Fabrication and characterization of polyimide/Al2O3 composite films via surface modification and ion exchange technique

2016 ◽  
Vol 45 (1) ◽  
pp. 30-37 ◽  
Author(s):  
M.Y. Zhang ◽  
L.Z. Liu ◽  
L. Weng ◽  
W.W. Cui ◽  
K.S. Hui
Keyword(s):  
Surface Modification ◽  
Ion Exchange ◽  
Breakdown Strength ◽  
Composite Films ◽  
Annealing Treatment ◽  
Ambient Air ◽  
Ammonia Solution ◽  
Excellent Thermal Stability ◽  
Content Type ◽  
General Importance

Purpose – The aim of this study was to fabricate polyimide (PI)/Al2O3 composite films via surface modification and ion exchange techniques, and examine their properties. Design/methodology/approach – The method involves hydrolyzing the PI film double surface layers in an aqueous potassium hydroxide (KOH) solution and incorporating aluminium ions (Al3+) into the hydrolyzed layers of the PI film via subsequent ion exchange, followed by a treatment of the Al3+-loaded PI films with an aqueous ammonia solution, which leads to the formation of Al(OH)3 in the surface-modified layers. After a final thermal annealing treatment in ambient air, the Al(OH)3 decomposes to Al2O3, and forms composite layers on both surfaces of the re-imidized PI film. Findings – The PI/Al2O3 composite film obtained with a 6 hours of KOH treatment exhibited excellent thermal stability, good mechanical properties and better electric breakdown strength and corona-resistance properties than the pristine PI film. Practical implications – The method for obtaining the composite films in this paper is worth consideration, but additional research will be needed. Furthermore, this method is of general importance for the fabrication of composite PI films with tailored properties. Originality/value – This study showed that surface modification and ion-exchange techniques are powerful methodologies for the fabrication of PI/Al2O3 composite films.

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 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.

scholarly journals Bioinspired Dielectric Film with Superior Mechanical Properties and Ultrahigh Electric Breakdown Strength Made from Aramid Nanofibers and Alumina Nanoplates

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3093
Author(s):  
Qiu-Wanyu Qing ◽  
Cheng-Mei Wei ◽  
Qi-Han Li ◽  
Rui Liu ◽  
Zong-Xi Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bonding ◽  
Composite Film ◽  
Breakdown Strength ◽  
Composite Films ◽  
Electrical Equipment ◽  
Electric Breakdown ◽  
Excellent Thermal Stability ◽  
Practical Applications ◽  
Al2o3 Composite

Materials with excellent thermal stability, mechanical, and insulating properties are highly desirable for electrical equipment with high voltage and high power. However, simultaneously integrating these performance portfolios into a single material remains a great challenge. Here, we describe a new strategy to prepare composite film by combining one-dimensional (1D) rigid aramid nanofiber (ANF) with 2D alumina (Al2O3) nanoplates using the carboxylated chitosan acting as hydrogen bonding donors as well as soft interlocking agent. A biomimetic nacreous ‘brick-and-mortar’ structure with a 3D hydrogen bonding network is constructed in the obtained ANF/chitosan/Al2O3 composite films, which provides the composite films with exceptional mechanical and dielectric properties. The ANF/chitosan/Al2O3 composite film exhibits an ultrahigh electric breakdown strength of 320.1 kV/mm at 15 wt % Al2O3 loading, which is 50.6% higher than that of the neat ANF film. Meanwhile, a large elongation at break of 17.22% is achieved for the composite film, integrated with high tensile strength (~233 MPa), low dielectric loss (<0.02), and remarkable thermal stability. These findings shed new light on the fabrication of multifunctional insulating materials and broaden their practical applications in the field of advanced electrics and electrical devices.

Study on friction behavior of SiC-B4C composite ceramics after annealing

2019 ◽  
Vol 72 (5) ◽  
pp. 673-679 ◽  
Author(s):  
Wei Zhang ◽  
Seiji Yamashita ◽  
Takeshi Kumazawa ◽  
Fumihito Ozeki ◽  
Hideki Hyuga ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Annealing Treatment ◽  
Ambient Air ◽  
Composite Ceramics ◽  
Low Friction ◽  
Friction Behavior ◽  
Friction Coefficients ◽  
Content Type ◽  
Lubricating Layer ◽  
Surface Profiles

