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Sample records for kapton polyimide film

  1. Stopping powers and energy loss straggling for (0.9-3.4) MeV protons in a kapton polyimide thin film

    Science.gov (United States)

    Damache, S.; Djaroum, S.; Ouichaoui, S.; Amari, L.; Moussa, D.

    2016-09-01

    The energy loss and energy loss straggling widths have been measured in transmission for Ep ≈ (0.9-3.4) MeV protons traversing a thin kapton polyimide foil. In a prior step, the thickness and non-uniformity of the target foil were carefully investigated. The overall relative uncertainties in the stopping power and energy loss straggling variance data amount, respectively, to less than 2% and 8%. The S(E) experimental data show to be in excellent agreement with available previous ones and with those compiled in the ICRU-49 report. They are fully consistent with the predictions of Sigmund-Schinner's binary collision theory of electronic stopping over the whole proton energy range explored. An average deviation of ∼2.5% relative to values calculated by the SRIM-2008 code, likely due to effects of valence electrons involving the Csbnd H, Cdbnd C and Cdbnd O bonds, is however observed at low proton velocities. The measured energy loss straggling data, which are unique to our knowledge, are found to be in good agreement with values derived by the classical Bohr formula for Ep ≳ 1300 keV but they significantly exceed Bohr's collisional energy loss straggling at lower proton velocities where target electrons can no longer be considered as free. They also show to be consistent with the predictions of the Bethe-Livingston and Sigmund-Schinner theories over the low proton velocity region (Ep 1300 keV, while deviations above the latter amounting up to ∼18% are observed at lower proton velocities.

  2. Stopping powers and energy loss straggling for (0.9–3.4) MeV protons in a kapton polyimide thin film

    Energy Technology Data Exchange (ETDEWEB)

    Damache, S. [Division de Physique, CRNA, 02 Bd. Frantz Fanon, B.P. 399 Alger-gare, Algiers (Algeria); Djaroum, S. [Division de Technologie Nucléaire, CRNB, B.P. 180 Ain-Oussara, Djelfa (Algeria); Ouichaoui, S., E-mail: souichaoui@gmail.com [Université des Sciences et Technologie H. Boumediene (USTHB), Faculté de Physique, B.P. 32, 16111 Bab-Ezzouar, Algiers (Algeria); Amari, L.; Moussa, D. [Université des Sciences et Technologie H. Boumediene (USTHB), Faculté de Physique, B.P. 32, 16111 Bab-Ezzouar, Algiers (Algeria)

    2016-09-15

    The energy loss and energy loss straggling widths have been measured in transmission for E{sub p} ≈ (0.9–3.4) MeV protons traversing a thin kapton polyimide foil. In a prior step, the thickness and non-uniformity of the target foil were carefully investigated. The overall relative uncertainties in the stopping power and energy loss straggling variance data amount, respectively, to less than 2% and 8%. The S(E) experimental data show to be in excellent agreement with available previous ones and with those compiled in the ICRU-49 report. They are fully consistent with the predictions of Sigmund-Schinner’s binary collision theory of electronic stopping over the whole proton energy range explored. An average deviation of ∼2.5% relative to values calculated by the SRIM-2008 code, likely due to effects of valence electrons involving the C−H, C=C and C=O bonds, is however observed at low proton velocities. The measured energy loss straggling data, which are unique to our knowledge, are found to be in good agreement with values derived by the classical Bohr formula for E{sub p} ≳ 1300 keV but they significantly exceed Bohr’s collisional energy loss straggling at lower proton velocities where target electrons can no longer be considered as free. They also show to be consistent with the predictions of the Bethe-Livingston and Sigmund-Schinner theories over the low proton velocity region (E{sub p} < 1300 keV). However, they are significantly overestimated by these theories over the intermediate and high proton velocity regions, which may be due to bunching effect by inner shell electrons of the polymer target. Besides, our energy loss straggling data are in better overall consistency with the Yang, O’Connor and Wang empirical formula for E{sub p} > 1300 keV, while deviations above the latter amounting up to ∼18% are observed at lower proton velocities.

  3. Polyimide Aerogel Thin Films

    Science.gov (United States)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  4. Modifications in physico-chemical properties of 100 MeV oxygen ions irradiated polyimide Kapton-H polymer

    Science.gov (United States)

    Gupta, Sanjeev Kumar; Gupta, Rashi; Singh, Paramjit; Kumar, Vikas; Jaiswal, Manoj Kumar; Chakarvarti, S. K.; Kumar, Rajesh

    2017-09-01

    The optical, structural and chemical properties of polyimide Kapton-H polymer thin film samples were modified by irradiation with 100 MeV O7+ ions (in the fluence range of 1 × 1011 to 5 × 1012 ions/cm2) and the modifications of these properties were observed by UV-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy respectively. The band gap energy of the polymer decreased considerably with discrete increment of the ion fluence (different fluence for each sample) and effective change for the sample irradiated at a fluence of 5 × 1012 ions/cm2 was observed from that of pristine sample. The amorphous nature of the polymer was observed to be decreased with increase of ion fluence. The vibrations of Ctbnd C appeared at mid fluences but the stretching vibrations of Osbnd H bond disappeared at these fluences due to the high LET of the oxygen ions.

  5. Enhancement of electrical properties of polyimide films by plasma treatment

    Science.gov (United States)

    Meddeb, A. Barhoumi; Ounaies, Z.; Lanagan, M.

    2016-04-01

    In this study, the effect of oxygen plasma treatment on the electrical and surface properties of polyimide, Kapton HN, film is investigated. The plasma treatment led to an increase in the oxygen presence on the polyimide surface and a marked surface hydrophilicity. The plasma treatment led to an increase in the dielectric breakdown and Weibull modulus as well as a remarkable reduction in the scatter of all electrical measurements. There is a significant reduction in the high field/high temperature leakage current after plasma treatment. These findings have important implications in the development and improvement of dielectric polymer capacitors.

  6. Study on the mechanical property of polyimide film in space radiation environments

    Science.gov (United States)

    Shen, Zicai; Mu, Yongqiang; Ding, Yigang; Liu, Yuming; Zhao, Chunqing

    2016-01-01

    Polyimide films are widely used in spacecraft, but their mechanical properties would degrade in space environments, such as electron, proton, near ultraviolet or far ultraviolet, etc. The mechanical property and mechanism of polyimide film in electron, proton, near ultraviolet and far ultraviolet was studied by Φ800 combined space radiation test facility of Beijing Institute of Space Environment Engineering (BISSE. Rupture elongation of Kapton film decrease with the increase of the tensile deformation rate. The tensile strength and the rupture elongation of Kapton film decrease with the increase of electron and proton radiation, while tensile strength and the rupture elongation of Kapton film decrease firstly and then increase with near ultraviolet and far ultraviolet.

  7. Synthesis and Characterization of Space-Survivable POSS-Kapton (Trademark) Polyimides (Preprint)

    Science.gov (United States)

    2007-03-06

    5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sandra J. Tomczak, Timothy K. Minton, Amy L. Brunsvold, Vandana Vij, Michael E. 5d. PROJECT NUMBER...Si8O11 MC-POSS PI, and silica-coated Kapton HN® (provided by Astral Technology Unlimited, Inc. Lot No. 00625-007, with a 130 nm SiO2 coating) were...Kapton H®, (b) SiO2 coated Kapton HN® (Provided by Astral Industries Inc.), and (c) 8.75 wt % Si8O11 cage MC-POSS-PI. Samples were exposed to 2.3 x

  8. Ion bombardment of polyimide films

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, B. J.; Vasile, M. J.

    1989-07-01

    Surface modification techniques such as wet chemical etching, oxidizing flames, and plasma treatments (inert ion sputtering and reactive ion etching) have been used to change the surface chemistry of polymers and improve adhesion. With an increase in the use of polyimides for microelectronic applications, the technique of ion sputtering to enhance polymer-to-metal adhesion is receiving increased attention. For this study, the argon-ion bombardment surfaces of pyromellitic dianhydride and oxydianiline (PMDA--ODA) and biphenyl tetracarboxylic dianhydride and phenylene diamine (BPDA--PDA) polyimide films were characterized with x-ray photoelectron spectroscopy (XPS) as a function of ion dose. Graphite and high-density polyethylene were also examined by XPS for comparison of C 1/ital s/ peak width and binding-energy assignments. Results indicate that at low ion doses the surface of the polyimide does not change chemically, although adsorbed species are eliminated. At higher doses the chemical composition is altered and is dramatically reflected in the C 1/ital s/ spectra where graphiticlike structures become evident and the prominent carbonyl peak is reduced significantly. Both polyimides demonstrate similar chemical changes after heavy ion bombardment. Atomic composition of PMDA--ODA and BPDA--PDA polymers are almost identical after heavy ion bombardment.

  9. Ultraviolet laser ablation of polyimide films

    Science.gov (United States)

    Srinivasan, R.; Braren, B.; Dreyfus, R. W.

    1987-01-01

    Pulsed laser radiation at 193, 248, or 308 nm can etch films of polyimide (DuPont KaptonTM). The mechanism of this process has been examined by the chemical analysis of the condensible products, by laser-induced fluorescence analysis of the diatomic products, and by the measurement of the etch depth per pulse over a range of fluences of the laser pulse. The most important product as well as the only one condensible at room temperature is carbon. Laser-induced fluorescence analysis showed that C2 and CN were present in the ablation plume. At 248 nm, even well below the fluence threshold of 0.08 J/cm2 for significant ablation, these diatomic species are readily detected and are measured to leave the polymer surface with translational energy of ˜5 eV. These results, when combined with the photoacoustic studies of Dyer and Srinivasan [Appl. Phys. Lett. 48, 445 (1986)], show that a simple photochemical mechanism in which one photon or less (on average) is absorbed per monomer is inadequate. The ablation process must involve many photons per monomer unit to account for the production of predominantly small (<4 atoms) products and the ejection of these fragments at supersonic velocities.

  10. Evaluation of structure and mechanical properties of Ni-rich NiTi/Kapton composite film

    Energy Technology Data Exchange (ETDEWEB)

    Mohri, Maryam [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); PouryazdanPanah, Mohsen; Hahn, Horst [Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Joint Research Labaratory Nanomaterials, Technische Universität Darmstadt, Darmstadt (Germany)

    2016-06-21

    NiTi thin films are usually sputtered on silicon wafers by magnetron sputtering. But the systems composed of thin film on flexible polymeric substrate are used in many applications such as micro electro-mechanical systems (MEMS). Investigation on mechanical properties of thin films has attracted much attention due to their widespread applications. In this paper, the mechanical properties of 1 µm-thick crystallized Ni-49.2 at%Ti thin film alloy deposited by DC magnetron sputtering on Kapton substrate are investigated by using tensile test. The as-deposited thin films are in amorphous state, then for crystallization, the thin film was annealed at 450 °C for 30 min. Formation of the austenite phase after annealing was confirmed by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The surface morphology of as deposited and crystallized thin films were examined by scanning electron microscopy (SEM). Stress-strain curves of the NiTi alloy thin film were obtained by subtracting of the stress-strain Kapton curves from the corresponding curves of the NiTi/Kapton composite. The XRD results revealed that the NiTi thin film deposited on the Kapton is austenitic and presents super-elastic effect at room temperature. This pseudo elastic effect leads to more recoverable strain in NiTi/Kapton composite film compared with Kapton foils on loading/unloading test. Furthermore, it was concluded that nanostructure of the NiTi thin film is responsible for remarkable improvement of ultimate tensile strength (1.4 GPa) at a strain of 30% compared with the bulk material.

  11. Tunable biaxial in-plane compressive strain in a Si nanomembrane transferred on a polyimide film

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Munho; Mi, Hongyi; Cho, Minkyu; Seo, Jung-Hun; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Zhou, Weidong [Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Gong, Shaoqin [Department of Biomedical Engineering and Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States)

    2015-05-25

    A method of creating tunable and programmable biaxial compressive strain in silicon nanomembranes (Si NMs) transferred onto a Kapton{sup ®} HN polyimide film has been demonstrated. The programmable biaxial compressive strain (up to 0.54%) was generated utilizing a unique thermal property exhibited by the Kapton HN film, namely, it shrinks from its original size when exposed to elevated temperatures. The correlation between the strain and the annealing temperature was carefully investigated using Raman spectroscopy and high resolution X-ray diffraction. It was found that various amounts of compressive strains can be obtained by controlling the thermal annealing temperatures. In addition, a numerical model was used to evaluate the strain distribution in the Si NM. This technique provides a viable approach to forming in-plane compressive strain in NMs and offers a practical platform for further studies in strain engineering.

  12. The effect of polyimide imidization conditions on adhesion strength of thin metal films on polyimide substrates

    CERN Document Server

    Yoo, S H

    1999-01-01

    The effects of Ar sup + RF plasma precleaning and polyimide curing conditions on the peel strength between Al thin films and polyimides have been studied. The BPDA-PDA polyimide precursor of PI-2611 (Du pont) was spin-coated and cured under various imidization conditions. The cured polyimide substrates were in-situ AR sup + RF plasma cleaned prior to metal deposition. Al-1 % Si-0.5 % Cu thin films were deposited onto the polyimide substrates by using DC magnetron sputtering. The peel strength was enhanced by Ar sup + RF plasma precleaning. The Al/modified PI specimen failed cohesively in the polyimide. The polyimide curing conditions strongly affect the peel strength in the Al/modified PI system.

  13. Preparation and characterization of crystalline titania film on polyimide substrate by SILAR

    Science.gov (United States)

    Shi, Yaping; Wu, Yiyong; Sun, Chengyue; Huo, Mingxue

    2014-10-01

    Crystalline titania films were prepared on the flexible polyimide (Kapton) substrates using the successive ionic layer adsorption and reaction (SILAR) technique modified with mixed organic amine template agents at room temperature. The titania film with the organic amine template agents presents orderly stacked morphology with cross linked V-shaped strips, and it composes of mainly anatase and minor rutile phases with N doping. Structural and morphology analysis indicates that there includes two parallel deposition growth processes: One is adsorption of the template agents and reaction with Ti4+ ions on the constraint region; and the other is a normal SILAR process of including the adsorption of Ti4+ ions and reaction with hydroxyl groups. The organic amine templates and their specific adsorption induce and direct the crystallization of the titania films. Crystal structure of the titania film was confirmed by its excellent photo catalytic property of the films, detected by the degradation test of MB.

  14. Synthesis of tin-containing polyimide films

    Science.gov (United States)

    Ezzell, S. A.; Taylor, L. T.

    1984-01-01

    A series of tin-containing polyimide films derived from either 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride or pyromellitic dianhydride and 4,4'-oxydianiline have been synthesized and their electrical properties examined. Highest quality materials (i.e., homogeneous, smooth surface, flexible) with the best electrical properties were doped with either SnCl2.2H2O or (n-Bu)2SnCl2. In all cases, extensive reactivity of the tin dopant with water, air or polyamic acid during imidization is observed. Lowered electrical surface resistivities appear to be correlatable with the presence of surface tin oxide on the film surface.

  15. Electrical conduction of polyimide films prepared from polyamic acid (PAA and pre-imidized polyimide (PI solution

    Directory of Open Access Journals (Sweden)

    2007-07-01

    Full Text Available Electrical conduction characteristics in two different polyimide films prepared by the imidization of polyamic acid (PAA and pre-imidized polyimide (PI solution were investigated. It is found that the current density of the polyimide film from PAA was higher than that of the polyimide film from PI at the same electric field, even though the conduction mechanism in both polyimide films follows the ionic hopping model. The hopping distance was calculated to be 2.8 nm for PAA type and 3.2 nm for PI type polyimide film. It is also found that the decay rate of the residual electrostatic charges on the polyimide films becomes faster in the PAA type than in the PI type polyimide film.

  16. Comparison of the Results of MISSE 6 Atomic Oxygen Erosion Yields of Layered Kapton H Films with Monte Carlo Computational Predictions

    Science.gov (United States)

    Banks, Bruce A.; Groh, Kim De; Kneubel, Christian A.

    2014-01-01

    A space experiment flown as part of the Materials International Space Station Experiment 6B (MISSE 6B) was designed to compare the atomic oxygen erosion yield (Ey) of layers of Kapton H polyimide with no spacers between layers with that of layers of Kapton H with spacers between layers. The results were compared to a solid Kapton H (DuPont, Wilmington, DE) sample. Monte Carlo computational modeling was performed to optimize atomic oxygen interaction parameter values to match the results of both the MISSE 6B multilayer experiment and the undercut erosion profile from a crack defect in an aluminized Kapton H sample flown on the Long Duration Exposure Facility (LDEF). The Monte Carlo modeling produced credible agreement with space results of increased Ey for all samples with spacers as well as predicting the space-observed enhancement in erosion near the edges of samples due to scattering from the beveled edges of the sample holders.

  17. Vapor Phase Deposition and Growth of Polyimide Films on Copper.

    Science.gov (United States)

    1987-11-10

    than by spin coating procedures opens the possibility of simplified or alternate manufacturing steps in the microelectronic industry. It is necessary...the sub- strate by spin coating . The initial spin-coated layer consists of a solution of the polyimide precursor polyamic acid (PAA) dissolved in a...polyimide inter- face is spin coating the polymer precursor (PAA) onto a supported metal film, prior to curing and the formation of polyimide. Bulk

  18. Neurite outgrowth on fluorinated polyimide film micropatterned by ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, Y.; Sato, M.; Nagaoka, S.; Kawakami, H. E-mail: kawakami-hiroyoshi@c.metro-u.ac.jp; Suzuki, Y.; Iwaki, M

    2003-05-01

    In this study, we investigated neurite outgrowth on a fluorinated polyimide film micropatterned by ion irradiation. We used the fluorinated polyimide because of its excellent thermal and mechanical properties and biocompatibility. Rattus norvegicus chromaphin (PC12) cells were used for in vitro studies. The polyimide films were irradiated with He{sup +}, Ne{sup +} or Kr{sup +} at 1 x 10{sup 14} ions/cm{sup 2} using an ion-beam mask. The lines in the mask were 120 and 160 {mu}m wide and 120-160 {mu}m apart. PC12 cells were selectively adhered on the polyimide film micropatterned by Kr{sup +}-irradiation. However, the neurite length on the film irradiated by Kr{sup +} was shorter than that determined in the film irradiated by He{sup +}. On the other hand, neurite outgrowth on the polyimide film micropatterned by He{sup +}-irradiation was at least 100 {mu}m in length. This initial study indicated the enhanced outgrowth of PC12 cells on the fluorinated polyimide film micropatterned by ion irradiation.

  19. Preparation and characterization of polyimide/silica/silver composite films

    Institute of Scientific and Technical Information of China (English)

    Ning LUO; Zhanpeng WU; Nanxiang MOU; Lizhong JIANG; Dezhen WU

    2008-01-01

    Polyimide/silica/silver hybrid films were pre-pared by the sol-gel method combined with in situ single-stage self-metallization technique.The structure of polyi-mide films in the thermal curing process and the influence of silica content on the migration and aggregation of silver particles to the surface of hybrid films were investigated.The hybrid films were characterized by transmission elec-tron microscopy,dynamic mechanical thermal analysis,Fourier transform infrared spectroscopy,ultraviolet visible spectroscopy and mechanical measurements.The results indicated that there was no degradation of the polyimide matrix after the formation of silica and silver particles.Silica acted as the nucleus for the silver particles.With increasing silica content,more and more silver particles were kept in the hybrid films instead of being migrated onto the surface of the hybrid films and the reflections of hybrid films decreased gradually.

  20. Film adhesion in amorphous silicon solar cells

    Indian Academy of Sciences (India)

    A R M Yusoff; M N Syahrul; K Henkel

    2007-08-01

    A major issue encountered during fabrication of triple junction -Si solar cells on polyimide substrates is the adhesion of the solar cell thin films to the substrates. Here, we present our study of film adhesion in amorphous silicon solar cells made on different polyimide substrates (Kapton VN, Upilex-S and Gouldflex), and the effect of tie coats on film adhesion.

  1. Formation of energetic heavy ion tracks in polyimide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Deslandes, Alec, E-mail: acd@ansto.gov.au [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC 2234, NSW (Australia); Murugaraj, Pandiyan; Mainwaring, David E. [Faculty of Life and Social Sciences, Swinburne University of Technology, Hawthorn 3122, VIC (Australia); Ionescu, Mihail; Cohen, David D.; Siegele, Rainer [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC 2234, NSW (Australia)

    2013-11-01

    Highlights: •Ion tracks formed in polyimide via irradiation with high energy heavy ions. •Complementary techniques track the changes in composition of polyimide during irradiation. •Ion beam analysis aids the identification of signals from residual gas analysis. •A multi-step process of polyimide modification is observed and modelled. •The multi-step process is related to ion track density and overlap. -- Abstract: Polyimide thin films have been irradiated with a high energy beam of heavy ions to a fluence of approximately 4 × 10{sup 13} ions/cm{sup 2}. Proton backscattering spectroscopy was used to measure the composition of the films, which showed that oxygen was the element that exhibited the most rapid loss from the film. The gases evolved from the film during polymer modification were monitored using a quadrupole mass spectrometer for residual gas analysis (RGA). The fluence dependence of RGA signals were indicative of multi-step processes of gas release, whereby the passage of an ion through a region of pristine film changes the local molecular structure to one that will more readily form volatile species when subsequent ions pass.

  2. Polyimide/metal composite films via in situ decomposition of inorganic additives - Soluble polyimide versus polyimide precursor

    Science.gov (United States)

    Rancourt, J. D.; Porta, G. M.; Moyer, E. S.; Madeleine, D. G.; Taylor, L. T.

    1988-01-01

    Polyimide-metal oxide (Co3O4 or CuO) composite films have been prepared via in situ thermal decomposition of cobalt (II) chloride or bis(trifluoroacetylacetonato)copper(II). A soluble polyimide (XU-218) and its corresponding prepolymer (polyamide acid) were individually employed as the reaction matrix. The resulting composites exhibited a greater metal oxide concentration at the air interface with polyamide acid as the reaction matrix. The water of imidization that is released during the concurrent polyamide acid cure and additive decomposition is believed to promote metal migration and oxide formation. In contrast, XU-218 doped with either HAuCl4.3H2O or AgNO3 yields surface gold or silver when thermolyzed (300 C).

  3. Polymer Wall Formation Using Liquid-Crystal/Polymer Phase Separation Induced on Patterned Polyimide Films

    Science.gov (United States)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio

    2004-12-01

    We could form lattice-shaped polymer walls in a liquid crystal (LC) layer through the thermal phase separation of an LC/polystyrene solution between substrates with polyimide films etched by short-wavelength ultraviolet irradiation using a photomask. The LC wetting difference between the polyimide and substrate surfaces caused the coalescence of growing LC droplets on patterned polyimide films with the progress of phase separation. Consequently, polymer walls were formed on substrate surface areas without polyimide films. The shape of the polymer wall formed became sharp with the use of rubbed polyimide films because the nucleation of growing LC droplets concentrated on the patterned polyimide films. It is thought that the increase in the alignment order of LC molecules in the solution near the rubbed polyimide films promotes the formation of LC molecular aggregation, which becomes the growth nuclei of LC droplets.

  4. Flexible spintronic devices on Kapton

    DEFF Research Database (Denmark)

    Bedoya-Pinto, Amilcar; Donolato, Marco; Gobbi, Marco;

    2014-01-01

    of bending angle (r = 5 mm) have been achieved without degradation of the device performance, reaching room-temperature tunneling magnetoresistance ratios of 12% in bended Co/Al2O3/NiFe junctions. In addition, a suitable route to pattern high-quality nanostructures directly on the polyimide surface......Magnetic tunnel junctions and nano-sized domain-wall conduits have been fabricated on the flexible substrate Kapton. Despite the delicate nature of tunneling barriers and zig-zag shaped nanowires, the devices show an outstanding integrity and robustness upon mechanical bending. High values...... is established. These results demonstrate that Kapton is a promising platform for low-cost, flexible spintronic applications involving tunnel junction elements and nanostructurization. ...

  5. Formation of energetic heavy ion tracks in polyimide thin films

    Science.gov (United States)

    Deslandes, Alec; Murugaraj, Pandiyan; Mainwaring, David E.; Ionescu, Mihail; Cohen, David D.; Siegele, Rainer

    2013-11-01

    Polyimide thin films have been irradiated with a high energy beam of heavy ions to a fluence of approximately 4 × 1013 ions/cm2. Proton backscattering spectroscopy was used to measure the composition of the films, which showed that oxygen was the element that exhibited the most rapid loss from the film. The gases evolved from the film during polymer modification were monitored using a quadrupole mass spectrometer for residual gas analysis (RGA). The fluence dependence of RGA signals were indicative of multi-step processes of gas release, whereby the passage of an ion through a region of pristine film changes the local molecular structure to one that will more readily form volatile species when subsequent ions pass.

  6. Partly Imidized Polyamic Acid and Its Uniaxial Stretched Polyimide Films

    Institute of Scientific and Technical Information of China (English)

    MA Peng-chang; HOU Yong

    2013-01-01

    Partly imidized polyamic acid(PAA) has been used to prepare high performance polyimide films.The behaviors of two polyamic acids derived from pyromellitic dianhydride(PMDA)/4,4'-oxydianiline(ODA) and 3,Y,4,4'-biphenyltetracarboxylic diahhydride(BPDA)/paraphenylenediamine(PPD) containing dehydrating agents composed of acetic anhydride and a tertiary amine as the catalyst were investigated.The gel point was dependent on imidization degree in despite of temperature and the molar ratio of catalyst to acetic acid.Imdization content was about 35% for PMDA/ODA and about 22% for BPDA/PPD.The effect of catalyst on imidization possessed an order of triethylamine>3-methylpyridine>pyridine>isoquinoline>2-methylpyridine.The stretching of the films greatly reduced the coefficient of linear thermal expansion(CTE) either in the longitudinal direction or transversal direction.Compared to the film from polyamic acid,the partly imidized film had greater stretching ratio,so that the uniaxial stretched polyimide film from partly imidized PAA had higher tensile strength and tensile modulus,but lower elongation in the stretching direction.

  7. Preparation and characterization of polyimide/silica hybrid films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-yan; ZENG Shu-jin; DONG Tie-quan; ZHOU Sheng; FAN Yong; ZHANG Xiao-hong; LEI Qing-quan

    2006-01-01

    A kind of hybrid polyimide films was prepared by synthesizing poly( amic acid ) /Silica matrix resin through sol-gel technique and then followed by positing it on a silex glass plate and drying at high temperature.The effect of silica content on the corona-resistant property of the films was studied. The miscibility between the organic and inorganic phases and its effect on the corona-resistant property were investigated with aminopropyltriethoxysilane, which served as a coupling agent, added into the polyimide composite system. The chemical structure and the surface morphology of the films were characterized by FTIR and AFM respectively. The corona-resistant property of the films was tested by a rod-plate electrode. It proved that the corona-resistant property was enhanced with silica content. It also turned ont that the improvement of the miscibility between the two phases due to the presence of covalent force as a result of the addition of the coupling agent had, to some extent,effect on the corona-resistant property of the films. Furthermore, a theory on the corona-resistant property was put forward preliminarily.

  8. Determination of Selected Material Properties of Castable Thin Film Polyimides for Applications in Solar Thermal Propulsion

    Science.gov (United States)

    Paxton, James P.

    1994-04-01

    Partial contents; This Study will, WHat is a thin film?, An application of Thin Film polyimides, Typical Solar Thermal Rocket Configuration, Benefits of 6FDA +APB Thin Films, Design Parameters for Articles constructed with thin film polyimides, theory, thin film test apparatus, unlaxial test appartus, toggle grip design, computer test panel, experimental procedure, Modulus of Elasticity results, Coefficient of Thermal Expansion results, Conclusions and Recommendations, Acknowledgement.

  9. Surface treatment of polyimide film for metal magnetron deposition in vacuum

    Science.gov (United States)

    Petrov, V.; Vertyanov, D.; Timoshenkov, S.; Nikolaev, V.

    2014-12-01

    This paper brings forward a solution for acquisition of good quality metallization layers on the polyimide substrate by magnetron deposition in vacuum environment. Different film type structures have been analyzed after refining and activation surface treatment operations. Positive effect was shown after the application of polyimide lacquer for surface dielectric film planarization and for structural defects elimination.

  10. Ductility of copper films on sandblasting polyimide substrates

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Different surface morphologies of polyimide(PI)foils widely applied in flexible electronics were obtained using the technique of sandblasting.Copper(Cu)films were subsequently deposited on the treated surface of PI substrates.Upon tensile loading, the critical strain,crack density and count of cracks were measured to examine the ductility of Cu films on PI substrates.Obtained results show that after sandblasting treatment,the critical strain of Cu film decreases from 8.0%to 6.9%and,in comparison with the case without sandblasting,its surface crack density decreases remarkably,with no saturation of the crack density.The reduced crack density is attributed to the increase of contact area and interfacial adhesion after sandblasting,and whether the crack density is saturated or not is dependent upon the morphology of the cracks formed as a function of tensile strain.

  11. A bio-enabled maximally mild layer-by-layer Kapton surface modification approach for the fabrication of all-inkjet-printed flexible electronic devices

    Science.gov (United States)

    Fang, Yunnan; Hester, Jimmy G. D.; Su, Wenjing; Chow, Justin H.; Sitaraman, Suresh K.; Tentzeris, Manos M.

    2016-12-01

    A bio-enabled, environmentally-friendly, and maximally mild layer-by-layer approach has been developed to surface modify inherently hydrophobic Kapton HN substrates to allow for great printability of both water- and organic solvent-based inks thus facilitating the full-inkjet-printing of flexible electronic devices. Different from the traditional Kapton surface modification approaches which are structure-compromising and use harsh conditions to target, and oxidize and/or remove part of, the surface polyimide of Kapton, the present Kapton surface modification approach targeted the surface electric charges borne by its additive particles, and was not only the first to utilize environmentally-friendly clinical biomolecules to build up a thin film of protamine-heparin complex on Kapton, but also the first to be conducted under minimally destructive and maximally mild conditions. Besides, for electrically charged ink particles, the present surface modification method can enhance the uniformity of the inkjet-printed films by reducing the “coffee ring effect”. As a proof-of-concept demonstration, reduced graphene oxide-based gas sensors, which were flexible, ultra-lightweight, and miniature-sized, were fully-inkjet-printed on surface modified Kapton HN films and tested for their sensitivity to dimethyl methylphosphonate (a nerve agent simulant). Such fabricated sensors survived a Scotch-tape peel test and were found insensitive to repeated bending to a small 0.5 cm radius.

  12. Broadband dielectric spectroscopy of BPDA/ODA polyimide films

    Science.gov (United States)

    Khazaka, R.; Locatelli, M. L.; Diaham, S.; Bidan, P.; Dupuy, L.; Grosset, G.

    2013-02-01

    Dielectric spectroscopy of a high-temperature photosensitive polyimide was investigated in wide temperature and frequency ranges during heating and cooling cycles (from -150 to 370 °C and from 0.1 to 1 MHz). During the heating phase measurements two sub-glass relaxation processes were observed, noted as γ and β relaxations. The γ relaxation appears at a low temperature (around -60 °C at 1 kHz) with an activation energy of 0.44 eV during the heating phase and disappears during the cooling one, indicating that the peak is initially related to the presence of water in the polyimide films. The β relaxation appears at higher temperatures (around 180 °C at 1 kHz) with a higher activation energy of about 1.5 eV. The β peak location and intensity for low temperatures (between 100 °C and 120 °C) change slightly on comparing the heating and cooling spectra, indicating also the effect of water molecules, which may act as a plasticizer. However, for higher temperatures, the β peak does not show any significant effect of the thermal cycle, and the relaxation is mainly attributed to the non-cooperative relaxation of the polyimide molecules. The ac conductivity (σ‧) values show that the electronic hopping process is influenced by the dynamics of the segmental and macromolecular chains of the polyimide in the γ and β relaxation regions. At high temperatures (>250 °C) a plateau region appears in the ac conductivity allowing the extraction of the dc conductivity values, which are not affected between the heating and cooling measurements. This leads us to conclude that there are no significant morphological or chemical changes in the polyimide even for temperatures higher than its glass transition one under N2 for short periods. For temperatures above 300 °C an increase in the values of relative permittivity is observed and referred to the Maxwell-Wagner-Sillars or to the electrode polarization phenomena. In this range the activation energy of the polarization peak

  13. Degradation Mechanism of Polyimide Film Under Square Impulse Voltages

    Institute of Scientific and Technical Information of China (English)

    LUO Yang; WU Guangning; XIA Jinfeng; ZHU Guangya; WANG Peng; CAO Kaijiang

    2013-01-01

    Partial discharge (PD) under a sequence of high-repetition-rate square pulses is one of the key factors leading to premature failure of insulation systems of inverter-fed motors.Polyimide (PI) film is an important type of insulating material used in the inverter-fed motors.In this paper,micro-morphology and structure change of PI film aged by bipolar continuous square impulse voltage (BCSIV) with amplitude above partial discharge inception voltage (PDIV) are investigated by scanning electron microscope (SEM).The chemical bonds of PI chain are analyzed through Fourier transform infrared spectroscopy (FTIR).The results show that the degradation mechanism of PI film is the fracturing of chemical bonds caused by the erosion from PDs.Three layers are displayed in both 100 HN film and 100 CR film.The degradation path of PI film is initiated from surface and then gradually extends to the interior with continuous aging.Nano-fillers can retard the degradation of PI film and prolong its lifetime.

  14. Fragmentation and adhesion properties of CoFeB thin films on polyimide substrate

    Science.gov (United States)

    Faurie, D.; Zighem, F.; Garcia-Sanchez, A.; Lupo, P.; Adeyeye, A. O.

    2017-02-01

    We have studied the electro-mechanical properties of 20 nm thick CoFeB thin films deposited on Kapton® substrate by electrical resistivity measurements and atomic force microscopy observations during in situ tensile tests. We show in this paper that the amorphous CoFeB thin film has a brittle behavior with crack initiation at 1.6%. Moreover, the partial reversibility of the resistivity curve depends on the maximum applied strain because of the plastic deformation of the Kapton® up to 5%. Finally, the adhesion energy between CoFeB and Kapton® has been estimated from the geometry of buckling induced by the transverse compressive stress occurring during the fragmentation test. This study shows that adhesion is good enough for considering this system for potential applications in flexible spintronics applications.

  15. Applicability of Polyimide Films as Etched-Track Detectors for Ultra-Heavy Cosmic Ray Components

    Science.gov (United States)

    Yamauchi, Tomoya; Matsukawa, Kenya; Mori, Yutaka; Kanasaki, Masato; Hattori, Atsuto; Matai, Yuri; Kusumoto, Tamon; Tao, Akira; Oda, Keiji; Kodaira, Satoshi; Konishi, Teruaki; Kitamura, Hisashi; Yasuda, Nakahiro; Barillon, Rémi

    2013-04-01

    The track registration property in polyimide Kapton has been examined for heavy ions, including 2.3 GeV Fe and 24 GeV Xe ions. Conventional track formation criteria fail to predict the thresholds of etch pit formation, while a chemical criterion stating that etchable tracks are formed when two adjacent diphenyl ethers are broken in the vicinity of the ion's trajectory should be more appropriate. Discriminative detections of ultra-heavy components in cosmic rays, such as Bi, Th, and U ions, are possible by measuring the recorded track length.

  16. UV-radiation-induced degradation of fluorinated polyimide films

    Science.gov (United States)

    Chang, Li-Hsin; Saha, Naresh C.

    1994-12-01

    Fully cured fluorinated polyimide (FPI) films with low dielectric constants ( less than or equal to 3.0) have been found to be chemically altered when exposed to UV radiation during a process integration study. This chemical modification is manifested in the loss of film thickness after it is subjected to UV radiation followed by photoresist stripping. The UV-radiation-induced surface modifications of the FPI film have been characterized by X-ray photoelectron spectroscopy (XPS). The XPS data show the presence of C=O and COO(-) sites in the FPI molecule following UV exposure. Under prolonged UV exposure in a stepper, the FPI film acts as a positive working photoresist. However, a 2 kA plasma enhanced chemically vapor-deposited oxide mask and/or a typical 12 kA photoresist mask effectively shields the FPI from UV-radiation-induced degradation. The effects of FPI on UV radiation present during other normal wafer processing steps such as plasma deposition and reactive ion-etching were also studied and found to be negligible.

  17. Optical study of dye-containing fluorinated polyimide thin films

    Science.gov (United States)

    Quaranta, A.; Carturan, S.; Maggioni, G.; Della Mea, G.; Ischia, M.; Campostrini, R.

    Thin films of dye-containing fluorinated polyimide have been obtained by adding the dye powder to the polyamic acid resin and by spin coating the resulting solution on silica and silicon substrates. 6FDA (4,4'-hexafluoroisopropylidene diphthalic anhydride) and DAB (diaminobenzophenone) have been used as precursor monomers and rhodamine B as dye. The influence of the rhodamine-B molecule on the completeness of the imidization process has been studied by coupled thermogravimetric and mass-spectrometric analyses (TG-MS) of pure and doped polyamic acid resin and by FT-IR analysis of samples before and after curing. Optical emission, excitation and absorption spectra have been collected in order to study spectroscopic and aggregation characteristics of rhodamine as a function of the deposition parameters.

  18. Dense film polyimide membranes for aggressive sour gas feed separations

    KAUST Repository

    Kraftschik, Brian

    2013-02-01

    Dense film membranes of the copolyimide 6FDA-DAM:DABA (3:2) are studied for simultaneous removal of CO2 and H2S from sour natural gas streams. Pure and mixed gas permeation as well as pure gas sorption data are reported at 35°C and pressures up to 62bar. The H2S partial pressures used are representative of highly aggressive field operations. Penetrant-induced plasticization effects are evident at feed pressures below 1bar in pure H2S feeds; sub-Tg thermal annealing is used to effectively mitigate this effect, and these annealed films are used throughout the study. Surprisingly, H2S/CH4 selectivity nearly doubles for mixed gas testing in comparison to the pure component ideal selectivity values and approaches the level of a state-of-the-art glassy polymer, cellulose acetate (CA), at H2S partial pressures above 2bar. Furthermore, permeation experiments using a 9.95% H2S, 19.9% CO2, 70.15% CH4 mixture at low feed pressures give CO2/CH4 selectivity of up to 49-over 30% greater than the pure component selectivity for 6FDA-DAM:DABA (3:2). The overall sour gas separation performance of this polyimide is comparable to high-performance rubbery polymer membranes, which have been reported for only moderate H2S partial pressure feeds, and is superior to that for CA based on a practical combined acid gas separation efficiency metric that we introduce. Finally, methods for continued development of the current polyimide membrane material for aggressive sour gas separations are presented. © 2012 Elsevier B.V.

  19. COMPENSATION EFFECT OF POLYIMIDE THIN FILMS ON NORMALLY WHITE TWISTED NEMATIC LIQUID CRYSTAL DISPLAYS

    Institute of Scientific and Technical Information of China (English)

    LI Baozhong; HE Tianbai; DING Mengxian

    1997-01-01

    The disadvantages of Normally White Twisted Nematic Liquid Crystal Display (NW-TN-LCD) were discussed. The reason that the negative birefringent polyimide thin films were used to compensate NW-TN-LCD to decrease off-axis leakage, improve contrast ratios and enlarge viewing angles' was explained in this paper. A certain polyimide thin film was taken as an example to show compensation effect on NW-TN-LCD.

  20. Engineering vapor-deposited polyimides

    Science.gov (United States)

    Tsai, Feng-Yu

    The vapor deposition polymerization (VDP) of PMDA-ODA polyimide was studied parametrically to produce microcapsules and thin films with desirable properties and quality for the Inertial Confinement Fusion (ICF) experiments. The mechanical properties and gas permeability were determined at temperatures from 10 to 573 K. The VDP polyimide possessed distinct properties including lower gas permeability and stronger tensile properties from those of solution-cast Kapton, which were attributed to the presence of cross-linking. Processing parameters determining the properties of the VDP polyimide were identified: (1) utilizing air instead of nitrogen as the atmosphere of imidization increased the permeability by 140%, lowered the activation energy for permeation, and reduced the tensile strength by 30% without affecting the Young's modulus; (2) imidizing at faster heating rates increased the permeability by up to 50% and reduced the activation energy for permeation with 50% lowered tensile strength and impervious Young's modulus; (3) bi-axial stretching increased the permeability by up to three orders of magnitude. Analyses via IR spectroscopy, X-ray diffraction, and density measurement revealed that the effects of the processing parameters were results of the modifications in the crystallinity and molecular weight. The VDP polyimide underwent minor degradation in the tensile strength and elongation at break with unaffected Young's modulus and permeability upon absorbing 120 MGy of beta-radiation. Substituting a fluorinated dianhydride monomer, 6FDA, for PMDA in the optimized VDP process yielded 6FDA-ODA polyimide microcapsules and films with 50-fold increased permeability and comparable mechanical properties. The results of this study enable the production of polyimide microcapsules that will greatly facilitate the ICF experiments, and will broaden the applications of vapor-deposited polyimides in other technology fields.

  1. Effect of ion implantation upon erosion resistance of polyimide films in space environment

    Institute of Scientific and Technical Information of China (English)

    DUO Shu-wang; LI Mei-shuan; ZHOU Yan-chun

    2006-01-01

    The atomic oxygen (AO) resistance of Si ion implanted polyimide films in the ground-based AO simulation facility was investigated by scanning electron microscopy (SEM),X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results show that at the initial stage of AO exposure the implanted sample has a small mass change,and then is stabilized. The erosion yield of the implanted polyimide film decreases by about two orders of magnitude compared with that of the polyimide film. The analysis through XPS and AES indicates that a continuous high-quality protective oxide-based (SiO2) surface layer is formed on the implanted polyimide films after the AO exposure. It can provide high-quality erosion protection for these materials. The implanted polyimide fully restores its original color and the carbonization effect disappears on the whole after AO exposure. Thermal-optical properties and surface morphology of the implanted polyimide materials are not altered. The modified materials have a markedly increased erosion resistance in AO environment.

  2. In situ deposits of copper and copper oxide containing condensation polyimide films

    Science.gov (United States)

    Porta, G. M.; Taylor, L. T.

    1987-01-01

    Novel copper-polyimide composites have been synthesized via simultaneous thermal decomposition of solid solutions of bis (trifluoroacetylacetonato) copper (II) and thermal cyclodehydration of polyimide acid. In contrast to conventional filled polymer composites which are prepared by dispersion of particles or fibers in a polymer matrix this study has yielded in general uniform Cu or CuO dispersions of very small particle size that reside near the film surface that was exposed to the atmosphere during curing. The nature of the copper deposit, the thickness of the copper deposit, and the polyimide overlayer which bonds the copper to the polymer substrate depend on the curing atmosphere used. A variety of analytical surface methods along with thermogravimetric analysis and variable temperature (surface and volume) electrical resistivity measurements have been used to characterize these thin, flexible copper doped polyimide films.

  3. Substrate Material for Holographic Emulsions Utilizing Fluorinated Polyimide Film

    Science.gov (United States)

    Gierow, Paul A. (Inventor); Clayton, William R. (Inventor); St.Clair, Anne K. (Inventor)

    1999-01-01

    A new holographic substrate utilizing flexible. optically transparent fluorinated polyimides. Said substrates have 0 extremely low birefringence which results in a high signal to noise ratio in subsequent holograms. Specific examples of said fluorinated polyimides include 6FDA+APB and 6FDA+4BDAF.

  4. Optically transparent fluoro-containing polyimide films with low dielectric permeability

    Science.gov (United States)

    Kravtsova, V.; Umersakova, M.; Iskakov, R.; Prikhodko, O.; Korobova, N.

    2014-12-01

    Optical, dielectric, thermal, physico-mechanical properties of new fluoro-containing alicyclic polyimides were investigated. High optical transparency in visible and UV ranges of the films with thickness 10-25 μm, which lower boundary was registered at 125-260 nm; as well as reflectivity index being 1.492-1.515 were recorded. Dielectric permeability was characterized with low rates and stability up to 300 °C depending on chemical structure. Polyimides were stable with heating in air up to 320-380 °C. Prepared films show break tensile at 145 MPa with elongation up to 50% due to the excellent film-forming properties. Films based on polyimides with polyaniline composition demonstrates reflectivity index 1.60.

  5. Matrix-assisted pulsed laser evaporation of polyimide thin films and the XPS study

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; LI ChengXiang; ZHANG GuoBin; SHENG LiuSi

    2008-01-01

    Compared with the traditional thin film techniques, the matrix-assisted pulsed laser evaporation (MAPLE) technique has many advantages in the deposition of polymer and organic thin films. It has a wide range of applications in many fields, such as non-linear optics, luminescent devices, electronics, various sensors. We have successfully deposited polyimide thin films by using the MAPLE technique. These films were characterized with XPS. The XPS spectra showed that the single-photon effect is obvious at low laser fluence and the chemical bonds will be broken, resulting in decomposition of the films. Contrarily, the single-photon effect will decrease and the multi-photon effect and the photothermal effect will increase at high laser fluence, resulting in the protection of the structure of the polyimide thin films and the obvious decrease in decomposition. High laser fluence is more suitable for the deposition of polymer and organic thin films than low laser fluence.

  6. Matrix-assisted pulsed laser evaporation of polyimide thin films and the XPS study

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Compared with the traditional thin film techniques, the matrix-assisted pulsed laser evaporation (MAPLE) technique has many advantages in the deposition of polymer and organic thin films. It has a wide range of applications in many fields, such as non-linear optics, luminescent devices, electronics, various sensors. We have successfully deposited polyimide thin films by using the MAPLE technique. These films were characterized with XPS. The XPS spectra showed that the single-photon effect is ob-vious at low laser fluence and the chemical bonds will be broken, resulting in decomposition of the films. Contrarily, the single-photon effect will decrease and the multi-photon effect and the photothermal effect will increase at high laser fluence, resulting in the protection of the structure of the polyimide thin films and the obvious decrease in decomposition. High laser fluence is more suitable for the deposition of polymer and organic thin films than low laser fluence.

  7. Dielectric Properties of Polyimide Hybrid Film Doped with Nano Zirconium/Aluminum Oxide%纳米锆/铝氧化物杂化聚酰亚胺薄膜的介电性能

    Institute of Scientific and Technical Information of China (English)

    袁征; 范勇; 陈昊; 韩笑笑

    2011-01-01

    采用热液法制备了一系列不同Zr和Al比例的纳米粒子分散液,用原位聚合法分别制备了无机纳米杂化聚酰亚胺薄膜,并进行了SEM分析、电气强度和耐电晕测试.结果表明:Zr和A1的掺杂比例对杂化薄膜的耐电晕寿命及击穿场强影响较大,其耐电晕寿命最大可达Kapton100CR薄膜的4倍.%A series of nano-dispersions with different ratio of Zr and Al was prepared by hydrothermal method, and the corresponding inorganic nano-hybrid polyimide films were prepared through in-situ polymerization method. The hybrid film was characterized by SEM, electric strength and corona-resistant test. The results show that the doping ratio of Al and Zr has great effects on the corona-resistant life and breakdown strength of the hybrid film, and the maximum corona-resistant life is 4 times of that of Kapton 100 CR film.

  8. Fabrication and evaluation of dispersed-Ag nanoparticles-in-polyimide thin films

    Science.gov (United States)

    Sonehara, Makoto; Watanabe, Yuki; Yamaguchi, Sota; Kato, Takanori; Yoshisaku, Yasuaki; Sato, Toshiro; Itoh, Eiji

    2017-10-01

    A thin-film common-mode filter (TF-CMF) for cell phones in the UHF band was fabricated and evaluated. The TF-CMF consisted of multiple metal–insulator–metal (MIM) capacitors and inductors. The sizes of the 0.70–1.0 GHz band-type and 1.8–2.0 GHz band-type TF-CMFs are 1,140 × 1,260 × 10.5 µm3, and 1,060 × 1,060 × 10.5 µm3, respectively. The footprint in both types of TF-CMFs is over 1 mm2. In order to miniaturize the TF-CMF, we proposed to change a polyimide-only to a polyimide with dispersed Ag nanoparticles with high permittivity in the insulator layer for the MIM capacitor of the TF-CMF. A polyimide (\\text{polyimide precursor}:\\text{toluene with dispersed Ag nanoparticles} = 100:1) thin film with dispersed high-density Ag nanoparticles has a relative permittivity of about 8, which is twice as high as that of the polyimide-only thin film. If the capacitance and distance between electrodes are the same, then the capacitor footprint may be halved.

  9. Small-Angle X-Ray Scattering Study on Nanostructures of Polyimide Films

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Xu; YIN Jing-Hua; SUN Dao-Bin; BU Wen-Bin; CHENG Wei-Dong; WU Zhong-Hua

    2010-01-01

    @@ Inorganic nanohybrid polyimide(PI)is widely applied in electrical and electronic devices for its outstanding insulating properties.Samples 100CR and 100NH are made in Dupont.Among them,100NH is a kind of pure PI films; however,100CR is a kind of inorganic nanohybrid PI/films with excellent corona-resistance.The nanostructure of PI films is investigated with small-angle x-ray scattering technique and transmission electron microscopy(TEM).

  10. Study on Polyimide/Silica Hybrid Films via Directly Intermingle Method

    Institute of Scientific and Technical Information of China (English)

    Bin ZHAO; Bao-Lin RAO

    2005-01-01

    @@ 1Introduction In recent years, polyimide hybrid materials have received considerable attention due to the dramatic improvements over their pristine state in thermal stabilities, mechanical properties and other special features by introducing only small fraction inorganic additives[1]. Polyimide/silica hybrid materials were studied mostly by sol-gel route[2]. However the storage stability of the sol resin is a practical problem and has not researched on it so far. On the other hand, nano-sized silica has been produced on a large scale and industrialized. In this paper, polyimide/siliea hybrid films were prepared via directly intermingle method. The storage stability of the sol resin, the thermal and mechanical properties of the resulting films were investigated.

  11. Effects of 3 MeV proton irradiation on the mechanical properties of polyimide films

    Science.gov (United States)

    Hill, David J. T.; Hopewell, Jefferson L.

    1996-11-01

    The effects of 3 MeV proton irradiation on the elongation to break, fracture energy and Young's Modulus have been investigated for films of Kapton and Ultem over the dose range 0-75 MGy at ambient temperature. The results have been compared with those reported by other workers for irradiation by 60Co gamma rays and 2 MeV electron beams under similar conditions, and little difference was found between the damage to the mechanical properties of the films induced by these three beam types.

  12. Low-temperature processable inherently photosensitive polyimide as a gate insulator for organic thin-film transistors

    Science.gov (United States)

    Pyo, Seungmoon; Son, Hyunsam; Choi, Kil-Yeong; Yi, Mi Hye; Hong, Sung Kwon

    2005-03-01

    We have fabricated organic thin-film transistors (OTFTs) on polyethersulfone substrate using low-temperature processable, inherently photosensitive polyimide as the gate insulator and pentacene as the active material. The polyimide was prepared through two-step reaction. The polyimide precursor, poly(amic acid), was prepared from a dianhydride and aromatic diamine through a polycondensation reaction, and subsequently converted to its corresponding polyimide by a chemical imidization. Photolithographic properties of the polyimide are investigated. The pattern resolution of the cured polyimide was about 50μm. The pentacene OTFTs with the patterned polyimide were obtained with a carrier mobility of 0.1cm2/Vs and ION/IOFF of 5×105. The OTFT characteristics are discussed in more detail with respect to the electrical properties of the photosensitive polyimide thin film. This low-temperature photopatternable polyimide paves the way for the easy and low-cost fabrication of OTFT arrays without expensive and complicated photolithography and dry etching processes.

  13. Effects of combined irradiation of 500 keV protons and atomic oxygen on polyimide films

    Science.gov (United States)

    Novikov, Lev; Chernik, Vladimir; Zhilyakov, Lev; Voronina, Ekaterina; Chirskaia, Natalia

    2016-07-01

    Polyimide films are widely used on the spacecraft surface as thermal control coating, films in different constuctions, etc. However, the space ionizing radiation of different types can alter the mechanical, optical and electrical properties of polyimide films. For example, it is well known that 20-100 keV proton irradiation causes breaking of chemical bonds and destruction of the surface layer in polyimide, deterioration of its optical properties, etc. In low-Earth orbits serious danger for polymeric materials is atomic oxygen of the upper atmosphere of the Earth, which is the main component in the range of heights of 200-800 km. Due to the orbital spacecraft velocity, the collision energy of oxygen atoms with the surface ( 5 eV) enhances their reactivity and opens additional pathways of their reaction with near-surface layers of materials. Hyperthermal oxygen atom flow causes erosion of the polyimide surface by breaking chemical bonds and forming of volatiles products (primarily, CO and CO _{2}), which leads to mass losses and degradation of material properties. Combined effect of protons and oxygen plasma is expected to give rise to synergistic effects enhancing the destruction of polyimide surface layers. This paper describes experimental investigation of polyimide films sequential irradiation with protons and oxygen plasma. The samples were irradiated by 500 keV protons at fluences of 10 ^{14}-10 ^{16} cm ^{-2} produced with SINP cascade generator KG-500 and 5-20 eV neutral oxygen atoms at fluence of 10 ^{20} cm ^{-2} generated by SINP magnetoplasmodynamics accelerator. The proton bombardment causes the decrease in optical transmission coefficient of samples, but their transmittance recovers partially after the exposure to oxygen plasma. The results of the comparative analysis of polyimide optical transmission spectra, Raman and XPS spectra obtained at different stages of the irradiation of samples, data on mass loss of samples due to erosion of the surface are

  14. Electrical and Dielectric Properties of Exfoliated Graphite/Polyimide Composite Films with Low Percolation Threshold

    Science.gov (United States)

    Yu, Li; Zhang, Yi-He; Shang, Jiwu; Ke, Shan-Ming; Tong, Wang-shu; Shen, Bo; Huang, Hai-Tao

    2012-09-01

    Exfoliated graphite/polyimide composite films were synthesized by in situ polymerization. The electrical and dielectric properties of composite films with different volume fraction of exfoliated graphite were investigated over the frequency range from 103 Hz to 3 × 106 Hz. The dielectric behavior of the composite films was investigated by percolation theory and a microcapacitor model. A low percolation threshold f c ≈ 3.1 vol.% was obtained due to the high aspect ratio of the exfoliated graphite. Both the dielectric constant and alternating-current (AC) conductivity showed an abrupt increase in the vicinity of the percolation threshold. The ultralarge enhancement of the dielectric constant near and beyond the percolation threshold was due to Maxwell-Wagner-Sillars (MWS) interfacial polarization between the exfoliated graphite and polyimide and interface polarization between the composite film and electrode.

  15. Synthesis and properties of new polyimide/clay nanocomposite films

    Indian Academy of Sciences (India)

    Yagoub Mansoori; Somayeh Shah Sanaei; Mohammad-Reza Zamanloo; Gholamhassan Imanzadeh; Seyed Vahid Atghia

    2013-10-01

    A series of polymer–clay nanocomposite (PCN) materials consisting of polyimide and typical clay were prepared by solution dispersion. Quaternary alkylammonium modified montmorillonite, Cloisite 20A, was used as organoclay. Poly(amic acid) solution was prepared fromthe reaction of benzophenone-4,4′,3,3′-tetracarboxylic dianhydride and 2-(5-(3,5-diaminophenyl)-1,3,4-oxadiazole-2-yl) pyridine in dimethylacetamide. Thermal imidization was performed on poly(amic acid)/organoclay dispersion in a regular temperature-programmed circulation oven. The study of interlayer -spacing with X-ray diffraction pattern indicates that an exfoliated structure may be present in the nanocomposite 1%. Intercalated structures were obtained at higher organoclay loadings. Nanocomposites were studied using thermogravimertic analysis and differential scanning calorimetry. Nanocomposites exhibit higher glass transition temperature and improved thermal properties compared to neat polyimide due to the interaction between polymer matrix and organoclay particles. The results are also compared with data of a similar work. Morphology study with scanning electron microscopy showed that the surface roughness in nanocomposite 1%increased with respect to pristine polyimide. Solvent uptake measurements were also carried out for the prepared materials. Maximum solvent adsorption was observed for dimethyl sulfoxide (DMSO). It was found that the solvent uptake capacity decreased with increasing clay content.

  16. Flexible amorphous oxide thin-film transistors on polyimide substrate for AMOLED

    Science.gov (United States)

    Xu, Zhiping; Li, Min; Xu, Miao; Zou, Jianhua; Gao, Zhuo; Pang, Jiawei; Guo, Ying; Zhou, Lei; Wang, Chunfu; Fu, Dong; Peng, Junbiao; Wang, Lei; Cao, Yong

    2014-10-01

    We report a flexible amorphous Lanthanide doped In-Zn-O (IZO) thin-film transistor (TFT) backplane on polyimide (PI) substrate. In order to de-bond the PI film from the glass carrier easily after the flexible AMOLED process, a special inorganic film is deposited on the glass before the PI film is coated. The TFT exhibited a field-effect mobility of 6.97 cm2V-1 s-1, a subthreshold swing of 0.248 V dec-1, and an Ion/Ioff ratio of 5.19×107, which is sufficient to drive the OLEDs.

  17. Formation of hierarchical porous graphene films with defects using a nanosecond laser on polyimide sheet

    Science.gov (United States)

    Wang, Fangcheng; Wang, Kedian; Dong, Xia; Mei, Xuesong; Zhai, Zhaoyang; Zheng, Buxiang; Lv, Jing; Duan, Wenqiang; Wang, Wenjun

    2017-10-01

    The cost of effective preparation of graphene-based nanomaterials is a challenge in high-performance flexible electrodes. We demonstrated the formation of hierarchical porous graphene (HPG) films with defects from polyimide (PI) sheets using a high repetition rate nanosecond fiber laser. The honeycomb structure with mesopores and macropores can be rapidly induced on the polyimide by the localized focused laser beam in air atmosphere. Employing laser direct writing method, the one-step synthesis and patterning of conductive HPG films were achieved directly on the surface of polyimide sheets. The results show that the unique honeycomb porous structure on HPG film is composed of few-layer graphene or graphene stacks. The lattice structure of graphene nanoplatelets contains the Stone-Wales defects. Furthermore, there are a lot of small-size graphene nanoplatelets on the surface of HPG films with high content of edge defects. These two defects can not only enhance the adsorption without compromising on high diffusivity of ions, but also contribute to the infiltration and flow of electrolyte on the surface of electrode. The proposed one-step laser direct writing technique with highly valuable suitable for developing large-scale fabrication of conductive HPG based flexible electrodes at low-cost.

  18. Atomic oxygen effects on POSS polyimides in low earth orbit.

    Science.gov (United States)

    Minton, Timothy K; Wright, Michael E; Tomczak, Sandra J; Marquez, Sara A; Shen, Linhan; Brunsvold, Amy L; Cooper, Russell; Zhang, Jianming; Vij, Vandana; Guenthner, Andrew J; Petteys, Brian J

    2012-02-01

    Kapton polyimde is extensively used in solar arrays, spacecraft thermal blankets, and space inflatable structures. Upon exposure to atomic oxygen in low Earth orbit (LEO), Kapton is severely eroded. An effective approach to prevent this erosion is to incorporate polyhedral oligomeric silsesquioxane (POSS) into the polyimide matrix by copolymerizing POSS monomers with the polyimide precursor. The copolymerization of POSS provides Si and O in the polymer matrix on the nano level. During exposure of POSS polyimide to atomic oxygen, organic material is degraded, and a silica passivation layer is formed. This silica layer protects the underlying polymer from further degradation. Laboratory and space-flight experiments have shown that POSS polyimides are highly resistant to atomic-oxygen attack, with erosion yields that may be as little as 1% those of Kapton. The results of all the studies indicate that POSS polyimide would be a space-survivable replacement for Kapton on spacecraft that operate in the LEO environment.

  19. Electromigration study of Al thin films deposited on low dielectric polyimide and SiO sub 2 ILD

    CERN Document Server

    Eun, B S

    1999-01-01

    The electromigration characteristics of Al-1 %Si-0.5 %Cu films deposited onto three kinds of polyimides (PI-2734, PI-2611, and BG-2480) and onto SiO sub 2 prepared by low pressure chemical vapor deposition have been investigated. The Al lines deposited onto SiO sub 2 showed about a one-order higher electromigration lifetime than those deposited onto polyimide interlayer dielectrics (ILDs). The electromigration characteristics degraded as the polyimide thickness increased. Joule heat which accumulated at the Al/polyimide interface was the main cause of the decrease in the electromigration reliability because the thermal conductivity of the polyimides was about one order lower than that of SiO sub 2.

  20. Investigation of Surface Reaction and Degradation Mechanism of Kapton during Atomic Oxygen Exposure

    Institute of Scientific and Technical Information of China (English)

    Shuwang DUO; Meishuan LI; Yanchun ZHOU; Jingyu TONG; Gang SUN

    2003-01-01

    The erosion behavior of Kapton when exposed to atomic oxygen (AO) environment in the ground-based simulation facility was studied. The chemical and physical changes of sample surfaces after exposed to AO fluxes were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results indicated that Kapton underwent dramatically degradation, including much mass loss and change of surface morphologies; vacuum outgassing effect of Kapton was the key factor for initial mass loss in the course of atomic oxygen beam exposures. XPS analysis showed that the carbonyl group in Kapton reacted with oxygen atoms to generate CO2, then CO2 desorbed from Kapton surface. In addition, PMDA in the polyimide structure degraded due to the reaction with atomic oxygen of 5 eV.

  1. Comparative Assessment of Copper-Coated Kapton: Analysis of Microclad from Several Manufacturing Lots

    Energy Technology Data Exchange (ETDEWEB)

    Martz, Joseph Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Spearing, Dane Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Labouriau, Andrea [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Judge, Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kelly, Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dirmyer, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Milenski, Helen Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Patterson, Brian M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sandoval, Cynthia Wathen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Usov, Igor Olegovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Beaux, Miles Frank II [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henderson, Kevin C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Torres, Joseph Angelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Edwards, Stephanie Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vodnik, Douglas R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Keller, Jennie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mccabe, Rodney James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Livescu, Veronica [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cowan, Joseph Sarno [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aragonez, Robert J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tokash, Justin Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lawrence, Samantha Kay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Leon Brito, Neliza [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-04-03

    Microclad is a composite material consisting of a thin copper coating applied on a single side over a Kapton substrate. Kapton is the commercial designator for polyimide supplied by DuPont. Microclad is a key material in detonator manufacture and function. Detonators which utilize Microclad function when a large current applied through a thin bridge etched into the copper produces a plasma, accelerating a Kapton flyer into an explosive (PETN) pellet. The geometry and properties of the Microclad are a critical element of this process.

  2. Effects of chromophore concentration and film thickness on thermo-optic properties of electro-optic fluorinated polyimide films

    Institute of Scientific and Technical Information of China (English)

    Hongxiang Song; Chengxun Wu

    2007-01-01

    Electro-optic (EO) effect and thermo-optic (TO) effect are jointly considered on the basis of field-induced and temperature-affected perturbations of the operating point in waveguide components. TO coefficients of EO fluorinated polyimide films with side-chain azobenzene chromophore were measured by attenuatedtotal-reflection (ATR) technique at different temperatures with TE- and TM-polarized lights, respectively.It is found that the absolute values of TO coefficients increase with the increments of both chromophore concentration and film thickness, but the polarization dependence of TO coefficients increases with the increment of chromophore concentration and decreases with the increment of film thickness.

  3. Electromigration in Gold Films on Flexible Polyimide Substrates as a Self-healing Mechanism.

    Science.gov (United States)

    Putz, Barbara; Glushko, Oleksandr; Cordill, Megan J

    2016-01-02

    The study of electromigration (EM) in metallisations for flexible thin film systems has not been a major concern due to low applied current densities in today's flexible electronic devices. However, the trend towards smaller and more powerful devices demands increasing current densities for future applications, making EM a reliability matter. This work investigates EM in 50 nm Au thin films with a 10 nm Cr adhesion layer on a flexible polyimide substrate at high current densities. Results indicate that EM does occur and could be used as a self-healing mechanism for flexible electronics.

  4. Dielectric and Thermal Properties of Polyimide-Poly(ethylene oxide) Nanofoamed Films

    Science.gov (United States)

    Zhang, Yi-He; Yu, Li; Zhao, Li-Hang; Tong, Wang-Shu; Huang, Hai-Tao; Ke, Shan-Ming; Chan, H. L. W.

    2012-08-01

    Polyimide nanofoamed films have been prepared by incorporating poly(ethylene oxide) (PEO) into poly(amide acid) (PAA) precursors with subsequent imidization of PAA precursors at high temperature. The porous structure, thermal decomposition temperature, and dielectric property of nanofoamed films were investigated by scanning electron microscopy, thermogravimetric analysis, and impedance spectroscopy. Nanopores with sizes around 40 nm to 200 nm were formed in nanofoamed films by pyrolysis of PEO during the imidization progress. The decomposition temperature of nanofoamed films decreased slightly with increasing volume fraction of nanopores and maintained the high decomposition temperature of 499.7 °C when the volume fraction of nanopores was 10.9 %. The dielectric constant of nanofoamed films decreased from 3.4 for pure PI to 2.4 at 103 Hz through the introduction of nanopores with volume fraction of 10.9 %.

  5. Adhesion energies of Cr thin films on polyimide determined from buckling: Experiment and model

    Energy Technology Data Exchange (ETDEWEB)

    Cordill, M.J., E-mail: megan.cordill@oeaw.ac.at [Erich Schmid Institute of Materials Science, Austrian Academy of Sciences and Department of Material Physics, Montanuniversitaet Leoben, Leoben 8700 (Austria); Fischer, F.D. [Institute of Mechanics, Montanuniversitaet Leoben, Leoben 8700 (Austria); Rammerstorfer, F.G. [Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Vienna 1040 (Austria); Dehm, G. [Erich Schmid Institute of Materials Science, Austrian Academy of Sciences and Department of Material Physics, Montanuniversitaet Leoben, Leoben 8700 (Austria)

    2010-09-15

    For the realization of flexible electronic devices, the metal-polymer interfaces upon which they are based need to be optimized. These interfaces are prone to fracture in such systems and hence form a weak point. In order to quantify the interfacial adhesion, novel mechanical tests and modeling approaches are required. In this study, a tensile testing approach that induces buckling of films by lateral contraction of the substrate is employed to cause delamination of the film. Based on a newly developed energy balance model, the adhesion energy of Cr films on polyimide substrates is determined by measuring the buckle geometry induced by the tensile test. The obtained minimum values for the adhesion energy (about 4.5 J m{sup -2}) of 50-190 nm thick films compare well to those found in the literature for metal films on polymer substrates.

  6. Wide temperature polyimide/ZrO2 nanodielectric capacitor film with excellent electrical performance

    Science.gov (United States)

    Zou, C.; Kushner, D.; Zhang, S.

    2011-02-01

    In this letter, wide temperature dielectric properties and corona resistance of Upilex-S® polyimide (PI) films filled with Zirconium dioxide (ZrO2) nanoparticles were investigated. ZrO2/PI nanodielectrics exhibited the stable dielectric properties, high energy density and high charge-discharge efficiency below 300 °C. Testing of corona resistance showed even a small amount of nanofillers can improve the lifetime of PI significantly. Scanning electron microscopy with x-ray microanalysis (SEM-EDS) analysis suggested the higher thermal conductivity and evaporation of ZrO2 nanoparticles may induce this improvement. These high performance features make polyimide nanocomposites attractive for high energy density capacitor applications at high temperature.

  7. Comparison of the tribological properties at 25 C of seven different polyimide films bonded to 301 stainless steel

    Science.gov (United States)

    Fusaro, R. L.

    1980-01-01

    A pin-on-disk type of friction and wear apparatus was used to study the tribological properties of seven different polyimide films bonded to AISI 301 stainless steel disks at 25 C. It was found that the substrate material was extremely influential in determining the lubricating ability of the polyimide films. All seven films spalled in less than 1000 cycles of sliding. This was believed to be caused by poor adherence to the 301 stainless steel or the inability of the films to withstand the high localized tensile stresses imparted by the deformation of the soft substrate under sliding conditions. The friction coefficients obtained for six of the polyimides varied between 0.21 to 0.32 while one varied between 0.32 to 0.39.

