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Sample records for aged polymeric dielectric

  1. Dielectric films improve life of polymeric insulators

    Science.gov (United States)

    Hudis, M.; Wydeven, T.

    1975-01-01

    Degradation of polymeric insulators may be significantly reduced when polymer surfaces are coated with film having gradation of dielectric constants, larger where it is in contact with polymer and smaller at its exposed surface.

  2. Fullerene thin-film transistors fabricated on polymeric gate dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Puigdollers, J. [Micro and Nano Technology Group (MNT), Dept. Enginyeria Electronica, Universitat Politecnica Catalunya, C/ Jordi Girona 1-3, Modul C4, 08034-Barcelona (Spain)], E-mail: jpuigd@eel.upc.edu; Voz, C. [Micro and Nano Technology Group (MNT), Dept. Enginyeria Electronica, Universitat Politecnica Catalunya, C/ Jordi Girona 1-3, Modul C4, 08034-Barcelona (Spain); Cheylan, S. [ICFO - Mediterranean Technology Park, Avda del Canal Olimpic s/n, 08860-Castelldefels (Spain); Orpella, A.; Vetter, M.; Alcubilla, R. [Micro and Nano Technology Group (MNT), Dept. Enginyeria Electronica, Universitat Politecnica Catalunya, C/ Jordi Girona 1-3, Modul C4, 08034-Barcelona (Spain)

    2007-07-16

    Thin-film transistors with fullerene as n-type organic semiconductor have been fabricated. A polymeric gate dielectric, polymethyl methacrylate, has been used as an alternative to usual inorganic dielectrics. No significant differences in the microstructure of fullerene thin-films grown on polymethyl methacrylate were observed. Devices with either gold or aluminium top electrodes have been fabricated. Although the lower work-function of aluminium compared to gold should favour electron injection, similar field-effect mobilities in the range of 10{sup -2} cm{sup 2} V{sup -1} s{sup -1} were achieved in both cases. Actually, the output characteristics indicate that organic thin-film transistors behave more linearly with gold than with aluminium electrodes. These results confirm that not only energy barriers determine carrier injection at metal/organic interfaces, but also chemical interactions.

  3. Aging of Dielectric Properties below Tg

    DEFF Research Database (Denmark)

    Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil

    The dielectric loss at 1Hz in TPP is studied during a temperature step from one equilibrium state to another. In the applied cryostate the temperature can be equilibrated on a timescale of 1 second. The aging time dependence of the dielectric loss is studied below Tg applying temperature steps in...

  4. Quantitative property-structural relation modeling on polymeric dielectric materials

    Science.gov (United States)

    Wu, Ke

    Nowadays, polymeric materials have attracted more and more attention in dielectric applications. But searching for a material with desired properties is still largely based on trial and error. To facilitate the development of new polymeric materials, heuristic models built using the Quantitative Structure Property Relationships (QSPR) techniques can provide reliable "working solutions". In this thesis, the application of QSPR on polymeric materials is studied from two angles: descriptors and algorithms. A novel set of descriptors, called infinite chain descriptors (ICD), are developed to encode the chemical features of pure polymers. ICD is designed to eliminate the uncertainty of polymer conformations and inconsistency of molecular representation of polymers. Models for the dielectric constant, band gap, dielectric loss tangent and glass transition temperatures of organic polymers are built with high prediction accuracy. Two new algorithms, the physics-enlightened learning method (PELM) and multi-mechanism detection, are designed to deal with two typical challenges in material QSPR. PELM is a meta-algorithm that utilizes the classic physical theory as guidance to construct the candidate learning function. It shows better out-of-domain prediction accuracy compared to the classic machine learning algorithm (support vector machine). Multi-mechanism detection is built based on a cluster-weighted mixing model similar to a Gaussian mixture model. The idea is to separate the data into subsets where each subset can be modeled by a much simpler model. The case study on glass transition temperature shows that this method can provide better overall prediction accuracy even though less data is available for each subset model. In addition, the techniques developed in this work are also applied to polymer nanocomposites (PNC). PNC are new materials with outstanding dielectric properties. As a key factor in determining the dispersion state of nanoparticles in the polymer matrix

  5. Gated Seebeck Using Polymerized Ionic Liquid Gate Dielectrics

    Science.gov (United States)

    Thomas, Elayne; Popere, Bhooshan; Fang, Haiyu; Chabinyc, Michael; Segalman, Rachel

    Thermoelectric materials have the ability to convert a temperature gradient into usable electrical power via the Seebeck effect. This phenomenon is directly related to the material's Seebeck coefficient and electrical conductivity, which are in turn linked to its electron (or hole) mobility and carrier concentration. Organic semiconductors show promise for thermoelectric applications due to their flexibility and low-temperature manufacturing techniques; however, the role of ionized dopants on charge transport in these materials remains poorly understood. In this work, we use polymerized ionic liquids (PILs) as a gate dielectric in organic field-effect transistors to directly control the concentration of charges in the conducting channel. We report a method to tune the carrier concentration in the transistor channel via electrostatic gate modulation. We observe carrier concentration levels that are comparable to traditional doping methods with the added ability to precisely tune the concentration of charges induced. With this process, we aim to gather new information on the effect of ions on the performance of organic semiconductors in hopes of better understanding charge transport in conducting polymers on a molecular level.

  6. Raman microprobe analysis and ageing in dielectrics

    International Nuclear Information System (INIS)

    Subsurface voids in samples of electrically stressed low density polyethylene (LDPE) were analysed using confocal Raman microprobe spectroscopy (CRMS). An optical depth profiling technique was used to probe a void along the optic axis whilst a burst void was analysed at various lateral positions. Spectra from the voided samples showed signatures with similar features to those found in previous studies of electrical trees in polyethylene, including the presence of the D and G bands of disordered sp2 carbon. Results and spectra were then compared to the depth profiles and spectra from block and thin film samples of polyethylene and polystyrene which indicated that the established theory behind CRMS is oversimplified and that the detected signal is largely influenced by the optical properties of the material in question. Overall the study showed that despite some spatial resolution limitations of the technique, depth profiling is a useful tool in the analysis of aged polymers and dielectrics as it can show the variations in chemical composition with respect to position along the lateral and optic axis, a property especially relevant to electrical trees.

  7. Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization

    International Nuclear Information System (INIS)

    Commercial samples of Magnetite with size ranging from 25–30 nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed

  8. Effects of Polymeric Dielectric Morphology on Pentacene Morphology and Organic TFT Characteristics

    Directory of Open Access Journals (Sweden)

    Ye Rongbin

    2016-01-01

    Full Text Available In this paper, we report on the effects of the polymeric dielectric morphology on pentacene morphology and organic thin film transistor (TFT characteristics. The morphology and thickness of cyclo-olefin polymer (COP dielectric could be controlled by selecting a solvent. Higher the solvent’s boiling point is, thinner and smother COP films could be obtained. Using the solvent of trimethylcyclohexane, the spin-coated COP films of ca. 330 nm with the peak-to-valley of 7.35 nm and the roughness of root mean square of 0.58 nm were obtained, and pentacene TFT showed high mobility of 2.0 cm2V-1s-1, which originated from highly ordering of pentacene thin films deposited on the smoother and thinner COP films.

  9. Investigation of Plasma Polymerized Maleic Anhydride Film in a Middle Frequency Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    TANG Wenjie; CHEN Qiang; ZHANG Yuefei; GE Yuanjing

    2008-01-01

    Plasma polymerized maleic anhydride (MA) was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge (DBD). The film properties were characterized by water contact angle (WCA), Fourier transfer infrared (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as the power frequency, and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly (maleic anhydride) film is uniform and compact at an average deposition rate of 8 nm/min.

  10. Influence of dielectric constant of polymerization medium on processability and ammonia gas sensing properties of polyaniline

    Indian Academy of Sciences (India)

    Partha Pratim Sengupta; Pradip Kar; Basudam Adhikari

    2011-04-01

    Polyaniline (PANI) was synthesized by the oxidation of aniline hydrochloride in the presence of ammonium persulphate and hydrochloric acid. The polymerization reaction was carried out in several batches in different solvent media by changing the volume ratio of ,-dimethyl formamide (DMF) and water as binary solvent mixture. The dielectric constant of the polymerizationmedium for each batch reaction was determined by measuring the capacitance with change in frequency. The UV spectra of the synthesized polyaniline solutions helped us to optimize the ratio of the binary solvent to get sufficient polymer growth and processability. Thin film of processable polyaniline was then deposited on glass slides coated with polyvinyl alcohol (PVA) crosslinked with maleic anhydride (MA). FTIR and XRD studies of the coated film were also done. AFM studies further helped in the morphological study of the film deposited. Finally, conductivity and ammonia gas-sensing property of the polyaniline film were also studied.

  11. Effects of preparation methods on structure, ionic conductivity and dielectric relaxation of solid polymeric electrolytes

    International Nuclear Information System (INIS)

    The solid polymer electrolytes (SPEs) consisted of poly(ethylene oxide) (PEO) and lithium perchlorate (LiClO4) (PEO20–LiClO4 and PEO8–LiClO4 electrolytes of composition stoichiometric ratios EO:Li+ = 20:1 and 8:1) have been prepared by various blending methods. The simple solution casting, solution–cast hot pressed, dry blended melt pressed, high intensity ultrasonic assisted, microwave irradiated, and both the ultrasonicated and microwave irradiated solution–cast followed by their remelt with hot pressed methods have been used for preparation of the SPEs films. The complex formation between etheric oxygen (EO) of PEO and cation (Li+) of LiClO4 is confirmed by relative changes in amorphous phase of these electrolytes which is investigated by X-ray diffraction measurements. It is found that the amount of amorphous phase of these SPEs is strongly influenced by their preparation methods and the salt concentration. The complex dielectric function, ac electric conductivity, electric modulus and impedance spectra of the electrolytes are studied over the frequency range of 20 Hz to 1 MHz by dielectric relaxation spectroscopy at ambient temperature. The dc ionic conductivity of PEO8–LiClO4 electrolytes is found two to three orders of magnitude higher than that of the PEO20–LiClO4 electrolytes, which is significantly affected by their preparation methods. The cations coupled PEO chain segmental dynamics and its correlation with the ionic conductivity of these electrolytes has been explored by considering the values of relaxation times and dielectric relaxation strength. Results reveal that the ionic conductivity of PEO8–LiClO4 electrolytes can be tuned over two orders of magnitude by adopting different blending methods with a state-of-the-art engineering. - Highlights: • Solid polymeric electrolytes are synthesized with state-of-the-art novel techniques. • High intensity ultrasonication turned-up the electrolytes into an amorphous phase.

  12. Study of the aging processes in polyurethane adhesives using thermal treatment and differential calorimetric, dielectric, and mechanical techniques ; 1, identifying the aging processes ; 2, quantifying the aging effect

    CERN Document Server

    Althouse, L P

    1979-01-01

    Study of the aging processes in polyurethane adhesives using thermal treatment and differential calorimetric, dielectric, and mechanical techniques ; 1, identifying the aging processes ; 2, quantifying the aging effect

  13. Magnetic and dielectric properties of HoMnO{sub 3} nanoparticles synthesized by the polymerized complex method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xianguo, E-mail: liuxianguohugh@gmail.com [School of Materials Science and Engineering, Anhui University of technology, Ma' anshan, Anhui 243002 (China); Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Or, Siu Wing, E-mail: eeswor@polyu.edu.hk [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Sun, Yuping [Center for Engineering practice and Innovation Education, Anhui University of technology, Ma' anshan, Anhui 243002 (China); Jin, Chuangui; Lv, Yaohui [School of Materials Science and Engineering, Anhui University of technology, Ma' anshan, Anhui 243002 (China); Wu, Yuxi [Institute of Molecular Engineering and Applied Chemistry, Anhui University of Technology, Ma' anshan, Anhui 243002 (China)

    2013-06-15

    In this paper, we report on the magnetic and dielectric properties of HoMnO{sub 3} nanoparticles with different size synthesized by a polymerized complex method have been investigated. The HoMnO{sub 3} nanoparticles crystallized in hexagonal perovskite-type structure. The zero-field-cooled magnetic susceptibility curve of HoMnO{sub 3} nanoparticles with averaged size of 30 nm shows that complicated magnetic transitions occurred in a temperature range from 2 to 100 K, which was confirmed by magnetic hysteresis loops. With increasing the particle size, the antiferromagnetic (AFM) transition temperature increases from 56 to 77 K, due to the reduced surface-to-volume ratio. Moreover, with a decrease in particle size, the Mn-spin reorientation temperature (T{sub SR}) is enhanced from 44 to 48 K. - Highlights: • HoMnO{sub 3} nanoparticles have been synthesized by a polymerized complex method. • The magnetic properties of HoMnO{sub 3} nanoparticles have been investigated. • The dielectric properties of HoMnO{sub 3} nanoparticles have been investigated. • The antiferromagnetic transition temperature increases with the particle size.