Purpose This study aims to investigate the friction behavior of SiC-B4C composite ceramics treated by annealing in air sliding against SiC balls. Design/methodology/approach The dry sliding tests were performed with a ball-on-disk tribometer in ambient air condition. Analysis of friction coefficient, phase compositions of the surfaces, morphologies of worn surfaces of disks and wear scars of balls and surface profiles of wear tracks for disks were carried out using Raman spectroscope, microscope and surface profilometer. Findings The results show that a self-lubricating layer with the main composition of H3BO3 was successfully fabricated on the surface of SiC-B4C composite ceramics by the annealing treatment in air. When the mass fraction of SiC is more than that of B4C, SiC-B4C composite ceramics show higher friction coefficients, the values of which are 0.38 for 80 Wt.%SiC-20 Wt.%B4C and 0.72 for 60 Wt.%SiC-40 Wt.%B4C, respectively. SiC-B4C composite ceramics show lower friction coefficients when the mass fraction of B4C is more than that of SiC. The low friction coefficients of 40 Wt.%SiC-60 Wt.% B4C composite ceramics (0.16) and 20 Wt.%SiC-80 Wt.% B4C composite ceramics (0.20) are attributed to the formation of a sufficient amount of H3BO3 layer, rather than the layer of silicon oxides. Originality/value This study will help to understand the friction behavior of SiC-B4C composite ceramics with different ratios of SiC to B4C treated by annealing in air.

Fabrication and Investigation on the Polyimide/Al2O3 Composite Films via Ion Exchange Technology

2021 ◽  
Vol 871 ◽  
pp. 264-270
Author(s):  
Ming Yu Zhang ◽  
Ya Wang ◽  
Li Zhu Liu ◽  
Wei Song ◽  
Chun Qi Zhang
Keyword(s):  
Ion Exchange ◽  
Breakdown Strength ◽  
Composite Films ◽  
Interface Layer ◽  
Polyimide Films ◽  
Hydrolysis Time ◽  
Alumina Layer ◽  
Pristine Film ◽  
Better Than ◽  
Exchange Technique

Polyimide/Al2O3 films were prepared by the surface modification with different hydrolysis time, ion exchange technique and heat treatment using polyimide films as the substrates and aluminum chloride as the precursor of Al2O3. The morphology, thermal properties and electrical properties of the composite films were characterized and tested. The results indicated the alumina distributed in certain thickness on the surface of the films and there was a clear interface layer between the alumina layer and the substrate. The breakdown strength of the composite films maintains the excellent properties of the pristine film while the thermal and corona-resistant time properties of composite films were better than the pristine film due to introducing aluminum oxide. The composite film which used KOH to treat for 90 min has the longest corona-resistant time (101.2 min), which was almost 10 times longer than the pristine film.

Ultrahigh Energy Storage Performances of Polymer-based Nanocomposite via Interfaces Engneering

2020 ◽  
Author(s):  
Peng Wang ◽  
Zhongbin Pan ◽  
Weilin Wang ◽  
Jianxu Hu ◽  
Jinjun Liu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Energy Storage ◽  
High Performance ◽  
Breakdown Strength ◽  
Composite Films ◽  
Power Electronic ◽  
Ultrahigh Energy

High-performance electrostatic capacitors are in urgent demand owing to the rapidly development of advanced power electronic applications. However, polymer-based composite films with both high breakdown strength (Eb) and dielectric constant...

Evaluation of the influence of ambient air temperature and air velocity on mortar cement durability using a forced convection solar dryer

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Younes Bahammou ◽  
Mounir Kouhila ◽  
Haytem Moussaoui ◽  
Hamza Lamsyehe ◽  
Zakaria Tagnamas ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Forced Convection ◽  
Air Temperature ◽  
Building Materials ◽  
Ambient Air ◽  
Physical Significance ◽  
Drying Process ◽  
Air Velocity ◽  
Content Type ◽  
Ambient Air Temperature

PurposeThis work aims to study the hydrothermal behavior of mortar cement toward certain environmental factors (ambient air temperature and air velocity) based on its drying kinetics data. The objective is to provide a better understanding and controlling the stability of mortar structures, which integrate the sorption phenomenon, drying process, air pressure and intrinsic characteristics. This leads to predict the comportment of mortar structures in relation with main environmental factors and minimize the risk of cracking mortar structures at an early age.Design/methodology/approachThermokinetic study was carried out in natural and forced convection solar drying at three temperatures 20, 30 and 40°C and three air velocities (1, 3 and 5 m.s-1). The empirical and semiempirical models tested successfully describe the drying kinetics of mortar. These models simulate the drying process of water absorbed by capillarity, which is the most common humidity transfer mechanism in building materials and contain parameters with physical significance, which integrate the effect of several environmental factors and intrinsic characteristics of mortar structures.FindingsThe models simulate the drying process of water absorbed by capillarity, which is the most common humidity transfer mechanism in building materials and contain parameters with physical significance, which integrate the effect of several environmental factors and intrinsic characteristics of mortar structures. The average activation energy obtained expressed the temperature effect on the mortar diffusivity. The drying constant and the diffusion coefficient can be used to predict the influence of these environmental factors on the drying behavior of various building materials and therefore on their durability.Originality/valueEvaluation of the effect of several environmental factors and intrinsic characteristics of mortar structures on their durability.

Sign in / Sign up

Export Citation Format

Share Document