  8. A facile method for preparing highly conductive and reflective surface-silvered polyimide films

    Science.gov (United States)

    Liao, Yuan; Cao, Bing; Wang, Wen-Cai; Zhang, Liqun; Wu, Dezhen; Jin, Riguang

    2009-07-01

    A novel method was developed for the preparation of reflective and electrically conductive surface-silvered polyimide (PI) films. The polyimide films were functionalized with poly(dopamine), simply by dipping the PI films into aqueous dopamine solution and mildly stirring at room temperature. Electroless plating of silver was readily carried out on the poly(dopamine) deposited PI (PI-DOPA) surface. The surface compositions of the modified PI films were studied by X-ray photoelectron spectroscopy (XPS). XPS results show that the PI-DOPA surfaces were successfully deposited with ploy(dopamine) and were ready for electroless deposition of silver. The poly(dopamine) layer was used not only as the chemi-sorption sites for silver particles during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The as-prepared silvered PI films show high conductivity and reflectivity, with a surface resistance of 1.5 Ω and a reflectivity of 95%, respectively.

  9. A facile method for preparing highly conductive and reflective surface-silvered polyimide films

    Energy Technology Data Exchange (ETDEWEB)

    Liao Yuan; Cao Bing [State Key Laboratory of Chemical Resource Engineering, and the Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing 100029 (China); Wang Wencai, E-mail: wangw@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, and Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing 100029 (China); Zhang Liqun; Wu Dezhen; Jin Riguang [State Key Laboratory of Chemical Resource Engineering, and Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing 100029 (China)

    2009-07-15

    A novel method was developed for the preparation of reflective and electrically conductive surface-silvered polyimide (PI) films. The polyimide films were functionalized with poly(dopamine), simply by dipping the PI films into aqueous dopamine solution and mildly stirring at room temperature. Electroless plating of silver was readily carried out on the poly(dopamine) deposited PI (PI-DOPA) surface. The surface compositions of the modified PI films were studied by X-ray photoelectron spectroscopy (XPS). XPS results show that the PI-DOPA surfaces were successfully deposited with ploy(dopamine) and were ready for electroless deposition of silver. The poly(dopamine) layer was used not only as the chemi-sorption sites for silver particles during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The as-prepared silvered PI films show high conductivity and reflectivity, with a surface resistance of 1.5 {Omega} and a reflectivity of 95%, respectively.

  10. Thermal diffusivity of aromatic polyimide thin films by temperature wave analysis

    Science.gov (United States)

    Morikawa, Junko; Hashimoto, Toshimasa

    2009-06-01

    The heat transport properties of aromatic polyimide thin films have become more important in the use for the electric insulation in the microelectronic devices with highly integrated circuits. The various kinds of measuring methods have been applied to obtain the anisotropic thermal conductivity and thermal diffusivity of thin films, however, if the specimens are soft and transparent, the conventional methodology requires highly advanced technology in preparing the specimens for the measurement and the results obtained vary widely. The purpose of this study is to apply the temperature wave analysis (TWA) method to measure the thermal diffusivity of thin films and spin-coated layers of aromatic polyimide in the thickness direction at various temperatures. The TWA is an absolute method to determine the thermal diffusivity by using the phase shift of temperature wave. We have performed measurements on the five different chemical structures of aromatic polyimide, including polyimide isoindoloquinazolinedione (PIQ), pyromellitic dianhydride and 4,4'-oxydianiline (PMDA/ODA), 3,3',4,4',-biphenyltetracarboxylic dianhydride and p-phenylenediamine (BPDA/PPDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-oxydianiline (BPDA/ODA), and 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 3,3'-diaminobenzophenone (BTDA/DAB). As a result, thermal diffusivity of thin films in a thickness range from 0.1 to 300 μm at a temperature range from 10 to 570 K is obtained. The thickness dependence of thermal diffusivity of spin-coated layers of PIQ exhibits a good coincidence with the tendency of molecular anisotropy observed by attenuated total reflection Fourier transform infrared spectroscopy. In the low temperature below 20 K the amorphous PMDA/ODA film exhibits a substantial increase, which can be understood by considering the phonon mean free path of amorphous systems as first noted by Kittel for inorganic glasses. The glass transition of BTDA/DAB is observed as a rapid

  11. Erosion of POSS-polyimide films under hypervelocity impact and atomic oxygen: The role of mechanical properties at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Verker, R. [Space Environment Group, Soreq NRC, Yavne 81800 (Israel); School of Mechanical Engineering, Tel-Aviv University, Ramat Aviv, Tel-Aviv 69978 (Israel)], E-mail: rverker@soreq.gov.il; Grossman, E. [Space Environment Group, Soreq NRC, Yavne 81800 (Israel); Eliaz, N. [School of Mechanical Engineering, Tel-Aviv University, Ramat Aviv, Tel-Aviv 69978 (Israel)

    2009-02-15

    Low Earth orbital debris impacts on the external surfaces of satellites have increased dramatically in recent years. Polyimides are used as the outer layer of thermal control insulation blankets, covering most of the external spacecraft surfaces that are exposed to the space environment. A recently developed material, named polyhedral oligomeric silsesquioxane (POSS)-polyimide, shows significant enhancement in withstanding the space environment. In this work, the combined effect of ground-simulated hypervelocity space debris impacts and atomic oxygen (AO) on the erosion of POSS-containing polyimide films was investigated. During such hypervelocity impacts, elevated temperatures, on the order of hundreds degrees, are formed. A laser-driven flyer system was used to accelerate aluminum flyers to impact velocities of up to 3 km s{sup -1}. The impacted films were exposed to an oxygen RF plasma environment, simulating the effect of AO in the low Earth orbit. Impacted polyimide films exposed to AO revealed synergistic erosion effect, while impacted POSS-containing samples showed improved erosion resistance. The increased erosion rate of the impacted polyimide film is explained by formation of residual stresses that affect the oxidation mainly by increasing the diffusivity of oxygen into the subsurface layers. Mechanical properties of the POSS-containing samples performed at 450 deg. C and fractographic examination supports the above hypothesis.

  12. Erosion effects of atomic oxygen on polyhedral oligomeric silsesquioxane-polyimide hybrid films in low earth orbit space environment.

    Science.gov (United States)

    Duo, Shuwang; Song, Mimi; Liu, Tingzhi; Hu, Changyuan; Li, Meishuan

    2013-02-01

    A novel polyimide (PI) hybrid nanocomposite containing polyhedral oligomeric silsesquioxane (POSS) had been prepared by copolymerization of trisilanolphenyl-POSS, 4,4'-oxydianiline (ODA), and pyromellitic dianhydride (PMDA). The AO resistance of these PI/POSS hybrid films was tested in the ground-based AO simulation facility. Exposed and unexposed surfaces were characterized by SEM and X-ray photoelectron spectroscopy. SEM images showed that the surface of the 20 wt% PI/POSS became much less rough than that of the pristine polyimide. Mass measurements of the samples showed that the erosion yield of the PI/POSS (20 wt.%) hybrid film was 1.2 x 10(-25) cm3/atom, and reduced to 4% of the polyimide film. The XPS data indicated that the carbon content of the near-surface region was decreased from 60.1 to 13.2 at% after AO exposure. The oxygen and silicon concentrations in the near-surface region increased to 1.96 after AO exposure. The nanometer-sized structure of POSS, with its large surface area, had led AO-irradiated samples to form a SiO2 passivation layer, which protected the underlying polymer from further AO attack. The incorporation of POSS into the polyimide could dramatically improve the AO resistance of polyimide films in low earth orbit environment.

  13. Property enchancement of polyimide films by way of the incorporation of lanthanide metal ions

    Science.gov (United States)

    Thompson, David W.

    1993-01-01

    Lanthanide metal ions were incorporated into the polyimide derived from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 1,3-bis(aminophenoxy) benzene (APB) in an attempt to produce molecular level metal-polymer composites. The lanthanide series of metal ions (including aluminum, scandium, and yttrium) provide discrete and stable metal ions in the 3+ oxidation state. Throughout the series there is a uniform variation in ionic size ranging from 50 pm for aluminum to a maximum of 103.4 pm for cerium and gradually decreasing again to 84.8 pm for lutetium. The high charge-to-size ratio for these ions as well as the ability to obtain large coordination numbers makes them excellent candidates for interacting with the polymer substructure. The distinct lack of solubility of simple lanthanide salts such as the acetates and halides has made it difficult to obtain metal ions distributed in the polymer framework as discrete ions or metal complexes rather than microcomposites of metal clusters. (Lanthanum nitrates are quite soluble, but the presence of the strongly oxidizing nitrate ion leads to serious degradation of the polymer upon thermal curing. This work was successful at extending the range of soluble metals salts by using chelating agents derived from the beta-diketones dipivaloylmethane, dibenzoylmethane, trifluoroacetylacetone, and hexafluoroacetylacetone. Metal acetates which are insoluble in dimethylacetamide dissolve readily in the presence of the diketones. Addition of the polyimide yields a homogeneous resin which is then cast into a clear film. Upon curing clear films were obtained with the dibenzoylmethane and trifluoroacetylacetone ligands. The dipavaloylmethane precipitates the metal during the film casting process, and hexafluoroacetylacetone gives cured films which are deformed and brittle. These clear films are being evaluated for the effect of the metal ions on the coefficient of thermal expansion, resistance to atomic oxygen, and on

  14. Generation of Air Microplasma Jet and Its Application to Local Etching of Polyimide Films

    Science.gov (United States)

    Yoshiki, Hiroyuki

    2006-06-01

    An air microplasma jet (air μ-PJ) was generated at the tip of a stainless steel surgical needle with outer diameters of 0.4-0.7 mm at air flow rates of 0.3-1.0 l/min and RF (13.56 MHz) powers of 4-14 W, in which the air μ-PJ was operated without generating arc discharge at atmospheric pressure. The needle acts as both a powered electrode and a narrow gas nozzle. The peak-to-peak voltages Vpp were 1.5-1.7 kV and the temperatures of the plasma-irradiated spot (φetching of polyimide films with a thickness of 0.025 mm. A polyimide etch rate of approximately 5 μm/s was attained using a 0.4-mm-φ needle electrode at a RF power of 8 W. The etching mechanism was not based on a thermal effect but on a chemical reaction of oxygen atoms. Furthermore, the local removal of a polyamide-imide insulator film coated on a copper winding wire (φfilm to a copper wire was achieved at a RF power of 7 W and plasma irradiation times of 5-20 s.

  15. Experimental demonstration of trapping waves with terahertz metamaterial absorbers on flexible polyimide films

    Science.gov (United States)

    Wang, Wei; Liu, Jinsong; Wang, Kejia

    2016-02-01

    We present the design, numerical simulations and experimental measurements of an asymmetric cross terahertz metamaterial absorber (MPA) on ultra-flexible polyimide film. The perfect metamaterial absorber composed of two structured metallic layers separated with a polyimide film with a total thickness of functional layers much smaller than the operational wavelength. Two distinct absorption peaks are found at resonance frequencies of 0.439THz and 0.759 THz with resonance amplitude of near unity, which are in good agreement with the simulation results. The sample is also measured by a THz-TDS imaging system to illustrate the absorption characterization. The scanning images show that the sample could act as a perfect absorber at specific resonance frequencies while a perfect reflector at off resonance frequencies. To illustrate the physical mechanism behind these spectral responses, the distribution of the power loss and surface current are also presented. The result shows that the incident wave is trapped and absorbed by the polyimide dielectric layer at different vicinities of the proposed asymmetric cross MPA for the two absorption peaks. Furthermore, the index sensing performance of the structure is also investigated, and the calculated sensitivity is 90GHz/RIU for f1 mode and 154.7GHz/RIU for f2 mode, indicating that the higher frequency resonance absorption peak has better potential applications in sensing and detection. The ultra-flexible, low cost, high intensity dual band terahertz absorbers may pave the way for designing various terahertz functional devices, such as ultrasensitive terahertz sensors, spatial light modulators and filters.

  16. Microwave sintering of Ag-nanoparticle thin films on a polyimide substrate

    Directory of Open Access Journals (Sweden)

    S. Fujii

    2015-12-01

    Full Text Available Ag-nanoparticle thin films on a polyimide substrate were subjected to microwave sintering by use of a single-mode waveguide applicator. A two-step sintering process was employed. First, at low conductivities of the film, the film sample was placed at the site of the maximum electric field and subjected to microwave irradiation. Second, when the conductivity of the film increased, the film sample was placed at the site of the maximum magnetic field and again subjected to microwave irradiation. The microwave sintering process was completed within 1.5 min, which is significantly lower than the time required for the oven heating process. The resulting conductivity of the film, albeit only 30% of that of the bulk material, was seven times that of a film annealed at the same temperature in a furnace. Scanning electron microscopy images revealed that the nanoparticles underwent both grain necking and grain growth during microwave sintering. In addition, this sintering process was equivalent to the oven heating process performed at a 50 °C higher annealing temperature. An electromagnetic wave simulation and a heat transfer simulation of the microwave sintering process were performed to gain a thorough understanding of the process.

  17. Microwave sintering of Ag-nanoparticle thin films on a polyimide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, S., E-mail: fujii.s.ap@m.titech.ac.jp [Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8522 (Japan); Department of Information and Communication System Engineering, National Institute of Technology, Okinawa College, Nago, Okinawa 905-2192 (Japan); Kawamura, S.; Maitani, M. M.; Suzuki, E.; Wada, Y. [Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8522 (Japan); Mochizuki, D. [Interdisciplinary Cluster for Cutting Edge Research, Center for Energy and Environmental Science, Shinshu University, Ueda, Nagano 386-8567 (Japan)

    2015-12-15

    Ag-nanoparticle thin films on a polyimide substrate were subjected to microwave sintering by use of a single-mode waveguide applicator. A two-step sintering process was employed. First, at low conductivities of the film, the film sample was placed at the site of the maximum electric field and subjected to microwave irradiation. Second, when the conductivity of the film increased, the film sample was placed at the site of the maximum magnetic field and again subjected to microwave irradiation. The microwave sintering process was completed within 1.5 min, which is significantly lower than the time required for the oven heating process. The resulting conductivity of the film, albeit only 30% of that of the bulk material, was seven times that of a film annealed at the same temperature in a furnace. Scanning electron microscopy images revealed that the nanoparticles underwent both grain necking and grain growth during microwave sintering. In addition, this sintering process was equivalent to the oven heating process performed at a 50 °C higher annealing temperature. An electromagnetic wave simulation and a heat transfer simulation of the microwave sintering process were performed to gain a thorough understanding of the process.

  18. Measurements of prompt radiation induced conductivity of Kapton.

    Energy Technology Data Exchange (ETDEWEB)

    Preston, Eric F. (ITT Corporation, Colorado Springs, CO); Zarick, Thomas Andrew; Sheridan, Timothy J.; Hartman, E. Frederick; Stringer, Thomas Arthur (ITT Corporation, Colorado Springs, CO)

    2010-10-01

    We performed measurements of the prompt radiation induced conductivity in thin samples of Kapton (polyimide) at the Little Mountain Medusa LINAC facility in Ogden, UT. Three mil samples were irradiated with a 0.5 {mu}s pulse of 20 MeV electrons, yielding dose rates of 1E9 to 1E10 rad/s. We applied variable potentials up to 2 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 6E-17 and 2E-16 mhos/m per rad/s, depending on the dose rate and the pulse width.

  19. Surface Modification of Polyimide Film by Dielectric Barrier Discharge at Atmospheric Pressure

    Science.gov (United States)

    Peng, Shi; Li, Lingjun; Li, Wei; Wang, Chaoliang; Guo, Ying; Shi, Jianjun; Zhang, Jing

    2016-04-01

    In this paper, polyimide (PI) films are modified using an atmospheric pressure plasma generated by a dielectric barrier discharge (DBD) in argon. Surface performance of PI film and its dependence on exposure time from 0 s to 300 s are investigated by dynamic water contact angle (WCA), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy in attenuated total multiple reflection mode (FTIR-ATR). The study demonstrates that dynamic WCA exhibits a minimum with 40 s plasma treatment, and evenly distributed nano-dots and shadow concaves appeared for 40 s and 12 s Ar plasma treatment individually. A short period of plasma modification can contribute to the scission of the imide ring and the introduction of C-O and C=O (-COOH) by detailed analysis of FTIR-ATR.

  20. Preparation of nanoporous polyimide thin films via layer-by-layer self-assembly of cowpea mosaic virus and poly(amic acid)

    Energy Technology Data Exchange (ETDEWEB)

    Peng Bo; Wu Guojun; Lin Yuan [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Wang Qian [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29208 (United States); Su Zhaohui, E-mail: zhsu@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China)

    2011-09-01

    Low dielectric (low-{kappa}) materials are of key importance for the performance of microchips. In this study, we show that nanosized cowpea mosaic virus (CPMV) particles can be assembled with poly(amic acid) (PAA) in aqueous solutions via the layer-by-layer technique. Then, upon thermal treatment CPMV particles are removed and PAA is converted into polyimide in one step, resulting in a porous low-{kappa} polyimide film. The multilayer self-assembly process was monitored by quartz crystal microbalance and UV-Vis spectroscopy. Imidization and the removal of the CPMV template was confirmed by Fourier transform infrared spectroscopy and atomic force microscopy respectively. The dielectric constant of the nanoporous polyimide film thus prepared was 2.32 compared to 3.40 for the corresponding neat polyimide. This work affords a facile approach to fabrication of low-{kappa} polyimide ultrathin films with tunable thickness and dielectric constant.

  1. Photoablation characteristics of novel polyimides synthesized for high-aspect-ratio excimer laser LIGA process

    Science.gov (United States)

    Yang, Chii-Rong; Hsieh, Yu-Sheng; Hwang, Guang-Yeu; Lee, Yu-Der

    2004-04-01

    The photoablation properties of two soluble polyimides DMDB/6FDA and OT/6FDA with thicknesses of over 300 µm, synthesized by the polycondensation of a hexafluoropropyl group contained in a dianhydride with two kinds of diamines, are investigated using a 248 nm krypton fluoride (KrF) laser. The incorporation of the hexafluoropropyl group into the chemical structure gives these two polyimides higher etching rates than Kapton (a commercial polyimide film which is difficult to dissolve). The etching rates of synthesized polyimides are about 0.1-0.5 µm/pulse over a fluence range of 0.25-2.25 J cm-2. The photothermal mechanism for DMDB/6FDA contributes about 19% of etching depth at a laser fluence of 0.82 J cm-2. Moreover, the number of laser pulses seriously affects the taper angle of microstructures, especially at low fluence. Near-vertical side-wall structures can be built at high fluence (~2 J cm-2). Fresnel patterns with a thickness of 300 µm and a linewidth of 10 µm were fabricated, with an attainable aspect ratio of around 30. After photoablation, the complementary metallic microstructures were also fabricated by a sequential electroplating procedure. Then, those two new polyimides could be dissolved easily in most common solvents (such as THF, DMSO, NMP and DMF). These results indicate that these two soluble polyimides are highly suitable for use in the KrF laser LIGA process.

  2. Cell fouling resistance of PEG-grafted polyimide film for neural implant applications

    Science.gov (United States)

    Heo, Dong Nyoung; Yang, Dae Hyeok; Lee, Jung Bok; Bae, Min Su; Park, Ha Na; Kwon, Il Keun

    2012-04-01

    Recently, neural prosthetic electrodes covered with polyimide (PI) have been developed for chronic recording and stimulation of nervous system function. However, when these devices are implanted onto the nerve trunk, nerves might be damaged by the presence of the electrode due to the mechanical mismatch between the stiff probe and the soft biological tissue. Consequently, newly formed tissue layer may isolate the electrode from neural tissue, resulting in poor signal detection. In this study, we found a method to solve this problem. As the method, we designed and prepared poly(ethylene glycol) (PEG)-grafted PI film to function cell fouling resistance. The PEG-grafted PI film was characterized by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements. Protein adsorption experiment was carried out to evaluate protein fouling resistance because protein adsorption is closely related to cell adhesion. In vitro cell behavior on PEG-grafted PI film was evaluated by confocal laser scanning microscopy (CLSM) and CCK assays. The results showed that PEG-grafted PI film has characteristics of protein and cell fouling resistances as compared to bare and hydrolyzed PI films under in vitro. We suggested that PEG-grafted PI film can be useful for a neural implantable electrode.

  3. Improved performances of AlN/polyimide hybrid film and its application in redistribution layer

    Science.gov (United States)

    Liu, Zhe; Ding, Guifu; Luo, Jiangbo; Lu, Wen; Zhao, Xiaolin; Cheng, Ping; Wang, Yanlei

    2016-09-01

    The AlN/polyimide (PI) hybrid film was studied as the dielectric layer in the redistribution layer (RDL) in this work. The incorporation of the AlN into the PI matrix was achieved by mechanical ball-milling process. The spin-coating process was used to fabricate the AlN/PI hybrid film, which is compatible with micro-electro-mechanical system (MEMS) technology for fabricating RDL. The AlN/PI hybrid film was characterized by Fourier transform infrared (FTIR) spectrum and thermogravimetric analysis (TGA). The effect of the AlN content on the thermal stability, thermal expansion coefficient, hardness and water adsorption of the AlN/PI hybrid film was studied. The results indicated that the addition of AlN nanoparticles improved the thermal stability and hardness, but decreased the thermal expansion coefficient and water absorption of the pure PI film. As an example of its typical application, the AlN/PI hybrid film with 8 wt.% AlN was patterned using micromachining technology and used as the dielectric layer in RDL successfully.

  4. Low-dielectric, nanoporous polyimide thin films prepared from block copolymer templating

    Directory of Open Access Journals (Sweden)

    C. Wang

    2013-08-01

    Full Text Available In this paper, a new method to the preparation of low-dielectric nanoporous polyimide (PI films was addressed, based on the self-assembly structures of PS-b-P4VP/poly(amic acid (PAA, precursor of PI blends. It is found the microphase-separation structure of PS-b-P4VP/PAA is a precondition of the formation of nanoporous structures, which could be achieved by solvent annealing. Nanoporous PI films with spherical pore size of ~11 nm were obtained by thermal imidization followed by the removal of the PS-b-P4VP block copolymer. The porosity of the nanoporous PI films could be controlled by the weight fraction of the PS-b-P4VP block copolymer. The dielectric properties of the nanoporous PI films were studied, and it was found that the introduction of nanopores could effectively reduce the dielectric constant from 3.60 of dense PI films to 2.41 of nanoporous PI films with a porosity of 26%, making it promising in microelectronic devices. The fabrication method described here could be extended to other polymer systems.

  5. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    Directory of Open Access Journals (Sweden)

    Soliman Abdalla

    2016-02-01

    Full Text Available Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of four highly pure amorphous polymer films: polymethyl methacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher breakdown performance is a character of polyimide (PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  6. Preparation,structure and properties of porous polyimide films via PAA/PU alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Jiugui; JIANG Lizhong; ZHAN Jiayu; WU Dezhen; JIN Riguang

    2007-01-01

    A new route to porous polyimide(PI)films with pore sizes in the nanometer regime was developed.A polyamic acid(PAA)/polyurethane(PU)blend with PU as the disperse phase was first prepared via in situ polymerization of pyromellitic dianhydride and 4,4-oxydianiline in PU solutions.Porous PI films were obtained from PAAJPU films by thermolysis of PU at 360℃ and imidization of PAA at 300℃,respectively.Fourier transform infrared spectroscopy and thermal gravimetric analysis were used to detect the imidization and thermolysis processes of PAA/PU blends under thermal treatment.The microporous structure of the PI films was observed by transmission electron microscopy.It was found that the size and content of pores increased with an increase in the PU mass fraction in the PAA/PU blend up to 20%.Because of the existence of nanopores,the dielectric constant of PI films decreased by a wide margin and was less than 2.0 at a PU mass fraction of 20%.It implies that this is an effective means to reduce the dielectric constant of PI,but it also causes the decrease of tensile strength and the rise of water absorption.

  7. The effect of simulated low earth orbit radiation on polyimides (UV degradation study)

    Science.gov (United States)

    Forsythe, John S.; George, Graeme A.; Hill, David J. T.; Odonnell, James H.; Pomery, Peter J.; Rasoul, Firas A.

    1995-01-01

    UV degradation of polyimide films in air and vacuum were studied using UV-visible, ESR, FTIR, and XPS spectroscopies. The UV-visible spectra of polyimide films showed a blue shift in the absorption compared to Kapton. This behavior was attributed to the presence of bulky groups and kinks along the polymer chains which disrupt the formation of a charge transfer complex. The UV-visible spectra showed also that UV irradiation of polyimides result extensively in surface degradation, leaving the bulk of the polymer intact. ESR spectra of polyimides irradiated in vacuum revealed the formation of stable carbon-centered radicals which give a singlet ESR spectrum, while polyimides irradiated in air produced an asymmetric signal shifted to a lower magnetic field, with a higher g value and line width. This signal was attributed to oxygen-cenetered radicals of peroxy and/or alkoxy type. The rate of radical formation in air was two fold higher than for vacuum irradiation, and reached a plateau after a short time. This suggests a continuous depletion of radicals on the surface via an ablative degradation process. FTIR, XPS, and weight loss studies supported this postulate. An XPS study of the surface indicated a substantial increase in the surface oxidation after irradiation in air. The sharp increase in the C-O binding energy peak relative to the C-C peak was believed to be associated with an aromatic ring opening reaction.

  8. Post annealing effects on the properties of sputtered nano-crystallite indium tin oxide thin films on flexible polyimide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi Gheidari, A.; Iraj, M.; Kazemzad, M.; Behafarid, F. [Materials and Energy Research Center (MERC), Tehran (Iran); Hadad Dabaghi, H. [Departmet of Chemistry, Islamic Azad University of Karaj, Karaj (Iran); Kalhor, D. [Department of Physics, Damghan University of Basic Sciences (Iran)

    2008-07-01

    Indium tin oxide (ITO) thin films were deposited onto flexible polyimide substrates using RF sputtering system at room temperature. The deposited films were then heat treated at different temperatures in air and vacuum atmospheres. The structural variations and as consequence the electro-optical characteristic variations of the films were systematically investigated as a function of post annealing temperature and atmosphere. The structure of the films was studied by means of XRD and SEM techniques and the electro-optical characteristics were measured by four point probe and spectrophotometer, respectively. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. SYNTHESIS AND CHARACTERIZATION OF AMINO FUNCTIONALIZED LADDER-LIKE POLYSILSESQUIOXANES AND THEIR HYBRID FILMS WITH POLYIMIDE

    Institute of Scientific and Technical Information of China (English)

    Qiu-shuang Gao; Guo-feng Tian; Sheng-li Qi; Zhan-peng Wu; De-zhen Wu

    2013-01-01

    Ladder-like polysilsesquioxanes (LPSQs) with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst.The concentration and activity of amino groups were investigated by Fourier transform infrared spectroscopy.Polyimide (PI)/LPSQ hybrid films have been prepared by incorporating of the obtained LPSQs with different amino contents into PI matrix,respectively.The interfacial interactions between PI matrix and LPSQ were studied with scanning electron microscopy and X-ray photoelectron spectroscopy,meanwhile the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests.The results indicate that the functionality of LPSQ has great effects on the interfacial interactions and the properties of hybrid films.With the increase of amino content,both the interracial interactions and the cross-linking density of hybrids enhanced,which results in the decline of surface silicon concentration,increase of Young's modulus and drop of elongation at break.Excessive amino content makes the hybrid films brittle and leads to incomplete imidization.

  10. Study of palladium catalyzation for electroless copper plating on polyimide film.

    Science.gov (United States)

    Kim, Bin; Jung, Sang Hee; Suh, Seung Wook; Park, Byung Ki

    2013-01-01

    In order to form flexible printed circuits through inkjet printing technique, the Pd(ll) catalyst ink was printed on the surface of polyimide film modified with KOH solution and then reduced with NaBH4 solution to extract the Pd(O) catalyst nuclei. The concentration of the Pd(ll) catalyst ink and reduction time showed a significant influence on the microstructure of the Pd(O) catalyst nuclei and the formation of Cu patterns through electroless plating. When reduction time exceeded 1 minute, and as the concentration of the Pd(II) catalyst ink increased above 0.02 M, the catalyst nuclei began aggregation, resulting in Cu patterns with thick and more defects.

  11. Electrical Bistability and Erasable Memory Effect of a Functional Polyimide Film: Synthesis and Investigation of Mechanism

    Science.gov (United States)

    Tian, Guofeng; Jia, Nanfang; Qi, Shengli; Wu, Dezhen

    2015-10-01

    A functional polyimide (PI) film, (hexafluoroisopropylidene)diphthalic anhydride-2-(9 H-carbazol-9-yl)ethyl 3,5-diaminobenzoate (6FDA-DADBC), in which DADBC serves as electron donor and 6FDA as electron acceptor, was synthesized in this work. The PI has electrical bistability and the sandwich device ITO‖6FDA-DADBC-PI‖Au made by using this functional PI as the active layer has nonvolatile memory-storage properties. It can be changed between the insulating state (Off state) and the conducting state (On state) by application of potentials of approximately 0.5 V and -2.5 V, respectively, with an On/Off current ratio of approximately 102, which is suitable for use as flash memory. Mechanisms of the charge transfer occurring in the materials were investigated, and are thoroughly discussed on the basis of molecular simulation. The PI has good thermal stability up to 400°C.

  12. PREPARATION OF POLYIMIDE-BaTiO3 HYBRID FILMS BY A DISPERSION PROCESS AND THEIR MICROSTRUCTURE

    Institute of Scientific and Technical Information of China (English)

    Yue-sheng Li; Yue-jin Tong; Kai Jing; Meng-xian Ding

    2001-01-01

    Barium titanate (BaTiO3) powders with particle sizes of 30~50 nm were prepared from barium stearate, titanium alkoxides and stearic acid by stearic acid-gel method. Dispersing the agglomerate of BaTiO3 nanoparticles into poly(amic acid) solution followed by curing led to the formation of polyimide hybrid films. The hybrid films were transparent and well distributed with BaTiO3 nanoparticles when the BaTiO3 content was less than 1 wt%. Highly loaded hybrid film containing 30 wt % BaTiO3 was tough, had a smooth surface and possessed much higher dielectric and piezoelectric constants than the parent polyimide.

  13. EFFECT OF MONTMORILLONITE ADDITION ON MECHANICAL CHARACTERIZATIONS OF POLYIMIDE NANOCOMPOSITE FILMS

    Institute of Scientific and Technical Information of China (English)

    Wang Xishu; Zhang Yihe; Fu Shaoyun; Feng Xiqiao

    2005-01-01

    Tensile deformation and fracture characteristics of polyimide/montmorillonite nanocomposite films are investigated to enhance the particular mechanical properties and understand the effective factors in dominating the mechanical properties of nanocomposites, such as the nanolayer, matrix and nanolayer/matrix interface. How to contribute to the mechanical properties of nanocomposite film is a very complex problem. In this paper, these factors are analyzed based on the addition amount and fracture mechanics. The results indicate that the specimen at 20 wt% MMT breaks prematurely with a fracture strength (σb=78 MPa) much lower than that (σb = 128 MPa) at the 1wt% MMT. However, the Young's modulus (3.2 GPa) of the former is higher than that (1.9 GPa) of the latter. Fractography also indicates that the brittle cracking formed in high content addition is the main cause of failure but microscopically ductile fracture morphology still exists locally. And for the trace element addition, the smaller threading slipping veins are evenly distributed on the entire fracture section of these films. Therefore, these characteristics would presumably be associated with both the concentration effects of size of nanocomposite sheets and the increasing deformation harmony in nanolayers.

  14. Low-temperature silicon nitride for thin-film electronics on polyimide foil substrates

    Science.gov (United States)

    Gleskova, H.; Wagner, S.; Gašparík, V.; Kováč, P.

    2001-05-01

    We optimized silicon nitride (SiN x) layers, deposited by 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) at 150°C, to provide a high quality gate dielectric layer for the amorphous silicon thin film technology on polyimide foils. The layers were deposited from mixtures of silane, ammonia, and hydrogen. We varied the H 2 flow rate from 55 to 220 sccm and the rf power from 5 to 50 W, while the pressure was kept at 500 mTorr and the ratio of ammonia to silane flow at 10:1. The best film was obtained from the gas composition of SiH 4:NH 3:H 2=1:10:44 and the rf power of ˜20 W. This film grows at the rate of 1.5 Å/s, has a refractive index n=1.80, a dielectric constant ɛ=7.46, a dielectric breakdown field >3.4 MV/cm, a Si/N ratio of ˜0.67, and a hydrogen content of ˜2×10 22 cm -3, and etches in 10:1 buffered HF at a rate of 61 Å/s.

  15. Effects of chemical etching and functionalization times on the properties of Cu/polyimide films

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Kisoo; Hwang, Soomin; Lee, Changmin; Kim, Won; Lee, Seungmuk; Park, Geunchul; Jung, Seungboo; Joo, Jinho [Sungkyunkwan University, Suwon (Korea, Republic of); Lim, Junhyung [Stanford University, Stanford, CA (United States)

    2010-12-15

    We fabricated flexible Cu/Polyimide (PI) films by electroless- and electro-Cu plating on surface modified PI via chemical etching and functionalization, and investigated the effects of the modification time on the contact angle, surface energy and morphology, Pd catalyst amount on PI, and resultant peel strength between Cu/PI layers. Chemical etching and successive functionalization were performed on PI surfaces for 0 - 10 min, followed by electroless- and electro-Cu plating. Chemical etching effectively modified the PI surface from a hydrophobic to a hydrophilic state. In addition, chemical functionalization significantly increased the amount of Pd absorption on PI, which consequently enhanced the peel strength between Cu/PI. The peel strength of the resulting Cu/PI film processed by both chemical etching and functionalization for 5 min increased to 5.08 N/cm, which was 4.2 and 2.8 times higher than films processed with functionalization and etching alone, respectively. The highest strength that was achieved was a result of the combined effects of the increased work of adhesion and the increased Pd amount for both treatments; however, the amount of Pd was likely to be the more critical factor for the high level of adhesion between Cu/PI, rather than the work of adhesion.

  16. Flexible superconducting Nb transmission lines on thin film polyimide for quantum computing applications

    Science.gov (United States)

    Tuckerman, David B.; Hamilton, Michael C.; Reilly, David J.; Bai, Rujun; Hernandez, George A.; Hornibrook, John M.; Sellers, John A.; Ellis, Charles D.

    2016-08-01

    We describe progress and initial results achieved towards the goal of developing integrated multi-conductor arrays of shielded controlled-impedance flexible superconducting transmission lines with ultra-miniature cross sections and wide bandwidths (dc to >10 GHz) over meter-scale lengths. Intended primarily for use in future scaled-up quantum computing systems, such flexible thin-film niobium/polyimide ribbon cables could provide a physically compact and ultra-low thermal conductance alternative to the rapidly increasing number of discrete coaxial cables that are currently used by quantum computing experimentalists to transmit signals between the several low-temperature stages (from ˜4 K down to ˜20 mK) of a dilution refrigerator. We have concluded that these structures are technically feasible to fabricate, and so far they have exhibited acceptable thermo-mechanical reliability. S-parameter results are presented for individual 2-metal layer Nb microstrip structures having 50 Ω characteristic impedance; lengths ranging from 50 to 550 mm were successfully fabricated. Solderable pads at the end terminations allowed testing using conventional rf connectors. Weakly coupled open-circuit microstrip resonators provided a sensitive measure of the overall transmission line loss as a function of frequency, temperature, and power. Two common microelectronic-grade polyimide dielectrics, one conventional and the other photo-definable (PI-2611 and HD-4100, respectively) were compared. Our most striking result, not previously reported to our knowledge, was that the dielectric loss tangents of both polyimides, over frequencies from 1 to 20 GHz, are remarkably low at deep cryogenic temperatures, typically 100× smaller than corresponding room temperature values. This enables fairly long-distance (meter-scale) transmission of microwave signals without excessive attenuation, and also permits usefully high rf power levels to be transmitted without creating excessive dielectric

  17. Femtosecond laser micro-machined polyimide films for cell scaffold applications.

    Science.gov (United States)

    Antanavičiūtė, Ieva; Šimatonis, Linas; Ulčinas, Orestas; Gadeikytė, Aušra; Abakevičienė, Brigita; Tamulevičius, Sigitas; Mikalayeva, Valeryia; Skeberdis, Vytenis Arvydas; Stankevičius, Edgaras; Tamulevičius, Tomas

    2016-12-11

    Engineering of sophisticated synthetic 3D scaffolds that allow controlling behavior and location of the cells requires advanced micro/nano fabrication techniques. Ultrafast laser micro-machining employing a 1030 nm wavelength Yb:KGW femtosecond laser and a micro-fabrication workstation for micro-machining of commercially available 12.7 and 25.4 µm thickness polyimide (PI) film was applied. Mechanical properties of the fabricated scaffolds, i.e., arrays of differently spaced holes, were examined via custom-built uniaxial micro-tensile testing and finite element method simulations. We demonstrate that experimental micro-tensile testing results could be numerically simulated and explained by 2-material model, assuming that 2-6 µm width rings around the holes possessed up to 5 times higher Young's modulus and yield stress compared with the rest of the laser intacted PI film areas of "dog-bone" shaped specimens. That was attributed to material modification around the micro-machined holes in the vicinity of the position of the focused laser beam track during trepanning drilling. We demonstrate that virgin PI films provide a suitable environment for the mobility, proliferation, and intercellular communication of human bone marrow mesenchymal stem cells and discuss how cell behavior varies on the micro-machined PI films with holes of different diameters (3.1, 8.4, and 16.7 µm) and hole spacing (30, 35, 40, and 45 µm). We conclude that the holes of 3.1 µm diameter were sufficient for metabolic and genetic communication through membranous tunneling tubes between cells residing on the opposite sides of PI film but prevented the trans-migration of cells through the holes. This article is protected by copyright. All rights reserved.

  18. Microscopic degradation mechanism of polyimide film caused by surface discharge under bipolar continuous square impulse voltage

    Science.gov (United States)

    Luo, Yang; Wu, Guang-Ning; Liu, Ji-Wu; Peng, Jia; Gao, Guo-Qiang; Zhu, Guang-Ya; Wang, Peng; Cao, Kai-Jiang

    2014-02-01

    Polyimide (PI) film is an important type of insulating material used in inverter-fed motors. Partial discharge (PD) under a sequence of high-frequency square impulses is one of the key factors that lead to premature failures in insulation systems of inverter-fed motors. In order to explore the damage mechanism of PI film caused by discharge, an aging system of surface discharge under bipolar continuous square impulse voltage (BCSIV) is designed based on the ASTM 2275 01 standard and the electrical aging tests of PI film samples are performed above the partial discharge inception voltage (PDIV). The chemical bonds of PI polymer chains are analyzed through Fourier transform infrared spectroscopy (FTIR) and the dielectric properties of unaged and aged PI samples are investigated by LCR testers HIOKI 3532-50. Finally, the micro-morphology and micro-structure changes of PI film samples are observed through scanning electron microscopy (SEM). The results show that the physical and chemical effects of discharge cut off the chemical bonds of PI polymer chains. The fractures of ether bond (C—O—C) and imide ring (C—N—C) on the backbone of a PI polymer chain leads to the decrease of molecular weight, which results in the degradation of PI polymers and the generation of new chemical groups and materials, like carboxylic acid, ketone, aldehydes, etc. The variation of microscopic structure of PI polymers can change the orientation ability of polarizable units when the samples are under an AC electric field, which would cause the dielectric constant ɛ to increase and dielectric loss tan δ to decrease. The SEM images show that the degradation path of PI film is initiated from the surface and then gradually extends to the interior with continuous aging. The injection charge could result in the PI macromolecular chain degradation and increase the trap density in the PI polymer bulk.

  19. The Study of Electroluminescence and Reliability of Polyimide Films in High DC Fields

    Directory of Open Access Journals (Sweden)

    Jiaqi LIN

    2015-11-01

    Full Text Available Electroluminescence (EL intensity of the polyimide (PI films was tested under dc high electric field by home-made experimental device. The results showed that the EL intensity of PI films increased along with the electric field. EL intensity is approximately to background intensity when the electric-field intensity was less than 2.00 MV/cm. EL intensity increases along with increasing the electric field when electric-field intensity greater than 2.00 MV/cm. When electric-field at 2.80 MV/cm, EL intensity increasing strongly suggests that the excitation process related to hot electrons accelerated by the field approaching a critical threshold. Meanwhile, this work elaborates a method to deal with identical samples get different experimental data by using Weibull distribution method, and the concept of the reliability was presented. The nine groups of EL experimental data were analyzed, and the result showed that the lifetime of mid-value (t = 164.9 min. Mid-value of the breakdown field is E = 2.76 MV/cm.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9694

  20. An Ensemble Learning for Predicting Breakdown Field Strength of Polyimide Nanocomposite Films

    Directory of Open Access Journals (Sweden)

    Hai Guo

    2015-01-01

    Full Text Available Using the method of Stochastic Gradient Boosting, ten SMO-SVR are constructed into a strong prediction model (SGBS model that is efficient in predicting the breakdown field strength. Adopting the method of in situ polymerization, thirty-two samples of nanocomposite films with different percentage compositions, components, and thicknesses are prepared. Then, the breakdown field strength is tested by using voltage test equipment. From the test results, the correlation coefficient (CC, the mean absolute error (MAE, the root mean squared error (RMSE, the relative absolute error (RAE, and the root relative squared error (RRSE are 0.9664, 14.2598, 19.684, 22.26%, and 25.01% with SGBS model. The result indicates that the predicted values fit well with the measured ones. Comparisons between models such as linear regression, BP, GRNN, SVR, and SMO-SVR have also been made under the same conditions. They show that CC of the SGBS model is higher than those of other models. Nevertheless, the MAE, RMSE, RAE, and RRSE of the SGBS model are lower than those of other models. This demonstrates that the SGBS model is better than other models in predicting the breakdown field strength of polyimide nanocomposite films.

  1. Programmable permanent data storage characteristics of nanoscale thin films of a thermally stable aromatic polyimide.

    Science.gov (United States)

    Kim, Dong Min; Park, Samdae; Lee, Taek Joon; Hahm, Suk Gyu; Kim, Kyungtae; Kim, Jin Chul; Kwon, Wonsang; Ree, Moonhor

    2009-10-01

    We have synthesized a new thermally and dimensionally stable polyimide, poly(4,4'-amino(4-hydroxyphenyl)diphenylene hexafluoroisopropylidenediphthalimide) (6F-HTPA PI). 6F-HTPA PI is soluble in organic solvents and is thus easily processed with conventional solution coating techniques to produce good quality nanoscale thin films. Devices fabricated with nanoscale thin PI films with thicknesses less than 77 nm exhibit excellent unipolar write-once-read-many-times (WORM) memory behavior with a high ON/OFF current ratio of up to 10(6), a long retention time and low power consumption, less than +/-3.0 V. Furthermore, these WORM characteristics were found to persist even at high temperatures up to 150 degrees C. The WORM memory behavior was found to be governed by trap-limited space-charge limited conduction and local filament formation. The conduction processes are dominated by hole injection. Thus the hydroxytriphenylamine moieties of the PI polymer might play a key role as hole trapping sites in the observed WORM memory behavior. The properties of 6F-HTPA PI make it a promising material for high-density and very stable programmable permanent data storage devices with low power consumption.

  2. Study of two different thin film coating methods in transmission laser micro-joining of thin Ti-film coated glass and polyimide for biomedical applications.

    Science.gov (United States)

    Sultana, T; Georgiev, G L; Baird, R J; Auner, G W; Newaz, G; Patwa, R; Herfurth, H J

    2009-07-01

    Biomedical devices and implants require precision joining for hermetic sealing which can be achieved with low power lasers. The effect of two different thin metal film coating methods was studied in transmission laser micro-joints of titanium-coated glass and polyimide. The coating methods were cathodic arc physical vapor deposition (CA-PVD) and electron beam evaporation (EB-PVD). Titanium-coated glass joined to polyimide film can have neural electrode application. The improvement of the joint quality will be essential for robust performance of the device. Low power fiber laser (wave length = 1100 nm) was used for transmission laser micro-joining of thin titanium (Ti) film (approximately 200 nm) coated Pyrex borosilicate 7740 glass wafer (0.5 mm thick) and polyimide (Imidex) film (0.2 mm thick). Ti film acts as the coupling agent in the joining process. The Ti film deposition rate in the CA-PVD was 5-10 A/s and in the EB-PVD 1.5 A/s. The laser joint strength was measured by a lap shear test, the Ti film surfaces were analyzed by atomic force microscopy (AFM) and the lap shear tested joints were analyzed by optical microscopy and scanning electron microscopy (SEM). The film properties and the failure modes of the joints were correlated to joint strength. The CA-PVD produced around 4 times stronger laser joints than EB-PVD. The adhesion of the Ti film on glass by CA-PVD is better than that of the EB-PVD method. This is likely to be due to a higher film deposition rate and consequently higher adhesion or sticking coefficient for the CA-PVD particles arriving on the substrate compared to that of the EB-PVD film. EB-PVD shows poor laser bonding properties due to the development of thermal hotspots which occurs from film decohesion.

  3. Peculiarities of the initial stages of carbonization processes in polyimide-based nanocomposite films containing carbon nanoparticles

    Directory of Open Access Journals (Sweden)

    I.V. Gofman

    2015-12-01

    Full Text Available Carbonization of the polyimide-based composite films containing carbon nanoparticles, namely nanofibers and nanocones/disks, in the temperature range 500–550°C was studied and the kinetics of the initial stage of carbonization and the effect of the filler on the mechanical properties of the carbonized films were evaluated. Two polyimides (PIs characterized by different macrochains’ rigidity and different degrees of ordering of the intermolecular structure were used. The character of the nanofiller’s action on the kinetics of the carbonization process depends on the heating rate. In this work, the intensity of the destruction of the PI matrix of the composite films was shown to be slightly higher than that of films of the same polymers with no filler. The introduction of the carbon nanoparticles into both PIs provokes the increase in the ultimate deformation values of the partially carbonized films, while the carbonization of the unfilled PI films yields the brittle materials. The Young’s modulus values of the materials based on the rigid-rod PI do not increase after carbonization, while those for compositions based on the PI with semi-rigid chains increase substantially. Carbon nanocones/disks are characterized by the best compatibility with matrix PIs in comparison with carbon nanofibers.

  4. Anchoring and electro-optical dynamics of thin liquid crystalline films in a polyimide cell: Experiment and theory

    Science.gov (United States)

    Lee, Lay Min; Kwon, Hye J.; Kang, Joo H.; Nuzzo, Ralph G.; Schweizer, Kenneth S.

    2006-07-01

    The surface-dependent anchoring and electro-optical (EO) dynamics of thin liquid crystalline films have been examined using Fourier transform infrared spectroscopy. A simple nematic liquid crystal, 4-n-pentyl-4'-cyanobiphenyl (5CB), is confined as 40, 50, and 390nm thick films in nanocavities defined by gold interdigitated electrode arrays (IDEAs) patterned on polyimide-coated zinc selenide (ZnSe) substrates [Noble et al., J. Am. Chem. Soc. 124, 15020 (2002)]. New strategies for controlling the anchoring interactions and EO dynamics are explored based on coating a ZnSe surface with an organic polyimide layer in order to both planarize the substrate and induce a planar alignment of the liquid crystalline film. The polyimide layer can be further treated so as to induce a strong alignment of the nematic director along a direction parallel to the electrode digits of the IDEA. Step-scan time-resolved spectroscopy measurements were made to determine the rate constants for the electric-field-induced orientation and thermal relaxation of the 5CB films. In an alternate set of experiments, uncoated ZnSe substrates were polished unidirectionally to produce a grooved surface presenting nanometer-scale corrugations. The dynamical rate constants measured for several nanoscale film thicknesses and equilibrium organizations of the director in these planar alignments show marked sensitivities. The orientation rates are found to vary strongly with both the magnitude of the applied potential and the initial anisotropy of the alignment of the director within the IDEA. The relaxation rates do not vary in this same way. The marked variations seen in EO dynamics can be accounted for by a simple coarse-grained dynamical model.

  5. Breakdown and space charge formation in polyimide film under DC high stress at various temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, Y; Hashimoto, T; Miyake, H; Tanaka, Y; Takada, T, E-mail: ytanaka@tcu.ac.j [Tokyo City University, 1-28-1, Tamatsutsumi, Setagaya-ku, Tokyo (Japan)

    2009-08-01

    Relationship between breakdown strength and space charge formation in polyimide film under dc high stress at various temperatures is investigated using pulsed electro-acoustic (PEA) method. Some typical results of the space charge observations show that hetero space charges are always found before breakdown. The amount of the hetero charges increase with increase of temperature or increase of applied electric field. Since the enhancement of the internal electric field in the sample by the accumulation of the hetero charges is not so large, the accumulation doesn't seem to be an immediate cause of breakdown. However since it is always observed before breakdown, it may be predictive information for breakdown. In a certain case, the breakdown occurs after voltage application for few hours. However, while we give an interval of short circuit condition after observing the hetero space charge under dc stress, the total voltage application time to breakdown is almost the same to the case without the interval. It means that the hetero space charge generation may show a kind of degradation of the material.

  6. Interconnection of multichannel polyimide electrodes using anisotropic conductive films (ACFs) for biomedical applications.

    Science.gov (United States)

    Baek, Dong-Hyun; Park, Ji Soo; Lee, Eun-Joong; Shin, SuJung; Moon, Jin-Hee; Pak, James Jungho; Lee, Sang-Hoon

    2011-05-01

    In this paper, we propose a method for interconnecting soft polyimide (PI) electrodes using anisotropic conductive films (ACFs). Reliable and automated bonding was achieved through development of a desktop thermocompressive bonding device that could simultaneously deliver appropriate temperatures and pressures to the interconnection area. The bonding conditions were optimized by changing the bonding temperature and bonding pressure. The electrical properties were characterized by measuring the contact resistance of the ACF bonding area, yielding a measure that was used to optimize the applied pressure and temperature. The optimal conditions consisted of applying a pressure of 4 kg f/cm(2) and a temperature of 180 °C for 20 s. Although ACF base bonding is widely used in industry (e.g., liquid crystal display manufacturing), this study constitutes the first trial of a biomedical application. We performed a preliminary in vivo biocompatibility investigation of ACF bonded area. Using the optimized temperature and pressure conditions, we interconnected a 40-channel PI multielectrode device for measuring electroencephalography (EEG) signals from the skulls of mice. The electrical properties of electrode were characterized by measuring the impedance. Finally, EEG signals were measured from the mice skulls using the fabricated devices to investigate suitability for application to biomedical devices.

  7. Influence of photoconductivity on the study of trap levels in polyimide films by photo-stimulated discharge

    Science.gov (United States)

    He, Li-Juan; Yang, Xiong; Niu, Hui-Qin; Yuan, Zhen-Hua; Li, Da-Wei; Chen, Chun-Tian

    2016-11-01

    In this paper, the distribution of the charge trap levels in polyimide (PI) films was investigated by using photo-stimulated discharge (PSD) technique, which was to explore the effect of photoconductivity on photo-stimulated discharge current. The PSD spectra show that the photo-stimulated discharge current of the PI films is mainly distributed in the range of 649-320 nm, but there are two significant current peaks when the wavelength is 300 nm and 244 nm, respectively. By studying the reason of generating two current peaks, it is concluded that the two current peaks are not generated by trapped charge de-trapping but generated by photoconductivity of charge-transfer complex in the PI films. According to the research, it is concluded that the trap levels in PI films are mainly distributed in the range of 1.92 eV-3.88 eV.

  8. Polyimides containing amide and perfluoroisopropylidene connecting groups

    Science.gov (United States)

    Dezern, James F. (Inventor)

    1993-01-01

    New, thermooxidatively stable polyimides were prepared from the reaction of aromatic dianhydrides containing isopropylidene bridging groups with aromatic diamines containing amide connecting groups between the rings. Several of these polyimides were shown to be semi-crystalline as evidenced by wide angle x ray scattering and differential scanning calorimetry. Most of the polyimides form tough, flexible films with high tensile properties. These polyimide films exhibit enhanced solubility in organic solvents.

  9. Polyimide and polyimide/silica composites membranes for applications in gas separation: effects of preparation conditions on the structure and the permeation properties; Membranes polyimide et composites polyimide/silice pour des applications de separation gazeuse: effets des conditions de preparation sur la structure et les proprietes de permeation

    Energy Technology Data Exchange (ETDEWEB)

    Goizet, S.

    1997-03-01

    Polyimides have been largely studied in gaseous permeation for their high selectivities and thermo-stability. Correlatively, their permeabilities are low. The aim of this work has been to study the effect of the introduction of silica particles on the gaseous permeation properties of these polymers. The studied polyimides are the ODA-PMDA (with the same chemical structure of the Kapton), a fluorinated polyimide, the 6FDA-mPDA and the Ultem. The chosen way to introduce silica in these polymers is the sol-gel process. Polyimide/silica composites containing different proportions of silica have been carried out. The materials alone and in presence of silica have been characterized by different techniques (NMR, FTIR, light diffusion, TGA, DSC, viscosimetry, X-ray diffraction, SEM and density). Auto-supported membranes (films) and membranes supported on porous materials (thin layers) have been carried out. The gas permeation tests (He, H{sub 2}, CO{sub 2}, O{sub 2}, N{sub 2}, CH{sub 4}) of these membranes and their static characterization (thickness, density, chains organization) have led us to establish correlations between the preparation of such materials, their structure and their properties. The introduction of silica allows to increase the permeabilities. Selectivities are in some case improved too. This phenomenon has been explained by the structural changes occurring during the preparation of materials, due to the used preparation mode and to the presence of silica. (O.M.)

  10. Precision polyimide single surface thin film shell apertures and active boundary control

    Science.gov (United States)

    Flint, Eric M.; Lindler, Jason E.; Hall, Jonathan L.; Rankine, Charles; Reggelbrugge, Mark

    2006-06-01

    This paper discusses the current status of self supporting precision membrane optical shell technology (MOST) apertures based on thin (25 to 125 um thick) polyimide and polyester films primary shell. Optically relevant doubly curved reflective apertures are realized by inducing permanent curvature into thin substrates that can then be coated. The initial thin nature provides both very low areal density (20 to 200 grams/m2) and compatibility with compact roll stowage. The induced curvature/depth provides the ability to support the shell around the periphery at discrete locations and considerable structural and dynamic stiffness. The discrete mounts also provide an excellent location with which to improve the surface figure and to reject environmental and host structure induced errors. Material microroughness on the leading substrate/coating combination has been measured to down to 3 nm rms over small (100x100um's) sample sizes with white light interferometry. A variety of reflective coated substrates have also been shown to have sub micron rms surface roughness over up to 100mm diameter test apertures using interferometric measurements. Best materials currently have 20nm rms surface roughness noise floors at these sizes. The ability to fabricate shells over a range of prescriptions (R/0.9 to R/2.2) and a range of sizes (0.1 to 0.75m diameter) has been demonstrated. Global surface figure accuracies of 2 to 4 microns rms have been demonstrated at the 0.2m size, and further improvements are anticipated through ongoing improved fabrication techniques (preliminary results indicate sub-micron rms values). The ability of discrete boundary control to improve the shape and maintain it in the face of disturbances (gravity for example) is demonstrated as is the ability to implement high amplitude (multi-wave) Zernike mode surface figure control. Results extending boundary control to interferometric optical level are also presented.

  11. Enhanced electrocatalytic oxygen evolution of α-Co(OH)2 nanosheets on carbon nanotube/polyimide films

    Science.gov (United States)

    Jiang, Yimin; Li, Xin; Wang, Tingxia; Wang, Chunming

    2016-05-01

    The future of energy supply depends on innovative breakthroughs in the development of highly efficient, sustainable and low-cost systems for renewable energy conversion and storage. Water splitting is a promising and appealing solution. In this work, we report Co(OH)2 on the carbon nanotube/polyimide film (PI/CNT-Co(OH)2) as an efficient electrocatalyst for the oxygen evolution reaction (OER). The PI/CNT film allows intimate growth of Co(OH)2 nanosheets on its surface. The nanosheet structure of Co(OH)2 and the underlying PI/CNT film facilitate the good OER performance of the PI/CNT-Co(OH)2 film. Co(OH)2 nanosheets on the PI/CNT film afford an earlier onset of oxygen evolution, a low overpotential of 317 mV and a small Tafel slope of 49 mV per decade in alkaline media. This work applies the PI/CNT film in water splitting to enhance the OER electrocatalytic activity of Co(OH)2, which opens up a promising avenue for the exploration of highly active electrocatalysts that can replace noble-metal based catalysts for the OER.The future of energy supply depends on innovative breakthroughs in the development of highly efficient, sustainable and low-cost systems for renewable energy conversion and storage. Water splitting is a promising and appealing solution. In this work, we report Co(OH)2 on the carbon nanotube/polyimide film (PI/CNT-Co(OH)2) as an efficient electrocatalyst for the oxygen evolution reaction (OER). The PI/CNT film allows intimate growth of Co(OH)2 nanosheets on its surface. The nanosheet structure of Co(OH)2 and the underlying PI/CNT film facilitate the good OER performance of the PI/CNT-Co(OH)2 film. Co(OH)2 nanosheets on the PI/CNT film afford an earlier onset of oxygen evolution, a low overpotential of 317 mV and a small Tafel slope of 49 mV per decade in alkaline media. This work applies the PI/CNT film in water splitting to enhance the OER electrocatalytic activity of Co(OH)2, which opens up a promising avenue for the exploration of highly active

  12. Preparation of Polyimide/Zinc Oxide Nanocomposite Films via an Ion-Exchange Technique and Their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Shuxiang Mu

    2011-01-01

    Full Text Available Polyimide (PI composite films with ZnO nanoparticles embedded in the surface layer were prepared by alkali hydrolyzation following ion exchange in Zn(NO32 solution and thermal treatment of the zinc ion-doped PI films in air atmosphere. The effect of alkali treatment, ion exchange, and thermal treatment conditions was investigated in relation to the amount of zinc atomic loading, morphology, photoluminescence (PL, and thermal properties of the PI/ZnO composite films using ICP, XPS, FE-SEM, TEM, Raman microscope, TGA, and DSC. ZnO nanoparticles were formed slowly and dispersed uniformly in the surface-modified layers of PI films with an average diameter of 20 nm. The PL spectra of all the PI/ZnO nanocomposite films obtained at 350°C/7 h possessed a weak ultraviolet emission peak and a broad and strong visible emission band. The PI/ZnO nanocomposite films maintained the excellent thermal property of the host PI films.

  13. Single-stage synthesis and characterization of reflective and conductive silver-polyimide films prepared from silver(I) complexes with ODPA/4,4'-ODA.

    Science.gov (United States)

    Thompson, D Scott; Davis, Luke M; Thompson, David W; Southward, Robin E

    2009-07-01

    Reflective and surface conductive polyimide films were prepared by the incorporation of silver(I) acetate and trifluoroacetylacetone into a dimethylacetamide solution of the poly(amic acid) formed 3,3',4,4'-oxidiphthalic dianhydride (ODPA) and 4,4'-oxidianiline (4,4'-ODA). Thermal curing of (trifluoroacetylacetonato)silver(I)-poly(amic acid) films led to cycloimidization with concomitant silver(I) reduction, which yielded a reflective and conductive silver surface at selected silver concentrations if the film was cured to a final temperature of 300 degrees C for several hours. The metallized ODPA/4,4'-ODA films retain the essential mechanical properties of an undoped film and have good thermal stability, particularly under a nitrogen atmosphere. The bulk of the composite film was not electrically conductive. The use of (hexafluoroacetylacetonato)silver(I) and silver(I) tetrafluoroborate as sources of silver(I) with ODPA/4,4'-ODA yielded modestly reflective films that never developed conductivity. The silvered films prepared with (trifluoroacetylacetonato)silver(I) can be patterned using mask-etch techniques. Comparisons are made among four similar silver-polyimide systems, with the polyimides being ODPA/4,4'-ODA, BTDA/4,4'-ODA, BPDA/4,4'-ODA, and 6FDA/4-BDAF.

  14. High dielectric, dynamic mechanical and thermal properties of polyimide composite film filled with carbon-coated silver nanowires

    Science.gov (United States)

    Wang, Lisi; Piao, Xiaoyu; Zou, Heng; Wang, Ya; Li, Hengfeng

    2015-01-01

    High dielectric permittivity materials are much desirable in the electric industry. Filling polymer matrix with conductive powders to form percolative composites is one of the most promising methods to achieve high dielectric permittivity. However, they do not always provide high mechanical properties and thermal stability, which seriously limit their applications. In this study, we present the preparation of functional core-shell structured silver nanowires/polyimide (AgNWs/PI) hybrid film with high dielectric permittivity and low loss dielectric. The core-shell structure of AgNWs was characterized by transmission electric microscopy. The dynamical mechanical analysis showed that AgNWs/PI hybrid films had relative high dynamic mechanical properties with storage modules over 1 Gpa. Moreover, the hybrid films exhibited excellent thermal stability with 5 % weight-loss temperature above 500 °C. The dielectric properties of the carbon-coated AgNWs hybrid films were remarkably improved. The maximum dielectric permittivity of hybrid films is 126 at 102 Hz, which was 39 times higher than that of pure PI matrix, while the dielectric loss of that is still remained at a low value. This study showed a new method to improve the dielectric, dynamic mechanical and thermal properties of films.

  15. Suppression of continuous lasing in a carbon nanotube polyimide film mode-locked erbium-doped fiber laser.

    Science.gov (United States)

    Gui, Lili; Yang, Xin; Zhao, Guangzhen; Yang, Xu; Xiao, Xiaosheng; Zhu, Jinsong; Yang, Changxi

    2011-01-01

    We demonstrated an erbium-doped mode-locked fiber laser using a single-walled carbon nanotube-dispersed polyimide (SWNT-PI) film. Different mode-locking operations were compared and analyzed utilizing SWNT-PI films with different concentrations (2, 1, and 0.25 wt.%, respectively). It was found that the continuous single-pulse mode-locking operation was often accompanied by a continuous wave oscillation part for the 1 and 0.25 wt.% SWNT-PI films, whereas the 2 wt.% SWNT-PI film presented the most excellent mode-locking performance, thanks to sufficient modulation depth. Using the 2 wt.% SWNT-PI film, a stable pulse train with a pulse width of 840 fs and a repetition rate of 15.3 MHz was achieved. The average output power was 0.33 mW at the pump power of 155 mW under an output coupling ratio of 10%. Operational performance of the laser cavity when employing the 2 wt.% SWNT-PI film was also demonstrated.

  16. Growth and Characterization of Polyimide-Supported AlN Films for Flexible Surface Acoustic Wave Devices

    Science.gov (United States)

    Li, Qi; Liu, Hongyan; Li, Gen; Zeng, Fei; Pan, Feng; Luo, Jingting; Qian, Lirong

    2016-06-01

    Highly c-axis oriented aluminum nitride (AlN) films, which can be used in flexible surface acoustic wave (SAW) devices, were successfully deposited on polyimide (PI) substrates by direct current reactive magnetron sputtering without heating. The sputtering power, film thickness, and deposition pressure were optimized. The characterization studies show that at the optimized conditions, the deposited AlN films are composed of columnar grains, which penetrate through the entire film thickness (~2 μm) and exhibit an excellent (0002) texture with a full width at half maximum value of the rocking curve equal to 2.96°. The film surface is smooth with a root mean square value of roughness of 3.79 nm. SAW prototype devices with a center frequency of about 520 MHz and a phase velocity of Rayleigh wave of about 4160 m/s were successfully fabricated using the AlN/PI composite structure. The obtained results demonstrate that the highly c-axis oriented AlN films with a smooth surface and low stress can be produced on relatively rough, flexible substrates, and this composite structure can be possibly used in flexible SAW devices.

  17. X-ray transition yields of low-Z kaonic atoms produced in Kapton

    Energy Technology Data Exchange (ETDEWEB)

    Bazzi, M. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Beer, G. [Department of Physics and Astronomy, University of Victoria, P.O. Box 1700 STN CNC, Victoria, BC V8W 2Y2 (Canada); Berucci, C. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse 3, 1090 Wien (Austria); Bombelli, L. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, Piazza L. da Vinci 32, I-20133 Milano (Italy); Bragadireanu, A.M. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); IFIN-HH, Institutul National pentru Fizica si Inginerie Nucleara Horia Hulubei, Reactorului 30, Magurele (Romania); Cargnelli, M. [Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse 3, 1090 Wien (Austria); Curceanu, C.; D' Uffizi, A. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Fiorini, C. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, Piazza L. da Vinci 32, I-20133 Milano (Italy); Ghio, F. [INFN Sezione di Roma I and Instituto Superiore di Sanita, I-00161 Roma (Italy); Guaraldo, C. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Hayano, R.S. [University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo (Japan); Iliescu, M. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Ishiwatari, T., E-mail: tomoichi.ishiwatari@assoc.oeaw.ac.at [Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse 3, 1090 Wien (Austria); Iwasaki, M. [RIKEN, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); and others

    2013-10-23

    The X-ray transition yields of kaonic atoms produced in Kapton polyimide (C{sub 22}H{sub 10}N{sub 2}O{sub 5}) were measured for the first time in the SIDDHARTA experiment. X-ray yields of the kaonic atoms with low atomic numbers (Z=6,7, and 8) and transitions with high principal quantum numbers (n=5–8) were determined. The relative yields of the successive transitions in the same atoms and the yield ratios of carbon-to-nitrogen (C:N) and carbon-to-oxygen (C:O) for the same transitions were also determined. These X-ray yields provide important information for understanding the capture ratios and cascade mechanisms of kaonic atoms produced in a compound material, such as Kapton.

  18. X-ray transition yields of low-Z kaonic atoms produced in Kapton

    CERN Document Server

    Bazzi, M; Berucci, C; Bombelli, L; Bragadireanu, A M; Cargnelli, M; Curceanu, C; d'Uffizi, A; Fiorini, C; Ghio, F; Guaraldo, C; Hayano, R S; Iliescu, M; Ishiwatari, T; Iwasaki, M; Kienle, P; Sandri, P Levi; Longoni, A; Marton, J; Okada, S; Pietreanu, D; Ponta, T; Quaglia, R; Vidal, A Romero; Sbardella, E; Scordo, A; Shi, H; Sirghi, D L; Sirghi, F; Tatsuno, H; Tudorache, A; Tudorache, V; Doce, O Vazquez; Widmann, E; Zmeskal, J

    2013-01-01

    The X-ray transition yields of kaonic atoms produced in Kapton polyimide (C22H10N2O5) were measured for the first time in the SIDDHARTA experiment. X-ray yields of the kaonic atoms with low atomic numbers (Z = 6, 7, and 8) and transitions with high principal quantum numbers (n = 5-8) were determined. The relative yield ratios of the successive transitions and those of carbon-to-nitrogen (C:N) and carbon-to-oxygen (C:O) were also determined. These X-ray yields provide important information for understanding the capture ratios and cascade mechanisms of kaonic atoms produced in a compound material, such as Kapton.

  19. 131 fs, 33 MHz all-fiber soliton laser at 1.07 microm with a film-type SWNT saturable absorber coated on polyimide.

    Science.gov (United States)

    Shohda, Fumio; Hori, Yuichiro; Nakazawa, Masataka; Mata, Junji; Tsukamoto, Jun

    2010-05-24

    We present a 1.07 microm all-fiber femtosecond soliton laser employing a film-type saturable absorber with a P3HT (poly-3-hexylthiophene) incorporated SWNT coated on polyimide film. We optimized the laser cavity as a dispersion-managed soliton laser with photonic crystal fiber (PCF) as an anomalous dispersion fiber at 1.07 microm. As a result, a 131 fs, 33 MHz pulse was successfully generated with a simple laser configuration.

  20. Lanthanide-containing polyimides

    Science.gov (United States)

    Stoakley, D. M.; St. Clair, Anne K.

    1987-01-01

    The preparation of a variety of lanthanide-containing polyimide films is described, and results of their characterization are presented. The properties investigated include the glass transition temperature, thermooxidative stability, magnetic susceptibility, and electrical conductivity of the polymer. Films containing lanthanide chlorides, fluorides, and sulfides are flexible, but those containing lanthanide nitrates are extremely brittle. The addition of lanthanide acetates and acetylacetonates caused immediate gelation of two of the synthesis-mixture ingredients. It was found that, in general, the addition of lanthanide to the polyimide increases the density and glass transition temperature of the polymer but slightly decreases the thermooxidative stability.

