scholarly journals Assessing Changes in Dielectric Properties Due to Nanomaterials Using a Two-Port Microwave System

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6228
Author(s):  
Mohammed Rahman ◽  
Rachita Lahri ◽  
Syed Ahsan ◽  
Maya Thanou ◽  
Panagiotis Kosmas
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Contrast Enhancement ◽  
Multiwall Carbon Nanotubes ◽  
Glycerol Water ◽  
Microwave System ◽  
Dielectric Contrast ◽  
Microwave Signals ◽  
The Impact

Detecting changes in the dielectric properties of tissues at microwave frequencies can offer simple and cost effective tools for cancer detection. These changes can be enhanced by the use of nanoparticles (NPs) that are characterised by both increased tumour uptake and high dielectric constant. This paper presents a two-port experimental setup to assess the impact of contrast enhancement on microwave signals. The study focuses on carbon nanotubes, as they have been previously shown to induce high microwave dielectric contrast. We investigate multiwall carbon nanotubes (MWNT) and their -OH functionalised version (MWNT-OH) dispersed in tissue phantoms as contrast enhancing NPs, as well as salt (NaCl) solutions as reference mixtures which can be easily dissolved inside water mixtures and thus induce dielectric contrast changes reliably. MWNT and MWNT-OH are characterised by atomic force microscopy, and their dielectric properties are measured when dispersed in 60% glycerol–water mixtures. Salt concentrations between 10 and 50 mg/mL in 60% glycerol mixtures are also studied as homogeneous samples known to affect the dielectric constant. Contrast enhancement is then evaluated using a simplified two-port microwave system to identify the impact on microwave signals with respect to dielectric contrast. Numerical simulations are also conducted to compare results with the experimental findings. Our results suggest that this approach can be used as a reliable method to screen and assess contrast enhancing materials with regards to a microwave system’s ability to detect their impact on a target.

Effect of Functionalized MWCNT on the Mechanical and Dielectric Properties of PMMA Nanocomposites

2018 ◽  
Vol 18 (06) ◽  
pp. 1850035
Author(s):  
Punyapriya Mishra ◽  
Narasingh Deep ◽  
Sagarika Pradhan ◽  
Vikram G. Kamble
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Tensile Strength ◽  
Electron Microscope ◽  
Dielectric Properties ◽  
Conductive Polymer ◽  
Mechanical Tests ◽  
Surface Structures ◽  
Scanning Electron

Carbon nanotubes (CNTs) are widely explained in fundamental blocks of nanotechnology. These CNTs exhibit much greater tensile strength than steel, even almost similar to copper, but they have higher ability to carry much higher currents, they seem to be a magical material with all these mentioned properties. In this paper, an attempt has been made to incorporate this wonder material, CNT, (with varying percentages) in polymeric matrix (Poly methyl methacrylate (PMMA)) to create a new conductive polymer composite. Various mechanical tests were carried out to evaluate its mechanical properties. The dielectric properties such as dielectric loss and dielectric constant were evaluated with the reference of temperature and frequency. The surface structures were analyzed by Scanning Electron Microscope (SEM).

scholarly journals Nanocomposites with Liquid-Like Multiwalled Carbon Nanotubes Dispersed in Epoxy Resin without Solvent Process

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Xi Zhang ◽  
Ya-Ping Zheng ◽  
Rui-Lu Yang ◽  
Hai-Cheng Yang
Keyword(s):  
Carbon Nanotubes ◽  
Ethylene Oxide ◽  
Epoxy Matrix ◽  
Multiwall Carbon Nanotubes ◽  
Multiwalled Carbon ◽  
Free Process ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Poly Propylene ◽  
The Impact

Liquid-like multiwall carbon nanotubes (MWNTs) were prepared with as-received carboxylic MWNTs-COOH and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO) through hydrogen bonding. The sample has liquid-like behavior above 58°C. The MWNTs content is 26.6 wt%. The liquid-like MWNTs nanofluids were incorporated into epoxy matrix with solvent-free process and dispersed well. When the liquid-like MWNTs nanofluids content is up to 1 wt%, the impact toughness of the nanocomposite is 153% higher than the pure epoxy matrix.

scholarly journals Micromorphology and Mechanical and Dielectric Properties of Bismaleimide Composite Modified by Multiwalled Carbon Nanotubes and Polyethersulfone

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Yufei Chen ◽  
Chengbao Geng ◽  
Yang Han ◽  
Mingzhuo Chai ◽  
Hongyuan Guo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electron Microscope ◽  
Dielectric Properties ◽  
Bisphenol A ◽  
Multiwalled Carbon Nanotubes ◽  
High Performance ◽  
Sol Gel ◽  
Alder Reaction ◽  
Multiwalled Carbon ◽  
The Impact