  14. Stretchable Self-Healing Polymeric Dielectrics Cross-Linked Through Metal-Ligand Coordination.

    Science.gov (United States)

    Rao, Ying-Li; Chortos, Alex; Pfattner, Raphael; Lissel, Franziska; Chiu, Yu-Cheng; Feig, Vivian; Xu, Jie; Kurosawa, Tadanori; Gu, Xiaodan; Wang, Chao; He, Mingqian; Chung, Jong Won; Bao, Zhenan

    2016-05-11

    A self-healing dielectric elastomer is achieved by the incorporation of metal-ligand coordination as cross-linking sites in nonpolar polydimethylsiloxane (PDMS) polymers. The ligand is 2,2'-bipyridine-5,5'-dicarboxylic amide, while the metal salts investigated here are Fe(2+) and Zn(2+) with various counteranions. The kinetically labile coordination between Zn(2+) and bipyridine endows the polymer fast self-healing ability at ambient condition. When integrated into organic field-effect transistors (OFETs) as gate dielectrics, transistors with FeCl2 and ZnCl2 salts cross-linked PDMS exhibited increased dielectric constants compared to PDMS and demonstrated hysteresis-free transfer characteristics, owing to the low ion conductivity in PDMS and the strong columbic interaction between metal cations and the small Cl(-) anions which can prevent mobile anions drifting under gate bias. Fully stretchable transistors with FeCl2-PDMS dielectrics were fabricated and exhibited ideal transfer characteristics. The gate leakage current remained low even after 1000 cycles at 100% strain. The mechanical robustness and stable electrical performance proved its suitability for applications in stretchable electronics. On the other hand, transistors with gate dielectrics containing large-sized anions (BF4(-), ClO4(-), CF3SO3(-)) displayed prominent hysteresis due to mobile anions drifting under gate bias voltage. This work provides insights on future design of self-healing stretchable dielectric materials based on metal-ligand cross-linked polymers. PMID:27099162

  15. The detection of the early stages of ageing in an LDPE+graphite composite by comparison of dielectric responses induced by sinusoidal and triangular signals

    Directory of Open Access Journals (Sweden)

    I. Petronijevic

    2014-10-01

    Full Text Available This study describes the possibility of dielectric characterization of the initial stages of ageing in an low-density polyethylene (LDPE + graphite composite, which is not possible using the standard method of dielectric spectroscopy. It is shown that the differences between the delay angles, Δφ = φTRI – φSIN, obtained using triangular and sinusoidal excitations on the composite samples, shows a maximum, and at the same time the position of this maximum shows more sensitivity to changes in the electrical properties of the material caused by ageing than other dielectric parameters. In order to clarify the applied methodology, a comparative analysis of the dielectric properties of other polymers poly(vinyl chloride (PVC and poly(vinyl alcohol (PVA and a conductive polymer composite (LDPE + carbon black with respect to the application of sinusoidal and triangular electrical signals was carried out. Based on the presented results, we believe that the position of the peak in the frequency spectra of the difference between the delay angles obtained by using triangular and sinusoidal signals may be a suitable parameter for the dielectric characterization of polymeric materials.

  16. Electrical Breakdown and Mechanical Ageing in Dielectric Elastomers

    DEFF Research Database (Denmark)

    Zakaria, Shamsul Bin

    Dielectric elastomers (DE) are used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. For many applications, one of the major factors that limits the DE performance is premature electrical breakdown. There are many approaches that have been...

  17. Chain Dynamics in Solid Polymers and Polymerizing Systems as Revealed by Broadband Dielectric Spectroscopy

    Science.gov (United States)

    Williams, Graham

    2008-08-01

    A number of techniques are used to study the chain-dynamics of solid polymers, including those of dielectric relaxation [1-4], dynamic mechanical thermal analysis (DMTA) [1, 5], multinuclear NMR relaxations [6], quasi-elastic dynamic light scattering [7] and neutron scattering [8] (QELS & QENS) and transient fluorescence depolarization (TFD) [9]. Each technique has its own particular probe of the dynamics in a material. e.g. dielectric relaxation gives information on the angular motions of molecular chain-dipoles (for dipole relaxation) and the translational motions of ions (for f-dependent electrical conduction); NMR relaxations relate to the angular motions of chemical bonds; QELS relates to fluctuations in local refractive index; QENS to the time-dependent van Hove correlation function (suitably-defined) for proton-containing groups; TFD to the angular motions of fluorescent groups in a chain. Due to its relevance to practical applications of materials, DMTA is pre-eminent among the many physical techniques applied to solid polymers, but interpretations of behaviour in terms of molecular properties remain difficult since the direct link between an applied macroscopic stress and the molecular response of polymer chains in a bulk material remains an unsolved problem. Of the above techniques, Broadband Dielectric Spectroscopy (BDS) offers several advantages. (a) Materials may be studied in the frequency range 10-6 to 1010 Hz, over wide ranges of temperature and applied pressure, using commercially-available instrumentation. (b) Since the electrical capacitance of a film is inversely proportional its thickness, free-standing and supported films may be studied down to nm-thicknesses, giving e.g. information on the behaviour of the dynamic Tg as sample thickness approaches molecular dimensions. (c) Theoretical interpretations of dielectric relaxation and a.c. conduction are well-established in terms of Fourier transforms of molecular time correlation functions (TCFs

  18. Correlation between mechanical and dielectric properties of Alfa/Wool/Polymeric hybrid fibres reinforced polyester composites

    International Nuclear Information System (INIS)

    Dielectric measurements and tensile testing of polyester/natural fibres (Alfa/wool) and thermo binder fibres (Pe/Pet) composites were investigated in order to study the adhesion of the fibres in the polyester matrix. Two composites #1 and #2 having 17:1:2 and 17:2:1 as a relative fraction of alfa/wool and thermo binder (Pe/Pet), respectively, have been characterized in this study. The obtained results revealed that the fibres adhesion in the matrix was better in the composite #1 than in the composite #2. Indeed, the analysis of the interfacial or Maxwell-Wagner-Sillars (MWS) polarization intensity, using the Havriliak–Negami model, has shown a lower intensity and the tensile testing exhibited a higher Young modulus in the composite #1. So the thermo binder fibres improve this adhesion

  19. Dynamics of asymmetric non-polymeric binary glass formers—A nuclear magnetic resonance and dielectric spectroscopy study

    International Nuclear Information System (INIS)

    We study a dynamically asymmetric binary glass former with the low-Tg component m-tri-cresyl phosphate (m-TCP: Tg = 206 K) and a spirobichroman derivative as a non-polymeric high-Tg component (Tg = 382 K) by means of 1H nuclear magnetic resonance (NMR), 31P NMR, and dielectric spectroscopy which allow component-selectively probing the dynamics. The entire concentration range is covered, and two main relaxation processes with two Tg are identified, Tg1 and Tg2. The slower one is attributed to the high-Tg component (α1-process), and the faster one is related to the m-TCP molecules (α2-process). Yet, there are indications that a small fraction of m-TCP is associated also with the α1-process. While the α1-relaxation only weakly broadens upon adding m-TCP, the α2-relaxation becomes extremely stretched leading to quasi-logarithmic correlation functions at low m-TCP concentrations—as probed by 31P NMR stimulated echo experiments. Frequency-temperature superposition does not apply for the α2-process and it reflects an isotropic, liquid-like motion which is observed even below Tg1, i.e., in the matrix of the arrested high-Tg molecules. As proven by 2D 31P NMR, the corresponding dynamic heterogeneities are of transient nature, i.e., exchange occurs within the distribution G(lnτα2). At Tg1 a crossover is found for the temperature dependence of (mean) τα2(T) from non-Arrhenius above to Arrhenius below Tg1 which is attributed to intrinsic confinement effects. This “fragile-to-strong” transition also leads to a re-decrease of Tg2(cm−TCP) at low concentration cm−TCP, i.e., a maximum is observed in Tg2(cm−TCP) while Tg1(cm−TCP) displays the well-known plasticizer effect. Although only non-polymeric components are involved, we re-discover essentially all features previously reported for polymer-plasticizer systems

  20. Dynamics of asymmetric non-polymeric binary glass formers—A nuclear magnetic resonance and dielectric spectroscopy study

    Science.gov (United States)

    Pötzschner, B.; Mohamed, F.; Lichtinger, A.; Bock, D.; Rössler, E. A.

    2015-10-01

    We study a dynamically asymmetric binary glass former with the low-Tg component m-tri-cresyl phosphate (m-TCP: Tg = 206 K) and a spirobichroman derivative as a non-polymeric high-Tg component (Tg = 382 K) by means of 1H nuclear magnetic resonance (NMR), 31P NMR, and dielectric spectroscopy which allow component-selectively probing the dynamics. The entire concentration range is covered, and two main relaxation processes with two Tg are identified, Tg1 and Tg2. The slower one is attributed to the high-Tg component (α1-process), and the faster one is related to the m-TCP molecules (α2-process). Yet, there are indications that a small fraction of m-TCP is associated also with the α1-process. While the α1-relaxation only weakly broadens upon adding m-TCP, the α2-relaxation becomes extremely stretched leading to quasi-logarithmic correlation functions at low m-TCP concentrations—as probed by 31P NMR stimulated echo experiments. Frequency-temperature superposition does not apply for the α2-process and it reflects an isotropic, liquid-like motion which is observed even below Tg1, i.e., in the matrix of the arrested high-Tg molecules. As proven by 2D 31P NMR, the corresponding dynamic heterogeneities are of transient nature, i.e., exchange occurs within the distribution G(lnτα2). At Tg1 a crossover is found for the temperature dependence of (mean) τα2(T) from non-Arrhenius above to Arrhenius below Tg1 which is attributed to intrinsic confinement effects. This "fragile-to-strong" transition also leads to a re-decrease of Tg2(cm-TCP) at low concentration cm-TCP, i.e., a maximum is observed in Tg2(cm-TCP) while Tg1(cm-TCP) displays the well-known plasticizer effect. Although only non-polymeric components are involved, we re-discover essentially all features previously reported for polymer-plasticizer systems.

  1. Dynamics of asymmetric non-polymeric binary glass formers—A nuclear magnetic resonance and dielectric spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Pötzschner, B.; Mohamed, F.; Lichtinger, A.; Bock, D.; Rössler, E. A., E-mail: ernst.roessler@uni-bayreuth.de [Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth (Germany)

    2015-10-21

    We study a dynamically asymmetric binary glass former with the low-T{sub g} component m-tri-cresyl phosphate (m-TCP: T{sub g} = 206 K) and a spirobichroman derivative as a non-polymeric high-T{sub g} component (T{sub g} = 382 K) by means of {sup 1}H nuclear magnetic resonance (NMR), {sup 31}P NMR, and dielectric spectroscopy which allow component-selectively probing the dynamics. The entire concentration range is covered, and two main relaxation processes with two T{sub g} are identified, T{sub g1} and T{sub g2}. The slower one is attributed to the high-T{sub g} component (α{sub 1}-process), and the faster one is related to the m-TCP molecules (α{sub 2}-process). Yet, there are indications that a small fraction of m-TCP is associated also with the α{sub 1}-process. While the α{sub 1}-relaxation only weakly broadens upon adding m-TCP, the α{sub 2}-relaxation becomes extremely stretched leading to quasi-logarithmic correlation functions at low m-TCP concentrations—as probed by {sup 31}P NMR stimulated echo experiments. Frequency-temperature superposition does not apply for the α{sub 2}-process and it reflects an isotropic, liquid-like motion which is observed even below T{sub g1}, i.e., in the matrix of the arrested high-T{sub g} molecules. As proven by 2D {sup 31}P NMR, the corresponding dynamic heterogeneities are of transient nature, i.e., exchange occurs within the distribution G(lnτ{sub α2}). At T{sub g1} a crossover is found for the temperature dependence of (mean) τ{sub α2}(T) from non-Arrhenius above to Arrhenius below T{sub g1} which is attributed to intrinsic confinement effects. This “fragile-to-strong” transition also leads to a re-decrease of T{sub g2}(c{sub m−TCP}) at low concentration c{sub m−TCP}, i.e., a maximum is observed in T{sub g2}(c{sub m−TCP}) while T{sub g1}(c{sub m−TCP}) displays the well-known plasticizer effect. Although only non-polymeric components are involved, we re-discover essentially all features previously

  2. Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Carlos A.; Coser, E. [Laboratorio de Materiais Polimericos, Departamento de Engenharia de Materiais, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)], e-mail: ferreira.carlos@ufrgs.br; Angelini, Joceli M.G. [Departamento de Materiais Eletricos, CPqD, Campinas, SP (Brazil); Rossi, Jose A.D. [Materiais Alta Tensao, CPqD, Campinas, SP (Brazil); Martinez, Manuel L.B. [Departamento de Engenharia Eletrica, UNIFEI, Itajuba, MG (Brazil)

    2011-07-01

    A study was conducted to evaluate new and laboratory-aged samples of surge arresters and anchorage polymeric insulators, for 12 and 24 kV networks, which are used by the Rio Grande Energia (RGE). Power utility polymeric compounds were analyzed by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG), Dynamic-Mechanic Analysis (DMA), Fourier Transformed Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM) to verify changes in the insulator properties due to degradation occurred during the experiments. The analyses were carried out before and after 6 months of aging in laboratory devices (weather meter, 120 deg C, salt spray, immersion in water). After the aging experiments, high-voltage electrical tests were also conducted: a radio interference voltage test and, simultaneously, the total and the internal leakage currents were measured to verify the surface degradation of the polymeric material used in the housing. The impulse current test was applied with current values close to 5, 10 and 30 k A, in order to force an internal degradation. Results showed that only surface degradation is detected at the polymer. The main properties of the parts were not affected by the aging. It confirms that polymer insulator and surge arrester are appropriate for use in electricity distribution networks. (author)

  3. Effect of artificial aging on polymeric surge arresters and polymer insulators for electricity distribution networks

    Directory of Open Access Journals (Sweden)

    Carlos A. Ferreira

    2011-01-01

    Full Text Available A study was conducted to evaluate new and laboratory-aged samples of surge arresters and anchorage polymeric insulators, for 12 and 24 kV networks, which are used by the Rio Grande Energia (RGE. Power Utility Polymeric compounds were analyzed by Differential Scanning Calorimetry (DSC, Thermogravimetric Analysis (TG, Dynamic-Mechanic Analysis (DMA, Fourier Transformed Infrared Spectroscopy (FTIR and Scanning Electronic Microscopy (SEM to verify changes in the insulator properties due to degradation occurred during the experiments. The analyses were carried out before and after 6 months of aging in laboratory devices (weatherometer, 120 °C, salt spray, immersion in water. After the aging experiments, high-voltage electrical tests were also conducted: a radio interference voltage test and, simultaneously, the total and the internal leakage currents were measured to verify the surface degradation of the polymeric material used in the housing. The impulse current test was applied with current values close to 5, 10 and 30 kA, in order to force an internal degradation. Results showed that only surface degradation is detected at the polymer. The main properties of the parts were not affected by the aging. It confirms that polymer insulator and surge arrestor are appropriate for use in electricity distribution networks.