  1. Preparation of polyimide/Al{sub 2}O{sub 3} composite films as improved solid dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Alias, Asliza; Ahmad, Z. [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Ismail, A.B., E-mail: badri@eng.usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

    2011-06-15

    Highlights: > We prepare and characterize polyimide-alumina composite as solid dielectric. > Prolong the curing time at low temperature reduces the composite s shrinkage problem. > Dielectric constant increases with the increase of alumina content. > Thermal properties is improved with the addition of alumina. - Abstract: Considerable demand for solid thin-film dielectrics with high dielectric constants for use in the fabrication of capacitors has been observed. In this study, polyimide (PI)/Al{sub 2}O{sub 3} composite films were prepared by incorporating different micron-sized {alpha}-Al{sub 2}O{sub 3} contents into PI derived from pyromellitic dianyhydride and 4,4'-oxydianiline via ultrasonication. Chemical structure, morphology, dielectric and thermal properties were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), LCR meter and Perkin Elmer Pyris 6. FTIR spectra showed complete imidization, and all characteristic peaks of the imide groups are observed in PI and PI/Al{sub 2}O{sub 3} composite films. XRD patterns revealed that the PI/Al{sub 2}O{sub 3} composite exhibits peaks similar to those of {alpha}-Al{sub 2}O{sub 3}, indicating that the crystal structure of {alpha}-Al{sub 2}O{sub 3} remains unchanged and stable after being doped into the PI matrix. SEM micrographs showed uniform distribution of {alpha}-Al{sub 2}O{sub 3} particles in the PI matrix. Meanwhile, the dielectric constant, dielectric loss and thermal stability of PI/Al{sub 2}O{sub 3} increases with the addition of {alpha}-Al{sub 2}O{sub 3} content.

  2. Development of a Mechatronic Syringe Pump to Control Fluid Flow in a Microfluidic Device Based on Polyimide Film

    Science.gov (United States)

    Sek Tee, Kian; Sharil Saripan, Muhammad; Yap, Hiung Yin; Fhong Soon, Chin

    2017-08-01

    With the advancement in microfluidic technology, fluid flow control for syringe pump is always essential. In this paper, a mechatronic syringe pump will be developed and customized to control the fluid flow in a poly-dimethylsiloxane (PDMS) microfluidic device based on a polyimide laminating film. The syringe pump is designed to drive fluid with flow rates of 100 and 1000 μl/min which intended to drive continuous fluid in a polyimide based microfluidic device. The electronic system consists of an Arduino microcontroller board and a uni-polar stepper motor. In the system, the uni-polar stepper motor was coupled to a linear slider attached to the plunger of a syringe pump. As the motor rotates, the plunger pumps the liquid out of the syringe. The accuracy of the fluid flow rate was determined by adjusting the number of micro-step/revolution to drive the stepper motor to infuse fluid into the microfluidic device. With the precise control of the electronic system, the syringe pump could accurately inject fluid volume at 100 and 1000 μl/min into a microfluidic device.

  3. Time evolution of secondary electron emission and trapped charge accumulation in polyimide film under various primary electron irradiation currents

    Science.gov (United States)

    Song, Bai-Peng; Zhou, Run-Dong; Su, Guo-Qiang; Mu, Hai-Bao; Zhang, Guan-Jun; Bu, Ren-An

    2016-12-01

    Time-resolved evolution of secondary electron emission and trapped charge accumulation in polyimide film is investigated during two interval electrons bombardment, derived from the measurement of displacement current and secondary current via a hemispherical detector with the shielded grid. Under various irradiation current, secondary electron yield (SEY σ) at a certain injected energy decreases exponentially from initial amplitude σ0 to self-consistent steady value σ∞ close to 0.93. The time constant τ of charging process is characterized as a function of incident current Ip, and the results indicate that the formula Ip × τ is fitted by a hyperbolical law. The influence of Ip on the amount of trapped charge is studied and no significant change in its saturation value is observed. The evolution of SEY σ and trapped charge is dependent on incident dose Qp but not the incident rate Ip. Furthermore, the trap density and capture cross section are discussed.

  4. Electroless deposition of Au nanoparticles on reduced graphene oxide/polyimide film for electrochemical detection of hydroquinone and catechol

    Science.gov (United States)

    Shen, Xuan; Xia, Xiaohong; Du, Yongling; Wang, Chunming

    2017-09-01

    An electrochemical sensor for determination of hydroquinone (HQ) and catechol (CC) was developed using Au nanoparticles (AuNPs) fabricated on reduced graphene oxide/polyimide (PI/RGO) film by electroless deposition. The electrochemical behaviors of HQ and CC at PI/RGO-AuNPs electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized condition, the current responses at PI/RGO-AuNPs electrode were linear over ranges from 1 to 654 mol/L for HQ and from 2 to 1289 mol/L for CC, with the detection limits of 0.09 and 0.2 mol/L, respectively. The proposed electrode exhibited good reproducibility, stability and selectivity. In addition, the proposed electrode was successfully applied in the determination of HQ and CC in tap water and the Yellow River samples.

  5. Nanocomposites of polyimide and mixed oxide nanoparticles for high performance nanohybrid gate dielectrics in flexible thin film transistors

    Science.gov (United States)

    Kim, Ju Hyun; Hwang, Byeong-Ung; Kim, Do-Il; Kim, Jin Soo; Seol, Young Gug; Kim, Tae Woong; Lee, Nae-Eung

    2017-01-01

    Organic gate dielectrics in thin film transistors (TFTs) for flexible display have advantages of high flexibility yet have the disadvantage of low dielectric constant (low-k). To supplement low-k characteristics of organic gate dielectrics, an organic/inorganic nanocomposite insulator loaded with high-k inorganic oxide nanoparticles (NPs) has been investigated but high loading of high-k NPs in polymer matrix is essential. Herein, compositing of over-coated polyimide (PI) on self-assembled (SA) layer of mixed HfO2 and ZrO2 NPs as inorganic fillers was used to make dielectric constant higher and leakage characteristics lower. A flexible TFT with lower the threshold voltage and high current on/off ratio could be fabricated by using the hybrid gate dielectric structure of the nanocomposite with SA layer of mixed NPs on ultrathin atomic-layer deposited Al2O3.

  6. A comparative study on the mechanical and barrier characteristics of polyimide nanocomposite films filled with nanoparticles of planar and tubular morphology

    Science.gov (United States)

    Yudin, V. E.; Otaigbe, J. U.; Nazarenko, S. I.; Kim, W. D.; Korytkova, E. N.

    2011-07-01

    Polyimide (PI) films based on poly(pyromellitic dianhydride-co-4,4'-oxydianiline) (PI-PM) were filled with different nanoparticles, such as organically modified montmorillonite (MMT), vapor-grown carbon nanofibers (VGCF), and silicate nanotubes (SNT) of different concentration.. Rheological measurements and structural investigations showed a relatively good dispersion of the nanoparticles in the PI matrix to an extent that depended on the type and morphology of the nanoparticles used. The mechanical (tensile modulus, strength, and deformation at break) and the barrier (oxygen permeability) properties of PI-PM nanocomposite films were investigated. The polyimide nanocomposites filled with SNT and tubular VGCF nanoparticles showed an increased tensile modulus with increasing volume concentration of the nanoparticles without a catastrophic decrease in the elongation at break. In addition, the MMT particles, chemically modified with 4,4'-bis-(4''-aminophenoxy)diphenylsulfone, significantly improved the barrier properties of the PI-PM films, which exceeded those of the nanocomposites filled with VGCF or SNT. The relative poor oxygen barrier and mechanical properties of the PI-PM/VGCF nanocomposite films are ascribed to the relative weak adhesion between the VGCF and the polyimide matrix, which was confirmed by scanning electron microscopy of the fracture surface of these films.

  7. Direct writing of conductive silver micropatterns on flexible polyimide film by laser-induced pyrolysis of silver nanoparticle-dispersed film

    Energy Technology Data Exchange (ETDEWEB)

    Aminuzzaman, Mohammod; Watanabe, Akira, E-mail: watanabe@tagen.tohoku.ac.jp; Miyashita, Tokuji [Tohoku University, Institute of Multidisciplinary Research for Advanced Materials (IMRAM) (Japan)

    2010-03-15

    This article describes fabrication of Ag micropatterns on a flexible polyimide (PI) film by laser direct writing using an Ag nanoparticle-dispersed film as a precursor. Ag micropatterns are characterized by optical microscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), surface profilometry, and resistivity measurements. The line width of Ag micropatterns can be effectively controlled by altering the experimental parameters of laser direct writing especially laser intensity, objective lens, and laser beam scanning speed etc. Using an objective lens of 100x and laser intensity of 170.50 kW/cm{sup 2}, Ag micropatterns with a line width of about 6 {mu}m have been achieved. The Ag micropatterns show strong adhesion to polyimide surface as evaluated by Scotch-tape test. The resistivity of the Ag micropatterns is determined to be 4.1 x 10{sup -6} {Omega} cm using two-point probe method. This value is comparable with the resistivity of bulk Ag (1.6 x 10{sup -6} {Omega} cm).

  8. Superhydrophobic nanostructured Kapton® surfaces fabricated through Ar + O2 plasma treatment: Effects of different environments on wetting behaviour

    Science.gov (United States)

    Barshilia, Harish C.; Ananth, A.; Gupta, Nitant; Anandan, C.

    2013-03-01

    Kapton® [poly (4,4'-oxy diphenylene pyromellitimide)] polyimides have widespread usage in semiconductor devices, solar arrays, protective coatings and space applications, due to their excellent chemical and physical properties. In addition to their inherent properties, imparting superhydrophobicity on these surfaces will be an added advantage. Present work describes the usage of Ar + O2 plasma treatment for the preparation of superhydrophobic Kapton® surfaces. Immediately after the plasma treatment, the surfaces showed superhydrophilicity as a result of high energy dangling bonds and polar group concentration. But the samples kept in low vacuum for 48 h exhibited superhydrophobicity with high water contact angles (>150°). It is found that the post plasma treatment process, called ageing, especially in low vacuum plays an important role in delivering superhydrophobic property to Kapton®. Field emission scanning electron microscopy and atomic force microscopy were used to probe the physical changes in the surface of the Kapton®. The surfaces showed formation of nano-feathers and nano-tussock microstructures with variation in surface roughness against plasma treatment time. A thorough chemical investigation was performed using Fourier transform infrared spectroscopy and micro-Raman spectroscopy, which revealed changes in the surface of the Ar + O2 plasma treated Kapton®. Surface chemical species of Kapton® were confirmed again by X-ray photoelectron spectroscopy spectra for untreated surfaces whereas Ar + O2 plasma treated samples showed the de-bonding and re-organization of structural elements. Creation of surface roughness plays a dominant role in the contribution of superhydrophobicity to Kapton® apart from the surface modifications due to Ar + O2 plasma treatment and ageing in low vacuum.

  9. Metal-oxide assisted surface treatment of polyimide gate insulators for high-performance organic thin-film transistors.

    Science.gov (United States)

    Kim, Sohee; Ha, Taewook; Yoo, Sungmi; Ka, Jae-Won; Kim, Jinsoo; Won, Jong Chan; Choi, Dong Hoon; Jang, Kwang-Suk; Kim, Yun Ho

    2017-06-14

    We developed a facile method for treating polyimide-based organic gate insulator (OGI) surfaces with self-assembled monolayers (SAMs) by introducing metal-oxide interlayers, called the metal-oxide assisted SAM treatment (MAST). To create sites for surface modification with SAM materials on polyimide-based OGI (KPI) surfaces, the metal-oxide interlayer, here amorphous alumina (α-Al2O3), was deposited on the KPI gate insulator using spin-coating via a rapid sol-gel reaction, providing an excellent template for the formation of a high-quality SAM with phosphonic acid anchor groups. The SAM of octadecylphosphonic acid (ODPA) was successfully treated by spin-coating onto the α-Al2O3-deposited KPI film. After the surface treatment by ODPA/α-Al2O3, the surface energy of the KPI thin film was remarkably decreased and the molecular compatibility of the film with an organic semiconductor (OSC), 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10), was increased. Ph-BTBT-C10 molecules were uniformly deposited on the treated gate insulator surface and grown with high crystallinity, as confirmed by atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis. The mobility of Ph-BTBT-C10 thin-film transistors (TFTs) was approximately doubled, from 0.56 ± 0.05 cm(2) V(-1) s(-1) to 1.26 ± 0.06 cm(2) V(-1) s(-1), after the surface treatment. The surface treatment of α-Al2O3 and ODPA significantly decreased the threshold voltage from -21.2 V to -8.3 V by reducing the trap sites in the OGI and improving the interfacial properties with the OSC. We suggest that the MAST method for OGIs can be applied to various OGI materials lacking reactive sites using SAMs. It may provide a new platform for the surface treatment of OGIs, similar to that of conventional SiO2 gate insulators.

  10. Deposition of n-Type Bi2Te3 Thin Films on Polyimide by Using RF Magnetron Co-Sputtering Method.

    Science.gov (United States)

    Joo, Sung-Jae; Kim, Bong Seo; Min, Bok-Ki; Oh, Min Wook; Lee, Ji-Eun; Ryu, Byung Ki; Lee, Hee Woong; Park, Su Dong

    2015-10-01

    Bi2Te3 thermoelectric thin films were deposited on the flexible polyimide substrates by RF magnetron co-sputtering of a Bi and a Te targets. The influence of the substrate temperature and RF power on the microstructure, chemical composition, and the thermoelectric properties of the sputtered films was investigated by using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and in-plane resistivity/Seebeck coefficient measurement. It was shown that the thermoelectric properties of the films depend sensitively on the Bi/Te chemical composition ratio and the substrate temperature, and the layered structure was clearly observed from the cross section of the (00L)-oriented, nearly stoichiometric Bi2Te3 films when the substrate temperature is higher than 250 °C. As-deposited Bi2Te3 films deposited at 300 °C show the highest power factor of 0.97 mW/K(2)m and the Seebeck coefficient of -193 μV/K at 32 °C, which also have (00L) preferred orientation and the layered structure. The durability of the Bi2Te3 films on polyimide against repeated bending was also tested by monitoring the film resistance, and it was concluded that the Bi2Te3 films are applicable reliably on the curved surfaces with the radius of curvature larger than 5 mm.

  11. Atomic-Oxygen Effects on POSS Polyimides in Low Earth Orbit

    Science.gov (United States)

    2012-01-11

    Marquez, Linhan Shen, 5d. PROJECT NUMBER Amy L. Brunsvold, Russell Cooper, Jianming Zhang, Vandana Vij, Andrew J. Guenthner, Brian J. Petteys 5f...passivation layer becomes damaged. Multiple samples of Kapton H, 8.8 wt% Si8O11 MC POSS polyimide, and silica-coated Kapton HN (provided by Astral ...work was supported by the Defense Advanced Research Projects Agency (DARPA), the Air Force Office of Scientific Research (Grant Nos. F49620-01-1-0276

  12. Inlfuence of Curing Accelerators on the Imidization of Polyamic Acids and Properties of Polyimide Films

    Institute of Scientific and Technical Information of China (English)

    XU Yong; ZHAO Anlu; WANG Xinlong; XUE Hui; LIU Feilong

    2016-01-01

    In order to lower the imidization temperature of polyamic acids (PAA), the catalytic activities of the curing agents p-hydroxybenzoic acid (PHA), quinoline (QL), benzimidazole (BI), benzotriazole (BTA), triethylamine (Et3N) and 1, 8-diazabicyclo [5.4.0]undec-7-ene (DBU) were investigated in the process of thermal imidization of PAA. In addition, the effect of these various curing agents on the thermal stabilities and mechanical properties of the resultant polyimide (PI) iflms was determined. Quinoline was found to be an effective curing accelerator in the use of two-step method for synthesizing PI. Due to its moderate base strength, low steric crowding effect and moderate boiling point, quinoline could not only accelerate PAA to achieve imidization completely at 180℃, but also maintain the mechanical properties and thermal stability of the ordinary PI iflm. Any residual quinoline could be removed from PI iflms by heating at 250℃ for 4 h.

  13. Low-Toxicity PMR Polyimide

    Science.gov (United States)

    Pater, Ruth H.; Ely, Robert M.; Stanfield, Clarence E.; Dickerson, George E.; Snoha, John J.; Srinivasan, Krishna; Hou, Tan

    1994-01-01

    New low-toxicity PMR system developed and designated LaRC-RP46. Exhibits better processability, toughness, and thermo-oxidative stability than does PMR-15. Polyimide inexpensive and readily processed into high-quality graphite-fiber-reinforced composite. Used as high-performance, high-temperature-resistant adhesive, molding, composite, film, and coating material where low toxicity desired characteristic. Significantly extends applications of PMR-type polyimides.

  14. Synthesis of Aromatic Polyhedral Oligomeric Silsesquioxane (POSS) Dianilines for Use in High-Temperature Polyimides

    Science.gov (United States)

    2012-05-01

    anhydrous THF over a period of ½ h. The reaction mixture was stirred overnight followed by filtration . The filter cake was washed with distilled H2O...used in the production of Kapton-like polyimides, which were shown to exhibit excellent resistance to the atomic oxygen flux that plagues the use of...While each of these compounds has been shown to improve oxidation resistance in the host polyimide polymers, interest in materials with superior

  15. Study on preparation and dielectric properties of cellular polyimide films%聚酰亚胺多孔膜的制备与介电性能研究

    Institute of Scientific and Technical Information of China (English)

    楚晖娟; 魏宏亮; 朱宝库; 徐又一

    2011-01-01

    To explore low dielectric polyimide,cellular polyimide films were prepared from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether via a combined technique of solution induced phase separation and thermal imidization.These polyimide films displayed good thermal stability.SEM analyses showed that the obtained polyimide films had various cellular structures with the different conditions,such as the composition and temperature of coagulation bath,staying time,etc.The films with sponge-like cellular structures exhibited lower dielectric constants than those with finger-like structures.When the film was prepared in the conditions the coagulation bath of DMAc/H2O of 20/80,the temperature of 25℃ and the staying time of 20min,the film was full of sponge-like structure and its dielectric constant was low to 1.45.%以均苯四甲酸二酐和4,4′-二氨基二苯醚为原料合成聚酰亚胺前体聚酰胺酸溶液,通过溶液诱导相分离和热酰亚胺化法制备聚酰亚胺多孔膜。结果表明,用该方法得到的聚酰亚胺多孔膜具有较好的热稳定性。SEM分析显示,在不同的凝胶浴组成、凝胶浴温度和挥发时间等制膜条件下,可得到不同孔结构的多孔膜。与指状孔膜相比,海绵状孔多孔膜具有较低的介电常数。当凝胶浴组成DMAc/H2O为20/80、凝固浴温度为25℃、挥发时间为20min时,多孔膜断面几乎完全由海绵状孔组成,介电常数为1.45。

  16. Nano Particles on Aging Characteristics of Polyimide Film%纳米颗粒对聚酰亚胺膜老化特性的影响

    Institute of Scientific and Technical Information of China (English)

    曹开江; 吴广宁; 张依强; 徐慧慧; 罗杨; 王鹏

    2013-01-01

    为了研究高频方波脉冲电压下高速铁路牵引电机绝缘的老化、失效机理,给电机绝缘结构的设计和优化提供理论基础,本文研究了高频方波脉冲下牵引电机定子绝缘的老化特性.在高频方波脉冲下,对普通和纳米复合薄膜进行了老化,通过扫描电镜分析了试样表面形貌的变化情况,并对试样的剩余击穿场强进行了测试分析.研究表明:老化1小时后两种薄膜的表面形貌都发生了明显改变但变化不同,纳米粒子的添加延缓了局部放电对纳米复合薄膜的老化速率,老化2小时后普通薄膜和纳米复合薄膜的击穿场强分别下降了27.55%和12.90%.%To provide theoretical basis for design and optimization of traction motor insulation structure, an investigation of aging and failure mechanism of insulation materials under high frequency impulse voltage was carried out through inspecting aging characteristics of stator insulation under high frequency square impulse voltage. Electrical aging test was performed on the common and corona resistant polyimide (PI) films with different aging time under high frequency square impulse voltage. The dammage instance of polyimide films' surface was observed under scanning electron microscopy (SEM), and the residual insulation strength was measured and analyzed. Results show that after one hour time aging the surface morphology of the two polyimide film are changed distinctly, but the damage instances were completely different. Nano particles in the corona resistant film slow down the aging rate compared with that of common film. Residual dielectric strength of common and corona resistant polyimide films were reduced by 27. 55% and 12. 90% after two hours aging, respectively.

  17. Enhanced thermal stability of RuO2/polyimide interface for flexible device applications

    Science.gov (United States)

    Music, Denis; Schmidt, Paul; Chang, Keke

    2017-09-01

    We have studied the thermal stability of RuO2/polyimide (Kapton) interface using experimental and theoretical methods. Based on calorimetric and spectroscopic analyses, this inorganic–organic system does not exhibit any enthalpic peaks as well as all bonds in RuO2 and Kapton are preserved up to 500 °C. In addition, large-scale density functional theory based molecular dynamics, carried out in the same temperature range, validates the electronic structure and points out that numerous Ru–C and a few Ru–O covalent/ionic bonds form across the RuO2/Kapton interface. This indicates strong adhesion, but there is no evidence of Kapton degradation upon thermal excitation. Furthermore, RuO2 does not exhibit any interfacial bonds with N and H in Kapton, providing additional evidence for the thermal stability notion. It is suggested that the RuO2/Kapton interface is stable due to aromatic architecture of Kapton. This enhanced thermal stability renders Kapton an appropriate polymeric substrate for RuO2 containing systems in various applications, especially for flexible microelectronic and energy devices.

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

    Science.gov (United States)

    Wang, Junli; Qi, Shengli; Sun, Yiyi; Tian, Guofeng; Wu, Dezhen

    2016-11-01

    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 100Hz 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.

  19. Formation and Characterization of Pd, Pt and Pd-Pt Alloy Films on Polyimide by Catalyst-Enhanced Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jinlan; CHENG Yinhua; Yousuf Hamadan; YU Kaichao

    2007-01-01

    Platinum, palladium and their alloy films on polyimide were formed by catalyst-enhanced chemical vapor deposition (CVD) in the carrier gas (N2, O2) at 220-300 ℃ under reduced pressure and normal pressure. The deposition of palladium complexes [ Pd((η3-allyl)(hfac) and Pd(hfac)2 ] gives pure palladium film,while the deposition of platinum needs the enhancement of palladium complex by mixing precursor platinum complex Pt(COD)Me2 and palladium complex in the same chamber. The co-deposition of Pd and Pt metals was used for the deposition of alloy films. During the CVD of palladium-platinum alloy, the Pd/Pt atomic ratios vary under different co-deposition conditions. These metal films were characterized by XPS and SEM, and show a good adhesive property.

  20. Cryogenic microstripline-on-Kapton microwave interconnects

    CERN Document Server

    Harris, A I; Lau, J M; Church, S E; Samoska, L A; Cleary, K

    2012-01-01

    Simple broadband microwave interconnects are needed for increasing the size of focal plane heterodyne radiometer arrays. We have measured loss and cross-talk for arrays of microstrip transmission lines in flex circuit technology at 297 and 77 K, finding good performance to at least 20 GHz. The dielectric constant of Kapton substrates changes very little from 297 to 77 K, and the electrical loss drops. The small cross-sectional area of metal in a printed circuit structure yields overall thermal conductivities similar to stainless steel coaxial cable. Operationally, the main performance tradeoffs are between crosstalk and thermal conductivity. We tested a patterned ground plane to reduce heat flux.

  1. Preparation of Polyimide Porous Film with Low Dielectric Constant%低介电常数聚酰亚胺多孔薄膜的制备

    Institute of Scientific and Technical Information of China (English)

    汪英; 周福龙; 王汝柯; 李耀星

    2015-01-01

    以3,3′,4,4′-联苯四甲酸二酐和4,4′-二氨基二苯醚为单体,以三聚氰胺为成孔剂,制得一种聚酰亚胺多孔薄膜,并对薄膜的微观结构、力学性能及介电常数等进行测试。结果表明:制备该聚酰亚胺多孔薄膜的成孔工艺简单可行,三聚氰胺成孔剂可用热水溶解的方法去除。多孔薄膜孔洞数量多,且分布比较均匀。薄膜的介电常数较低、力学性能良好、吸湿率较低。当三聚氰胺添加量分别为25%和40%时,聚酰亚胺多孔薄膜的介电常数分别为1.82和1.36,聚酰亚胺多孔薄膜的拉伸强度分别为86 MPa和74 MPa,断裂伸长率分别为15%和10%。%A polyimide porous film was prepared by using 3,3’,4,4’-biphenyltetracarboxylic dianhydride and 4,4’-diaminodiphenyl ether as monomer, melamine as pore-forming agent, and its microstructure, mechanical properties, and dielectric constant were tested. The results show that the pore-forming process of the polyimide porous film is simple and feasible, and the melamine can be dissolved by hot water. The porous films have a great number of pores and their distribution is uniform. And the porous poly-imide films have low dielectric constant, good mechnical properties, and low water absorption. When the melamine addition content is 25% and 40%, the dielectric constant of the porous polyimide film is 1.82 and 1.36, the tensile strength is 86 MPa and 74 MPa, and the elongation at break is 15% and 10%, respectively.

  2. Na incorporation into Cu(In,Ga)Se2 thin-film solar cell absorbers deposited on polyimide: Impact on the chemical and electronic surface structure

    OpenAIRE

    Song, X.; Caballero, R.; Félix, R.; Gerlach, D.; Kaufmann, C.A.; H. W. Schock; Wilks, R. G.; Bär, M.

    2012-01-01

    The following article appeared in Journal of Applied Physics 111.3 (2012): 034903 and may be found at http://scitation.aip.org/content/aip/journal/jap/111/3/10.1063/1.3679604 Na has deliberately been incorporated into Cu(In,Ga)Se2 (CIGSe) chalcopyrite thin-film solar cell absorbers deposited on Mo-coated polyimide flexible substrates by adding differently thick layers of NaF in-between CIGSe absorber and Mo back contact. The impact of Na on the chemical and electronic surface structure of ...

  3. Enhanced electrical percolation due to interconnection of three-dimensional pentacene islands in thin films on low surface energy polyimide gate dielectrics.

    Science.gov (United States)

    Yang, Sang Yoon; Shin, Kwonwoo; Kim, Se Hyun; Jeon, Hayoung; Kang, Jin Ho; Yang, Hoichang; Park, Chan Eon

    2006-10-19

    The role of lateral interconnections between three-dimensional pentacene islands on low surface energy polyimide gate dielectrics was investigated by the measurement of the surface coverage dependence of the charge mobility and the use of conducting-probe atomic force microscopy (CP-AFM). From the correlation between the electrical characteristics and the morphological evolution of the three-dimensionally grown pentacene films-based field-effect transistors, we found that during film growth, the formation of interconnections between the three-dimensional pentacene islands that are isolated at the early stage contributes significantly to the enhancement process of charge mobility. The CP-AFM current mapping images of the pentacene films also indicate that the lateral interconnections play an important role in the formation of good electrical percolation pathways between the three-dimensional pentacene islands.

  4. Multilayered gold-nanoparticle/polyimide composite thin film through layer-by-layer assembly.

    Science.gov (United States)

    Zhang, Fengxiang; Srinivasan, M P

    2007-09-25

    A novel type of composite thin film consisting of gold nanoparticles (AuNPs) and polymide (PI) was fabricated through layer-by-layer (LBL) assembly. To fabricate such films, bare AuNPs and a poly (amic acid) bearing pendant amine groups, namely, amino poly (amic acid) or APAA, were synthesized and assembled in an LBL fashion. Without any organic encapsulation layer on their surface, AuNPs were bound directly to APAA chains at the amine sites; X-ray photoelectron spectroscopy study suggested that the binding was based on a combined effect of metal-ligand coordination and electrostatic interaction, with the former dominating over the latter. An approximately linear growth of the film started from the second layer of AuNP as revealed by the UV-vis spectroscopy, and the degree of particle aggregation was higher in the first AuNP layer than in the subsequent layers due to the differences in the density of binding sites. The resultant assembly was heated to imidize the APAA, thereby creating a robust composite structure.

  5. Investigation of the Structural, Electrical, and Optical Properties of the Nano-Scale GZO Thin Films on Glass and Flexible Polyimide Substrates

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2016-05-01

    Full Text Available In this study, Ga2O3-doped ZnO (GZO thin films were deposited on glass and flexible polyimide (PI substrates at room temperature (300 K, 373 K, and 473 K by the radio frequency (RF magnetron sputtering method. After finding the deposition rate, all the GZO thin films with a nano-scale thickness of about 150 ± 10 nm were controlled by the deposition time. X-ray diffraction patterns indicated that the GZO thin films were not amorphous and all exhibited the (002 peak, and field emission scanning electron microscopy showed that only nano-scale particles were observed. The dependences of the structural, electrical, and optical properties of the GZO thin films on different deposition temperatures and substrates were investigated. X-ray photoemission spectroscopy (XPS was used to measure the elemental composition at the chemical and electronic states of the GZO thin films deposited on different substrates, which could be used to clarify the mechanism of difference in electrical properties of the GZO thin films. In this study, the XPS binding energy spectra of Ga2p3/2 and Ga2p1/2 peaks, Zn2p3/2 and Zn2p1/2 peaks, the Ga3d peak, and O1s peaks for GZO thin films on glass and PI substrates were well compared.

  6. The synthesis of reflective and electrically conductive polyimide films via an in situ self-metallization procedure using silver(I) complexes

    Science.gov (United States)

    Southward, Robin Elaine

    Optically reflective polyimide films have been prepared by the incorporation of silver(I) acetate and a beta-diketone solubilizing agent, hexafluoroacetylacetone (HFAH), into a dimethylacetamide solution of the poly(amic acid) formed from 3,3sp',4,4sp'-benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4sp'-oxydianiline (4,4sp'-ODA). Optically reflective and conductive polyimide films have been prepared by replacing the beta-diketone (HFAH), with the less substituted beta-diketone, trifluoroacetylacetone (TFAH). The former system has been both cast directly from the poly(amic acid) resin and cast from the poly(amic acid) resin onto a fully imidized BTDA/4,4sp'-ODA base (forming a metallized topcoat). Thermal curing of the silver(I)-containing poly(amic acid) leads to imidization with concomitant silver(I) reduction, yielding a reflective silver surface, when HFAH is the solubilizing agent, and a reflective and surface-conductive silver surface, when TFAH is the solubilizing agent. The metallized BTDA/4,4sp'-ODA films retain the essential mechanical properties of undoped films and have good thermal stability particularly in nitrogen atmospheres. The system which forms a metallized topcoat also exhibits the essential mechanical and thermal properties of the parent polymer while minimizing the silver required to form the reflective surface, and has outstanding metal-polymer and polymer-polymer adhesion attributed to mechanical interlocking. Films were characterized by X-ray, DSC, TGA, XPS, TEM, SEM, AFM.

  7. Polyimide/nanosized CaCu3Ti4O12 functional hybrid films with high dielectric permittivity

    Science.gov (United States)

    Yang, Yang; Zhu, Ben-Peng; Lu, Zhi-Hong; Wang, Zi-Yu; Fei, Chun-Long; Yin, Di; Xiong, Rui; Shi, Jing; Chi, Qing-Guo; Lei, Qing-Quan

    2013-01-01

    This work reports the high dielectric permittivity of polyimide (PI) embedded with CaCu3Ti4O12 (CCTO) nanoparticles. The dielectric behavior has been investigated over a frequency of 100 Hz-1 MHz. High dielectric permittivity (ɛ = 171) and low dielectric loss (tan δ = 0.45) at 100 Hz have been observed near the percolation threshold. The experimental results fit well with the Percolation theory. We suggest that the high dielectric permittivity originates from the large interface area and the remarkable Maxwell-Wagner-Sillars effect at percolation in which nomadic charge carriers are blocked at internal interfaces between CCTO nanoparticles and the polyimide matrix.

  8. Solution-processed and low-temperature metal oxide n-channel thin-film transistors and low-voltage complementary circuitry on large-area flexible polyimide foil

    NARCIS (Netherlands)

    Rockelé, M.; Pham, D.V.; Steiger, J.; Botnaras, S.; Weber, D.; Vanfleteren, J.; Sterken, T.; Cuypers, D.; Steudel, S.; Myny, K.; Schols, S.; Putten, J.B.P.H. van der; Genoe, J.; Heremans, P.

    2012-01-01

    High-performance solution-based n-type metal oxide thin-film transistors (TFTs), fabricated directly on polyimide foil at a post-annealing temperature of only 250''C, are realized and reported. Saturation mobilities exceeding 2cmV(Vs) and on-to-off current ratios up to 10^ are achieved. The usage of

  9. Large-area Kapton x-ray windows

    Science.gov (United States)

    Antimonov, M.; Khounsary, A.; Weigand, S.; Rix, J.; Keane, D.; Grudzinski, J. J.; Johnson, A.; Zhou, Z.; Jansma, W.

    2015-09-01

    Some X-ray instruments require the utilization of large-area windows to provide vacuum barriers. The necessary attributes of the window material include transparency to X-rays, low scattering, and possession of suitable mechanical properties for reliable long-term performance. Kapton is one such material except that it is a polymer and a large window made from Kapton with a pressure differential of one atmosphere across it can undergo substantial deformation at room temperature. In this paper, we report on the mechanical testing of Kapton samples including creep measurements, and comparison with published data. We use of these data together with analytical / numerical models to predict the changes in the profile of Kapton vacuum windows over time, and show good agreement with experimental measurements.

  10. Using Flexible Polyimide as a Substrate to Deposit ZnO:Ga Thin Films and Fabricate p-i-n α-Si:H Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2013-01-01

    Full Text Available The GZO thin films were deposited on the polyimide (PI substrates to investigate their properties for the possibly flexible applications. The effects of substrate temperature (from room temperature to 200°C on the surface and cross-session morphologies, X-ray diffraction pattern, optical transmission spectrum, carrier concentration, carrier mobility, and resistivity of the GZO thin films on PI substrates were studied. The measured results showed that the substrate temperature had large effect on the characteristics of the GZO thin films. The cross-section observations really indicated that the GZO thin films deposited at 200°C and below had different crystalline structures. The value variations in the films’ optical band gap (Eg of the GZO thin films were evaluated from plots of  (αhν2=c(hν-Eg, revealing that the measured Eg values increased with increasing deposition temperature. Finally, the prepared GZO thin films were also used as the transparent electrodes to fabricate the α-Si amorphous silicon thin-film solar cells on the flexible PI substrates, and the properties of which were also measured. We would also prove that substrate temperature of the GZO thin films had large effect on the characteristics of the fabricated α-Si amorphous silicon thin-film solar cells.

  11. Single crystalline growth of a soluble organic semiconductor in a parallel aligned liquid crystal solvent using rubbing-treated polyimide films

    Science.gov (United States)

    Matsuzaki, Tomoya; Shibata, Yosei; Takeda, Risa; Ishinabe, Takahiro; Fujikake, Hideo

    2017-01-01

    For directional control of organic single crystals, we propose a crystal growth method using liquid crystal as the solvent. In this study, we examined the formation of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) single crystals using a parallel aligned liquid crystal (LC) cell and rubbing-treated polyimide films in order to clarify the effects of LC alignment on anisotropic C8-BTBT crystal growth. Based on the results, we found that the crystal growth direction of C8-BTBT single crystals was related to the direction of the aligned LC molecules because of rubbing treatment. Moreover, by optical evaluation, we found that the C8-BTBT single crystals have a aligned molecular structure.

  12. Flexible Cu(In,Ga)Se2 Thin-Film Solar Cells on Polyimide Substrate by Low-Temperature Deposition Process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; HE Qing; JIANG Wei-Long; LI Chang-Jian; SUN Yun

    2008-01-01

    The electrical and structural properties of polycrystalline Cu(In,Ga)Se2 films grown on polyimide (PI) substrates below 400℃ via one-stage and three-stage co-evaporation process have been investigated by x-ray diffraction spectra (XRD),scanning electron microscopy (SEM) and Hall effect measurement.As shown by XRD spectra,the stoichiometric CIGS films obtained by one-stage process exhibit the characteristic diffraction peaks of the (In0.68Ga0.32)2Se3 and Cu(In0.7Ga0.3)2Se.It is also found that the film structures indicate more columnar and compact than the three-stage process films from SEM images.The stoichiometric CIGS films obtained by three-stage process exhibit the coexistence of the secondary phase of (In0.68Ga0.32)2Se3,Cu2-xSe and Cu(In0.7Ga0.3)2Se.High net carrier concentration and sheet conductivity are also observed for this kind of film,related to the presence of Cu2-xSe phase.As a result,when the CIGS film growth temperature is below 400℃,the three-stage process is inefficient for solar cells.By using the one-stage co-evaporation process,the flexible CIGS solar cell on a PI substrate with the best conversion efficiency of 6.38% is demonstrated (active area 0.16cm2).

  13. Effect of using polyimide capillaries during thermal experiments on the particle size distribution of supported Pt nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gámez-Mendoza, Liliana; Resto, Oscar; Martínez-Iñesta, María

    2015-09-20

    Kapton HN-type polyimide capillaries are commonly used as sample holders for transmission X-ray experiments at temperatures below 673 K because of their thermal stability, high X-ray transmittance and low cost. Using high-angle annular dark field scanning high-resolution transmission electron microscopy and thermogravimetric analysis, this work shows that using polyimide capillaries leads to the overgrowth of supported Pt nanoparticles during reduction at temperatures below the glass transition temperature (Tg= 658 K) owing to an outgassing of water from the polyimide. Quartz capillaries were also studied and this overgrowth was not observed.

  14. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties

    Science.gov (United States)

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-06-01

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (108). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system

  15. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties.

    Science.gov (United States)

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-07-07

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (10(8)). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.

  16. Research Update: Polyimide/CaCu3Ti4O12 nanofiber functional hybrid films with improved dielectric properties

    Science.gov (United States)

    Yang, Yang; Wang, Ziyu; Ding, Yi; Lu, Zhihong; Sun, Haoliang; Li, Ya; Wei, Jianhong; Xiong, Rui; Shi, Jing; Liu, Zhengyou; Lei, Qingquan

    2013-11-01

    This work reports the excellent dielectric properties of polyimide (PI) embedded with CaCu3Ti4O12 (CCTO) nanofibers. The dielectric behaviors were investigated over a frequency of 100 Hz-1 MHz. It is shown that embedding CCTO nanofibers with high aspect ratio (67) is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric permittivity of PI/CCTO nanofiber composites is 85 with 1.5 vol.% loading of filler, also the dielectric loss is only 0.015 at 100 Hz. Monte Carlo simulation was used to investigate the percolation threshold of CCTO nanofibers reinforced polyimide matrix by using excluded volume theory and soft, hard-core models. The results are in good agreement with the percolation theory and the hard-core model can well explain the percolation phenomena in PI/CCTO nanofiber composites. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  17. Research Update: Polyimide/CaCu3Ti4O12 nanofiber functional hybrid films with improved dielectric properties

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2013-11-01

    Full Text Available This work reports the excellent dielectric properties of polyimide (PI embedded with CaCu3Ti4O12 (CCTO nanofibers. The dielectric behaviors were investigated over a frequency of 100 Hz–1 MHz. It is shown that embedding CCTO nanofibers with high aspect ratio (67 is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric permittivity of PI/CCTO nanofiber composites is 85 with 1.5 vol.% loading of filler, also the dielectric loss is only 0.015 at 100 Hz. Monte Carlo simulation was used to investigate the percolation threshold of CCTO nanofibers reinforced polyimide matrix by using excluded volume theory and soft, hard-core models. The results are in good agreement with the percolation theory and the hard-core model can well explain the percolation phenomena in PI/CCTO nanofiber composites. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  18. Study on performances of colorless and transparent shape memory polyimide film in space thermal cycling, atomic oxygen and ultraviolet irradiation environments

    Science.gov (United States)

    Gao, Hui; Lan, Xin; Liu, Liwu; Xiao, Xinli; Liu, Yanju; Leng, Jinsong

    2017-09-01

    Shape memory polymers with high glass transition temperature (HSMPs) and HSMP-based deployable structures and devices, which can bear harsh operation conditions for durable applications, have attracted more and more interest in recent years. In this article, colorless and transparent shape memory polyimide (SMCTPI) films were subjected to simulated vacuum thermal cycling, atomic oxygen (AO) and ultraviolet (UV) irradiation environments up to 600 h, 556 h and 600 h for accelerated irradiation. The glass transition temperature (T g) determined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) had no obvious changes after being irradiated by varying amounts of thermal cycling, AO and UV irradiation dose. After being irradiated by 50 thermal cycles, 10 × 1021 atoms cm-2 AO irradiation and 3000 ESH UV irradiation, shape recovery behaviors of SMCTPI films also had no obvious damage even if they experienced 30 shape memory cycles, while the surface morphologies and optical properties were seriously destroyed by AO irradiation, as compared with thermal cycling and UV irradiation. The tensile strength could separately maintain 122 MPa, 120 MPa and 70 MPa after 50 thermal cycles, 10 × 1021 atoms cm-2 AO irradiation and 3000 ESH UV irradiation, which shows great potential for use in aerospace structures and devices.

  19. Spectroscopic comparison of effects of electron radiation on mechanical properties of two polyimides

    Science.gov (United States)

    Long, Edward R., Jr.; Long, Sheila Ann T.

    1987-01-01

    The differences in the radiation durabilities of two polyimide materials, Du Pont Kapton and General Electric Ultem, are compared. An explanation of the basic mechanisms which occur during exposure to electron radiation from analyses of infrared (IR) and electron paramagnetic resonance (EPR) spectroscopic data for each material is provided. The molecular model for Kapton was, in part, established from earlier modeling for Ultem (pp. 1293-1298 of IEEE Transactions on Nuclear Science, December 1984). Techniques for understanding the durability of one complex polymer based on the understanding of a different and equally complex polymer are demonstrated. The spectroscopic data showed that the primary radiation-generated change in the tensile properties of Ultem (a large reduction in tensile elongation) was due to crosslinking, which followed the capture by phenyl radicals of hydrogen atoms removed from gem-dimethyl groups. In contrast, the tensile properties of Kapton remained unchanged because radical-radical recombination, a self-mending process, took place.

  20. Room-temperature preparation and dielectric properties of amorphous Bi3.95Er0.05Ti3O12 thin films on flexible polyimide substrates via pulsed laser deposition method

    Science.gov (United States)

    Mo, Zhong; Wu, Guangheng; Bao, Dinghua

    2012-05-01

    Bi3.95Er0.05Ti3O12 (BErT) thin films were prepared on flexible polyimide (PI) substrates at room temperature by pulsed laser deposition. These BErT thin films deposited under low oxygen pressures are dense, uniform, and crack-free with an amorphous structure. The highly flexible thin film with a thickness of about 160 nm deposited under 3 Pa oxygen pressure shows excellent dielectric characteristics, such as a dielectric constant of 51 and a dielectric loss of 0.025, and a maximum capacitance density of 237 nF/cm2 at 1 kHz. When it is curved at different curvature radii (by applying external deformation), the thin film still remains superior dielectric performance. In addition, the thin film also shows good dielectric aging characteristic (or thermal stability) and high optical transparency. BErT thin films can find applications in flexible optoelectronic devices and embedded capacitors.

  1. Polyimides Containing Amide And Perfluoroisopropyl Links

    Science.gov (United States)

    Dezem, James F.

    1993-01-01

    New polyimides synthesized from reactions of aromatic hexafluoroisopropyl dianhydrides with asymmetric amide diamines. Soluble to extent of at least 10 percent by weight at temperature of about 25 degrees C in common amide solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide. Polyimides form tough, flexible films, coatings, and moldings. Glass-transition temperatures ranged from 300 to 365 degrees C, and crystalline melting temperatures observed between 543 and 603 degrees C. Display excellent physical, chemical, and electrical properties. Useful as adhesives, laminating resins, fibers, coatings for electrical and decorative purposes, films, wire enamels, and molding compounds.

  2. SYNTHESIS AND ELECTRICAL PROPERTIES OF POLYIMIDE-Al2O3 COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Hong-yan Li; Shu-fan Ning; Hai-bing Hu; Bin Liu; Wei Chen; Shou-tian Chen

    2007-01-01

    Polyimide-alumina hybrid films were synthesized via in situ polymerization and thermal imidation process from a solution of polyimide precursor and nanosized alumina in N,N-dimethylacetamide, and the microstructure of the hybrid films was characterized by transmission electron microscope (TEM) and infra-red (IR) spectrometry. The dependence of thermal stability, tensile properties, dielectric properties and degradation endurance under corona on the nano-Al2O3 content of polyimide-alumina hybrid films was studied. The results show that with the increase of Al2O3 content, the thermal stability and the dielectric properties of the hybrids increase, while the tensile properties decrease. Better corona resistance can be achieved if the PI film is filled with α-Al2O3 nanometric particle.

  3. A Compact Kapton-based Inkjet Printed Multiband Antenna for Flexible Wireless Devices

    KAUST Repository

    Ahmed, Sana

    2015-04-20

    A low cost inkjet printed multiband antenna envisioned for integration into flexible and conformal mobile devices is presented. The antenna structure contains a novel triangular iterative design with coplanar waveguide (CPW) feed, printed on a Kapton polyimide-based flexible substrate with dimensions of 70 x 70 x 0.11 mm3. The antenna covers four wide frequency bands with measured impedance bandwidths of 54.4%, 14%, 23.5% and 17.2%, centered at 1.2, 2.0, 2.6 and 3.4 GHz, respectively, thus, enabling it to cover GSM 900, GPS, UMTS, WLAN, ISM, Bluetooth, LTE 2300/ 2500 and WiMAX standards. The antenna has omnidirectional radiation pattern with a maximum gain of 2.1 dBi. To characterize the flexibility of the antenna, the fabricated prototype is tested in convex and concave bent configurations for radii of 78mm and 59mm. The overall performance remains unaffected, except a minor shift of 20 MHz and 60 MHz in S11, for concave bending at both radii. The compact, lightweight and conformal design as well as multiband performance in bent configurations, proves the suitability of the antenna for future electronic devices.

  4. Na incorporation into Cu(In,Ga)Se2 thin-film solar cell absorbers deposited on polyimide: Impact on the chemical and electronic surface structure

    Science.gov (United States)

    Song, X.; Caballero, R.; Félix, R.; Gerlach, D.; Kaufmann, C. A.; Schock, H.-W.; Wilks, R. G.; Bär, M.

    2012-02-01

    Na has deliberately been incorporated into Cu(In,Ga)Se2 ("CIGSe") chalcopyrite thin-film solar cell absorbers deposited on Mo-coated polyimide flexible substrates by adding differently thick layers of NaF in-between CIGSe absorber and Mo back contact. The impact of Na on the chemical and electronic surface structure of CIGSe absorbers with various Cu-contents deposited at comparatively low temperature (420 °C) has been studied using x-ray photoelectron and x-ray excited Auger electron spectroscopy. We observe a higher Na surface content for the Cu-richer CIGSe samples and can distinguish between two different chemical Na environments, best described as selenide-like and oxidized Na species, respectively. Furthermore, we find a Cu-poor surface composition of the CIGSe samples independent of Na content and — for very high Na contents — indications for the formation of a (Cu,Na)-(In,Ga)-Se like compound. With increasing Na surface content, also a shift of the photoemission lines to lower binding energies could be identified, which we interpret as a reduction of the downward band bending toward the CIGSe surface explained by the Na-induced elimination of InCu defects.

  5. Localized Etching of a Polyimide Film by an Atmospheric-Pressure Radio Frequency Microplasma Excited by a 100-µm-φ Metal Pipe Electrode

    Science.gov (United States)

    Yoshiki, Hiroyuki

    2010-08-01

    Atmospheric-pressure He and Ar microplasmas (µ-plasmas) have been generated by a 14 MHz radio-frequency (RF) discharge using a metal narrow pipe electrode with an outer diameter of 100 µm. The metal pipe acts as both a powered electrode and a gas nozzle. The discharge mode changed from a corona discharge to a glow discharge and finally to a thermal spot arc discharge with decreasing discharge gap between the pipe electrode and the grounded plate as well as with increasing RF power. The Ar glow µ-plasma was applied to the localized etching of a polyimide film with a thickness of 0.025 mm in air ambient. The etched spot showed an isotropic profile having a gradual slope with a full width at half maximum of approximately 170 µm. The etching rate was approximately 3 µm/s at an RF power of 1.5 W. The optical emission spectrum exhibited second-positive N2 molecular bands and atomic oxygen lines (777 and 845 nm) as well as many Ar atomic lines. It appears that the energetic N2 molecules and UV photons radiated from the excitation states of N2 broke C-C and C-H bonds and then O radicals reacted with the hydrocarbon fragments to produce CO2 and H2O. Consequently, isotropic chemical etching was achieved.

  6. Preparation and Properties of Polyimide Film with Carboxyl Group%含羧基聚酰亚胺薄膜的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    虞鑫海; 许梅芳; 祖热古丽·买买提; 徐永芬

    2011-01-01

    Using 3, 5-diaminobenzoic acid(35DABA), 4,4'-diaminodipehenyl ether(44ODA) and 3,3',4, 4'-tetracarboxylbiphenyl dianhydride(BPDA) as raw materials, a highly viscous polyamide acid with carboxyl group(CPAA) solution was prepared in aprotic organic solvents. A tensile and transparent polyimide film with carboxyl group(CPI) was prepared by thermal imidization of CPAA thin layer, and the properties of the film were studied. The results show that the CPI film has high surface energy and good stability under high and low frequency; the capacitance value and dielectric loss do not change in a broad range of frequency. With high strength and good toughness, the film can be used to prepare high performance flexible copper clad laminate. The film also has good absorptive capacity in the short wavelength region of ultraviolet; its cutoff wavelength is 320 nm. The transmittance attains more than 80% in the visible light region.%以3,5-二氨基苯甲酸(35DABA)、4,4’-二氨基二苯醚(44ODA)和3,3’,4,4’-四甲酸联苯二酐(BPDA)为原料,在强极性非质子有机溶剂中进行聚合反应,制得了高粘度含羧基聚酰胺酸(CPAA)溶液,经涂膜、热亚胺化,得到了坚韧透明的含羧基聚酰亚胺(CPI)薄膜,并对其性能进行了研究.结果表明:CPI薄膜具有较高的表面能,在宽广的频率范围内,其电容、介质损耗基本保持不变,具有良好的高低频稳定性;薄膜的强度与韧性均较高,可应用于制作高性能柔性覆铜板;薄膜在紫外线短波长区具有良好的吸收能力,其截止波长为320 nm,在可见光波长范围内,其透过率达80%以上.

  7. Area-selective atomic layer deposition of platinum using photosensitive polyimide

    Science.gov (United States)

    Vervuurt, René H. J.; Sharma, Akhil; Jiao, Yuqing; Kessels, Wilhelmus (Erwin M. M.; Bol, Ageeth A.

    2016-10-01

    Area-selective atomic layer deposition (AS-ALD) of platinum (Pt) was studied using photosensitive polyimide as a masking layer. The polyimide films were prepared by spin-coating and patterned using photolithography. AS-ALD of Pt using poly(methyl-methacrylate) (PMMA) masking layers was used as a reference. The results show that polyimide has excellent selectivity towards the Pt deposition, after 1000 ALD cycles less than a monolayer of Pt is deposited on the polyimide surface. The polyimide film could easily be removed after ALD using a hydrogen plasma, due to a combination of weakening of the polyimide resist during Pt ALD and the catalytic activity of Pt traces on the polyimide surface. Compared to PMMA for AS-ALD of Pt, polyimide has better temperature stability. This resulted in an improved uniformity of the Pt deposits and superior definition of the Pt patterns. In addition, due to the absence of reflow contamination using polyimide the nucleation phase during Pt ALD is drastically shortened. Pt patterns down to 3.5 μm were created with polyimide, a factor of ten smaller than what is possible using PMMA, at the typical Pt ALD processing temperature of 300 °C. Initial experiments indicate that after further optimization of the polyimide process Pt features down to 100 nm should be possible, which makes AS-ALD of Pt using photosensitive polyimide a promising candidate for patterning at the nanoscale.

  8. Thermal bonding of polyimide to form sealed microchannels

    Science.gov (United States)

    Mekaru, Harutaka

    2017-06-01

    Polyimide has high stability, so it is attractive for use in disposable microfluidic chips. Also, it has high resistance to soft X-ray irradiation. However, its high stability makes processing polyimide difficult. In particular, sealed microchannels are difficult to fabricate; additives are usually required. Here, a technique for sealing microchannels by thermal bonding using ordinary polyimide without any special functionalities is developed. First, as a guide to form sealed microchannels in polyimide microfluidic chips, optimum bonding conditions are determined by measuring bonding strength through tensile testing. Trench structures are formed by laser ablation on the surface of a polyimide substrate, and then the polyimide substrate is bonded thermally with a polyimide film under optimal bonding conditions. The water-tightness of the resulting chip is checked by feeding a liquid into the sealed microchannels. The bonding conditions obtained in the tensile test form sealed microchannels on the polyimide microfluidic chip. Using our technique for fabricating a polyimide chip, it will be possible to easily observe microstructures in a cell containing water in a soft X-ray microscope.

  9. 基于介电谱分析聚酰亚胺薄膜的老化特征%Aging Characteristics of Polyimide Film Based on Dielectric Spectra

    Institute of Scientific and Technical Information of China (English)

    高波; 吴广宁; 曹开江; 罗杨; 王鹏; 崔易

    2011-01-01

    The accelerated aging test of common and nano polyimide film was conducted under bipolar impulses voltage. The dielectric frequency spectra and temperature spectra of the film be fore and after aging were analyzed. The relationships between microscopic molecular structure and macroscopic dielectric property were studied by SEM. The results show that the dipole relaxation loss peak in high frequency region moves towards higher frequency and the loss peak originated from interface polarization in low temperature region towards higher temperature after aging. And the aging breaks down the molecular chain of the film and generates polar molecules with small molecular weight, making the orientation polarization be built more easily. The addition of nanometer reduces the destroying effect of aging factor on the internal structure of the film, thus greatly decreasing the relaxation loss originated from dipole orientation polarization. A great deal of interface defects are formed from nano-doping which greatly increase the dielectric loss origi nated from interface polarization.%对纳米和普通聚酰亚胺薄膜进行了双极性脉冲电压下的老化试验,分析了薄膜老化前后的介电频率谱和温度谱,并借助电镜扫描分析,研究了薄膜老化前后的微观结构形态与宏观介电性能之间的关系.结果表明:老化使聚酰亚胺薄膜介电频率谱中的偶极子弛豫损耗峰向高频移动,低温区的界面极化损耗峰向高温移动;且老化使聚酰亚胺薄膜分子链断裂,生成分子量小的极性分子,使取向极化更易建立;纳米粒子的加入,削弱了老化因子对聚酰亚胺薄膜内部结构的破坏作用,使偶极子取向带来的弛豫损耗大大减小;纳米掺杂形成大量的界面缺陷,使界面极化带来的介质损耗大大增加.

  10. Nonadhesive acoustic membranes based on polyimide

    Directory of Open Access Journals (Sweden)

    Vorob'ev A.V.

    2014-02-01

    Full Text Available The paper presents a comparison of technical characteristics of acoustic membranes with an adhesive layer and nonadhesive membranes. The authors present the manufacturing technology for acoustic membranes based on aluminum-polyimide film dielectrics and analyze the advantages of such membranes in comparison to other sound emitters.

  11. Polyimides with pendent ethynyl groups

    Science.gov (United States)

    Jensen, Brian J.; Hergenrother, Paul M.; Nwokogu, Godson

    1992-01-01

    Several new polyimides containing pendent ethynyl groups were prepared and characterized. The new polyimides were prepared from the following novel ethynyl containing diamines; 1,1-bis(p aminophenyl)-1-(p ethynylphenyl) 2,2,2-trifluoroethane, and 1,1-bis(p aminophenyl)-1-(p phenylethynylphenyl)-2,2,2 trifluoroethane, and 1,1-bis(p aminophenyl)-1-(p hexynylphenyl)-2,2,2 trifluoroethane by reacting with either 3,3',4,4' benzophenone tetracarboxylic dianhydride or 2,2-bis(3,4 dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). Inherent viscosities for the polymers ranged from 0.26 to 0.94 dL/g. Three copolymers prepared by reacting 10 mole pct. of one of the ethynyl containing diamines and 90 mole pct. of 2,2-bis-(4-(4 aminophenoxy)phenyl) hexafluoropropane with 6FDA were also prepared and characterized. Inherent viscosities for these copolymers ranged from 1.08 to 1.54 dL/g. Original polyimide glass transition temperatures were approx. 265 C while curing at 300 to 350 C for 1 hr in air increased the Tgs by approx. 10 C. Film properties and thermal stability were also measured for these copolyimides.

  12. Fabrication of Pentacene Thin-Film Transistors with Patterned Polyimide Photoresist as Gate Dielectrics and Research of Their Degradation

    Institute of Scientific and Technical Information of China (English)

    LIANG Yan; DONG Gui-Fang; HU Yuan-Chuan; HU Yan; WANG Li-Duo; QIU Yong

    2004-01-01

    @@ Pentacene organic thin-film transistors using commercial photoresist as gate dielectrics were fabricated. The photoresist was spin-coated and directly patterned by photolithography. As a result, the fabrication processes were greatly reduced. With the characteristics of the transistors measured, the degradation of the transistors was investigated. In the search for the factors causing degradation, a transistor using poly(methyl methacrylate)as the gate dielectric was also fabricated. It is regarded that the degradation is caused by the changes at the interface between photoresist and pentacene film.

  13. Study of Kapton insulated superconducting coils manufactured for the LHC inner triplet model magnets at Fermilab

    CERN Document Server

    Andreev, N; Bossert, R; Brandt, J; Chichili, D R; Kerby, J S; Nobrega, A; Novitski, I; Ozelis, J P; Yadav, S; Zlobin, A V

    2000-01-01

    Fermilab has constructed a number of 2 m model quadrupoles as part of an ongoing program to develop and optimize the design of quadrupoles for the LHC Interaction Region inner triplets. The quadrupole design is based upon a two layer shell type coil of multi-filament NbTi strands in Rutherford cable, insulated with Kapton film. As such, the coil size and mechanical properties are critical in achieving the desired prestress and field quality targets for the agent. Throughout the model magnet program, different design and manufacturing techniques have been studied to obtain coils with the required mechanical properties. This paper summarizes the structural material and coil mechanical properties, coil design optimization results and production experience accumulated in the model R&D program. (5 refs).

  14. Integrated real time studies to track all physical and chemical changes in polyimide film processing from casting to imidization

    Science.gov (United States)

    Unsal, Emre

    Physical and chemical changes during the complex multi-step thermal imidization reaction were investigated including all processing steps (solution casting, drying and imidization), using newly developed highly instrumented measurement systems. These instruments allowed us to observe the dynamic relationship between the bound solvent evaporation that causes relaxation and chain orientation during the imidization. Drying and imidization of PMDA-ODA solutions in NMP were investigated by a novel custom designed measurement system that tracks real time weight, thickness, surface temperature, in-plane and out-of-plane birefringence. At low temperature drying stage (T bound solvent as solvent molecules decomplexed from the polymer chains and plasticized the film. During the latter stage, out-of-plane birefringence rose rapidly as the polymer chains increasingly became oriented with their chain axes were preferentially oriented in the film plane. Throughout the whole process the in-plane birefringence remained zero. For the first time, these real time measurements allowed us to quantitatively show the dynamics between chain relaxation due to evaporation of the decomplexed solvent molecules, and orientation development due to decreased chain mobility caused by imidization reaction and increasing Tg for the PMDA-ODA/NMP solutions. In addition, the dynamics of this interplay was investigated by varying the processing conditions: initial casting thickness and drying temperature. Chemical conversion, bound solvent and chain orientation that take place during thermal imidization of uniaxially constraint PMDA-ODA polyamic acid precursor film was investigated up to 200°C using real time measurement system that combines true stress, true strain, in-plane birefringence and temperature with polarized ultra-rapid scan polarized FT-IR spectrometry (URS-FT-IR). Upon heating, initially isotropic solution cast film developed stress and birefringence from the beginning while the solvent

  15. Synthesis of novel aromatic polyimides containing bulky side chain for vertical alignment liquid crystals

    Institute of Scientific and Technical Information of China (English)

    Jian Wang; Ying Han Wang

    2008-01-01

    In this study, a novel 4-(4-octyloxybenzoyloxy)biphenyl-3',5'-diaminobenzoate and polyimides based on it were synthesized. The polyimide with mesogenic unit side chain exhibited excellent vertical alignment for nematic liquid crystal (LC). The pretilt angles of LCs above 89° were kept after the rubbing process with 220 mm rubbing strength. The polyimide films as the alignment layer were baked at 120℃ for 12 h, the vertical alignment of LCs was still uniform and stable. Meanwhile, the UV-vis spectra of the novel polyimide films showed the high transparency in a visible wave length.

  16. 3F Condensation Polyimides-Review and Update

    Science.gov (United States)

    1989-12-01

    per unit surface area basis). The results of these studies identi- fied two new 3F containing polyimides (3FDA/PPDA and 6F dianhydride ( 6FDA )/ 3FDAM...polymerized with 6FDA in the subsequent study (ref. 8). The three new dialkyl substituted 3F polyimide films were characterized for TOS by TGA and Tg...U’) NASA AVSCOM Technical Memorandum 102353 Technical Report 89-C-017 CN S1 3F Condensation Polyimides - Review and Update William B. Alston

  17. Thermal Properties of Double-Aluminized Kapton at Low Temperatures

    Science.gov (United States)

    Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

    2008-03-01

    Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

  18. Corona-resistance Research of Flat Copper Wire Winded by Polyimide Film%聚酰亚胺薄膜绕包铜扁线耐电晕性能的研究

    Institute of Scientific and Technical Information of China (English)

    刘佳音; 唐文进; 周升; 杨名波; 陈琛

    2014-01-01

    The corona-resistance of flat copper wire winded by polyimide film was analyzed by studying the technology of the flat copper wire. The results show that the main factors influencing the corona-resis-tance are sintering temperature, winding tension and infrared radiation oven temperature. When the sinter-ing temperature is 230℃, winding tension is 8 N, infrared radiation oven temperature is 450℃, the coro-na-resistance of the flat copper wire winded by polyimide film is optimum.%通过对聚酰亚胺薄膜绕包铜扁线的工艺研究,分析了聚酰亚胺薄膜绕包铜扁线的耐电晕性能。结果表明:影响聚酰亚胺薄膜绕包铜扁线耐电晕性能的主要因素为烧结温度、绕包张力和红外辐射炉温度。当烧结温度为230℃,绕包张力为8 N,红外辐射炉温度为450℃时,聚酰亚胺薄膜绕包铜扁线的耐电晕性能最佳。

  19. The hydrolysis of polyimides

    Science.gov (United States)

    Hoagland, P. D.; Fox, S. W.

    1973-01-01

    Thermal polymerization of aspartic acid produces a polysuccinimide (I), a chain of aspartoyl residues. An investigation was made of the alkaline hydrolysis of the imide rings of (I) which converts the polyimide to a polypeptide. The alkaline hydrolysis of polyimides can be expected to be kinetically complex due to increasing negative charge generated by carboxylate groups. For this reason, a diimide, phthaloyl-DL-aspartoyl-beta-alanine (IIA) was synthesized for a progressive study of the hydrolysis of polyimides. In addition, this diimide (IIA) can be related to thalidomide and might be expected to exhibit similar reactivity during hydrolysis of the phthalimide ring.

  20. Synthesis of a new aromatic dianhydride monomer and related polyimide

    Institute of Scientific and Technical Information of China (English)

    Yun Xia Wei; Ming Guang Ma; Guo Hu Zhao; Sheng Ying Li; Ming Kai Chen

    2009-01-01

    A novel aromatic dianhydride monomer,3,3'-oxybis[(3,4-dicarboxyphenoxy)phenol]dianhydride,was successfully synthe-sized in three steps using 3,3'-oxybis(phenol)as starting material,which was reacted with 4,4'-oxydianiline(ODA)via a conventional thermal or chemical imidization method to produce a new polyimide.The resulting polyimide exhibited excellent solubility,and film-forming capability.

  1. Single-grain Si thin-film transistors on flexible polyimide substrate fabricated from doctor-blade coated liquid-Si

    NARCIS (Netherlands)

    Zhang, J.; Trifunovic, M.; Van der Zwan, M.; Takagishi, H.; Kawajiri, R.; Shimoda, T.; Beenakker, C.I.M.; Ishihara, R.

    2013-01-01

    Solution process of silicon will provide high-speed transistor fabrication with low-cost by, for example, roll-to-roll process. In this paper, a low-temperature process (350 °C) is reported for fabrication of high-quality Si devices on a polyimide substrate from doctor-blade coated liquid-Si. With

  2. Single-grain Si thin-film transistors on flexible polyimide substrate fabricated from doctor-blade coated liquid-Si

    NARCIS (Netherlands)

    Zhang, J.; Trifunovic, M.; Van der Zwan, M.; Takagishi, H.; Kawajiri, R.; Shimoda, T.; Beenakker, C.I.M.; Ishihara, R.

    2013-01-01

    Solution process of silicon will provide high-speed transistor fabrication with low-cost by, for example, roll-to-roll process. In this paper, a low-temperature process (350 °C) is reported for fabrication of high-quality Si devices on a polyimide substrate from doctor-blade coated liquid-Si. With t

  3. A thin-film aluminum strain gauges array in a flexible gastrointestinal catheter for pressure measurements

    Science.gov (United States)

    Sousa, P. J.; Silva, L. R.; Pinto, V. C.; Goncalves, L. M.; Minas, G.

    2016-08-01

    This paper presents an innovative approach to measure the pressure patterns associated with the motility and peristaltic movements in the upper gastrointestinal tract. This approach is based on inexpensive and easy to fabricate thin-film aluminum strain gauge pressure sensors using a flexible polyimide film (Kapton) as substrate and SU-8 structural support. These sensors are fabricated using well-established and standard photolithographic and wet etching techniques. Each sensor has a 3.4 mm2 area, allowing a fabrication process with a high level of sensors integration (four sensors in 1.7 cm), which is suitable for placing them in a single catheter. These strain gauges bend when pressure is applied and, consequently, their electrical resistance is changed. The fabricated sensors feature an almost linear response (R 2  =  0.9945) and an overall sensitivity of 6.4 mV mmHg-1. Their readout and control electronics were developed in a flexible Kapton ribbon cable and, together with the sensors, bonded and wrapped around a catheter-like structure. The sequential acquisition of the different signals is carried by a microcontroller with a 10 bit ADC at a sample rate of 250 Hz per-1 sensor. The signals are presented in a user friendly interface developed using the integrated development environment software, QtCreator IDE, for better visualization by physicians.

  4. Steam Pyrolysis of Polyimides: Effects of Steam on Raw Material Recovery.

    Science.gov (United States)

    Kumagai, Shogo; Hosaka, Tomoyuki; Kameda, Tomohito; Yoshioka, Toshiaki

    2015-11-17

    Aromatic polyimides (PIs) have excellent thermal stability, which makes them difficult to recycle, and an effective way to recycle PIs has not yet been established. In this work, steam pyrolysis of the aromatic PI Kapton was performed to investigate the recovery of useful raw materials. Steam pyrolysis significantly enhanced the gasification of Kapton at 900 °C, resulting in 1963.1 mL g(-1) of a H2 and CO rich gas. Simultaneously, highly porous activated carbon with a high BET surface area was recovered. Steam pyrolysis increased the presence of polar functional groups on the carbon surface. Thus, it was concluded that steam pyrolysis shows great promise as a recycling technique for the recovery of useful synthetic gases and activated carbon from PIs without the need for catalysts and organic solvents.

  5. Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Fang-Hsing Wang

    2014-02-01

    Full Text Available In this study, silicon nitride (SiNx thin films were deposited on polyimide (PI substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD system. The gallium-doped zinc oxide (GZO thin films were deposited on PI and SiNx/PI substrates at room temperature (RT, 100 and 200 °C by radio frequency (RF magnetron sputtering. The thicknesses of the GZO and SiNx thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiNx thin films were a working pressure of 800 × 10−3 Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH4 = 20 sccm and NH3 = 210 sccm, respectively. For the GZO/PI and GZO-SiNx/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiNx/PI substrates with thickness of ~1000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiNx/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiNx/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiNx/PI.