Multiwalled carbon nanotubes (MWCNTs) were modified by oxidizing agent to obtain O-MWCNTs, and the surface of it was coated with active group. 4,4′-Diaminodiphenylmethane bismaleimide (MBMI) was used as matrix, 3,3′-diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE) were used as reactive diluent, polyethersulfone (PES) as toughening agent, and O-MWCNTs as modifier; OMWCNT/PES-MBAE composite was prepared through in situ sol-gel method. The effect of PES and OMWCNTs on the mechanical and dielectric properties of composite was analyzed, and the microstructure was examined by transmission electron microscope (TEM) and scanning electron microscope (SEM). The mechanism of composite toughened by PES and OMWCNTs was observed and analyzed. The results showed that Diels-Alder reaction between MBMI and allyl compounds occurred completely and unsaturated double bond disappeared. O-MWCNTs and PES resin dispersed smoothly in polymer matrix and were used as reinforcement, and PES resin and O-MWCNTs could synergistically improve the properties of the composite and exhibited a typical ductile fracture. The impact and bending strengths were 16.09 kJ/m2 and 153.57 MPa, which were 74.32% and 53.08% higher than those of the MBAE matrix, respectively, and the dielectric constant and the dielectric loss were 3.76 (100 Hz) and 2.79 × 10−3 (100 Hz), when the content of PES was 2 wt% and O-MWCNTs was 0.02 wt%. The outstanding properties of the material made it play an important role in high-performance insulating material applications.

scholarly journals Optical clearing: impact of optical and dielectric properties of clearing solutions on pulmonary tissue mechanics

2017 ◽  
Vol 123 (1) ◽  
pp. 27-37
Author(s):  
David Schwenninger ◽  
Hans-Joachim Priebe ◽  
Matthias Schneider ◽  
Hanna Runck ◽  
Josef Guttmann
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Dielectric Properties ◽  
Lung Tissue ◽  
Tissue Mechanics ◽  
Uniaxial Tensile ◽  
Optical Clearing ◽  
Tissue Biomechanics ◽  
Uniaxial Tensile Testing ◽  
The Impact

Optical clearing allows tissue visualization under preservation of organ integrity. Optical clearing of organs with a physiological change in three-dimensional geometry (such as the lung) would additionally allow visualization of macroscopic and microscopic tissue geometry. A prerequisite, however, is the preservation of the native tissue mechanics of the optically cleared lung tissue. We investigated the impact of optical and dielectric properties of clearing solutions on biomechanics and clearing potency in porcine tissue strips of healthy lungs. After fixation, bleaching, and rehydration, four methods of optical clearing were investigated using eight different protocols. The mechanical and optical properties of the cleared lung tissue strips were investigated by uniaxial tensile testing and by analyzing optical transparency and translucency for red, green, and blue light before, during, and after the biochemical optical clearing process. Fresh tissue strips were used as controls. Best balance between efficient clearing and preserved mechanics was found for clearing with a 1:1 mixture of dimethyl sulfoxide (DMSO) and aniline. Our findings show that 1) the degree of tissue transparency and translucency correlated with the refractive index of the clearing solution index ( r = 0.976, P = 0.0004; and r = 0.91, P = 0.0046, respectively), 2) tissue mechanics were affected by dehydration and the type of clearing solution, and 3) tissue biomechanics and geometry correlated with the dielectric constant of the clearing solution ( r = −0.98, P < 0.00001; and r = 0.69, P = 0.013, respectively). We show that the lower the dielectric constant of the clearing solutions, the larger the effect on tissue stiffness. This suggests that the dielectric constant is an important measure in determining the effect of a clearing solution on lung tissue biomechanics. Optimal tissue transparency requires complete tissue dehydration and a refractive index of 1.55 of the clearing solution. NEW & NOTEWORTHY Investigating optical clearing in porcine lung tissue strips, we found that refractive index and dielectric constant of the clearing solution affected tissue clearing and biomechanics. By documenting the impact of the composition of the clearing solution on clearing potency and preservation of tissue mechanics, our results help to compose optimal clearing solutions. In addition, the results allow conclusions on the molecular interaction of solvents with collagen fibers in tissue, thereby consolidating existing theories about the functionality of collagen.

scholarly journals The Effect of Ca Dopant on the Electrical and Dielectric Properties of BaTi4O9 Sintered Ceramics

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5375
Author(s):  
Asad Ali ◽  
Muhammad Hasnain Jameel ◽  
Sarir Uddin ◽  
Abid Zaman ◽  
Zafar Iqbal ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Energy Storage ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Impedance Spectroscopy ◽  
Energy Loss ◽  
Interfacial Polarization ◽  
Storage Material ◽  
Energy Storage Material ◽  
The Impact