  4. Polymeric membranes for CO2 separation: effect of aging, humidity and facilitated transport

    OpenAIRE

    Ansaloni, Luca

    2014-01-01

    Polymeric membranes represent a promising technology for gas separation processes, thanks to low costs, reduced energy consumption and limited waste production. The present thesis aims at studying the transport properties of two membrane materials, suitable for CO2 purification applications. In the first part, a polyimide, Matrimid 5218, has been throughout investigated, with particular reference to the effect of thermal treatment, aging and the presence of water vapor in the gas transport pr...

  5. On the Use of Accelerated Aging Methods for Screening High Temperature Polymeric Composite Materials

    Science.gov (United States)

    Gates, Thomas S.; Grayson, Michael A.

    1999-01-01

    A rational approach to the problem of accelerated testing of high temperature polymeric composites is discussed. The methods provided are considered tools useful in the screening of new materials systems for long-term application to extreme environments that include elevated temperature, moisture, oxygen, and mechanical load. The need for reproducible mechanisms, indicator properties, and real-time data are outlined as well as the methodologies for specific aging mechanisms.

  6. Monitoring migration and transformation of nanomaterials in polymeric composites during accelerated aging

    International Nuclear Information System (INIS)

    The incorporation of small amounts of nanoadditives in polymeric compounds can introduce new mechanical, physical, electrical, magnetic, thermal and/or optical properties. The properties of these advanced materials have enabled new applications in several industrial sectors (electronics, automotive, textile...). In particular, for the nanomaterials (NM) described in this work, multi-walled carbon nanotubes (MWCNT) and silicon dioxide nanoparticles (SiO2 NP), the following properties have been described: MWCNT act as nucleating agents in thermoplastics, and change viscosity, affecting dispersion, orientation, and therefore mechanical, thermal, and electrical properties; and SiO2 NP act as flame retardant and display improved electrical and mechanical properties. The work described here is focused on the evaluation of the migration and transformation of NM included in polymer nanocomposites (NC) during accelerated climatic ageing. To this aim, we generated polyamide 6 (PA6) NC with different degree of compatibility between the NM and the polymeric matrix. These NC were submitted to accelerated aging conditions to simulate outdoor conditions (simulation of the use phase of the polymeric NC). The NC contain as nanofillers MWCNT and SiO2 NP with different surface properties to influence the compatibility with the polymeric matrix. The generated NC were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) with Energy-dispersive X-ray spectroscopy (EDX), thermogravimetry (TGA) and differential scanning calorimetry (DSC) before and after the aging process, to monitor the compatibility of the NM with the matrix: dispersion within the matrix, migration during aging, and modification of the polymer properties. The dispersion of SiO2 NP in the NC depended on their compatibility with the matrix. However, independently of their compatibility with the matrix, SiO2 NP were aggregated at the end of the accelerated aging process. In addition

  7. Monitoring migration and transformation of nanomaterials in polymeric composites during accelerated aging

    Science.gov (United States)

    Vilar, G.; Fernández-Rosas, E.; Puntes, V.; Jamier, V.; Aubouy, L.; Vázquez-Campos, S.

    2013-04-01

    The incorporation of small amounts of nanoadditives in polymeric compounds can introduce new mechanical, physical, electrical, magnetic, thermal and/or optical properties. The properties of these advanced materials have enabled new applications in several industrial sectors (electronics, automotive, textile...). In particular, for the nanomaterials (NM) described in this work, multi-walled carbon nanotubes (MWCNT) and silicon dioxide nanoparticles (SiO2 NP), the following properties have been described: MWCNT act as nucleating agents in thermoplastics, and change viscosity, affecting dispersion, orientation, and therefore mechanical, thermal, and electrical properties; and SiO2 NP act as flame retardant and display improved electrical and mechanical properties. The work described here is focused on the evaluation of the migration and transformation of NM included in polymer nanocomposites (NC) during accelerated climatic ageing. To this aim, we generated polyamide 6 (PA6) NC with different degree of compatibility between the NM and the polymeric matrix. These NC were submitted to accelerated aging conditions to simulate outdoor conditions (simulation of the use phase of the polymeric NC). The NC contain as nanofillers MWCNT and SiO2 NP with different surface properties to influence the compatibility with the polymeric matrix. The generated NC were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) with Energy-dispersive X-ray spectroscopy (EDX), thermogravimetry (TGA) and differential scanning calorimetry (DSC) before and after the aging process, to monitor the compatibility of the NM with the matrix: dispersion within the matrix, migration during aging, and modification of the polymer properties. The dispersion of SiO2 NP in the NC depended on their compatibility with the matrix. However, independently of their compatibility with the matrix, SiO2 NP were aggregated at the end of the accelerated aging process. In addition

  8. Flavonoids as Natural Stabilizers and Color Indicators of Ageing for Polymeric Materials

    Directory of Open Access Journals (Sweden)

    Anna Masek

    2015-06-01

    Full Text Available Few changes have occurred in the use of various stabilizers over recent years. In the current literature, phosphate derivatives are used as anti-ageing additives in polymers, and the most popular of these are sterically hindering cyclic amines. However, most of these compounds are carcinogenic. Synthetic phenols have been increasingly used as antioxidants in food and in polymers. Ecological standards encourage the elimination of harmful additives in polymeric products that come in contact with food or with the human body. This article presents application of flavonoid (silymarin/flavonoligand for polymer stabilization and use of natural phytocompounds such as color indicators of polymers ageing time. In this research, I propose two ways of application: traditional, during processing; and the new one, by using impregnation method. Based on the change of deformation energy (ageing coefficient K, FTIR, oxidative induction time (OIT evaluated by differential scanning calorimetry (OIT, thermogravimetry analysis (TG, spectrophotometric color measurements in terms of CIE-Lab color space values, I confirmed the high antioxidant activity of flavonoids in EPM. They provide coloration of the polymeric materials that changes cyclically as a function of aging time. Additionally, the use of phytocompounds in polymers provides similar stabilizing effect to those of synthetic antioxidants.

  9. Accelerated Aging Effect on Epoxy-polysiloxane Polymeric Insulator Material with Rice Husk Ash Filler

    Directory of Open Access Journals (Sweden)

    Rochmadi .

    2012-08-01

    Full Text Available The performances of outdoor polymeric insulators are influenced by environmental conditions. This paper presents the effect of artificial tropical climate on the hydrophobicity, equivalent salt deposit density (ESDD, surface leakage current, flashover voltage, and surface degradation on epoxy-polysiloxane polymeric insulator materials with rice husk ash (RHA. Test samples are made at room temperature vulcanized (RTV of various composition of epoxy-polysiloxane with rice husk ash as filler. The aging was carried out in test chamber at temperature from 50oC to 62oC, relative humidity of 60% to 80%, and ultraviolet (UV  radiation 21.28 w/cm2 in daylight conditions for 96 hours. The experiment results showed that the flashover voltage fluctuates from 34.13 kV up to 40.92 kV and tends to decrease on each variation of material composition. The surface leakage current fluctuates and tends to increase. Test samples with higher filler content result greater hydrophobicity, smaller equivalent salt deposit density, and smaller critical leakage current, which caused the increase of the flashover voltage. Insulator material (RTVEP3 showed the best performance in tropical climate environment. Artificial tropical aging for short duration gives less effect to the surface degradation of epoxy-polysiloxane insulator material.

  10. Effect of titanium oxide–polystyrene nanocomposite dielectrics on morphology and thin film transistor performance for organic and polymeric semiconductors

    International Nuclear Information System (INIS)

    Previous studies have shown that organic thin film transistors with pentacene deposited on gate dielectrics composed of a blend of high K titanium oxide–polystyrene core–shell nanocomposite (TiO2–PS) with polystyrene (PS) perform with an order of magnitude increase in saturation mobility for TiO2–PS (K = 8) as compared to PS devices (K = 2.5). The current study finds that this performance enhancement can be translated to alternative small single crystal organics such as α-sexithiophene (α-6T) (enhancement factor for field effect mobility ranging from 30-100× higher on TiO2–PS/PS blended dielectrics as compared to homogenous PS dielectrics). Interestingly however, in the case of semicrystalline polymers such as (poly-3-hexylthiophene) P3HT, this dramatic enhancement is not observed, possibly due to the difference in processing conditions used to fabricate these devices (film transfer as opposed to thermal evaporation). The morphology for α-sexithiophene (α-6T) grown by thermal evaporation on TiO2–PS/PS blended dielectrics parallels that observed in pentacene devices. Smaller grain size is observed for films grown on dielectrics with higher TiO2–PS content. In the case of poly(3-hexylthiophene) (P3HT) devices, constructed via film transfer, morphological differences exist for the P3HT on different substrates, as discerned by atomic force microscopy studies. However, these devices only exhibit a modest (2×) increase in mobility with increasing TiO2–PS content in the films. After annealing of the transferred P3HT thin film transistor (TFT) devices, no appreciable enhancement in mobility is observed across the different blended dielectrics. Overall the results support the hypothesis that nucleation rate is responsible for changes in film morphology and device performance in thermally evaporated small molecule crystalline organic semiconductor TFTs. The increased nucleation rate produces organic polycrystalline films with small grain size which are

  11. Determination of Relationship between Dielectric Properties, Compressive Strength, and Age of Concrete with Rice Husk Ash Using Planar Coaxial Probe

    Directory of Open Access Journals (Sweden)

    Piladaeng Nawarat

    2016-02-01

    Full Text Available This paper deals with an investigation of the dielectric properties of concretes that includes rice husk ash using a planar coaxial probe. The planar coaxial probe has a planar structure with a microstrip and coaxial features. The measurement was performed over the frequency range of 0.5-3.5 GHz, and concrete specimens with different percentages of rice husk ash were tested. The results indicated that the dielectric constant of the concretes was inversely proportional to the frequency, while the conductivity was proportional to the frequency. The dielectric constant decreased with the increasing age of the concrete at the frequency of 1 GHz. The conductivity of the concrete decreased with the increasing age of the concrete at the frequency of 3.2 GHz. In addition, the dielectric constant and the conductivity decreased when the compressive strength increased. It was also shown that the obtained dielectric properties of the concrete could be used to investigate the relationship between the compressive strength and age of the concrete. Moreover, there is an opportunity to apply the proposed probe to determine the dielectric properties of other materials.

  12. Determination of Relationship between Dielectric Properties, Compressive Strength, and Age of Concrete with Rice Husk Ash Using Planar Coaxial Probe

    Science.gov (United States)

    Piladaeng, Nawarat; Angkawisittpan, Niwat; Homwuttiwong, Sahalaph

    2016-02-01

    This paper deals with an investigation of the dielectric properties of concretes that includes rice husk ash using a planar coaxial probe. The planar coaxial probe has a planar structure with a microstrip and coaxial features. The measurement was performed over the frequency range of 0.5-3.5 GHz, and concrete specimens with different percentages of rice husk ash were tested. The results indicated that the dielectric constant of the concretes was inversely proportional to the frequency, while the conductivity was proportional to the frequency. The dielectric constant decreased with the increasing age of the concrete at the frequency of 1 GHz. The conductivity of the concrete decreased with the increasing age of the concrete at the frequency of 3.2 GHz. In addition, the dielectric constant and the conductivity decreased when the compressive strength increased. It was also shown that the obtained dielectric properties of the concrete could be used to investigate the relationship between the compressive strength and age of the concrete. Moreover, there is an opportunity to apply the proposed probe to determine the dielectric properties of other materials.

  13. Surface modification of thermoplastic poly(vinyl alcohol)/saponite nanocomposites via surface-initiated atom transfer radical polymerization enhanced by air dielectric discharges barrier plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhen Weijun [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065 (China); Lu Canhui, E-mail: canhuilu@scu.edu.cn [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065 (China)

    2012-07-01

    To improve the water resistance of thermoplastic poly(vinyl alcohol)/saponite nanocomposites (TPVA), a simple two-step method was developed for the covalent immobilization of atom transfer radical polymerization (ATRP) initiators on the TPVA surfaces enhanced by air dielectric barrier discharges (DBD) plasma treatment, and hydrophobic poly(methyl methacrylate) (PMMA) brushes were then grafted onto the surface of TPVA via surface-initiated atom transfer radical polymerization (SI-ATRP). The chemical composition, morphology and hydrophobicity of the modified TPVA surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The water resistance of the surface-functionalized PMMA was evaluated by the contact angle and water adsorption method. It was shown that air DBD plasma treatment activated the TPVA surface and accelerated the immobilization of ATRP initiator on the TPVA surface. Compared with TPVA control, TPVA modified by SI-ATRP can be grafted well-defined and covalently tethered network PMMA brushes onto the surface and the hydrophobicity of TPVA were significantly enhanced.

  14. Cable aging and condition monitoring of radiation resistant nano-dielectrics in advanced reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Duckworth, Robert C [ORNL; Aytug, Tolga [ORNL; Paranthaman, Mariappan Parans [ORNL; Kidder, Michelle [ORNL; Polyzos, Georgios [ORNL; Leonard, Keith J [ORNL

    2015-01-01

    Cross-linked polyethylene (XLPE) nanocomposites have been developed in an effort to improve cable insulation lifetime to serve in both instrument cables and auxiliary power systems in advanced reactor applications as well as to provide an alternative for new or retro-fit cable insulation installations. Nano-dielectrics composed of different weight percentages of MgO & SiO2 have been subjected to radiation at accumulated doses approaching 20 MRad and thermal aging temperatures exceeding 100 C. Depending on the composition, the performance of the nanodielectric insulation was influenced, both positively and negatively, when quantified with respect to its electrical and mechanical properties. For virgin unradiated or thermally aged samples, XLPE nanocomposites with 1wt.% SiO2 showed improvement in breakdown strength and reduction in its dissipation factor when compared to pure undoped XLPE, while XLPE 3wt.% SiO2 resulted in lower breakdown strength. When aged in air at 120 C, retention of electrical breakdown strength and dissipation factor was observed for XLPE 3wt.% MgO nanocomposites. Irrespective of the nanoparticle species, XLPE nanocomposites that were gamma irradiated up to the accumulated dose of 18 MRad showed a significant drop in breakdown strength especially for particle concentrations greater than 3 wt.%. Additional attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy measurements suggest changes in the structure of the XLPE SiO2 nanocomposites associated with the interaction of silicon and oxygen. Discussion on the relevance of property changes with respect to cable aging and condition monitoring is presented.

