Electric-Potential-Driven Pressure-Sensing Observation in New Hollow Radial ZnO and Their Heterostructure with Carbon

Many applications demonstrated for ZnO desire a high dielectric constant and quickly induced polarization properties with frequency. We present new hollow radial zinc oxide nanostructure and carbon-decorated hollow ZnO heterostructures, which greatly influence the dielectric and capacitive pressure-sensing properties after integrating in polyvinyldine fluoride matrix. The hollow zinc oxide nanostructure was realized by using a simple and cost-effective ambient temperature template-free synthesis process. Crystal structure was investigated by using X-ray diffraction and Raman spectroscopy and then correlated with high-resolution transmission electron microscopy, which reveals buckling of lattice fringes. Mimicking the wurzite structure of ZnO, the developed carbon-decorated hollow radial ZnO improved the dielectric constant ∼140 at 100 Hz and reinforcing efficiency >4 times that of hollow radial ZnO because of strong interfacial polarization. We demonstrated a simple design, fabrication, and testing of flexible polymer composite pressure-sensing device by using such fascinating nanostructures. The capacitive pressure-sensing response is calculated to be 35 times (≤0.002 MPa) and 24 times (≤0.006 MPa) higher than that of the pristine PVDF-based device after poling under corona. Furthermore, the developed devices showed significant capacitive change upon bending because of the displacement of electrodes and change in spacing between the fillers in the polymer matrix

Adsorption of Charge Carriers on Radial Zinc Oxide and the Study of Their Stability and Dielectric Behavior in Poly(vinylidene fluoride)

Radial zinc oxide (ZnO) was prepared using a new user-friendly chemical process, and the surface was modified by adsorbing polyaniline (PANI) as a charge carrier. The modified ZnO (PZnO) was used to prepare poly­(vinylidene fluoride) (PVDF)–PZnO nanocomposites with improved dielectric properties. The structural morphology of the fillers was examined using powder X-ray diffraction and then correlated with observations from high-resolution transmission electron microscopy. A new characterization technique was used to study the maximum adsorption limit by performing solvent relaxation nuclear magnetic resonance experiments, and the results suggested that a maximum of 10% PANI is adsorbed onto the ZnO. The adsorbed PANI acted as an interface and stabilized the ZnO in PVDF solution due to strong interactions between the matrix and fillers. An electron spin resonance (ESR) study was carried out to characterize the spin resonance of ZnO and PZnO. The adsorption of PANI onto ZnO generated charge carriers, and hence, under the influence of a magnetic field, the samples exhibited dissimilar resonance behavior. Dielectric studies of the PVDF–PZnO composites were performed, and the PVDF–ZnO composites and pure PVDF were compared over a wide range of frequencies (0.01 Hz–1 MHz) and temperatures (25–90 °C). The results suggest that the PVDF–7.5PZnO composite showed a significantly improved dielectric constant with a decrease in dielectric loss (0.2), most likely because the adsorption of PANI onto ZnO led to strong interactions between the matrix and fillers and enhanced the interfacial polarization in PVDF

Prediction of Pore Volume Dispersion and Microstructural Characteristics of Concrete Using Image Processing Technique

Concrete has served an essential role in many infrastructural projects. Factors including pore percentage, pore distribution, and cracking affect concrete durability. This research aims to better understand pore size distribution in cement-based materials. Micro-computed tomography (micro-CT) pictures were utilised to characterise the interior structure of specimens without destroying them. The pore dispersion of the specimens was displayed in 3D, utilising the data and imaging techniques collected, and the pore volume dispersion was examined using a volume-based approach. Another way to describe heterogeneous pore features is the chord-length distribution, which was calculated from three-dimensional micro-CT scans and correlated with the traditional method. The collected specimens were subjected to physical and mechanical testing. In addition, image processing techniques were used to conduct the studies. The results showed that the chord-length distribution-based pore size distribution is very successful than the traditional volume-based technique. The acquired data could be used for research and to forecast the characteristics of the materials

Prediction of Pore Volume Dispersion and Microstructural Characteristics of Concrete Using Image Processing Technique

