Flexible magnetic copolymer films with high decomposition temperature and stable dielectric properties

2013 ◽  
Vol 25 (1) ◽  
pp. 520-528
Author(s):  
Junji Wei ◽  
Hailong Tang ◽  
Xiaobo Liu
Keyword(s):  
Dielectric Properties ◽  
Decomposition Temperature ◽  
Copolymer Films

scholarly journals Microstructure and Properties of SCE-Al2O3/PES-MBAE Composite

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yufei Chen ◽  
Qiwang Dai ◽  
Xiwang Zhang ◽  
Tao Feng
Keyword(s):  
Dielectric Properties ◽  
Bisphenol A ◽  
Heat Resistance ◽  
Bending Strength ◽  
Sol Gel ◽  
Harmful Effect ◽  
Decomposition Temperature ◽  
Two Phase ◽  
Allyl Compound

SCE-Al2O3was the nano-Al2O3modified by supercritical ethanol and the surface of SCE-Al2O3was 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 SCE-Al2O3as modifier; SCE-Al2O3/PES-MBAE nanocomposite was prepared through in situ sol-gel method. The mechanism of composite toughened by PES was observed and analyzed. FTIR indicated that the reaction between MBMI and allyl compound occurred and SCE-Al2O3had doped into the polymer matrix. SEM showed that PES particle was inlaid in matrix and presented as a two-phase structure in matrix. The heat resistance, dielectric properties, and mechanical properties of SCE-Al2O3/PES-MBAE nanocomposites were evaluated. The results showed that with the incorporation of PES, although the toughness of the material improved, the heat resistance and dielectric properties of material declined, meanwhile. The adulteration of SCE-Al2O3could remedy the harmful effect caused by PES, while the content of SCE-Al2O3was reasonable. The decomposition temperature, dielectric constant, and dielectric loss of composite were 441.23°C, 3.63 (100 Hz), and 1.52 × 10−3(100 Hz); the bending strength and impact strength were 129.22 MPa and 13.19 kJ/mm2, respectively, when the content of SCE-Al2O3was 3 wt% and PES was 5 wt%.

Dielectric properties of lithium-perchlorate-filled acrylonitrile-hexyl methacrylate copolymer films

2015 ◽  
Vol 38 (9) ◽  
pp. 1792-1799
Author(s):  
Meryem Cicek ◽  
Elif Vargun ◽  
Ufuk Abaci ◽  
H. Yuksel Guney
Keyword(s):  
Dielectric Properties ◽  
Lithium Perchlorate ◽  
Copolymer Films ◽  
Hexyl Methacrylate ◽  
Methacrylate Copolymer

scholarly journals Benzoxazine Containing Fluorinated Aromatic Ether Nitrile Linkage: Preparation, Curing Kinetics and Dielectric Properties

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1036 ◽  
Author(s):  
Sijing Chen ◽  
Dengxun Ren ◽  
Bo Li ◽  
Kui Li ◽  
Lin Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Dielectric Properties ◽  
Curing Kinetics ◽  
Decomposition Temperature ◽  
Surface Wettability ◽  
Condensation Polymerization ◽  
Nmr Spectrum ◽  
Kinetics Of ◽  
Bisphenol Af ◽  
Aromatic Ether

Benzoxazine containing fluorinated aromatic ether nitrile linkage (FAEN-Bz) had been synthesized from 2,6-dichlorobenzonitrile, 4,4’-(hexafluoroisopropylidene)diphenol (bisphenol AF), 3-Aminophenol, formaldehyde, phenol by condensation polymerization and Mannich ring-forming reaction. Structures of the monomer were verified by Proton NMR spectrum (1H-NMR) and Fourier transform infrared spectroscopy (FTIR). Curing behaviors and curing kinetics of designed monomers were investigated and discussed. The activation energy was calculated and possible polymerization mechanisms were also proposed. Then, properties of cured polymers including crosslinking degrees, thermal decomposition, surface wettability and energy, and dielectric properties were studied and discussed. Additionally, programmed integral decomposition temperature (IPDT) was also used to evaluate the thermal stability of final polymers. Results indicated that the incorporation of benzoxazine and nitrile resulted in increased thermal stability and char yields. Moreover, the surface wettability and dielectric properties of poly(FAEN-Bz) can be easily controlled by tuning the curing temperatures and time.