  15. Dynamics of polymerization in polyacrylamide gel (PAG) dosimeters: (I) ageing and long-term stability

    International Nuclear Information System (INIS)

    Few quantitative data are available on the kinetics of polymerization reactions in polymer gel (PAG) dosimeters and their long-term stability. Post-irradiation polymerization reactions have been found to continue for several weeks, posing questions regarding dosimeter stability and its achievement. In this paper we report an investigation of polymerization kinetics in PAG dosimeters and the effect of diffusing oxygen into the dosimeter, post-irradiation, as a potential method of inhibiting further polymerization and stabilizing the dose distribution. Results show continuous post-irradiation changes in transverse relaxation rate R2 with time over the five week study period and that a steady-state may not be reached for a period of months. An assessment is made of the appropriate time to image the dosimeter which shows that after three to four days the polymerization change is slow compared with imaging time. The implications of the time delay between irradiation and imaging are discussed in terms of the resultant sensitivity of the dosimeter and accuracy of the dose measured. In pairs of dosimeters, one sealed the other open to air, oxygen diffusing into the dosimeter arrests polymerization. However, the diffusion rate is too slow to make this method practicable. The slow diffusion means that while in regions near the air/gel interface polymerization is quickly arrested, in deeper regions it may continue for many hours, causing artefacts in the dose distribution. In the companion paper to this from a collaborating team, a study focusing on modelling oxygen diffusion in dosimeter gel will be presented. (author)

  16. Dyes with high dielectric constants

    OpenAIRE

    Langhals, Heinz

    1988-01-01

    The dielectric constants of perylene dyes, perylene-3,4: 9,10-tetracarboxylic bisimides, are reported. With aromatic substituents, dielectric constants up to 110 are obtained. With polymeric dyes, the dielectric constants rise to 260. Mechanisms and applications are discussed.

  17. Ageing effects on polymeric track detectors: studies of etched tracks at nano size scale using atomic force microscope

    International Nuclear Information System (INIS)

    Among several different techniques to analyze material surface, the use of Atomic Force Microscope is one of the finest method. As we know, the sensitivity to detect energetic ions is extremely affected during the storage time and conditions of the polymeric material used as a nuclear track detector. On the basis of the surface analysis of several track detector materials, we examined the detection sensitivity of these detectors exposed to alpha particles. The preliminary results revealed that the ageing effect on its sensitivity is very strong, that need to be considered on the routine applications or research experiments. The results are consistent with the experimental data in the literature. (Author)

  18. Dielectric materials for electrical engineering

    CERN Document Server

    Martinez-Vega, Juan

    2013-01-01

    Part 1 is particularly concerned with physical properties, electrical ageing and modeling with topics such as the physics of charged dielectric materials, conduction mechanisms, dielectric relaxation, space charge, electric ageing and life end models and dielectric experimental characterization. Part 2 concerns some applications specific to dielectric materials: insulating oils for transformers, electrorheological fluids, electrolytic capacitors, ionic membranes, photovoltaic conversion, dielectric thermal control coatings for geostationary satellites, plastics recycling and piezoelectric poly

  19. Dielectric and mechanical properties of ethylene-propylene rubber subjected to complex aging due to radiation and heat

    International Nuclear Information System (INIS)

    The radiation damage of polymers is largely controlled by dose rate, oxygen concentration and heat. The Takasaki Radiation Chemistry Research Establishment of Japan Atomic Energy Research Institute has determined oxygen consumption and the quantity of gas generated, analyzed the oxides produced in polymers, and obtained the secondary structure change analyzed by the measured results for gel fraction and swelling ratio, and the change of mechanical properties by tensile test for polyethylene and ethylene-propylene rubber (EPR), when γ-ray was applied in oxygen, and has clarified that oxidation plays an important role for the radiation damage of polymers. In this study, it was attempted to determine the relation of aging conditions to the aging behaviour through the difference in the mechanical properties and that in the molecular movement when polymers were subjected to thermal aging only, to the sequential complex aging of heating after irradiation, and to the simultaneous complex aging of heat and irradiation. Simply compounded, chemically cross-linked EPR was selected as the sample, and tensile test and the measurement of dynamic viscoelasticity and dielectric properties were performed, using the unirradiated samples, the samples irradiated by 100 Mrad under the condition of 500 krad/h with a 60Co source, in 5 kg/cm2 oxygen, and at room temperature, and the samples irradiated by 10, 20 and 25 Mrad under the condition of 5 krad/h, in air and at 120 deg C. Consideration on three stages of the thermal aging for the unirradiated and irradiated samples and on the thermal aging under irradiation is described. (Wakatsuki, Y.)

  20. Scattering and Physical Aging in High-Free-Volume Polymeric Glasses

    Science.gov (United States)

    McDermott, Amanda G.; Budd, Peter M.; McKeown, Neil B.; Colina, Coray M.; Runt, James

    2013-03-01

    Polymers of intrinsic microporosity (PIMs) form glassy, rigid membranes featuring a large concentration of pores smaller than 1 nm, large internal surface area, and high gas permeability and selectivity. Porosity in these materials--equivalent to free volume--arises from an unusual chain structure combining rigid segments with sites of contortion. Like other glasses, PIMs are subject to physical aging, which reduces the permeability of films over time. Although it is possible to derive useful information such as surface areas and pore sizes from the scattering patterns of many porous materials, scattering from PIMs includes some unusual features. A robust interpretation of these features is presented with support from molecular dynamics simulations. The sensitivity of PIM SAXS/WAXS patterns to time, temperature and film thickness is shown to be qualitatively consistent with physical aging. Models for extracting quantitative information about changes in the sizes and volume fraction of pores are also discussed. Supported by NSF

  1. Dielectric Spectroscopy of Bisphenol A Epoxy Resin Aged in Wet and Dry Conditions

    OpenAIRE

    Vaishampayan, Deep

    2009-01-01

    This thesis presents the laboratory test data on Bisphenol A epoxy insulation.This thesis work deals with electrical, mechanical and thermal analysis of Bisphenol A epoxy resin. The main aim of this thesis work was to examine if dry and wet aging changes the glass transition temperature (Tg) of the epoxies and measure the impact on the complex permittivity under different ageing conditions namely dry and wet. During ageing the samples (epoxy discs and dog bones) were kept in water at 20°C, 45...

  2. Radiation Induced Aging Effects in Polymeric Cable Insulators at CERN. Compilation of the DSC and ATR-FTIR data on irradiated CERN cables.

    CERN Document Server

    Sorin, I

    2009-01-01

    This second part of the Report on Radiation Induced Aging Effects in Polymeric Cable Insulators at CERN [1] summarizes in a tabulated form all the experimental DSC results obtained in this work, concerning the life-time evaluation of the selected CERN cables irradiated in different conditions. Several examples of DSC curves and ATR-FTIR spectra were included to support the future polymeric materials analysis. Information on the experimental conditions, the instruments, the basic concept of life-time evaluation using the DSC data, as well as the examples of data processing and interpretation are presented and discussed in reference [1].

  3. Evaluation of the aging of polymeric drilling fluids to oil wells; Avaliacao do envelhecimento de fluidos de perfuracao polimericos para pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Farias, K.V.; Amorim, L.V. [Universidade Federal de Campina Grande, PB (Brazil). Unidade Academica de Engenharia Mecanica, UAEM/CCT - UFCG], e-mail: kassie@dem.ufcg.edu.br; Leite, R.S. [Universidade Federal de Campina Grande, PB (Brazil). Graduacao Engenharia de Materiais; Lira, H.L. [Universidade Federal de Campina Grande, PB (Brazil). Unidade Academica de Engenharia de Materiais, UAEMa/ CCT - UFCG

    2010-07-01

    The aim of this work is to evaluate the aging of polymeric drilling fluids to oil wells, from the rheological, filtration and lubricity properties in the temperatures 100 degree F ({approx} 38 degree C) and 150 degree F ({approx} 66 degree C). The results had been compared with a standard fluid used for the oil industry and had evidenced that the polymeric fluids had presented good thermal stability, presenting a small reduction in the rheological properties and better values of lubricity coefficient that a reference fluid. (author)

  4. Mechanical reliability of porous low-k dielectrics for advanced interconnect: Study of the instability mechanisms in porous low-k dielectrics and their mediation through inert plasma induced re-polymerization of the backbone structure

    Science.gov (United States)

    Sa, Yoonki

    Continuous scaling down of critical dimensions in interconnect structures requires the use of ultralow dielectric constant (k) films as interlayer dielectrics to reduce resistance-capacitance delays. Porous carbon-doped silicon oxide (p-SiCOH) dielectrics have been the leading approach to produce these ultralow-k materials. However, embedding of porosity into dielectric layer necessarily decreases the mechanical reliability and increases its susceptibility to adsorption of potentially deleterious chemical species during device fabrication process. Among those, exposure of porous-SiCOH low-k (PLK) dielectrics to oxidizing plasma environment causes the increase in dielectric constant and their vulnerability to mechanical instability of PLKs due to the loss of methyl species and increase in moisture uptake. These changes in PLK properties and physical stability have been persisting challenges for next-generation interconnects because they are the sources of failure in interconnect integration as well as functional and physical failures appearing later in IC device manufacturing. It is therefore essential to study the fundamentals of the interactions on p-SiCOH matrix induced by plasma exposure and find an effective and easy-to-implement way to reverse such changes by repairing damage in PLK structure. From these perspectives, the present dissertation proposes 1) a fundamental understanding of structural transformation occurring during oxidative plasma exposure in PLK matrix structure and 2) its restoration by using silylating treatment, soft x-ray and inert Ar-plasma radiation, respectively. Equally important, 3) as an alternative way of increasing the thermo-mechanical reliability, PLK dielectric film with an intrinsically robust structure by controlling pore morphology is fabricated and investigated. Based on the investigations, stability of PLK films studied by time-dependent ball indentation tester under the elevated temperature, variation in film thickness and

  5. Aging of polymers due to ionizing radiation as investigated on some polymeric electrical insulating materials

    International Nuclear Information System (INIS)

    The reliability of the qualifying procedures suggested by international standards relating to accelerated aging tests on commercial organic electrical insulating materials has been evaluated. Several types of ethylene-propylene rubbers (EPR) and cycloaliphatic epoxy resin (EP), widely used as electrical insulating materials have been evaluated. Several types of EPR and EP used in nuclear power plants have been gamma-irradiated under conditions of different total dose and different irradiation intensity. In the case of EPRs, the effect of irradiation has been evaluated on the basis of tensile tests, whereas in the case of EP resin - from the changes in glass transition temperature. Under the action of gamma radiation both crosslinking and degradation take place and the dependence of these two processes on the irradiation parameters (dose and dose intensity) differs for various materials. It is therefore important to individuate the testing conditions for each kind of insulating material. (author)

  6. Aging effects of plasma polymerized ethylenediamine (PPEDA) thin films on cell-adhesive implant coatings

    Energy Technology Data Exchange (ETDEWEB)

    Testrich, H., E-mail: holger.testrich@uni-greifswald.de [University of Greifswald, Institute of Physics, Felix-Hausdorff Str. 6, 17489 Greifswald (Germany); Rebl, H. [University of Rostock, Biomedical Research Center, Department of Cell Biology, Schillingallee 69, 18057 Rostock (Germany); Finke, B.; Hempel, F. [Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff Str. 2, 17489 Greifswald (Germany); Nebe, B. [University of Rostock, Biomedical Research Center, Department of Cell Biology, Schillingallee 69, 18057 Rostock (Germany); Meichsner, J. [University of Greifswald, Institute of Physics, Felix-Hausdorff Str. 6, 17489 Greifswald (Germany)

    2013-10-15

    Thin plasma polymer films from ethylenediamine were deposited on planar substrates placed on the powered electrode of a low pressure capacitively coupled 13.56 MHz discharge. The chemical composition of the plasma polymer films was analyzed by Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) as well as by X-ray photoelectron spectroscopy (XPS) after derivatization of the primary amino groups. The PPEDA films undergo an alteration during the storage in ambient air, particularly, due to reactions with oxygen. The molecular changes in PPEDA films were studied over a long-time period of 360 days. Simultaneously, the adhesion of human osteoblast-like cells MG-63 (ATCC) was investigated on PPEDA coated corundum blasted titanium alloy (Ti-6Al-4V), which is applied as implant material in orthopedic surgery. The cell adhesion was determined by flow cytometry and the cell shape was analyzed by scanning electron microscopy. Compared to uncoated reference samples a significantly enhanced cell adhesion and proliferation were measured for PPEDA coated samples, which have been maintained after long-time storage in ambient air and additional sterilization by γ−irradiation. - Highlights: • Development of cell-adhesive nitrogen-rich coatings for biomedical applications. • Plasma polymer films from low pressure 13.56 MHz discharge in argon-ethylenediamine. • Enhanced osteoblast adhesion/proliferation on coated implant material (Ti-6Al-4V). • Despite film aging over 360 days the enhanced cell adhesion of the coating remains. • No influence of additional y-sterilization on the enhanced cell adhesion.