The current research examines the impact of Ca2+ substitution on the phase and electrical properties of (Ba1−xCax)Ti4O9, (x = 0.0, 0.3, 0.6, and 0.9) sintered pellets synthesized by solid-state reaction method. The as-synthesized samples were analyzed using X-ray diffraction (XRD) and impedance spectroscopy. The emergence of orthorhombic phase fit into space group Pnmm was revealed by XRD, and the addition of Ca resulted in a considerable shift in grain size. Dielectric properties were determined using an impedance spectroscopy in a wide frequency range from 1MHz to 3 GHz. The dielectric properties i.e., dielectric constant (εr) and dielectric loss (tanσ), were measured at 3 GHz frequency. The frequency-dependent parameters such as conductivity, dielectric constant, and dielectric loss indicated that the relaxation process is a Maxwell–Wagner type of interfacial polarization. The improved dielectric properties and low energy loss have made (Ba1−xCax)Ti4O9 a prominent energy storage material. This study provides the possibility to improve its dielectric properties and reduce energy loss, making it an excellent energy storage material.

scholarly journals Improvement of the electromechanical properties of thermoplastic polyurethane composite by ionic liquid modified multiwall carbon nanotubes

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 166-178
Author(s):  
Qianwei Xu ◽  
Weijia Zhang
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Ionic Liquid ◽  
Elastic Modulus ◽  
Thermoplastic Polyurethane ◽  
Multiwall Carbon Nanotubes ◽  
Electromechanical Properties ◽  
Polyurethane Composite ◽  
Blending Method ◽  
Multiwall Carbon

Abstract Carbon nanotubes (CNTs) were non-covalently modified by two categories of ionic liquids (ILs), including 1-vinyl-3-ethylimidazole bromide (VEIMBr) and 1-vinyl-3-hexylimidazole bromide (VHIMBr) in the ratio of 1:1 and 1:4, respectively. The surface interaction between CNTs and ILs was well-characterized by FTIR, Raman spectra, XPS, etc. Thermoplastic polyurethane (TPU) containing different amounts of CNTs/ILs was fabricated by melting blending method. TPU-CNTs/ILs composites exhibited simultaneously enhanced electromechanical properties with improved dielectric constant and lowered elastic modulus. The electromechanical sensitivity of sample TPU-3CNT/12VHIMBr increased by approximately 45 times in comparison with that of pure TPU at 200 Hz. Besides, improved dispersion of CNTs/ILs in the TPU matrix was also exhibited.

Effects of thermal maturity and chemical composition of kerogen on its dielectric constant

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. D53-D64
Author(s):  
Archana Jagadisan ◽  
Zoya Heidari
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Thermal Maturity ◽  
Formation Evaluation ◽  
Heat Treated ◽  
Composition And Structure ◽  
Physical And Chemical ◽  
The Impact

Reliable formation evaluation using borehole geophysical measurements in organic-rich mudrocks requires knowledge about the physical properties of kerogen. For instance, estimates of water-filled pore volume are significantly affected by the assumptions made for dielectric permittivity of kerogen, which can be influenced by thermal maturity. However, the impact of thermal maturity of pure kerogen on its dielectric properties is not yet thoroughly understood. We quantify the dielectric constant of kerogen samples extracted from three formations, with different levels of natural thermal maturity, and we identify the impact of thermal maturity on their dielectric properties. We first isolate kerogen from mudrock samples using physical and chemical treatments. We then synthetically mature the samples in a controlled environment and measure their dielectric constant (at 1 GHz) using a microwave resonator. X-ray photoelectron spectroscopy (XPS) monitors the variation in chemical composition of kerogen. The dielectric constant of the kerogen samples varied significantly in the range of 1.89–3.2 upon being heat treated from 25°C to 650°C. The variation in the dielectric constant is explained by the alteration in the chemical composition and structure of kerogen as a result of thermal maturation. XPS measurements also showed an increase in aromatic carbon content in the kerogen samples as the thermal maturity increased. The documented results enable the integration of the kerogen geochemistry to the interpretation of dielectric measurements, which contributes to improved interpretation of dielectric logs in organic-rich mudrocks, and result in enhanced formation evaluation of these reservoirs.

Outstanding dielectric constant and piezoelectric coefficient in electrospun nanofiber mats of PVDF containing silver decorated multiwall carbon nanotubes: assessing through piezoresponse force microscopy

RSC Advances ◽  
2016 ◽  
Vol 6 (8) ◽  
pp. 6251-6258 ◽  
Author(s):  
Maya Sharma ◽  
Vijay Srinivas ◽  
Giridhar Madras ◽  
Suryasarathi Bose
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Piezoelectric Coefficient ◽  
Multiwall Carbon Nanotubes ◽  
Piezoresponse Force Microscopy ◽  
Electrospun Nanofiber ◽  
Force Microscopy ◽  
Nanofiber Mats ◽  
Multiwall Carbon

Alignment of dipoles in one direction leads to high piezoelectric coefficient in PVDF/Ag decorated CNTs.

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