Effects of interface bonding on the corona resistance of the polyimide/nano-Al2O3 three-layer composite films

2017 ◽  
Vol 30 (10) ◽  
pp. 1240-1246 ◽  
Author(s):  
Xinyu Ma ◽  
Lizhu Liu ◽  
Hongju He ◽  
Ling Weng
Keyword(s):  
Composite Film ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Electrical Breakdown ◽  
Layer Structure ◽  
Composite Films ◽  
Raw Material ◽  
Breakdown Field ◽  
Layer Composite ◽  
Corona Resistance

Polyimides (PIs) are widely used in many fields including aerospace and microelectronics. Due to their poor corona resistance, their practical applications were limited, especially in the field of variable frequency motors. In this study, we have achieved for the first time to increase the corona resistance by controlling the preparation process of the three-layered PI composite. A series of PI/nano-Al2O3 composite films with novel three-layer structure were prepared by in situ polymerization employing pyromellitic dianhydride and 4,4-diaminodiphenyl as raw material, N, N-dimethylacetamide as solvent, and doping of nano-Al2O3. The first layer of the PI/Al2O3 composite film was characterized by Fourier transform infrared spectroscopy, and the imidization rate under different processes was calculated. The interface structures and bonding conditions of the composite films were characterized by scanning electron microscope, and the surface morphologies of the composite films treated by different corona-resistance times were investigated. X-ray diffraction analysis was also used to study the effect of nano-Al2O3 on PIs with different imidization ratios. The corona-resistance time and breakdown field strength of the composite films prepared by different processes were also tested. The results indicated that the combination of the three-layer composite film and the corona-resistance abilities of the composite membrane surface was enhanced by increasing the imidization rate. Meanwhile, the corona-resistance time and the electrical breakdown strength of composite films were also improved by increasing the imidization rate.

Effect of imidization process on the performance of PI/nano-Al2O3 three layer composite film

2017 ◽  
Vol 46 (4) ◽  
pp. 327-331 ◽  
Author(s):  
Lizhu Liu ◽  
Hongju He ◽  
Ling Weng ◽  
Xiaorui Zhang
Keyword(s):  
Composite Film ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Composite Films ◽  
Inorganic Materials ◽  
Raw Material ◽  
Nanocomposite Films ◽  
Breakdown Field ◽  
Content Type ◽  
The Impact

Purpose The purpose of this paper was to comprehensively understand the effects of imidization process on the structure and properties of polyimide (PI) films through the preparation and characterization of a variety of PI/aluminium oxide (Al2O3) nanocomposite films by using several imidization-based strategies. Design/methodology/approach Poly(amic acid) (PAA) containing different amounts of inorganic materials (namely, 0 Wt.%, 4 Wt.%, 8 Wt.%, 12 Wt.% and 16 Wt.%) was synthesized by using pyromellitic dianhydride and 4,4-diaminodiphenyl ether as raw material and N,N-dimethylacetamide as solvent. Subsequently, the solution obtained was casted on a glass substrate and dried by the means of various curing processes. The micro-structure, Fourier transform–infrared spectral features, breakdown field strength, dielectric properties and the corona-resistant time parameters of films were achieved. Findings The imidization process influences substantially the properties of composite films. Therefore, as the imidization rate is increased, the corona-resistant time and the electrical breakdown strength of composite films are also improved, while the dielectric constant faces a+ decreasing. Research limitations/implications In this paper, the impact of imidization process on the performance of PI/nano-Al2O3 three-layered composite film is reported. However, there are multiple factors governing these systems (such as, interlayer thickness ratio and humidity), which are not discussed herein. Originality/value The current study expounds the relationship between imidization ratios as well as the effect of imidization ratio on the performance of the film.

The Effects of Coupling Agents on the Electrical Properties of Polyimide/TiO2 Hybrid Films

2014 ◽  
Vol 556-562 ◽  
pp. 371-374
Author(s):  
Kai Yan ◽  
Xiao Xu Liu
Keyword(s):  
Composite Film ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Composite Films ◽  
Electric Breakdown ◽  
Future Application ◽  
Breakdown Field ◽  
Coupling Agents ◽  
Hybrid Films ◽  
Simple Method

Polyamides (PI)-matrix composite films with inorganic nanoTiO2 have been fabricated by employing in situ polymerization. Before addition, TiO2 particles were firstly modified with coupling agents (KH550). The electric breakdown strength and micromorphology of hybrid films were characterized and investigated. Results indicated that nanoTiO2 particles were homogeneously dispersed in the PI matrix for the addition of coupling agents and the electric breakdown strength of PI/TiO2 composite films with KH550 were better than unmodified PI composite film. The breakdown field strength and tensile modulus of PI composite film with the inorganic content of 5 wt% were 200.1 (KV/mm). So the using coupling agent can effectively improve the compatibility and the homogenous dispersion of nanoTiO2 particles in PI matrix. Meanwhile, the procedure described here offers an effective and simple method to produce PI/TiO2 with excellent electrical needed for future application in electrical engineering field.