Effects of additives on the microstructure and dielectric properties of Ba2Ti9O20 microwave ceramic

2003 ◽  
Vol 18 (5) ◽  
pp. 1179-1187 ◽  
Author(s):  
Sea-Fue Wang ◽  
Yung-Fu Hsu ◽  
Tzuu-Hsing Ueng ◽  
Chung-Chuang Chiang ◽  
Jinn P. Chu ◽  
...  
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Quality Factor ◽  
Sintering Temperature ◽  
Decomposition Temperature ◽  
Nonstoichiometric Compound ◽  
Microwave Ceramic ◽  
Phase Pure ◽  
Excess Amount ◽  
Evolution Phase

Preparation of dense and phase-pure Ba2Ti9O20 is generally difficult to achieve using a solid-state reaction, due to the presence of several thermodynamically stable compounds in the vicinity of the desired composition. This work investigated the effects of various additives (TiO2, MnO, and ZrO2) on the densification, microstructural evolution, phase stability, and dielectric properties of Ba2Ti9O20. Ceramics with theoretical density of ≥95% were achieved in all cases after sintering at 1300 °C. A pure Ba2Ti9O20 phase was obtained by treating the material with TiO2 additions (≤5.6 wt.%) and sintering at temperatures ranging between 1200 and 1350 °C. Ba2Ti9O20 is a nonstoichiometric compound that can accommodate an excess amount of TiO2. As the temperature was increased, pure Ba2Ti9O20 partially decomposed and formed a mixture of BaTi4O9 and Ba2Ti9O20. The ceramic with excess TiO2 sintered at 1390 °C possessed a higher permittivity and a lower quality factor due to the larger grain size and lower density. For ceramic with the addition of ZrO2 (≤6 wt.%), pure Ba2Ti9O20 phase was obtained after sintering between 1200 and 1390 °C, and the quality factor was improved. The decomposition temperature of the Ba2Ti9O20 phase was greater than 1390 °C. For sintering temperatures ≥1350 °C, the extent of Ba2Ti9O20 phase decreased with MnO additions. As the MnO content reached 0.5 wt.%, only BaTi4O9 and TiO2 phases existed, suggesting a decrease in the decomposition temperature of Ba2Ti9O20 with the addition of MnO. The microwave properties of the ceramics degraded significantly at the sintering temperature of 1390 °C.

Sintering behavior and dielectric properties of pyrochlore Pb2FeWO6.5

1994 ◽  
Vol 9 (2) ◽  
pp. 266-269 ◽  
Author(s):  
Chung-Hsin Lu ◽  
Nobuyasu Mizutani
Keyword(s):  
Dielectric Properties ◽  
Grain Growth ◽  
Hot Isostatic Pressing ◽  
Applied Pressure ◽  
Decomposition Temperature ◽  
Dielectric Constants ◽  
Sintering Behavior ◽  
Low Dielectric ◽  
Low Dissipation ◽  
Pyrochlore Type

Pyrochlore-type Pb2FeWO6.5 is difficult to be sintered without applied pressure at temperatures lower than its decomposition temperature. Through hot pressing or hot isostatic pressing processes, densification of specimens is greatly enhanced; moreover, grain growth during sintering is effectively suppressed. Densified Pb2FeWO6.5 exhibits paraelectric characteristic from −135°to −2 °C with low dielectric constants and low dissipation factors. The dielectric constants show rather weak dependence of temperature and frequency.

scholarly journals Synthesis and characterization of polyurethane–polysiloxane block copolymers modified by α,ω-hydroxyalkyl polysiloxanes with methacrylate side chain

2021 ◽  
Vol 28 (1) ◽  
pp. 528-539
Author(s):  
Su Xiaofeng ◽  
Yu Yitao ◽  
Li Bing ◽  
Wang Jing ◽  
Lu Chuan ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Soft Segment ◽  
Waterborne Polyurethane ◽  
Thermomechanical Analysis ◽  
Decomposition Temperature ◽  
Side Chain ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Copolymer Films

Abstract In order to prepare polyurethane–polysiloxane block copolymers, α,ω-hydroxyalkyl polysiloxanes with methacrylate side chain and α,ω-bis(2-methyl-3-hydroxypropyl)polymethyl(2-methyl-methylpropanoate) siloxanes, were synthesized and characterized in this study. The syntheses process included hydroxyl protection, hydrosilylation, deprotection, and ring-opening equilibrium reactions. The intermediates and target products were characterized by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance methods. The characterization results showed that each step was successfully carried out in all the cases. Then the waterborne polyurethane–polysiloxane block copolymers were prepared via step-growth polymerization. The properties of the block copolymer films were characterized by thermal gravimetric analysis, differential scanning calorimetry, and dynamic thermomechanical analysis methods in detail. The experimental results showed that the block introduction of hydroxyalkyl polysiloxane could reduce the water absorption of waterborne polyurethane from 62 to 11%, and significantly improve the water resistance of polyurethane. With the introduction of polysiloxane, the tensile strength decreased and the elongation at break increased. At the same time, with the increase of the polysiloxane content, the glass transition temperature of the soft segment decreased to −56.4°C and the thermal decomposition temperature increased to 300°C. The results revealed that the introduction of polysiloxane could effectively improve the comprehensive performance of polyurethane–polysiloxane block copolymer films.

Anomalies of dielectric properties of vinylidene fluoride-trifluoroethylene copolymer films

2008 ◽  
Vol 50 (3) ◽  
pp. 562-567 ◽  
Author(s):  
A. V. Solnyshkin ◽  
M. Wegener ◽  
W. Künstler ◽  
R. Gerhard-Multhaupt
Keyword(s):  
Dielectric Properties ◽  
Vinylidene Fluoride ◽  
Copolymer Films
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