Concrete has served an essential role in many infrastructural projects. Factors including pore percentage, pore distribution, and cracking affect concrete durability. This research aims to better understand pore size distribution in cement-based materials. Micro-computed tomography (micro-CT) pictures were utilised to characterise the interior structure of specimens without destroying them. The pore dispersion of the specimens was displayed in 3D, utilising the data and imaging techniques collected, and the pore volume dispersion was examined using a volume-based approach. Another way to describe heterogeneous pore features is the chord-length distribution, which was calculated from three-dimensional micro-CT scans and correlated with the traditional method. The collected specimens were subjected to physical and mechanical testing. In addition, image processing techniques were used to conduct the studies. The results showed that the chord-length distribution-based pore size distribution is very successful than the traditional volume-based technique. The acquired data could be used for research and to forecast the characteristics of the materials

Experimental Investigation on Geopolymer Concrete with Various Sustainable Mineral Ashes

The aim of this research was to find the best alternative for river sand in concrete. In both geopolymer concrete (GPC) and cement concrete (CC), the fine aggregates are replaced with various sustainable mineral ashes, and mechanical and durability tests are conducted. Specimens for tests were made of M40 grade GPC and CC, with five different soil types as river sand substitute. The materials chosen to replace the river sand are manufactured sand (M-sand), sea sand, copper slag, quarry dust, and limestone sand as 25%, 50%, 75%, and 100%, respectively by weight. GPF50 and CC50 were kept as control mixes for GPC and CC, respectively. The test results of respective concretes are compared with the control mix results. From compressive strength results, M-sand as a fine aggregate had an increase in strength in every replacement level of GPC and CC. Additionally, copper slag is identified with a significant strength reduction in GPC and CC after 25% replacement. Copper slag, quarry dust, and limestone sand in GPC and CC resulted in considerable loss of strength in all replacement levels except for 25% replacement. The cost of GPC and CC is mixed with the selected fine aggregate replacement materials which arrived. Durability and cost analyses are performed for the advisable mixes and control mixes to have a comparison. Durability tests, namely, water absorption and acid tests and water permeability and thermal tests are conducted and discussed. Durability results also indicate a positive signal to mixes with M-sand. The advisable replacement of river sand with each alternative is discussed

Multiferroic Electroactive Polymer Blend/Ferrite Nanocomposite Flexible Films for Cooling Devices

In recent days, the interest toward the development of multicaloric materials for cooling application is increasing, whereas multiferroic materials would be the suitable alternative to the conventional refrigerants. To explore them, the poly(methyl methacrylate)/poly(vinylidenefluoride-co-hexafluoropropylene) (PMMA/PVDF-HFP) blend and PMMA/PVDF-HFP/ZnCuFeO flexible multiferroic nanocomposite films were fabricated by the solution casting method. The structural analyses prove that the strong interfacial interaction between the PMMA/PVDF-HFP blend and the ZnCuFeO (ZCF) through hydroxyl (−OH) and carbonyl group bonding with PVDF-HFP enhanced the thermal stability and suppressed the electroactive β phase from 67 to 62%. Experimental results show that 10 wt % of superparamagnetic ZCF nanoparticles with a particle size of 6.8 nm induced both the magnetocaloric and magnetoelectric effects in a nonmagnetic PMMA/PVDF-HFP ferroelectric matrix at room temperature. A set of isothermal magnetization curves were recorded in the magnetic field strength of 0-40 kOe and a temperature range of 2-400 K. The maximum magnetic entropy changes (ΔS) of −0.69 J·kg K of ZCF nanoparticles and −0.094 J·kg K of PMMA/PVDF-HFP/ZCF nanocomposites showed an interesting table-like flat variation in the temperature range of 100-400 K as a function of the magnetic field. The samples display a large temperature span with a relative cooling power of 293 and 40 J·kg for ZCF and PMMA/PVDF-HFP/ZCF, respectively. The magnetoelectric effect of the PMMA/PVDF-HFP/ZCF composite was proved, but it generated only 1.42 mV/m·Oe in the applied field of 5 kOe. Hence, the entropy change of the present nanocomposite was only due to the magnetocaloric effect, where the magnetoelectric cross-coupling coefficient was negligible. The multicaloric effect could be established if the nanocomposite showed a larger magnetoelectric cross-coupling in addition to the magnetocaloric effect. This approach provides the research findings in functional multiferroic polymer nanocomposites for miniaturized cooling devices.The authors greatly thank the FAPESP Postdoctoral Fellow-ship Process Number 2018/19096-1 and FAPESP thematic project number: 2017/10581-1, São Paulo, Brazil, and FONDECYT Postdoctoral Research Project No.:3 160170, Governmentof Chile,forfinancial assistance