Fabrication, Morphology and Properties of Polyimide/Al2O3 Nanocomposite Films via Surface Modification and Ion-Exchange Technique

2018 ◽  
Vol 921 ◽  
pp. 91-98
Author(s):  
Ming Yu Zhang ◽  
Li Zhu Liu ◽  
K.S. Hui
Keyword(s):  
Ion Exchange ◽  
Composite Film ◽  
Original Film ◽  
Treatment Time ◽  
Breakdown Strength ◽  
Composite Films ◽  
Nanocomposite Films ◽  
Polyimide Films ◽  
Force Microscopy ◽  
Corona Resistance

Polyimide films with Al2O3composite layers were prepared by KOH solution surface hydrolysis, ion exchange and heat treatment. Scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray diffractometry (XRD), thermo gravimetric analyzer (TGA), breakdown voltage tester, high frequency pulse voltage machine were performed to characterize the micromorphology, thermal stability, mechanical properties, electric breakdown strength, and corona resistance time of composite films. Results indicated that the thermal properties of the composite film are better than the original film. The corona resistance time of the composite film was longer than that of the pristine film. The composite film had the longest corona resistance time and reached 101.2min while the KOH treatment time was 90min.

Effect of Hydrophilic and Hydrophobic SiO2 Particles on Performances of PI/Al2O3 Composite Films

2015 ◽  
Vol 645-646 ◽  
pp. 26-31 ◽  
Author(s):  
Yuan Yuan Li ◽  
Li Zhu Liu ◽  
Hui Shi ◽  
Ling Weng ◽  
Wie Wei Cui
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Field Strength ◽  
In Situ Polymerization ◽  
Composite Films ◽  
Breakdown Field ◽  
Inorganic Particles ◽  
Transmission Electron ◽  
Breakdown Field Strength ◽  
Corona Resistance

In this paper, we mainly analyzed the different influence of hydrophilic SiO2 particles and hydrophobic SiO2 particles on the properties of PI/Al2O3 films. PI/Al2O3/SiO2(hydrophilic) films and PI/Al2O3/SiO2(hydrophobic) films with 16 wt% content of Al2O3 and 3 wt‰, 5 wt‰, 7 wt‰ content of SiO2 respectively were prepared by in-situ polymerization method. Firstly, the hydrophilic SiO2 particles and hydrophobic SiO2 particles were investigated by transmission electron microscopy (TEM), infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed that the average sizes and infrared characteristic peaks of two kinds of SiO2 particles were similar, and two kinds of SiO2 particles were amorphous inorganic particles. Then the morphology of the composite films was characterized by scanning electron microscopy (SEM), and the mechanical properties, the breakdown field strength and corona resistant time were tested and analyzed. Results indicated that inorganic particles added to PI/Al2O3/SiO2(hydrophilic) films dispersed better than that of PI/Al2O3/SiO2(hydrophobic) films. When the content of SiO2 particles was 5 wt‰, the mechanical properties and corona resistance of PI/Al2O3/SiO2(hydrophilic) films were best, the tensile strength, elongation at break and corona resistance times of the films were: 132.44 MPa, 12.64%, 378 min, respectively. The breakdown field strength of PI/Al2O3/SiO2(hydrophilic) films was only 211.15 kV/mm, and inferior to that of PI/Al2O3/SiO2(hydrophobic) films (232.08 kV/mm).

Preparation and Dielectric Property of Al2O3 Surface Coating Modified BaTiO3/Polyimide Composite Film

2014 ◽  
Vol 908 ◽  
pp. 63-66
Author(s):  
Ya Jun Wang ◽  
Xiao Juan Wu ◽  
Chang Gen Feng
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Composite Film ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Chemical Properties ◽  
Dielectric Strength ◽  
Xrd Analysis ◽  
Nanocomposite Films ◽  
The Matrix

Polyimide (PI) was chosen as the matrix of the composite, barium titanate/polyimide (BT/PI) nanocomposite films were prepared by in situ polymerization. In order to improve the dispersion and the physical-chemical properties of BT surface, barium titanate was modified by Al2O3coating and modified BT/PI nanocomposite films were prepared. The prepared modified BT was characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of the composites were characterized in detail. It was shown that surface modification with Al2O3is the chemical process and there were new substances forming. When BT was modified by 10 wt% Al2O3, the dielectric constant of the composite film was 18.96 (103Hz), the loss tangent 0.005, breakdown strength 70 MV·m-1, energy storage density 0.41 J·cm-3. The dielectric constant of BT modified by Al2O3is decreased while the dielectric strength of the modified BT/PI composite film is increased.