  7. Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates

    Science.gov (United States)

    Simpson, Joycely O. (Inventor); St.Clair, Terry L. (Inventor)

    1999-01-01

    A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers. acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors, in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors. weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 1000 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

  8. An improved model to estimate trapping parameters in polymeric materials and its application on normal and aged low-density polyethylenes

    International Nuclear Information System (INIS)

    Trapping parameters can be considered as one of the important attributes to describe polymeric materials. In the present paper, a more accurate charge dynamics model has been developed, which takes account of charge dynamics in both volts-on and off stage into simulation. By fitting with measured charge data with the highest R-square value, trapping parameters together with injection barrier of both normal and aged low-density polyethylene samples were estimated using the improved model. The results show that, after long-term ageing process, the injection barriers of both electrons and holes is lowered, overall trap depth is shallower, and trap density becomes much greater. Additionally, the changes in parameters for electrons are more sensitive than those of holes after ageing

  9. An improved model to estimate trapping parameters in polymeric materials and its application on normal and aged low-density polyethylenes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ning, E-mail: nl4g12@soton.ac.uk; He, Miao; Alghamdi, Hisham; Chen, George [School of Electronic and Computer Science, University of Southampton, Southampton (United Kingdom); Fu, Mingli; Li, Ruihai; Hou, Shuai [Electric Power Research Institute of China Southern Power Grid, Guangzhou (China)

    2015-08-14

    Trapping parameters can be considered as one of the important attributes to describe polymeric materials. In the present paper, a more accurate charge dynamics model has been developed, which takes account of charge dynamics in both volts-on and off stage into simulation. By fitting with measured charge data with the highest R-square value, trapping parameters together with injection barrier of both normal and aged low-density polyethylene samples were estimated using the improved model. The results show that, after long-term ageing process, the injection barriers of both electrons and holes is lowered, overall trap depth is shallower, and trap density becomes much greater. Additionally, the changes in parameters for electrons are more sensitive than those of holes after ageing.

  10. Mechanical and Electrical Ageing Effects on the Long-Term Stretching of Silicone Dielectric Elastomers with Soft Fillers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Zakaria, Shamsul Bin; Yu, Liyun;

    2016-01-01

    backbone. Such elastomers are prepared by adding soft fillers to a strong and relatively stiff elastomer, Elastosil LR3043/50. The long-term stability of the materials is tested by straining the elastomers 60% statically for up to 3 months. The results show that soft fillers significantly influence the......Dielectric elastomer materials for actuators need to be soft and stretchable while possessing high dielectric permittivity. Soft silicone elastomers can be obtained through the use of silicone oils, while enhanced permittivity can be obtained through the use of dipolar groups on the polymer...... long-term stability of silicone elastomers, with electrical breakdown strength being the most influenced. Especially high concentrations of silicone oils should be avoided for long-term mechanical stability....

  11. Evidence for the molecular-scale origin of the suppression of physical ageing in confined polymer: fluorescence and dielectric spectroscopy studies of polymer-silica nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Priestley, Rodney D [Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 (United States); Rittigstein, Perla [Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 (United States); Broadbelt, Linda J [Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 (United States); Fukao, Koji [Department of Polymer Science and Engineering, Kyoto Institute of Technology, Kyoto 606-8585 (Japan); Torkelson, John M [Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208 (United States)

    2007-05-23

    Fluorescence spectroscopy was used to characterize the rate of physical ageing at room temperature in nanocomposites of silica (10-15 nm diameter) nanoparticles in poly(methyl methacrylate) (PMMA). The physical ageing rate was reduced by more than a factor of 20 in 0.4 vol% silica-PMMA nanocomposites relative to neat PMMA. The molecular-scale origin of this nearly complete arresting of physical ageing was investigated with dielectric spectroscopy. The strength of the {beta} relaxation process was reduced by nearly 50% in the nanocomposite relative to neat PMMA. This reduced strength of the {beta} process results from dipoles (ester groups) having hindered motions or being virtually immobile on the timescale being probed at a frequency of 100 Hz. This hindered mobility results from hydrogen bonding between PMMA ester side groups and hydroxyl units on the surface of the silica nanoparticles. In contrast, no reduction in physical ageing rate was observed upon addition of silica to polystyrene, which cannot form hydrogen bonds with the silica surfaces. Thus, the molecular origin of the suppressed physical ageing in silica-PMMA nanocomposites is the interfacial hydrogen bonding, which leads to a major reduction in the strength of the {beta} process, i.e., the {beta} process is largely responsible for the observed physical ageing.

  12. Dielectric characterization of high-performance spaceflight materials

    Science.gov (United States)

    Kleppe, Nathan; Nurge, Mark A.; Bowler, Nicola

    2015-03-01

    As commercial space travel increases, the need for reliable structural health monitoring to predict possible weaknesses or failures of structural materials also increases. Monitoring of these materials can be done through the use of dielectric spectroscopy by comparing permittivity or conductivity measurements performed on a sample in use to that of a pristine sample from 100 μHz to 3 GHz. Fluctuations in these measured values or of the relaxation frequencies, if present, can indicate chemical or physical changes occurring within the material and the possible need for maintenance/replacement. In this work, we establish indicative trends that occur due to changes in dielectric spectra during accelerated aging of various high-performance polymeric materials: ethylene vinyl alcohol (EVOH), Poly (ether ether ketone) (PEEK), polyphenylene sulfide (PPS), and ultra-high molecular weight polyethylene (UHMWPE). Uses for these materials range from electrical insulation and protective coatings to windows and air- or space-craft parts that may be subject to environmental damage over long-term operation. Samples were prepared by thermal exposure and, separately, by ultraviolet/water-spray cyclic aging. The aged samples showed statistically-significant trends of either increasing or decreasing real or imaginary permittivity values, relaxation frequencies, conduction or the appearance of new relaxation modes. These results suggest that dielectric testing offers the possibility of nondestructive evaluation of the extent of age-related degradation in these materials.

  13. Elektroaktive polymerer

    DEFF Research Database (Denmark)

    West, K.

    Traditionelt tænker vi på polymerer (plastik) som elektrisk isolerende materialer - det som er udenpå ledningerne. I dag kender vi imidlertid også polymerer med intrinsisk elektrisk ledningsevne, og plast er på vej ind i anvendelser, der tidligereudelukkende var baseret på metaller og uorganiske...... halvledere. Hertil kommer, at en del af de ledende polymerer kan stimuleres til at skifte mellem en ledende og en halvledende tilstand, hvorved de ændret både form og farve. I foredraget gives der enrække eksempler på anvendelse af polymerer som elektriske komponenter - rækkende fra polymer elektronik over...

  14. Effect of (Ca0.8Sr0.2)0.6La0.267TiO3 on Phase, Microstructure, and Microwave Dielectric Properties of Mg0.95Zn0.05TiO3 Synthesized by Polymeric Precursor Method

    Science.gov (United States)

    Naeem, Abdul; Ullah, Asad; Mahmood, Tahira; Iqbal, Yaseen; Mahmood, Asad; Hamayun, Muhammad

    2016-08-01

    A number of compounds in the (1 - x)Mg0.95Zn0.05TiO3- x(Ca0.8Sr0.2)0.6 La0.267TiO3 ( x = 0 to 0.25) composition series have been obtained via a polymeric precursor route to investigate the effect of increasing (Ca0.8Sr0.2)0.6La0.267TiO3 proportion on the phase, microstructure, and microwave dielectric properties of the sintered ceramics. Composite powders having nanometric particles were obtained by calcining the precursors at 700°C. Refinement results revealed that these samples comprised a mixture of Mg0.95Zn0.05TiO3 and (Ca0.8Sr0.2)0.6La0.267TiO3 ceramics. A combination of optimum microwave dielectric properties, i.e., dielectric constant of 25.17, quality factor of 58,754 GHz, and temperature coefficient of resonant frequency of -5.8 ppm/°C, was achieved for the x = 0.2 composition sintered at 1200°C.

  15. Effect of age and chemical treatments on characteristic parameters for active and porous sublayers of polymeric composite membranes.

    Science.gov (United States)

    Benavente, J; Vázquez, M I

    2004-05-15

    Changes in the transport parameters and the chemical nature of the surface of composite polyamide/polysulfone membranes due to both aging and treatment with chemical products (HCl, H(3)NO, and NaOH) have been considered. Hydraulic and salt permeability were obtained from water flow and salt diffusion measurements, respectively, and their values seem to indicate a modification in the structural parameters (porosity/thickness) of aging samples, while HCl and HNO(3) treatments will act in the opposite way. Chemical modifications in the membrane surfaces were studied by X-ray photoelectron spectroscopy (XPS), which mainly show the effect of H(3)NO and HCl on the polyamide active layer of the membranes (polyamide oxidation), but no chemical damage for that sublayer. Electrical characterization of both sublayers of the composite membranes were determined from impedance spectroscopy (IS) measurements using equivalent circuits as models, and these results indicate: (i) a strong increase of the membrane electrical resistance as a consequence of aging, mainly that associated with the active sublayer (30 times higher for an old sample than for a fresh one) and treatment with NaOH; (ii) the reduction of this effect when the samples were treated with HCl and HNO(3) solutions. Changes in the values of the electrical resistance of the composite membranes are in agreement with those obtained for permeabilities, but the electrical parameter also allows the determination of the contribution of each sublayer. PMID:15082393

  16. Method of Making Thermally Stable, Piezoelectric and Proelectric Polymeric Substrates

    Science.gov (United States)

    Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

    1999-01-01

    A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium: applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

  17. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  18. Aluminum nanoparticle/acrylate copolymer nanocomposites for dielectric elastomers with high dielectric constants

    Science.gov (United States)

    Hu, Wei; Zhang, Suki N.; Niu, Xiaofan; Liu, Chao; Pei, Qibing

    2014-03-01

    Dielectric elastomers are useful for large-strain actuation and energy harvesting. Their application has been limited by their low dielectric constants and consequently high driving voltage. Various fillers with high dielectric constants have been incorporated into different elastomer systems to improve the actuation strain, force output and energy density of the compliant actuators and generators. However, agglomeration may happen in these nanocomposites, resulting in a decrease of dielectric strength, an increase of leakage current, and in many instances the degree of enhancement of the dielectric constant. In this work, we investigated aluminum nanoparticles as nanofillers for acrylate copolymers. This metallic nanoparticle was chosen because the availability of free electrons could potentially provide an infinite value of dielectric constant as opposed to dielectric materials including ferroelectric nanocrystals. Moreover, aluminum nanoparticles have a self-passivated oxide shell effectively preventing the formation of conductive path. The surfaces of the aluminum nanoparticles were functionalized with methacrylate groups to assist the uniform dispersion in organic solutions and additionally enable copolymerization with acrylate copolymer matrix during bulk polymerization, and thus to suppress large range drifting of the nanoparticles. The resulting Al nanoparticle-acrylate copolymer nanocomposites were found to exhibit higher dielectric constant and increased stiffness. The leakage current under high electric fields were significantly lower than nanocomposites synthesized without proper nanoparticle surface modification. The dielectric strengths of the composites were comparable with the pristine polymers. In dielectric actuation evaluation, the actuation force output and energy specific work density were enhanced in the nanocomposites compared to the pristine copolymer.

  19. Study of accelerated aging of polymeric surge arresters and insulators used in high voltage lines; Estudo sobre o envelhecimento acelerado de para-raios e isoladores polimericos usados em linhas de alta tensao

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira Junior, Joao B. de; Castro Junior, Joao B. de; Silva, Maria Elisa S.R. e; Freitas, Roberto F.S.; Sousa, Ricardo G. de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Quimica. Lab. Ciencia e Tecnologia de Polimeros; Souza, Breno P.G. de [CEMIG Distribuicao S.A., Belo Horizonte, MG (Brazil)], e-mail: sousarg@ufmg.br

    2011-07-01

    The use of polymeric materials in the electrical system has dramatically increased in recent years, in quantity as well as in quality. However, the use of these materials has been very empirical, being necessary a more directed and well based study towards their application in energy sector, especially concerning their early deterioration. In this study, the behavior of some surge arresters and insulators, used in power lines, after suffering aging artificial weathering chamber, was investigated. The absorption spectra in the infrared (FTIR) was used as analytical technique for study of aging. Of the five samples tested, only one showed an oxidation process after 1500 hours of artificial weathering. (author)

  20. Chain Reaction Polymerization.

    Science.gov (United States)

    McGrath, James E.

    1981-01-01

    The salient features and importance of chain-reaction polymerization are discussed, including such topics as the thermodynamics of polymerization, free-radical polymerization kinetics, radical polymerization processes, copolymers, and free-radical chain, anionic, cationic, coordination, and ring-opening polymerizations. (JN)

  1. Polymeric matrix materials for infrared metamaterials

    Science.gov (United States)

    Dirk, Shawn M; Rasberry, Roger D; Rahimian, Kamyar

    2014-04-22

    A polymeric matrix material exhibits low loss at optical frequencies and facilitates the fabrication of all-dielectric metamaterials. The low-loss polymeric matrix material can be synthesized by providing an unsaturated polymer, comprising double or triple bonds; partially hydrogenating the unsaturated polymer; depositing a film of the partially hydrogenated polymer and a crosslinker on a substrate; and photopatterning the film by exposing the film to ultraviolet light through a patterning mask, thereby cross-linking at least some of the remaining unsaturated groups of the partially hydrogenated polymer in the exposed portions.

  2. Fabrication of triazinedithiol functional polymeric nanofilm by potentiostatic polymerization on aluminum surface

    International Nuclear Information System (INIS)

    The functional polymeric nanofilm of 6-(N-allyl-1,1,2,2-tetrahydroperfluorodecyl)amino-1,3,5-triazine-2, 4-dithiol monosodium (AF17N) was prepared on pure aluminum surface by potentiostatic polymerization at different potentials. The thickness and weight of polymeric nanofilm increased proportionally to electro-polymerization potential following linear equation. The chemical structure of nanofilm was characterized by Fourier transform-infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Adsorption peaks in FT-IR and C1s, N1s, S2p, F1s and Al2p peaks in XPS spectra indicated that the polymeric nanofilm was poly(6-(N-allyl-1,1,2,2-tetrahydroperfluorodecyl)amino-1,3,5-triazine-2, 4-disulfide) (PAF17). The morphologies of polymeric nanofilm were also observed by atomic force microscopy (AFM). All the results showed that the optimal electro-polymerization potential and time were 8 V and 20 s, respectively. Uniform and compact nanofilm of PAF17 could be obtained under these conditions. It is expected that this technique will be applied in the preparation of lubricating, dielectric and hydrophobic surface on aluminum substrate.

