening
  • tensile strength
Otwarty dostęp

Evaluation of CO2 adsorption capacity with a nano-CaO synthesized by chemical combustion/ball milling

Data publikacji: 23 Oct 2022
Zakres stron: 257 - 269

Abstrakt

Abstract

The adsorption of CO2 on a nano-calcium oxide (nano-CaO) adsorbent was investigated under different conditions of temperature and supply pressure, considering kinetic, isotherm, and thermodynamic parameters. CaO is a crystalline material with a high surface area and nanosized particles with high porosity, which showed rapid initial CO2 adsorption rates in the moderate temperature range studied. The adsorption was well described by the pseudo-second-order and the intraparticle diffusion kinetic models. The Langmuir isotherm model fitted the experimental data well, indicating a monolayer-type process. The thermodynamic parameters revealed that the CO2/nano-CaO adsorption was endothermic, not spontaneous, and proceeded via physical and chemical processes. The activation energy value confirmed that the mechanism involved is a chemical process. In addition, the nano-CaO adsorbent could be regenerated five times without any significant loss of performance or properties. All the obtained results reveal that this porous nanoadsorbent has huge potential to be applied for CO2-capture technologies on a large scale.

Słowa kluczowe

  • nano-CaO adsorbent
  • CO adsorption
  • kinetics
  • isotherm
  • thermodynamics
Otwarty dostęp

Development of building materials based on a high content of fly ash and polycondensation products from Chinese heat and power plants

Data publikacji: 24 Nov 2022
Zakres stron: 270 - 288

Abstrakt

Abstract

The addition of fly ash from thermal power plants (TPP) and chemical additives, such as polycondensation products of acetone and formaldehyde, is an effective and economical method for increasing the strength and durability of building materials, in particular concrete. Fly ash added to the concrete and mortars at 10%–15% does not reduce their technical properties, while polycondensation products of acetone and formaldehyde plasticize and accelerate the hardening process of concrete. The study aims to substantiate the possibility of obtaining concrete on dense aggregates with a high content of fly ash through the use of polycondensation products of acetone and formaldehyde as additives, which are highly soluble in water and polyfunctional. The strength indicators were determined using standard methods. The study has shown quantitative changes in the properties of the fly ash-concrete mixture, improvement of its physical and technical characteristics, and durability of the fly ash concrete with the addition of polycondensation products of acetone and formaldehyde. In the present study, the authors determine the effect of fly ash addition on the properties of a concrete mixture, as well as the maximum possible content of fly ash that can be added to concrete to maximize certain properties required of the mixture; additionally, the same action is conducted with the addition of polycondensation products of acetone and formaldehyde concomitant with the addition of fly ash.

Słowa kluczowe

  • acetone-formaldehyde resins
  • ash-and-slag mixture
  • concrete properties
  • fly ash
  • mineral additive

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