  6. Photoimageable Polyimide: A Dielectric Material For High Aspect Ratio Structures

    Science.gov (United States)

    Cech, Jay M.; Oprysko, Modest M.; Young, Peter L.; Li, Kin

    1986-07-01

    Polyimide has been identified as a useful material for microelectronic packaging because of its low dielectric constant and high temperature stability. Difficulties involved with reactive ion etching (RIE), a conventional technique for patterning thick polyimide films (thickness greater than 5 microns) with vertical walls, can be overcome by using photimageable polyimide precursors. The processing steps are similar to those used with negative photoresists. EM Chemical's HTR-3 photosensitive polyimide has been spun on up to a thickness of 12 microns. Exposure with a dose of 780 mJcm-2 of ultraviolet light, followed by spin development produces clean patterns as small as 5 microns corresponding to an aspect ratio of 2.4. When the patterned precursor is heated, an imidization reaction occurs converting the patterned film to polyimide. Baking to ca. 400 degrees C results in substantial loss in the thickness and in line width. However, shrinkage occurs reproducibly so useful rules for mask design can be formulated. Near vertical wall structures can be fabricated by taking advantage of the optical and shrinkage properties of the polyimide precursor. After development, an undercut wall profile can be produced since the bottom of the film receives less exposure and is hence more soluble in the developer. During heating, lateral shrinkage pulls the top of the film inward producing a vertical wall since the bottom is fixed to the substrate by adhesion. As a result, fully cured polyimide structures with straight walls and aspect ratios greater than one can be obtained. Dielectric properties of the fully imidized films were investigated with capacitor test structures. A relative dielectric constant of 3.3 and a loss tangent of .002 were measured at 20 kHz. It was also found that the dielectric constant increases as a linear function of relative humidity.

  7. Effects of Substrate Temperature on Structural and Optical Properties of Spray-Pyrolyzed Cu(Ga0.3In0.7)Se2 Thin Films on Polyimide Plastic Substrate

    Science.gov (United States)

    Faraj, M. G.; Pakhuruddin, M. Z.; Taboada, P.

    2017-08-01

    Chalcopyrite copper indium gallium diselenide Cu(Ga0.3In0.7)Se2 films have been deposited on polyimide (PI) plastic substrate by chemical spray pyrolysis using different substrate temperatures in the range from 350°C to 395°C. The influence of substrate temperature on the structural and optical properties of the CIGS films was studied. High-resolution x-ray diffraction results revealed that the films exhibited chalcopyrite-type structure. The crystallite size of the films increased with increasing substrate temperature, as did their root-mean-square surface roughness. Optical transmission measurements by ultraviolet-visible (UV-Vis) spectrophotometer showed that the optical bandgap decreased from 1.28 eV to 1.16 eV as the substrate temperature was increased. This variation of the crystallite size and energy bandgap with substrate temperature makes such films a promising candidate for application in optoelectronic devices such as photoconductors and solar cells.

  8. Preparation and Properties Study of Polyimide Film Based on Trimethyl-m-phenylenediamine%三甲基间苯二胺型聚酰亚胺薄膜的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    虞鑫海; 虞静远; 许梅芳; 郑秀秀; 徐永芬; 钱明球; 赵炯心

    2013-01-01

      采用2,4,6-三甲基间苯二胺(TMmPDA)、4,4′-二氨基二苯醚(DADPE)和3,3′,4,4′-四羧基联苯二酐(BP-DA)为原料,合成得到了三甲基间苯二胺型聚酰胺酸(TMPAA)溶液,经涂膜、热亚胺化,制得了三甲基间苯二胺型聚酰亚胺(TMPI)薄膜,并对其性能进行了研究。结果表明:三甲基间苯二胺型聚酰亚胺薄膜具有良好的光学透明性、较低的介质损耗、良好的疏水性能,比含羧基聚酰亚胺薄膜具有更好的柔韧性和更高的断裂拉伸强度。%  Using 2,4,6-trimethyl-m-phenylenediamine (TMmPDA), 4,4’-diaminodiphenyl ether (DADPE) and 3,3’,4,4’-tetracarboxylic biphenyl dianhydride (BPDA) as raw material, a polyamide acid (TMPAA) solution was synthesized by condensation reaction, and the corresponding polyimide (TMPI) film was pre-pared by thermal imidization, and its properties were studied. The results show that the TMPI film has good optical transparency, low dielectric loss and low water absorption and has better flexibility and high-er breaking tensile strength than that of the polyimide film containing carboxyl.

  9. Suitability of Different Polyimide Capsule Materials for Use as ICF Targets

    Energy Technology Data Exchange (ETDEWEB)

    Knight, A.K.; Tsai, F.-Y.; Bonino, M.J.; Harding, D.R.

    2004-03-15

    OAK-B135 Previous research efforts to fabricate direct-drive polyimide shells have focused on identifying processes that maximize the mechanical and permeation properties of the polyimide material. A strong correlation exists between these properties and the processing conditions, which is ascribed to the crystallinity and segmental mobility of the polyimide chains. This correlation, together with the range of properties that have been demonstrated, will be reported. For example, the permeability of biaxially strained polyimide is three orders of magnitude higher than that of the normal Kapton formulation, decreasing the necessary fill time from 320 h to 0.66 h for an OMEGA target. Current research efforts focus on improving the smoothness of polyimide shells. The approach is to model the effect of different configurations of the equipment and processing parameters on the impinging mass flux of reactants onto the shell substrates. This is done using both computational fluid dynamics (FLUENT) and Monte Carlo codes to cover the relevant pressure regimes. Both molecular gas dynamics and surface chemistry are included in the models. These models are then cross-referenced to the measured smoothness of the shells.

  10. Synthesis and characterization of novel polyimides based on thiazole-containing diamine

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new kind of aromatic diamine monomer containing thiazole unit, 2-amino-5-(4-aminophenyl)-thiazole (AAPT), was synthesized in three steps, starting from 4-nitroacetophenone. A novel thiazole-containing polyimide was prepared via the polycondensation of AAPT with 6FDA by one-step method. The resulting polyimide exhibits excellent solubility, film-forming capability and high thermal resistance.

  11. Improved Breakdown Voltage in AlGaN/GaN High Electron Mobility Transistors by Employing Polyimide/Chromium Composite Thin Films as Surface Passivation and High-Permittivity Field Plates

    Science.gov (United States)

    Chu, Fu-Tong; Chen, Chao; Zhou, Wei; Liu, Xing-Zhao

    2013-09-01

    The breakdown voltage of AlGaN/GaN high electron mobility transistors (HEMTs) is enhanced by employing metal chromium (Cr) nanoparticle-embedded polyimide (PI) as a high-permittivity (high-K) dielectric covering both the source-gate and gate-drain regions. The PI/Cr composite high-K dielectrics acting as a field plate prevent the occurrence of strong electric fields produced at the drain side edge of the gate electrode to obtain an optimum lateral electric flux of HEMTs. The breakdown voltage is improved by approximately 35% when using the PI/Cr thin film dielectric field plate while maintaining high performance, a high transconductance value of 122.4 mS/mm, and a large saturated drain-current value of 748 mA/mm.

  12. Evaluation of transverse piezoelectric coefficient of ZnO thin films deposited on different flexible substrates: a comparative study on the vibration sensing performance.

    Science.gov (United States)

    Joshi, Sudeep; Nayak, Manjunatha M; Rajanna, K

    2014-05-28

    We report on the systematic comparative study of highly c-axis oriented and crystalline piezoelectric ZnO thin films deposited on four different flexible substrates for vibration sensing application. The flexible substrates employed for present experimental study were namely a metal alloy (Phynox), metal (aluminum), polyimide (Kapton), and polyester (Mylar). ZnO thin films were deposited by an RF reactive magnetron sputtering technique. ZnO thin films of similar thicknesses of 700 ± 30 nm were deposited on four different flexible substrates to have proper comparative studies. The crystallinity, surface morphology, chemical composition, and roughness of ZnO thin films were evaluated by respective material characterization techniques. The transverse piezoelectric coefficient (d31) value for assessing the piezoelectric property of ZnO thin films on different flexible substrates was measured by a four-point bending method. ZnO thin films deposited on Phynox alloy substrate showed relatively better material characterization results and a higher piezoelectric d31 coefficient value as compared to ZnO films on metal and polymer substrates. In order to experimentally verify the above observations, vibration sensing studies were performed. As expected, the ZnO thin film deposited on Phynox alloy substrate showed better vibration sensing performance. It has generated the highest peak to peak output voltage amplitude of 256 mV as compared to that of aluminum (224 mV), Kapton (144 mV), and Mylar (46 mV). Therefore, metal alloy flexible substrate proves to be a more suitable, advantageous, and versatile choice for integrating ZnO thin films as compared to metal and polymer flexible substrates for vibration sensing applications. The present experimental study is extremely important and helpful for the selection of a suitable flexible substrate for various applications in the field of sensor and actuator technology.

  13. Qualification Of Kapton Pretreatment Process Using 3M Scotch Weld 2216 For Solar Panel Application

    Science.gov (United States)

    Swamy, B. R.; Krishna, Priya G.; Venkatesh, K.; Nagendra, H. R.; Nanjundaswamy, T. S.

    2011-10-01

    Substrates for solar arrays intended to be used on satellite systems are generally made of aluminum honeycomb structure sandwiched with Carbon Fiber Reinforced Plastic (CFRP) face skin. Two mil thick KaptonTM sheets are co cured on one side of the aluminum /CFRP composite structure while realizing the substrate panels. This Kapton sheet would serve as an insulator over which solar cell blankets are bonded with suitable adhesive for the satellite solar panels. The satellite solar panels demands highest degree of quality and reliability and one of the prime factors in this regards is the bond strength of adhesive which is used to bond the solar cell blankets. Various methods of pretreatments of Kapton surface are in use for increasing the surface energy, which in turn results in improved bond strengths. These methods generally provide roughened surface of the Kapton which is achieved either by abrasive means like scrubbing the surface using fine silica chip, or plasma etching or alternatively by an additive process wherein suitable polyester, phenolic or other resins are coated on to the Kapton surface to achieve the desired results. For spacecraft solar panel applications at ISRO, polyester resin coating on to the Kapton surface was used as pretreatment prior to adhesive application. This process had provided adequate bond strengths between the solar cells and Kapton. Due to issues related to the supply of the polyester resin material from the vendor alternative methods of pretreatments were explored. In this paper, a novel process developed for Kapton pretreatment is described along with results of relevant qualifications for the satellite solar panel application. This newly developed pretreatment process for Kapton successfully adopts an epoxy based material 3M Scotch weld 2216 which is widely used in spacecraft electronic hardware.

  14. Reinforced Thermoplastic Polyimide with Dispersed Functionalized Single Wall Carbon Nanotubes

    Science.gov (United States)

    Lebron-Colon, Marisabel; Meador, Michael A.; Gaier, James R.; Sola, Francisco; Scheiman, Daniel A.; McCorkle, Linda S.

    2010-01-01

    Molecular pi-complexes were formed from pristine HiPCO single-wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4- N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used. At a loading level of 5.5 wt %, the Tg of the polyimide increased from 169 to 197 C and the storage modulus increased 20-fold (from 142 to 3045 MPa). The addition of 3.5 wt % SWCNT/1 complexes increased the tensile strength of the polyimide from 61.4 to 129 MPa; higher loading levels led to embrittlement and lower tensile strengths. The electrical conductivities (DC surface) of the polyimides increased to 1 x 10(exp -4) Scm(exp -1) (SWCNT/1 complexes loading level of 9 wt %). Details of the preparation of these complexes and their effects on polyimide film properties are discussed.

  15. 聚酰亚胺绝缘膜的真空性能及在电真空器件中的应用研究%Study of Vacuum Properties of Polyimide Insulation Film and Its Application in Vacuum Devices

    Institute of Scientific and Technical Information of China (English)

    李玲珍; 郑姚生

    2001-01-01

    The surface compositions of the polyimide insulation film,its degassing characteristics,and the residual gases compositions during high temperature annealing were studied with solid mass spectrometer and gas mass spectrometer,respectively.The results show that no harmful materials,which may contaminat the cathode,exist in the film;and that the film can be used in vacuum as an insulating material because the average base pressure of the vacuum system after a baking of 300 ℃ is lower than 1.9×10-3 Pa.%利用固体质谱仪和气体质谱仪分别进行了聚酰亚胺绝缘膜的表面成分及在高温烘烤过程中的放气性能和气体成分分析。结果表明,聚酰亚胺材料中不存在污染阴极的有害成分,并且经高温烘烤后,在300 ℃时的平衡压强小于1.9×10-3 Pa。因此,它完全可以作为真空中的绝缘介质材料。

  16. Surface Morphology of Polyimide Thin Film Dip-Coated on Polyester Filament for Dielectric Layer in Fibrous Organic Field Effect Transistor

    Directory of Open Access Journals (Sweden)

    Rambausek Lina

    2014-09-01

    Full Text Available The idea of wearable electronics automatically leads to the concept of integrating electronic functions on textile substrates. Since this substrate type implies certain challenges in comparison with their rigid electronic companions, it is of utmost importance to investigate the application of materials for generating the electronic functions on the textile substrate. Only when interaction of materials and textile substrate is fully understood, the electronic function can be generated on the textile without changing the textile’s properties, being flexible or stretchable. This research deals with the optimization of the dielectric layer in a fibrous organic field effect transistor (OFET. A transistor can act as an electrical switch in a circuit. In this work, the polyimide layer was dip-coated on a copper-coated polyester filament. After thoroughly investigating the process conditions, best results with minimal thickness and roughness at full insulation could be achieved at a dip-coating speed of 50 mm/min. The polyimide solution was optimal at 15w% and the choice for the solvent NMP was made. In this paper, details on the pre-treatment methods, choice of solvent and dip-coating speed and their effect on layer morphology and thickness, electrical properties and roughness are reported. Results show that the use of polyimide as a dielectric layer in the architecture of a fibrous OFET is promising. Further research deals with the application of the semiconductor layer within the mentioned architecture, to finally build an OFET on a filament for application in smart textiles.

  17. Fabrication and properties of polyimide dielectric films via solution polycondensation%溶液缩聚法制备聚酰亚胺绝缘膜及性能研究

    Institute of Scientific and Technical Information of China (English)

    张永爱; 曾祥耀; 周雄图; 郑灼勇; 郭太良

    2012-01-01

    以联苯四酸二酐(BPDA)和4,4’-二氨基二苯醚(ODA)为单体原料,利用溶液缩聚法制备聚酰亚胺(PI)绝缘膜,采用XRD、SEM、FT-IR对不同热亚胺化温度合成的PI薄膜结构和表面形貌进行了表征,利用超高阻微电流测试仪测试了热亚胺化温度和粉体含量对PI绝缘膜击穿场强的影响。结果表明,在真空度为1.0×10-2Pa条件下,300℃热亚胺化1h,聚酰亚胺酸(PAA)薄膜完全被热亚胺化,制备的PI绝缘膜内部结构致密;当BPDA和ODA的粉体含量为5%时,PI绝缘膜击穿场强高达2.15MV/cm,表明PI薄膜具有良好的电学性能。%Biphenyltetracarboxylic dianhydride(BPDA) and 4,4'-diaminodiphenyl ether(ODA) used as monomer reaction products and the polyimide(PI) dielectric films have been successfully fabricated via solution polycondensation.The structure and surface morphology of PI dielectric films prepared in different imidization temperature were characterized by XRD,SEM and FT-IR.The influence that the imidization temperature and powder content(BPDA and ODA) affected on the breakdown field was measured by current testing instrument with high resistance techniques.The experimental results show that polyimide acids(PAA) were completely aminated and become PI dielectric films with compact internal structure after imidization temperature of 300℃ for 1h under vacuum environment of 1.0×10-2Pa.The breakdown field can reach up to 2.15MV/cm when powder content of BPDA and ODA was fixed to 5%,which indicates that PI dielectric films have good electrical properties.

  18. 聚酰亚胺/碳纳米管杂化薄膜电性能的研究%Electrical Properties of Polyimide/Carbon Nano-tube Hybrid Film

    Institute of Scientific and Technical Information of China (English)

    朱小影; 张明艳; 刁鹏鹤; 王文佳; 李晓东

    2011-01-01

    A kind of polyamide acid/carbon nano-tube hybrid liquid cement was fabricated by means of ultrasonic dispersion and in-situ polymerization.Then the polyimide/carbon nano-tube hybrid film was prepared according to filming technology.The surface morphology of the film was characterized by SEM.And the effects of incorporation of carbon nano-tube on the electrical property were researched.The results show that with the increase of CNTs content, the dielectric strength decreases gradually and has a sharp drop when the doped content is close to 0.6%, the dielectric constant and dielectric loss factor increase obviously.With the rise of test frequency, the dielectric constant declines slowly and the dielectric loss factor increases.The corona resistance time of the hybrid film is longer than that of pure polyimide.When the doped content of MWNTs is near to 0.38%, the time of corona resistance reaches a maximum of 10.2 h.%采用超声分散-原位聚合的方法制备聚酰胺酸/碳纳米管(CNTs)杂化胶液,并按一定成膜工艺制备出聚酰亚胺/碳纳米管杂化薄膜.利用扫描电子显微镜(SEM)对薄膜的表面形貌进行表征,讨论了碳纳米管的加入对杂化薄膜电性能的影响.结果表明:随着碳纳米管含量的增加,介电强度降低,介电常数与介质损耗因数均呈上升趋势,且随着测试频率的增加,介电常数缓慢下降,介质损耗因数增加;杂化薄膜的耐电晕性能均高于纯PI,且含量为0.38%时,耐电晕时间达到最大值10.2h.

  19. Fabrication and investigation on properties of barium titanate/titanium carbide/polyimide composite films%钛酸钡/碳化钛/聚酰亚胺三元复合薄膜的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    张大兴

    2013-01-01

    随着微电子工业的不断发展,高介电常数材料的发展已成为制约电子器件微型化、高速化的关键因素之一.本文以钛酸钡核碳化钛为填料,经硅烷偶联剂改性后按一定比例添加到聚酰亚胺中,制备出钛酸钡/碳化钛/聚酰亚胺(BaTiO3/TiC/PI)三元复合薄膜.对复合薄膜的显微结构及性能进行了分析.实验结果表明,无机填料在复合薄膜中具有较好的分散性,说明硅烷偶联剂改性后无机粉体与聚酰亚胺基体的相容性增加.性能测试表明,随着无机填料含量的增加,三元复合薄膜的拉伸强度和断裂伸长率均下降,而导电性能则逐渐提高.%With the development of the microelectronics industry, the development of high dielectric constant materials have become one of the key factors restricting the rapid miniaturization of electronic devices. In this paper, the barium titanate (BaTiO3) and titanium carbide (TiC) are chosen as fillers and added into the polyimide matrix to fabricate the BaTiO3/TiC/PI composite films. The microstructure and properties of the composite films were analyzed. The experimental results showed that the inorganic fillers had a rather good dispersion in the composite film, which should be attributed to the increased compatibility between inorganic powders and polyimide matrix after the inorganic powders were modified by silane coupling agent. The performance test showed that, with the increase of inorganic filler content, the tensile strength and elongation at break of composite films decreased, while the conductivity increase.

  20. Preparation and Characterization of Molybdenum Thin Film to Photovoltaic applications; Preparacion y Caracterizacion de Peliculas Delgadas de Molibdeno para Aplicaciones Fotovoltaicas

    Energy Technology Data Exchange (ETDEWEB)

    Andres, M.; Gutierrez, M. T.

    2007-09-18

    Molybdenum (Mo) is one of the main material used as back ohmic contact for Cu(In,Ga)Se2 (CIGS) thin film solar cells. It has to provide the electrical properties of low resistivity electrode and high reflectance in the absorbance region of CIGS layer. Also, it has to have high thermal stability, an adequate morphology and good adhesion to the substrate. The aim of this work has been the preparation of Mo layers onto two types of substrates, soda-lime glass (SLG) and a commercial flexible polyimide called Kapton, and the evaluation as a flexible substrate in CIGS solar cells. Internal stress, adhesion, microstructure and optical and electrical properties of Mo thin films have been studied as a function of deposition parameters (gas pressure, power density and time). The change of the substrate from rigid one to flexible introduces tensile stress due to the difference in the coefficient of thermal expansion (CTE) between the coating and the substrate. Low stress in Mo/Kapton structure has been obtained; this is a good result to use in CIGS flexible solar cells. (Author) 23 refs.

  1. PI/AlO(OH)-SiO2纳米杂化薄膜的制备及热性能、电性能分析%Preparation of polyimide/AlO(OH)-SiO2 nano hybrid film and analysis on its thermal properties and electrical properties

    Institute of Scientific and Technical Information of China (English)

    赵斯梅

    2015-01-01

    以聚酰亚胺作为高聚物反应基体,通过正硅酸乙酯(TEOS)和异丙醇铝的水解缩合反应,使之和聚酰胺酸发生溶胶-凝胶反应,从而制备出不同比例AlO(OH)-SiO2的聚酰亚胺杂化薄膜。利用原子力显微镜、热失重分析、介电谱和击穿试验对其表观形貌和热性能、电性能进行表征和测试,考察结构与性能之间的关系。%Using polyimide as the matrix resin, polyimide hybrid film with various proportion of AlO(OH)- SiO2 was prepared through the sol- gel reaction of polyimide after the hydrolysis condensation reac⁃tion of traethoxysilane (TEOS) and heteropropyl- aluminium. The surface morphology, thermal property and electrical property of the film were characterized by atomic force microscope (AFM), thermal weight loss and dielectric spectroscope and break down test, and the relationship between the structures and properties of the films were investigated.

  2. Low Permeability Polyimide Insulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Resodyn Technologies proposes a new technology that enables the application of polyimide based cryogenic insulation with low hydrogen permeability. This effort...

  3. 环境温湿度对聚酰亚胺介电强度的影响机制%Influences of Elevated Temperature and Humidity on Breakdown Characteristics of Polyimide Film

    Institute of Scientific and Technical Information of China (English)

    罗杨; 吴广宁; 刘继午; 彭佳; 高国强; 孙继星; 朱光亚

    2014-01-01

    Polyimide (PI) film has been widely applied as electrical insulation for wires and cables due to its excellent electrical, mechanical and thermal properties. However, PI insulation could be degraded because of various environmental stresses, which can cause deterioration of their insulation properties. In this paper, the effects of thermal exposure on dielectric strength of nanocomposite PI film and pure PI film were investigated. The comparison of the breakdown field strength of single layer film, double layer films and three layer films were also studied. The influence mechanism of humidity on the breakdown strength was analyzed. The results show that the breakdown field strength of PI films, both nanocomposite PI film and pure PI film, is greatly decreased with the tested temperature increasing. And the decreasing rate of breakdown field strength increases more obviously when the tested temperature is more than 350℃. It is due to the motion and pyrolysis degradation of PI macromolecules caused by overheating. The single film possesses better heat dissipation potential and homogeneous micro-structure. Therefore the breakdown field strength of single layer film is higher than those of double layer films and three layer films. Higher thermal conductivity of nanocomposite PI film has the better breakdown stability in high temperature environment. Some hydrogen bonds exist between water molecule and carboxyl in the backbone chain of PI polymer. The hydrolysis reaction of PI macromolecule would make the dielectric strength of PI film decrease.%聚酰亚胺薄膜因其优良的电气、机械及热性能已在各种绝缘线缆中得到广泛应用。然而,环境应力可能会造成聚酰亚胺降解,从而降低其绝缘性能。以聚酰亚胺普通薄膜和聚酰亚胺纳米薄膜为测试对象,研究了单层膜、双层膜及三层膜在不同温度下的击穿特性,分析了水分对聚酰亚胺薄膜击穿场强的影响机制。结果表明:普

  4. A study on the preparation of the exfoliated polyimide nanocomposite and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, S.G.; Park, D.Y.; Kim, Y.S. [Yeungnam University, Kyongsan (Korea); Lee, Y.C. [Korea Institute of Industrial Technology, Chonan (Korea); Sur, G.S. [Yeungnam University, Kyongsan (Korea)

    2002-05-01

    Diamines (p-phenylenediamine, m-phenylenediamine, and n-hexamethylenediamine) were intercalated into sodium montmorillonite for the further reaction with the anhydride end groups of polyamic acid. The anhydride terminated polyamic acid was synthesized using a mole ratio of 4,4'-oxydianilline : 1,2,4,5-benzene tetracarboxylic dianhydride = 1.50 : 1.53. The modified montmorillonite was reacted with polyamic acid terminated with anhydride group in N-methyl-2-pyrrolidone (polyamic acid/clay nanocomposite). After imidization, thin films of the polyimide/clay nanocomposite were prepared. From the results of XRD and TEM, we found that mono layered silicated were dispersed in polyimide matrix and those resultants were exfoliated nanocomposites. Mechanical properties of exfoliated polyimide nanocomposite were better than both those of pure polyimide and those of intercalated polyimide nanocomposite. (author). 13 refs., 1 tab., 5 figs.

  5. Properties and Adhesion of Polyimides in Microelectronic Devices

    Science.gov (United States)

    1990-08-15

    PMDA-ODA poly- imide films are spin coating (SC) and vapor deposition polymerisation (VDP) . They differ in the way the film pre- cursor (polyamic...where they react at room temperature to polyamic acid. Spin coating (SC) requires that the polymer precursor polyamic acid is applied in a polar...The polyimide substrates were prepared by spin coating polyamic acid onto a substrate followed by solvent extrac- tion, imidization and curing at

  6. Study on Electrical Properties of Polyimide/Silica Composite Films%聚酰亚胺/二氧化硅复合薄膜电学性能的研究

    Institute of Scientific and Technical Information of China (English)

    严伟兴; 冯小明; 张营堂

    2012-01-01

    用均苯四甲酸二酐(PMDA)与4,4'-二氨基二苯醚(ODA)为单体,以N,N-二甲基乙酰胺(DMAC)为溶剂,通过超声机械共混法制备聚酰亚胺/二氧化硅(PI/SiO2)复合薄膜,采用红外光谱(FTIR)、扫描电镜(SEM)分别对PI复合薄膜的结构和表面形貌进行了研究表征,通过concept 80宽带介电谱测试系统对复合薄膜电学性能进行了研究.结果表明:在一定的频率下,不同无机纳米粒子含量的复合薄胰中,介电常数和介电损耗角正切随无机纳米质量分数的增加而增大.%With pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA) as monomers, N,N-dimethylacetamide(DMAC) as solvent, polyimide/nano-silica composition film was prepared by means of ultrasonic mechanical mixing method. The structure and surface morphology of PI composite film was examined and characterized by FTIR and SEM, and the electrical properties was also researched by use of concept 80 broadband dielectric spectroscopy test system. The results show that under the conditions of a certain frequency and composite film containing different content of inorganic nano-particles, the dielectric constant and the dielectric loss angle tangent improve with the increasing of content of inorganic nano-particles.

  7. Polyimide-coated fiber Bragg grating for relative humidity sensing

    Science.gov (United States)

    Lin, Yao; Gong, Yuan; Wu, Yu; Wu, Huijuan

    2015-03-01

    A fiber-optic humidity sensor has been fabricated by coating a moisture sensitive polymer film to the fiber Bragg grating (FBG). The Bragg wavelength of the polyimide-coated FBG changes while it is exposed to different humidity conditions due to the volume expansion of the polyimide coating. The characteristics of sensors, including sensitivity, temporal response, and hysteresis, were improved by controlling the coating thickness and the degree of imidization during the thermal curing process of the polyimide. In the relative humidity (RH) condition ranging from 11.3% RH to 97.3% RH, the sensitivity of the sensor was about 13.5 pm/% RH with measurement uncertainty of ±1.5% RH.

  8. Polyimide foam-like microstructures: technology and mechanical properties

    Science.gov (United States)

    Dobrzynska, J. A.; Joris, P.; Jiguet, S.; Renaud, P.; Gijs, M. A. M.

    2011-10-01

    We report a process for the realization of polyimide films with custom-designed microporosity based on the heat-induced depolymerization of polyimide-embedded polypropylene carbonate microstructures. The foam-like microstructures are up to 40 µm thick and incorporate air cavities with a width ranging from 20 to 200 µm, a length up to 5 mm and a height of 20 µm. We model the mechanical stress-strain properties of the microcavities using both analytical and numerical methods. The simulation data are in good agreement with the results of nanoindentation and microcompression experiments, which show the reduction of the effective Young's modulus from 5.77 ± 0.06 GPa for bulk polyimide to 2.51 ± 0.03 GPa for a foam-like layer.

  9. Progress in Polyimide Films for Two-Layer Type Flexible Copper Clad Laminate%二层型挠性覆铜板用聚酰亚胺的研究进展

    Institute of Scientific and Technical Information of China (English)

    刁恩晓; 李帆; 舒适; 肖炳瑞; 黄永发; 王平; 刘峰

    2015-01-01

    The fast development of electronic industry puts forward higher requirements for the property of flexible copper clad laminate (FCCL). The research progress of two-layer type FCCL, which using polyimide film as substract, was reviewed from improving the adhesive property, dielectric property and heat resistance, and the research directions of two-layer type FCCL were proposed.%电子行业的快速发展对二层型挠性覆铜板的性能提出了更高的要求,针对以聚酰亚胺薄膜为基底材料的二层型挠性覆铜板,分别从改善粘结性能、介电性能和耐热性能3个方面综述了二层型挠性覆铜板的研究进展,并展望了二层型挠性覆铜板的研究方向。

  10. Approaches to Pendent Groups' Functionalization of Polyimide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Pendent groups' functionalization of polyimide is an optimum approach to improve its processability and achieve functionalized polyimide materials. There are two types of modification routes for pendent groups functionalization of polyimide: monomer route and macromolecular route. In this paper, various approaches for pendent groups' functionalization of polyimide are introduced. At the same time, a new method to achieve functional polyimide materials without decreasing its thermal stability and mechanical properties is mentioned.

  11. Hollow Polyimide Microspheres

    Science.gov (United States)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2001-01-01

    A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 micrometers, a density of about 1 to about 6 pounds/cubic foot and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bonded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/cubic feet and a compression strength of about 100 to about 1400 pounds/sq inch.

  12. 纳米锆-铝复合氧化物杂化聚酰亚胺耐电晕薄膜的研究%Study on Nano Zr-Al Composite Oxide Hybrid Polyimide Corona Resistant Films

    Institute of Scientific and Technical Information of China (English)

    范勇; 赵伟; 杨瑞宵; 陈昊; 张树龙

    2015-01-01

    采用微乳化-热液法制备了一系列经自制偶联剂处理的纳米锆-铝复合氧化物分散液,采用原位聚合法制备了纳米锆-铝复合氧化物杂化聚酰亚胺复合薄膜,对纳米分散液及复合薄膜的掺杂层进行透射电镜测试,并对复合薄膜的高温耐电晕性能、电气强度、力学性能进行测试及分析。结果表明:分散液中纳米粒子的尺寸达到纳米级,纳米锆-铝复合氧化物杂化PI薄膜的耐电晕性能大幅提高;在固定无机物掺杂量为22%,Zr与Al的物质的量之比为1.2∶9时,PI薄膜的耐电晕寿命达到10.35 h,电气强度达到274.91 MV/m,拉伸强度为146.4 MPa,断裂伸长率为43.0%。%A series of nano Zr-Al composite oxide dispersions were preprared by microemulsion-hydrother-mal method and treated with homemade coupling agent, and then nano Zr-Al complex oxide hybrid poly-imide composite films were prepared via in-situ polymerization. The nano-dispersion and doped layer of the composite films were tested by TEM, and the corona resistance at high temperature, electric strength, and mechanical properties of the composite films were tested and analyzed. The results show that the size of nanoparticles in dispersion reaches nanometer, and the corona resistance of the nano Zr-Al com-posite oxide hybrid PI films is greatly improved. When the doping amount of inorganic compounds is 22% and the molar ratio between Zr and Al is 1.2∶9, the corona resistance life of the hybrid PI film reaches 10.35 h, the electric strength reaches 274.91 MV/m, the tensile strength is 146.4 MPa, and the elongation at break is 43.0%.

  13. Dielectric Property Study of Zirconia/Nano-alumina Hybrid Polyimide Film%氧化锆复配纳米氧化铝杂化聚酰亚胺薄膜的介电性能研究

    Institute of Scientific and Technical Information of China (English)

    范勇; 韩笑笑; 陈昊; 杨瑞宵

    2013-01-01

      采用微乳化-热液法制备了一系列氧化锆(ZrO2)改性的纳米氧化铝分散液,然后用原位聚合法制备了相应的氧化锆复配纳米氧化铝杂化聚酰亚胺复合薄膜,并对其进行了TEM表征、电气强度和电导电流测试以及电老化阈值分析。结果表明:掺杂氧化锆复配纳米氧化铝的杂化聚酰亚胺复合薄膜的电气强度大幅提高,当ZrO2的掺杂量为7%时,电气强度达到最高为396.8 MV/m;其电导电流密度、电老化阈值均高于只掺杂纳米氧化铝的聚酰亚胺薄膜,且随ZrO2含量增加均出现先增大后减小的趋势。%A series of nano-alumina dispersed solution modified by zirconia were prepared by micro emul-sion-hydrothermal method, and a zirconia/nano-alumina hybrid polyimide(PI) film was prepared through in-situ polymerization method, and then the films were characterized by TEM, and its electric strength, conduction current density and electric degradation threshold were analyzed. The results show that the doping of zirconia/nano-alumina can increase the electric strength of the film. When the ZrO2 doping con-tent is 7%, the electric strength attain maximum which is 396.8 kV/mm. The conduction current density and electric degradation threshold of the zirconia/nano-alumina hybrid PI films are higher than that of the PI film doped by nano-alumina only, and they increase first and then decrease with the increase of ZrO2 content.

  14. The Effects of Coupling Agents on the Properties of Polyimide/Nano-Al2O3 Three-Layer Hybrid Films

    Directory of Open Access Journals (Sweden)

    Lizhu Liu

    2010-01-01

    Full Text Available PI/nano-Al2O3 hybrid films were prepared by ultrasonic-mechanical method. Before addition, nano-Al2O3 particles were firstly modified with different coupling agents. The micromorphology, thermal stability, mechanical properties, and electric breakdown strength of hybrid films were characterized and investigated. Results indicated that nano-Al2O3 particles were homogeneously dispersed in the PI matrix by the addition of coupling agents. The thermal stability and mechanical properties of PI/nano-Al2O3 composite films with KH550 were the best. The tensile strength and elongation at break of PI composite film were 119.1 MPa and 19.1%, which were 14.2% and 78.5% higher than unmodified PI composite film, respectively.

  15. Soluble Polyimides Bearing Long-Chain Alkyl Groups on Their Side Chain via Polymer Reaction

    Directory of Open Access Journals (Sweden)

    Yusuke Tsuda

    2012-01-01

    Full Text Available Novel soluble polyimides having long-chain alkyl groups on their side chain were synthesized via polymer reaction with the polyimides having phenolic OH groups and 3,4,5-tris(dodecyloxybenzoic acid (12GA using N,N′-dicyclohexylcarbodiimide (DCC as a dehydration reagent. The polyimides having phenolic OH groups were synthesized from the tetracarboxylic dianhydrides such as 5-(2,5-dioxotetrahydrofuryl-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (cyclohexene-DA, 4,4′-hexafluoroisopropylidendi(phthalic anhydride (6FDA, and 3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA and aromatic diamines such as 4,4′-diamino-3,3′-dihydroxybiphenyl (HAB. The polymer reactions were carried out in NMP and the progresses of polymer reactions were quantitatively monitored by 1H NMR measurements (conversion; 12.2–98.7%. The obtained polyimides bearing long-chain alkyl groups have enough molecular weights, good film-forming ability, good solubility for various organic solvents, and enough thermal stability. The water contact angles of the polyimide films were investigated, and it is noted that the introduction of long-chain alkyl groups increases the hydrophobicity of polyimide surface. These polyimides are expected to be applicable as the functional materials for microelectronics such as the alignment layers of LCDs.

  16. Polyimide/graphene nanocomposite materials to construct a low resistive RPC

    Science.gov (United States)

    Han, R.; Yan, J. Y.; Tian, G. F.; shen, Z. C.; Liao, B.; Liu, Q.

    2016-11-01

    The development of low resistivity material to increase the rate capability of Resistive Plate Chambers (RPCs) has been attracting more and more attention recently. This paper presents a new type of such a material. The new material is based on polyimide doped with carbon. The electrical volume resistivity of this material could be controlled using different percentages of the doping carbon. The standard thickness of polyimide carbon films is around 40 μm which does not allow to use it as such to build the RPC electrodes. To overcome this, we developed a new stress method to make the gap between two polyimide carbon films. In this paper we will introduce the new detector material, the new type of RPC and the cosmic bench test results. In the future, if the polyimide is widely used in RPCs, the electrical properties changed by high energy particles should be well-studied.

  17. Synthesis and characterization of fluorinated polyaminoquinones and fluorinated polyimides

    Science.gov (United States)

    Vaccaro, Eleonora

    Phenolic and quinonoid compounds are widely studied in biological sciences because of their ability to chelate heavy metals like iron and copper and recently have found new applications in synthetic macromolecules. Amino- p-benzoquinone polymers, poly[(2,5-hexamethylenediamino)-1,4-benzoquinone] and poly {[2,5-(2,2'-bistrifluoromethyl)-4,4' -biphenylenediamino]1,4-benzoquinone}, were synthesized and evaluated as adhesion promoters for steel/epoxy joints. An improvement in the torsional shear strength of these joints was observed when these polymers were used as adhesion promoters. The durability of the adhesive bond was also improved after boiling water treatment, relative to untreated and silane treated joints. The improvement in adhesion could be attributed to the formation of a chelate between the polyaminoquinone (PAQ) and the iron surface and a chemical reaction between the PAQ and the epoxy resin. A low molecular weight model compound, bis[2,5-(4-methylanilido)]-1,4-benzoquinone was also used to study coupling between the epoxy adhesive and the steel surface. Electron spin resonance (ESR), atomic absorption spectroscopy and infrared spectroscopy were used to document the epoxy-coupling agent reaction and the chelate formation. Polyimides have acquired importance in the last twenty years as the most promising macromolecules for high technology applications in new materials. Their good thermo-oxidative stability is well known, as well as their high glass transition temperature. Polyimides are versatile polymers, which can be utilized for a wide range of applications: i.e., as matrices for high performance advanced composite materials, as thin films in electronic applications, as structural adhesives and sealants and as membranes for gas separation. A novel anhydride, 1,1,1-trifluoromethyl-1-pentafluorophenylethylidene-2,2-diphthalic anhydride, 8FDA, was synthesized. Five diamines were used in the synthesis of polyimides, namely p-phenylene diamine, 3

  18. Polyimide membranes for alcohols dehydration: from basic aspects to separation applications

    OpenAIRE

    Leo, Mariangela

    2011-01-01

    The first part of this work aimed to the determination of the absorption and desorption kinetics of an alcohol (methanol) inside a commercial polyimide (PMDA ODA) and to the identification of the interactions with polymeric network. The understanding of the molecular mechanisms of diffusion can be helpful in designing the chemical structure of future polymers for optimal transport properties. The diffusion of methanol into polyimide films was studied by in situ FTIR spectroscopy, one of th...

  19. Synthesis of a New Aromatic Dianhydride Containing Pyridine Ring and Related Polyimide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new aromatic dianhydride monomer containing pyridine moiety, 2,6-bis[4'-(3",4"dicarboxyphenoxy)benzoyl]-pyridine dianhydride (Md), was synthesized in four steps, starting from 2,6-pyridinedicarboxyl chloride. A novel pyridine-containing polyimide was prepared via polycondensation of Md with ODA by two-step method. The resulting polyimide exhibits excellent solubility, film-forming capability and high thermal resistance.

  20. Synthesis of a new pyridine-containing diamine and related polyimide

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A new kind of aromatic diamine monomer containing pyridine unit,2,6-bis[4-(4-aminophenoxy)phenoxy]pyridine(BAPP),was synthesized in three steps,using hydroquinone as starting material.A novel pyridine-containing polyimide was prepared from the resulting diamine BAPP with 4,4'-oxydiphthalic anhydride(ODPA) via a conventional two-step thermal imidization method.The resulting polyimide exhibits excellent solubility,film-forming capability and high thermal resistance.

  1. Investigation of the Periodic Microstructure Induced by a 355 nm UV Polarized Laser on a Polyimide Surface

    Institute of Scientific and Technical Information of China (English)

    李梅; 路庆华; 印杰; 罗售余; 王宗光

    2002-01-01

    We investigate a periodic microstructure induced by a 355 nm ultraviolet polarized laser on a polyimide surface and the dependence of the structures on laser parameters. Laser-induced periodic surface structures (LIPSS) of sub-micrometre size were generated on three kinds of polyimide films by a polarized Nd:YAG laser of 355nm within a wide range of laser fluence. The chemical structure of the polyimide, the film-making process, the number of laser pulses and the laser fluence greatly influenced the formation of LIPSS. The periodicity of LIPSS was decided by the wavelength, the incidence angle of the laser beam and the apparent refractive index of the material.

  2. High performance thin film transistor (flex-TFT) with textured nanostructure ZnO film channel fabricated by exploiting electric double layer gate insulator

    Science.gov (United States)

    Ghimire, Rishi Ram; Raychaudhuri, A. K.

    2017-01-01

    We report a flexible thin film transistor (flex-TFT) fabricated on a commonly available polyimide (Kapton®) tape with a channel of highly textured nanocrystalline ZnO film grown by pulsed laser deposition. The flex-TFT with an electric double layer (EDL) gate insulator shows a low threshold for operation (Vth ≤ 1 V), an ON/OFF ratio reaching ≈107 and a subthreshold swing ≈75 mV/dec. The superior performance is enabled by a high saturation mobility (μs ≈ 70 cm2/V s) of the highly textured nanocrystalline channel. The low Vth arises from large charge density (≈1014/cm2) induced into the channel by EDL gate insulator. The large charge density induced by the EDL gate dielectric also enhances the Hall mobility in the film and brings down the sheet resistance by nearly 2 orders, which leads to large ON/OFF ratio. The flex-TFT operation can be sustained with reproducibility when the TFT is bent down to a radius of curvature ≈2 cm.

  3. Channel-optical-waveguide fabrication based on electron-beam irradiation of polyimides

    Science.gov (United States)

    Maruo, Yasuko Yamada; Sasaki, Sigekuni; Tamamura, Toshiaki

    1995-02-01

    A new-channel-waveguide-fabrication process for use with polyimide is described. The new technique uses an electron-beam-induced effect to alter the refractive index of the polyimides directly. Channel waveguides with an 8- mu m-wide, 8- mu m-deep core have been fabricated on a polyimide film by the use of electron-beam irradiation. Only one kind of polyimide (6FDA/TFDB) was used in this waveguide. The difference in refractive index between the core and the cladding was approximately 0.30% for both TE-and TM-polarized incident light when the dose was 1500 mu C/cm2, which was sufficient to produce waveguides. The optical properties of the waveguide are also demonstrated.

  4. TRANSIMIDIZATION IN THERMOPLASTIC POLYIMIDES

    Institute of Scientific and Technical Information of China (English)

    Yoan Kim; Mingming Guo; Lei Zhu; Doyun Kim; Frank W.Harris; Stephen Z.D.Cheng

    1999-01-01

    In order to improve the processibility in thermoplastic polyimides, a new method, termed the "reactive plasticizer" approach, has been proposed. This method uses a small amount (5~15 mol%) of a less activated, weak nucleophilic diamine co-monomer as a "reactive plasticizer" to obtain copolyimide resins which possess relatively low viscosity at low temperatures and can be readily processed through the autoclave cycle at low pressures. During a high temperature treatment, the reactive plasticizers join the reaction to form high molecular weight copolyimides, and the preferred material properties are thus achieved. The most effective reactive plasticizer is aromatic heterocyclic diamines, such as 2, 6-diaminopyridine diamine (DAP),and the transimidization involved with a reactive plasticizer has been proposed to play a major role for the success of this approach. In order to understand the transimidization mechanism, three steps have been taken in this research: first, a copolyimide system of 50% of DAP and 50% 1, 4-bis[4-aminophenoxy]benzene diamine (DODA) with 100% of 2, 2'-bis[4-(3, 4-dicarboxyphenoxy)phenyl] propane dianhydride (Ultem(R)DA) is prepared. Second, several specifically designed polyimide mixture systems were used, and they consist of two homopolyimides: one is Ultem(R) DA-DODA, and the other is Ultem(R) DA-DAP. The third step is to investigate two mixture systems in which Ultem(R) DA-DODA is mixed with DAP monomer solution and Ultem(R) DA-DAP is mixed with DODA monomer solution. For all systems, with increasing degree of transimidization upon heat-treatment, the chain structures of the mixtures and their thermal and dynamic mechanical transition behaviors are investigated via one-dimensional and two-dimensional nuclear magnetic resonance, differential scanning calorimetry, and dynamic mechanical analysis experiments. Experimental results indicate that in the mixture of two homopolyimides, transimidization takes place much more efficiently in

  5. Aerospace applications of PMR polyimide composites

    Science.gov (United States)

    Serafini, T. T.

    1985-01-01

    The current status of the novel class of processable, addition-type polyimides known as PMR (for in situ polymerization of monomer reactants) polyimides, developed by NASA at the Lewis Research Center, is reviewed. Highlights of PMR technology studies conducted at NASA Lewis are presented. Several examples of industrial applications of PMR-15 polyimide composites to aerospace structural components are examined.

  6. Changes of the Electrical and Optical Character of Polyimide Films (and the Chemistry that Drives Them) Due to Exposure to High Energy GEO-like Electrons

    Science.gov (United States)

    2015-10-18

    observations to identify and track both known and unknown spacecraft. We are presenting work to quantify the changes in total reflection and...from 40 keV to 7 MeV available in the model) to arrive at a total dose rate of 0.215 Gy/s delivered by electrons to PI< 50 µm thick on orbit. The...34Charge trapping in corona -charge polyethylene films," Journal of Physics D: Applied Physics, vol. 13, p. 1343, 1980. [20] R. Li, C. Li, S. He, M. Di

  7. Tribological Property of Polyimide Porous Materials

    Institute of Scientific and Technical Information of China (English)

    PU Yu-ping; L(U) Guang-shu; LI Xiao-jun; XIAO Han-cheng

    2006-01-01

    The friction performance of the polyimide (PI) porous composite materials made by moulding method with MoS2 or polytetrafluoroethylene (PTFE) appended are disserted. The result shows that all the PI-based porous composites have the performance of transfer lubrication in the friction process, and the transfer film is built between the counter friction bodies; with the increasing of the MoS2 a mount from 0 to 20%, the friction coefficient trends toward decrease, and the tr ansfer lubricate phenomenon become more obvious; when adding PTFE as synergist t o the porous PI+MoS2 composite material, the synergistic effect happens, which can improve the friction performance of the material effectively.

  8. Polyimide Cellulose Nanocrystal Composite Aerogels

    Science.gov (United States)

    Nguyen, Baochau N.; Meador, Mary Ann; Rowan, Stuart; Cudjoe, Elvis; Sandberg, Anna

    2014-01-01

    Polyimide (PI) aerogels are highly porous solids having low density, high porosity and low thermal conductivity with good mechanical properties. They are ideal for various applications including use in antenna and insulation such as inflatable decelerators used in entry, decent and landing operations. Recently, attention has been focused on stimuli responsive materials such as cellulose nano crystals (CNCs). CNCs are environmentally friendly, bio-renewable, commonly found in plants and the dermis of sea tunicates, and potentially low cost. This study is to examine the effects of CNC on the polyimide aerogels. The CNC used in this project are extracted from mantle of a sea creature called tunicates. A series of polyimide cellulose nanocrystal composite aerogels has been fabricated having 0-13 wt of CNC. Results will be discussed.

  9. Physical and chemical response of 70 MeV carbon ion irradiated Kapton-H polymer

    Indian Academy of Sciences (India)

    H S Virk; P S Chandi; A K Srivastava

    2001-10-01

    Physical and chemical responses of 70 MeV carbon ion irradiated Kapton-H polymer were studied by using UV-visible, FTIR and XRD techniques. The ion fluences ranging from 9.3 × 1011–9 × 1013 ions cm–2 were used. Recorded UV-visible spectra clearly showed a decrease in absorption initially with fluence, but for the higher fluences it showed a recovery characteristic. A decrease in band-gap energy of 0.07 eV was observed. The FTIR analysis indicated the high resistance to radiation induced degradation of polymer. The diffraction pattern of Kapton-H indicates that this polymer is semi-crystalline in its nature. In case of irradiated one, there was an average increase of crystallite size by 20%, but diffuse pattern indicates that there was a decrease in crystallinity, which may be attributed to the formation of complex structure induced by the cross-linking of the polymeric chains.

  10. Cu(In,Ga)S2, Thin-Film Solar Cells Prepared by H2S Sulfurization of CuGa-In Precursor

    Science.gov (United States)

    Dhere, Neelkanth G.; Kulkarni, Shashank R.; Chavan, Sanjay S.; Ghongadi, Shantinath R.

    2005-01-01

    Thin-film CuInS2 solar cell is the leading candidate for space power because of bandgap near the optimum value for AM0 solar radiation outside the earth's atmosphere, excellent radiation hardness, and freedom from intrinsic degradation mechanisms unlike a-Si:H cells. Ultra-lightweight thin-film solar cells deposited on flexible polyimide plastic substrates such as Kapton(trademark), Upilex(trademark), and Apical(trademark) have a potential for achieving specific power of 1000 W/kg, while the state-of-art specific power of the present day solar cells is 66 W/kg. This paper describes the preparation of Cu-rich CuIn(sub 1-x)Ga(sub x)S(sub 2) (CIGS2) thin films and solar cells by a process of sulfurization of CuGa-In precursor similar to that being used for preparation of large-compact-grain CuIn(sub 1-x)Ga(sub x)Se2 thin films and efficient solar cells at FSEC PV Materials Lab.

  11. Neon transport in selected organic composites. [stopping power of Kapton and polyethylene

    Science.gov (United States)

    Townsend, L. W.; Wilson, J. W.; Bidasaria, H. B.

    1984-01-01

    An energy-dependent, perturbation expansion solution for heavy-ion transport in one dimension was used to calculate the dose from Ne-20 beams at incident kinetic energies of 350, 670, and 2000 MeV/amu onto selected organic composites. Transport coefficients, applicable to arbitrary ion beams over a broad range of energies, are presented. Polyethylene and Kapton were tested as constituents of multilayered shielding for spacecraft and astronauts.

  12. Preparation and Properties of Novel Polyimide Film with Maleimide Side Groups%马来酰亚胺侧基聚酰亚胺薄膜的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    虞鑫海; 许梅芳; 樊良子; 徐永芬; 陈武荣; 李立严

    2011-01-01

    利用2,2-双[4-(2,4-二氨基苯氧基)苯基]丙烷(BDAPPP)单体、马来酸酐(MA)、4,4’-二氨基二苯醚( 44ODA)及3,3’,4,4’-四羧酸联苯二酐(BPDA)合成制得马来酰胺酸侧基的聚酰胺酸树脂(MPAA)溶液,经涂膜,热亚胺化,得到坚韧透明的马来酰亚胺侧基聚酰亚胺薄膜(MPI),并对其性能进行研究.结果表明:马来酰亚胺侧基聚酰亚胺薄膜(MPI)具有较低的表面能(34.4 mJ/m2)、较低的吸水率(0.12%)以及良好的紫外吸收性能和较高的可见光透过性(88%),且具有良好的电容、介电损耗稳定性,几乎不受工作频率的影响,对其在高低频环境下的应用非常有利.%Based on the monomers of 2, 2-bis[4-(2, 4-diaminophenoxy) phenyl] propane(BDAPPP), maleic anhydride (MA), 4, 4'-diaminodiphenyl ether(44ODA) and 3, 3', 4, 4'-tetracarboxylbiphenyl di-anhydride(BPDA), a novel polyamic acid solution with maleimide side groups(MPAA) was synthesized. The transparent and tenacious polyimide film with maleimide side groups (MPI) was prepared through imidized process of the MPAA thin layer, and then the properties of the MPI were studied. The results show that the MPI has low surface energy(34.4 mJ/ m2), low water absorption (0.12%), good ultraviolent absorbability, high visible light transparency, and excellent stability of capacitance and dielectric loss within a wide frequency range of 100 kHz~1 MHz.

  13. 侧链密度对聚酰亚胺取向膜性能的影响%Effect of Side Chain Density of Polyimides on Properties of Liquid Crystal Alignment Film

    Institute of Scientific and Technical Information of China (English)

    刘明; 孙振; 汪映寒

    2013-01-01

    4-dodecyloxy-phenyl-4',4"-diaminotriphenylamine (DPDTA) containing triphenylamine were successfully synthesized. Polyimides (PIs) containing triphenylamine units in the main chain were synthesized with the co-condensation of DMMDA,DPDTA and aromatic dianhydride 4 ,4'- oxydiphthalic anhydride (ODPA) by thermal imidization. The structures of the PIs were confirmed by FT-IR. The alignment behavior of PIs as liquid crystal alignment layers was also examined with polarized optical micrograph (POM). The properties of the PIs were characterized by TGA,UV-Vis and DSC etc. It was found that side chain density of PIs had important influence on properties of liquid crystal alignment film. Before rubbing,PI containing 25% DPDTA could induce uniform vertical alignment and a pretilt angle of 89. 7°. The liquid crystal was not aligned on the surface of PI film which contained 10% DPDTA without the rubbing treatment. After the rubbing process,the pretilt angle of liquid crystal was 2. 4,when PI film contained 25% DPDTA and the pretilt angle of liquid crystal was 1. 8% when PI contained 10% DPDTA. The transmittances of the Pis in 500~800 nm wavelengths are more than 80%,and their glass transition temperatures are above 230 ℃.%成功地合成了二胺单体十二烷氧基苯-4',4"-二氨基三苯胺(DPDTA),并用此单体与3,3′-二甲基-4,4'-二氨基二苯甲烷(DMMDA)和二苯醚四羧酸二酐(ODPA)共缩聚,采用低温缩聚-热酰亚胺化、通过调节共聚物组成制备了2种聚酰亚胺(PI).利用FT-IR、NMR、UV-Vis与DSC等手段对合成二胺单体及PI进行了结构表征和性能测试.研究了其取向性能、透光性能和耐热性能.结果表明,在摩擦前,含10% DPDTA的PI不能诱导液晶分子取向,含25%DPDTA的PI能诱导液晶分子垂直取向,预倾角可达89.6..而摩擦后,两种PI都能使液晶分子平行取向,预倾角分别为1.8°和2.4°.两种PI膜在500~800 nm区域透光率都在80

  14. Direct hot embossing of microelements by means of photostructurable polyimide

    Science.gov (United States)

    Akin, Meriem; Rezem, Maher; Rahlves, Maik; Cromwell, Kevin; Roth, Bernhard; Reithmeier, Eduard; Wurz, Marc Christopher; Rissing, Lutz; Maier, Hans Juergen

    2016-07-01

    While automatic hot embossing systems are available for large- and small-scale productions of polymeric devices, one of the process challenges remains to be the manufacturing of precise, durable, and yet inexpensive hot embossing stamps. The use of metallic stamps manufactured by electroplating a photoresist pattern or by precision milling and their replication into silicone molds with UV-lithography, electroplating, and molding techniques is state of the art. Yet, there have been few, if any, thriving attempts to directly emboss polymers by means of bare photoresists, and in particular polyimide-based photoresists, without transferring the photoresist patterns into a different stamp material. We conduct a proof-of-concept by developing hot embossing stamps based on photosensitive polyimide. We focus primarily on the reliability of the aforementioned stamps throughout the hot embossing cycle and the fidelity of pattern transfer onto polymeric films for different microstructural patterns.

  15. Influence of the Viscoelastic Properties of the Polyimide Dielectric Coating on the Wafer Warpage

    Science.gov (United States)

    Zhu, Chunsheng; Ning, Wenguo; Xu, Gaowei; Luo, Le

    2014-09-01

    Polyimide is widely used as the dielectric material in wafer level packaging. One potential problem with its application is the warpage and stress generated in the curing process. This paper investigated the material properties of polyimide and its influence on the wafer warpage. The viscoelastic properties of polyimide film were measured and a mathematical model of the properties was developed. Finite element analysis of the wafer warpage was performed and this indicates that the viscoelastic material model gave the best prediction. To better understand the causation of the warpage, curvature evolution of the polyimide-coated silicon wafer during its curing process was measured by a multi-beam optical sensor system. It was found that the warpage was mainly induced by the coefficient of thermal expansion mismatch and that the cure shrinkage of polyimide had little effect. Additionally, the effect of the cooling rate on the wafer warpage was also studied. Both simulation and experiment results showed that a slower cooling rate in the temperature range around the glass transition temperature ( T g) of polyimide will help to reduce the final wafer warpage.

  16. 3D Printing All-Aromatic Polyimides using Mask-Projection Stereolithography: Processing the Nonprocessable.

    Science.gov (United States)

    Hegde, Maruti; Meenakshisundaram, Viswanath; Chartrain, Nicholas; Sekhar, Susheel; Tafti, Danesh; Williams, Christopher B; Long, Timothy E

    2017-08-01

    High-performance, all-aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4'-oxydianiline (PMDA-ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all-aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy-intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity. This study demonstrates the unprecedented 3D printing of PMDA-ODA using mask-projection stereolithography, and the preparation of high-resolution 3D structures without sacrificing bulk material properties. Synthesis of a soluble precursor polymer containing photo-crosslinkable acrylate groups enables light-induced, chemical crosslinking for spatial control in the gel state. Postprinting thermal treatment transforms the crosslinked precursor polymer to PMDA-ODA. The dimensional shrinkage is isotropic, and postprocessing preserves geometric integrity. Furthermore, large-area mask-projection scanning stereolithography demonstrates the scalability of 3D structures. These unique high-performance 3D structures offer potential in fields ranging from water filtration and gas separation to automotive and aerospace technologies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. IMPURITY-FREE MODIFICATION AND NANO-DISPERSION OF CARBON BLACK IN POLYIMIDE FILMS%炭黑的“impurity-free"改性及其在聚酰亚胺薄膜中的分散特性研究

    Institute of Scientific and Technical Information of China (English)

    刘星; 张栋葛; 万月; 吴国章

    2012-01-01

    利用聚酰胺酸(PAA)在研磨过程形成炭黑(CB)的“impurity-free”分散剂制备纳米CB填充聚酰亚胺(PI)高性能复合薄膜.球磨CB和PAA/N-甲基-2-吡咯烷酮(NMP)溶液的混合液,PAA在研磨过程中降解形成活性分子,原位生成与CB表面具有反应活性和强烈物理吸附能力的“impurity-free”分散剂.拉曼、红外以及紫外-可见光吸收光谱证实了降解PAA分子对CB的改性作用.经改性的CB与PAA溶液共混,涂覆固化制备PI/CB复合薄膜.TEM照片表明该分散剂可以显著促进CB粒子在PI基体中的均匀分散,分散粒径约为200nm.力学性能测试和导电性能测试表明PI/CB复合薄膜的断裂伸长率大幅提高,电阻率(ρ)重复性浮动范围从2个数量级降到1个数量级.进一步研究发现,研磨过程中添加高分子量PAA更有利于CB在PI基体中的均匀分散.%Carbon black (CB)-filled polyimide (PI) composites were prepared using self-degradated low molecular poly(amic acid) (PA A) as impurity-free dispersant. CB and PAA/iV-methyl-2-pyrrolidone (NMP) solution were milled in ball miller. The impurity-free dispersant was prepared in the process of in situ degradation of PAA by high-energy milling process,which was active to carbon black (CB) surface. The effect of PAA modification on the CB particles was researched by Raman, IR and UV-Vis. TEM observation showed that the PAA modified CB particles dispersed uniformly in the mixtures with an average CB size of about 200 nm. The toughness, tensile strength and the reproducibility of resistivity for resulted CB/PI composite films were greatly improved. The elongation of resulted CB/PI films was raised at least 50% ,and sample-to-sample variation of elongation was decreased from 17% to 11% . The tensile strength variation range was reduced from 12 MPa to 5 MPa. Resistivity variation range was decreased from two orders down to an order. The molecular weight of PAA added in milling progress played an important

  18. Polyimides derived from non-aromatic monomers

    Energy Technology Data Exchange (ETDEWEB)

    Volksen, W.; Sanchez, M.I.; Cha, Hyuk-Jin; Yoon, D.Y. [IBM Almaden Research Center, San Jose, CA (United States)

    1995-12-01

    In recent years the shift in emphasis on high performance polymers, such as polyimides for microelectronic applications, has led to the search for other potential applications utilizing the unique properties of this class of polymers. In this context, polyimides incorporating non-aromatic units in the polymer backbone have been shown to exhibit excellent optical properties as well as significantly lower refractive indices. This lowering in the refractive index, of course, is also reflected in a lower dielectric constant of the material. For this reason, we have initiated a study of new polyimides, in which the traditional aromatic character is diluted with cycloaliphatic structures. One such example is the polyimide derived from hexafluoroisopropylidene diphthalic anhydride (6FDA) and 1,4-diaminocyclohexane (DACH). Preliminary data with respect to the preparation and solution behavior of the polyimide precursor as well as the characterization of relevant physical properties of the final polyimide will be presented.

  19. Atomic step-and-terrace surface of polyimide sheet for advanced polymer substrate engineering

    Science.gov (United States)

    Tan, G.; Shimada, K.; Nozawa, Y.; Kaneko, S.; Urakami, T.; Koyama, K.; Komura, M.; Matsuda, A.; Yoshimoto, M.

    2016-07-01

    Typical thermostable and flexible polyimide polymers exhibit many excellent properties such as strong mechanical and chemical resistance. However, in contrast to single-crystal substrates like silicon or sapphire, polymers mostly display disordered and rough surfaces, which may result in instability and degradation of the interfaces between thin films and polymer substrates. As a step toward the development of next-generation polymer substrates, we here report single-atom-layer imprinting onto the polyimide sheets, resulting in an ultrasmooth 0.3 nm high atomic step-and-terrace surface on the polyimides. The ultrasmooth polymer substrates are expected to be applied to the fabrication of nanostructures such as superlattices, nanowires, or quantum dots in nanoscale-controlled electronic devices. We fabricate smooth and atomically stepped indium tin oxide transparent conducting oxide thin films on the imprinted polyimide sheets for future use in organic-based optoelectronic devices processed with nanoscale precision. Furthermore, toward 2D polymer substrate nanoengineering, we demonstrate nanoscale letter writing on the atomic step-and-terrace polyimide surface via atomic force microscopy probe scratching.

  20. Thin Films Protect Electronics from Heat and Radiation

    Science.gov (United States)

    2013-01-01

    While Anne St. Clair worked on high performance polyimides at Langley Research Center, she noticed that some of the films were nearly colorless. The polyimides became known as LaRC-CP1 and LaRC-CP2, and were licensed by NeXolve Corporation, based in Huntsville, Alabama. Today, NeXolve provides polyimide film products to commercial customers for spacecraft, telescopes, and circuit boards.

  1. Diffraction filters based on polyimide and poly(ethylene naphthalate) track membranes

    Science.gov (United States)

    Mitrofanov, A. V.; Apel, P. Yu.; Blonskaya, I. V.; Orelovitch, O. L.

    2006-09-01

    The problem of optical filters for soft x rays and extreme ultraviolet that provide a high degree of blocking ultraviolet and visible background radiations is considered. The subject of discussion is the filter based on a track membrane, a polymer film with micrometer and submicrometer pores, rather than the standard thin-film system. It is proposed that the membranes be made of poly(ethylene naphthalate) or polyimide, the UV absorption edge of which lies near the boundary of the visible range. The properties of poly(ethylene naphthalate) and polyimide membranes are contrasted with those of conventional porous poly(ethylene terephthalate) films, which are obtained by ion track etching. The spectral characteristics of poly(ethylene naphthalate) and polyimide films, as well as the formation of “track” pores when the specimens are successively treated by fast ions and chemicals, are studied. The basic parameters of the resulting porous structures are examined, and treatment conditions under which desired optical properties of the membranes are achieved are found. Filters based on poly(ethylene naphthalate) and polyimide track membranes may be applied in x-ray astronomy as constituents of detectors incorporated into solar telescopes and in experiments with the laboratory plasma.

  2. Circuits and AMOLED display with self-aligned a-IGZO TFTs on polyimide foil

    NARCIS (Netherlands)

    Nag, M.; Bhoolokam, A.; Smout, S.; Willegems, M.; Muller, R.; Myny, K.; Schols, S.; Ameys, M.; Genoe, J.; Ke, T.H.; Vicca, P.; Ellis, T.; Cobb, B.; Kumar, A.; Steen, J.L.P.J. van der; Gelinck, G.; Fukui, Y.; Obata, K.; Groeseneken, G.; Heremans, P.; Steudel, S.

    2015-01-01

    A process to make self-aligned top-gate amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) on polyimide foil is presented. The source/drain (S/D) region's parasitic resistance reduced during the SiN interlayer deposition step. The sheet resistivity of S/D region after exposure

  3. Photothermal imaging of damage and undercutting to gold-coated Kapton samples exposed to atomic oxygen

    Science.gov (United States)

    Williams, A. W.; Wood, N. J.

    1996-09-01

    In this paper we describe the design and construction of a laser-based photothermal imaging system, which we have used to evaluate damage to gold-coated Kapton samples that have been exposed to atomic oxygen in a laboratory atomic oxygen source. This exposure simulates the erosive effects of atomic oxygen on spacecraft materials in low Earth orbits. In particular, thermal wave imaging studies have been carried out for materials that are susceptible to atomic oxygen erosion. The photothermal imaging method is sensitive to invisible subsurface features such as the delamination of barrier coatings used to protect vulnerable substrates.

  4. Rationally designed polyimides for high-energy density capacitor applications.

    Science.gov (United States)

    Ma, Rui; Baldwin, Aaron F; Wang, Chenchen; Offenbach, Ido; Cakmak, Mukerrem; Ramprasad, Rampi; Sotzing, Gregory A

    2014-07-01

    Development of new dielectric materials is of great importance for a wide range of applications for modern electronics and electrical power systems. The state-of-the-art polymer dielectric is a biaxially oriented polypropylene (BOPP) film having a maximal energy density of 5 J/cm(3) and a high breakdown field of 700 MV/m, but with a limited dielectric constant (∼2.2) and a reduced breakdown strength above 85 °C. Great effort has been put into exploring other materials to fulfill the demand of continuous miniaturization and improved functionality. In this work, a series of polyimides were investigated as potential polymer materials for this application. Polyimide with high dielectric constants of up to 7.8 that exhibits low dissipation factors (<1%) and high energy density around 15 J/cm(3), which is 3 times that of BOPP, was prepared. Our syntheses were guided by high-throughput density functional theory calculations for rational design in terms of a high dielectric constant and band gap. Correlations of experimental and theoretical results through judicious variations of polyimide structures allowed for a clear demonstration of the relationship between chemical functionalities and dielectric properties.

  5. Microstructure and Thermomechanical Properties of Polyimide-Silica Nanocomposites

    Directory of Open Access Journals (Sweden)

    A. Al Arbash

    2006-01-01

    Full Text Available Novel polyimide-silica nanocomposites with interphase chemical bonding have been prepared using the sol-gel process. The morphology, thermal and mechanical properties were studied as a function of silica content and compared with the similar composites having no interphase interaction. The polyimide precursors, polyamic acids (PAAs with or without pendant hydroxyl groups were prepared from the reaction of pyromellitic dianhydride with a mixture of oxydianiline and 1,3 phenylenediamine or 2,4-diminophenol in dimethylacetamide. The PAA with pendant hydroxyl groups was reacted with isocyanatopropyltriethoxysilane to produce alkoxy groups on the chain. The reinforcement of PAA matrices with or without alkoxy groups on the chain was carried out by mixing appropriate amount of tetraethoxysilane (TEOS and carrying out its hydrolysis and condensation in a sol-gel process. Thin hybrid films were imidized by successive heating up to 300C∘. The presence of alkoxy groups on the polymer chain and their cocondensation with TEOS developed the silica network which was interconnected chemically with the polyimide matrix. SEM studies show a drastic decrease in the silica particle size in the chemically bonded system. Higher thermal stability and mechanical strength, improved transparency, and low values of thermal coefficient of expansion were observed in case of chemically bonded composites.