  3. Degradation of High Voltage Polymeric Insulators in Arid Desert's Simulated Environmental Conditions

    Directory of Open Access Journals (Sweden)

    Yasin Khan

    2009-01-01

    Full Text Available Problem statement: High Voltage (HV polymeric insulators are replacing ceramic insulator commonly used for HV outdoor networks due to their ease of handling, reliability and cost. However, their long term performance and reliability are major concerns to power utilities. Approach: To investigate their performance in arid desert's conditions, two types of HV composite insulators were aged as per International Electrochemical Commission (IEC standard-61109. Additional test samples were subjected to accelerated aging conditions simulating the actual Ultraviolet (UV radiation intensity and temperature in the inland desert. Results: This study described the experimental results of the effects of thermo electric stress and UV radiations on the polymeric insulators aged under two conditions i.e., as per IEC standard and modified IEC standard that simulates the inland arid desert. The tests results after the artificial accelerated aging indicated that the dielectric response of thermoplastic insulators under the tested thermo-electric cum UV-irradiations outperforms Silicone rubber insulators.Conclusion: From the obtained results it will be easy to assess the performance and suitability of composite insulators for their applications in arid desert environments.

  4. Effect of Insulation Properties on the Field Grading of Solid Dielectric DC Cable

    DEFF Research Database (Denmark)

    Boggs, S.; Damon, Dwight Hill; Hjerrild, Jesper; Holbøll, Joachim; Henriksen, Mogens

    2001-01-01

    The development of solid dielectric dc transmission class cable is a priority throughout much of the world, to avoid risks associated with placing hydrocarbon fluids in underwater environments. The conductivity of polymeric solid dielectrics tends to be a strong function of temperature and electric...

  5. Dielectric Actuation of Polymers

    OpenAIRE

    Niu, Xiaofan

    2013-01-01

    Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy den...

  6. Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

    Science.gov (United States)

    Simpson, Joycelyn O. (Inventor); St.Claire, Terry L. (Inventor)

    2002-01-01

    A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared, This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches. adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrates; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

  7. "Click" i polymerer 2

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2012-01-01

    "Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer......"Click"-reaktioner til fremstilling af ledende polymerer med funktionelle håndtag og bipolymermaterialer...

  8. Anticipating electrical breakdown in dielectric elastomer actuators

    Science.gov (United States)

    Muffoletto, Daniel P.; Burke, Kevin M.; Zirnheld, Jennifer L.

    2013-04-01

    The output strain of a dielectric elastomer actuator is directly proportional to the square of its applied electric field. However, since the likelihood of electric breakdown is elevated with an increased applied field, the maximum operating electric field of the dielectric elastomer is significantly derated in systems employing these actuators so that failure due to breakdown remains unlikely even as the material ages. In an effort to ascertain the dielectric strength so that stronger electric fields can be applied, partial discharge testing is used to assess the health of the actuator by detecting the charge that is released when localized instances of breakdown partially bridge the insulator. Pre-stretched and unstretched samples of VHB4910 tape were submerged in dielectric oil to remove external sources of partial discharges during testing, and the partial discharge patterns were recorded just before failure of the dielectric sample.

  9. Polymerization Reactor Engineering.

    Science.gov (United States)

    Skaates, J. Michael

    1987-01-01

    Describes a polymerization reactor engineering course offered at Michigan Technological University which focuses on the design and operation of industrial polymerization reactors to achieve a desired degree of polymerization and molecular weight distribution. Provides a list of the course topics and assigned readings. (TW)

  10. Preparation of Superhydrophobic Polymeric Film on Aluminum Plates by Electrochemical Polymerization

    Directory of Open Access Journals (Sweden)

    Juan Xu

    2009-11-01

    Full Text Available 6-(N-Allyl-1,1,2,2-tetrahydroperfluorododecylamino-1,3,5-triazine-2,4-dithiol monosodium (ATP was used to prepare polymeric thin films on pure aluminum plates to achieve a superhydrophobic surface. The electrochemical polymerization process of ATP on aluminum plates in NaNO2 aqueous solution and the formation of poly(6-(N-allyl-1,1,2,2-tetrahydroperfluorododecylamino-1,3,5-triazine-2,4-dithiol (PATP thin film were studied by means of optical ellipsometry and film weight. The chemical structure of the polymeric film is investigated using FT-IR spectra and X-ray photoelectron spectroscopy (XPS. Contact angle goniometry was applied to measure the contact angles with distilled water drops at ambient temperature. The experimental results indicate that the polymeric film formed on pure aluminum plates exhibits superhydrophobic properties with a distilled water contact angle of 153°. The electrochemical polymerization process is time-saving, inexpensive, environmentally friendly and fairly convenient to carry out. It is expected that this technique will advance the production of superhydrophobic materials with new applications on a large scale. Moreover, this kind of polymeric thin film can be used as a dielectric material due to its insulating features.

  11. Accelerating Dielectrics Design Using Thinking Machines

    Science.gov (United States)

    Ramprasad, R.

    2013-03-01

    High energy density capacitors are required for several pulsed power and energy storage applications, including food preservation, nuclear test simulations, electric propulsion of ships and hybrid electric vehicles. The maximum electrostatic energy that can be stored in a capacitor dielectric is proportional to its dielectric constant and the square of its breakdown field. The current standard material for capacitive energy storage is polypropylene which has a large breakdown field but low dielectric constant. We are involved in a search for new classes of polymers superior to polypropylene using first principles computations combined with statistical and machine learning methods. Essential to this search are schemes to efficiently compute the dielectric constant of polymers and the intrinsic dielectric breakdown field, as well as methods to determine the stable structures of new classes of polymers and strategies to efficiently navigate through the polymer chemical space offered by the periodic table. These methodologies have been combined with statistical learning paradigms in order to make property predictions rapidly, and promising classes of polymeric systems for energy storage applications have been identified. This work is being supported by the Office of Naval Research.

  12. Polymerization of organized monomers

    Directory of Open Access Journals (Sweden)

    Stoiljković Dragoslav M.

    2004-01-01

    Full Text Available The current explanations of olefin and vinyl monomer polymerization propose that monomer molecules are successively added one by one to the growing polymer chain. This may be true if the monomer molecules exist as individual species in a polymerizing system, e.g. in dilute solutions of monomer. There are cases, however, in which monomer molecules are organized: bulk liquid monomer, solid monomer, a monomer monolayer adsorbed on a support, etc. Various supra-molecular species and particles of monomer exist in such cases. In the 1960-ties, Semenov, Kargin and Kabanov proposed a theory of organized monomer polymerization. In the last 25 years, our research group has further developed and applied that theory to various polymerizing systems: the radical polymerization of compressed ethene gas, the radical polymerization of liquid methyl methacrylate, olefin polymerization by transition metals and by Al-based catalysts. An outline of the main achievements are presented in this article.

  13. Dielectric Laser Acceleration

    OpenAIRE

    England, R. Joel; Noble, Robert J.; Wu, Ziran; Qi, Minghao

    2013-01-01

    We describe recent advances in the study of particle acceleration using dielectric near-field structures driven by infrared lasers, which we refer to as Dielectric Laser Accelerators. Implications for high energy physics and other applications are discussed.

  14. Aging.

    Science.gov (United States)

    Park, Dong Choon; Yeo, Seung Geun

    2013-09-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  15. Dielectrics in electric fields

    CERN Document Server

    Raju, Gorur G

    2003-01-01

    Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.

  16. Lattices of dielectric resonators

    CERN Document Server

    Trubin, Alexander

    2016-01-01

    This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

  17. Study of the adhesive properties versus stability/aging of hernia repair meshes after deposition of RF activated plasma polymerized acrylic acid coating.

    Science.gov (United States)

    Rivolo, Paola; Nisticò, Roberto; Barone, Fabrizio; Faga, Maria Giulia; Duraccio, Donatella; Martorana, Selanna; Ricciardi, Serena; Magnacca, Giuliana

    2016-08-01

    In order to confer adhesive properties to commercial polypropylene (PP) meshes, a surface plasma-induced deposition of poly-(acrylic acid) (PPAA) is performed. Once biomaterials were functionalized, different post-deposition treatments (i.e. water washing and/or thermal treatments) were investigated with the aim of monitoring the coating degradation (and therefore the loss of adhesion) after 3months of aging in both humid/oxidant (air) and inert (nitrogen) atmospheres. A wide physicochemical characterization was carried out in order to evaluate the functionalization effectiveness and the adhesive coating homogeneity by means of static water drop shape analysis and several spectroscopies (namely, FTIR, UV-Visible and X-ray Photoemission Spectroscopy). The modification of the adhesion properties after post-deposition treatments as well as aging under different storage atmospheres were investigated by means of Atomic Force Microscopy (AFM) used in Force/Distance (F/D) mode. This technique confirms itself as a powerful tool for unveiling the surface adhesion capacity as well as the homogeneity of the functional coatings along the fibers. Results obtained evidenced that post-deposition treatments are mandatory in order to remove all oligomers produced during the plasma-treatment, whereas aging tests evidenced that these devices can be simply stored in presence of air for at least three months without a meaningful degradation of the original properties. PMID:27157754

  18. Conductivity As A Measure Of Degree Of Polymerization

    Science.gov (United States)

    Dean, David L.; Walsh, Robert K.

    1993-01-01

    In improved method of dielectric monitoring of process of polymerization of mixed ingredients of polymeric material, emphasis placed on measurement of conductivity rather than permittivity. Conductivity tends to change more during curing process than permittivity does, is less dependent on frequency, and more-sensitive and more-reliable indicator of progress of cure. Conductivity used to compute quantity called "ion viscosity," which relates to classical viscosity of fluid. During cure of typical polymer, ion viscosity varies over wide range, eventually rising to plateau toward end of cure.

  19. Conducting Polymeric Materials

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    2016-01-01

    The overall objective of this collection is to provide the most recent developments within the various areas of conducting polymeric materials. The conductivity of polymeric materials is caused by electrically charged particles, ions, protons and electrons. Materials in which electrons are the ch...... awarded the Nobel Prize in chemistry “for the discovery and development of conductive polymers”....

  20. Step-Growth Polymerization.

    Science.gov (United States)

    Stille, J. K.

    1981-01-01

    Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

  1. Applied bioactive polymeric materials

    CERN Document Server

    Carraher, Charles; Foster, Van

    1988-01-01

    The biological and biomedical applications of polymeric materials have increased greatly in the past few years. This book will detail some, but not all, of these recent developments. There would not be enough space in this book to cover, even lightly, all of the major advances that have occurred. Some earlier books and summaries are available by two of this book's Editors (Gebelein & Carraher) and these should be consul ted for additional information. The books are: "Bioactive Polymeric Systems" (Plenum, 1985); "Polymeric Materials In Medication" (Plenum, 1985); "Biological Acti vi ties of Polymers" (American Chemical Society, 1982). Of these three, "Bioacti ve Polymeric Systems" should be the most useful to a person who is new to this field because it only contains review articles written at an introductory level. The present book primarily consists of recent research results and applications, with only a few review or summary articles. Bioactive polymeric materials have existed from the creation of life...

  2. Resonant dielectric metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Loui, Hung; Carroll, James; Clem, Paul G; Sinclair, Michael B

    2014-12-02

    A resonant dielectric metamaterial comprises a first and a second set of dielectric scattering particles (e.g., spheres) having different permittivities arranged in a cubic array. The array can be an ordered or randomized array of particles. The resonant dielectric metamaterials are low-loss 3D isotropic materials with negative permittivity and permeability. Such isotropic double negative materials offer polarization and direction independent electromagnetic wave propagation.

  3. Infrared Dielectric Resonator Metamaterial

    CERN Document Server

    Ginn, James C; Peters, David W; Wendt, Joel R; Stevens, Jeffrey O; Hines, Paul F; Basilio, Lorena I; Warne, Larry K; Ihlefeld, Jon F; Clem, Paul G; Sinclair, Michael B

    2011-01-01

    We demonstrate, for the first time, an all-dielectric metamaterial resonator in the mid-wave infrared based on high-index tellurium cubic inclusions. Dielectric resonators are desirable compared to conventional metallo-dielectric metamaterials at optical frequencies as they are largely angular invariant, free of ohmic loss, and easily integrated into three-dimensional volumes. With these low-loss, isotropic elements, disruptive optical metamaterial designs, such as wide-angle lenses and cloaks, can be more easily realized.

  4. Dielectric properties of nanosilica filled epoxy nanocomposites

    Indian Academy of Sciences (India)

    M G VEENA; N M RENUKAPPA; KUNIGAL N SHIVAKUMAR; S SEETHARAMU

    2016-04-01

    This paper presents the development of epoxy-silica nanocomposites and characterized for dielectric properties. The effect of nanosilica loading (0–20 wt%), frequency, temperature and sea water aging on these properties was studied. Transmission electron microscopy (TEM) analysis of the samples showed an excellent dispersion. However, at higher silica loading TEM showed inter-contactity of the particles. The dielectric constant (υ') increased with silica loading and reached an optimum at about 10 wt%. The υ' of the nanocomposites showed linear decrease with frequency whereas AC conductivity (σac) increases. The σac and υ' increased marginally with temperature and sea water aging.

  5. Organometallic Polymeric Conductors

    Science.gov (United States)

    Youngs, Wiley J.

    1997-01-01

    over 150 days in air at ambient temperature. The conductivity of the films dropped only half an order of magnitude in that time. Films aged under vacuum at ambient temperature diminished slightly in conductivity in the first day, but did not change thereafter. An experimental design approach will be applied to maximize the efficiency of the laboratory effort. The material properties (initial and long term) will also be monitored and assessed. The experimental results will add to the existing database for electrically conductive polymer materials. Attachments: 1) Synthesis Crystal Structure, and Polymerization of 1,2:5,6:9,10-Tribenzo-3,7,11,13-tetradehydro(14) annulene. 2) Reinvestigation of the Photocyclization of 1,4-Phenylene Bis(phenylmaleic anhydride): Preparation and Structure of (5)Helicene 5,6:9,10-Dianhydride. 3) Preparation and Structure Charecterization of a Platinum Catecholate Complex Containing Two 3-Ethynyltheophone Groups. and 4) Rigid-Rod Polymers Based on Noncoplanar 4,4'-Biphenyldiamines: A Review of Polymer Properties vs Configuration of Diamines.

