Analysis on the Mechanical and Electrical Properties of PI/MWNTs Nano-Hybrid Films

2011 ◽  
Vol 675-677 ◽  
pp. 1241-1244
Author(s):  
Ming Yan Zhang ◽  
Peng He Diao ◽  
Xiao Ying Zhu
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
In Situ Polymerization ◽  
Low Frequency ◽  
Frequency Region ◽  
Hybrid Films ◽  
Polyimide Films ◽  
High Frequency Region ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this paper, MWNTs (multi-walled carbon nanotubes) were modified by the mixture acid of H2SO4 and HNO3, the PI (polyimide)/MWNTs nano-hybrid films were prepared by means of ultrasonic vibration and in-situ polymerization. The surface morphology was characterized by SEM, the chemical structure was characterized by FT-IR. The tensile strength and Young’s modulus increased at first and then decreased with the increase of MWNTs content. The dielectric constant was tested at a frequency of 1 kHz. The dielectric constant had no obvious variation when MWNTs content was less than 2.9 wt%, as the MWNTs content exceeded 5.36 wt%, the dielectric constant increased rapidly. In general, the dielectric loss of PI/MWNTs nano-hybrid films was higher than the dielectric loss of pure polyimide films. The dielectric loss increased slowly in low frequency region but rapidly in high frequency region. All the test results were attributed to the dispersion degree of MWNTs doping and the combination degree between PI matrix and modified MWNTs in PI/MWNTs nano-hybrid films.

Preparation and Electrical Properties of the Polyimide/Multi-Walled Carbon Nanotubes (MWNTs) Nanocomposites

2011 ◽  
Vol 675-677 ◽  
pp. 1237-1240 ◽  
Author(s):  
Ming Yan Zhang ◽  
Xiao Ying Zhu ◽  
Peng He Diao ◽  
Wen Jia Wang ◽  
Xiao Dong Li
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Dielectric Loss ◽  
Loss Factor ◽  
In Situ Polymerization ◽  
Dielectric Loss Factor ◽  
Nanocomposite Films ◽  
Sharp Drop ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The polyimide/multi-walled carbon nanotubes (MWNTs) nanocomposite films were prepared by means of ultrasonic blending and in-situ polymerization. MWNTs were modified with mixed strong acid in order to improve the chemical compatibility between polyimide matrix and MWNTs. The effects of the incorporation of MWNTs on the electrical property were researched in this study. The results showed that with the increase of the content of acid-modified MWNTs, the dielectric strength decreased gradually and had a sharp drop when the addition content was close to 0.6 wt%, the dielectric constant and the dielectric loss factor increased obviously. With the rise of the test frequency, the dielectric constant declined slowly and the dielectric loss factor increased. The corona resistance time of the nanocomposite films was all higher than that of the pure polyimide.

scholarly journals An insight on spectral, microstructural, electrical and mechanical characterization of ammonium oxalate monohydrate crystals

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Stella Mary ◽  
S. Shahil Kirupavathy
Keyword(s):  
Thermal Stability ◽  
Dielectric Constant ◽  
Grown Crystal ◽  
Ammonium Oxalate ◽  
Low Frequency ◽  
Frequency Region ◽  
Etch Pits ◽  
High Frequency Region ◽  
Good Thermal Stability ◽  
Cell Parameters

AbstractSingle crystals of ammonium oxalate monohydrate (AO) were grown using the slow evaporation solution growth technique. The cell parameters obtained from the single crystal diffraction experiments matched with those known earlier showed that the grown crystals were composed of AO. The variation of dielectric constant as a function of frequency shows that the dielectric constant is relatively high in low frequency region and low in the high frequency region. Microhardness study indicates that the grown AO crystal is of a soft nature. The TG and DTA studies reveal that the grown crystal has good thermal stability and can be exploited in various applications up to 100 °C. There is a change in morphology of etch pits on prolonged etching. A very low value of dielectric constant supports that the material can be exploited in photonic and electro-optic devices. Thermal stability of the grown crystal is good.

scholarly journals Dielectric Spectroscopy of Grape Juice at Microwave Frequencies

2015 ◽  
Vol 29 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Ravika Vijay ◽  
Ritu Jain ◽  
Krishna S. Sharma
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
High Frequency ◽  
Loss Factor ◽  
Low Frequency ◽  
Grape Juice ◽  
Angular Frequency ◽  
Dielectric Loss Factor ◽  
High Frequency Region ◽  
Different Temperatures

Abstract The complex permittivity of fresh juice of two cultivars of grapes, Sultania (green grapes) and Black Monukka (black grapes) was measured in terms of the dielectric constant and dielectric loss factor over the frequency range from 1 to 50 GHz and at temperatures ranging from 30 to 60°C, by using the PNA network analyzer model E8364C and open ended coaxial probe 85070E. The Cole-Cole plots and dielectric constant vs. (angular frequency) dielectric loss factor and dielectric constant vs. dielectric loss factor/(angular frequency) regression lines at different temperatures were used in Debye approximation to predict relaxation frequency of molecules for the two cultivars of grapes in the low frequency and high frequency limits, respectively. It was observed that the acidic character of green grapes is responsible for the large amplitude vibrational peaks in dielectric loss factor - frequency curves, in the high frequency region at higher temperatures. On the other hand, excess of sugar in black grapes suppresses the activity of water molecules, thereby suppressing the vibrational peaks at higher frequencies. Different relaxation frequencies found for the two cultivars of grapes suggest that they have different molecular structure.