  6. Preparation and Study of Dielectric Property of Polyimide Films Hybrided with Nano Silica-alumina Oxide%纳米硅/铝氧化物杂化聚酰亚胺薄膜的制备与电性能研究

    Institute of Scientific and Technical Information of China (English)

    梁凤芝; 陈磊; 陈昊; 范勇

    2011-01-01

    A nano-alumina sol was synthesized by hydrothermal process and a silica sol was prepared by sol-gel method, then they were doped into polyamic acid matrix. A series of inorganic nano-hybrid polyimide films were prepared by adjusting the molar ratio of nano-silicon/ aluminum oxides whose total content is 24%. The structure and properties of the films were characterized by SEM and measured by corona discharge measuring equipment and breakdown strength measuring system respectively. The results show that inorganic nano particles are well dispersed in the polyimide matrix when a little amount of silica sol is doped; the corona-resistant time of hybrid films is much longer than that of pure film and when the molar ratio of nano-silicon/ aluminum oxides is 1:13, the corona-resistant time reaches up to 62.15h; When increasing the doping amount of silica sol, the breakdown strength of the doped films first decreases and then increases, but is lower than that of the undoped film.%采用水热法制备纳米氧化铝溶胶,溶胶-凝胶法制备氧化硅溶胶,并将两者掺杂到聚酰亚胺(PI)基体中.实验中固定无机物掺杂总量为24%,通过调整纳米硅/铝氧化物的摩尔比,制备出一系列的无机纳米杂化聚酰亚胺薄膜.利用扫描电子显微镜(SEM)、耐电晕测试装置、耐击穿测试装置对薄膜进行了表征与测试.结果表明:硅溶胶掺杂量较小时,纳米粒子能较好地分散在聚酰亚胺基体中;杂化薄膜的耐电晕时间比纯膜有较大幅度提高,硅/铝摩尔比为1:13时,耐电晕时间达到62.15 h;随着硅溶胶掺杂量的增加,杂化薄膜的击穿强度先减小后增大,但均比纯膜的低.

  7. Positronium formation in various polyimides

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Ken-ichi; Tanaka, Kazuhiro; Katsube, Mikio; Sueoka, Osamu; Ito, Yasuo (Yamaguchi Univ., Ube (Japan). Faculty of Engineering Tokyo Univ. (Japan). Research Center for Nuclear Science and Technology)

    1993-03-01

    Positronium (Ps) formation in various polyimides has been studied. It has been found that Ps yield is zero or small in the polyimides having pyromellitic dianhydride (PMDA) and 3,3[sup '],4,4[sup ']-benzophenonetetracarboxylic dianhydride (BTDA) as acid anhydride moiety, while those having 3,3[sup '],4,4[sup ']-biphenyltetracarboxylic dianhydride (BPDA) and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) form Ps with intensities up to about 20%. This difference is well correlated with the electron affinity of these moieties: PMDA > BTDA > BPDA [approx] 6FDA. In another experiment o-Ps yields and its lifetimes were measured in benzene solutions of monomeric model compounds (imide compounds prepared from n-butylamine and the acid anhydrides). It has been found that the model compounds from PMDA and BTDA both inhibit Ps formation and quench o-Ps lifetimes but that those from BPDA and 6FDA have neither the inhibition nor the quenching effects. The results show that the spur model is applicable for Ps formation in the polyimides. (Author).

  8. Positronium formation in various polyimides

    Science.gov (United States)

    Okamoto, Ken-ichi; Tanaka, Kazuhiro; Katsube, Mikio; Sueoka, Osamu; Ito, Yasuo

    1993-03-01

    Positronium (Ps) formation in various polyimides has been studied. It has been found that Ps yield is zero or small in the polyimides having pyromellitic dianhydride (PMDA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) as acid anhydride moiety, while those having 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 2,2- bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) form Ps with intensities up to about 20%. This difference is well correlated with the electron affinity of these moieties: PMDA > BTDA > BPDA ˜ 6FDA. In another experiment o-Ps yields and its lifetimes were measured in benzene solutions of monomeric model compounds (imide compounds prepared from n-butylamine and the acid anhydrides). It has been found that the model compounds from PMDA and BTDA both inhibit Ps formation and quench o-Ps lifetimes but that those from BPDA and 6FDA have neither the inhibition nor the quenching effects. The results show that the spur model is applicable for Ps formation in the polyimides.

  9. Photoluminescence and Exciton Energy Transfer of A Novel Perylene-Containing Polyimide

    Institute of Scientific and Technical Information of China (English)

    Shengang Xu; Mujie Yang; Shaokui Cao

    2005-01-01

    @@ 1Introduction Peryleneimides are well known chromophores combining high quantum yields of photoluminescence with outstanding photochemical and thermal stability. Due to their useful electroactive and photoactive properties many potential applications in optoelectronics have attracted increasing interest.Previously, we reported a kind of diphenylfluorene-based cardo polyimide containing perylene units in the backbone[1,2], which possessed high thermal stability, excellent solubility and good film formability. In the present work, the photoluminescence and exciton energy transfer of this novel polyimide were reported.

  10. Flexible Substrates with Polyimide Buffer Layers for Organic Light-Emitting Diodes

    Institute of Scientific and Technical Information of China (English)

    常春; 王立铎; 李扬; 段炼; 邱勇

    2004-01-01

    We report a new method to enhance the properties of the polyethyleneterephthalate (PET) substrates for flexible organic light-emitting diodes (OLEDs). By spin-coating a polyimide (PI) film between the PET and the indiumtin-oxide anode, the flexible substrate with a smooth surface, high transmission over the visible spectrum and good adhesion are achieved. We also compare the flexible OLEDs on different substrates. The diodes on the substrates with polyimide buffer layers exhibit a brightness of 7280cd/m2 at 15 V and the maximum efficiency of 2.64 cd/A.

  11. Application of NiMoNb adhesion layer on plasma-treated polyimide substrate for flexible electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Bang, S.-H.; Kim, K.-K.; Jung, H.-Y.; Kim, T.-H.; Jeon, S.-H. [Metal and Material Technology Group, R and D Center, LS Mtron Ltd., Gyeonggi 431-080 (Korea, Republic of); Seol, Jae-Bok, E-mail: zptkfm20@hanmail.net [Max-Planck-Insititut für Eisenforschung, Max-Planck-Str. 1, D-40237 Düsseldorf (Germany)

    2014-05-02

    A thin film, NiMoNb, was introduced as an adhesion layer between the Cu metal and the insulator polyimide substrate in a flexible Cu-clad laminated structure. Using 90° peel test, we evaluated the peel strength of the system as a function of the thickness of the adhesion layer. An increase in the NiMoNb thickness from 7 to 40 nm enhanced the peel strength of the deposited systems. After plasma treatment by the roll-to-roll method, the multilayer structure showed an outstanding peel strength of ∼ 529 N/m, even after thermal annealing at 150 °C for 168 h. We also studied the role of plasma treatment of the polyimide substrate on the adhesion strength and microstructure of a flexible Cu-clad laminated structure by peel strength, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. These experimental observations showed that the plasma-treated polyimide substrate with the deposition of NiMoNb showed the enhanced adhesion of ∼ 656 N/m, because of the change of functional groups, which affected the bonding force and crystallinity of the thin films deposited on polyimide, rather than an increase in the surface roughness. - Highlights: • NiMoNb film on polyimide substrate was employed for higher peel strength. • Plasma-treated substrate enhances the peel strength of multilayer. • Even when annealed at 150 °C, plasma-treated films showed enhanced peel strength.

  12. Magnetism of FePt Nanoclusters in Polyimide

    Directory of Open Access Journals (Sweden)

    Mircea Chipara

    2015-01-01

    Full Text Available FePt nanoclusters have been implanted onto polyimide films and subjected to thermal annealing in order to obtain a special magnetic phase (L10 dispersed within the polymer. SQUID measurements quantified the magnetic features of the as-prepared and annealed hybrid films. As-implanted FePt nanoparticles in polyimide films exhibited a blocking temperature of 70 ± 5 K. Thermal annealing in zero and 10 kOe applied magnetic field increased the magnetic anisotropy and coercivity of the samples. Wide Angle X-Ray Scattering confirmed the presence of FePt and L10 phase. All samples (as deposited and annealed exhibited electron spin resonance spectra consisting of two overlapping lines. The broad line was a ferromagnetic resonance originating from FePt nanoparticles. Its angular dependence indicated the magnetic anisotropy of FePt nanoparticles. SEM micrographs suggest a negligible coalescence of FePt nanoparticles, supporting that the enhancement of the magnetic properties is a consequence of the improvement of the L10 structure. The narrow ESR line was assigned to nonmagnetic (paramagnetic impurities within the samples consistent with graphite-like structures generated by the local degradation of the polymer during implantation and annealing. Raman spectroscopy confirmed the formation of graphitic structures in annealed KHN and in KHN-FePt.

  13. Dielectric Properties of Polyvinyl Alcohol, Poly(methyl Methacrylate), Polyvinyl Butyral Resin and Polyimide at Low Temperatures

    Science.gov (United States)

    Tuncer, Enis; Sauers, Isidor; James, D. Randy; Ellis, Alvin R.

    2008-03-01

    Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI-Kapton®). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45 K to 350 K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and PMMA dissolved in toluene have the lowest dielectric losses for temperatures lower than 100 K. PVB and PI have the smallest spread in their breakdown strength data.

  14. DIELECTRIC PROPERTIES OF POLYVINYL ALCOHOL, POLY(METHYL METHACRYLATE), POLYVINYL BUTYRAL RESIN AND POLYIMIDE AT LOW TEMPERATURES

    Energy Technology Data Exchange (ETDEWEB)

    Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL

    2008-01-01

    Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI--Kapton\\textregistered). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45K to 350K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and \\pmma\\ dissolved in toluene have the lowest dielectric losses for temperatures lower than $100\\ \\kelvin$. \\Blx\\ and PI have the smallest spread in their breakdown strength data.

  15. Polyimide analysis using diffuse reflectance-FTIR. [Fourier Transform IR Spectroscopy

    Science.gov (United States)

    Young, P. R.; Chang, A. C.

    1985-01-01

    The thermal imidization of a number of polyimide precursors in the form of powders, films, and prepregs was examined by an in situ diffuse reflectance-FTIR technique where infrared spectra were determined while the material was being heated. An analysis of these spectra revealed that, with the exception of one water soluble adhesive, each precursor developed an anhydride band around 1850 cm/cu during imidization. This band diminished in intensity during final stages of cure. Efforts were made to quantify the amount of anhydride in several samples. Evidence obtained could be interpreted to mean that poly(amic acid) resins undergo an initial reduction in molecular weight during imidization before recombining to achieve their ultimate molecular weights as polyimides. Several reports in the literature are cited to support this interpretation. This report serves both to document anhydride formation during imidization and to increase our fundamental understanding of how polyimides cure.

  16. Investigation on the radiation induced conductivity of space-applied polyimide under cyclic electron irradiation

    Science.gov (United States)

    Yue, Long; Wu, Yiyong; Sun, Chengyue; Xiao, Jingdong; Shi, Yaping; Ma, Guoliang; He, Shiyu

    2012-11-01

    Radiation induced conductivity (RIC) is an important property of dielectric materials to evaluate the charge/discharge effect in orbit-service spacecraft. RIC of space-applied polyimide film was in situ measured and studied under continuous and cyclic electron irradiation in this paper. The results indicate that, for cyclic electron irradiation, there is a similar increasing-mode of RIC to those for continuous irradiation with the electron irradiation time. However, under the cyclic electron irradiation, the RIC of polyimide shows an obvious irradiation-history characteristic, namely preliminary irradiation dose effect (PIDE). In this case, the steady RIC value presents an "overshoot" behavior in the first few irradiation cycles and then decrease to a stable one as that under continuous irradiation. Prolonging the initial irradiation duration may avoid occurrence of overshoot phenomenon. The behaviors of irradiation-induced free radicals in polyimide could be applied to explain the RIC evolution processes.

  17. Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane

    Directory of Open Access Journals (Sweden)

    Diego Guzmán-Lucero

    2015-04-01

    Full Text Available A series of new organic polyimides were synthesized from 4-fluoro-4'4"-diaminotriphenylmethane and four different aromatic dianhydrides through a one-step, high-temperature, direct polycondensation in m-cresol at 180–200 °C, resulting in the formation of high-molecular-weight polyimides (inherent viscosities ~ 1.0–1.3 dL/g. All the resulting polyimides exhibited good thermal stability with initial decomposition temperatures above 434 °C, glass-transition temperatures between 285 and 316 °C, and good solubility in polar aprotic solvents. Wide-angle X-ray scattering data indicated that the polyimides were amorphous. Dense membranes were prepared by solution casting and solvent evaporation to evaluate their gas transport properties (permeability, diffusivity, and solubility coefficients toward pure hydrogen, helium, oxygen, nitrogen, methane, and carbon dioxide gases. In general, the gas permeability was increased as both the fractional free volume and d-spacing were also increased. A good combination of permeability and selectivity was promoted efficiently by the bulky hexafluoroisopropylidene and 4-fluoro-phenyl groups introduced into the polyimides. The results indicate that the gas transport properties of these films depend on both the structure of the anhydride moiety, which controls the intrinsic intramolecular rigidity, and the 4-fluoro-phenyl pendant group, which disrupts the intermolecular packing.

  18. Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane

    Science.gov (United States)

    Guzmán-Lucero, Diego; Froylán Palomeque-Santiago, Jorge; Camacho-Zúñiga, Claudia; Ruiz-Treviño, Francisco Alberto; Guzmán, Javier; Galicia-Aguilar, Alberto; Aguilar-Lugo, Carla

    2015-01-01

    A series of new organic polyimides were synthesized from 4-fluoro-4'4"-diaminotriphenylmethane and four different aromatic dianhydrides through a one-step, high-temperature, direct polycondensation in m-cresol at 180–200 °C, resulting in the formation of high-molecular-weight polyimides (inherent viscosities ~ 1.0–1.3 dL/g). All the resulting polyimides exhibited good thermal stability with initial decomposition temperatures above 434 °C, glass-transition temperatures between 285 and 316 °C, and good solubility in polar aprotic solvents. Wide-angle X-ray scattering data indicated that the polyimides were amorphous. Dense membranes were prepared by solution casting and solvent evaporation to evaluate their gas transport properties (permeability, diffusivity, and solubility coefficients) toward pure hydrogen, helium, oxygen, nitrogen, methane, and carbon dioxide gases. In general, the gas permeability was increased as both the fractional free volume and d-spacing were also increased. A good combination of permeability and selectivity was promoted efficiently by the bulky hexafluoroisopropylidene and 4-fluoro-phenyl groups introduced into the polyimides. The results indicate that the gas transport properties of these films depend on both the structure of the anhydride moiety, which controls the intrinsic intramolecular rigidity, and the 4-fluoro-phenyl pendant group, which disrupts the intermolecular packing. PMID:28788041

  19. PMR polyimide composites for aerospace applications. [Polymerization of Monomer Reactants

    Science.gov (United States)

    Serafini, T. T.

    1984-01-01

    A novel class of addition-type polyimides has been developed in response to the need for high temperature polymers with improved processability. The new plastic materials are known as PMR (for in situ polymerization of monomer reactants) polyimides. The highly processable PMR polyimides have made it possible to realize much of the potential of high temperature resistant polymers. Monomer reactant combinations for several PMR polyimides have been identified. The present investigation is concerned with a review of the current status of PMR polyimides. Attention is given to details of PMR polyimide chemistry, the processing of composites and their properties, and aerospace applications of PMR-15 polyimide composites.

  20. A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser

    OpenAIRE

    Tianxian Feng; Dong Mao; Xiaoqi Cui; Mingkun Li; Kun Song; Biqiang Jiang; Hua Lu; Wangmin Quan

    2016-01-01

    We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP) nanosheets were prepared via a liquid exfoliation approach exploiting N-methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI), a piece of BP–PI film was obtained after evaporating the mixture in a petri dish. The BP–PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser...

  1. Stopping power of 1.0-3.0 MeV helium in Mylar, Makrofol and Kapton foils

    CERN Document Server

    Chekirine, M

    1999-01-01

    The stopping powers of 1.0-3.0 MeV of helium ( sup 4 He) in Makrofol KG, Mylar and Kapton were measured. The results were compared with scanty experimental data in the literature and with values predicted by both Bragg's rule and cores-and-bonds model. These values agree with each other within the uncertainties; maximum deviations are <5%.

  2. Surface characteristics and adhesive strengths of metal on O{sub 2} ion beam treated polyimide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung C. [Department of Polymer Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746 (Korea, Republic of)], E-mail: skkscpark@skku.edu; Yoon, Seong S.; Nam, J.D. [Department of Polymer Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2008-03-31

    A polyimide surface was modified by oxygen ion beam bombardment to improve its adhesion to a subsequently deposited NiCr (nickel-chromium alloy) overlayer. The changes in the chemical composition, morphology and adhesion property of the modified polyimide surface were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and the 90{sup o} peel test. The results show that the oxygen ion beam treatment of the polyimide induces the formation of oxygen functional groups and the rearrangement of the imide groups in the polyimide substrate film. An increase in its surface roughness resulted in a substantial improvement in the adhesion strength between the polyimide and NiCr overlayer. The improved adhesion strength, however, was found to be reduced after thermal aging at 150 deg. C for 168 hrs, which was attributed to the thermal oxidative degradation of the polyimide at the interface. We also observed that the ion beam treatment was effective in retarding the adhesion loss caused by the thermal aging.

  3. SiO2表面包覆改性钛酸钡/聚酰亚胺复合薄膜的制备与性能∗%Preparation and dielectric property of SiO2 surface coating modified BaTiO3/polyimide composite film

    Institute of Scientific and Technical Information of China (English)

    王亚军; 武晓娟; 冯长根; 曾庆轩

    2015-01-01

    以聚酰亚胺(PI)为基体,将聚酰亚胺与钛酸钡(BaTiO3)纳米粒子进行复合,采用原位聚合法制备BaTiO3/PI复合薄膜.为提高 BaTiO3纳米粒子的分散性和表面性能,采用 SiO2对 BaTiO3纳米粒子进行表面包覆改性,并制备改性 BaTiO3/PI 复合薄膜.采用红外光谱、X射线衍射、扫描电镜等对制备得到的改性BaTiO3进行了表征,测试了复合薄膜的介电性能.结果发现,SiO2与BaTiO3粒子间仅是物理包覆,没有新物质形成.测试频率为103 Hz 时,质量分数为5%的SiO2包覆改性使复合薄膜的介电常数增大到21.8,介电损耗为0.00521,击穿强度为76 MV/m,储能密度为0.56 J/cm3.研究表明,采用 SiO2对 BaTiO3改性使得复合薄膜的介电性能有所提高.%Polyimide (PI)was chosen as the matrix of the composite,barium titanate/polyimide (BaTiO3/PI) nanocomposite films were prepared with in situ polymerization.In order to improve the dispersion and the phys-ical-chemical properties of BT surface,barium titanate was modified by SiO2 coating and modified barium titan-ate/polyimide (BaTiO3/PI)nanocomposite films were prepared.The prepared modified BaTiO3 was character-ized by X-ray diffraction (XRD)analysis,Fourier transform infrared spectroscopy (FT-IR)and scanning elec-tron microscopy (SEM),and the dielectric properties of the composites were characterized in detail.It was shown that surface modification with SiO2 was the physical effect and there were no new substances forming. When BaTiO3 was modified by 5% SiO2 ,the dielectric constant of the composite film was 21.8 (103 Hz),the loss tangent 0.00521,breakdown strength 76 MV/m,energy storage density 0.56 J/cm3 .The BaTiO3 surface coating modification by SiO2 was beneficial to the dielectric properties of the BaTiO3/PI composite film.

  4. New polyimide-polyoxometalate nanocomposite materials with nanoporous structure and ultra-low dielectric constant, formed in supercritical carbon dioxide

    Science.gov (United States)

    Keshtov, Mukhamed; Said-Galiev, Ernest; Kochurov, Vitaliy; Khokhlov, Alexei

    2012-07-01

    Vinyltrimethoxysilane interaction with K8(SiW11O39) obtained polyoxometalate (Bu4N)4[SiW11O39{(CH2 = CH-Si)2O}](SiW11-CH = CH2). Synthesized two new fluorinated aromatic polyimide in two stages with a dielectric constant (k) in the range 2.70-2.75. On the basis of poly(amic acids) and a mixture of thermal imidization polyoxometalate obtained polyimide/polyoxometalate composite film. It was found that with increasing polyoxometalate in a mixture of 0 to 20 wt% the dielectric constant decreases from 2,75 to 1,70. Nanoporous materials with ultra-low dielectric constant in the range 1.31-1.64 in combination with high thermal (T10% = 536-570°C in N2) and mechanical characteristics using supercritical carbon dioxide have been developed on the basis of the obtained polyimide/polyoxometalate composite films.

  5. Ion beam modification of polyimide membranes for gas permeation

    Science.gov (United States)

    Escoubes, M.; Dolveck, J. Y.; Davenas, J.; Xu, X. L.; Boiteux, G.

    1995-11-01

    The irradiation of 6FDA (hexafluorodianhydrid) polyimide films, produced for gas separation, with ion beams leads to dramatic modifications of their permeability to hydrogen and methane. The irradiation of the PI membranes with 2 MeV α particles induces a permeability increase for both gases, whereas a reduction of the permeability to CH 4 is obtained for a bombardment of the films with 170 keV N + at fluences larger than 10 15 cm -2. The modification of the diffusion through the membranes has been interpreted using a multilayer model, which enabled the calculation of the intrinsic permeabilities of the irradiated layers. The second irradiation regime induces a significant selectivity enhancement. The improvement of the selective properties of the irradiated membranes is interpreted in terms of modification of the elementary free volumes involving the reduction of the mean size.

  6. Low toxicity high temperature PMR polyimide

    Science.gov (United States)

    Pater, Ruth H. (Inventor)

    1992-01-01

    In-situ polymerization of monomer reactants (PMR) type polyimides constitute an important class of ultra high performance composite matrix resins. PMR-15 is the best known and most widely used PMR polyimide. An object of the present invention is to provide a substantially improved high temperature PMR-15 system that exhibits better processability, toughness, and thermo-oxidative stability than PMR-15, as well as having a low toxicity. Another object is to provide new PMR polyimides that are useful as adhesives, moldings, and composite matrices. By the present invention, a new PMR polyimide comprises a mixture of the following compounds: 3,4'-oxydianiline (3,4'-ODA), NE, and BTDE which are then treated with heat. This PMR was designated LaRC-RP46 and has a broader processing window, better reproducibility of high quality composite parts, better elevated temperature mechanical properties, and higher retention of mechanical properties at an elevated temperature, particularly, at 371 C.

  7. Prediction of the response of a polyimide concentrator for solar thermal propulsion

    Science.gov (United States)

    Gierow, Paul Armin; Moore, James D.

    1993-11-01

    Solar Thermal propulsion requires the use of large solar collectors to focus solar energy into an absorber which heats a propellant gas that is expanded through a nozzle creating thrust. The solar thermal rocket offers specific heat impulse (Isp) on the order of 900-1000 seconds at moderate thrust levels for orbiter transfer vehicles. These Isp and thrust levels are contingent on proper design, fabrication and operation of large solar collectors. Thin film polyimide materials developed by NASA Langley Research Center (LaRC) have been used to construct large inflatable concentrators for space deployable collectors. Concentrators of sizes up to five meters in diameter have been cast and cured in the laboratory with a 0.0254mm (0.001 in) film thickness. The films are cast on double curvature mandrels in solution form and cured, resulting in a large one piece parabolic concentrator without seams. The polyimide films do not exhibit orthotropic material properties when fabricated using these processes. An analytical model of a uniformly loaded parabolic membrane was developed to predict the deflection of the membrane under prescribed loading conditions and varying material properties. A symmetrical parabolic and off-axis geometry concentrator have been modeled. The analytical model uses finite element analysis of a membrane material under a variety of stress conditions. Prediction of the deformations of the membrane as a result of material properties and loading conditions is required to select and develop appropriate polyimide materials. The predicted membrane deflections are also integrated into an optical ray trace program to estimate the solar flux distribution at the focal point of the primary collector. The edge effects of inflatable concentrators can greatly affect the flux distribution at the focal plane of the concentrator. The overall concentration ratio of a primary collector directly relates to the achievable working fluid temperatures. This paper will

  8. Influence of Steric Hindrance Between Hydrogen Atoms of Linkage Groups and Adjacent Phenyls on Properties of Polyimide

    Institute of Scientific and Technical Information of China (English)

    PANG Yu-wei; LUO Long-bo; CHEN Yi; ZHANG Peng; WANG Xu; PENG Chao-rong; LIU Xiang-yang

    2012-01-01

    A diamine monomer 4,4'-methylenedianiline(MDA) was introduced to modify the polyimide of pyromellitic dianhydride(PMDA) and 4,4'-oxydianiline(ODA) by polycondensation.A series of polyamic acids was synthesized from MDA and ODA of different molar ratios with PMDA of sum mole of moles of MDA and ODA,and polyimide films were obtained by thermal imidization.Polyimide(PI) films were characterized by tensile testing,dynamic mechanical analysis(DMA),thermal gravimetry analysis(TGA),Fourier transform infrared spectroscopy (FTIR),wide X-ray diffraction(WAXD) and molecular simulation.With the increase of MDA content,the tensile strength and thermal decomposition temperature remained generally stable compared with those of PMDA/ODA polyimide.Unexpectedly,the glass transition temperature(Tg) and Young's modulus increased from 388.7 ℃ and 2.37 GPa to 408.3 ℃ and 5.74 GPa,respectively.The results of WAXD and molecular simulation indicate the steric hindrance among hydrogen atoms of the linkage groups and adjacent phenyls enhanced the properties of the polyimide modified with MDA.

  9. Fabrication of polyimide micro/nano-structures based on contact-transfer and mask-embedded lithography

    Science.gov (United States)

    Chiu, Cheng-Yu; Lee, Yung-Chun

    2009-10-01

    Polyimide materials are well known for their excellent mechanical and chemical stability which, as an adverse consequence, makes their fabrication processes much more difficult, especially in micro- and nano-scales. In this paper, we demonstrate an innovative and powerful method for fabricating micro/nano-structures on polyimides. The proposed method first adopts an imprinting approach to transfer a patterned metal film from a mold to a polymer layer coated on a polyimide layer. The patterned double polymer layers are then dry etched using the transferred metal pattern as an etching mask. Finally, polyimide structures are obtained by lifting off the top polymer layer and the metal film through wet etching. Experiments have been carried out and important parameters to achieve high pattern-transformation fidelity are determined. Fine structures of polyimides with a feature size of 500 nm and a total patterned area of 8 × 8 mm2 are demonstrated. Advantages of the proposed method include low-temperature, low contact pressure, small feature size, high throughput and ease of in implementation. Most importantly, it is applicable for a large number of tough polymers which are difficult to deal with by other methods in terms of micro/nano-fabrication.

  10. 柔性光学聚酰亚胺薄膜折射率均匀性检测方法%Refractive Index Homogeneity Measure Method of Flexible Optical Polyimide Film

    Institute of Scientific and Technical Information of China (English)

    王松; 杨伟; 吴时彬; 任戈

    2016-01-01

    Aiming at refractive index homogeneity of space flexible optical polyimide membrane, it can be measured through reflected wavefront of the substrate for preparation of polyimide optical membrane, reflected wavefront of up-surface of the membrane before being released from substrate and the transmission wavefront after the membrane released from substrate. Compared with data measured by the prism coupling, the results show that the proposed method is efficient and reliable for refractive index homogeneity measurement of flexible membrane in fully-aperture.%针对空间应用的柔性光学聚酰亚胺薄膜折射率均匀性检测要求,本文提出以干涉测量法为基础,采用光学聚酰亚胺薄膜制备所用基板的反射波前数据、薄膜未剥离成膜基板时上表面反射波前数据以及薄膜剥离基板后的透射波前数据有效测量此类柔性薄膜折射率均匀性。将棱镜耦合仪逐点测量数据作为对比项,实验结果表明,所提出的方法能高效可靠地对柔性薄膜全口径进行折射率均匀性检测。

  11. Adhesion measurement of a buried Cr interlayer on polyimide

    Science.gov (United States)

    Marx, Vera M.; Kirchlechner, Christoph; Zizak, Ivo; Cordill, Megan J.; Dehm, Gerhard

    2015-06-01

    A fundamental knowledge and understanding of the adhesion behaviour of metal-polymer systems is important as interface failure leads to a complete breakdown of flexible devices. A combination of in situ atomic force microscopy for studying topological changes and in situ synchrotron based stress measurements both during film tensile testing were used to estimate the adhesion energy of a thin bilayer film. The film systems consisted of 50-200 nm Cu with a 10 nm Cr adhesion layer on 50 μm thick polyimide. If the Cu film thickness is decreased to 50 nm the Cr interlayer starts dominating the system behaviour. An apparent transition from plastic to predominantly brittle deformation behaviour of the Cu can be observed. Then, compressive stresses in the transverse direction are high enough to cause delamination and buckling of the Cr interlayer from the substrate. This opens a new route to induce buckling of a brittle interlayer between a ductile film and a compliant substrate which is used to determine the interfacial adhesion energy.

  12. Novel thin film polymer foaming technique for low and ultra low-k dielectrics

    NARCIS (Netherlands)

    Krause, B.; Koops, G.H.; Vegt, van der N.F.A.; Wessling, M.; Wubbenhorst, M.; Turnhout, van J.

    2001-01-01

    The results presented show a novel route for the preparation of thin ultra-low-k polymer films based on commercial and "non-exotic" (non-expensive) polyimide by a foaming technique. Dependent on the glass transition temperature of the polyimide mechanically and thermally stable (> 300 °C) films havi

  13. Dianhydrides, polyimides, methods of making each, and methods of use

    KAUST Repository

    Ma, Xiaohua

    2015-01-08

    Embodiments of the present disclosure provide for an aromatic dianhydride, a method of making an aromatic dianhydride, an aromatic dianhydride-based polyimide, a method of making an aromatic dianhydride-based polyimide, and the like.

  14. SYNTHESIS AND CHARACTERIZATION OF HIGHLY SOLUBLE AROMATIC POLYIMIDES

    Institute of Scientific and Technical Information of China (English)

    Xiao-hua Huang; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    Two highly soluble aromatic polyimides were synthesized successfully from a diamine with two tert-butyl groups (MBTBA) and dianhydrides with a thioether or sulfone moiety (DTDA and DSDA). Both of them showed excellent solubility in common solvents such as chloroform, tetrahydrofuran and dioxane at the room temperature. The numberaverage molecular weight was 6.0 × 104 and 8.3 × 104 according to gel permeation chromatography relative to a polystyrene standard, and the polydispersity index was 1.80 and 1.82 respectively. The glass-transition temperatures of them were 286℃and 314℃ (or 315℃ and 358℃) respectively, as measured by differential scanning calorimetry (or dynamic mechanical analysis). The 5% weight loss temperature of both was near 490℃ in N2 by thermogravimetric analysis. These results indicated that the tert-butyl pendent groups reduced the interactions among polymer chains and the thioether or sulfone moiety was flexible which may improve their solubility in conventional organic solvents without the loss of thermal stability.Transparent and flexible films of the two polyimides were obtained via solution casting. The MBTBA-DTDA membrane had higher storage moduli than those of the MBTBA-DSDA membrane.

  15. Porous Cross-Linked Polyimide-Urea Networks

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor); Nguyen, Baochau N. (Inventor)

    2015-01-01

    Porous cross-linked polyimide-urea networks are provided. The networks comprise a subunit comprising two anhydride end-capped polyamic acid oligomers in direct connection via a urea linkage. The oligomers (a) each comprise a repeating unit of a dianhydride and a diamine and a terminal anhydride group and (b) are formulated with 2 to 15 of the repeating units. The subunit was formed by reaction of the diamine and a diisocyanate to form a diamine-urea linkage-diamine group, followed by reaction of the diamine-urea linkage-diamine group with the dianhydride and the diamine to form the subunit. The subunit has been cross-linked via a cross-linking agent, comprising three or more amine groups, at a balanced stoichiometry of the amine groups to the terminal anhydride groups. The subunit has been chemically imidized to yield the porous cross-linked polyimide-urea network. Also provided are wet gels, aerogels, and thin films comprising the networks, and methods of making the networks.

  16. Reflectance measurements of PTFE, Kapton, and PEEK for xenon scintillation light for the LZ detector.

    Science.gov (United States)

    Arthurs, M.; Batista, E.; Haefner, J.; Lorenzon, W.; Morton, D.; Neff, A.; Okunawo, M.; Pushkin, K.; Sander, A.; Stephenson, S.; Wang, Y.; LZ Collaboration

    2017-01-01

    LZ (LUX-Zeplin) is an international collaboration that will look for dark matter candidates, WIMPs (Weakly Interacting Massive Particles), through direct detection by dual-phase time projection chamber (TPC) using liquid xenon. The LZ detector will be located nearly a mile underground at SURF, South Dakota, shielded from cosmic background radiation. Seven tons active mass of liquid xenon will be used for detecting the weak interaction of WIMPs with ordinary matter. Over three years of operation it is expected to reach the ultimate sensitivity of 2x10-48 cm2 for a WIMP mass of 50 GeV. As for many other rare event searches, high light collection efficiency is essential for LZ detector. Moreover, in order to achieve greater active volume for detection as well as reduce potential backgrounds, thinner detector walls without significant loss in reflectance are desired. Reflectance measurements of polytetrafluoroethylene (PTFE), Kapton, and PEEK for xenon scintillation light (178 nm), conducted at the University of Michigan using the Michigan Xenon Detector (MiX) will be presented. The University of Michigan, LZ Collaboration, The US Department of Energy.

  17. Synthesis and Characterization of Poly(maleic Anhydride)s Cross-linked Polyimide Aerogels

    Science.gov (United States)

    Guo, Haiquan; Meador, Mary Ann B.

    2015-01-01

    With the development of technology for aerospace applications, new thermal insulation materials are required to be flexible and capable of surviving high heat flux. For instance, flexible insulation is needed for inflatable aerodynamic decelerators which are used to slow spacecraft for entry, descent and landing (EDL) operations. Polyimide aerogels have low density, high porosity, high surface area, and better mechanical properties than silica aerogels and can be made into flexible thin films, thus they are potential candidates for aerospace needs. The previously reported cross-linkers such as octa(aminophenyl)silsesquioxane (OAPS) and 1,3,5-triaminophenoxybenzene (TAB) are either expensive or not commercially available. Here, we report the synthesis of a series of polyimide aerogels cross-linked using various commercially available poly(maleic anhydride)s, as seen in Figure 1. The amine end capped polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA) and diamine combinations of dimethylbenzidine (DMBZ) and 4, 4-oxydianiline (ODA). The resulting aerogels have low density (0.12 gcm3 to 0.16 gcm3), high porosity (90) and high surface area (380-554 m2g). The effect of the different poly(maleic anhydride) cross-linkers and polyimide backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed.

  18. Synthesis and characterization of new polyimide/organo clay nano composites containing benzophenone moieties in the main chain

    Energy Technology Data Exchange (ETDEWEB)

    Faghihi, K.; Ashouri, M.; Feyzi, A., E-mail: k-faghihi@araku.ac.ir [Arak University, Faculty of Science, Organic Polymer Chemistry Research Laboratory, 38158-879 Arak (Iran, Islamic Republic of)

    2013-08-01

    A series of nano composites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt %, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nano composite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane and 3,3,4,4-benzophenone tetra carboxylic dianhydride in N,N-dimethylacetamide (Dmac). The resulting nano composite films were characterized by Ft-IR spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. (Author)

  19. Coupling Between Microstrip Lines with Finite Width Ground Plane Embedded in Polyimide Layers for 3D-MMICs on Si

    Science.gov (United States)

    Ponchak, George E.; Dalton, Edan; Tentzeris, Emmanouil M.; Papapolymerou, John; Williams, W. Dan (Technical Monitor)

    2001-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/millimeter-wave integrated circuits on complementary metal oxide semiconductor (CMOS) (low resistivity) Si wafers. Thin film microstrip lines (TFMS) with finite width ground planes embedded in the polyimide are often used. However, the closely spaced TFMS lines are susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and experimental measurements are used to show that the ground planes must be connected by via holes to reduce coupling in both the forward and backward directions.

  20. Novel organosoluble polyimide based on an asymmetric bis(ether amine): 3, 4'-Bis(4-aminophenoxy)-benzophenone

    Institute of Scientific and Technical Information of China (English)

    Qian Qian Bu; Shu Jiang Zhang; Hui Li; Yan Feng Li

    2012-01-01

    A new kind of asymmetrical ether diamine,3,4'-bis(4-aminophenoxy)benzophenone (BABP),was synthesized from the nucleophilic substitution reaction of 4-chloronitrobenzene and 3,4'-dihydroxybenzophenone in the presence of potassium carbonate,followed by catalytic reduction with SnCl2-6H2O and concentrated hydrochloric acid.The prepared diamine was employed in the preparation of a novel polyimide containing asymmetrical diaryl ether segments via the polycondensation of it with BTDA by a two-step method.The resulting polyimide exhibits excellent solubility,film-forming capability and high thermal resistance.

  1. ORGANO-SOLUBLE FLUORINATED POLYIMIDES DERIVED FROM α,α-BIS(4-AMINO-3,5- DIMETHYLPHENYL)-4'-FLUOROPHENYL METHANE AND VARIOUS AROMATIC DIANHYDRIDES

    Institute of Scientific and Technical Information of China (English)

    Jin-gang Liu; Yang-xi Peng; Hong-shen Li; Lin Fan; Shi-yong Yang

    2005-01-01

    Organo-soluble fluorinated polyimides were synthesized by the polycondensation of a new aromatic diamine α,αbis(4-amino-3,5-dimethylphenyl)-4'-fluorophenyl methane with several aromatic dianhydrides. The one-step polymerization polyimides could be soluble not only in polar aprotic solvents, such as N-methyl-2-pyrrolidinone, and N,Ndimethylacetamide, but also in common organic solvents, such as chloroform, cyclopentanone, m-cresol and so on. The polyimide films show excellent transparency with the UV-Vis cut-off lengths of 310-360 nm and light transmittances of higher than 80% in the visible region. In addition, the polyimides exhibit good thermal stability with an initial decomposition temperature (Td) higher than 530℃ and have more than 60% of residual weight retentions at 700 ℃.

  2. A new high-performance ionic polymer-metal composite based on Nafion/polyimide blends

    Science.gov (United States)

    Nam, Jungsoo; Hwang, Taeseon; Kim, Kwang Jin; Lee, Dong-Chan

    2017-03-01

    For the first time, we report ion-exchange membranes based on Nafion and polyimide (PI, Kapton) blends to fabricate ionic polymer-metal composites (IPMCs). Polyamic acid [PAA, poly(pyromellitic dianhydride-co-4,4‧-oxydianiline), as a precursor of PI] solution was blended with Nafion solution using physical blending method to provide PAA-Nafion blend membrane. This work demonstrates that, by simple physical blending method, the thermal and mechanical properties of Nafion can be improved while maintaining the excellent actuating performance. After thermal imidization, PAA converted into PI, resulting in PI-Nafion blend membrane. Optimum conditions to cast PAA-Nafion blends and thermal imidization have been established, and blend membranes with PI wt% of 6, 12, 18, and 30 were prepared. Fourier transform infrared spectroscopy confirmed the incorporation of PI in the Nafion matrix. Thermal decomposition unique to the PI became more noticeable as the content of PI increased, which was measured by thermogravimetric analysis. Dynamic mechanical analysis showed that the storage modulus (E‧) increased as a function of PI content while loss modulus (E″) exhibited only a minor change, which resulted in the decrease in the damping properties (tan δ). The blend membranes were fabricated into IPMCs by deposition of platinum electrode onto the membrane surface through electroless plating process. Among tested, NPI-18 IPMC actuator, which has 18 wt% of PI in Nafion, showed comparable electromechanical performance to the commercially available Nafion 117 IPMC actuator.

  3. Synthesis and Properties Study of 2,5-bis(2-trifluoromethyl-4-aminophenoxy)toluene and Its Polyimide Film%2,5-双(2-三氟甲基-4-氨基苯氧基)甲苯及其聚酰亚胺薄膜的合成与性能研究

    Institute of Scientific and Technical Information of China (English)

    赵世图; 鲁云华; 赵洪斌; 胡知之

    2013-01-01

      用甲基氢醌和2-氯-5-硝基三氟甲苯通过亲核取代及还原反应合成出了一种二胺单体2,5-双(2-三氟甲基-4-氨基苯氧基)甲苯(DATHQ-2TF),采用该二胺单体和1,4-双(4-氨基-2-三氟甲基苯氧基)苯(6FAPB)分别与1,2,3,4-环丁烷四甲酸二酐(CBDA)反应制得聚酰胺酸(PAA),再经过热酰亚胺化制备出了聚酰亚胺薄膜PI-1和PI-2,并对其结构和性能进行研究。结果表明:两种薄膜均具有非常好的综合性能,薄膜在450 nm处的透光率都在80%以上,5%热分解温度均超过430℃,且都具有良好的溶解性能。由于甲基的引入使得PI-1薄膜比PI-2薄膜具有更好的溶解性,但光学透明性和热性能稍有下降。%  A diamine monomer 2,5-bis(2-trifluoromethy-4-aminophenoxy)toluene(DATHQ-2TF) was synthe-sized by nucleophilic substitution and reduction reaction between methylhydroquinone and 2-chloro-5-nitro benzotrifluoride. Two polyamide acid(PAA) solutions were prepared by the diamine monomer and 1,4-bis (2-trifluoromethyl-4-aminophenoxy)benzene(6FAPB) reacting with 1,2,3,4-cyclobutane dianhydride(CBDA) re-spectively, and then two polyimide (PI-1 and PI-2) films were prepared by thermal imidization, and their structure and properties were studied. The results show that the two PI films show excellent comprehen-sive performance with good solubility property, and the transmittance of the PI films at 450nm is over 80%, the 5% thermal decomposition temperature is over 430℃. Due to the introduction of -CH3 in PI-1, the PI-1 film has better solubility than PI-2 film, but its optical transparency and heat-resistance reduce slightly.

  4. SULFONATED POLYIMIDES CONTAINING PYRIDINE GROUPS AS PROTON EXCHANGE MEMBRANE MATERIALS

    Institute of Scientific and Technical Information of China (English)

    Rui Lei; Chuan-qing Kang; Yun-jie Huang; Xue-peng Qiu; Xiang-ling Ji; Wei Xing; Lian-xun Gao

    2011-01-01

    A series of sulfonated polyimides (SPIs) containing pyridine groups were prepared by direct polycondensation from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA),4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODADS) and 4-(4-methoxy)phenyl-2,6-bis(4-aminophenyl)pyridine (DAM).The resulting copolymers displayed good solubility in common organic solvents.Flexible,transparent,tough membranes were obtained via solution casting.All the films showed high thermal stability with desulfonation temperature over 300℃.They exhibited prominent mechanical properties with Young's modulus around 2.0 GPa.High proton conductivity (0.23 S/em at 100% RH) was also observed.More importantly,the new materials exhibited low water uptake (30 wt%-75 wt% at 80℃) and improved water stability,which were attributed to the acid-base interaction between sulfonic acid and pyridine functional groups.

  5. Synthesis and characterization of novel triptycene dianhydrides and polyimides of intrinsic microporosity based on 3,3ʹ-dimethylnaphthidine

    KAUST Repository

    Ghanem, Bader

    2016-08-29

    Two intrinsically microporous polyimides were obtained by high-temperature, one-pot poly-condensation reaction of novel triptycene-based dianhydrides containing dimethyl- or diisopropyl-bridgehead groups with a commercially available highly sterically hindered 3,3 \\'-dimethylnaphthidine (DMN) diamine monomer. The dimethyl bridgehead groups in the triptycene building block provided the DMN-based polyimide (TDA1-DMN) with larger surface area (760 m(2) g(-1)) than the diisopropyl-based polyimide (TDA1-DMN) (680 m(2) g(-1)), greater fraction of ultramicroporosity, as observed from N-2 and CO2 NLDFT adsorption analysis, and higher gas permeability and selectivity. Wide-angle X-ray diffraction (WAXD) measurements demonstrated that TDA1-DMN and TDAi3-DMN exhibited a bimodal pore size distribution, where TDA1-DMN showed smaller d-spacing values and broader intensity peaks. Both TDADMN-based polyimides showed very high gas permeabilities with moderate selectivities. For example, fresh TDA1-DMN exhibited an O-2 permeability of 783 Barrer coupled with an O-2/N-2 selectivity of 4.3 and H-2 permeability of 3050 Barrer with H-2/N-2 selectivity of 16.7, values that surpassed the 2008 Robeson permeability/selectivity upper bounds. Physical aging of the TDA-DMN polyimide films over a period of 250 days showed relatively small changes in permeability (similar to 20%) and selectivity (similar to 5%). (C) 2016 Elsevier Ltd. All rights reserved.

  6. Polyimides Derived from Novel Asymmetric Benzophenone Dianhydrides

    Science.gov (United States)

    Chuang, Chun-Hua (Inventor)

    2015-01-01

    This invention relates to the composition and processes for preparing thermoset polyimides derived from an asymmetric dianhydride, namely 2,3,3',4'-benzophenone dianhydride (a-BTDA) with at least one diamine, and a monofunctional terminal endcaps. The monofunctional terminating groups include 4-phenylethynylphthalic anhydride ester-acid derivatives, phenylethyl trimellitic anhydride (PETA) and its ester derivatives as well as 3-phenylethynylaniline. The process of polyimide composite comprises impregnating monomer reactants of dianhydride or its ester-acid derivatives, diamine and with monofunctional reactive endcaps into glass, carbon, quartz or synthetic fibers and fabrics, and then stack up into laminates and subsequently heated to between 150-375.degree. C. either at atmosphere or under pressure to promote the curing and crosslinking of the reactive endcaps to form a network of thermoset polyimides.

  7. Design and synthesis of flexible switching 1 × 2 antenna array on Kapton substrate

    Science.gov (United States)

    Georges Rabobason, Yvon; Rigas, Grigorios; Swaisaenyakorn, Srijittar; Mirkhaydarov, Bobur; Ravelo, Blaise; Shkunov, Maxim; Young, Paul; Benjelloun, Nabil

    2016-06-01

    Flexible front- and back-end RF/analogue system antennas were recently emerged. However, little flexible antenna system design is available so far, in planar hybrid technology with surface mounted components. This paper describes the design feasibility of flexible switching 1 × 2 antenna array system. It acts as a switching antenna implemented in hexapole configuration. The system is comprised of a key element RF switch terminated by two identical patch antennas associated to half-wave elementary transmission lines (TLs). A detailed theory illustrating the global S-parameter model determination in function of the given RF-switch return and insertion losses is established. In difference to the conventional microwave circuit theory, the proposed equivalent S-parameter model is originally built with the non-standard optimized antenna load. Thus, the synthesis method of the terminal antenna input impedance and the output access line characteristic impedance is formulated in function of the specified return and optimal transmission losses. The design method and theoretical approach feasibility is verified with the demonstrator of flexible switching 1 × 2 antenna array printed on Kapton substrate. The circuit prototype is implemented in hybrid planar technology integrating patch antenna operating at about 6 GHz and a packaged GaAs RF switch associated to the RF/DC signal decoupling accessory mounted surface components. Simulations of the designed circuit transmission and isolation losses from 5.5 GHz to 7 GHz were carried out by using the commercial RF switch S-parameter touchstone model provided by the manufacturer. The simulated and measured return losses are compared and discussed. Then, the measured radiation patterns confirm the proposed switched antenna concept feasibility.

  8. HPLC for quality control of polyimides

    Science.gov (United States)

    Young, P. R.; Sykes, G. F.

    1979-01-01

    High Pressure Liquid Chromatography (HPLC) as a quality control tool for polyimide resins and prepregs are presented. A data base to help establish accept/reject criteria for these materials was developed. This work is intended to supplement, not replace, standard quality control tests normally conducted on incoming resins and prepregs. To help achieve these objectives, the HPLC separation of LARC-160 polyimide precursor resin was characterized. Room temperature resin aging effects were studied. Graphite reinforced composites made from fresh and aged resin were fabricated and tested to determine if changes observed by HPLC were significant.

  9. HPLC for quality control of polyimides

    Science.gov (United States)

    Young, P. R.; Sykes, G. F.

    1979-01-01

    High Pressure Liquid Chromatography (HPLC) as a quality control tool for polyimide resins and prepregs are presented. A data base to help establish accept/reject criteria for these materials was developed. This work is intended to supplement, not replace, standard quality control tests normally conducted on incoming resins and prepregs. To help achieve these objectives, the HPLC separation of LARC-160 polyimide precursor resin was characterized. Room temperature resin aging effects were studied. Graphite reinforced composites made from fresh and aged resin were fabricated and tested to determine if changes observed by HPLC were significant.

  10. Performance of laser bonded glass/polyimide microjoints in cerebrospinal fluid.

    Science.gov (United States)

    Mian, A; Newaz, G; Georgiev, D G; Rahman, N; Vendra, L; Auner, G; Witte, R; Herfurth, H

    2007-03-01

    In this paper, laser bonded microjoints between glass and polyimide is considered to examine their potential applicability in encapsulating neural implants. To facilitate bonding between polyimide and glass, a thin titanium film with a thickness of 2 microm was deposited on borosilicate glass plates by a physical vapor deposition (PVD) process. Titanium coated glass was then joined with polyimide by using a cw fiber laser emitting at a wavelength of 1.1 microm (1.0 W) to prepare several tensile samples. Some of the samples were exposed to artificial cerebrospinal fluid (aCSF) at 37 degrees C for two weeks to assess long-term integrity of the joints. Both the as-received and aCSF soaked samples were subjected to uniaxial tensile loads for bond strengths measurements. The bond strengths for the as-received and aCSF soaked samples were measured to be 7.31 and 5.33 N/mm, respectively. Although the long-term exposure of the microjoints to aCSF has resulted in 26% reduction of bond strength, the samples still retain considerably high strength as compared with the titanium-polyimide samples. The failed glass/polyimide samples were also analyzed using optical microscopy, and failure mechanisms are discussed. In addition, a two dimensional finite element analysis (FEA) was conducted to understand the stress distribution within the substrate materials while the samples are in tension. The FEA results match reasonably well with the experimental load-displacement curves for as-received samples. Detailed discussion on various stress contours is presented in the paper, and the failure mechanisms observed from the experiment are shown in good agreement with the FEA predicted ones.

  11. Optical anisotropy of polyimide and polymethacrylate containing photocrosslinkable chalcone group in the side chain under irradiation of a linearly polarized UV light

    CERN Document Server

    Choi, D H

    2002-01-01

    Photocrosslinkable soluble polyimide and polymethacrylate compound were synthesized for studying the optically induced anisotropy of the thin films. Chalcone group was introduced into the side chain unit of two polymers. We observed a photodimerization behavior between the double bonds in the chalcone group and an optical anisotropy of these materials by irradiation of a linearly polarized UV light (LPL). Optical anisotropy of the thin film was also investigated by using polarized UV absorption spectroscopy.The dynamic property of optical anisotropy in photoreactive polyimide was compared to that in polymethacrylate containing chalcone group in the side chain.

  12. The piezoelectric effect on zinc oxide nano on polyimide substrate by spray pyrolysis

    Science.gov (United States)

    Idris, A. A. M.; Arsat, R.; Ahmad, M. K.

    2017-03-01

    This paper reports the effect of the deposition conditions crystal quality and film thickness of the Zinc Oxide (ZnO) film on the polyimide substrate. The ZnO film has been deposited by using the spray pyrolysis technique. This technique needs Zinc Nitrate Hexahydrate with the mixture of deionized water. At 350 °C, a higher c-axis preferred orientation at peak 0002 crystal orientation, which is critical for piezoelectric applications in ZnO thin films are obtained with the thickness of thin film is 300ηm. It also produces the 204.8 Hz of frequency which is higher than other frequency obtained by lower growth temperature.

  13. Origin and prevention of high contact resistance in multilevel metal-polyimide structures

    Science.gov (United States)

    Day, David R.; Senturia, Stephen D.

    1982-05-01

    When polyimide is used as the insulating dielectric in multilevel-metal structures, a high contact resistance can result within the interconnecting vias. This paper examines the particular case of oxygen plasma patterning of the polyimide using a photoresist mask. Auger analysis in combination with compositional depth profiling was employed on a series of samples to measure surface composition of etched vias in polyimide. Results show two effects which, together, can account for high contact resistance: first, there is a thicker than normal aluminum oxide layer on the first level metal surface (due to exposure to the oxygen plasma); second, there is a thin, etch-resistant carbonaceous film (due to redeposition of organic material during plasma etching) that prevents oxide thinning through chemical means. It was found that by lowering the plasma pressure to 50 mTorr near the end of the etch, the organic film can be removed. In the absence of the carbonaceous layer, the oxide can then be chemically thinned to produce clean aluminum surfaces within the vias.

  14. Branched Rod-Coil Polyimide-Poly(Alkylene Oxide) Copolymers and Electrolyte Compositions

    Science.gov (United States)

    Meador, Maryann B. (Inventor); Tigelaar, Dean M. (Inventor)

    2014-01-01

    Crosslinked polyimide-poly(alkylene oxide) copolymers capable of holding large volumes of liquid while maintaining good dimensional stability. Copolymers are derived at ambient temperatures from amine endcapped amic-acid oligomers subsequently imidized in solution at increased temperatures, followed by reaction with trifunctional compounds in the presence of various additives. Films of these copolymers hold over four times their weight at room temperature of liquids such as ionic liquids (RTIL) and/or carbonate solvents. These rod-coil polyimide copolymers are used to prepare polymeric electrolytes by adding to the copolymers various amounts of compounds such as ionic liquids (RTIL), lithium trifluoromethane-sulfonimide (LiTFSi) or other lithium salts, and alumina.

  15. Polyimide microfluidic devices with integrated nanoporous filtration areas manufactured by micromachining and ion track technology

    Science.gov (United States)

    Metz, S.; Trautmann, C.; Bertsch, A.; Renaud, Ph

    2004-03-01

    This paper reports on polyimide microfluidic devices fabricated by photolithography and a layer transfer lamination technology. The microchannels are sealed by laminating an uncured polyimide film on a partially cured layer and subsequent imidization. Selected areas of the microchannels were irradiated with heavy ions of several hundred MeV and the generated ion tracks are chemically etched to submicron pores of high aspect ratio. The ion beam parameters and the track etching conditions define density, length, diameter and shape of the pores. Membrane permeability and separation performance is demonstrated in cross-flow filtration experiments. The devices can be used for selective delivery or probing of fluids to biological tissue, e.g. drug delivery or microdialysis. For chip-based devices the filters can be used as a sample pre-treatment unit for filtration or concentration of particles or molecules.

  16. Durability of polyimide to titanium bonds

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Bhowmik, S.; Ernst, L.J.

    2012-01-01

    Titanium and its alloys are usually bonded together using a high temperature resistant polyimide or epoxy adhesives. Such adhesives can withstand temperatures from 200°C to300°C. Earlier research work indicates that Surface modification of titanium with mechanical treatment and atmospheric pressure

  17. 1-D nanochannels fabricated in polyimide

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Bomer, Johan; Tas, Niels R.; Berg, van den Albert

    2004-01-01

    A simple method using spin-deposition and sacrificial layer etching is used to fabricate all-polyimide nanochannels (100 and 500 nm channel height). Channels are characterized using spontaneous capillary filling with water, ethanol and isopropanol, and with electroosmotic flow. The channels can be p

  18. Stress evaluation in thin films: Micro-focus synchrotron X-ray diffraction combined with focused ion beam patterning for d{sub o} evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Baimpas, Nikolaos, E-mail: nikolaos.baimpas@eng.ox.ac.uk [University of Oxford, Dept. of Engineering Science (United Kingdom); Le Bourhis, Eric [University of Poitiers, Institut P' , Laboratoire de Physique des Matériaux, Poitiers (France); Eve, Sophie [ENSICAEN, CRISMAT, Caen (France); Thiaudière, Dominique [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, Paris (France); Hardie, Christopher [University of Oxford, Materials Department (United Kingdom); Korsunsky, Alexander M. [University of Oxford, Dept. of Engineering Science (United Kingdom)

    2013-12-31

    Nanocrystalline metallic coatings of sub-micron thickness are widely used in modern microelectronic applications. In X-ray diffraction experiments to determine both the residual and applied stresses in nanocrystalline coatings, one difficult challenge that comes up invariably is the determination of the strain-free lattice spacing d{sub o}. The present study addresses this challenge by using the focused ion beam (FIB) to generate a built-in strain-free reference by patterning (milling) a 50 × 50 μm{sup 2} region of the coating to produce an array of small stress-relieved “islands” ∼ 0.8 × 0.8 μm{sup 2} each. Transmission X-ray diffraction setup was used for data collection at DIFFABS beamline (Synchrotron SOLEIL, France). A 150 nm-thick multi-layered W–Cu nano-composite thin film on polyimide (Kapton®) substrate was studied. The samples were loaded incrementally using a compact uniaxial loading device, and micro-beam diffraction data were collected on and away from the reference array. It was shown experimentally that the “island” array remained approximately strain free throughout the experiment, providing an on-board d{sub o} lattice spacing reference. The changing lattice spacing d in the coating was also monitored away from the array, to deduce the elastic strain evolution during deformation. The results and their implications are presented and discussed. - Highlights: • In situ deformation study of laminate polycrystalline W–Cu thin films • Focused ion beam (FIB) patterning of an array of “islands” on thin films surface • X-ray diffraction on island-patterned region • Constant strain on “islands” independently of the deformation of the substrate.

  19. Metal-Ion Additives Reduce Thermal Expansion Of Polyimides

    Science.gov (United States)

    Stoakley, Diane M.; St. Clair, Anne K.; Emerson, Burt R., Jr.; Willis, George L.

    1994-01-01

    Polyimides widely used as high-performance polymers because of their excellent thermal stability and toughness. However, their coefficients of thermal expansion (CTE's) greater than those of metals, ceramics, and glasses. Decreasing CTE's of polyimides increase usefulness for aerospace and electronics applications in which dimensional stability required. Additives containing metal ions reduce coefficients of thermal expansion of polyimides. Reductions range from 11 to over 100 percent.

  20. Phosphorus-containing sulfonated polyimides for proton exchange membranes

    OpenAIRE

    2008-01-01

    Synthesis and characterization of the novel sulfonated BAPPO monomer and its use in the synthesis of a new phosphine oxide-based sulfonated polyimide are described. BTDA, 6FDA, and DDS were used as monomers in the polyimide synthesis. Sulfonated polyimide membranes were obtained by a solution thermal imidization method. The thermal behavior of the polymers was investigated by DSC and TGA. The morphological structure of the membranes was investigated by tapping-mode AFM. The proton conductivit...

  1. Fabrication and Properties of Nano-BaTiO_3/Polyimide Composite Film%纳米钛酸钡掺杂聚酰亚胺基高介电复合薄膜的制备及性能

    Institute of Scientific and Technical Information of China (English)

    翁凌; 刘立柱; 杨立倩; 曹振兴; 王诚

    2012-01-01

    Nano-BaTiO3/ polyimide(PI) composite films were prepared through high speed mechanical dispersion and in-situ polymerization.The microstructure,thermal stability and dielectric properties were investigated.The results indicate that the dispersion of BaTiO3 in PI matrix through high speed mechanical dispersion is better than that of in-situ polymerization.Moreover,it also indicates that both of the thermal stability and dielectric properties of BaTiO3/PI composite films increase with the BaTiO3's content increased.When the volume content of BaTiO3 reaches 50%,the dielectric constant of BaTiO3/PI composite films is 10 times higher than of pure PI film,but the dielectric loss is only 3 times higher than of pure PI.%采用原位聚合法和高速砂磨法制备了纳米钛酸钡/聚酰亚胺高介电常数复合薄膜,分析了不同制备方法及钛酸钡粉体用量对复合薄膜结构和性能的影响。实验结果表明,高速砂磨法对于纳米钛酸钡粉体的分散效果优于原位分散法;钛酸钡粉体的引入,有效提高了复合薄膜的热稳定性和介电性能。当粉体的体积分数达到50%时,复合薄膜介电常数相较于纯膜提高了10倍,而介电损耗只有少量增加。

  2. Performance of 6FDA–6FpDA polyimide for propylene/propane separations

    KAUST Repository

    Das, Mita

    2010-12-01

    This work addresses the challenges faced by previous researchers with 6FDA-6FpDA polyimide for propylene/propane separations due to plasticization. A study of film annealing temperature is reported to optimize plasticization suppression in elevated temperature permeation on properly annealed dense films made with high molecular weight polymer. A detailed analysis of pure and mixed gas results using different permeability models is shown in this work. The annealing effects in terms of plasticization suppression and permeability and selectivity changes are discussed in detail. According to our best knowledge, this is for the first time plasticization suppression for propylene/propane has been reported with any polyimide dense film membrane. Results of pure gas sorption experiments using a pressure decay method with un-annealed and annealed films are discussed and used to analyze the permeation data using the dual-mode model. Mixed gas permeation results also are explained with dual mode and bulk flow transport models. © 2010 Elsevier B.V.

  3. Polyimide surface modification by using microwave plasma for adhesion enhancement of Cu electroless plating.

    Science.gov (United States)

    Cho, Sang-Jin; Nguyen, Trieu; Boo, Jin-Hyo

    2011-06-01

    Microwave (MW) plasma was applied to the surface of polyimide (PI) films as a treatment to enhance the adhesion between copper deposition layer and PI surface for electroless plating. The influences of nitrogen MW plasma treatment on chemical composition of the PI surface were investigated by using X-Ray photoelectron spectroscopy (XPS). The wettability was also investigated by water contact angle measurement. The surface morphologies of PI films before and after treatment were characterized with atomic force microscopy (AFM). The contact angle results show that was dramatically decreased to 16.1 degrees at the optimal treatment condition from 72.1 degrees (untreated PI). However, the root mean square (RMS) roughness of treated PI film was almost unchanged. The AFM roughness was stayed from 1.0 to 1.2 with/without plasma treatment. XPS data show a nitrogen increase when PI films exposed to N2 MW plasma. Electroless copper depositions were carried out with the free-formaldehyde method using glyoxylic acid as the reducing reagent and mixture palladium chloride, tin chloride as activation solution. Adhesion property between polyimide surface and copper layer was investigated by tape test.

  4. Preparation and properties of nanoporous polyimide films with low dielectric permittivity%低介电常数聚酰亚胺薄膜的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    贾红娟; 尹训茜; 查俊伟; 施昌勇; 党智敏

    2011-01-01

    SiO2/polyimide(PI) nanocomposite films with low dielectric permittivity with diamines of pyromellitic dianhydride(PMDA) and 4,4-oxydianiline(ODA) were successfully synthesized by a wet phase inversion process.Then removal of the silica cores of the nano-composite films by HF etching gives rise to the nanoporous of PI films.It is found that the dielectric permittivities of the porous films can be reduced from 3.54 of the pure PI to 3.05(1kHz) by using 15 wt% pore-former(SiO2).The nanopores were characterized by transmission electron microscopy(TEM).The relationships between the structure of the films and the properties,including the dielectric permittivity,the heat resistance,the contact angles and the mechanical strength,were researched.%用单体4,4′-二胺基二苯醚(ODA)和均苯四甲酸二酐(PMDA)添加纳米SiO2,在溶剂N,N-二甲基乙酰胺(DMAC)中,采用原位聚合法合成SiO2/聚酰亚胺(PI)复合薄膜。用氢氟酸刻蚀SiO2纳米粒子,引入纳米微孔,形成含有微孔的PI薄膜。造孔剂含量为15%时,薄膜的介电常数从纯聚酰亚胺的3.54降低至3.05(1kHz)。用透射电镜表征微孔结构,分析了微孔孔径和造孔剂(SiO2)含量对薄膜介电常数、耐热性、疏水性和机械强度等性质的影响。

  5. Addition Polyimides from Non-Mutagenic Diamines

    Science.gov (United States)

    Delvigs, Peter; Klopotek, David L.; Hardy-Green, DeNise; Meador, Michael A. (Technical Monitor)

    2001-01-01

    Studies were conducted to find an acceptable non-mutagenic diamine to replace 4,4'-methylenedianiline (MDA), a suspect carcinogen, which is currently being used in PMR-15 polyimide applications. Several diamines containing fluorine and trifluoromethyl substituent groups were synthesized. The diamines were polymerized with the dimethyl ester of 3,3',4,4'-benzophenone tetracarboxylic acid (BTDE), using the monomethyl ester of nadic acid (NE) as an endcap. The effect of diamine structure on rheological properties, glass transition temperature, and thermo-oxidative stability was investigated. Unidirectional laminates were fabricated from selected resins, using carbon fiber as the reinforcement. The results indicate that some of the diamines containing trifluoromethyl groups are non-mutagenic, and have potential to replace MDA in PMR polyimides for long-term applications at temperatures up to 300 C.

  6. Investigation of the interfacial reaction between metal and fluorine-contained polyimides

    Science.gov (United States)

    Yang, Ching-Yu; Chen, J. S.; Hsu, S. L. C.

    2005-07-01

    In this work, thin metal films (Cr and Ta) were deposited on fluorine-contained polyimides, 6FDA-BisAAF, and 6FDA-PPD. The chemical states of the metal/polyimide samples were characterized by using x-ray photoelectron spectroscopy (XPS). XPS analysis reveals that metal-C, C-O, and metal-O bondings are present in metallized 6FDA-BisAAF and 6FDA-PPD. C-F bonds are observed in bare 6FDA-BisAAF and 6FDA-PPD however, they are not seen in the metallized samples. Disappearance of the C-F bonding is attributed to the disruption of CF3 side groups from the main chains of 6FDA-BisAAF and 6FDA-PPD when the chains are exposed to the plasma during the metal deposition. Nevertheless, the disruption of CF3 side groups also creates sites for the formation of metal-C or C-O bondings, which provide a positive adhesion strength at the metal/polyimide interface, as revealed by the tape test.

  7. Crack-resistant polyimide coating for high-capacity battery anodes

    Science.gov (United States)

    Li, Yingshun; Wang, Shuo; Lee, Pui-Kit; He, Jieqing; Yu, Denis Y. W.

    2017-10-01

    Electrode cracking is a serious problem that hinders the application of many next-generation high-capacity anode materials for lithium-ion batteries. Even though nano-sizing the material can reduce fracturing of individual particles, capacity fading is still observed due to large volume change and loss of contact in the electrode during lithium insertion and extraction. In this study, we design a crack-resistant high-modulus polyimide coating with high compressive strength which can hold multiple particles together during charge and discharge to maintain contact. The effectiveness of the coating is demonstrated on tin dioxide, a high-capacity large-volume-change material that undergoes both alloy and conversion reactions. The polyimide coating improves capacity retention of SnO2 from 80% to 100% after 80 cycles at 250 mA g-1. Stable capacity of 585 mAh g-1 can be obtained even at 500 mA g-1 after 300 cycles. Scanning electron microscopy and in-situ dilatometry confirm that electrode cracking is suppressed and thickness change is reduced with the coating. In addition, the chemically-stable polyimide film can separate the surface from direct contact with electrolyte, improving coulombic efficiency to ∼100%. We expect the novel strategy of suppressing electrode degradation with a crack-resistant coating can also be used for other alloy and conversion-based anodes.

  8. Thermal degradation of organo-soluble polyimides

    Institute of Scientific and Technical Information of China (English)

    黄俐研; 史燚; 金熹高

    1999-01-01

    The thermal degradation behavior of two organo-soluble polyimides was investigated by high resolution pyrolysis-gas chromatography/mass spectrometry. The pyrolyzates of the polymers at various temperatures were identified and characterized quantitatively. The relationship between the polymer structure and pyrolyzate distribution was discussed. The kinetic parameters of the thermal degradation were calculated based on thermogravimetric measurements. Finally, the thermal degradation mechanism for the polymers was suggested.

  9. Study on Synthesis and Dielectric Properties of Polyimide Nano-alumina Composite Films%耐高温聚酰亚胺/纳米复合薄膜的合成及其电性能研究

    Institute of Scientific and Technical Information of China (English)

    严伟兴; 邹敏; 张飞; 李晓奋; 胡大宁

    2014-01-01

    制备均苯型聚酰亚胺/纳米三氧化二铝复合薄膜,通过超声机械共混法对纳米颗粒进行物理分散,使用扫描电镜(SEM)、红外光谱(FT-IR)分别对复合材料表面微观形貌和结构进行了表征与研究,通过介电谱测试系统对PI复合材料进行电性能方面的分析研究。结果发现:纳米颗粒分散均匀,超声波对纳米颗粒有很好的分散效果;频率在102~105Hz之间, PI复合薄膜介电常数和介电损耗角正切随纳米Al2O3含量质量分数的增加而增大。%Polypyromellitimide/nano-alumina composite films were prepared. Nano-particles were dispersed by ultrasonic-mechanical mixing method. The surface morphology and structure of PI composite film were examined and characterized by SEM and FTIR spectrometer, and the electrical properties were researched by use of dielectric spectroscopy test system. The results showed that dielectric constant and the dielectric loss of composite film improve when the content of nano-alumina was increasing between 102~105Hz.