Dielectric behavior of a flexible three-phase polyimide/BaTiO3/multi-walled carbon nanotube composite film

2016 ◽  
Vol 09 (01) ◽  
pp. 1650006 ◽  
Author(s):  
Junli Wang ◽  
Shengli Qi ◽  
Yiyi Sun ◽  
Guofeng Tian ◽  
Dezhen Wu
Keyword(s):  
Composite Film ◽  
Volume Fraction ◽  
In Situ Polymerization ◽  
Composite Films ◽  
Dielectric Behavior ◽  
Low Dielectric ◽  
Three Phase ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
High Dielectric

A three-phase composite film was produced by inserting multi-walled carbon nanotubes (MWCNTs) and BaTiO3 nanoparticles into polyimide (PI). The combination of in-situ polymerization and water-based preparation involved in the experiment ensured fillers’ homogeneous dispersion in the matrix, which led to flexible shape of the composite films. The dielectric properties of composite films as a function of the frequency and the volume fraction of MWCNTs were studied. Such composite film displayed a high dielectric constant (314.07), low dielectric loss and excellent flexibility at 100[Formula: see text]Hz in the neighborhood of percolation threshold (9.02 vol%) owing to the special microcapacitor structure. The experimental results were highly consistent with the power law of percolation theory.

Fabrication of an all-polysaccharide composite film from hemicellulose and methylcellulose

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 6716-6726
Author(s):  
Gui-Chun Hu ◽  
Shiyu Fu ◽  
Fuqiang Chu ◽  
Guangyuan Wu
Keyword(s):  
Aqueous Solutions ◽  
Composite Film ◽  
Surface Charge ◽  
Layer Structure ◽  
Composite Films ◽  
Packaging Material ◽  
Packaging Film ◽  
Compact Layer ◽  
Significant Interest ◽  
Potential Applications

There is significant interest in preparing packaging film from sustainable polysaccharides, especially hemicellulose (HC). Hemicellulose isolated from wheat straw tends to aggregate into dissolved particles in aqueous solutions and to form poor films. When methylcellulose (MC) was added into the HC solution, HC and MC formed a HC-MC complex. With increased MC content, the size of the HC-MC complex decreased, and its surface charge increased at the same time. When 35 wt% MC was added into the HC, a continuous HC-MC film formed in the layer structure. The HC-MC film with 75 wt% MC showed a more compact layer structure compared with other films. The tensile strengths of the HC-MC film increased with the MC addition. When MC was added to 75 wt%, the tensile strengths of the HC-MC film reached their maximum values, which were higher than that of MC film. This high film strength suggested these HC-MC composite films have potential applications in packaging material.

Characteristics of Nanocomposite ZrO2/Al2O3 Films Deposited by Plasma-Enhanced Atomic Layer Deposition

2007 ◽  
Vol 7 (11) ◽  
pp. 4180-4184
Author(s):  
Sun Jin Yun ◽  
Jung Wook Lim ◽  
Hyun-Tak Kim
Keyword(s):  
Atomic Layer Deposition ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Composite Films ◽  
Atomic Layer ◽  
Nano Composite ◽  
Layer Deposition ◽  
Electrical Breakdown Strength ◽  
Film Characteristics ◽  
Al2o3 Films

Nanocomposite ZrO2/Al2O3 (ZAO) films were deposited on Si by plasma-enhanced atomic layer deposition and the film characteristics including interfacial oxide formation, dielectric constant (k), and electrical breakdown strength were investigated without post-annealing process. In both the mixed and nano-laminated ZAO films, the thickness of the interfacial oxide layer (TIL) was considerably reduced compared to ZrO2 and Al2O3 films. The TIL was 0.8 nm in nano-composite films prepared at a mixing ratio (ZrO2:Al2O3) of 1:1. The breakdown strength and the leakage current level were greatly improved by adding Al2O3 as little as 7.9% compared to that of ZrO2 and were enhanced more with increasing content of Al2O3. The k of ZrO2 and mixed ZAO (Al2O3 7.9%) films were 20.0 and 16.5, respectively. These results indicate that the addition of Al2O3 to ZrO2 greatly improves the electrical properties with less cost of k compared to the addition of SiO2.