  6. Shock-induced electrical switching in polymeric films

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R. A.

    1979-01-01

    Several of the compressed magnetic field generators described at this conference use polymeric films to insulate explosively driven armatures from coils surrounding the armatures. Optimum device performance is achieved when the films remain electrically insulating prior to impact of the armatures but switch to highly conducting states upon impact on the film. The electrical switching properties of commercially available polymer films with high dielectric strength are reported.

  7. Promjena mehaničkih svojstava procesom starenja polimernih tkanina otpornih na cijepanje i trganje* / Effect of Aging on Mechanical Properties of Polymeric Ripstop Fabrics

    Directory of Open Access Journals (Sweden)

    Anđelko OČIĆ

    2013-04-01

    Full Text Available Polimerne tkanine otporne na cijepanje i trganje* (e. ripstop često seupotrebljavaju u vanjskim uvjetima. Njihova osjetljivost na atmosferske uvjete važan je faktor pri izboru tkanine odgovarajućega sirovinskog sastava. U ovom radu tkanine otporne na cijepanje i trganje izložene su djelovanju umjetnih atmosferskih uvjeta, a njihova mehanička svojstva analizirana su prije i nakon izlaganja 1 000 sati ubrzanom starenju radi određivanja nastalih promjena. Ispitane su tri vrste tkanine. Ispitane tkanine načinjene su od poliamidnog vlakna prevučenog elastoplastomernim poliuretanom, poliamidnog vlakna prevučenog elastoplastomernim poliuretanom i metaliziranog aluminijem te poliesterskog vlakna prevučenog polikarbonatom. Mehanička svojstva izravno ovise o vrsti materijala i stupnju starenja, međutim iz rasteznih ispitivanja (i žilavosti udarnim opterećenjem i (ii rastezne čvrstoće sporim prirastom sile proizlazi da snižavanje mehaničkih svojstava ovisi i o brzini ispitivanja. Taj zaključak važan je pri odabiru parametara za izbor materijala izloženoga u vanjskim uvjetima. / Ripstop fabrics are commonly used for outdoor applications. Their sensitivity to atmospheric conditions is an important issue for materials selection. In this paper different ripstop materials have been exposed to artificial weathering conditions and their mechanical properties have been tested before and after 1,000 hours of accelerated weathering. Three different types of fabrics have been examined. Woven fabrics were made of (i ripstop polyamide coated with thermoplastic polyurethane, (ii ripstop polyamide coated with polyurethane and aluminum and (iii polycarbonate-coated ripstop polyester. Mechanical properties are directly influenced by the type of fabrics and aging degree, but impact tensile tests and tensile tests with low force rate show that the deterioration of mechanical properties depends on testing velocity as well. This conclusion is an important

  8. Optics of dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas

    2002-01-01

    From the work carried out within the ph.d. project two topics have been selected for this thesis, namely emission of radiation by sources in dielectric microstructures, and planar photonic crystal waveguides. The work done within the first topic, emission of radiation by sources in dielectric mic...

  9. Terahertz Artificial Dielectric Lens

    Science.gov (United States)

    Mendis, Rajind; Nagai, Masaya; Wang, Yiqiu; Karl, Nicholas; Mittleman, Daniel M.

    2016-03-01

    We have designed, fabricated, and experimentally characterized a lens for the THz regime based on artificial dielectrics. These are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. For example, the well-known dielectric property, the refractive index, which usually has a value greater than unity, can have a value less than unity in an artificial dielectric. For our lens, the artificial-dielectric medium is made up of a parallel stack of 100 μm thick metal plates that form an array of parallel-plate waveguides. The convergent lens has a plano-concave geometry, in contrast to conventional dielectric lenses. Our results demonstrate that this lens is capable of focusing a 2 cm diameter beam to a spot size of 4 mm, at the design frequency of 0.17 THz. The results further demonstrate that the overall power transmission of the lens can be better than certain conventional dielectric lenses commonly used in the THz regime. Intriguingly, we also observe that under certain conditions, the lens boundary demarcated by the discontinuous plate edges actually resembles a smooth continuous surface. These results highlight the importance of this artificial-dielectric technology for the development of future THz-wave devices.

  10. Surface properties of dielectrics

    International Nuclear Information System (INIS)

    Importance of defects on dielectric behaviour (breakdown), mechanical behaviour (fracture, adhesion) and thermochemical behaviour of insulating materials is recalled. Then effect of a mechanical stress on breakdown voltage is studied. An experimental verification shows that fracture of Y2O3 is propagated in grain boundaries enriched in oxygen vacancies for a non stoichiometric sample by local variation of dielectric constant

  11. Investigation of Film Curing by Dielectric Analysis.

    Science.gov (United States)

    Guma, Noemi Candelaria

    1995-01-01

    Dielectric analysis (DEA) relies on the response of molecules to a changing electric field. Permittivity (epsilon^') is a parameter obtained from DEA, which is proportional to the amount of molecular alignment (or motion). A DEA methodology was developed to evaluate and classify the degree of cure of films, and to demonstrate the mechanism of the curing phenomenon at a molecular level. The model material employed in the study was Eudragit^circler RS30D, an aqueous-based film forming polymeric material, containing 20% acetyl tributyl citrate as plasticizer. The data showed changes in the dielectric behavior of the polymer molecules in films that were subjected to accelerated stability or improper curing conditions. These dielectric changes were also manifested as changes in the permeability characteristics of the film, which ultimately influenced the final performance of the dosage form. By monitoring the dielectric behavior of the coating material during a curing cycle, a classification of three stages of curing was developed, namely undercured, optimally cured, and overcured. The changes in dielectric properties of the film reflected the changes in molecular structure, which correlated with changes in permeability and surface morphology. Based on the data, a mechanism of improper cure was proposed, which contends that the curing phenomenon is driven by two major forces, namely: the heterogenous loss and/or redistribution of plasticizer molecules during the curing process and the development of strain in the film structure during the coating process. A mathematical equation was derived to predict the epsilon^' of film-coated beads based on the epsilon^ ' data of free films cured under the same conditions. The model is based on the premise that "equal epsilon^' denotes equal mobility" for the same material, whether as free film or applied onto a substrate. The DEA technique developed and the proposed rationale of the curing phenomenon may be useful in optimizing the

  12. Dielectric Properties of Dual-Frequency Reactive Mesogens before and after Photopolymerization

    Directory of Open Access Journals (Sweden)

    Takayuki Kumagai

    2014-02-01

    Full Text Available The dielectric properties of reactive mesogens before and after photopolymerization were investigated. Commercially available nematic reactive mesogens (RMS03-013C, Merck were measured and found to be dual-frequency liquid crystals. The property arose from the δ-relaxation process that was caused by rotational fluctuations parallel to the molecule’s long axis. After polymerization, the polymerized reactive mesogens still exhibited this dual-frequency property. The result was attributed to the β-relaxation process which arose from rotational fluctuations of localized parts of the main chain. The sign change of the dielectric anisotropy with increasing frequency after polymerization was opposite to the sign change before polymerization.

  13. Chelating polymeric membranes

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  14. Polyaniline coated cellulose fiber / polyvinyl alcohol composites with high dielectric permittivity and low percolation threshold

    OpenAIRE

    V. P. Anju; Sunil K. Narayanankutty

    2016-01-01

    Cost effective, high performance dielectric composites based on polyvinyl alcohol, cellulose fibers and polyaniline were prepared and the dielectric properties were studied as a function of fiber content, fiber dimensions and polyaniline content over a frequency range of 40 Hz to 30 MHz. The short cellulose fibers were size-reduced to micro and nano levels prior to coating with polyaniline. Fiber surface was coated with Polyaniline (PANI) by an in situ polymerization technique in aqueous medi...

  15. Radical polymerization of monoethyl itaconate

    OpenAIRE

    Katsikas Lynne; Nišević Nataša; Ignjatović Milka; Adamović Vladimir; Đakov Tatjana A.; Popović Ivanka G.

    2003-01-01

    The radical polymerization of monoethyl itaconate (MEI) was investigated in bulk and in solution at 60°C using a,a'-azobisisobutyronitrile as initiator. It was established that the obtained polymer poly(monoethyl itaconate) was insoluble in its monomer, implying that the bulk polymerization of MEI was a precipitation polymerization. The polymerization kinetics of MEI were discussed and compared to the polymerization kinetics of structurally similar alkyl itaconates. The homogeneous radical po...

  16. Dielectric Properties of Dual-Frequency Reactive Mesogens before and after Photopolymerization

    OpenAIRE

    Takayuki Kumagai; Hiroyuki Yoshida; Masanori Ozaki

    2014-01-01

    The dielectric properties of reactive mesogens before and after photopolymerization were investigated. Commercially available nematic reactive mesogens (RMS03-013C, Merck) were measured and found to be dual-frequency liquid crystals. The property arose from the δ-relaxation process that was caused by rotational fluctuations parallel to the molecule’s long axis. After polymerization, the polymerized reactive mesogens still exhibited this dual-frequency property. The result was attributed to th...

  17. Tunable Liquid Dielectric Antenna

    Directory of Open Access Journals (Sweden)

    Kamal Raj Singh Rajoriya

    2012-06-01

    Full Text Available This paper presents on modified the dielectric properties of liquid with varying salinity that was based on monopole structure. Dielectric resonator antennas (DRAs can be made with a wide range of materials and allow many excitation methods [2]. Pure water does not work at high frequency (> 1 GHz but increase in the salinity of water modifies the dielectric properties of water. Here proposed antenna shows that when the salinity increases in form of molar solution, the antenna was tuned at different frequency with increases return loss.

  18. Cast dielectric composite linear accelerator

    Science.gov (United States)

    Sanders, David M.; Sampayan, Stephen; Slenes, Kirk; Stoller, H. M.

    2009-11-10

    A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

  19. Dielectric properties of pure and lanthanum modified bismuth titanate thin films

    International Nuclear Information System (INIS)

    We investigated the dielectric properties of pure and lanthanum modified bismuth titanate thin films obtained by the polymeric precursor method. X-ray diffraction of the film annealed at 300 deg. C for 2 h indicates a disordered structure. Lanthanum addition increases gradually the dielectric permittivity of films, keeping unchanged their loss tangent. From C-V curve we can see no hysteresis behavior indicating the absence of domain structure. The decrease in the conductivity for the heavily doped Bi4Ti3O12 (BIT) must be associated to the unidentified crystal defects. For comparison, dielectric properties of crystalline BIT film were also investigated

  20. Noncontact Dielectric Friction

    OpenAIRE

    Kuehn, Seppe; Marohn, John A.; Loring, Roger F.

    2006-01-01

    Dielectric fluctuations are shown to be the dominant source of noncontact friction in high-sensitivity scanning probe microscopy of dielectric materials. Recent measurements have directly determined the friction acting on custom-fabricated single-crystal silicon cantilevers whose capacitively charged tips are located 3–200 nm above thin films of poly(methyl methacrylate), poly(vinyl acetate), and polystyrene. Differences in measured friction among these polymers are explained here by relating...

  1. Black silicon: substrate for laser 3D micro/nano-polymerization.

    Science.gov (United States)

    Žukauskas, Albertas; Malinauskas, Mangirdas; Kadys, Arūnas; Gervinskas, Gediminas; Seniutinas, Gediminas; Kandasamy, Sasikaran; Juodkazis, Saulius

    2013-03-25

    We demonstrate that black silicon (b-Si) made by dry plasma etching is a promising substrate for laser three-dimensional (3D) micro/nano-polymerization. High aspect ratio Si-needles, working as sacrificial support structures, have flexibility required to relax interface stresses between substrate and the polymerized micro-/nano- objects. Surface of b-Si can be made electrically conductive by metal deposition and, at the same time, can preserve low optical reflectivity beneficial for polymerization by direct laser writing. 3D laser polymerization usually performed at the irradiation conditions close to the dielectric breakdown is possible on non-reflective and not metallic surfaces. Here we show that low reflectivity and high metallic conductivity are not counter- exclusive properties for laser polymerization. Electrical conductivity of substrate and its permeability in liquids are promising for bio- and electroplating applications. PMID:23546073

  2. Pattern formation in dielectric barrier discharges with different dielectric materials

    International Nuclear Information System (INIS)

    The influence of dielectric material on the bifurcation and spatiotemporal dynamics of the patterns in dielectric barrier discharge in argon/air at atmospheric pressure is studied. It is found that pattern bifurcation sequences are different with different dielectric materials. The spatiotemporal dynamics of the hexagonal pattern in dielectric barrier discharge depends on the dielectric material. The hexagon pattern with glass dielectric is an interleaving of two rectangular sublattices appearing at different moments. The hexagon pattern with quartz dielectric is composed of one set of hexagonal lattice discharging twice in one half cycle of the applied voltage, one is at the rising edge and the other at the falling edge. It results in that the accumulation of wall charges in individual microdischarges in a hexagon pattern with quartz dielectric is greater than that with glass dielectric, which is in agreement with the electron density measurement by Stark broadening of Ar I 696.54 nm.

  3. Temperature dependence of the dielectric constant of acrylic dielectric elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Junjie; Chen, Hualing; Li, Bo; Chang, Longfei [Xi' an Jiaotong University, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an (China); Xi' an Jiaotong University, School of Mechanical Engineering, Xi' an (China)

    2013-02-15

    The dielectric constant is an essential electrical parameter to the achievable voltage-induced deformation of the dielectric elastomer. This paper primarily focuses on the temperature dependence of the dielectric constant (within the range of 173 K to 373 K) for the most widely used acrylic dielectric elastomer (VHB 4910). First the dielectric constant was investigated experimentally with the broadband dielectric spectrometer (BDS). Results showed that the dielectric constant first increased with temperature up to a peak value and then dropped to a relative small value. Then by analyzing the fitted curves, the Cole-Cole dispersion equation was found better to characterize the rising process before the peak values than the Debye dispersion equation, while the decrease process afterward can be well described by the simple Debye model. Finally, a mathematical model of dielectric constant of VHB 4910 was obtained from the fitted results which can be used to further probe the electromechanical stability of the dielectric elastomers. (orig.)