  10. Melamine Polyimide Composite Fire Resistant Intumescent Coatings

    Directory of Open Access Journals (Sweden)

    Satish Chandra Gupta

    2013-07-01

    Full Text Available Components of intumescent coatings acid source, carbon source and blowing agent like melamine linked together by a binder provide cumulative fire retardant properties. When temperature of the coating surface reaches a critical temperature under the heat of flame, the surface begins to melt and is converted into highly viscous liquid. Simultaneously, reactions are initiated that result in the release of inert gases with low thermal conductivity. These gases are trapped inside the viscous fluid forming insulating char. The special composite of melamine polyimide, a C source and melamine a blowing agent showed high performance heat resistance in the present study. Polyimides have excellent heat and chemical resistance, excellent adhesion to a number of substrates and superior mechanical properties, such as high flexural modulus and compressive strength. Polyimides are also known to possess outstanding dimensional stability under loads, which allows their use in high temperature environments. Effect of the monomer on chemical reactivity between the binder and the intumescent additives has been studied by thermo-gravimetric analysis, differential scanning calorimeter and FTIR analysis. Thermal insulation studies by various intumescent composite coatings, applied on aluminium plates provided useful time temperature profiles.Defence Science Journal, 2013, 63(4, pp.442-446, DOI:http://dx.doi.org/10.14429/dsj.63.4871

  11. Melamine Polyimide Composite Fire Resistant Intumescent Coatings

    Directory of Open Access Journals (Sweden)

    Satish Chandra Gupta

    2013-07-01

    Full Text Available Components of intumescent coatings acid source, carbon source and blowing agent like melamine linked together by a binder provide cumulative fire retardant properties. When temperature of the coating surface reaches a critical temperature under the heat of flame, the surface begins to melt and is converted into highly viscous liquid. Simultaneously, reactions are initiated that result in the release of inert gases with low thermal conductivity. These gases are trapped inside the viscous fluid forming insulating char. The special composite of melamine polyimide, a C source and melamine a blowing agent showed high performance heat resistance in the present study. Polyimides have excellent heat and chemical resistance, excellent adhesion to a number of substrates and superior mechanical properties, such as high flexural modulus and compressive strength. Polyimides are also known to possess outstanding dimensional stability under loads, which allows their use in high temperature environments. Effect of the monomer on chemical reactivity between the binder and the intumescent additives has been studied by thermo-gravimetric analysis, differential scanning calorimeter and FTIR analysis. Thermal insulation studies by various intumescent composite coatings, applied on aluminium plates provided useful time temperature profiles.

  12. Effects of imidization and rubbing of polyimides on their surface free energy

    Science.gov (United States)

    Borycki, Jerzy; Okulska-Bozek, Malgorzata

    2002-06-01

    According to classical method polyimides were obtained in two-step polycondensation process via 10% solutions of poly(amic acid)s in dimethylformamide (DMF). Poly(amic acid)s were synthesized from chosen tetracarboxylic acids dianhydrides: pyromellitic (PMDA), 4,4'- (hexafluoroisopropylidene)diphthalic (6FDA), 4,4'- oxydiphthalic (ODPA) and aromatic diamines: 4,4'- oxydianiline (ODA), 1,4-phenylenediamine (PPD), 4,4'- ethylenedianiline (DAB), 4,4'-diaminodiphenylmethane (MDA), 4-methyl-1,3-phenylenediamine (MMPD) and 2,3,5,6- tetramethyl-1,4-phenylenediamine (DAD) in the first step of this reaction. The indium tin oxide (ITO)-glass plates or glass plates were spin-coated with the poly(amic acid)s solutions and dried. The polyimide layers were prepared by gradual heating in various temperatures (100 degree(s)C, 150 degree(s)C, 180 degree(s)C, 200 degree(s)C, 220 degree(s)C and 250 degree(s)C). The degree of imidization was estimated by means of IR spectroscopy. Obtained PI layers were mechanically modified by rubbing. Three various rubbing materials were used: cotton, silk and chamois leather. Surface free energy and its components of polymer layers were evaluated on the basis of their wet ability by standard liquids (diiodomethane, 1- bromonaphthalene, formamide, ethylene glycol, water). It was found that decrease of intensity of rubbing process yields to increase of contact angle for each of rubbing materials. Polyimide layers rubbed with chamois leather were characterized by the best wet ability. The rubbing process increase surface free energy of tested polyimide films.

  13. Contact angle hysteresis: study by dynamic cycling contact angle measurements and variable angle spectroscopic ellipsometry on polyimide.

    Science.gov (United States)

    Hennig, A; Eichhorn, K-J; Staudinger, U; Sahre, K; Rogalli, M; Stamm, M; Neumann, A W; Grundke, K

    2004-08-03

    The phenomenon of contact angle hysteresis was studied on smooth films of polyimide, a polymer type used in the microelectronic industry, by dynamic cycling contact angle measurements based on axisymmetric drop shape analysis-profile in combination with variable angle spectroscopic ellipsometry (VASE). It was found that both advancing and receding contact angles became smaller with increasing the number of cycles and are, therefore, not a property of the dry solid alone. The changes of the wetting behavior during these dynamic cycling contact angle measurements are attributed mainly to swelling and/or liquid retention. To reveal the water-induced changes of the polymer film, the polyimide surface was studied before and after the contact with a water droplet by VASE. Both the experimental ellipsometric spectrum for Delta and that for Psi as well as the corresponding simulations show characteristic shifts due to the contact with water. The so-called effective medium approximation was applied to recover information about the thickness and effective optical constants of the polymer layer from the ellipsometrically measured values of Delta and Psi. On the basis of these results, the swelling and retention behavior of the polyimide films in contact with water droplets were discussed.

  14. Frequency-dependent dielectric response model for polyimide-poly(vinilydenefluoride) multilayered dielectrics

    Science.gov (United States)

    Di Lillo, Luigi; Bergamini, Andrea; Albino Carnelli, Dario; Ermanni, Paolo

    2012-07-01

    A physical model for the frequency-dependent dielectric response of multilayered structures is reported. Two frequency regimes defined by the relative permittivities and volume resistivities of the layers have been analytically identified and experimentally investigated on a structure consisting of polyimide and poly(vinilydenefluoride) layers. The relative permittivity follows an effective medium model at high frequency while showing a dependence on the volume resistivity at low frequency. In this regime, relative permittivities exceeding those expected from effective medium model are recorded. These findings provide insights into inhomogeneous dielectrics behavior for the development of high energy density dielectric films.

  15. Polyimide Aerogels with Three-Dimensional Cross-Linked Structure

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor)

    2016-01-01

    A method for creating a three dimensional cross-linked polyimide structure includes dissolving a diamine, a dianhydride, and a triamine in a solvent, imidizing a polyamic acid gel by heating the gel, extracting the gel in a second solvent, supercritically drying the gel, and removing the solvent to create a polyimide aerogel.

  16. Dielectric property of polyimide/barium titanate composites and its influence factors (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Weidong LIU; Baoku ZHU; Shuhui XIE; Zhikang XU

    2008-01-01

    Using poly(amic acid) (PAA) as a precursor followed by thermal imidization, the polyimide/barium titanate composite films were successfully prepared by a direct mixing method and in situ process. The influence of processing factors, such as particle size, distribution mode and polymerization method on dielectric prop-erties was studied. Results revealed that the dielectric constant (ε) of the composite film increased by using bigger fillers or employing in situ polymerization and bimodal distribution. When the composite film contain-ing 50 Vol-% of BaTiO3 with size in 100 nm was pre-pared via in situ process, its dielectric constant reached 45 at 10 kHz.

  17. Synthesis, characterizations and electro-optical properties of nonlinear optical polyimide/silica hybrid

    Directory of Open Access Journals (Sweden)

    2007-03-01

    Full Text Available Transparent Nonlinear Optical (NLO inorganic/organic (polyimide/silica hybrid composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. The silica content in the hybrid films was varied from 0 to 22.5/wt%. The prepared PI hybrids were characterized by IR, UV-Vis, Thermogravimetric analysis (TGA, X-ray diffraction (XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM. They exhibited fair good optical transparency. The SiO2 phase was well dispersed in the polymer matrix. DSC and TGA results showed that these hybrid materials had excellent thermal stability. The polymer solutions could be spin coated on the indium-tin-oxide (ITO glass to form optical quality thin films. The electro-optic coefficients (γ33 at the wavelength of 832 nm for polymer thin films poled were in the range of 19-27 pm/V.

  18. Synthesis of nonlinear optical fluorinated polyimide/inorganic composites for photonic devices

    Institute of Scientific and Technical Information of China (English)

    LI Guo-yuan; REN Li

    2006-01-01

    A nonlinear optical (NLO) active alkoxysilane chromophore (SGDR1) was synthesized. A fluorinated polyimide/SGDR1 composite was prepared to improve the poor temporal stability of second-order NLO effects of the reported poled sol-gel film. The poled composite film was characterized by FTIR,DSC,TGA and UV-Vis. The composite displays good hydrophobic properties,high glass transition temperature (266 ℃),and high decomposition temperature (433 ℃). The second harmonic coefficient d33 of the composite was measured to be 16.77 pm/V by using maker fringe technique. The new NLO composite exhibits 85 % of the original d33 over 720 h at 100 ℃ and possesses much better stability than the reported sol-gel film.

  19. Hybrid copper complex-derived conductive patterns printed on polyimide substrates

    Science.gov (United States)

    Lee, Byoungyoon; Jeong, Sooncheol; Kim, Yoonhyun; Jeong, Inbum; Woo, Kyoohee; Moon, Jooho

    2012-06-01

    We synthesized new copper complexes that can be readily converted into highly conductive Cu film. Mechanochemical milling of copper (I) oxide suspended in formic acid resulted in the submicron-sized Cu formate together Cu nanoparticles. The submicrometer-sized Cu formates are reactive toward inter-particle sintering and metallic Cu seeds present in the Cu complexes assist their decomposition and the nucleation of Cu. The hybrid copper complex film printed on polyimide substrate is decomposed into dense and uniform Cu layer after annealing at 250 °C for 30 min under nitrogen atmosphere. The resulting Cu film exhibited a low resistivity of 8.2 μΩ·cm and good adhesion characteristics.

  20. Polyhedral Oligomeric Silsesquioxane (POSS) Polyimides as Space-Survivable Materials (Preprint)

    Science.gov (United States)

    2006-07-27

    Survivable Materials (Preprint) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Sandra J. Tomczak (AFRL/PRSM...Multiple samples of Kapton H®, 8.75 % Si8O11 MC-POSS PI, and silica-coated Kapton HN® (provided by Astral Technology Unlimited, Inc. Lot No. 00625-007...self-passivation experiment. (a.) Kapton H®, (b.) SiO2 coated Kapton HN® (Provided by Astral Industries Inc.), and (c.) 8.75 wt % Si8O11 cage MC

  1. SYNTHESIS AND CHARACTERIZATION OF ORGANO-SOLUBLE FLUORINATED POLYIMIDES FROM 4,4'-BIS(3-AMINO-5-TRIFLUOROMETHYLPHENOXY)-BIPHENYL AND VARIOUS AROMATIC DIANHYDRIDES

    Institute of Scientific and Technical Information of China (English)

    Gui-long Wu; Jin-gang Liu; Zuo-bang Li; Zi-yi Ge; Lin Fan; Shi-yong Yang

    2005-01-01

    An aromatic diamine monomer, 4,4'-bis(3-amino-5-trifluoromethyl phenoxy)-biphenyl (TFBPDA), was synthesized via the nucleophilic displacement reaction of 3,5-dinitrobenzotrifluoride and 4,4'-biphenol. The monomer was reacted with various aromatic dianhydrides via the high temperature polycondensation procedure to provide a series of polyimides. The polyimides, PI-1 to PI-4, show good solubility not only in aprotic solvents, such as N-methyl-2-pyrrolidinone and N,N-dimethylacetamide, but also in many common solvents, such as m-cresol, chloroform and cyclopentanone. PI-4, derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and TFBPDA, was even soluble in toluene. Moreover, PI films exhibit good thermal stability, outstanding transparency in the visible light region and acceptable mechanical and electrical properties. The excellent combined properties of the polyimides make them as a good candidate for fabricating microelectronics.

  2. Thermal, optical and photoinduced properties of a series of homo and co-polyimides with two kinds of covalently bonded azo-dyes and their supramolecular counterparts

    Science.gov (United States)

    Konieczkowska, Jolanta; Wojtowicz, Magdalena; Sobolewska, Anna; Noga, Joanna; Jarczyk-Jedryka, Anna; Kozanecka-Szmigiel, Anna; Schab-Balcerzak, Ewa

    2015-10-01

    The paper describes the synthesis and characterization of new aromatic polyimides with one or two different moieties of the azo-dyes covalently attached to the polymer backbone and their supramolecular analogues. Azo-functionalized polyimides were prepared using post-polymerization method including the introduction of Disperse Red 13 and/or 4-[4-(6-hydroxyhexyloxy)phenylazo]pyridine to homo and co-polyimides containing hydroxyl groups via Mitsunobu reaction. The degree of functionalization of polymers with chromophores was estimated by UV-Vis spectroscopy. Polyimides containing hydroxyl groups were applied as matrixes to create supramolecular systems based on hydrogen bonds. Hydrogen-bond interactions in azosystems were studied by FTIR spectroscopy. The polymers were characterized by 1H NMR, FTIR, X-ray, UV-Vis, DSC and TGA methods. The photoisomerization process was investigated in supramolecular systems. The light-induced anisotropy was studied in a holographic gratings recording experiment and by photoinduced birefringence measurements. The polymer films were investigated by atomic force microscopy (AFM) after the diffraction grating recording to confirm formation of surface relief gratings (SRGs). To the best of our knowledge, that the first time photoinduced anisotropy has been studied by birefringence measurements in polyimides containing two different azo-dyes.

  3. Directly patternable dielectric based on fluorinated polyimide

    Science.gov (United States)

    Dick, Andrew R.; Bell, William K.; Luke, Brendan; Maines, Erin; Mueller, Brennan; Kohl, Paul A.; Rawlings, Brandon; Willson, C. Grant

    2015-03-01

    A photosensitive polyimide system based on amine catalyzed imidization of a precursor poly(amic ester) is described. The material is based on the meta ethyl ester of pyromellitic dianhydride and 2,2' bis(trifluoromethyl)benzidine and acts as a negative tone resist when formulated with a photobase generator. The material exhibits a dielectric constant of 3.0 in the GHz range, a coefficient of thermal expansion of 6+/-2 ppm/K, and can be patterned to aspect ratios of greater than 2 when formulated with a high efficiency cinnamide type photobase generator.

  4. Liquid crystalline thermosetting polyimides. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, A.E.; Huang, S.J. [Connecticut Univ., Storrs, CT (United States). Inst. of Materials Science

    1993-07-01

    Phase separation of rodlike reinforcing polymers and flexible coil matrix polymers is a common problem in formulating molecular composites. One way to reduce phase separation might be to employ liquid crystalline thermosets as the matrix material. In this work, functionally terminated polyimide oligomers which exhibit lyotropic liquid crystalline behavior were successfully prepared. Materials based on 2,2{prime}-bis(trifluoromethyl)-4,4{prime}-diaminobiphenyl and 3,3{prime},4,4{prime}-biphenylenetetra-carboxylic dianhydride have been synthesized and characterized.

  5. Calculation Method for the Thermal Aging of Polyimide / Al2O3 Hybrid Films%聚酰亚胺/Al2O3掺杂薄膜热老化寿命计算方法研究

    Institute of Scientific and Technical Information of China (English)

    周浩然; 柳长富; 赵蕊; 崔晓禹; 孙安

    2012-01-01

    The thermal stabilization of PI / Al2 Q3 hybrid films was studied with TG. Meanwhile, the kinetics parameters (activation energy of thermal decomposition, collision coefficient and action progression) were calculated, and the upper limit temperature was predicted according to the relevant data. The experiment results showed that the order of reaction in air atmosphere was bigger than that in nitrogen atmosphere, and tended to second-order reaction. The value of E calculated by the method of Kissinger was lower than that in the method of Coats-Red fern. The collide coefficient (A) was calculated in the method of Coats-Red fern selected by contrast, and the upper limit temperatures of hybrid PI material was nearly 300 ℃ similar to those reported in previous literatures. The results have shown that Coats-Red fern method is one of the reliable methods to predict the long-term life upper limit temperature of hybrid PI materials.%利用热失重仪(TG)测定了Al2O3掺杂聚酰亚胺的热稳定性,采用Kissinger法和Coats-Red fern法计算动力学参数,预测杂化薄膜长期使用的上限温度.实验结果表明:在空气气氛中的反应级数大于氮气气氛中的反应级数,且趋于二级反应.利用Kissinger法求出的E值低于Coats-Redfern法求出的E值,选取Coats-Redfern法求取相应的碰撞系数(A)值后,预测杂化PI膜长期使用的上限温度在300℃左右,与文献报道基本相符.结果表明Coats-Red fern方法是预测杂化PI材料长期使用上限温度的可靠方法之一.

  6. Nanocrystallization of LiCoO2 Cathodes for Thin Film Batteries Utilizing Pulse Thermal Processing

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-01

    This factsheet describes a study whose focus is on the nanocrystallization of the LiCoO2 cathode thin films on polyimide substrates and evaluate the microstructural evolution and resistance as a function of PTP processing conditions.

  7. Surface modified Al2O3 in fluorinated polyimide/Al2O3 nanocomposites: Synthesis and characterization

    Indian Academy of Sciences (India)

    Zivar Ghezelbash; Davoud Ashouri; Saman Mousavian; Amir Hossein Ghandi; Yaghoub Rahnama

    2012-11-01

    Organic–inorganic hybrid materials consisting of inorganic materials and organic polymers are a new class of materials, which have received much attention in recent years. In the present investigation, at first, the surface of nano-alumina (Al2O3) was treated with a silane coupling agent of -aminopropyltriethoxysilane (KH550), which introduces organic functional groups on the surface of Al2O3 nanoparticles. Then fluorinated polyimide (PI) was synthesized from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride and 4,4'-diaminodiphenylsulfone. Finally, PI/modified Al2O3 nanocomposite films having 3, 5, 7 and 10% of Al2O3 were successfully prepared by an in situ polymerization reaction through thermal imidization. The obtained nanocomposites were characterized by fourier transform infrared spectroscopy, thermogravimetry analysis, X-ray powder diffraction, UV-Vis spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. The results show that the Al2O3 nanoparticles were dispersed homogeneously in PI matrix. According to thermogravimetry analysis results, the addition of these nanoparticles improved thermal stability of the obtained hybrid materials.

  8. Understanding the strength of epoxy/polyimide interfaces

    Science.gov (United States)

    Hoontrakul, Patraporn

    Polyimides are commonly used as organic passivation layers for microelectronic devices due to their unique combination of low dielectric constant, high thermal stability, and excellent mechanical properties. Polyimides are well known to have poor adhesion to epoxy resins. Many surface treatment methods have been developed to increase epoxy-polyimide adhesion. These include various ion beam and plasma treatments as well as wet chemical methods. Our research goal is to understand the strength of epoxy-polyimide interfaces by studying the effect of polyimide chemical structure on epoxy-polyimide adhesion. Four polyimides that were chosen in this study were commonly used in microelectronic industries: poly (pyromellitic dianhydride-oxydianiline [PMDA-ODA], poly (3,3',4,4'-biphenyltetracarboxylic dianhydride-phenylene diamine [BPDA-PDA], poly (hexafluoroisopropylidene-diphthalic anhydride-oxydianiline) [6FDA-ODA], and 5(6)-Amino-1-(4-aminophenyl)-1,3,3, trimethylindanbenzophenonetetacarboxylic dianhydride copolymer [BTDA-DAPI). The adhesive strengths between an epoxy resin and these various polyimides were characterized using interfacial fracture mechanics and the critical interfacial strain energy release rates were found to be in the range of 20 J/m 2 to 179 J/m2. The locus of failure for fractured epoxy-polyimide interfaces were analyzed using scanning electron microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FT-IR) and found to be at the interphase region for all four interfaces. The surface reactivity was analyzed using flow microcalorimetry (FMC), FT-IR, and the contact angles. Interestingly, the strength of the interfaces appeared to be related to the predicted interfacial widths from solubility parameter theory.

  9. SYNTHESIS AND CHARACTERIZATION OF ORGANSOLUBLE POLYIMIDE AND COPOLYIMIDES FROM ALICYCLIC DIANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A kind of highly organsoluble polyimide and copolyimides were successfully synthesized from bicyclo(2.2.2)-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA), the commercial diamine 4,4'-methylenedianiline (MDA) and the designed diamine 4,4'-methylenebis-(2-tert-butylaniline) (MBTBA). The polyimide from BCDA and MBTBA is highly soluble in convenfonal low boiling point solvents (such as chloroform, tetrahydrofuran) at room temperature. But the solubility of the copolyimides in conventional solvents decreased with the molar ratio of MBTBA and MDA decreased. When the molar ratio of MBTBA and MDA was larger than 7/3, the copolyimides can be soluble in low boiling point solvents at room temperature to form a transparent, flexible, tough film by solution casting. When the molar ratio of MBTBA and MDA was between 7/3 and 1/9, they can only be soluble in hot dipolar aprotic solvents (such as DMF, NMP etc.) and form films too. The copolyimide was only soluble in m-cresol when the molar ratio of MBTBA and MDA was lower than 1/9. The number-average molecular weights of the soluble copolyimides were larger than 5.8 × 104 g/mol by GPC and their polydispersity indices were higher than 1.4. Only one glass transition temperature of these copolyimides was detected around 400℃ by DMA. The copolyimides did not show appreciable decomposition up to 430℃ in N2.

  10. Improved PMR Polyimides For Heat-Stable Laminates

    Science.gov (United States)

    Vannucci, R. D.; Malarik, D. C.; Papadapoulos, D. S.; Waters, John F.

    1994-01-01

    Second-generation PMR-type polyimides (PMR-II polyimides) of enhanced thermo-oxidative stability prepared by substitution of para-aminostyrene (PAS) end caps for nadic-ester (NE) end caps used in prior PMR-II polyimides. Laminates unidirectionally reinforced with graphite fibers and made with PAS-capped resins exhibited thermo-oxidative stabilities significantly greater than those of similar laminates made with NE-capped PMR-II resins. One new laminate exhibited high retention of weight and strength after 1,000 h of exposure to air at 371 degrees C.

  11. Molecular Dynamics Simulation of Glass Transition Behavior of Polyimide Ensemble

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of chromophores to the glass transition temperature of polyimide ensemble has been investigated by means of molecular dynamics simulation in conjunction with barrier analysis. Simulated Tg results indicated a good agreement with experimental value. This study showed the MD simulation could estimate the effect of chromophores to the Tg of polyimide ensemble conveniently and an estimation approach method had a surprising deviation of Tg from experiment. At the same time, a polyimide structure with higher barrier energy was designed and validated by MD simulation.

  12. Flexible Microstrip Circuits for Superconducting Electronics

    Science.gov (United States)

    Chervenak, James; Mateo, Jennette

    2013-01-01

    Flexible circuits with superconducting wiring atop polyimide thin films are being studied to connect large numbers of wires between stages in cryogenic apparatus with low heat load. The feasibility of a full microstrip process, consisting of two layers of superconducting material separated by a thin dielectric layer on 5 mil (approximately 0.13 mm) Kapton sheets, where manageable residual stress remains in the polyimide film after processing, has been demonstrated. The goal is a 2-mil (approximately 0.051-mm) process using spin-on polyimide to take advantage of the smoother polyimide surface for achieving highquality metal films. Integration of microstrip wiring with this polyimide film may require high-temperature bakes to relax the stress in the polyimide film between metallization steps.

  13. Thermal runaway in polyimide at high electric field probed by infrared thermography

    Science.gov (United States)

    Diaham, Sombel; Belijar, Guillaume; Locatelli, Marie-Laure; Lebey, Thierry

    2015-03-01

    An original way for characterizing dielectrics under high electric field and high temperature based on the coupling between electric current measurements and real-time fast infrared (IR) thermography is demonstrated. Particularly, the Joule heating phenomenon at high field is quantified by 2D-temperature cartography in a polyimide (PI) film set at an initial temperature of 300 °C through IR observations of the polarized electrode. 2D-temperature cartography highlights the temperature increase with increasing the electric field. The thermal runway occurs prior to the dielectric breakdown from an electric field threshold of 140-150 V/μm. This corresponds to a dissipated volume power density between 2 and 5 mW/μm3. Such values report the limit of the electro-thermal equilibrium in PI film.

  14. Carbon molecular sieve membranes derived from Matrimid® polyimide for nitrogen/methane separation

    KAUST Repository

    Ning, Xue

    2014-01-01

    A commercial polyimide, Matrimid® 5218, was pyrolyzed under an inert argon atmosphere to produce carbon molecular sieve (CMS) dense film membranes for nitrogen/methane separation. The resulting CMS dense film separation performance was evaluated using both pure and mixed N2/CH4 permeation tests. The effects of final pyrolysis temperature on N 2/CH4 separation are reported. The separation performance of all CMS dense films significantly exceeds the polymer precursor dense film. The CMS dense film pyrolyzed at 800 C shows very attractive separation performance that surpasses the polymer membrane upper bound line, with N 2 permeability of 6.8 Barrers and N2/CH4 permselectivity of 7.7 from pure gas permeation, and N2 permeability of 5.2 Barrers and N2/CH4 permselectivity of 6.0 from mixed gas permeation. The temperature dependences of permeabilities, sorption coefficients, and diffusion coefficients of the membrane were studied, and the activation energy for permeation and diffusion, as well as the apparent heats of sorption are reported. The high permselectivity of this dense film is shown to arise from a significant entropic contribution in the diffusion selectivity. The study shows that the rigid \\'slit-shaped\\' CMS pore structure can enable a strong molecular sieving effect to effectively distinguish the size and shape difference between N2 and CH4. © 2013 Elsevier Ltd. All rights reserved.

  15. International Conference on Langmuir-Blodgett Films (5th) Held in Paris, France on 26-30 August 1991, Abstracts Booklet

    Science.gov (United States)

    1991-08-01

    microstructures. AP5 ORIENTATION OF POLYIMIDE LB FILMS IN PLANE DIRECTION Masa-aki Kakimoto, Yasunari Nishikata, Ken Komatsu, and Yoshio Imai Department...AND PROPERTIES OF POLYAMINE LB FILMS Toshihiro Suwa, Yasunari Nishikata, Hasa-aki Kakimoto, and Yoshio Imai Department of Organic and Polymeric...working Resists Using a Polyimide Langmuir-Blodgett Film System Mitsumasa Iwamoto*, Sige asba , Keiji Iriyama-, Yasunari Nishikata++ , Masaaki Kakimoto

  16. Low coefficient of thermal expansion polyimides containing metal ion additives

    Science.gov (United States)

    Stoakley, D. M.; St. Clair, A. K.

    1992-01-01

    Polyimides have become widely used as high performance polymers as a result of their excellent thermal stability and toughness. However, lowering their coefficient of thermal expansion (CTE) would increase their usefulness for aerospace and electronic applications where dimensional stability is a requirement. The incorporation of metal ion-containing additives into polyimides, resulting in significantly lowered CTE's, has been studied. Various metal ion additives have been added to both polyamic acid resins and soluble polyimide solutions in the concentration range of 4-23 weight percent. The incorporation of these metal ions has resulted in reductions in the CTE's of the control polyimides of 12 percent to over 100 percent depending on the choice of additive and its concentration.

  17. Low dielectric polyimide aerogels as substrates for lightweight patch antennas.

    Science.gov (United States)

    Meador, Mary Ann B; Wright, Sarah; Sandberg, Anna; Nguyen, Baochau N; Van Keuls, Frederick W; Mueller, Carl H; Rodríguez-Solís, Rafael; Miranda, Félix A

    2012-11-01

    The dielectric properties and loss tangents of low-density polyimide aerogels have been characterized at various frequencies. Relative dielectric constants as low as 1.16 were measured for polyimide aerogels made from 2,2'-dimethylbenzidine (DMBZ) and biphenyl 3,3',4,4'-tetracarbozylic dianhydride (BPDA) cross-linked with 1,3,5-triaminophenoxybenzene (TAB). This formulation was used as the substrate to fabricate and test prototype microstrip patch antennas and benchmark against state of practice commercial antenna substrates. The polyimide aerogel antennas exhibited broader bandwidth, higher gain, and lower mass than the antennas made using commercial substrates. These are very encouraging results, which support the potential advantages of the polyimide aerogel-based antennas for aerospace applications.

  18. Cyclopentadiene evolution during pyrolysis-gas chromatography of PMR polyimides

    Science.gov (United States)

    Alston, William B.; Gluyas, Richard E.; Snyder, William J.

    1992-01-01

    The effect of formulated molecular weight (FMW), extent of cure, and cumulative aging on the amount of cyclopentadiene (CPD) evolved from Polymerization of Monomeric Reactants (PMR) polyimides were investigated by pyrolysis-gas chromotography (PY-GC). The PMR polyimides are additional crosslinked resins formed from an aromatic diamine, a diester of an aromatic tetracarboxylic acid and a monoester of 5-norbornene-2, 3-dicarboxylic acid. The PY-GC results were related to the degree of crosslinking and to the thermo-oxidative stability (weight loss) of PMR polyimides. Thus, PY-GC has shown to be a valid technique for the characterization of PMR polyimide resins and composites via correlation of the CPD evolved versus the thermal history of the PMR sample.

  19. Statistical Design in Isothermal Aging of Polyimide Resins

    Science.gov (United States)

    Sutter, James K.; Jobe, Marcus; Crane, Elizabeth A.

    1995-01-01

    Recent developments in research on polyimides for high temperature applications have led to the synthesis of many new polymers. Among the criteria that determines their thermal oxidative stability, isothermal aging is one of the most important. Isothermal aging studies require that many experimental factors are controlled to provide accurate results. In this article we describe a statistical plan that compares the isothermal stability of several polyimide resins, while minimizing the variations inherent in high-temperature aging studies.

  20. Polarization and Piezoelectric Properties of a Nitrile Substituted Polyimide

    Science.gov (United States)

    Simpson, Joycelyn; Ounaies, Zoubeida; Fay, Catharine

    1997-01-01

    This research focuses on the synthesis and characterization of a piezoelectric (beta-CN)- APB/ODPA polyimide. The remanent polarization and piezoelectric d(sub 31) and g(sub 33) coefficients are reported to assess the effect of synthesis variations. Each of the materials exhibits a level of piezoelectricity which increases with temperature. The remanent polarization is retained at temperatures close to the glass transition temperature of the polyimide.

  1. Methods of preparing polyimides and artifacts composed thereof

    Science.gov (United States)

    Gagliani, John (Inventor); Lee, Raymond (Inventor); Wilcoxson, Anthony L. (Inventor)

    1984-01-01

    Methods of converting essentially unpolymerized precursors into polyimides in which the precursors are exposed to microwave radiation. Preheating, thermal post-curing, and other techniques may be employed to promote the development of optimum properties; and reinforcements can be employed to impart strength and rigidity to the final product. Also disclosed are processes for making various composite artifacts in which non-polymeric precursors are converted to polyimides by using the techniques described above.

  2. Heat-Resistant Composite Materials Based on Polyimide Matrix

    Directory of Open Access Journals (Sweden)

    Vitaly Sergeyevich Ivanov

    2016-12-01

    Full Text Available Heat-resistant composite materials with a polyimide-based binder were obtained in this paper. Composites were prepared with different content of single-wall carbon nanotubes (SWCNT and nanostructured silicon carbide, and polyimides coated carbon fibers woven into the cloth. Composite materials showed high values of thermostability and resistance to thermo-oxidative degradation, as well as good mechanical properties.

  3. Multi-step surface functionalization of polyimide based evanescent wave photonic biosensors and application for DNA hybridization by Mach-Zehnder interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Melnik, Eva [Health and Environment Department, Nano Systems, AIT Austrian Institute of Technology GmbH, Donau-City-Strasse 1, 1220 Vienna (Austria); Department of Analytical Chemistry, University of Vienna, Waehringer Strasse 38, 1090 Vienna (Austria); Bruck, Roman [Health and Environment Department, Nano Systems, AIT Austrian Institute of Technology GmbH, Donau-City-Strasse 1, 1220 Vienna (Austria); Hainberger, Rainer, E-mail: rainer.hainberger@ait.ac.at [Health and Environment Department, Nano Systems, AIT Austrian Institute of Technology GmbH, Donau-City-Strasse 1, 1220 Vienna (Austria); Laemmerhofer, Michael, E-mail: michael.laemmerhofer@univie.ac.at [Department of Analytical Chemistry, University of Vienna, Waehringer Strasse 38, 1090 Vienna (Austria)

    2011-08-12

    Highlights: {yields} We realize a biosensing platform for polyimide evanescent photonic wave sensors. {yields} We show that the surface functionalization via silanisation and biotinylation followed by streptavidin immobilization do not destroy or damage the thin polyimide film. {yields} A highly dense streptavidin layer enables the immobilisation of biotinylated ligands such as biotinylated ssDNA for the selective measurement of DNA hybridization. - Abstract: The process of surface functionalization involving silanization, biotinylation and streptavidin bonding as platform for biospecific ligand immobilization was optimized for thin film polyimide spin-coated silicon wafers, of which the polyimide film serves as a wave guiding layer in evanescent wave photonic biosensors. This type of optical sensors make great demands on the materials involved as well as on the layer properties, such as the optical quality, the layer thickness and the surface roughness. In this work we realized the binding of a 3-mercaptopropyl trimethoxysilane on an oxygen plasma activated polyimide surface followed by subsequent derivatization of the reactive thiol groups with maleimide-PEG{sub 2}-biotin and immobilization of streptavidin. The progress of the functionalization was monitored by using different fluorescence labels for optimization of the chemical derivatization steps. Further, X-ray photoelectron spectroscopy and atomic force microscopy were utilized for the characterization of the modified surface. These established analytical methods allowed to derive information like chemical composition of the surface, surface coverage with immobilized streptavidin, as well as parameters of the surface roughness. The proposed functionalization protocol furnished a surface density of 144 fmol mm{sup -2} streptavidin with good reproducibility (13.9% RSD, n = 10) and without inflicted damage to the surface. This surface modification was applied to polyimide based Mach-Zehnder interferometer

  4. Polyimide weld bonding for titanium alloy joints

    Science.gov (United States)

    Vaughan, R. W.; Kurland, R. M.

    1974-01-01

    Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system. A new polyimide laminating resin, BFBI/BMPM, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219 K (-65 F) to 561 K (+550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of the weld-through weld-bonding process for fabricating stringer stiffened skin panels.

  5. Molecular modeling of PMR-15 polyimide

    Science.gov (United States)

    Kokkada Ravindranath, Pruthul

    PMR-15 polyimide is a polymer that is used as a matrix in composites. These composites with PMR-15 matrices are called advanced polymer matrix composite that is abundantly used in the aerospace and electronics industries because of its high temperature resistivity. Apart from having high temperature sustainability, PMR-15 composites also display good thermal-oxidative stability, mechanical properties, processability and low costs, which makes it a suitable material for manufacturing aircraft structures. PMR-15 uses the reverse Diels-Alder (RDA) method for crosslinking which provides it with the groundwork for its distinctive thermal stability and a range of 280--300°C use temperature. Regardless of such desirable properties, this material has a number of limitations that compromises its application on a large scale basis. PMR-15 composites has been known to be very vulnerable to micro-cracking at inter and intra-laminar cracking. But the major factor that hinders its demand is PMR-15's carcinogenic constituent, methylene dianilineme (MDA), also a liver toxin. The necessity of providing a safe working environment during its production adds up to the cost of this material. In this study, Molecular Dynamics and Energy Minimization techniques are utilized to simulate a structure of PMR-15 at a given density of 1.324 g/cc and an attempt to recreate the polyimide to reduce the number of experimental testing and hence subdue the health hazards as well as the cost involved in its production. Even though this study does not involve in validating any mechanical properties of the model, it could be used in future for the validation of its properties and further testing for different properties like aging, microcracking, creep etc.

  6. Roughening of Polyimide Surface for Inkjet Printing by Plasma Etching Using the Polyimide Masked with Polystyrene Nanosphere Array.

    Science.gov (United States)

    Mun, Mu Kyeom; Park, Jin Woo; Ahn, Jin Ho; Kim, Ki Kang; Yeom, Geun Young

    2015-10-01

    Two key conditions are required for the application of fine-line inkjet printing onto a flexible substrate such as polyimide (PI): linewidth control during the inkjetting process, and a strong adhesion of the polyimide surface to the ink after the ink solidifies. In this study, the properties of a polyimide surface that was roughened through etching in a He/SF6 plasma, using a polystyrene nanosphere array as the etch mask, were investigated. The near-atmospheric-pressure plasma system of the He/SF6 plasma that was used exhibits two notable properties in this context: similar to an atmospheric-pressure plasma system, it can easily handle inline substrate processing; and, similar to a vacuum system, it can control the process gas environment. Through the use of plasma etching, the polyimide surface masked the 120-nm-diameter polystyrene nanospheres, thereby forming a roughened nanoscale polyimide surface. This surface exhibited not only a greater hydrophobicity--with a contact angle of about 150° for water and about 30° for silver ink, indicating better silver linewidth control during the silver inkjetting process--but also a stronger adhesion to the silver ink sprayed onto it when compared with the flat polyimide surface.

  7. Solution Based Deposition of Polyimide Ablators for NIF Capsules

    Energy Technology Data Exchange (ETDEWEB)

    Cook, R

    2002-07-11

    Between June 1997 and March 2002 Luxel Corporation was contracted to explore the possibility of preparing NIF scale capsules with polyimide ablators using solution-based techniques. This work offered a potential alternative to a vapor deposition approach talking place at LLNL. The motivation for pursuing the solution-based approach was primarily two-fold. First, it was expected that much higher strength capsules (relative to vapor deposition) could be prepared since the solution precursors were known to produce high strength films. Second, in applying the ablator as a fluid it was expected that surface tension effects would lead to very smooth surfaces. These potential advantages were offset by expected difficulties, primary among them that the capsules would need to be levitated in some fashion (for example acoustically) during coating and processing, and that application of the coating uniformly to thicknesses of 150 pm on levitated capsules would be difficult. Because of the expected problems with the coupling of levitation and coating, most of the initial effort was to develop coating and processing techniques on stalk-mounted capsules. The program had some success. Using atomizer spray techniques in which application of {approx}5 {micro}m fluid coatings were alternated with heating to remove solvent resulted in up to 70 {micro}m thick coatings that were reasonably smooth at short wavelengths, and showed only about a 1 {micro}m thickness variation over long wavelengths. More controlled deposition with an inkjet devise was also developed. However difficult technical problems remained, and these problems coupled with the relative success of the vapor deposition approach led to the termination of the solution-based work in 2002. What follows is a compilation of the progress reports submitted by Luxel for this work which spanned a number of separate contracts. The reports are arranged chronologically, the last report in the collection has a modest summary of what

  8. Development of a Multi-User Polyimide-MEMS Fabrication Process and its Application to MicroHotplates

    KAUST Repository

    Lizardo, Ernesto B.

    2013-05-08

    Micro-electro-mechanical systems (MEMS) became possible thanks to the silicon based technology used to fabricate integrated circuits. Originally, MEMS fabrication was limited to silicon based techniques and materials, but the expansion of MEMS applications brought the need of a wider catalog of materials, including polymers, now being used to fabricate MEMS. Polyimide is a very attractive polymer for MEMS fabrication due to its high temperature stability compared to other polymers, low coefficient of thermal expansion, low film stress and low cost. The goal of this thesis is to expand the Polyimide usage as structural material for MEMS by the development of a multi-user fabrication process for the integration of this polymer along with multiple metal layers on a silicon substrate. The process also integrates amorphous silicon as sacrificial layer to create free-standing structures. Dry etching is used to release the devices and avoid stiction phenomena. The developed process is used to fabricate platforms for micro-hotplate gas sensors. The fabrication steps for the platforms are described in detail, explaining the process specifics and capabilities. An initial testing of the micro-hotplate is presented. As the process was also used as educational tool, some designs made by students and fabricated with the Polyimide-MEMS process are also presented.

  9. Polymer−metal organic framework composite films as affinity layer for capacitive sensor devices

    NARCIS (Netherlands)

    Sachdeva, S.; Gravesteijn, Dirk J; Soccol, D.; Kapteijn, F.; Sudhölter, E.J.R.; Gascon, J.; Smet, de L.C.P.M.

    2016-01-01

    We report a simple method for sensor development using polymer-MOF composite films. Nanoparticles of NH2-MIL-53(Al) dispersed in a Matrimid polyimide were applied as a thin film on top of capacitive sensor devices with planar electrodes. These drop-cast films act as an affinity layer. Sensing

  10. Triptycene-based dianhydrides, polyimides, methods of making each, and methods of use

    KAUST Repository

    Ghanem, Bader

    2015-12-30

    A triptycene-based monomer, a method of making a triptycene-based monomer, a triptycene-based aromatic polyimide, a method of making a triptycene- based aromatic polyimide, methods of using triptycene-based aromatic polyimides, structures incorporating triptycene-based aromatic polyimides, and methods of gas separation are provided. Embodiments of the triptycene-based monomers and triptycene-based aromatic polyimides have high permeabilities and excellent selectivities. Embodiments of the triptycene-based aromatic polyimides have one or more of the following characteristics: intrinsic microporosity, good thermal stability, and enhanced solubility. In an exemplary embodiment, the triptycene-based aromatic polyimides are microporous and have a high BET surface area. In an exemplary embodiment, the triptycene-based aromatic polyimides can be used to form a gas separation membrane.

  11. Polyimide-etalon all-optical ultrasound transducer for high frequency applications

    Science.gov (United States)

    Sheaff, Clay; Ashkenazi, Shai

    2014-03-01

    We have enhanced our design for an all-optical high frequency ultrasound transducer consisting of a UV-absorbing polyimide film integrated into an etalon receiver operating in the NIR range. A dielectric stack having high NIR reflectivity and high UV transmittance was chosen as the first mirror for increased sensitivity and the allowance of polyimide as the etalon medium. A 13 ns, 0.7 μJ optical pulse at 355 nm and a continuous-wave NIR laser were focused onto the structure with a spot diameter of 120 and 35 μm, respectively. In receive mode the etalon had a noise-equivalent pressure of 4.1 kPa over a bandwidth of 5 - 50 MHz (0.61 Pa/√Hz ). The device generated a pressure of 270 kPa at a depth of 200 μm, and the -3 dB bandwidth of the emission extended from 27 to 60 MHz. In transmit/receive mode, the pulse-echo had a center frequency of 35 MHz with a -6 dB bandwidth of 49 MHz (140 %). Lastly, wire targets were imaged by scanning the UV spot to create a synthetic aperture of transmitters centered upon a single receiver.

  12. Fluorinated polyimide gate dielectrics for the advancing the electrical stability of organic field-effect transistors.

    Science.gov (United States)

    Baek, Yonghwa; Lim, Sooman; Yoo, Eun Joo; Kim, Lae Ho; Kim, Haekyoung; Lee, Seung Woo; Kim, Se Hyun; Park, Chan Eon

    2014-09-10

    Organic field-effect transistors (OFETs) that operated with good electrical stability were prepared by synthesizing fluorinated polyimide (PI) gate dielectrics based on 6FDA-PDA-PDA PI and 6FDA-CF3Bz-PDA PI. 6FDA-PDA-PDA PI and 6FDA-CF3Bz-PDA PI contain 6 and 18 fluorine atoms per repeat unit, respectively. These fluorinated polymers provided smooth surface topographies and surface energies that decreased as the number of fluorine atoms in the polymer backbone increased. These properties led to a better crystalline morphology in the semiconductor film grown over their surfaces. The number of fluorine atoms in the PI backbone increased, the field-effect mobility improved, and the threshold voltage shifted toward positive values (from -0.38 to +2.21 V) in the OFETs with pentacene and triethylsilylethynyl anthradithiophene. In addition, the highly fluorinated polyimide dielectric showed negligible hysteresis and a notable gate bias stability under both a N2 environment and ambient air.

  13. Correlation between surface free energy and anchoring energy of 6CHBT on polyimide surface

    Science.gov (United States)

    Borycki, Jerzy; Okulska-Bozek, Malgorzata; Kedzierski, Jerzy; Kojdecki, Marek A.

    2002-06-01

    Polyimides were prepared in the classical two-step method via poly(amic acids). Poly(amic acids) were obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'- (hexafluoroisopropylidene)diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA), 3,3',4,4'- diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'- oxydiphthalic anhydride (ODPA) and amines 4,4'-oxydianiline (ODA), 1,3-phenylenediamine (MPD), 1,4-phenylenediamine (PPD), 4,4'-diaminodiphenylmethane (MDA), 4,4'- ethylenedianiline (DAB), 2,4,6-trimethyl-1,3- phenylenediamine (TMPD), 4-methyl-1,3-phenylenediamine (MMPD) and 2,3,5,6-tetramethyl-1,4-phenylenediamine (DAD) in dimethylformamide. The indium tin oxide (ITO)-glass plates were spin-coated with the poly(amic acids) solutions and dried. A thermal imidization process was then carried out at 250 degree(s)C for 4 h. In this study the anchoring energies of 6CHBT molecules were evaluated on rubbing aligning layers of PI films. The polar anchoring energy coefficient was determined by wedge cell method. The surface free energy and its components of polyimide layers were determined by measuring the contact angles of water, ethylene glycol, formamide and diiodomethane drops on the rubbing polymer surfaces. The Lifshitz-van der Waals and acidic-basic components of surface free energies were found from van Oss equation.

  14. Coupling Between Microstrip Lines and Finite Ground Coplanar Lines Embedded in Polyimide Layers for 3D-MMICs on Silicon

    Science.gov (United States)

    Ponchak, G. E.; Bushyager, N.; Papapolymerou, J.; Tentzeris, E. M.; Laskar, J.

    2002-01-01

    Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si/SiGe monolithic microwave/mm-wave integrated circuits on CMOS (low resistivity) Si wafers. It is expected that these circuits will replace the ones fabricated on GaAs and reduce the overall system cost. However, the closely spaced transmission lines that are required for a high-density circuit environment are susceptible to high levels of cross-coupling, which degrades the overall circuit performance. In this paper, theoretical and experimental results on coupling and ways to reduce it are presented for two types of transmission lines: a) the microstrip line and b) the Finite Ground Coplanar (FGC) line. For microstrip lines it is shown that a fence of metalized via-holes can significantly reduce coupling, especially in the case when both lines are on the same polyimide layer or when the shielding structure extends through several polyimide layers. For closely spaced microstrip lines, coupling is lower for a metal filled trench shield than a via-hole fence. Coupling amongst microstrip lines is dependent on the ratio of line separation to polyimide thickness and is primarily due to magnetic fields. For FGC lines it is shown that they have in general low coupling that can be reduced significantly when there is even a small gap between the ground planes of each line. FGC lines have approximately 8 dB lower coupling than coupled coplanar waveguides (CPW). In addition, forward and backward characteristics of the FGC lines do not resemble those of other transmission lines such as microstrip. Therefore, the coupling mechanism of the FGC lines is different compared to thin film microstrip lines.

  15. Comparisons of Polyhedral Oligomeric Silsesquioxane (POSS) Polyimides as Space-Survivable Materials (Postprint)

    Science.gov (United States)

    2006-11-15

    AFRL/PRSM); Vandana Vij (ERC); 5d. PROJECT NUMBER DARPA443 Timothy Minton & Amy Brunsvold (Montana State Univ.); Michael Wright, Brian Petteys...8.75 % Si8O11 MC-POSS PI, and silica-coated Kapton HN® (provided by Astral Technology Unlimited, Inc. Lot No. 00625-007, with a 130 nm SiO2 coating...images of results from a self-passivation experiment. (a.) Kapton H®, (b.) SiO2 coated Kapton HN® (Provided by Astral Industries Inc.), and (c.) 8.75 wt

  16. Survey of sulfonated polyimide membrane as a good candidate for nafion substitution in fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Akbarian-Feizi, Leila; Mehdipour-Ataei, Shahram; Yeganeh, Hamid [Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran)

    2010-09-15

    Studies in fuel cell membranes show that modification of polyimides by introduction of aliphatic linkages in the structure of sulfonated copolyimides, synthesis of branched/crosslinked sulfonated polyimides, and semi and fully interpenetrating polymer networks of sulfonated polyimides restrain suitable potential for Nafion substitution. (author)

  17. Shelf Life of PMR Polyimide Monomer Solutions and Prepregs Extended

    Science.gov (United States)

    Alston, William B.; Scheiman, Daniel A.

    2000-01-01

    PMR (Polymerization of Monomeric Reactants) technology was developed in the mid-1970's at the NASA Glenn Research Center at Lewis Field for fabricating high-temperature stable polyimide composites. This technology allowed a solution of polyimide monomers or prepreg (a fiber, such as glass or graphite, impregnated with PMR polyimide monomers) to be thermally cured without the release of volatiles that cause the formation of voids unlike the non-PMR technology used for polyimide condensation type resins. The initial PMR resin introduced as PMR 15 is still commercially available and is used worldwide by aerospace industries as the state-of-the-art resin for high-temperature polyimide composite applications. PMR 15 offers easy composite processing, excellent composite mechanical property retention, a long lifetime at use temperatures of 500 to 550 F, and relatively low cost. Later, second-generation PMR resin versions, such as PMR II 50 and VCAP 75, offer improvements in the upper-use temperature (to 700 F) and in the useful life at temperature without major compromises in processing and property retention but with significant increases in resin cost. Newer versions of nontoxic (non-methylene dianiline) PMR resins, such as BAX PMR 15, offer similar advantages as originally found for PMR 15 but also with significant increases in resin cost. Thus, the current scope of the entire PMR technology available meets a wide range of aeronautical requirements for polymer composite applications.

  18. A flexible insulator of a hollow SiO2 sphere and polyimide hybrid for flexible OLEDs.

    Science.gov (United States)

    Kim, Min Kyu; Kim, Dong Won; Shin, Dong Wook; Seo, Sang Joon; Chung, Ho Kyoon; Yoo, Ji Beom

    2015-01-28

    The fabrication of interlayer dielectrics (ILDs) in flexible organic light-emitting diodes (OLEDs) not only requires flexible materials with a low dielectric constant, but also ones that possess the electrical, thermal, chemical, and mechanical properties required for optimal device performance. Porous polymer-silica hybrid materials were prepared to satisfy these requirements. Hollow SiO2 spheres were synthesized using atomic layer deposition (ALD) and a thermal calcination process. The hybrid film, which consists of hollow SiO2 spheres and polyimide, shows a low dielectric constant of 1.98 and excellent thermal stability up to 500 °C. After the bending test for 50 000 cycles, the porous hybrid film exhibits no degradation in its dielectric constant or leakage current. These results indicate that the hybrid film made up of hollow SiO2 spheres and polyimide (PI) is useful as a flexible insulator with a low dielectric constant and high thermal stability for flexible OLEDs.

  19. A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser

    Directory of Open Access Journals (Sweden)

    Tianxian Feng

    2016-11-01

    Full Text Available We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP nanosheets were prepared via a liquid exfoliation approach exploiting N-methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI, a piece of BP–PI film was obtained after evaporating the mixture in a petri dish. The BP–PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser to realize passive Q-switched operations. The repetition rate of the Q-switched laser increased from 5.73 kHz to 31.07 kHz when the laser pump was enhanced from 31.78 mW to 231.46 mW. Our results show that PI is an excellent host material to protect BP from oxidation, and the BP–PI film can act as a promising nonlinear optical device for laser applications.

  20. A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser.

    Science.gov (United States)

    Feng, Tianxian; Mao, Dong; Cui, Xiaoqi; Li, Mingkun; Song, Kun; Jiang, Biqiang; Lu, Hua; Quan, Wangmin

    2016-11-11

    We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP) nanosheets were prepared via a liquid exfoliation approach exploiting N-methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI), a piece of BP-PI film was obtained after evaporating the mixture in a petri dish. The BP-PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser to realize passive Q-switched operations. The repetition rate of the Q-switched laser increased from 5.73 kHz to 31.07 kHz when the laser pump was enhanced from 31.78 mW to 231.46 mW. Our results show that PI is an excellent host material to protect BP from oxidation, and the BP-PI film can act as a promising nonlinear optical device for laser applications.

  1. Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

    Science.gov (United States)

    Naito, Kimiyoshi

    2014-09-01

    The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4'-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.

  2. Polyimides Derived from Novel Asymmetric Dianhydrides

    Science.gov (United States)

    Chuang, Chun-Hua (Inventor)

    2012-01-01

    This invention relates to the compositions and processes for preparing thermoset and thermoplastic polyimides derived from novel asymmetrical dianhydrides: specifically 2,3,3',4' benzophenone dianhydride (a-BTDA), and 3,4'-(hexafluoroisopropylidene)diphthalic anhydride (a-6FDA). The a-BTDA anhydride is prepared by Suzuki coupling with catalysts from a mixed anhydride of 3,4-dimethylbenzoic acid or 2,3-dimethylbenzoic acid with 2,3-dimethylphenylboronic acid or 3,4-dimethylphenylboronic acid respectively, to form 2,3,3',4'-tetramethylbenzophenone which is oxidized to form 2,3,3',4'-benzophenonetetracarboxylic acid followed by cyclodehydration to obtain a-BTDA. The a-6FDA is prepared by nucleophilic triflouoromethylation of 2,3,3',4'-tetramethylbenzophenone with trifluoromethyltrimethylsilane to form 3,4'-(trifluoromethylmethanol)-bis(o-xylene) which is converted to 3,4'-(hexafluoroisopropylidene-bis(o-xylene). The 3,4'-(hexafluoroisopropylidene)-bis(o-xylene) is oxidized to the corresponding tetraacid followed by cyclodehydration to yield a-6FDA.

  3. Thermal assisted ion shrinkage (TAIS) of fluorinated polyimide for optical telecommunication devices

    Science.gov (United States)

    Trigaud, T.; Moliton, J. P.; Quillat, M.; Chiron, D.

    1999-06-01

    In the framework of the development of low cost optical devices for telecommunications, here is studied the shrinkage of 6FDA-ODA polyimide films by ion irradiation as a function of five parameters: the ion fluence, the ion fluence rate, the ion energy, the ion nature and the target temperature. In the 30-350 keV energy range for impinging ions, the shrinkage remains constant whatever the tested fluence rate is. An upper limit appears for fluences above 10 16 ions cm -2. The etching is linearly dependent on the ion beam energy and reaches a maximum around 1 μm by thermal assisted ion shrinkage (TAIS) with Na + irradiations.

  4. Self-Lubricating Polytetrafluoroethylene/Polyimide Blends Reinforced with Zinc Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Liwen Mu

    2015-01-01

    Full Text Available ZnO nanoparticle reinforced polytetrafluoroethylene/polyimide (PTFE/PI nanocomposites were prepared and their corresponding tribological and mechanical properties were studied in this work. The influences of ZnO loading, sliding load, and velocity on the tribological properties of ZnO/PTFE/PI nanocomposites were systematically investigated. Results reveal that nanocomposites reinforced with 3 wt% ZnO exhibit the optimal tribological and mechanical properties. Specifically, the wear loss decreased by 20% after incorporating 3 wt% ZnO compared to unfilled PTFE/PI. Meanwhile, the impact strength, tensile strength, and elongation-at-break of 3 wt% ZnO/PTFE/PI nanocomposite are enhanced by 85, 5, and 10% compared to pure PTFE/PI blend. Microstructure investigation reveals that ZnO nanoparticles facilitate the formation of continuous, uniform, and smooth transfer film and thus reduce the adhesive wear of PTFE/PI.

  5. Effect of Branching on Rod-coil Polyimides as Membrane Materials for Lithium Polymer Batteries

    Science.gov (United States)

    Meador, Mary Ann B.; Cubon, Valerie A.; Scheiman, Daniel A.; Bennett, William R.

    2003-01-01

    This paper describes a series of rod-coil block co-polymers that produce easy to fabricate, dimensionally stable films with good ionic conductivity down to room temperature for use as electrolytes for lithium polymer batteries. The polymers consist of short, rigid rod polyimide segments, alternating with flexible, polyalkylene oxide coil segments. The highly incompatible rods and coils should phase separate, especially in the presence of lithium ions. The coil phase would allow for conduction of lithium ions, while the rigid rod phase would provide a high degree of dimensional stability. An optimization study was carried out to study the effect of four variables (degree of branching, formulated molecular weight, polymerization solvent and lithium salt concentration) on ionic conductivity, glass transition temperature and dimensional stability in this system.

  6. Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

    Science.gov (United States)

    Vered, R.; Grossman, E.; Lempert, G. D.; Lifshitz, Y.

    1994-01-01

    A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

  7. High organosolubility and optical transparency of novel polyimides derived from 2',7'-bis(4-amino-2-trifluoromethylphenoxy)-spiro (fluorene-9,9'-xanthene)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shujiang [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Key Laboratory of Specially Functional Materials, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Bu Qianqian [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Li Yanfeng, E-mail: liyf@lzu.edu.cn [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Gong Chenliang; Xu Xiangyang; Li Hui [State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2011-08-15

    Highlights: {yields} In this study, we synthesized a series of novel polyimides from 2',7'-bis(4-amino-2-tri fluoromethylphenoxy)-spiro(fluorene-9,9'-xanthene). {yields} The resulting polyimides could be cast into flexible and strong films with high optical transparency, excellent thermal stability and low dielectric constants. - Abstract: A novel spiro(fluorene-9,9'-xanthene) skeleton bis(ether amine) monomer, 2',7'-bis(4-amino-2-trifluoromethylphenoxy)-spiro(fluorene-9,9'-xanthene), was prepared through a simple acid-catalyzed condensation reaction of 9-fluorenone with resorcinol to form the spiro framework through an sp{sup 3} carbon atom. Subsequent nucleophilic substitution reaction of spiro[fluorene-9,9'-(2',7'-dihydroxyxanthene)] with 2-chloro-5-nitrobenzotrifluoride in the presence of potassium carbonate in N,N-dimethylacetamide, was followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new polyimides were synthesized from the diamine with various commercially available aromatic tetracarboxylic dianhydrides via a conventional two-stage process with the thermal or chemical imidization of the poly(amic acid) precursors. Most of the polyimides obtained from both routes were soluble in many organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide and m-cresol. All the polyimides could afford transparent, flexible, and strong films with low moisture absorptions of 0.35-0.64% and low dielectric constants of 2.63-3.09 at 1 kHz. Thin films of these polyimides showed an UV-vis absorption cutoff wavelength at 356-384 nm, and those of polyimides from 4,4'-oxydiphthalic dianhydride and 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) were essentially colorless. The polyimides exhibited excellent thermal stability, with decomposition temperatures (at 10% weight loss) above 540 deg. C in both air and nitrogen atmospheres and glass transition temperatures (T

  8. Thermal Properties of Polyimide Composites with Nanostructured Silicon Carbide

    Directory of Open Access Journals (Sweden)

    Alyona Igorevna Wozniak

    2016-12-01

    Full Text Available A series of polyimide composites reinforced with different loadings of silicon carbide (SiC nanoparticles are prepared by in-situ polymerization technique. The polyimide (PI matrix resin is derived from 4,4’-oxydianiline (4,4’-ODA and pyromelliticdianhydride (PMDA. The dispersions of SiC nanoparticles are prepared via ultrasonic irradiation or mechanical homogenization. In this method, the SiC nanoparticles are dispersed in diamine solution followed by polymerization with dianhydride. The composites obtained under sonication were found to have lower thermal properties than composites prepared under homogenization.

  9. Evaluation of Nanoclay Exfoliation Strategies for Thermoset Polyimide Nanocomposite Systems

    Science.gov (United States)

    Ginter, Michael J.; Jana, Sadhan C.; Miller, Sandi G.

    2007-01-01

    Prior works show exfoliated layered silicate reinforcement improves polymer composite properties. However, achieving full clay exfoliation in high performance thermoset polyimides remains a challenge. This study explores a new method of clay exfoliation, which includes clay intercalation by lower molecular weight PMR monomer under conditions of low and high shear and sonication, clay treatments by aliphatic and aromatic surfactants, and clay dispersion in primary, higher molecular weight PMR resin. Clay spacing, thermal, and mechanical properties were evaluated and compared with the best results available in literature for PMR polyimide systems.

  10. Development of autoclave moldable addition-type polyimides

    Science.gov (United States)

    Vaughan, R. W.; Jones, R. J.; Orell, M. K.; Zakrzewski, G. A.

    1976-01-01

    Chemistry and processing modifications of the poly(Diels Alder) polyimide (PDA) resin were performed to obtain structural composites suitable for 589 K (600 F) service. This work demonstrated that the PDA resin formulation is suitable for service at 589 K (600 F) for up to 125 hours when used in combination with Hercules HTS graphite fiber. Sandwich panels were autoclave molded using PDA/HTS skins and polyimide/glass honeycomb core. Excellent adhesion between honeycomb core and the facing skins was demonstrated. Fabrication ease was demonstrated by autoclave molding three-quarter scale YF-12 wing panels.

  11. Polyimides with improved operational by properties

    Institute of Scientific and Technical Information of China (English)

    Oranova; T.; I.; Mamisheva; I.M.

    2005-01-01

    One of directions of basic researches in the field of chemical process engineerings is making new polymeric materials for electronics and aviation technique distinguished by boosted production characteristics.The value of aromatic polyimides (PI) as industrial thermally sound polymers is well-known. However alongside with a complex of valuable properties they have also series of shortages: high temperatures and difficulty of reaching of 100% conversion at ring formation polyamic acids (PAA) and their instability in time, low stability to hydrolysis, poor adhesion to line of substratums etc. all this in some cases restricts or makes to impossible application PI in practice.The complex examinations, spent by us, the solid-phase of thermal cyclyzation PAA and its model junctions have reduced in an establishment of correlation associations between a degree and velocity of ring-formation, thermal stability and reagent resistance, stregth that has allowed to govern process of deriving PI with a necessary level of production characteristics. Use of some components, for example, heterocyclic basic amines-azoles, promotes acceleration and lowering of a temperature band of ring-formation PAA, and also magnification of a degree of ring-formation, that reduces in a considerable raise thermal and chemical resistance, mechanical and dielectric parameters and insulant properties which are not varying at long-lived operation.The modes of deriving of various materials designed on the basis of industrial PAA of a lacquer consisting in introduction of azoles, plasticizing and adhesion components. It is shown, that the coats obtained from modified polymers, have boosted adhesion, high thermal, mechanical, insulant and other properties maintained in requirements of climatic trials.

  12. Influence of commercially available polyimide and formation conditions on the performance and structure of asymmetric polyimide organic solvent nanofiltration membranes

    OpenAIRE

    Lopes, Mafalda Pessoa

    2009-01-01

    Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Química e Bioquímica This work covers experimental and theoretical research related to the impact of the polymer structure of commercially available polyimide and polyetherimides as well as the formation conditions on the performance and structure of polyimide Organic Solvent Nanofiltration membranes. The influence in some membrane formation parame...

  13. Synthesis and properties of reprocessable sulfonated polyimides cross-linked via acid stimulation for use as proton exchange membranes

    Science.gov (United States)

    Zhang, Boping; Ni, Jiangpeng; Xiang, Xiongzhi; Wang, Lei; Chen, Yongming

    2017-01-01

    Cross-linked sulfonated polyimides are one of the most promising materials for proton exchange membrane (PEM) applications. However, these cross-linked membranes are difficult to reprocess because they are insoluble. In this study, a series of cross-linkable sulfonated polyimides with flexible pendant alkyl side chains containing trimethoxysilyl groups is successfully synthesized. The cross-linkable polymers are highly soluble in common solvents and can be used to prepare tough and smooth films. Before the cross-linking reaction is complete, the membranes can be reprocessed, and the recovery rate of the prepared films falls within an acceptable range. The cross-linked membranes are obtained rapidly when the cross-linkable membranes are immersed in an acid solution, yielding a cross-linking density of the gel fraction of greater than 90%. The cross-linked membranes exhibit high proton conductivities and tensile strengths under hydrous conditions. Compared with those of pristine membranes, the oxidative and hydrolytic stabilities of the cross-linked membranes are significantly higher. The CSPI-70 membrane shows considerable power density in a direct methanol fuel cell (DMFC) test. All of these results suggest that the prepared cross-linked membranes have great potential for applications in proton exchange membrane fuel cells.

  14. A method for fabricating a micro-structured surface of polyimide with open and closed pores

    CERN Document Server

    Ma, Yong-Won; Ahn, Seokyoung; Shin, Bo Sung

    2016-01-01

    A new approach for fabricating open and closed porous structures based on laser processing is presented. Liquid polyimide (PI) was mixed with azodicarbonamide (ADC, ADA) which is a chemical blowing agent (CBA) and mixture was pre-cured in order to fabricate solid PI film. Porous PI was prepared by irradiating PI film mixed with azodicarbonamide. The PI film with azodicarbonamide was etched by laser ablation, and the CBA was decomposed by heat induced by the absorbed laser energy. The higher the laser beam irradiation, the more pores were fabricated due to the resulting increase in CBA decomposition from 27 mJ/cm2 to 40 mJ/cm2 per single pulse. Higher fluence at about 50 mJ/cm2 resulted in fewer and larger open pores, which were formed by the coalescence of small pores. In contrast, a closed porous structure was fabricated at a fluence of less than 1 mJ/cm2 because PI was barely etched. The proposed method can be sued to create open and closed micro porous structures selectively, and is not limited to thermose...

  15. A method for fabricating a micro-structured surface of polyimide with open and closed pores

    Science.gov (United States)

    Ma, Yong-Won; Oh, Jae Yong; Ahn, Seokyoung; Shin, Bo Sung

    2016-08-01

    A new approach for fabricating open and closed porous structures based on laser processing is presented. Liquid polyimide (PI) was mixed with azodicarbonamide which is a chemical blowing agent (CBA), and the mixture was spin-coated and pre-cured in order to fabricate solid PI films. Porous PI was prepared by irradiating PI films mixed with azodicarbonamide. The PI film with azodicarbonamide was etched by using laser ablation, and the azodicarbonamide was decomposed due to the heat induced by the absorbed laser energy. At higher laser beam irradiation, more pores were fabricated due to the resulting increase in the CBA decomposition from 27 mJ/cm2 to 40 mJ/cm2 per single pulse. A fluence of about 50 mJ/cm2 resulted in fewer and larger open pores, which were formed by the coalescence of small pores. In contrast, a closed porous structure was fabricated at a fluence of less than 1 mJ/cm2 because PI was barely etched. The proposed method can be used to create open and closed porous structures selectively and is not limited to thermosetting polymers, but is also effective with thermoplastic polymers.

  16. Microfabrication of plastic-PDMS microfluidic devices using polyimide release layer and selective adhesive bonding

    Science.gov (United States)

    Wang, Shuyu; Yu, Shifeng; Lu, Ming; Zuo, Lei

    2017-05-01

    In this paper, we present an improved method to bond poly(dimethylsiloxane) (PDMS) with polyimide (PI) to develop flexible substrate microfluidic devices. The PI film was separately fabricated on a silicon wafer by spin coating followed by thermal treatment to avoid surface unevenness of the flexible substrate. In this way, we could also integrate flexible substrate into standard micro-electromechanical systems (MEMS) fabrication. Meanwhile, the adhesive epoxy was selectively transferred to the PDMS microfluidic device by a stamp-and-stick method to avoid epoxy clogging the microfluidic channels. To spread out the epoxy evenly on the transferring substrate, we used superhydrophilic vanadium oxide film coated glass as the transferring substrate. After the bonding process, the flexible substrate could easily be peeled off from the rigid substrate. Contact angle measurement was used to characterize the hydrophicity of the vanadium oxide film. X-ray photoelectron spectroscopy analysis was conducted to study the surface of the epoxy. We further evaluated the bonding quality by peeling tests, which showed a maximum bonding strength of 100 kPa. By injecting with black ink, the plastic microfluidic device was confirmed to be well bonded with no leakage for a day under 1 atm. This proposed versatile method could bond the microfluidic device and plastic substrate together and be applied in the fabrication of some biosensors and lab-on-a-chip systems.

  17. Moisture absorption analysis of high performance polyimide adhesive

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Bhowmik, S.; Ernst, L.J.

    2011-01-01

    The high temperature resistant polymers and metal composites are used widely in aviation, space, automotive and electronics industry. The high temperature resistant polymers and metals are joined together using high temperature adhesives. Polyimide and epoxy adhesives that can withstand high tempera

  18. The technology of microcircuit assembly on flexible polyimide substrate

    Directory of Open Access Journals (Sweden)

    Plis N. I.