scholarly journals Carrier Transport and Molecular Displacement Modulated dc Electrical Breakdown of Polypropylene Nanocomposites

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1207 ◽  
Author(s):  
Daomin Min ◽  
Chenyu Yan ◽  
Rui Mi ◽  
Chao Ma ◽  
Yin Huang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Charge Transport ◽  
Carrier Mobility ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Dielectric Materials ◽  
Breakdown Field ◽  
Smart Power ◽  
Electrical Breakdown Strength ◽  
Effective Carrier

Dielectric energy storage capacitors have advantages such as ultra-high power density, extremely fast charge and discharge speed, long service lifespan and are significant for pulsed power system, smart power grid, and power electronics. Polypropylene (PP) is one of the most widely used dielectric materials for dielectric energy storage capacitors. It is of interest to investigate how to improve its electrical breakdown strength by nanodoping and the influencing mechanism of nanodoping on the electrical breakdown properties of polymer nanocomposites. PP/Al2O3 nanocomposite dielectric materials with various weight fraction of nanoparticles are fabricated by melt-blending and hot-pressing methods. Thermally stimulated current, surface potential decay, and dc electrical breakdown experiments show that deep trap properties and associated molecular chain motion are changed by incorporating nanofillers into polymer matrix, resulting in the variations in conductivity and dc electrical breakdown field of nanocomposite dielectrics. Then, a charge transport and molecular displacement modulated electrical breakdown model is utilized to simulate the dc electrical breakdown behavior. It is found that isolated interfacial regions formed in nanocomposite dielectrics at relatively low loadings reduce the effective carrier mobility and strengthen the interaction between molecular chains, hindering the transport of charges and the displacement of molecular chains with occupied deep traps. Accordingly, the electrical breakdown strength is enhanced at relatively low loadings. Interfacial regions may overlap in nanocomposite dielectrics at relatively high loadings so that the effective carrier mobility decreases and the interaction between molecular chains may be weakened. Consequently, the molecular motion is accelerated by electric force, leading to the decrease in electrical breakdown strength. The experiments and simulations reveals that the influence of nanodoping on dc electrical breakdown properties may origin from the changes in the charge transport and molecular displacement characteristics caused by interfacial regions in nanocomposite dielectrics.

A Robust Multilayer Dielectric Elastomer Actuator

2015 ◽  
Vol 1718 ◽  
pp. 145-155
Author(s):  
Mason A. Wolak ◽  
Lei Zhu
Keyword(s):  
Vinylidene Fluoride ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Layer Structure ◽  
Axial Strain ◽  
Dielectric Strength ◽  
Dielectric Elastomer ◽  
Effective Field ◽  
Electromechanical Performance ◽  
Multilayer Dielectric

ABSTRACTWe recently fabricated and characterized a new class of multilayer dielectric elastomer films comprising alternating layers of two different polymers, at least one of which is an elastomer. The films discussed here contain THV (a terpolymer of poly(vinylidene fluoride)) and poly(ethylene octene) [EO] elastomer. The multilayer structure provides improved dielectric and electromechanical performance relative to monolithic films of THV or EO. These properties are controlled by the composition and the layer structure. For example, increasing the concentration of the elastomeric EO component increases the maximum axial strain (sz). Layering EO with THV also increases the breakdown strength (EB ∼ 265 - 300 V/µm) relative to monolithic EO (EB ∼ 150 V/µm) or THV (EB ∼ 245 V/µm) control films. This enhancement in breakdown strength is consistent with a barrier effect that is also observed in multilayer polymer capacitor films. The increase in breakdown strength allows 512-layer 75 vol% EO / 25 vol% THV films to achieve maximum axial strains of sz nearly 4%, higher than can be attained by either EO or THV films alone. In addition, layering reduces remnant strain and electromechanical hysteresis by limiting the effective field within the THV layers. The 75% EO/ 25% THV films show robust operational longevity with little loss in axial strain when subjected to repeated actuation at Emax = 225 V/µm (producing sz = 2.2%). Under these conditions, we observe 3,000 consecutive actuation cycles with no electrical breakdown. In comparison, single component EO control films undergo electrical breakdown at this field and THV control films survive only a few hundred actuation cycles under these conditions. The results demonstrate that multilayering is an effective technique to increase the dielectric strength of elastomer materials and in turn improve upon strain and operational longevity (repeated actuation cycles) characteristics.

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