Dielectric Properties of Sol-Gel Prepared Ni-Doped CaCu3Ti4O12 Ceramics

2012 ◽  
Vol 204-208 ◽  
pp. 4193-4196
Author(s):  
Lei Jiao ◽  
Hui Li ◽  
Yan Wei Yang ◽  
Tian Ping Wang
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sol Gel ◽  
Low Frequency ◽  
Frequency Region ◽  
Dielectric Constants ◽  
High Frequency Region ◽  
Xrd Pattern ◽  
Calcium Copper Titanate ◽  
Titanate Ceramics

Dielectric properties of sol–gel prepared Ni-doped calcium copper titanate Ceramics (CCNTO) are investigated. For the x of CaCu3NixTi4O12+x is 0, 0.1, 0.2, 0.3 respectively. The XRD pattern shows that crystal structure of the sample without Ni is basically single-phase. The dielectric properties of CCNTO were analyzed by Agilent 4294A. The experimental results show that the sample has a better dielectric properties when x=0.2. The maximum dielectric constants is found when x=0.2. The dielectric loss decreased with the increases of Ni in the low frequency region, the high frequency region is just the opposite, the sample has lower dielectric loss in the low frequency region when x=0.2.

scholarly journals Frequency Dependent Electrical Properties of Ferroelectric Ba0.8Sr0.2TiO3 Thin Film

1970 ◽  
Vol 17 (2) ◽  
pp. 186-190 ◽  
Author(s):  
Ala’eddin A. SAIF ◽  
Zul Azhar ZAHID JAMAL ◽  
Zaliman SAULI ◽  
Prabakaran POOPALAN
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
High Frequency ◽  
Room Temperature ◽  
Electric Modulus ◽  
Low Frequency ◽  
Frequency Region ◽  
Electrical Parameters ◽  
High Frequency Region ◽  
Frequency Dependent

The frequency dependent electrical parameters, such as impedance, electric modulus, dielectric constant and AC conductivity for ferroelectric Ba0.8Sr0.2TiO3 thin film have been investigated within the range of 1 Hz and 106 Hz at room temperature. Z* plane shows two regions corresponding to the bulk mechanism and the distribution of the grain boundaries-electrodes process. M" versus frequency plot reveals a relaxation peak, which is not observed in the ε″ plot and it has been found that this peak is a non-Debye-type. The frequency dependent conductivity plot shows three regions of conduction processes, i. e., a low-frequency region due to DC conduction, a mid-frequency region due to translational hopping motions and a high-frequency region due to localized hopping and/or reorientational motion.http://dx.doi.org/10.5755/j01.ms.17.2.490

Enhanced dielectric properties and thermostability in polyimide composites with core-shell structured polyimide@BaTiO3 nanoparticles

2021 ◽  
pp. 095400832199352
Author(s):  
Wei Deng ◽  
Guanguan Ren ◽  
Wenqi Wang ◽  
Weiwei Cui ◽  
Wenjun Luo
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Energy Density ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Dielectric Materials ◽  
High Energy ◽  
Amic Acid ◽  
High Energy Density ◽  
Core Shell

Polymer composites with high dielectric constant and thermal stability have shown great potential applications in the fields relating to the energy storage. Herein, core-shell structured polyimide@BaTiO3 (PI@BT) nanoparticles were fabricated via in-situ polymerization of poly(amic acid) (PAA) and the following thermal imidization, then utilized as fillers to prepare PI composites. Increased dielectric constant with suppressed dielectric loss, and enhanced energy density as well as heat resistance were simultaneously realized due to the presence of PI shell between BT nanoparticles and PI matrix. The dielectric constant of PI@BT/PI composites with 55 wt% fillers increased to 15.0 at 100 Hz, while the dielectric loss kept at low value of 0.0034, companied by a high energy density of 1.32 J·cm−3, which was 2.09 times higher than the pristine PI. Moreover, the temperature at 10 wt% weight loss reached 619°C, demonstrating the excellent thermostability of PI@BT/PI composites. In addition, PI@BT/PI composites exhibited improved breakdown strength and toughness as compared with the BT/PI composites due to the well dispersion of PI@BT nanofillers and the improved interfacial interactions between nanofillers and polymer matrix. These results provide useful information for the structural design of high-temperature dielectric materials.

Anderson-Stuart Model to Analyze AC and DC Conductivity of Lithium Zinc-Silicate Glass / Glass-Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 919-924
Author(s):  
M.S. Jogad ◽  
V.K. Shrikhande ◽  
A.H. Dyama ◽  
L.A. Udachan ◽  
Govind P. Kothiyal
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Low Frequency ◽  
Frequency Region ◽  
Dc Conductivity ◽  
Frequency Range ◽  
High Frequency Region ◽  
Dc Conductivities ◽  
Conductivity Variation ◽  
Different Temperatures

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity. The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.

Analysis of the Characteristics on Dielectric Barrier Discharges Depending on the Relative Permittivity and Frequency

2018 ◽  
Vol 875 ◽  
pp. 113-116 ◽  
Author(s):  
Don Kyu Lee
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Relative Permittivity ◽  
Discharge Voltage ◽  
Frequency Region ◽  
Dielectric Barrier Discharges ◽  
Dielectric Barrier ◽  
Dielectric Layers ◽  
Green Sheet ◽  
Barrier Discharges

Various studies are being conducted on the application of DBD (Dielectric barrier discharges). The internal dielectric has a very important characteristic on DBD, thus we analyze of the characteristics on dielectric barrier discharges depending on the relative permittivity and frequency. Through simulation, the discharge voltage was calculated based on relative permittivity and frequency of real used dielectrics (Green sheet, Down dielectric, white dielectric). We investigate that increased relative permittivity and fast frequency occur the decrease of the firing voltage. Also, we investigate the frequency dependence of the dielectric constant and dielectric loss of dielectric layers measured at a frequency region of 100Hz to 10MHz. In a condition of drive within 1MHz, with regard to the change of real and imaginary part according to frequency, it has quite stable dielectric constant in the condition of drive within 1MHz.

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