    2010-10-01

    Full Text Available The research is devoted to technology of microcircuit assembly on flexible polyimide substrate. It is proved that such microcircuits provide high reliability and have advantage over other IC models when applied in hermetic micro-assemblies in microelectronic devices that operate under high accelerations, shocks and strong radiation.

  19. Mechanism of electrical conductivity in an irradiated polyimide

    Science.gov (United States)

    Ries, H. R.; Harries, W. L.; Long, S. A. T.; Long, E. R., Jr.

    1989-01-01

    A polyimide was exposed to 1.0 MeV electron radiation. The radiation-induced radical density and dc conductivity were measured at various post-irradiation times. The radiation-induced radical density was found to be correlated to the increased dc conductivity through a hopping model of conductivity. The post-irradiation radical species were identified.

  20. Low-void polyimide resins for autoclave processing

    Science.gov (United States)

    Jones, R. J.; Vaughan, R. W.

    1972-01-01

    Development of an advanced A-type polyimide, which can be used to produce autoclave molded, low-void content composites suitable for use at temperatures up to 316 C is reported. It consists of a mixture of methyl nadic anhydride, an 80:20 molar ratio of methylene dianaline and thiodianilene, and pyromellitic dianhydride.

  1. Commercialization of LARC (TradeMark) -SI Polyimide Technology

    Science.gov (United States)

    Bryant, Robert G.

    2011-01-01

    LARC(TradeMark)-SI, Langley Research Center- Soluble Imide, was developed in 1992, with the first patent issuing in 1997, and then subsequent patents issued in 1998 and 2000. Currently, this polymer has been successfully licensed by NASA, and has generated revenues, at the time of this reporting, in excess of $1.4 million. The success of this particular polymer has been due to many factors and many lessons learned to the point that the invention, while important, is the least significant part in the commercialization of this material. Commercial LARC(TradeMark)-SI is a polyimide composed of two molar equivalents of dianhydrides: 4,4 -oxydiphthalic anhydride (ODPA), and 3,3 ,4,4 -biphenyltetracarboxylic dianhydride (BPDA) and 3,4 -oxydianiline (3,4 -ODA) as the diamine. The unique feature of this aromatic polyimide is that it remains soluble after solution imidization in high-boiling, polar aprotic solvents, even at solids contents of 50-percent by weight. However, once isolated and heated above its T(sub g) of 240 C, it becomes insoluble and exhibits high-temperature thermoplastic melt-flow behavior. With these unique structure property characteristics, it was thought this would be an advantage to have an aromatic polyimide that is both solution and melt processable in the imide form. This could potentially lead to lower cost production as it was not as equipment- or labor-intensive as other high-performance polyimide materials that either precipitate or are intractable. This unique combination of properties allowed patents with broad claim coverage and potential commercialization. After the U.S. Patent applications were filed, a Small Business Innovation Research (SBIR) contract was awarded to Imtec, Inc. to develop and supply the polyimide to NASA and the general public. Some examples of demonstration parts made with LARC(TradeMark)-SI ranged from aircraft wire and multilayer printed-circuit boards, to gears, composite panels, supported adhesive tape, composite

  2. Natural Gas Sweetening by Ultra-Microporous Polyimides Membranes

    KAUST Repository

    Alghunaimi, Fahd

    2017-05-01

    Most natural gas fields in Saudi Arabia contain around 10 mol.% carbon dioxide. The present technology to remove carbon dioxide is performed by chemical absorption, which has many drawbacks. Alternatively, membrane-based gas separation technology has attracted great interest in recent years due to: (i) simple modular design, (ii) potential cost effectiveness, (iii) ease of scale-up, and (iv) environmental friendliness. The state-of-the-art membrane materials for natural gas sweetening are glassy cellulose acetate and polyimide, which were introduced in the 1980s. In the near future, the kingdom is planning to boost its production of natural gas for power generation and increase the feedstock for new petrochemical plants. Therefore, the kingdom and worldwide market has an urgent need for better membrane materials to remove carbon dioxide from raw natural gas. The focus of this dissertation was to design new polyimide membrane materials for CO2/CH4 separation exhibiting high permeability and high selectivity relative to the standard commercial materials tested under realistic mixed-gas feed conditions. Furthermore, this study provided a fundamental understanding of structure/gas transport property relationships of triptycene-based PIM-polyimides. Optimally designed intrinsically microporous polyimide (PIM-PIs) membranes in this work exhibited drastically increased CO2/CH4 selectivities of up to ~75. In addition, a novel triptycene-based hydroxyl-containing polyimide (TDA1-APAF) showed 5-fold higher permeabilities over benchmark commercial materials such as cellulose acetate. Furthermore, this polyimide had a N2/CH4 selectivity of 2.3, thereby making it possible to simultaneously treat CO2- and N2-contaminated natural gas. Also, TDA1-APAF showed a CO2 permeability of 21 Barrer under binary 1:1 CO2/CH4 mixed-gas feed with a selectivity of 72 at a partial CO2 pressure of 10 bar which are significantly better than cellulose triacetate. These results suggest that TDA1

  3. Polyimide/Carboxylated Multiple-walled Carbon Nanotubes Nanocomposites Films Fabricated by in situ Polymerization%原位聚合制备羧酸化多壁碳纳米管/聚酰亚胺纳米复合薄膜

    Institute of Scientific and Technical Information of China (English)

    彭思敏; 王世敏; 万丽; 董兵海; 潘攀

    2011-01-01

    Polyimide/carboxylated multiple-walled carbon nanotubes (PI/MWNTs-COOH) nanocompos-ites were synthesized by in situ polymerization using4,4' -oxydianilline (ODA) , pyromellitic dianhydride (PMDA) and MWNTs-COOH which was prepared by microwave-assisted oxidation. Raman, FT-IR spec-troscopy and TEM images confirmed that the surfaces of the functionalized MWNTs possessed the polar groups of carboxyl and hydroxyl groups. A homogeneous disperson of MWNTs-COOH was achieved in polyimide matrix as evidenced by SEM characterizations, while the structure of the polymide and multiple-walled carbon nanotubes was stable in the preparation process demonstrated by FT-IR and XRD spec-troscopy. According to the DMA, DSC and TGA analysis, the resultant PI/MWNTs-COOH nanocompos-ites both exhibit excellent thermal resistance, and have stronger thermal stability than pure polyimide due to the strong interfacial interaction between the MWNTs-COOH and polyimide matrix, which is favorable for practical use in heat-resisting material.%以微波辅助液相氧化法制备羧酸化多壁碳纳米管,并以4,4’-二氨基二苯醚(ODA)、羧酸化多壁碳纳米管(MWNTs-COOH)与均苯四甲酸二酐(PMDA)为原料,原位聚合制备羧酸化多壁碳纳米管/聚酰亚胺纳米(PI/MWNTs-COOH)复合薄膜.通过拉曼光谱(Raman)、透射电镜(TEM),傅里叶红外光谱(FT-IR)证实修饰后的碳纳米管表面接上-COOH等极性基团;扫描电镜(SEM)图片显示出MWNTs-COOH能均一分散在聚酰亚胺基体中,并通过傅里叶红外光谱(FT-IR)和X射线衍射光谱(XRD)证明聚酰亚胺与多壁碳纳米管的结构在薄膜制备过程中很稳定.通过动态力学(DMA)和差示扫描量热(DSC)分析发现薄膜的耐热性较好,且通过热失重(TGA)测试发现纳米复合材料的热稳定性比纯聚酰亚胺要高,主要是因为修饰后的多壁碳纳米管和聚酰亚胺基底之间强烈的相互作用,这就有利于耐热材料的实际应用.

  4. The German Joint Project "Flexible CIGSe Thin Film Solar Cells for Space Flight

    Science.gov (United States)

    Zajac, Kai; Brunner, Sebastian; John, Ralf; Kaufmann, Christian A.; Otte, Karsten; Rahm, Andreas; Kessler, Friedrich

    2008-09-01

    The purpose of the presented joint project is the development and verification of a flexible, lightweight and highly efficient Cu(In,Ga)Se2 (CIGSe) thin film solar cell technology on polyimide foil substrate for use in space. Due to the worldwide leading present German activities on the field of chalcopyrite based thin film solar cells a harmonisation of resources shall push this development. Furthermore, this project supports the European Space Agency (ESA) program for the development of thin film solar cell technology for space applications. Recent results of substrate evaluation and CIGSe solar cell and module manufacturing on polyimide foil substrate are presented.

  5. Magnetic Field Effect Transistors

    Science.gov (United States)

    1990-07-01

    apparent damage to either the Ultem 1000 (polyetherimide) or Kapton substrates. The resistivity of the palladium films (ɘ.1 um) suggests that the... Ultem 1000 is similar to that of bulk palladium. Film thickness was determined from XES and WDS, and the correlation of the data to model scattering...calculations are good. Scratches through the films on Kapten and Ultem 1000 did not reveal the presence of any obvious damage to the polyimide films and

  6. Conversion of Langmuir–Blodgett monolayers and bilayers of poly(amic acid) through polyimide to graphene

    Science.gov (United States)

    Jo, Hye Jin; Lyu, Ji Hong; Ruoff, Rodney S.; Lim, Hyunseob; In Yoon, Seong; Jeong, Hu Young; Shin, Tae Joo; Bielawski, Christopher W.; Shin, Hyeon Suk

    2017-03-01

    Various solid carbon sources, particularly poly(methyl methacrylate), have been used as precursors to graphene. The corresponding growth process generally involves the decomposition of the solids to hydrocarbon gases followed by their adsorption on metallic substrates (e.g., Cu). We report a different approach that uses a thermally-resistant polyimide (PI) as a carbon precursor. Langmuir–Blodgett films of poly(amic acid) (PAA) were transferred to copper foils and then converted to graphene via a PI intermediate. The Cu foil substrate was also discovered to facilitate the orientation of aromatic moieties upon carbonization process of the PI. As approximately 50% of the initial quantity of the PAA was found to remain at 1000 °C, thermally-stable polymers may reduce the quantity of starting material required to prepare high quality films of graphene. Graphene grown using this method featured a relatively large domain size and an absence of adventitious adlayers.

  7. Plasticization-resistant hollow fiber membranes for CO2/CH4 separation based on a thermally crosslinkable polyimide

    KAUST Repository

    Chen, Chien-Chiang

    2011-10-01

    Decarboxylation-induced thermal crosslinking has been demonstrated to be effective for stabilizing membranes against plasticization in dense films. This study extends this promising crosslinking approach from dense films to industrially relevant asymmetric hollow fiber membranes. Crosslinkable asymmetric hollow fiber membranes were spun from a carboxylic acid containing polyimide, 6FDA-DAM:DABA. Dope and spinning conditions were optimized to obtain fibers with a defect-free selective skin layer. It is found that slightly defective fibers suffered severe selectivity loss after thermal crosslinking, suggesting that defect-free property is essential to the performance of the resulting crosslinked hollow fiber membranes. The crosslinked fibers were tested for CO 2/CH 4 separation. The excellent plasticization resistance under high pressure feeds (with highest CO 2 partial pressure of 400psia) suggests that these robust membranes are promising for aggressive natural gas purification. © 2011 Elsevier B.V.

  8. Transparent anti-stain coatings with good thermal and mechanical properties based on polyimide-silica nanohybrids.

    Science.gov (United States)

    Choi, Myeon-Cheon; Sung, Giju; Nagappan, Saravanan; Han, Mi-Jeong; Ha, Chang-Sik

    2012-07-01

    In this work, we synthesized polyimide/silica hybrid materials via sol-gel method using a fluorinated poly(amic acid) silane precursor and a variety of perfluorosilane contents. We studied the influence of a hybrid coating film with the following characteristics; hydrophobicity, oleophobicity, optical transparency, and surface hardness of the coating films. The hybrid coatings with the fluorosilane contents up to 10 wt% are optically transparent and present good thermal stability with a degradation temperature of > 500 degrees C as well as a glass transition of > 300 degrees C. Both water contact angle and oil contact angle increase rapidly with introducing small amount of the fluorosilane in the hybrids and reaches the maximum of 115 degrees and 61 degrees, respectively. The hardness of the hybrid coatings increases up to 5H with an increase of the FTES content in the hybrids. These colorless, transparent, and thermally stable hybrid materials could be suitable for applications as anti-stain coatings.

  9. Synthesis of Cu or Cu2O-polyimide nanocomposites using Cu powders and their optical properties

    Science.gov (United States)

    Choi, Dong Joo; Maeng, Ju Sung; Ahn, Key-one; Jung, Myoung Jin; Song, Seok Ho; Kim, Young-Ho

    2014-09-01

    Nanocomposites consisting of Cu or Cu2O nanoparticles in various polyimide (PI) films were successfully prepared using polyamic acid (PAA) and Cu powders. Cu powders were dissolved into PAA solutions, and the solutions were spin-coated onto the substrates. Cu or Cu2O nanoparticles were formed in PI film by curing in a reducing or inert atmosphere, respectively. The Cu nanoparticles were transformed to Cu2O nanoparticles by post-heat treatment in an oxidizing atmosphere after curing in a reducing atmosphere. Transmission electron microscopy showed that uniform, round Cu2O nanoparticles 6.0 nm in diameter were dispersed in the PI film by post-heat treatment. The addition of Cu2O nanoparticles in the 4,4‧-(hexafluoroisopropylidene)diphthalic anhydride-4,4‧-oxydianiline (6FDA-ODA) PI film enhanced the refractive index of the 6FDA-ODA PI film from 1.60 to 1.72 at 633 nm, and the transparency of the nanocomposite film was about 70-90% in the visible region and remained around 90% beyond 550 nm.

  10. Study on Preparation of High-k Organic-Inorganic Thin Film for Organic-Inorganic Thin Film Transistor Gate Dielectric Application

    Science.gov (United States)

    Lee, Wen-Hsi; Liu, Chao-Te; Lee, Ying-Chieh

    2012-06-01

    A simple solution-based deposition technique combined with spin-coating is a plausible way to prepare ultra-thin organic-inorganic nanocomposite films. In this study, we describe the spin-coating deposition of a colloidal nanoparticle suspension to obtain an ultra-thin organic-inorganic composite film as a gate insulator for organic thin film transistor (O-TFT) application. To obtain a homogenous organic-inorganic composite film, well-dispersed TiO2 nanoparticles in γ-butyrolactone and polyimide are important; therefore, several dispersants were assessed on the basis of the measurement of the rheological behavior of slurries. The thickness of the organic-inorganic composite film is mainly determined by the speed of spin-coating and viscosity of slurries. An approximately 4000-Å-thick nanocomposite film with homogeneous distribution of TiO2 nanoparticles in polyimide and low roughness was obtained after curing at 200 °C, resulting in a low leakage current density of the nano-composite film, when less than 2 vol % TiO2 nanoparticles were well dispersed in polyimide slurry. The dielectric constant of the organic-inorganic nanocomposite increases with increasing TiO2 content in polyimide, being situated in the range between 4 and 5.

  11. Thin film interconnect processes

    Science.gov (United States)

    Malik, Farid

    Interconnects and associated photolithography and etching processes play a dominant role in the feature shrinkage of electronic devices. Most interconnects are fabricated by use of thin film processing techniques. Planarization of dielectrics and novel metal deposition methods are the focus of current investigations. Spin-on glass, polyimides, etch-back, bias-sputtered quartz, and plasma-enhanced conformal films are being used to obtain planarized dielectrics over which metal films can be reliably deposited. Recent trends have been towards chemical vapor depositions of metals and refractory metal silicides. Interconnects of the future will be used in conjunction with planarized dielectric layers. Reliability of devices will depend to a large extent on the quality of the interconnects.

  12. Rubbing-Induced Molecular Reorientation on an Alignment Surface of an Aromatic Polyimide Containing Cyanobiphenyl Side Chains

    Science.gov (United States)

    Cheng, S. Z. D.; Ge, Jason J.; Li, Christopher Y.; Harris, Frank W.; Hong, Seok-Cheol; Zhuang, Xiaowei; Shen, Y. R.

    2002-03-01

    Surface lamellar decoration (SLD), surface enhanced Raman scattering (SERS) and optical second harmonic generation (SHG) experiments have been utilized to study the molecular orientation and conformation changes at a rubbed polyimide alignment layer surface. This aromatic polyimide containing pendent cyanobiphenyl mesogens was synthesized via a polycondensation, and abbreviated as 6FDA-6CBBP. Uniform alignment layers, possessing high pretilt angles ranging from 39^o to 43^o, have been achieved after mechanical rubbing of the polyimide thin film surface at room temperature and subsequent annealing. This is the first time that high pretilt angles have been detected to possess a negative angle [θ(c)] with respect to the rubbing direction (i.e., opposite to the rubbing direction), considerably different from the conventional pretilt angle [θc)] observed along the rubbing direction. Combined polyethylene (PE) SLD and atomic force microscopy experiments reveal that the azimuthal orientation distribution of the long axis of the edge-on PE lamellar crystals is oriented normal to the rubbing direction, indicating that the PE chains are aligned parallel to the rubbing direction. The SERS results show that mechanical rubbing causes not only tilting of the backbone moieties, but also significant conformational rearrangements of the pendent side chains at the surfaces. The molecular mechanism of this unusual alignment is due to the fact that the pendent cyanobiphenyls forms a uniformly tilted conformation on the rubbed surface, and the polar cyano groups point down towards the layer surface deduced from SHG phase measurements. This conformational rearrangement of the side chains results in the formation of fold-like bent structures on the surface, which directly leads to the long axis of cyanobiphenyls having the [θc)] pretilt angle with respect to the rubbing direction.

  13. Uniaxial Stretching of Poly(keto-ether-imide) Films

    Science.gov (United States)

    Hinkley, Jeffrey A.; Dezern, James F.; Feuz, L.; Klinedinst, D.

    1999-01-01

    Fully-cured aromatic polyimides were prepared from various combinations of five dianhydrides and six diamines. When heated progressively under constant load, most of the films elongated rapidly near their glass transition temperatures. In about half of the nineteen materials, the strain was self-limiting - a possible indication of strain-induced crystallinity. The presence of crystallinity was established unambiguously for one material.

  14. Radiation Abating Highly Flexible Multifunctional Polyimide Cryogenic and Thermal Insulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The development of highly flexible thermal insulation materials with multifunctional properties based in polyimide polymers and designed to provide significant...

  15. Photochemical Cyclopolymerization of Polyimides in Ultraviolet Ridgidizing Composites for Use in Inflatable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This innovation uses photochemical cyclopolymerization of polyimides to manufacture ultraviolet rigidizable composites for use in RIS (ridgidizing inflatable)...

  16. Chain Conformation and Local Rigidity of Soluble Polyimides(Ⅱ): Isomerized Polyimides in THF

    Institute of Scientific and Technical Information of China (English)

    LIU Gui-hua; QIU Xue-peng; BO Shu-qin; JI Xiang-ling

    2012-01-01

    Two soluble isomerized polyimides(PIs)synthesized from 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride(6FDA)with either 2,2′-dimethylbenzidine(2,2′-DMB)or 3,3′-DMB were investigated by means of size-exclusion chromatography coupled with multi-angle laser light scattering,a viscometer and a refractive index detector in tetrahydrofuran(THF)with tetrabutylammonium bromide(TBAB)at 35 ℃.The corresponding parameters related to conformations α and v,evaluated from the scaling relationships[η]=KηMa and Rg=KgMv,respectively,were 0.66±0.01 and 0.55±0.02 for poly(6FDA/3,3'-DMB),and 0.67±0.01 and 0.56±0.01 for poly(6FDA/2,2'-DMB),indicating a random coil conformation for both the samples in this mobile system.The persistence length lp and shift factor ML(relative molecular weight per unit contour length)were estimated from the relationship between intrinsic viscosity and molecular weight for the wormlike cylinder model proposed by Bohdanecky.Both lp and ML showed that the two PIs in THF are flexible chains and exhibit some local rigidity to some extent.

  17. Interfacial microstructure and reaction at the spin-coated fluorinated polyimide/Al interface: surface-enhanced X-ray diffraction and TEM studies

    Science.gov (United States)

    Tong, H. Y.; Shi, F. G.; Zhao, B.; Wang, S.-Q.; Brongo, M.; Vasudev, P. K.

    Fluorinated polyimides (FPIs) are being investigated as interlevel dielectrics (ILDs) in future multilevel interconnect technologies because of their low intrinsic dielectric constant. This study investigates the effect of thermal treatment in a pure nitrogen atmosphere on the interfacial microstructure and chemistry at the interface between a FPI thin film and its contacted Al layer in FPI/Al/Ti/SiO2 multilayers by means of X-ray diffraction, transmission electron microscopy, and an ellipsometer. The FPI precursor, a solution of PMDA/6FDA/TFMOB/PPD was spin-coated onto the Al layer and then cured at 400 °C for one hour. It is found that the moisture and oxygen from the FPI layer released during thermal treatment can lead to the oxidation of the interface between the Al and the FPI. The TEM cross-sectional images and the electron diffraction patterns indicate that the oxidized interface is amorphous. The oxidation product is identified to be Al2O3. The oxidation onset temperature is determined to be 415 °C, which is slightly higher than the curing temperature. The oxidation of the FPI/Al interface results in an increase in the electrical resistance of the Al layer, and thus may lead to a reduction in its effective electrical thickness.

  18. Superhydrophobic Polyimide via Ultraviolet Photooxidation: The Evolution of Surface Morphology and Hydrophobicity under Different Ultraviolet Intensities

    Directory of Open Access Journals (Sweden)

    Hongyu Gu

    2015-01-01

    Full Text Available Ultraviolet (UV photooxidation has recently been developed to fabricate superhydrophobic polyimide (PI films in combination with fluoroalkylsilane modification. However, it remains unclear whether the surface morphology and hydrophobicity are sensitive to technical parameters such as UV intensity and radiation environment. Herein, we focus on the effects of UV intensity on PI surface structure and wettability to gain comprehensive understanding and more effective control of this technology. Scanning electron microscopy (SEM and atomic force microscopy (AFM results showed that UV intensity governed the evolutionary pattern of surface morphology: lower UV intensity (5 mW/cm2 facilitated in-plane expansion of dendritic protrusions while stronger UV (10 and 15 mW/cm2 encouraged localized growth of protrusions in a piling-up manner. Surface roughness and hydrophobicity maximized at the intensity of 10 mW/cm2, as a consequence of the slowed horizontal expansion and preferred vertical growth of the protrusions when UV intensity increased. Based on these results, the mechanism that surface micro/nanostructures developed in distinct ways when exposed to different UV intensities was proposed. Though superhydrophobicity (water contact angle larger than 150° can be achieved at UV intensity not less than 10 mW/cm2, higher intensity decreased the effectiveness. Therefore, the UV photooxidation under 10 mW/cm2 for 72 h is recommended to fabricate superhydrophobic PI films.

  19. Novel Soluble Polyimide Containing 4-tert-Butyltoluene Moiety: Synthesis and Characterization

    Institute of Scientific and Technical Information of China (English)

    WANG, Chenyi; LI, Guang; JIANG, Jianming

    2009-01-01

    Based on the synthesis of a rigid aromatic diamine, α,α-bis(4-aminophenyl)-4-(t-butyl)toluene (1), a novel polyimide (PI) 3 was prepared from this diamine monomer and 4,4'-oxydiphthalic dianhydride via a one-step high-temperature polycondensation. FT-IR, ~1H NMR and elemental analysis were used to investigate the chemical structures of 1 and 3. The results confirmed that they agreed with the proposed structures for both 1 and 3 completely. The obtained PI 3 showed excellent solubility in most common solvents such as N-methyl-2-pyrrolidinone,N,N-dimethylacetamide, N,N-dimethylformamide, chloroform, dichloromethane and tetrahydrofuran. The resulting strong and flexible film exhibited high thermal stability with the glass transition temperature at 317 ℃ and the temperature at 10% weight loss beyond 519 ℃ in both air and nitrogen atmospheres. Moreover, the film also showed high optical transparency, low dielectric constant (3.13 at 1 MHz), low water absorption (0.40%) and hydrophobic character.

  20. Pulsed laser interference patterning of polyimide grating for dye-doped polymer laser

    Science.gov (United States)

    Kok, Soon Yie; Tou, Teck Yong; Yap, Seong Ling; Yap, Seong Shan

    2016-07-01

    Direct laser interference patterning of polyimide (PI) films was performed by using a pulsed 355-nm laser. At laser fluence of 0.4 J/cm2, gratings with spatial periods of 3.8 μm to 344 nm were created. The highest aspect ratio of the grating structure (0.8) was obtained for the 344-nm grating. An all-polymer dye laser was then fabricated by spin-coating a layer of disodium fluorescein (DF)-doped polyvinyl alcohol (PVA) film on bare and patterned PI substrate. Green laser emission was obtained when transversely pumped by a 355-nm laser. The lasing threshold reduced by ˜10 times for the sample with 344-nm grating while the laser intensity was ˜18 times higher. The enhancements are ascribed to the 344-nm grating structures, which act as an efficient distributed feedback resonator and distributed Bragg reflector grating for DF-doped PVA emitting at ˜563 nm, on top of being a passive light-trapping structures.

  1. Polyimide and Metals MEMS Multi-User Processes

    KAUST Repository

    Arevalo, Arpys

    2016-11-01

    The development of a polyimide and metals multi-user surface micro-machining process for Micro-electro-mechanical Systems (MEMS) is presented. The process was designed to be as general as possible, and designed to be capable to fabricate different designs on a single silicon wafer. The process was not optimized with the purpose of fabricating any one specific device but can be tweaked to satisfy individual needs depending on the application. The fabrication process uses Polyimide as the structural material and three separated metallization layers that can be interconnected depending on the desired application. The technology allows the development of out-of-plane compliant mechanisms, which can be combined with six variations of different physical principles for actuation and sensing on a single processed silicon wafer. These variations are: electrostatic motion, thermal bimorph actuation, capacitive sensing, magnetic sensing, thermocouple-based sensing and radio frequency transmission and reception.

  2. UV Direct-Writing of Metals on Polyimide

    CERN Document Server

    Ng, Jack Hoyd-Gigg; Mccarthy, Aongus; Suyal, Himanshu; Prior, Kevin; Hand, Duncan P

    2008-01-01

    Conductive micro-patterned copper tracks were fabricated by UV direct-writing of a nanoparticle silver seed layer followed by selective electroless copper deposition. Silver ions were first incorporated into a hydrolyzed polyimide surface layer by wet chemical treatment. A photoreactive polymer coating, methoxy poly(ethylene glycol) (MPEG) was coated on top of the substrate prior to UV irradiation. Electrons released through the interaction between the MPEG molecules and UV photons allowed the reduction of the silver ions across the MPEG/doped polyimide interface. The resultant silver seed layer has a cluster morphology which is suitable for the initiation of electroless plating. Initial results showed that the deposited copper tracks were in good agreement with the track width on the photomask and laser direct-writing can also fabricate smaller line width metal tracks with good accuracy. The facile fabrication presented here can be carried out in air, at atmospheric pressure, and on contoured surfaces.

  3. New Endcaps for Improved Oxidation Resistance in PMR Polyimides

    Science.gov (United States)

    Frimer, Aryeh A.

    2003-01-01

    A polyimide is a polymer composed of alternating units of diamine and dianhydride, linked to each other via an imide bond. PMR polyimides, commonly used in the aerospace industry, are generally capped at each end by an endcap (such as the nadic endcap used in PMR 15) which serves a double function: (1) it limits the number of repeating units and, hence, the average molecular weight of the various polymer chains (oligomers), thereby improving processibility; (2) Upon further treatment (curing), the endcap crosslinks the various oligomer strands into a tough heat-resistant piece. It is this very endcap, so important to processing, that accounts for much of the weight loss in the polymer on aging in air at elevated temperatures. Understanding this degradation provides clues for designing new endcaps to slow down degradation, and prolong the lifetime of the material.

  4. A MOLECULAR APPROACH TO THE SYNTHESIS OF NOVEL POLYIMIDES

    Institute of Scientific and Technical Information of China (English)

    Zhi-yuan Wang

    1999-01-01

    In the past ten years there has been a flurry of activity in the synthesis of new specialty polymers,largely as a result of the increased need for high technology materials. Interest is mainly shown in two distinct categories of polymers: a) polymers which are used in very small quantities to fulfill critical needs as a part of device systems, and b) high-performance engineering polymers which significantly extend their mechanical and thermal properties for structural applications. Polyimides and their unparalleled versatility have captured the attention and imagination of scientists and engineers. This article describes some of the recent work done by the author's group on the rational design at the molecular level and the synthesis of polyimides that have unusual structures and novel properties.

  5. Synthesis and Characterization of Thermosetting Polyimide Oligomers for Microelectronics Packaging

    OpenAIRE

    2000-01-01

    A series of reactive phenylethynyl endcapped imide oligomers has been prepared in either fully cyclized or amic acid precursor form. Soluble oligomers have been synthesized with controlled molecular weights ranging from 2- to 12 Kg/mol. Molecular weight characterization was performed using SEC (size exclusion chromatography) and 13C-NMR, revealing good agreement between the theoretical and experimental (Mn) values. Crosslinked polyimides were obtained by solution or melt processing the oli...

  6. High Temperature VARTM with LaRC Polyimides

    Science.gov (United States)

    Cano, Roberto J.; Grimsley, Brian W.; Jensen, Brian J.; Kellen, Charles B.

    2004-01-01

    Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems for advanced aerospace applications that can be processed without the use of an autoclave. Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Vacuum assisted resin transfer molding (VARTM) has shown potential to reduce the manufacturing cost of composite structures. In VARTM, the fibrous preform is infiltrated on a rigid tool surface contained beneath a flexible vacuum bag. Both resin injection and fiber compaction are achieved under pressures of 101.3 KPa or less. Recent studies have demonstrated the feasibility of the VARTM process for fabrication of void free structures utilizing epoxy resin systems with fiber volume fractions approaching 60%. In this work, the VARTM process has been extended to the fabrication of composite panels from polyimide systems developed at the Langley Research Center. This work has focused on processing LARC(trademark) PETI-8 (Langley Research Center Phenylethynyl Terminated Imide- 8), an aromatic polyimide based on 3,3',4,4' -biphenyltetracarboxylic dianhydride, a 50:50 molar ratio of 3,4'-oxydianiline and 1,3-bis(3-aminophenoxy)benzene, with 4-phenylethynylphthalic anhydride as the endcapping agent. Various molecular weight versions were investigated to determine their feasibility of being processed by VARTM at elevated temperatures. An injection temperature of approximately 280 C was required to achieve the necessary viscosity (VARTM pressures. Laminate quality and initial mechanical properties are presented for LARC(trademark) PETI-8 and 6k IM7 uniweave fabric.

  7. UV Direct-Writing of Metals on Polyimide

    OpenAIRE

    Ng, Jack Hoyd-Gigg; Desmulliez, Marc; McCarthy, Aongus; Suyal, Himanshu; Prior, Kevin; Hand, Duncan P.

    2008-01-01

    Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838); International audience; Conductive micro-patterned copper tracks were fabricated by UV direct-writing of a nanoparticle silver seed layer followed by selective electroless copper deposition. Silver ions were first incorporated into a hydrolyzed polyimide surface layer by wet chemical treatment. A photoreactive polymer coating, methoxy poly(ethylene glycol) (MPEG) was coated on top of the substrate p...

  8. Flexible Quasi-Two-Dimensional CoFe2O4 Epitaxial Thin Films for Continuous Strain Tuning of Magnetic Properties.

    Science.gov (United States)

    Zhang, Yong; Shen, Lvkang; Liu, Ming; Li, Xin; Lu, Xiaoli; Lu, Lu; Ma, Chunrui; You, Caiyin; Chen, Aiping; Huang, Chuanwei; Chen, Lang; Alexe, Marin; Jia, Chun-Lin

    2017-08-22

    Epitaxial thin films of CoFe2O4 (CFO) have successfully been transferred from a SrTiO3 substrate onto a flexible polyimide substrate. By bending the flexible polyimide, different levels of uniaxial strain are continuously introduced into the CFO epitaxial thin films. Unlike traditional epitaxial strain induced by substrates, the strain from bending will not suffer from critical thickness limitation, crystalline quality variation, and substrate clamping, and more importantly, it provides a more intrinsic and reliable way to study strain-controlled behaviors in functional oxide systems. It is found that both the saturation magnetization and coercivity of the transferred films can be changed over the bending status and show a high accord with the movement of the curvature bending radius of the polyimide substrate. This reveals that the mechanical strain plays a critical role in tuning the magnetic properties of CFO thin films parallel and perpendicular to the film plane direction.

  9. Action of colloidal silica films on different nano-composites

    Science.gov (United States)

    Abdalla, S.; Al-Marzouki, F.; Obaid, A.; Gamal, S.

    Nano-composite films have been the subject of extensive work to develop the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nano-particles size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that form an insulating film between conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of 4 high pure amorphous polymer films: polymethylmethacrylate (PMMA), polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher break down performance is a character of polyimide PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  10. EFFECT OF HOT STRETCHING ON THE STRUCTURE OF POLYIMIDE FROM 1,4--BIS (3', 4'--DICARBOXYPHENOXY) BENZENE AND 4,4 -'OXYDIANILINE

    Institute of Scientific and Technical Information of China (English)

    SUN Zhenhua; DING Mengxian; FENG Zhiliu

    1992-01-01

    The structure of polyimide from 1,4-bis (3', 4'-dicarboxyphenoxy ) benzene and 4,4'-oxydianiline film specimens before and after hot stretching has been investigated by WAXD, DSC and FTIR. As evidenced by both the WAXD and DSC results, it could be believed that strain induced crystallization did take place after hot stretching. Meanwhile, shifting position and splitting of some band peaks existed on the FTIR spectrograms were explained in terms of the close packing of chains and the changes of inter-molecular charge-transfer interaction between imide groups and aromatic groups upon crystallization.

  11. Fluence and fluence rate effects on electrical conductivity and shrinkage in polyimide bombarded by an ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Trigaud, T. [LEPOFI, Faculte des Sci., Limoges (France); Moliton, J.P. [LEPOFI, Faculte des Sci., Limoges (France); Jussiaux, C. [LEPOFI, Faculte des Sci., Limoges (France); Maziere, B. [LEPOFI, Faculte des Sci., Limoges (France)

    1996-02-01

    When the ion fluence is increasing, a diminishing of the thickness and a rise in electrical conductivity can be simultaneously observed with polyimide films. However, in the 100 keV energy range, a saturation limit appears in both processes. Two experimental processes are presented to increase the conductivity limit ({approx_equal}10{sup -1} S cm{sup -1} with N{sup +} ions), while the shrinkage effect is maintained or even reduced. (1) Multiple irradiations of N{sup +} ions implemented from high to low energies induce tenfold increase in conductivity, and stop the thickness decrease beyond a fluence threshold. (2) Liquid-metal ion sources (LMIS) with Ga{sup +} ions (keV) perform high conductivities (above 300 S cm{sup -1}) without notable shrinkage. (orig.).

  12. Effect of substrate bias on the structural and electrical properties of sputtered Mo thin films on flexible substrates.

    Science.gov (United States)

    Xu, Jiaxiong

    2016-07-04

    The metal molybdenum (Mo) thin films deposited on flexible substrates can act as the contact electrode of flexible Cu(In,Ga)Se2 or Cu2ZnSn(S,Se)4 solar cells. In this work, in order to enhance the structural and electrical characteristics of flexible Mo thin films, a negative substrate bias was applied during the direct current sputtering of Mo thin films. The flexible substrates used for growing the Mo films were stainless steel foils and polyimides. The characteristics of Mo thin films were studied by x-ray diffraction and sheet resistance measurements. The measured results reveal that an optimal value of negative substrate bias can be found for improving the electrical and structural characteristics of Mo thin films on flexible substrates. The minimum sheet resistances of Mo thin films are 2.50 Ω/sq and 2.73 Ω/sq for the stainless steel foil and polyimide substrates, respectively.

  13. Characterization of Polyimide Foams for Ultra-Lightweight Space Structures

    Science.gov (United States)

    Meador, Michael (Technical Monitor); Hillman, Keithan; Veazie, David R.

    2003-01-01

    Ultra-lightweight materials have played a significant role in nearly every area of human activity ranging from magnetic tapes and artificial organs to atmospheric balloons and space inflatables. The application range of ultra-lightweight materials in past decades has expanded dramatically due to their unsurpassed efficiency in terms of low weight and high compliance properties. A new generation of ultra-lightweight materials involving advanced polymeric materials, such as TEEK (TM) polyimide foams, is beginning to emerge to produce novel performance from ultra-lightweight systems for space applications. As a result, they require that special conditions be fulfilled to ensure adequate structural performance, shape retention, and thermal stability. It is therefore important and essential to develop methodologies for predicting the complex properties of ultra-lightweight foams. To support NASA programs such as the Reusable Launch Vehicle (RLV), Clark Atlanta University, along with SORDAL, Inc., has initiated projects for commercial process development of polyimide foams for the proposed cryogenic tank integrated structure (see figure 1). Fabrication and characterization of high temperature, advanced aerospace-grade polyimide foams and filled foam sandwich composites for specified lifetimes in NASA space applications, as well as quantifying the lifetime of components, are immensely attractive goals. In order to improve the development, durability, safety, and life cycle performance of ultra-lightweight polymeric foams, test methods for the properties are constant concerns in terms of timeliness, reliability, and cost. A major challenge is to identify the mechanisms of failures (i.e., core failure, interfacial debonding, and crack development) that are reflected in the measured properties. The long-term goal of the this research is to develop the tools and capabilities necessary to successfully engineer ultra-lightweight polymeric foams. The desire is to reduce density

  14. Synthesis and Characterization of Photosensitive Polyimides for Optical Applications

    Science.gov (United States)

    Kim, Kye-Hyun

    1995-11-01

    The objective of this research was to prepare photosensitive polyimides for optical applications. The work was begun with the synthesis of a series of poly(amic esters) containing cinnamyl groups. However, these systems required high imidization temperatures where they darkened considerably. Two new photosensitive end-capping agents, i.e., 6-(4-aminophenoxy)hexyl methacrylate, and di(2-(methacryloyloxy)ethyl) 5-aminoisophthalate, for polyimides were also prepared. These agents were used along with 2,2^' -bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2^'-bis(trifluoromethyl) -4,4^' -diaminobiphenyl (PFMB) to prepare a series of methacrylate end-capped imide oligomers. However, the oligomers required long exposures to UV-radiation to affect cure. To improve their photosensitivity, multifunctional additives and photoinitiators were used. A difunctional end-capped oligomer that contained trimethylolpropane triacrylate (TMPTA) and trimethylbenzoyldiphenyl phosphine oxide (TMDPO) was highly photosensitive and displayed good photo-patterning properties. The third approach involved the synthesis of a diamine monomer in which methacrylate moieties were attached to the 2- and 2^ '-positions of biphenyl structures. The monomer, i.e., 2,2^'-dimethacryloyloxy -4,4^'-diaminobiphenyl (DMB), was polymerized with commercially available dianhydrides such as 6FDA and 4,4^' -oxydiphthalic anhydride (ODPA). The polyimides obtained were optically transparent and soluble in common organic solvents such as acetone and chloroform. The polymers were highly photosensitive and displayed good photo-patterning properties. The polymers, which afforded high-resolution patterns, did not develop color or shrink during UV-exposure and thermal curing.

  15. An Investigation of the Structure-Property Relationships for High Performance Thermoplastic Matrix, Carbon Fiber Composites with a Tailored Polyimide Interphase

    OpenAIRE

    Gardner, Slade Havelock II

    1998-01-01

    The aqueous suspension prepregging technique was used to fabricate PEEK and PPS matrix composites with polyimide interphases of tailored properties. The structure-property relationships of Ultem-type polyimide and BisP-BTDA polyimide which were made from various water soluble polyamic acid salts were studied. The molecular weight of the polyimides was shown to be dependant upon the selection of the base used for making the polyamic acid salt. The development of an Ultem-type polyimide with...

  16. New aromatic polyamides and polyimides having an adamantine bulky group

    OpenAIRE

    2015-01-01

    Producción Científica This paper reports the synthesis and characterization of a new rigid diamine monomer, having a spiro carbon moiety and an adamantane bulky group in its structure; namely spiro-(adamantane-2,9′(2',7'-diamino)-fluorene) (SADAF). After its synthesis, using a straightforward methodology, a novel family of aromatic polyimides (PIs) and polyamides (PAs) has been attained by reaction of SADAF with three aromatic dianhydrides and two diacid chlorides, respectively. Two of the...

  17. Separation of hydrogen isotopes from nitrogen with polyimide membrane

    Energy Technology Data Exchange (ETDEWEB)

    Labrune, D.; Limacher, B.; Guidon, H. [Commissariat a l`Energie Atomique, Bruyeres-le-Chatel (France); Moll, G. [Societe Generale des Techniques Nouvelles, Saint Quentin Yvelines (France)

    1995-10-01

    Gas separation tests were performed with nitrogen containing small concentrations of deuterium or tritium on a small-scale polyimide membrane module purchased from Ube Industries, similar to that developed at the Japan Atomic Energy Research Institute (JAERI). Experimental results showed that this separation process could be potentially applied to tritium removal systems used in tritium handling facilities. It would permit reducing significantly the gas volume to be treated by the conventional oxidation-adsorption process, and, therefore, the number or size of associated equipment. Hazards from handling highly toxic tritiated water vapor due to conversion of elemental tritium would hence be lowered. 3 refs., 10 figs., 1 tab.

  18. Processable Polyimides Containing APB and Reactive End Caps

    Science.gov (United States)

    Jensen, Brian J.

    2003-01-01

    Imide copolymers that contain 1,3- bis(3-aminophenoxy)benzene (APB) and other diamines and dianhydrides and that are terminated with appropriate amounts of reactive end caps have been invented. The reactive end caps investigated thus far include 4-phenylethynyl phthalic anhydride (PEPA), 3- aminophenoxy-4-phenylethynylbenzop henone (3-APEB), maleic anhydride (MA), and 5-norbornene-2,3-dicarboxylic anhydride [also known as nadic anhydride (NA)]. The advantage of these copolyimides terminated with reactive groups, relative to other polyimides terminated with reactive groups, is a combination of (1) higher values of desired mechanical-property parameters and (2) greater ease of processing into useful parts.

  19. Addition-type polyimides from solutions of monomeric reactants

    Science.gov (United States)

    Delvigs, P.; Serafini, T. T.; Lightsey, G. R.

    1972-01-01

    The monomeric reactants approach was used to fabricate addition-type polyimide/graphite fiber composites with improved mechanical properties and thermal stability characteristics over those of composites derived from addition-type amide acid prepolymers. A screening study of 24 different monomer combinations was performed. The results of a more extensive investigation of a selected number of monomer combinations showed that the combination providing the best thermomechanical properties was 5-norbornene-2,3-dicarboxylic acid monomethyl ester/4,4'-methylenedianiline/3,3'4,4'-benzophenone tetracarboxylic acid dimethyl ester at a molar ratio of 2/3.09/2.09.

  20. The effects of high electronic energy loss on the chemical modification of polyimide

    CERN Document Server

    SunYouMei; Jin Yun Fan; Liu Chang Long; LiuJie; Wang Zhi Guang; Zhang Qi; Zhu Zhi Yong

    2002-01-01

    In order to observe the role of electronic energy loss (dE/dX) sub e on chemical modification of polyimide (PI), the multi-layer stacks (corresponding to different dE/dX) were irradiated by different swift heavy ions (1.37 GeV Ar sup 4 sup 0 , 1.98 GeV Kr sup 8 sup 4 , 1.755 GeV Xe sup 1 sup 3 sup 6 and 2.636 GeV U sup 2 sup 3 sup 8) under vacuum and room temperature. The chemical changes of modified PI films were studied by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/Vis) absorption spectroscopy. The degradation of PI was investigated in the fluence range from 1x10 sup 1 sup 0 to 5.5x10 sup 1 sup 2 ions/cm sup 2 and different electronic energy loss from 0.77 to 11.5 keV/nm. The FTIR results show the absorbance of the typical function group decrease exponentially as a function of fluence. The alkyne end group was found after irradiation and its formation radii were 5.6 and 5.9 nm corresponding to 8.8 and 11.5 keV/nm Xe irradiation respectively. UV/Vis analysis indicates the radiation induced...

  1. Huge nanodielectric effects in polyimide/boron nitride nanocomposites revealed by the nanofiller size

    Science.gov (United States)

    Diaham, S.; Saysouk, F.; Locatelli, M.-L.; Lebey, T.

    2015-09-01

    The dielectric properties of polyimide/boron nitride (PI/BN) nanocomposite films are investigated as a function of the BN nanofiller size from 20 to 350 °C and at low filler content (1-2 vol.%). The role of the BN nanofiller size on the large reduction of the electrode polarization relaxation phenomenon due to ionic movements is reported. For the two smallest BN nanoparticles (95 nm and 35 nm), the permittivity, dielectric losses and dc conductivity are strongly attenuated above 200 °C by a factor of 10 to 1000 compared to neat PI. Thus, the dc conductivity at 350 °C is reduced from 4   ×   10-8 Ω-1 cm-1 for neat PI to 3   ×   10-11 Ω-1 cm-1 for PI/BN (35 nm). Moreover, a further decrease is obtained by functionalizing the nanofiller surface with a silane coupling agent which improves the grafting of PI chains on those latter nanoparticles. These results highlight the trapping efficiency in the interphase region introduced by the small BN nanofillers (<100 nm) and provides evidence as to the huge nanodielectric effects on the charge carrier transport controlled by the nanoparticle diameter. This finding should be of great importance for advanced high temperature electrical insulation in the future.

  2. Cross-Linkable Polyimide Membranes for Improved Plasticization Resistance and Permselectivity in Sour Gas Separations

    KAUST Repository

    Kraftschik, Brian

    2013-09-10

    A series of cross-linkable membrane materials based on the 6FDA-DAM:DABA (3:2) polyimide backbone were synthesized for improved sour gas separation performance, in terms of both membrane stability and permselectivity. Short-chain poly(ethylene glycol) (PEG) molecules were used as cross-linking agents in an esterification-based cross-linking reaction. Pure and mixed gas permeation and pure gas sorption experiments were performed on dense films of these materials. Compared to unmodified 6FDA-DAM:DABA (3:2), higher sour gas permselectivity and membrane stability were achieved under aggressive feed conditions. H2S-induced plasticization was not evident until pure H2S feed pressures greater than approximately 6-8 bar. Pure CO 2-induced plasticization only occurred at feed pressures greater than about 25 bar. Under mixed gas feed conditions with 20% H2S, 20% CO2, and 60% CH4 at 35 C, attractive selectivities above 22 and 27 for H2S/CH4 and CO2/CH4, respectively, were observed for a feed pressure of 62 bar with both triethylene glycol and tetraethylene glycol cross-linking agents. © 2013 American Chemical Society.

  3. Fabrication and characterization of flexible Ag/ZnO Schottky diodes on polyimide substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, XinAn; Zhai, JunXia; Yu, XianKun; Ding, LingHong; Zhang, WeiFeng, E-mail: wfzhang@henu.edu.cn

    2013-12-02

    In this paper, we report on the fabrication of flexible Ag/ZnO Schottky diodes on polyimide substrates by pulsed laser deposition. The structural and optical properties of the ZnO films were investigated by X-ray diffractometry and spectrophotometry. The current–voltage (I–V) characteristics of flexible Schottky diodes with and without bending were measured at room temperature. The results show that the devices have good rectifying behaviors with an ideality factor of 2.8 and a Schottky barrier height of 0.54 eV according to the I–V characteristics. It was seen that the forward bias current–voltage characteristics at sufficiently large voltages have shown the effect of series resistance. The values of the ideality factor, series resistance and barrier height obtained from Cheung and Norde methods were compared, and it was seen that there was an agreement with each other. The results show that the electrical properties of flexible diodes change little when measured with or without bending condition, indicating that the devices have potential applications in flexible electronics. - Highlights: • Flexible Ag/ZnO Schottky diodes were fabricated. • The electrical parameters of the diodes were obtained and analyzed. • The electrical properties of the diodes with bending were also discussed.

  4. Thermosetting Poly(imide silsesquioxane)s Featuring Reduced Moisture Affinity and Improved Processability (Post Print)

    Science.gov (United States)

    2013-09-11

    depending on architecture.21,22 Recently, Kakimoto et al. reported a hybrid organic−inorganic approach to modifying Kapton-like thermoplastic involving...McGrath, J. E. Polymer 1989, 30 (6), 986−95. (23) Wu, S.; Hayakawa, T.; Kikuchi, R.; Grunzinger, S. J.; Kakimoto , M.-A.; Oikawa, H. Macromolecules

  5. High temperature polymer dielectric film-wire insulation

    Science.gov (United States)

    Nairus, John G.

    1994-01-01

    The highlights of the program are outlined including two major accomplishments. TRW identified and demonstrated the potential of two aromatic/heterocyclic polymers to have an outstanding and superior combination of electrical, thermal, and chemical resistance properties versus state-of-the-art Kapton for spacecraft and/or aircraft dielectric insulation applications. (Supporting data is provided in tables.) Feasibility was demonstrated for supporting/enabling technologies such as ceramic coatings, continuous film casting, and conductor wire wrapping, which are designed to accelerate qualification and deployment of the new wire insulation materials for USAF systems applications during the mid- to late-1990's.

  6. Sulfonated polyimides containing triphenylphosphine oxide for proton exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Arun Kumar; Bera, Debaditya; Banerjee, Susanta, E-mail: susanta@matsc.iitkgp.ernet.in

    2016-09-15

    A series of sulfonated co-polyimides (co-SPI) were prepared by one pot polycondensation reaction of a combination of diamines namely; 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) and prepared non-sulfonated diamine (DATPPO) containing triphenylphosphine oxide with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). All these soluble co-SPI gave flexible membranes with high thermal stability and showed good mechanical property. Transmission electron microscopy (TEM) analysis revealed the microphase separated morphology with well-dispersed hydrophilic (cluster size in the range of 5–55 nm) domains. The co-SPI membranes showed high oxidative and hydrolytic stability with higher proton conductivity. All these co-SPI membranes exhibited low water uptake and swelling ratio. The co-SPI membrane TPPO-60 (60% degree of sulfonation) with IEC{sub W} = 1.84 mequiv g{sup −1} showed high proton conductivity (99 mS cm{sup −1} at 80 °C and 107 mS cm{sup −1} at 90 °C) in water with high oxidative (20 h) and hydrolytic stability (only 5% degradation in 24 h). - Highlights: • Triphenylphosphine oxide containing sulfonated polyimides (SPIs) was synthesized. • The SPIs showed good oxidative and hydrolytic stability and high proton conductivity. • TEM analysis revealed well separated morphology of the SPIs.

  7. SYNTHESIS AND CHARACTERIZATION OF POLYIMIDE-ZEOLITE MIXED MATRIX MEMBRANE

    Directory of Open Access Journals (Sweden)

    Budiyono Budiyono

    2012-02-01

    Full Text Available Biogas has become an attractive alternative energy source due to the limitation of energy from fossil. In this study, a new type of mixed matrix membrane (MMM consisting of polyimide-zeolite was synthesized and characterized for biogas purification. The MMM consists of medium concentration of polymer (20% wt polyimide, 80% N-Methyl-2-pyrrolidone (NMP and 25% zeolite 4A in total solid were prepared by a dry/wet phase inversion technique.  The fabricated MMM was characterized using SEM, DSC, TGA and gas permeation. Post treatment coating procedure was also conducted. The research showed that surface coating by 3% silicone rubber toward MMM PI 20% gave the significant effect to improve membrane selectivity. The ideal selectivity for CO2/CH4 separation increased from 0.99 for before coating to 7.9 after coating for PI-Zeolite MMM, respectively. The results suggest that PI-Zeolite MMM with good post treatment procedure will increase the membrane selectivity and permeability with more saver polymer requirement as well as energy saving due to low energy for mixing.

  8. Processing of continuous fiber composites using thermoplastic polyimide matrix resins

    Energy Technology Data Exchange (ETDEWEB)

    Kranjc, M.D.

    1993-01-01

    Composites have been produced which contain a solvent resistant polyimide matrix with favorable physical properties. The polyimide matrix resin has been designated as P12. The prepegs used to produce the composite contain a low molecular weight resin which is the polyamic acid precursor to P12. Polymerization and imidization of the precursor resin occurs in-situ during processing. Similar commercial systems are often processed in an autoclave and pressure is used at high temperatures to obtain consolidation between prepreg laminates. Pressure is generally applied after polymerization and imidization are complete and at temperatures above the melting point of the polymer. In this research a significant decrease in composite void content was obtained by applying pressure earlier in the cure. Obtaining composites with low void content with these types of systems can be difficult. This is due in part to the generation of low molecular weight reaction by products, water and methanol. High void content results in a decrease in the physical properties of the composite structure. This is especially true for fracture properties. An empirical equation was used to describe the rate of resin removal from the composite to the bleeder cloth during processing. This equation is based on Springer-Loos resin flow model. The conditions in which this model does not apply were also determined. Determining resin removal rates is helpful in producing composites with consistent fiber/resin ratios. In addition, conditions which favor void growth can be prevented.

  9. Polyimide/Glass Composite High-Temperature Insulation

    Science.gov (United States)

    Pater, Ruth H.; Vasquez, Peter; Chatlin, Richard L.; Smith, Donald L.; Skalski, Thomas J.; Johnson, Gary S.; Chu, Sang-Hyon

    2009-01-01

    Lightweight composites of RP46 polyimide and glass fibers have been found to be useful as extraordinarily fire-resistant electrical-insulation materials. RP46 is a polyimide of the polymerization of monomeric reactants (PMR) type, developed by NASA Langley Research Center. RP46 has properties that make it attractive for use in electrical insulation at high temperatures. These properties include high-temperature resistance, low relative permittivity, low dissipation factor, outstanding mechanical properties, and excellent resistance to moisture and chemicals. Moreover, RP46 contains no halogen or other toxic materials and when burned it does not produce toxic fume or gaseous materials. The U. S. Navy has been seeking lightweight, high-temperature-resistant electrical-insulation materials in a program directed toward reducing fire hazards and weights in ship electrical systems. To satisfy the requirements of this program, an electrical-insulation material must withstand a 3-hour gas-flame test at 1,600 F (about 871 C). Prior to the development reported here, RP46 was rated for use at temperatures from -150 to +700 F (about -101 to 371 C), and no polymeric product - not even RP46 - was expected to withstand the Navy 3-hour gas-flame test.

  10. Adhesion characteristics of silver tracks screen-printed on polyimide with an environmental reliability test.

    Science.gov (United States)

    Kim, Kwang-Seok; Myung, Woo-Ram; Jung, Seung-Boo

    2012-07-01

    Printable and flexible electronics are increasingly being used in numerous applications that are miniaturized, multi-functional and lightweight. Simultaneously, reliability issues of the printed and flexible electronic devices are getting more attention. The adhesion of screen-printed silver (Ag) tracks on a polyimide (PI) film was investigated after two kinds of the environmental reliability test: a constant-temperature storage test, and a steady-state temperature and humidity storage test. Atmospheric-pressure plasma (APP) was adopted on the PI film surface to improve the poor adhesion derived from the inherent hydrophobicity. The Ag tracks constructed via screen printing were sintered at 250 degrees C for 30 min in air using a box-type muffle furnace. Some samples were exposed under 85 degrees C and 85% relative humidity (RH) for various durations (24, 72, 168 and 500 h), and others were aged at 85 degrees C with same durations to compare the influence of moisture on the adhesion. The adhesion of the screen-printed Ag tracks was evaluated by a roll-type 90 degrees peel test. The peel strength of the screen-printed Ag tracks decreased by 76.74% and 69.88% after 500 h run of the 85 degrees C/85% RH test, and the aging test, respectively. The weakest adhesion was 4.98 gf/mm after the 500 h run of the 85 degrees C/85% RH test. To demonstrate these experimental results, the microstructural evolution and chemical bonding states of the interfacial surfaces were characterized using a field emission scanning electron microscope (FE-SEM), and X-ray photoelectron spectroscope (XPS), respectively.

  11. Soluble Polyimides Bearing Long-Chain Alkyl Groups on Their Side Chain via Polymer Reaction

    OpenAIRE

    2012-01-01

    Novel soluble polyimides having long-chain alkyl groups on their side chain were synthesized via polymer reaction with the polyimides having phenolic OH groups and 3,4,5-tris(dodecyloxy)benzoic acid (12GA) using N,N′-dicyclohexylcarbodiimide (DCC) as a dehydration reagent. The polyimides having phenolic OH groups were synthesized from the tetracarboxylic dianhydrides such as 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (cyclohexene-DA), 4,4′-hexafluoroisoprop...

  12. In situ polymerization and performance of alicyclic polyimide/graphene oxide nanocomposites derived from 6FAPB and CBDA

    Science.gov (United States)

    Lu, Yunhua; Hao, Jican; Xiao, Guoyong; Zhao, Hongbin; Hu, Zhizhi; Wang, Tonghua

    2017-02-01

    A series of alicyclic polyimide/graphene oxide(PI/GO) nanocomposites were successfully prepared by in situ polymerization of 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene(6FAPB) and 1,2,3,4-cyclobutanetetracarboxylic dianhydride(CBDA) as well as GO, followed by thermal imidization. The effect of GO on the thermal stability, optical properties, mechanical properties, water absorption and water surface contact angle of the PI-based nanocomposites was investigated. The optical properties of the pure alicyclic PI and corresponding PI-based nanocomposite films showed that the addition of GO reduced the transparency of PI films in the range of 200-800 nm obviously. With the increase of GO loading, the mechanical and thermal properties of alicyclic PI-based nanocomposites were enhanced. For the PI-1.0%GO nanocomposite films, the tensile strength was increased from 96 MPa (pure PI) to 109 MPa, and the Young's modulus was improved from 2.41 GPa (pure PI) to 3.83 GPa. The 10 wt% decomposition temperature for PI-1.0%GO nanocomposite films was increased from 464 (pure PI) to 481 °C, while the glass transition temperature (Tg) of PI/GO was slightly increased. In addition, the water surface contact angle of PI/GO enhanced from 71° to 82.5°, and the water uptake of PI/GO decreased from 2.58% to 1.48% with increasing the GO loadings. The uniform dispersion of GO in PI matrix was proved, and the pure PI and PI/GO nanocomposite films were amorphous.

  13. Alumina/Polyimide Composite Porous Nanosolid:Dielectric Characteristics and Compressive Strength

    Institute of Scientific and Technical Information of China (English)

    LUAN Chun-hong; GENG Yu-jing; YU Qin-qin; CAO Li-li; LIAN Gang; CUI De-liang

    2012-01-01

    Al2O3 porous nanosolid was prepared via solvothermal hot-press(SHP) method.The dielectric constant of Al2O3 porous nanosolid is as low as 2.34,while its compressive strength is very poor.In order to improve the compressive strength and maitain low dielectric constant,polyimidc was introduced to prepare Al2O3/polyimide composite porous nanosolid.Compared to Al2O3 porous nanosolid,Al2O3/polyimide composite porous nanosolid possesses much higher compressive strength,which reaches its saturation value when the mass loading of polyimide is 7.75%.In addition,the in situ Fourier transformation infrared(FTIR) monitoring result reveals that Al2O3/polyimide composite porous nanosolid is stable up to 400 ℃.

  14. Functionally Graded Polyimide Nanocomposite Foams for Ablative and Inflatable/Flexible/Deplorable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposed research is to develop functionally graded polyimide foams as light-weight, high performance thermal protection systems (TPS) for...

  15. Sub- T g Cross-Linking of a Polyimide Membrane for Enhanced CO 2 Plasticization Resistance for Natural Gas Separation

    KAUST Repository

    Qiu, Wulin

    2011-08-09

    Decarboxylation-induced thermal cross-linking occurs at elevated temperatures (∼15 °C above glass transition temperature) for 6FDA-DAM:DABA polyimides, which can stabilize membranes against swelling and plasticization in aggressive feed streams. Despite this advantage, such a high temperature might result in collapse of substructure and transition layers in the asymmetric structure of a hollow fibers based on such a material. In this work, the thermal cross-linking of the 6FDA-DAM:DABA at temperatures much below the glass transition temperature (∼387 °C by DSC) was demonstrated. This sub-Tg cross-linking capability enables extension to asymmetric structures useful for large scale membranes. The resulting polymer membranes were characterized by swelling in known solvents for the un-cross-linked materials, TGA analysis, and permeation tests of aggressive gas feed stream at higher pressure. The annealing temperature and time clearly influence the degree of cross-linking of the membranes, and results in a slight difference in selectivity for membranes under various cross-linking conditions. Results indicate that the sub-Tg thermal cross-linking of 6FDA-DAM:DABA dense film membrane can be carried out completely even at a temperature as low as 330 °C. Permeabilities were tested for the polyimide membranes using both pure gases (He, O2, N2, CH4, CO2) and mixed gases (CO2/CH4). The selectivity of the cross-linked membrane can be maintained even under very aggressive CO2 operating conditions that are not possible without cross-linking. Moreover, the plasticization resistance was demonstrated up to 700 psia for pure CO 2 gas or 1000 psia for 50% CO2 mixed gas feeds. © 2011 American Chemical Society.

  16. Study of copper diffusion into polyimides by optical second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.Y.; Shen, Y.R. (California Univ., Berkeley, CA (USA). Dept. of Physics Lawrence Berkeley Lab., CA (USA)); Soane, D.S.; Pauschinger, D. (California Univ., Berkeley, CA (USA). Dept. of Chemical Engineering Lawrence Berkeley Lab., CA (USA))

    1990-08-01

    Formation of Cu clusters deposited on polyimide and their diffusion into polyimide have been studied in-situ by the surface-sensitive second harmonic generation technique. The diffusion coefficients of Cu clusters were measured and compared with those for atomic Cu. The effectiveness of a titanium (Ti) intermediate layer in preventing Cu diffusion into Pl was also investigated. It was found that an atomic layer of Ti was already sufficient for arresting the diffusion process. 15 refs., 5 figs.

  17. Synthesis and characterization of polyimides containing 4,4'-hexafluoroisopropylidene-bisphthalic

    OpenAIRE

    1999-01-01

    This paper presents the synthesis and characterization of polyimides, which contain a 4,4'-hexafluoroisopropylidene-bisphthalic anhydride (6FDA) unit in the backbone. These polyimides are a result of the use of the traditional method of "one step". The reactions occur between equimolar of a dianhydride and an aromatic diamine in presence of the solvent dimethylacetamide (DMAc), then cyclo-dehydrided by adding the acetic anhydride and pyridine. In this work, the 6FDA was used as the dianhydrid...

  18. Molecular Engineering of Azobenzene-Functionalized Polyimides to Enhance Both Photomechanical Work and Motion (POSTPRINT)

    Science.gov (United States)

    2014-09-01

    Information. The materials were characterized by wide-angle X-ray scattering ( WAXS ), dynamic mechanical analysis (DMA), and UV−vis spec- troscopy to... Synthetic Procedure for Linear Polyimides Chemistry of Materials Article dx.doi.org/10.1021/cm5018757 | Chem. Mater. 2014, 26, 5223−52305224 2...Scheme 2. Synthetic Procedure for Cross-Linked Polyimides Chemistry of Materials Article dx.doi.org/10.1021/cm5018757 | Chem. Mater. 2014, 26, 5223

  19. Study on process and characterization of high-temperature resistance polyimide composite

    Science.gov (United States)

    Pan, Ling-Ying; Zhao, Wei-Dong; Liu, Han-Yang; Cui, Chao; Guo, Hong-Jun

    2016-05-01

    A novel polyimide composite with upper-use temperature of 420°C was prepared by autoclave process. The thermogravimetic analysis and rheological properties of uncured polyimide resin powders were analyzed. The influences of process parameters and post-treatment process on the properties of composites were also investigated. The morphologies of polyimide composites after shear fracture were observed by scanning electron microscope (SEM). The high-temperature resistance of composite was characterized by dynamic mechanical thermal analyzer (DMTA). Results showed that the imidization reaction mainly occurred in the temperature range of 100°C~220°C, and the largest weight loss rate appearing at 145°C indicated a drastic imidization reaction occurred. The melt viscosity of polyimide resin decreased with increasing the temperature between 220°C ˜305°C, and then increased with the increase of temperature due to the molecular crosslinking reactions. The fiber volume contents and void contents could be effectively controlled by applying the pressure step by step. The fiber volume content was sensitive to the initial pressure (Pi) during the imidization. The second-stage pressure (P2) and the temperature for applying the P2 (T2) during the imidization had a great effect on the void content of composite. Good mechanical properties and interfacial adhesion of polyimide composite could obtain by optimized process. The post-treatment process can obviously increase the high-temperature resistance of polyimide composite. The polyimide composite treated at 420°C exhibited good retention of mechanical properties at 420°C and had a glass transition temperature (Tg) of 456°C. The retentions of flexible strength, flexible modulus and short beam shear strength of polyimide composite at 420°C were 65%, 84% and 62% respectively.

  20. A review of dynamic mechanical characterization of high temperature PMR polyimides and composites

    Science.gov (United States)

    Pater, Ruth H.

    1988-01-01

    This paper reviews the applications of dynamic mechanical characterization for high-temperature PMR polyimides and their graphite-fiber-reinforced composites. This characterization technique provides insights into the processability, performance, and structure property relationships of the polyimides and composites. The dynamic mechanical properties of various molding powders, commercially obtained prepregs, neat resins, and as-fabricated as well as aged composites are presented. Some applied aspects of the dynamic mechanical data are discussed.

  1. Electro-optical and physic-mechanical properties of colored alicyclic polyimide

    Science.gov (United States)

    Kravtsova, V.; Umerzakova, M.; Korobova, N.; Timoshenkov, S.; Timoshenkov, V.; Orlov, S.; Iskakov, R.; Prikhodko, O.

    2016-09-01

    Main optical, thermal and mechanical properties of new compositions based on alicyclic polyimide and active bright red 6C synthetic dye have been studied. It was shown that the transmission ratio of the new material in the region of 400-900 nm and 2.0 wt.% dye concentration was around 60-70%. Thermal, mechanical and electrical properties of new colored compositions were comparable with the properties of original polyimide.

  2. Study on process and characterization of high-temperature resistance polyimide composite

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Ling-Ying; Zhao, Wei-Dong; Liu, Han-Yang; Cui, Chao; Guo, Hong-Jun [Aerospace Research Institute of Materials & Processing Technology (No.1 Nan Da Hong Men Road, Fengtai District, Beijing, 100076, P.R., China) (China)

    2016-05-18

    A novel polyimide composite with upper-use temperature of 420°C was prepared by autoclave process. The thermogravimetic analysis and rheological properties of uncured polyimide resin powders were analyzed. The influences of process parameters and post-treatment process on the properties of composites were also investigated. The morphologies of polyimide composites after shear fracture were observed by scanning electron microscope (SEM). The high-temperature resistance of composite was characterized by dynamic mechanical thermal analyzer (DMTA). Results showed that the imidization reaction mainly occurred in the temperature range of 100°C~220°C, and the largest weight loss rate appearing at 145°C indicated a drastic imidization reaction occurred. The melt viscosity of polyimide resin decreased with increasing the temperature between 220°C ∼305°C, and then increased with the increase of temperature due to the molecular crosslinking reactions. The fiber volume contents and void contents could be effectively controlled by applying the pressure step by step. The fiber volume content was sensitive to the initial pressure (P{sub i}) during the imidization. The second-stage pressure (P{sub 2}) and the temperature for applying the P{sub 2} (T{sub 2}) during the imidization had a great effect on the void content of composite. Good mechanical properties and interfacial adhesion of polyimide composite could obtain by optimized process. The post-treatment process can obviously increase the high-temperature resistance of polyimide composite. The polyimide composite treated at 420°C exhibited good retention of mechanical properties at 420°C and had a glass transition temperature (Tg) of 456°C. The retentions of flexible strength, flexible modulus and short beam shear strength of polyimide composite at 420°C were 65%, 84% and 62% respectively.

  3. Effects of Nanoparticles on Properties of Modified Polyimide Epoxy Adhesive

    Institute of Scientific and Technical Information of China (English)

    BA De-ma; MA Shi-ning; QIAO Yu-lin; ZHANG Shi-tang

    2004-01-01

    Polyimide modified epoxy adhesive(J-27H)/nano-SiOx and nano-Al2 O3 nanocomposite were prepared by ball milling treating method. Differential Scanning Calorimetry(DSC)was used to study effects of nanoparticles on curing speed of nanocomposited adhesive, and dynamic mechanical analyzer (DMA) was utilized to analyze the glass transition temperature.Results showed a increase in curing speed of nanocomposites in comparision with the neat J-27H, the curing speed of SiOx/J -27H nanocompositeis higher than Al2O3/J-27H nanocomposite. The curing speed of 6wt% SiOx/ J-27H nanocomposite is six times that of neat J-27H. Glass transition temperature measured for SiOx/ J-27H nanocomposite showed a slight increase compared to the neat J-27H.