Experimental Investigation and Image Processing to Predict the Properties of Concrete with the Addition of Nano Silica and Rice Husk Ash

The use of the combination of ultrafine rice husk ash (RHA) and nano silica (NS) enhances the compactness of hardened concrete, but there is still a lack of studies that address the effects of NS and RHA on the workability, mechanical properties and pore microstructure of concrete. This study mainly aims to investigate the influence of the pore size distribution in multiphysics concrete model modified by NS and RHA and to determine the workability and mechanical properties of concrete with NS and RHA. In this work, NS and RHA were used as 0, 5, 10, 15 and 20% replacements of ordinary Portland cement (OPC) in concrete grade M20. Concrete mixed with NS and RHA showed improved performance for up to 10% addition of NS and RHA. Further addition of NS and RHA showed a decrease in performance at 7, 14 and 28 days. The decrease in concrete porosity was also found to be up to 10% when adding NS and RHA to cement. Image processing was performed on the cement-based materials to describe the microstructure of the targeted material without damage. The results from the experimental and tomography images were utilized to investigate the concrete microstructure and predict its inner properties.Applied Science, Faculty ofNon UBCCivil Engineering, Department ofReviewedFacult

Multiferroic Electroactive Polymer Blend/Ferrite Nanocomposite Flexible Films for Cooling Devices

In recent days, the interest toward the development of multicaloric materials for cooling application is increasing, whereas multiferroic materials would be the suitable alternative to the conventional refrigerants. To explore them, the poly(methyl methacrylate)/poly(vinylidenefluoride-co-hexafluoropropylene) (PMMA/PVDF-HFP) blend and PMMA/PVDF-HFP/Zn0.5Cu0.5Fe2O4 flexible multiferroic nanocomposite films were fabricated by the solution casting method. The structural analyses prove that the strong interfacial interaction between the PMMA/PVDF-HFP blend and the Zn0.5Cu0.5Fe2O4 (ZCF) through hydroxyl (−OH) and carbonyl group bonding with PVDF-HFP enhanced the thermal stability and suppressed the electroactive β phase from 67 to 62%. Experimental results show that 10 wt % of superparamagnetic ZCF nanoparticles with a particle size of 6.8 nm induced both the magnetocaloric and magnetoelectric effects in a nonmagnetic PMMA/PVDF-HFP ferroelectric matrix at room temperature. A set of isothermal magnetization curves were recorded in the magnetic field strength of 0–40 kOe and a temperature range of 2–400 K. The maximum magnetic entropy changes (ΔSM) of −0.69 J·kg–1 K–1 of ZCF nanoparticles and −0.094 J·kg–1 K–1 of PMMA/PVDF-HFP/ZCF nanocomposites showed an interesting table-like flat variation in the temperature range of 100–400 K as a function of the magnetic field. The samples display a large temperature span with a relative cooling power of 293 and 40 J·kg–1 for ZCF and PMMA/PVDF-HFP/ZCF, respectively. The magnetoelectric effect of the PMMA/PVDF-HFP/ZCF composite was proved, but it generated only 1.42 mV/m·Oe in the applied field of 5 kOe. Hence, the entropy change of the present nanocomposite was only due to the magnetocaloric effect, where the magnetoelectric cross-coupling coefficient was negligible. The multicaloric effect could be established if the nanocomposite showed a larger magnetoelectric cross-coupling in addition to the magnetocaloric effect. This approach provides the research findings in functional multiferroic polymer nanocomposites for miniaturized cooling devices