  4. Crosslinking-property relationships in PMR polyimide composites. I

    Science.gov (United States)

    Pater, R. H.; Whitley, K.; Morgan, C.; Chang, A.

    1987-01-01

    The thermooxidatively-induced crosslinking/ physical and mechanical property relationships of graphite fiber-reinforced PMR polyimide-matrix composites were studied during isothermal exposure of the composite specimens at 288 C in air for periods of up to 5000 hr. The crosslinking densities due to this treatment were estimated on the basis of the kinetic theory of rubber elasticity and shifts in the glass transition temperature T(g). Several linear relationships are noted between crosslink density and physical and mechanical properties: T(g), initial weight loss, and elevated temperature interlaminar shear strength increase with crosslink density, while initial moisture absorption decreases. After achieving the highest crosslink density, several of the composite properties begin to decrease from their maximum values.

  5. Polyimide Humidity Integrated Sensor Fabricated Using the MEMS Process

    Institute of Scientific and Technical Information of China (English)

    Dianzhong Wen

    2006-01-01

    This paper reports on the fabrication and sensing characteristics of Polyimide-based humidity sensor, based on that, a new integrated circuit of humidity measurement has been designed. It is a novel capacitive-type systems on a chip structure using the MEMS process. The results show that the new sensor presents sensing characteristics over a humidity range from 10%~70% RH at 20℃, and the sensor is able to fabricated together with Ics technology. The result shows that integration of humidity sensor with integrated circuit of humidity measurement is considerably easier when they are built in sensing groove. The appeal of a new structure like this brings the possibility of applications that would require the flexibility of simple screen printing.

  6. Polyimides and their derivatives for gas separation applications

    Energy Technology Data Exchange (ETDEWEB)

    J. R. Klaehn; C.J. Orme; T.J. Luther; E.S. Peterson; Jagoda M. Urban-Klaehn

    2007-07-01

    High performance polymers are of interest for high temperature gas separations, especially for the sequestration of carbon dioxide. A new family of high performance imide polymers (VTEC, RBI Inc.) has been identified as a material class containing the potential building blocks needed for a successful membrane capture material. The VTEC polyimides possess the desired thermal properties (up to 500 °C) and are robust and flexible even after multiple thermal cycles (up to 400 °C). A critical variable when working with the glassy polymers is their moisture content. It has been found that water entrapped within the polymer matrix (either as hydration molecules attached to salts in the polymer, left over solvent, or physisorbed) can also cause the polymer to change dramatically. Additionally presence of molecular water in the polymer’s void volume has been validated through Positron Annihilation Lifetime (PAL) spectroscopy. In this presentation, polymer characterization and gas-separation testing results will be discussed.

  7. A nanometric cushion for enhancing scratch and wear resistance of hard films.

    Science.gov (United States)

    Gotlib-Vainshtein, Katya; Girshevitz, Olga; Sukenik, Chaim N; Barlam, David; Cohen, Sidney R

    2014-01-01

    Scratch resistance and friction are core properties which define the tribological characteristics of materials. Attempts to optimize these quantities at solid surfaces are the subject of intense technological interest. The capability to modulate these surface properties while preserving both the bulk properties of the materials and a well-defined, constant chemical composition of the surface is particularly attractive. We report herein the use of a soft, flexible underlayer to control the scratch resistance of oxide surfaces. Titania films of several nm thickness are coated onto substrates of silicon, kapton, polycarbonate, and polydimethylsiloxane (PDMS). The scratch resistance measured by scanning force microscopy is found to be substrate dependent, diminishing in the order PDMS, kapton/polycarbonate, Si/SiO2. Furthermore, when PDMS is applied as an intermediate layer between a harder substrate and titania, marked improvement in the scratch resistance is achieved. This is shown by quantitative wear tests for silicon or kapton, by coating these substrates with PDMS which is subsequently capped by a titania layer, resulting in enhanced scratch/wear resistance. The physical basis of this effect is explored by means of Finite Element Analysis, and we suggest a model for friction reduction based on the "cushioning effect" of a soft intermediate layer.

  8. The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

    Directory of Open Access Journals (Sweden)

    Yoshimoto Akifumi

    2015-01-01

    Full Text Available These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10−3 to 103 s−1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from − 190 °C to 270°∘C. The flow stress decreased with increasing temperature.

  9. Internal acetylene unit as a cross-link site for polyimides

    Energy Technology Data Exchange (ETDEWEB)

    Takeichi, T.; Tanikawa, M. [Toyohashi Univ. of Technology (Japan)

    1995-12-01

    We have been studying on the cross-linking behavior of internal acetylenes linked meta-meta to aromatic connecting units which were introduced into the polyimide backbone utilizing 3,3`-diaminodiphenylacetylene (m-intA). In this study, we studied on the cross-linking behavior of internal acetylenes linked para-para to aromatic connecting units. The internal acetylene units were introduced into the polyimide backbone by the reaction of 4,4`-diaminodiphenylacetylene (p-intA) with such acid anhydrides as biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). The polyimides showed exotherm on DSC: The onset of the exotherm of p-intA appeared at around 330-390{degrees}C, which is 10-50{degrees}C higher than that of m-intA. The exotherm disappeared after thermal treatment at 400{degrees}C, suggesting the progress of crosslinking between acetylene units. The polyimides cured at 350{degrees}C or 400{degrees}C showed increased Tg and improved physical properties at high temperatures as confirmed by viscoelastic analyses. It was also made clear that polyimides containing p-intA showed higher modulus compared with polyimides containing m-intA, especially when coupled with BPDA and PMDA.

  10. Novel thermally cross-linked polyimide membranes for ethanol dehydration via pervaporation

    KAUST Repository

    Xu, Sheng

    2015-12-01

    © 2015 Elsevier B.V. In this work, two novel carboxyl-containing polyimides, 2,2\\'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-4,4\\'-diaminodiphenylmethane/3,5-diaminobenzoic acid (6FDA-MDA/DABA, FMD) and 3,3\\',4,4\\'-benzophenone tetracarboxylic dianhydride-4,4\\'-diaminodiphenylmethane/3,5-diaminobenzoic acid (BTDA-MDA/DABA, BMD), are synthesized via chemical and thermal imidization methods, respectively, and employed as pervaporation membranes for ethanol dehydration. Chemical structures of the two polyimides are examined by FTIR and TGA to confirm the successful synthesis. A post thermal treatment of the polyimide membranes with the temperature range of 250 to 400. °C is applied, and its effects on the membrane morphology and separation performance are studied and characterized by FTIR, TGA, WXRD, solubility and sorption test. It is believed that the thermal treatment of the carboxyl-containing polyimide membrane at a relative low temperature only leads to the physical annealing, while it may cause the decarboxylation-induced cross-linking at a higher temperature. In addition, the operation temperature in pervaporation is also varied and shown to be an important factor to affect the final membrane performance. Performance benchmarking shows that the developed polyimide membranes both have superior pervaporation performance to most other flat-sheet dense membranes. This work is believed to shed useful insights on polyimide membranes for pervaporation applications.

  11. Molecular dynamics simulations of uniaxial deformation of thermoplastic polyimides.

    Science.gov (United States)

    Nazarychev, V M; Lyulin, A V; Larin, S V; Gurtovenko, A A; Kenny, J M; Lyulin, S V

    2016-05-07

    The results of atomistic molecular-dynamics simulations of mechanical properties of heterocyclic polymer subjected to uniaxial deformation are reported. A new amorphous thermoplastic polyimide R-BAPO with a repeat unit consisting of dianhydride 1,3-bis-(3',4,-dicarboxyphenoxy)diphenyl (dianhydride R) and diamine 4,4'-bis-(4''-aminophenoxy)diphenyloxide (diamine BAPO) was chosen for the simulations. Our primary goal was to establish the impact of various factors (sample preparation method, molecular mass, and cooling and deformation rates) on the elasticity modulus. In particular, we found that the elasticity modulus was only slightly affected by the degree of equilibration, the molecular mass and the size of the simulation box. This is most likely due to the fact that the main contribution to the elasticity modulus is from processes on scales smaller than the entanglement length. Essentially, our simulations reproduce the logarithmic dependence of the elasticity modulus on cooling and deformation rates, which is normally observed in experiments. With the use of the temperature dependence analysis of the elasticity modulus we determined the flow temperature of R-BAPO to be 580 K in line with the experimental data available. Furthermore, we found that the application of high external pressure to the polymer sample during uniaxial deformation can improve the mechanical properties of the polyimide. Overall, the results of our simulations clearly demonstrate that atomistic molecular-dynamics simulations represent a powerful and accurate tool for studying the mechanical properties of heterocyclic polymers and can therefore be useful for the virtual design of new materials, thereby supporting cost-effective synthesis and experimental research.

  12. Anchoring Strength of Thin Aligned-Polymer Films Formed by Liquid Crystalline Monomer

    Science.gov (United States)

    Murashige, Takeshi; Fujikake, Hideo; Ikehata, Seiichiro; Sato, Fumio

    2003-04-01

    We have evaluated the polar anchoring strength of a thin molecule-aligned polymer film formed by a liquid crystalline monomer. The polymer film was obtained by photopolymerization of the monomer oriented by a rubbed polyimide alignment layer in a chamber filled with N2 gas. We fabricated a nematic liquid crystal cell using the thin aligned-polymer films as alignment layers, and then evaluated the anchoring strength of the polymer by measuring the optical retardation curve of the cell driven by voltages. The experimental result showed that the anchoring strength was one order of magnitude lower than that of a conventional rubbed polyimide alignment layer, and decreased with increasing the cure temperature of the monomer film.

  13. Use of the quartz crystal microbalance to determine the monomeric friction coefficient of polyimides

    Science.gov (United States)

    Bechtold, Mary M.

    1995-01-01

    When a thin film of polymer is coated on to a quartz crystal microbalance (QCM), the QCM can be used to detect the rate of increase in weight of the polymer film as the volatile penetrant diffuses into the polymer. From this rate information the diffusion coefficient of the penetrant into the polymer can be computed. Calculations requiring this diffusion coefficient lead to values which approximate the monomeric friction coefficient of the polymer. This project has been concerned with the trial of crystal oscillating circuits suitable for driving polymer coated crystals in an atmosphere of penetrant. For these studies done at room temperature, natural rubber was used as an easily applied polymer that is readily penetrated by toluene vapors, qualities anticipated with polyimides when they are tested at T(g) in the presence of toluene. Three quartz crystal oscillator circuits were tested. The simplest circuit used +/- 5 volt dc and had a transistor to transistor logic (TTL) inverter chip that provides a 180 deg phase shift via a feed back loop. This oscillator circuit was stable but would not drive the crystal when the crystal was coated with polymer and subjected to toluene vapors. Removal of a variable resistor from this circuit increased stability but did not otherwise increase performance. Another driver circuit tested contained a two stage differential input, differential output, wide band video amplifier and also contain a feed back loop. The circuit voltage could not be varied and operated at +/- 5 volts dc; this circuit was also stable but failed to oscillate the polymer coated crystal in an atmosphere saturated with toluene vapors. The third oscillator circuit was of similar construction and relied on the same video amplifier but allowed operation with variable voltage. This circuit would drive the crystal when the crystal was submerged in liquid toluene and when the crystal was coated with polymer and immersed in toluene vapors. The frequency readings

  14. 低热膨胀系数纳米碳化硅/聚酰亚胺复合薄膜的制备与性能%Preparation and properties of nano-SiC/polyimide composite films with low thermal expansion characteristic

    Institute of Scientific and Technical Information of China (English)

    吕静; 党智敏

    2011-01-01

    以原位分散聚合法制备出纳米碳化硅/聚酰亚胺(n-SiC/PI)复合薄膜,采用SEM、热机械分析仪(TMA)、阻抗分析仪和热重分析(TG)研究了所制备薄膜的表面形貌、热膨胀、介电性能及热稳定性。结果表明:SiC粒子均匀分散在PI基体中,复合薄膜的热膨胀系数(CTE)随着SiC含量的增加逐渐减小,SiC质量分数为15%时,CTE降低了11%,且复合膜的热膨胀系数实验值比较接近于Kerner公式的计算值。复合膜的介电常数和介电损耗随着填料含量的变化而变化,但始终维持在较低的范围内,并在相当大的频率范围内保持稳定。%Nano-SiC/Polyimide(n-SiC/PI) composite films were prepared by using in-situ dispersive polymerization.The surface morphology,thermal expansion,dielectric properties and thermal stability of n-SiC/PI were studied by SEM,thermal mechanical analysis(TMA),impedance analyzer and thermal gravimetric analysis(TG) respectively.The results show that n-SiC particles are dispersed in the PI matrix evenly by employing the in-situ polymerization.The coefficient of thermal expansion(CTE) of n-SiC/PI composite films decreases with the increasing of the SiC content,while the experimental data could be analyzed by Kerner model closely.The CTE of PI with n-SiC mass fraction of 15% decrease about 11% than that of the pure PI.The dielectric constant and dielectric loss of films vary with the content of n-SiC fillers,remaining in the lower range and stable in a wide frequency range.

  15. Designed poly(ether-imide)s and fluoro-copoly(ether-imide)s: Synthesis, characterization and their film properties

    Energy Technology Data Exchange (ETDEWEB)

    Vora, Rohitkumar H. [Advanced Polymer Research and Technologies, 505 Cinder Road, Edison, NJ 08820 (United States)]. E-mail: rohitvora@apr-technologies.com; Goh, Suat Hong [Department of Chemistry, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)

    2006-07-25

    Two series of amorphous fluoro-poly(ether-imide) (6F-PEI) and one series of fluoro-coploy(ether-imide) (6F-CoPEI) polymers based on 2,2'-bis(3,4-dicarboxyphenyl) hexafluropropane dianhydride (6FDA) and di-ether-containing diamines: 1,2'-bis(4-aminophenoxy)benzene (o-BAPOB) and 4,4'-bis(4-aminophenoxy)diphenyl sulfone (p-SED) were synthesized. The solution properties, chemical resistance, thermal stability, mechanical properties, thermo-oxidative and hydrolytic stability of selected 6F-PEIs and 6F-CoPEIs were studied. The dielectric constant ({epsilon}') values of 6F-PEI and 6F-CoPEI were estimated by additive group contribution calculation using mathematical equations defined by the Lorentz-Lorenz's theory and the Vogel's theory, and by Vora-Wang equations, respectively. These polymers not only showed excellent electrical properties but also excellent long-term thermo-oxidative stability and reduced water absorption relative to non-fluorinated polyimides. The estimated dielectric constant of these polymers ({epsilon}' < 3.15) were lower than those of commercially available poly(ether-imide) ULTEM[reg] 1000 and polyimides Kapton[reg] H, respectively at 1 kHz. The analytical results are summarized and discussed.

  16. Preparation and enhanced properties of Fe3O4 nanoparticles reinforced polyimide nanocomposites

    Science.gov (United States)

    Ding, Daowei; Yan, Xingru; Zhang, Xi; He, Qingliang; Qiu, Bin; Jiang, Dawei; Wei, Huige; Guo, Jiang; Umar, Ahmad; Sun, Luyi; Wang, Qiang; Khan, Mojammel A.; Young, David P.; Zhang, Xin; Weeks, Brandon; Ho, Thomas C.; Guo, Zhanhu; Wei, Suying

    2015-09-01

    Polyimide (PI) nanocomposite reinforced with Fe3O4 nanoparticles (NPs) at various NPs loadings levels of 5.0, 10.0, 15.0, and 20.0 wt% were prepared. The chemical interactions of the Fe3O4 NPs/PI nanocomposites were characterized using Fourier Transform Infrared (FT-IR) spectroscopy. X-ray Diffraction (XRD) results revealed that the addition of NPs had a significant effect on the crystallization of PI. Scanning electron microscope (SEM) and the atomic force microscope (AFM) were used to characterize the dispersion and surface morphology of the Fe3O4 NPs and the PI nanocomposites. The obtained optical band gap of the nanocomposites characterized using Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS) was decreased with increasing the Fe3O4 loading. Differential scanning calorimetry (DSC) results showed a continuous increase of Tg with increasing the Fe3O4 NPs loading. Some differences were observed in the onset decomposition temperature between the pure PI and nanocomposites since the NPs and the PI matrix were physically entangled together to form the nanocomposites. The contact angle of pure PI was larger than that of Fe3O4/PI nanocomposites films, and increased with increasing the loading of Fe3O4. The degree of swelling was increased with increasing the Fe3O4 loading and the swelling time. The dielectric properties of the nanocomposite were strongly related to the Fe3O4 loading levels. The Fe3O4/PI magnetic property also had been improved with increasing the loading of the magnetic nanoparticles.

  17. Room Temperature Oxide Deposition Approach to Fully Transparent, All-Oxide Thin-Film Transistors.

    Science.gov (United States)

    Rembert, Thomas; Battaglia, Corsin; Anders, André; Javey, Ali

    2015-10-28

    A room temperature cathodic arc deposition technique is used to produce high-mobility ZnO thin films for low voltage thin-film transistors (TFTs) and digital logic inverters. All-oxide, fully transparent devices are fabricated on alkali-free glass and flexible polyimide foil, exhibiting high performance. This provides a practical materials platform for the low-temperature fabrication of all-oxide TFTs on virtually any substrate.

  18. Sputtered iridium oxide films (SIROFs) for neural stimulation electrodes

    OpenAIRE

    Cogan, Stuart F.; Ehrlich, Julia; Plante, Timothy D.; Smirnov, Anton; Shire, Douglas B.; Gingerich, Marcus; Rizzo, Joseph F

    2004-01-01

    Sputtered iridium oxide films (SIROFs) deposited by DC reactive sputtering from an iridium metal target have been characterized in vitro for their potential as neural recording and stimulation electrodes. SIROFs were deposited over gold metallization on flexible multielectrode arrays fabricated on thin (15 µm) polyimide substrates. SIROF thickness and electrode areas of 200–1300 nm and 1960–125600 µm2, respectively, were investigated. The charge-injection capacities of the SIROFs were evaluat...

  19. Electrochemical deposition of diluted magnetic semiconductor ZnMnSe{sub 2} on reduced graphene oxide/polyimide substrate and its properties

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Lingpu; Yu, Shengjiao; Jiang, Yimin; Wang, Chunming, E-mail: wangcm@lzu.edu.cn

    2014-10-01

    Highlights: • The flexible reduced graphene/polyimide conductive substrate was made. • The ZnMnSe{sub 2} semiconductor has special porous structure. • The ZnMnSe{sub 2} has remarkable photoelectric property, the potential difference is 0.27 V. • The semiconductor ZnMnSe{sub 2} has magnetism, and the M{sub s} is 1.53 emu cm{sup −3}. - Abstract: Diluted magnetic semiconductor ZnMnSe{sub 2} has been synthesized on reduced graphene oxide/polyimide (rGO/PI) substrate by a simple electrochemical method. The structure, surface morphology, magnetism and photoelectric property of ZnMnSe{sub 2} were examined. For comparison, ZnSe and MnSe were also prepared by electrochemical deposition. Porous structure of ZnMnSe{sub 2} was obtained, and the porous structure was consisted of nanosheets. The atomic ratio of Zn, Mn and Se was measured to be 1:1:2 by X-ray photoelectron spectra and energy-dispersive X-ray spectroscopy. The high resolution transmission electron microscopy and X-ray Powder Diffraction pattern confirmed the preferred crystal growth orientation was the (1 1 1) direction. The absorption spectrum provided a band gap of 2.4 eV. Open-circuit potential measurement indicated that ZnMnSe{sub 2} composite film was a good p-type semiconductor material. The photoelectrical phenomena of ZnSe, MnSe and ZnMnSe{sub 2} were observed, and the optoelectronic property of ZnMnSe{sub 2} was the best, the potential difference was 0.27 V. Besides, the ZnMnSe{sub 2} composite film had prominent magnetism, and it was ferromagnetism material. These results indicated that rGO/PI–ZnMnSe{sub 2} composite film by electrochemical deposition was a promising ferromagnetism semiconductor.

  20. Recent developments of ion beam induced luminescence: radiation hardness study of thin film plastic scintillators

    Science.gov (United States)

    Quaranta, Alberto

    2005-10-01

    Ion beam induced luminescence (IBIL) measurements have been performed on thin film scintillators based on polyvinyltoluene (PVT) and 6FDA-DAD and BPDA-3F polyimides with H+ (1.85 MeV) and He+ (1.8-2.2 MeV) ion beams. The radiation hardness of the undoped polymers has been verified to depend mainly on the deposited energy density, polyimides exhibiting a higher resistance with respect to PVT. In PVT a new fluorescence band, attributed to the radical precursors of the network crosslinking, has been observed. The efficiency of doped polymers degradates with a higher rate, depending on the dye intrinsic lability. At high radiation fluences, the relative efficiency to NE102 of doped polyimides scintillators increases owing to the intrinsic host improved resistance.

  1. Novel 6FDA-based polyimides derived from sterically hindered Tröger's base diamines: Synthesis and gas permeation properties

    KAUST Repository

    Ghanem, Bader

    2016-04-30

    Two novel Tröger\\'s base-based di-o-substituted diamine monomers were synthesized and used to prepare two intrinsically microporous 6FDA-based polyimides (PIM-PI-TB-1 and PIM-PI-TB-2) with high molecular weight, high thermal stability and excellent solubility in common organic solvents. Compared to previously reported methods for preparing TB-based diamines, which are based on reduction of dimerized nitro-substituted anilines or condensation of phenylenediamine derivatives with dianhydrides, the novel protocol can be used to prepare different functionalized TB-based diamine monomers from a wide variety of aniline derivatives. PIM-PI-TB-1 (made from 6FDA and dibromo-tetramethyl-substituted TB diamine) and PIM-PI-TB-2 (made from 6FDA and tetramethyl-substituted TB diamine) are intrinsically microporous polymers with high BET surface areas of 440 m2/g and 580 m2/g, respectively. Pure-gas permeability coefficients of He, H2, N2, O2, CH4, and CO2 were measured at 35 °C and 2 bar for fresh and 180 days aged films. Both TB-based polyimides exhibited high gas permeability with moderate selectivity. The gas permeability dropped significantly coupled with a moderate increase in selectivity after long-term physical aging of 180 days.

  2. Design and Synthesis of Polyimides Based on Carbocyclic Pseudo-Tröger’s Base-Derived Dianhydrides for Membrane Gas Separation Applications

    KAUST Repository

    Ma, Xiaohua

    2017-07-24

    Two novel carbocyclic pseudo-Tröger’s base-derived dianhydrides, 5,6,11,12-tetrahydro-5,11-methanodibenzo[a,e][8]annulene-2,3,8,9-tetracarboxylic anhydride (CTB1) and its dione-substituted analogue 6,12-dioxo-5,6,11,12-tetrahydro-5,11-methanodibenzo[a,e][8]annulene-2,3,8,9-tetracarboxylic dianhydride (CTB2), were made and used for the synthesis of soluble polyimides of intrinsic microporosity with 3,3′-dimethylnaphthidine (DMN). The polyimides CTB1-DMN and CTB2-DMN exhibited excellent thermal stability of ∼500 °C and high BET surface areas of 580 and 469 m2 g–1, respectively. A freshly made dione-substituted CTB2-DMN membrane demonstrated promising gas separation performance with O2 permeability of 206 barrer and O2/N2 selectivity of 5.2. A higher O2 permeability of 320 barrer and lower O2/N2 selectivity of 4.2 were observed for a fresh CTB1-DMN film due to its higher surface area and less tightly packed structure as indicated by weaker charge-transfer complex interactions. Physical aging over 60 days resulted in reduction in gas permeability and moderately enhanced selectivity. CTB2-DMN exhibited notable performance with gas permeation data located between the 2008 and 2015 permeability/selectivity upper bounds for O2/N2 and H2/CH4.

  3. NOVEL POLYMER WIDE VIEWING ANGLE COMPENSATION FILMS FOR LIQUID CRYSTAL DISPLAYS (LCDS)

    Institute of Scientific and Technical Information of China (English)

    Jason J.Ge; Bruce F.Li; Frank W.Harris; Stephen Z.D.Cheng

    2003-01-01

    We report on generating uniaxial negative birefringent compensation films, made of specifically designed polyimides. These polymers were synthesized via a polycondensation of dianhydride [such as 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride] and 2,2′-bis(trifiuoromethyl)-4,4′-diaminobiphenyl. The uniaxial negative birefiingent (nx =ny > nz) polyimide substrates are achieved using a solution-casting method in conventional solvents, which exhibit the desirable optical phase retardation [(nx - nz) x d] values from 50 to 400 nm varying with the film thickness. In these polyimide films, the long chain rigid molecules adopt intrinsic planar orientation. In detail, the majority of phenylene-imide rings and phenylenes preferentially adopt nearly planar conformations parallel to the film substrate. In addition, these films also possess high transparency (or transmittance) and little color shift. The unique color dispersion curve indicates that this type of materials is very suitable for the applications in LCDs due to an excellent mimic for the retardation color dispersion curve with respect to LC molecules. Significantly low in-plane retardation (< 1 nm) allows this new technology based film to achieve sufficiently high contrast ratio while highly negative retardation dramatically suppresses the gray scale inversion to improve the viewing angle performance in a variety of new mode LCDs.

  4. The Relation Between Structure-Performance of Thin Film Composite Membranes and the Tools Used for Their Fabrication Method

    DEFF Research Database (Denmark)

    Briceno, Kelly; Javakhishvili, Irakli; Guo, Haofei

    For more than 30 years polyimides (PA) have been one of the main polymers for the fabrication of thin film composite membranes. Several researchers have assessed the main fabrication variables that influence the final structure of the polyamide layers including monomer concentration, solvents...

  5. Structural studies of ultrathin organic films

    Science.gov (United States)

    Yim, Hyun

    1998-11-01

    Ultrathin organic films have been a focus of research due to the growing interest in optoelectronics and molecular electronics. In both areas, it is believed that self-assembled (SA) films and Langmuir-Blodgett (LB) films may provide the desired control of order at the molecular level. The tethering of polyglutamate molecules to surfaces is of special interest due to nonlinear optical properties which can be achieved when the molecules are oriented. The tethering of poly(benzyl-L-glutamate) to silicon has been done by polymerization of benzyl-L-glutamate-N-carboxyanhydride using self-assembled monolayers with various concentrations of amino end groups as initiating layers. X-ray reflectivity results show that a minimum concentration of initiator sites on the surface is required. The second tethering system is a polystyrene brush. The polystyrene brush is expected to give strong sensitivity to solvent swelling. The structure of the polystyrene brush, which was chemically grafted to a substrate, in poor solvent and its change at different temperatures were investigated by neutron reflectometry. When temperature increases up to 30sp°C, both the thickness and roughness increase greatly, which indicates that the polystyrene brush changes from a collapsed state to a theta state. Hairy-rod polyimide molecules are of interest due to their interesting physical properties. Multilayer films of preformed polyimide molecules (6FDA-C18) have been obtained for the first time by the LB technique. The multilayer films do not display a distinctively periodic structure. Upon annealing for a few hours at 180sp°C, the structure relaxes slightly. The alkyl side chain substituted polyimides (BACBF/BPDA) can form metastable monolayers for which the pressure-area isotherms vary markedly with side chain length. For the polyimide with octadecyl side chains, a sharp reduction in zero pressure area occurs between 20 and 24sp°C, suggesting an important change in side chain mobility

  6. Fracture and Delamination of Chromium Thin Films on Polymer Substrates

    Science.gov (United States)

    Cordill, M. J.; Taylor, A.; Schalko, J.; Dehm, G.

    2010-04-01

    New emerging technologies in the field of flexible electronic devices require that metal films adhere well and flex with polymer substrates. Common thin film materials used for these applications include copper (Cu) with an adhesion interlayer of chromium (Cr). Copper can be quite ductile and easily move with the polymer substrate. However, Cr is more brittle and fractures at lower strains than Cu. This study aims to examine the fracture and subsequent buckling and delamination of strained Cr films on polyimide (PI). In-situ scanning electron microscope (SEM) straining is used to systematically study the influence of film thickness on fracture and buckling strains. Film fracture and delamination depend on film thickness, and increases in crack and buckle density with decreasing thickness are explored by a shear lag model.

  7. Development of gold induced surface plasmon enhanced CIGS absorption layer on polyimide substrate

    Science.gov (United States)

    Park, Seong-Un; Sharma, Rahul; Sim, Jae-Kwan; Baek, Byung Joon; Ahn, Haeng-Kwun; Kim, Jin Soo; Lee, Cheul-Ro

    2013-09-01

    Localized surface plasmon resonance (LSPR) with metal nanoparticles is the promising phenomenon to increase light absorption by trapping light in thin film solar cells. In this study we demonstrate a successful LSPR effect with gold (Au) nanoparticles onto the Cu(In,Ga)Se2 (CIGS) absorption layer. First, the CIGS absorber layers is fabricated onto the Mo coated polyimide (PI) substrate by using two stage process as DC sputtering of CIG thin film followed by the selenization at 400 °C. Finally, the Au nanoparticles are deposited onto the CIGS layer with increasing particles size from 4-15 nm by using sputter coater for 10-120 s. The X-ray diffraction (XRD) patterns confirm the formation of CIGS/Au nanocomposite structure with prominent peak shift of CIGS reflections and increasing intensity for Au phase. The CIGS/Au nanocomposite morphologies with Au particle size distribution uniformity and surface coverage is examined under ultra-high resolution field effect scanning electron microscope (UHR-FESEM). A peak at 176 cm-1 in Raman spectra, associated with the “A1” mode of lattice vibration for the attributed to the pure chalcopyrite structure. The secondary ion mass spectroscopy (SIMS) showed ∼200 nm depth converge of Au nanoparticles into the CIGS absorption layer. The optical properties as transmittance, reflectance and absorbance of CIGS/Au layers were found to expand in the infrared region and the LSPR effect is the most prominent for Au particles (5-7 nm) deposited for 60 s. The absorption coefficient and band gap measurement also confirms that the LSPR effect for 5-7 nm Au particles with band gap improvement from 1.31 to 1.52 eV for CIGS/Au layer as the defect density decreases due to the deposition of Au nanoparticles onto the CIGS layer. Such LSPR effect in CIGS/Au nanocomposite absorption layer will be a key parameter to further improve performance of the solar cell.

  8. Development of gold induced surface plasmon enhanced CIGS absorption layer on polyimide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seong-Un; Sharma, Rahul; Sim, Jae-Kwan; Baek, Byung Joon; Ahn, Haeng-Kwun; Kim, Jin Soo; Lee, Cheul-Ro, E-mail: crlee7@jbnu.ac.kr

    2013-09-01

    Localized surface plasmon resonance (LSPR) with metal nanoparticles is the promising phenomenon to increase light absorption by trapping light in thin film solar cells. In this study we demonstrate a successful LSPR effect with gold (Au) nanoparticles onto the Cu(In,Ga)Se{sub 2} (CIGS) absorption layer. First, the CIGS absorber layers is fabricated onto the Mo coated polyimide (PI) substrate by using two stage process as DC sputtering of CIG thin film followed by the selenization at 400 °C. Finally, the Au nanoparticles are deposited onto the CIGS layer with increasing particles size from 4–15 nm by using sputter coater for 10–120 s. The X-ray diffraction (XRD) patterns confirm the formation of CIGS/Au nanocomposite structure with prominent peak shift of CIGS reflections and increasing intensity for Au phase. The CIGS/Au nanocomposite morphologies with Au particle size distribution uniformity and surface coverage is examined under ultra-high resolution field effect scanning electron microscope (UHR-FESEM). A peak at 176 cm{sup −1} in Raman spectra, associated with the “A1” mode of lattice vibration for the attributed to the pure chalcopyrite structure. The secondary ion mass spectroscopy (SIMS) showed ∼200 nm depth converge of Au nanoparticles into the CIGS absorption layer. The optical properties as transmittance, reflectance and absorbance of CIGS/Au layers were found to expand in the infrared region and the LSPR effect is the most prominent for Au particles (5–7 nm) deposited for 60 s. The absorption coefficient and band gap measurement also confirms that the LSPR effect for 5–7 nm Au particles with band gap improvement from 1.31 to 1.52 eV for CIGS/Au layer as the defect density decreases due to the deposition of Au nanoparticles onto the CIGS layer. Such LSPR effect in CIGS/Au nanocomposite absorption layer will be a key parameter to further improve performance of the solar cell.

  9. Study of the degradation process of polyimide induced by high energetic ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Severin, Daniel

    2008-09-19

    The dissertation focuses on the radiation hardness of Kapton under extreme radiation environment conditions. To study ion-beam induced modifications, Kapton foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (e.g. Ti, Mo, Au, and U) within a large fluence regime (1 x 10{sup 10}-5 x 10{sup 12} ions/cm{sup 2}). The irradiated Kapton foils were analysed by means of infrared and UV/Vis spectroscopy, tensile strength measurement, mass loss analysis, and dielectric relaxation spectroscopy. For testing the radiation stability of Kapton at the cryogenic operation temperature (5-10 K) of the superconducting magnets, additional irradiation experiments were performed at the Grand Accelerateur National d' Ions Lourds (GANIL, France) focusing on the online analysis of the outgassing process of small volatile degradation fragments. The investigations of the electrical properties analysed by dielectric relaxation spectroscopy exhibit a different trend: high fluence irradiations with light ions (e.g. Ti) lead to a slight increase of the conductivity, whereas heavy ions (e.g. Sm, Au) cause a drastic change already in the fluence regime of nonoverlapping tracks (5 x 10{sup 10} ions/cm{sup 2}). Online analysis of the outgassing process during irradiation at cryogenic temperatures shows the release of a variety of small gaseous molecules (e.g. CO, CO{sub 2}, and short hydro carbons). Also a small amount of large polymer fragments is identified. The results allow the following conclusions which are of special interest for the application of Kapton as insulating material in a high-energetic particle radiation environment. a) The material degradation measured with the optical spectroscopy and tensile strength tests are scalable with the dose deposited by the ions. The high correlation of the results allows the prediction of the mechanical degradation with the simple and non-destructive infrared spectroscopy. The degradation curve points to a

  10. Synthesis of aromatic polyimides with sulfone diamine moieties for a novel membrane oxygenator.

    Science.gov (United States)

    Kawakami, H; Nagaoka, S

    1995-01-01

    The authors have synthesized soluble aromatic polyimides derived from 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 3,3'- or 4,4'-diamino-diphenylsulfone (m-DDS or p-DDS) to develop a novel membrane oxygenator. Asymmetric gas exchange membranes for the oxygenator were prepared by a dry/wet phase inversion process. The resulting membrane structure consisted of an ultrathin, selective, and defect free skin layer supported by a porous substructure. The membranes exhibited extremely high gas flux and selectivity. CO2 flux through the polyimide membranes used in this study increased with a decrease in CO2 pressure and was in accordance with the dual mode transport described by a combination of the Henry and Langmuir modes. This indicates that CO2 is selectively removed from the membranes at low CO2 pressure as compared with presently available materials for membrane oxygenators, such as polydimethylsiloxane and polypropylene. The number of platelets adherent to the surface of the polyimide were significantly smaller than those on polydimethylsiloxane and polypropylene, and the deformation and aggregation of platelets on polyimide were not observed. These findings suggest that aromatic polyimides with sulfone diamine moieties are promising membrane materials for an oxygenator.

  11. Formation of silver nanoclusters in transparent polyimides by Ag-K ion-exchange process

    Science.gov (United States)

    Carturan, S.; Quaranta, A.; Bonafini, M.; Vomiero, A.; Maggioni, G.; Mattei, G.; de Julián Fernández, C.; Bersani, M.; Mazzoldi, P.; Della Mea, G.

    2007-05-01

    Silver nanoclusters embedded in two transparent fluorinated polyimides, 4,4'-hexafluoroisopropylidene diphthalic anhydride 2,3,5,6-tetramethyl paraphenylene diamine (6FDA-DAD) and 3,3',4,4' biphenyltetracarboxylic acid dianhydride 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane (BPDA-3F), have been produced by surface modification with KOH aqueous solution followed by K-assisted Ag doping and thermal reduction in hydrogen atmosphere. The reaction rate of the nucleophilic hydrolysis in KOH, studied by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectrometry (RBS), depends on the polyimide chemical structure. After ion-exchange in AgNO{3} solution and subsequent annealing, the polyimide structure recovery was monitored by FT-IR whereas the characteristic surface plasmon absorption band of silver nanoparticles was evidenced by optical absorption measurements. The structure of silver nanoclusters as related to size and size distribution in the different polyimide matrices was thoroughly investigated by Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The collected data evidenced a uniform distribution of Ag clusters of nanometric size after thermal treatment at 300 circC in both polyimides. For the same ion-exchange treatment parameters and annealing temperature, XRD analyses evidenced the presence of crystallites with similar sizes.

  12. PERVAPORATION SEPARATION FOR TOLUENE/n-HEPTANE MIXTURE BY POLYIMIDE MEMBRANES CONTAINING FLUORINE

    Institute of Scientific and Technical Information of China (English)

    Hong Ye; Ji-ding Li; Yang-zheng Lin; Jian Chen; Cui-xian Chen

    2008-01-01

    Five kinds of polyimides were synthesized using five dianhydrides (including 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl] propane dianhydride (BPADA), 3,3',4,4'-diphenyisulfone-tetracarboxylic dianhydride (DSDA), 4,4'(hexafluoroisopropylidene)-diphthalic anhydride (6FDA),1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA),and 4,4'-oxydiphthlic dianhydride (ODPA)) and 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane (BDAF) via the twostep method that included polyaddition to form the polyamic acid and subsequent chemical imidization at ambient temperature.The structures of polyimides were characterized by FTIR and NMR.The thermal properties were characterized by DSC and TGA.All five kinds of polyimides showed good thermal properties and solubility in organic solvents such as DMF,DMAc,NMP and THF at room temperature.The pervaporation (PV) experiments of polyimides for toluene/n-heptane mixture were carried out,and all the polyimides showed selective permeation towards toluene.The fluxes of 6FDA-BDAF,DSDA-BDAF,HQDPA-BDAF and ODPA-BDAF at 80℃ were 1.08,0.96,1.77 and 0.10 kg-μm/(m2.h),and the separation factors were 5.44,1.64,1.28 and 11.44,respectively.The increasing feed temperature resulted in higher flux and lower separation factor of the 6FDA-BDAF membrane.

  13. Study of dynamics of diffusion and cluster formation of copper deposition on polyimide by optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.Y.; Shen, Y.R. (Department of Physics, University of California, Berkeley, California 94720 (United States)); Soane, D.S. (Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States))

    1992-03-15

    We demonstrate that optical second-harmonic generation (SHG) can be successfully used for {ital in} {ital situ} study of metal/polymer interfaces. With this SHG technique, Cu cluster formation on polyimide by surface diffusion and Cu diffusion into polyimide have been investigated. The diffusion coefficients of Cu clusters into polyimide at various temperatures have been determined from the measured decay of SHG signal with time. The effects of temperature, cluster size, and surface modification on diffusion have also been examined. For {ital T} {lt} {ital T}{sub {ital g}}, the surface diffusion of Cu on polyimide to form clusters dominates over the diffusion into the bulk. The latter process becomes competitive with increasing temperature. When {ital T} {gt} {ital T}{sub {ital g}}, few large-size Cu clusters can be formed on the polyimide surface. Cu diffusion into polyimide bulk can be greatly impeded by either a monolayer of Ti or by Cu clusters implanted in polyimide beforehand. In this case, Cu can wet the modified surface and form an interface between Cu and polyimide with good adhesion.

  14. Thermoluminescent characterization of thin films of aluminium oxide submitted to beta and gamma radiation; Caracterizacion termoluminiscente de peliculas delgadas de oxido de aluminio sometidas a radiacion beta y gamma

    Energy Technology Data Exchange (ETDEWEB)

    Villagran, E.; Escobar A, L.; Camps, E.; Gonzalez, P.R.; Martinez A, L. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    By mean of the laser ablation technique, thin films of aluminium oxide have been deposited on kapton substrates. These films present thermoluminescent response (Tl) when they are exposed to beta and gamma radiation. The brilliance curves show two peaks between 112 C and 180 C. A dose-response relationship study was realized and the Tl kinetic parameters were determined using the computerized deconvolution of the brilliance curve (CGCD). The thin films of aluminium oxide have potential applications as ultra.thin radiation dosemeters. (Author)

  15. Dielectric relaxation dynamics of high-temperature piezoelectric polyimide copolymers

    Science.gov (United States)

    Maceiras, A.; Costa, C. M.; Lopes, A. C.; San Sebastián, M.; Laza, J. M.; Vilas, J. L.; Ribelles, J. L. Gómez; Sabater i Serra, R.; Andrio Balado, A.; Lanceros-Méndez, S.; León, L. M.

    2015-08-01

    Polyimide copolymers have been prepared based on different diamines as comonomers: a diamine without CN groups and a novel synthesized diamine with two CN groups prepared by polycondensation reaction followed by thermal cyclodehydration. Dielectric spectroscopy measurements were performed, and the dielectric complex function, ac conductivity and electric modulus of the copolymers were investigated as a function of CN group content in the frequency range from 0.1 to 107 Hz at temperatures from 25 to 260 °C. For all samples and temperatures above 150 °C, the dielectric constant increases with increasing temperature due to increasing conductivity. The α-relaxation is just detected for the sample without CN groups, being this relaxation overlapped by the electrical conductivity contributions in the remaining samples. For the copolymer samples and the polymer with CN groups, an important Maxwell-Wagner-Sillars contribution is detected. The mechanisms responsible for the dielectric relaxation, conduction process and electric modulus response have been discussed as a function of the CN group content present in the samples.

  16. Fabrication of polyimide based microfluidic channels for biosensor devices

    Science.gov (United States)

    Zulfiqar, Azeem; Pfreundt, Andrea; Svendsen, Winnie Edith; Dimaki, Maria

    2015-03-01

    The ever-increasing complexity of the fabrication process of Point-of-care (POC) devices, due to high demand of functional versatility, compact size and ease-of-use, emphasizes the need of multifunctional materials that can be used to simplify this process. Polymers, currently in use for the fabrication of the often needed microfluidic channels, have limitations in terms of their physicochemical properties. Therefore, the use of a multipurpose biocompatible material with better resistance to the chemical, thermal and electrical environment, along with capability of forming closed channel microfluidics is inevitable. This paper demonstrates a novel technique of fabricating microfluidic devices using polyimide (PI) which fulfills the aforementioned properties criteria. A fabrication process to pattern microfluidic channels, using partially cured PI, has been developed by using a dry etching method. The etching parameters are optimized and compared to those used for fully cured PI. Moreover, the formation of closed microfluidic channel on wafer level by bonding two partially cured PI layers or a partially cured PI to glass with high bond strength has been demonstrated. The reproducibility in uniformity of PI is also compared to the most commonly used SU8 polymer, which is a near UV sensitive epoxy resin. The potential applications of PI processing are POC and biosensor devices integrated with microelectronics.

  17. Photomechanically coupled viscoelasticity of azobenzene polyimide polymer networks

    Science.gov (United States)

    Roberts, Dennice; Worden, Matt; Chowdhury, Sadiyah; Oates, William S.

    2017-07-01

    Polyimide-based azobenzene polymer networks have demonstrated superior photomechanical performance over more conventional azobenzene-doped pendent and cross-linked polyacrylate networks. These materials exhibit larger yield stress and glass transition temperatures and thus provide robustness for active control of adaptive structures directly with polarized, visible light. Whereas photochemical reactions clearly lead to deformation, as indicated by a rotation of a linear polarized light source, temperature and viscoelasticity can also influence deformation and complicate interpretation of the photostrictive and shape memory constitutive behavior. To better understand this behavior we develop a rate-dependent constitutive model and experimentally quantify the material behavior in these materials. The rate dependent deformation induced in these materials is quantified experimentally through photomechanical stress measurements and infrared camera measurements. Bayesian uncertainty analysis is used to assess the role of internal polymer network evolution and azobenzene excitation on both thermomechanical and photomechanical deformation in the presence polarized light of different orientations. A modified Arrhenius relation is proposed and validated using Bayesian statistics which provide connections between free volume, shape memory, and polarized light.

  18. An improved processible acetylene-terminated polyimide for composites

    Science.gov (United States)

    Landis, A. L.; Naselow, A. B.

    1985-01-01

    The newest member of a family of thermosetting acetylene-substituted polyimide oligomers is HR600P. This oligomer is the isoimide version of the oligomer known as HR600P and Thermid 600. Although both types of material yield the same heat resistant end products after cure, HR600P has much superior processing characteristics. This attributed to its lower melting temperature (160 + or - 10 C, 320 + or - 20 F) in contrast to 202 C (396 F) for Thermid MC-600, its longer gel time at its processing temperature (16 to 30 minutes bvs 3 minutes), and its excellent solubility in low boiling solvents such as tetrahydrofuran, glymes, or 4:1 methyl ethyl ketone/toluene mixtures. These advantages provide more acceptable coating and impregnation procedures, allow for more complete removal at lower temperatures, provide a longer pot life or working time, and allow composite structure fabrication in conventional autoclaves used for epoxy composite curing. The excellent processing characteristics of HR600P allow its use in large area laminated structures, structural composites, and molding compositions.

  19. Novel reusable porous polyimide fibers for hot-oil adsorption.

    Science.gov (United States)

    Tian, Lidong; Zhang, Chongyin; He, Xiaowei; Guo, Yongqiang; Qiao, Mingtao; Gu, Junwei; Zhang, Qiuyu

    2017-10-15

    The development of oil sorbents with high thermal stability, adsorption capacity, reusability and recoverability is of great significance for hot oil leakage protection, especially for oil spillage of oil refinery, petrochemical industry and cars. In our work, highly efficient hot oil adsorption of polyimide (PI) fibers with excellent thermal stability was successfully prepared by a facile electrospinning method followed by post-treatment. The corresponding morphologies, structures and oil adsorption properties of as-prepared PI fibers at different temperatures were analyzed and characterized. Results showed that PI fibers presented a stable morphology and pore structure at 200°C. The oil adsorption capacity of porous PI fibers for hot motor oil (200°C) was about 57.4gg(-1), higher than that of PI fibers (32.7gg(-1)) with non-porous structure for the motor oil at room temperature. Even after ten adsorption cycles, porous PI fibers still maintained a comparable oil sorption capacity (oil retention of 4.2%). The obtained porous PI fibers exhibited excellent hot oil adsorption capacity, reusability and recoverability, which would broaden the application of electrospun fibers in oil spill cleanup and further provide a versatile platform for exploring the technologies of nanofibers in hot oil adsorption field. Copyright © 2017. Published by Elsevier B.V.

  20. Ultrathin thermoacoustic nanobridge loudspeakers from ALD on polyimide

    Science.gov (United States)

    Brown, J. J.; Moore, N. C.; Supekar, O. D.; Gertsch, J. C.; Bright, V. M.

    2016-11-01

    The recent development of low-temperature (sound production from thermoacoustic loudspeakers fabricated from suspended tungsten nanobridges formed by ALD. Additionally, this paper develops an approach to lumped-element modeling for design of thermoacoustic nanodevices and relates the near-field plane wave model of individual transducer beams to the far-field spherical wave sound pressure that can be measured with standard experimental techniques. Arrays of suspended nanobridges with 25.8 nm thickness and sizes as small as 17 μm × 2 μm have been fabricated and demonstrated to produce audible sound using the thermoacoustic effect. The nanobridges were fabricated by ALD of 6.5 nm Al2O3 and 19.3 nm tungsten on sacrificial polyimide, with ALD performed at 130 °C and patterned by standard photolithography. The maximum observed loudspeaker sound pressure level (SPL) is 104 dB, measured at 20 kHz, 9.71 W input power, and 1 cm measurement distance, providing a loudspeaker sensitivity value of ∼64.6 dB SPL/1 mW. Sound production efficiency was measured to vary proportional to frequency f 3 and was directly proportional to input power. The devices in this paper demonstrate industrially feasible nanofabrication of thermoacoustic transducers and a sound production mechanism pertinent to submicron-scale device engineering.

  1. Thermal analysis and its application in evaluation of fluorinated polyimide membranes for gas separation

    KAUST Repository

    Qiu, Wulin

    2011-08-01

    Seven polyimides based on (4,4′-hexafluoroisopropylidene) diphthalic anhydride, 6FDA, with different chemical structures were synthesized in a single pot two-step procedure by first producing a high molecular weight polyamic acid (PAA), followed by reaction with acetic anhydride to produce polyimide (PI). The resulting polymers were characterized using thermal analysis techniques including TGA, derivative weight analysis, TGA-MS, and DSC. The decarboxylation-induced thermal cross-linking, ester cross-linking through a diol, and ion-exchange reactions of selected polyimide membranes were investigated. Cross-linking of polymer membranes was confirmed by solubility tests and CO 2 permeability measurements. The thermal analysis provides simple and timesaving opportunities to characterize the polymer properties, the ability to optimize polymer cross-linking conditions, and to monitor polymer functionalization to develop high performance polymeric membranes for gas separations. © 2011 Elsevier Ltd. All rights reserved.

  2. Facile and efficient route to polyimide-TiO2 nanocomposite coating onto carbon fiber.

    Science.gov (United States)

    He, Shuqing; Lu, Chunxiang; Zhang, Shouchun

    2011-12-01

    Polyamic acid-TiO(2) hybrid colloid emulsion with an average particle size of 200 nm was formed by dispersing nano-TiO(2) into polyamic acid colloidal emulsion. The polyimide-TiO(2) nanocomposite was coated onto carbon fiber by electrophoretic deposition. The primary properties of polyamic acid-TiO(2) hybrid colloid emulsion and polyimide-TiO(2) nanocomposite coating onto carbon fiber were characterized using laser scattering, ZetaPlus particle sizing, transmission electron microscopy, field-emission scanning electron microscope, Fourier transforms infrared spectroscopy, and X-ray Diffraction analysis. The results indicated that the small amount of nano-TiO(2) would be effectively dispersed in polyamic acid colloidal particles. The polyimide-TiO(2) hybrid nanocomposite coating carbon fiber sheet displayed an excellent photodegradation performance of methyl orange, which could be degraded more than 70 wt % after 10 cycles.

  3. Fabricating fluorinated polyimide optical waveguide by CO2 laser direct-writing

    Science.gov (United States)

    Jin, Xi; Zhu, Daqing; Zeng, Xiaoyan

    2008-12-01

    Fluorinated polyimide waveguides were fabricated by CO2 laser direct-writing. The poly(amic acid) micro-region exposed by CO2 laser beam was measured with FT-IR micro-spectroscopy. The FT-IR spectra indicated that the laser imidized polyimide was semicrystalline, and the imidization degree of scanned micro-region increased with the rising of output laser power. The increased aspect ratio of waveguide and smoothness of surface can be achieved by increasing the pre-cured temperature (below 120 °C) and writing rate, and optimizing laser power and the distance between the lens and the annular aperture. The guided light was clearly confined to the core of the fabricated waveguide, which means this technique can be used for fluorinated polyimide waveguide fabrication.

  4. A High T(sub g) PMR Polyimide Composites (DMBZ-15)

    Science.gov (United States)

    Chuang, Kathy C.; Bowles, Kenneth J.; Papadopoulos, Demitrios S.; Hardy-Green, DeNise; Mccorkle, Linda

    2000-01-01

    A high T(sub g) thermosetting PMR-type polyimide, designated as DMBZ-15, was developed by replacing methylene dianline (MDA) in PMR-15 with 2,2'-dimethylbenzidine. Polyimide/carbon fiber (T650-35) composites were fabricated from a formulation of 3,3', 4,4'-benzophenonetetracarboxylic acid dimethyl ester (BTDE) and 2,2'-dimethylbenzidine (DMBZ), along with nadic ester (NE) as the endcap. DMBZ-15 displays a higher glass transition temperature (T(sub g) = 414 C) than PMR-15 (T(sub g) = 345 C), and thus retains better mechanical properties for brief exposure above 400 C. The physical properties and longterm thermo-oxidative stability of the DMBZ-15 polyimide/carbon fiber composites are also compared to that of PMR-15.

  5. Gas separation performance of 6FDA-based polyimides with different chemical structures

    KAUST Repository

    Qiu, Wulin

    2013-10-01

    This work reports the gas separation performance of several 6FDA-based polyimides with different chemical structures, to correlate chemical structure with gas transport properties with a special focus on CO2 and CH 4 transport and plasticization stability of the polyimides membranes relevant to natural gas purification. The consideration of the other gases (He, O2 and N2) provided additional insights regarding effects of backbone structure on detailed penetrant properties. The polyimides studied include 6FDA-DAM, 6FDA-mPDA, 6FDA-DABA, 6FDA-DAM:DABA (3:2), 6FDA-DAM:mPDA (3:2) and 6FDA-mPDA:DABA (3:2). Both pure and binary gas permeation were investigated. The packing density, which is tunable by adjusting monomer type and composition of the various samples, correlated with transport permeability and selectivity. The separation performance of the polyimides for various gas pairs were also plotted for comparison to the upper bound curves, and it was found that this family of materials shows attractive performance. The CO 2 plasticization responses for the un-cross-linked polyimides showed good plasticization resistance to CO2/CH4 mixed gas with 10% CO2; however, only the cross-linked polyimides showed good plasticization resistance under aggressive gas feed conditions (CO 2/CH4 mixed gas with 50% CO2 or pure CO 2). For future work, asymmetric hollow fibers and carbon molecular sieve membranes based on the most attractive members of the family will be considered. © 2013 Elsevier Ltd. All rights reserved.

  6. Preparation and characterization of novel thermoset polyimide and polyimide-peo doped with LiCF3SO3

    Directory of Open Access Journals (Sweden)

    M. H. Ugur

    2014-02-01

    Full Text Available This paper deals with the synthesis and characterization of a new type of anhydrous ionic conducting lithium doped membranes consist of polyimide (PI, poly (ethylene oxide (PEO and lithium trifluoromethanesulfonate (LiCF3SO3 for solid polymer electrolyte (SPE. For this purpose, different molar ratios of lithium salt (Li-salt solution are added into poly (amic acid (PAA intermediate prepared from the reaction of 3,3',4,4'-benzophenon tetracarboxylic dianhydride (BTDA and 4,4'-oxydianiline (ODA. PEO is incorporated into PAA since it forms more stable complexes and possess high ionic conductivities. Then, Li-salt containing PAA solutions are imidized by thermal process. The effect of interaction between host polymer and Li-salt is characterized by FT-IR (Fourier Transform Infrared spectroscopy and SEM (scanning electron micrsocopy. The conductivities of Li-salt and PEO containing PI composite membranes are in the range of 10–7–10–5 S•cm–1. The conductivity increases with incorporation of PEO. Thermogravimetric analysis results reveal that the PI/PEO/LiCF3SO3 composite polymer electrolyte membranes are thermally stable up to 500°C.

  7. Modelling of the diffusion of carbon dioxide in polyimide matrices by computer simulation

    OpenAIRE

    1992-01-01

    Computer aided molecular modelling is used to visualize the motion of CO2 gas molecules inside a polyimide polymer matrix. The polymers simulated are two 6FDA-bases polyimides, 6FDA-4PDA and 6FDA-44ODA. These polymers have also been synthesized in our laboratory, and thus the simulated properties could directly be compared with “real-world” data. The simulation experiments have been performed using the GROMOS1 package. The polymer boxes were created using the soft-core method, with short (11 ...

  8. A versatile multi-user polyimide surface micromachinning process for MEMS applications

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2015-04-01

    This paper reports a versatile multi-user micro-fabrication process for MEMS devices, the \\'Polyimide MEMS Multi-User Process\\' (PiMMPs). The reported process uses polyimide as the structural material and three separate metallization layers that can be interconnected depending on the desired application. This process enables for the first time the development of out-of-plane compliant mechanisms that can be designed using six different physical principles for actuation and sensing on a wafer from a single fabrication run. These principles are electrostatic motion, thermal bimorph actuation, capacitive sensing, magnetic sensing, thermocouple-based sensing and radio frequency transmission and reception. © 2015 IEEE.

  9. Feasibility of Kevlar 49/PMR-15 polyimide for high temperature applications

    Science.gov (United States)

    Hanson, M. P.

    1980-01-01

    Kevlar 49 aramid organic fiber reinforced PMR-15 polyimide laminates were characterized to determine the applicability of the material to high temperature aerospace structures. Kevlar 49/3501-6 epoxy laminates were fabricated and characterized for comparison with the Kevlar 49/PMR-15 polyimide material. Flexural strengths and moduli and interlaminar shear strengths were determined from 75 to 600 F for the PMR-15 and from 75 to 450 F for the Kevlar 49/3501-6 epoxy material. The study also included the effects of hydrothermal and long-term elevated temperature exposures on the flexural strengths and moduli and the interlaminar shear strengths.

  10. Synthesis and Characterization of Novel Polyimides Based on Pyridine-containing Diamine

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A new aromatic diamine monomer containing pyridine unit, 2,6-bis (4-aminophenoxy4′-benzoyl)pyridine(BABP), was synthesized in three steps, starting from 2,6-pyridinedicarboxyl chloride. A series of novel pyridine-containing polyimides were prepared via the polycondensation of BABP with various aromatic dianhydrides through poly(amic acid) precursors, and thermal or chemical imidization of the precursors. The polyimides exhibit desirable properties,e.g., good solubility in N-methyl-2-pyrrolidone and m-cresol, excellent thermal stability and ftlm-forming capability, as well as high inherent viscosity, indicating high molecular weight.

  11. Manufacturing processes for fabricating graphite/PMR 15 polyimide structural elements

    Science.gov (United States)

    Sheppard, C. H.; Hoggatt, J. T.; Symonds, W. A.

    1979-01-01

    Investigations were conducted to obtain commercially available graphite/PMR-15 polyimide prepreg, develop an autoclave manufacturing process, and demonstrate the process by manufacturing structural elements. Controls were established on polymer, prepreg, composite fabrication, and quality assurance, Successful material quality control and processes were demonstrated by fabricating major structural elements including flat laminates, hat sections, I beam sections, honeycomb sandwich structures, and molded graphite reinforced fittings. Successful fabrication of structural elements and simulated section of the space shuttle aft body flap shows that the graphite/PMR-15 polyimide system and the developed processes are ready for further evaluation in flight test hardware.

  12. SOLUBLE POLYIMIDES FROM A SEMI-ALIPHATIC DIAMINE CONTAINING ESTER, AMIDE AND ETHER GROUPS

    Institute of Scientific and Technical Information of China (English)

    Shahram Mehdipour-Ataei; Leila Akbarian-Feizi

    2011-01-01

    A diamine was synthesized by two successive reactions. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride yielded terephthaloyl bis(4-oxybenzoic) acid. Then reaction of this compound with 1,8-diamino-3,6dioxaoctane via Yamazaki method resulted in preparation of diamine named terephthalic acid bis(4-{2-[2-(2-amino ethoxy)ethoxy]ethyl carbamoyl}phenyl) ester. After fully characterization it was used to prepare new polyimides through polycondensation with different dianhydrides using trimethylchlorosilane. Characterization of polymers was achieved by common methods and their physical properties including inherent viscosity, thermal behavior, thermal stability, crystallinity and solubility were studied. Prepared polyimides showed improved solubility and good thermal stability.

  13. "Thermal Stabilization Effect" of Al2O3 nano-dopants improves the high-temperature dielectric performance of polyimide.

    Science.gov (United States)

    Yang, Yang; He, Jinliang; Wu, Guangning; Hu, Jun

    2015-11-24

    Insulation performance of the dielectrics under extreme conditions always attracts widespread attention in electrical and electronic field. How to improve the high-temperature dielectric properties of insulation materials is one of the key issues in insulation system design of electrical devices. This paper studies the temperature-dependent corona resistance of polyimide (PI)/Al2O3 nanocomposite films under high-frequency square-wave pulse conditions. Extended corona resistant lifetime under high-temperature conditions is experimentally observed in the 2 wt% nanocomposite samples. The "thermal stabilization effect" is proposed to explain this phenomenon which attributes to a new kind of trap band caused by nanoparticles. This effect brings about superior space charge characteristics and corona resistance under high temperature with certain nano-doping concentration. The proposed theory is experimentally demonstrated by space charge analysis and thermally stimulated current (TSC) tests. This discovered effect is of profound significance on improving high-temperature dielectric properties of nanocomposites towards various applications.

  14. Permittivity transition from highly positive to negative: Polyimide/carbon nanotube composite's dielectric behavior around percolation threshold

    Science.gov (United States)

    Sun, Yiyi; Wang, Junli; Qi, Shengli; Tian, Guofeng; Wu, Dezhen

    2015-07-01

    In this report, a series of composite films consisting of polyimide as the matrix and multi-wall carbon nanotubes as the filler (PI/MWCNTs) were prepared in a water-based method with the use of triethylamine. Their dielectric properties were tested under frequency of between 100 Hz and 10 MHz, and it was revealed that the permittivity value behaved interestingly around the percolation threshold (8.01% in volume). The water-based method ensured that fillers had high dispersibility in the matrix before percolation, which led to a relatively high dielectric constant (284.28). However, the overlapping caused by excess MWCNTs created pathways for electrons inside the matrix, turning the permittivity to negative. The former phenomenon was highly congruent with the percolation power law, while the latter could be explained by the Drude Model. AC conductivity was measured for more supportive information. Additionally, scanning electron microscopy and transmission electron microscopy were employed to record MWCNTs' microscopic distribution and morphology at the percolation threshold.

  15. Wideband vibrational electromagnetic energy harvesters with nonlinear polyimide springs based on rigid-flex printed circuit boards technology

    Science.gov (United States)

    Chiu, Yi; Hong, Hao-Chiao; Hsu, Wei-Hung

    2016-12-01

    A wideband vibrational electromagnetic energy harvester employing nonlinear spring effects is proposed and demonstrated. The harvesters were designed and fabricated by commercial rigid-flex printed circuit boards technology. Rigid FR-4 boards were used for mechanical support and coil winding, whereas flexible polyimide films were patterned for mechanical springs and mass platforms. Two sets of coils were patterned and fabricated in the harvester with an internal coil resistance of about 16 Ω each. Two rare-earth magnets were attached to the central platform as shuttle mass. The total dimension of the harvester was 20 × 20 × 4 mm3. In vibration tests, nonlinearity could be observed even at 0.1 grms vibration level due to the spring hardening effect. The frequency for peak induced voltage increased from 187 Hz at low vibration to 382 Hz at 5 grms vibration. The effective half-power bandwidth increased from 8 Hz at 0.1 grms to 32 Hz at 1 grms and 52 Hz at 5 grms due to the hysteresis in frequency response. For a matched load and 1 grms vibration at 250 Hz, the maximum output power was 160 nW, corresponding to a power density of 100 nW cm-3.

  16. Synthesis and Compatibility of Ionic Liquid Containing Rod-Coil Polyimide Gel Electrolytes with Lithium Metal Electrodes

    Science.gov (United States)

    Tigelaar, Dean M.; Palker, Allyson E.; Meador, Mary Ann B.; Bennett, William R.

    2008-01-01

    A highly cross-linked polyimide-polyethylene oxide copolymer has been synthesized that is capable of holding large volumes of liquid component, simultaneously maintaining good dimensional stability. An amine end capped oligomer was made that was imidized in solution, followed by reaction with a triisocyanate in the presence of desired additives at ambient temperature. Polymer films are able to hold over 4 times their weight in room temperature ionic liquid RTIL or carbonate solvent. Electrolytes were studied that contained varying amounts of RTIL, lithium trifluoromethanesulfonimide LiTFSi, and alumina nanoparticles. Electrochemical stability of these electrolytes with lithium metal electrodes was studied by galvanic cycling and impedance spectroscopy. Improved cycling stability and decreased interfacial resistance were observed when increasing amounts of RTIL and LiTFSi were added. The addition of small amounts of alumina further decreased interfacial resistance by nearly an order of magnitude. During the course of the study, cycling stability increased from less than 3 to greater than 1000 h at 60 C and 0.25 mA/cm2 current density.

  17. Morphology of latent and etched heavy ion tracks in radiation resistant polymers polyimide and poly(ethylene naphthalate)

    Science.gov (United States)

    Apel, P. Yu.; Blonskaya, I. V.; Oganessian, V. R.; Orelovitch, O. L.; Trautmann, C.

    2001-12-01

    The initial phase of chemical etching of ion tracks was studied in the radiation resistant polymers polyimide (PI) and poly(ethylene naphthalate) (PEN). Stacks of thin films were irradiated with Kr, Xe and Bi ions with energies of several MeV per nucleon. During the etching process, the evolution of the pore growth was monitored by conductometric measurements. Similar to earlier observations in other polymers, the etching process revealed the existence of two different radial damage zones, namely, a track core and a track halo. Compared to the virgin polymer, the etching rate in the core region is largely increased, whereas the halo exhibits a higher resistance to the chemical attack indicating radiation-induced cross-linking effects. Typical diameter of the central part of the latent track is measured for different stopping powers of the projectiles. The track to bulk etch ratio is found to reach 500-600 in PI and ˜10 000 in PEN. Due to this property, both materials seem to be suitable for producing micro- and even nanostructures with high aspect ratios.

  18. Synthesis and Compatibility of Ionic Liquid Containing Rod-Coil Polyimide Gel Electrolytes with Lithium Metal Electrodes

    Science.gov (United States)

    Tigelaar, Dean M.; Palker, Allyson E.; Meador, Mary Ann B.; Bennett, William R.

    2008-01-01

    A highly cross-linked polyimide-polyethylene oxide copolymer has been synthesized that is capable of holding large volumes of liquid component, simultaneously maintaining good dimensional stability. An amine end capped oligomer was made that was imidized in solution, followed by reaction with a triisocyanate in the presence of desired additives at ambient temperature. Polymer films are able to hold over 4 times their weight in room temperature ionic liquid RTIL or carbonate solvent. Electrolytes were studied that contained varying amounts of RTIL, lithium trifluoromethanesulfonimide LiTFSi, and alumina nanoparticles. Electrochemical stability of these electrolytes with lithium metal electrodes was studied by galvanic cycling and impedance spectroscopy. Improved cycling stability and decreased interfacial resistance were observed when increasing amounts of RTIL and LiTFSi were added. The addition of small amounts of alumina further decreased interfacial resistance by nearly an order of magnitude. During the course of the study, cycling stability increased from less than 3 to greater than 1000 h at 60 C and 0.25 mA/cm2 current density.

  19. High-performance carbon molecular sieve membranes for ethylene/ethane separation derived from an intrinsically microporous polyimide

    KAUST Repository

    Salinas, Octavio

    2015-11-18

    An intrinsically microporous polymer with hydroxyl functionalities, PIM-6FDA-OH, was used as a precursor for various types of carbon molecular sieve (CMS) membranes for ethylene/ethane separation. The pristine polyimide films were heated under controlled N2 atmosphere at different stages from 500 to 800 °C. All CMS samples carbonized above 600 °C surpassed the polymeric ethylene/ethane upper bound. Pure-gas selectivity reached 17.5 for the CMS carbonized at 800 °C with an ethylene permeability of about 10 Barrer at 2 bar and 35 °C, becoming the most selective CMS for ethylene/ethane separation reported to date. As expected, gravimetric sorption experiments showed that all CMS membranes had ethylene/ethane solubility selectivities close to one. The permselectivity increased with increasing pyrolysis temperature due to densification of the micropores in the CMS membranes, leading to enhanced diffusivity selectivity. Mixed-gas tests with a binary 50:50 v/v ethylene/ethane feed showed a decrease in selectivity from 14 to 8.3 as the total feed pressure was increased from 4 to 20 bar. The selectivity drop under mixed-gas conditions was attributed to non-ideal effects: (i) Competitive sorption that reduced the permeability of ethylene and (ii) dilation of the CMS that resulted in an increase in the ethane permeability.

  20. Coefficient of thermal expansion of stressed thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-dao; JIANG Shao-qing

    2006-01-01

    A new technique was proposed to determine the coefficient of thermal expansion (CTE) of thin films at low temperature. Different pre-stress could be applied and the elastic modulus of materials at different temperatures was measured with CTE simultaneously to eliminate the influence of mechanical deformation caused by the pre-stress. By using this technique,the CTEs of polyimide/silica nanocomposite films with different silica doping levels were experimentally studied at temperature from 77 K to 287 K,and some characteristics related to this new technique were discussed.