  4. Anisotropic dielectric substrate as thin dielectric resonator

    Czech Academy of Sciences Publication Activity Database

    Bovtun, Viktor; Pashkov, V.; Kempa, Martin; Molchanov, V.; Kamba, Stanislav; Poplavko, Y.; Yakymenko, Y.

    Sevastopol: Weber Publishing, 2012 - (Yermolov, P.), s. 573-574 ISBN 978-966-335-370-8. [International Conference Microwave & Telecommunication Technology /22./. Sevastopol (UA), 10.09.2012-14.09.2012] R&D Projects: GA ČR GAP204/12/1163 Institutional research plan: CEZ:AV0Z10100520 Keywords : dielectric resonator * substrate * microwave Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.crimico.org/en/

  5. Induction of Polymerization of the Surface Nanostructures of the Electrodes by Electric Field

    OpenAIRE

    S.G. Еmelyanov; A.E. Kuz'ko; A.V. Kuz'ko; A.P. Kuzmenko; P.A. Belov

    2014-01-01

    The results of experimental studies of the interface of "dielectric liquid - nanostructured metal electrode" after electroconvection is presented. It is discovered the patterns of structuring of areas of polymerization showing disruption of the diffusion layer and the processes of charge injection from the tops of structures.

  6. Induction of Polymerization of the Surface Nanostructures of the Electrodes by Electric Field

    Directory of Open Access Journals (Sweden)

    S.G. Еmelyanov

    2014-07-01

    Full Text Available The results of experimental studies of the interface of "dielectric liquid - nanostructured metal electrode" after electroconvection is presented. It is discovered the patterns of structuring of areas of polymerization showing disruption of the diffusion layer and the processes of charge injection from the tops of structures.

  7. POLYMERIC SURFACTANT STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    P.M. Saville; J.W. White

    2001-01-01

    Polymeric surfactants are amongst the most widespread of all polymers. In nature, proteins and polysaccharides cause self organization as a result of this surfactancy; in industry, polymeric surfactants play key roles in the food, explosives and surface coatings sectors. The generation of useful nano- and micro-structures in films and emulsions as a result of polymer amphiphilicity and the application of mechanical stress is discussed. The use of X-ray and neutron small angle scattering and reflectivity to measure these structures and their dynamic properties will be described. New results on linear and dendritic polymer surfactants are presented.

  8. Inflation of a Polymeric Menbrane

    DEFF Research Database (Denmark)

    Kristensen, Susanne B.; Larsen, Johannes R.; Hassager, Ole

    1998-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane.......We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane....

  9. Variable Effect during Polymerization

    Science.gov (United States)

    Lunsford, S. K.

    2005-01-01

    An experiment performing the polymerization of 3-methylthiophene(P-3MT) onto the conditions for the selective electrode to determine the catechol by using cyclic voltammetry was performed. The P-3MT formed under optimized conditions improved electrochemical reversibility, selectivity and reproducibility for the detection of the catechol.

  10. Dielectric behavior of Silica/Poly(dimethylsiloxane) nanocomposites. nano size effects

    International Nuclear Information System (INIS)

    The enhancement of properties of elastomeric composite materials is very much dependent on the size and the surface modification of the reinforcing filler inclusions. It is well accepted that the reinforcement effects are primarily due to molecular interactions of the polymeric matrix and the filler inclusions and it involves both chemical and physical interactions. In the present study, we have incorporated silica nano fillers (Stober silica) into poly(dimethylsiloxane) (PDMS) elastomeric networks. The dielectric properties of the networks were investigated as a function of filler nano filler size, volume fraction, and surface treatment by hexamethyldisilazane. The broad-spectrum dielectric properties (in particular, the dielectric constant, the dielectric loss, and tan δ) were characterized. These properties were found to be dependent on the size of the nano inclusions; thus, the results clearly showed a nano size phenomenon that was a highlight of the present research. Certainly, that can be largely attributed to the high specific surface area of the nano fillers, which significantly leads to a pronounced increase in interfacial interactions. Also, and as would be expected, the dielectric properties of the polymeric networks filled with unmodified particles were different from those for the polymeric networks filled with surface-modified particles. Again, this is mainly attributed to changes in the surface properties. The expected dependence of properties of the nanocomposite networks on the nature of the filler and its concentration has thus been demonstrated.

  11. Dielectric behavior of Silica/Poly(dimethylsiloxane) nanocomposites. nano size effects

    Science.gov (United States)

    Ibrahim, I. A. M.; Zikry, A. A. F.; Sharaf, M. A.; Mark, J. E.; Jacob, K.; Jasiuk, I. M.; Tannenbaumn, R.

    2012-09-01

    The enhancement of properties of elastomeric composite materials is very much dependent on the size and the surface modification of the reinforcing filler inclusions. It is well accepted that the reinforcement effects are primarily due to molecular interactions of the polymeric matrix and the filler inclusions and it involves both chemical and physical interactions. In the present study, we have incorporated silica nano fillers (Stober silica) into poly(dimethylsiloxane) (PDMS) elastomeric networks. The dielectric properties of the networks were investigated as a function of filler nano filler size, volume fraction, and surface treatment by hexamethyldisilazane. The broad-spectrum dielectric properties (in particular, the dielectric constant, the dielectric loss, and tan δ) were characterized. These properties were found to be dependent on the size of the nano inclusions; thus, the results clearly showed a nano size phenomenon that was a highlight of the present research. Certainly, that can be largely attributed to the high specific surface area of the nano fillers, which significantly leads to a pronounced increase in interfacial interactions. Also, and as would be expected, the dielectric properties of the polymeric networks filled with unmodified particles were different from those for the polymeric networks filled with surface-modified particles. Again, this is mainly attributed to changes in the surface properties. The expected dependence of properties of the nanocomposite networks on the nature of the filler and its concentration has thus been demonstrated.

  12. Polymeric synthesis of lead magnesium niobate powders

    International Nuclear Information System (INIS)

    This paper describes the polymeric synthesis of Pb3MgNb2O9-based dielectric powders. The results show that single-phase powders of about 50 nm crystalline size can be prepared at temperatures as low as 5000C. This preparation technique is based on having the individual cations complexed in separate weak organic acid solutions. The individual solutions are gravimetrically analyzed for the respective cation concentration to a precision of 10 to 100 ppm. In this way, it is possible to precisely control all of the cation concentrations, and to mix the ions on an atomic scale in the liquid state. There is no precipitation in the mixed solution, as it is evaporated to the rigid polymeric states in the form of a uniformly colored transparent glass. This glass is calcined to yield powders which are both homogeneous and single phase, with well-controlled cation stoichiometry. The synthesis process is described, along with some resulting electrical, microstructural, and crystallographic characteristics which were obtained for sintered capacitors made with powders derived from this synthesis

  13. Synthesis, characterization and dielectric properties of polynorbornadiene–clay nanocomposites by ROMP using intercalated Ruthenium catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Yalçınkaya, Esra Evrim, E-mail: esra.evrim.saka@ege.edu.tr; Balcan, Mehmet; Güler, Çetin

    2013-12-16

    Polynorbornadiene clay nanocomposites were prepared for the first time by the ring opening metathesis polymerization (ROMP) using modified montmorillonite and polynorbornadiene the latter of which is used commonly in electric–electronic industry. The Na–MMT clay was modified by a quaternary ammonium salt containing Ruthenium complex as a suitable catalyst and intercalant as well. The norbornadiene monomers were polymerized within the modified montmorillonite layers by in-situ polymerization method in different clay loading degrees. Intercalation ability of the Ru catalyst and partially exfoliated nanocomposite structure were proved by powder X-ray Diffraction (XRD) Spectroscopy and Transmission Electron Microscopy (TEM) methods. The nanocomposite materials with high thermal degradation temperature and low dielectric constant compared to the pure polynorbornadiene were obtained. The dielectric constants decreased with the increase of the clay content. - Highlights: • Polynorbornadiene–clay nanocomposites were prepared for the first time. • Ruthenium complex was assigned as both suitable catalyst and intercalant. • The norbornadiene was polymerized by in-situ polymerization method. • Exfoliation/intercalation structures were found to be related with loading degree. • PNBD–MMT nanocomposites had a higher thermal degradation temperature and lower dielectric constant.

  14. Synthesis, characterization and dielectric properties of polynorbornadiene–clay nanocomposites by ROMP using intercalated Ruthenium catalyst

    International Nuclear Information System (INIS)

    Polynorbornadiene clay nanocomposites were prepared for the first time by the ring opening metathesis polymerization (ROMP) using modified montmorillonite and polynorbornadiene the latter of which is used commonly in electric–electronic industry. The Na–MMT clay was modified by a quaternary ammonium salt containing Ruthenium complex as a suitable catalyst and intercalant as well. The norbornadiene monomers were polymerized within the modified montmorillonite layers by in-situ polymerization method in different clay loading degrees. Intercalation ability of the Ru catalyst and partially exfoliated nanocomposite structure were proved by powder X-ray Diffraction (XRD) Spectroscopy and Transmission Electron Microscopy (TEM) methods. The nanocomposite materials with high thermal degradation temperature and low dielectric constant compared to the pure polynorbornadiene were obtained. The dielectric constants decreased with the increase of the clay content. - Highlights: • Polynorbornadiene–clay nanocomposites were prepared for the first time. • Ruthenium complex was assigned as both suitable catalyst and intercalant. • The norbornadiene was polymerized by in-situ polymerization method. • Exfoliation/intercalation structures were found to be related with loading degree. • PNBD–MMT nanocomposites had a higher thermal degradation temperature and lower dielectric constant

  15. Dielectric Constant of Suspensions

    Science.gov (United States)

    Mendelson, Kenneth S.; Ackmann, James J.

    1997-03-01

    We have used a finite element method to calculate the dielectric constant of a cubic array of spheres. Extensive calculations support preliminary conclusions reported previously (K. Mendelson and J. Ackmann, Bull. Am. Phys. Soc. 41), 657 (1996).. At frequencies below 100 kHz the real part of the dielectric constant (ɛ') shows oscillations as a function of the volume fraction of suspension. These oscillations disappear at low conductivities of the suspending fluid. Measurements of the dielectric constant (J. Ackmann, et al., Ann. Biomed. Eng. 24), 58 (1996). (H. Fricke and H. Curtis, J. Phys. Chem. 41), 729 (1937). are not sufficiently sensitive to show oscillations but appear to be consistent with the theoretical results.

  16. PREFACE: Dielectrics 2013

    Science.gov (United States)

    Hadjiloucas, Sillas; Blackburn, John

    2013-11-01

    This volume records the 42nd Dielectrics Group Proceedings of the Dielectrics Conference that took place at the University of Reading UK from 10-12 April 2013. The meeting is part of the biennial Dielectrics series of the Dielectrics Group, and formerly Dielectrics Society, and is organised by the Institute of Physics. The conference proceedings showcase some of the diversity and activity of the Dielectrics community worldwide, and bring together contributions from academics and industrial researchers with a diverse background and experiences from the Physics, Chemistry and Engineering communities. It is interesting to note some continuing themes such as Insulation/HV Materials, Dielectric Spectroscopy, Dielectric Measurement Techniques and Ferroelectric materials have a growing importance across a range of technologically important areas from the Energy sector to Materials research, Semiconductor and Electronics industries, and Metrology. We would like to thank all of our colleagues and friends in the Dielectrics community who have supported this event by contributing manuscripts and participating in the event. The conference has provided excellent networking opportunities for all delegates. Our thanks go also to our theme chairs: Dr Stephen Dodd (University of Leicester) on Insulation/HV Materials, Professor Darryl Almond (University of Bath) on Dielectric Spectroscopy, Dr John Blackburn (NPL) on Dielectric Measurement Techniques and Professor Anthony R West (University of Sheffield) on Ferroelectric Materials. We would also like to thank the other members of the Technical Programme Committee for their support, and refereeing the submitted manuscripts. Our community would also like to wish a full recovery to our plenary speaker Prof John Fothergill (City University London) who was unexpectedly unable to give his talk as well as thank Professor Alun Vaughan for stepping in and giving an excellent plenary lecture in his place at such very short notice. We are also

  17. Development of dielectric microcalorimeter

    International Nuclear Information System (INIS)

    A prototype dielectric microcalorimeter was fabricated from 0.99SrTiO3-0.01SrTa2O6, a dielectric material. To estimate the operation performance of the microcalorimeter, a simple evaluation model is introduced by employing the block diagram formalism. Pulse height and fall time constant of the detection signal are analyzed as a function of the thermal conductance of the heat link. The dielectric microcalorimeter maintained at 100 mK was irradiated by 5.5 MeV α-particles emitting from an 241Am source. Responsivity was found to be 2.7x10-19 C/eV. (author)

  18. Dielectric behaviour of polycarbonate

    Science.gov (United States)

    El-Shabasy, M.; Riad, A. S.

    1996-05-01

    The dielectric constant and the dielectric loss of polycarbonate are investigated in the frequency range 30-10 5 Hz and at temperature from 297 to 365 K. The frequency dependence of the impedance spectra plotted in the complex plane shows semicircles. The system could be represented by an equivalent circuit of a bulk resistance in series with a parallel surface resistance-capacitance combination. The Cole-Cole diagrams have been used to determine the molecular relaxation time τ. The temperature dependence of τ is expressed by a thermally activated process. Analysis of the AC conductivity reveals semiconducting features based predominantly on a hopping mechanism.

  19. Multilayer dielectric diffraction gratings

    Science.gov (United States)

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  20. Dielectric measurements on HTS insulation systems for electric power equipment

    International Nuclear Information System (INIS)

    Since the development of flexible high temperature superconducting multifilament wires superconductive coils were constructed for the application in electric power equipment. The dielectric behaviour of conventional technology is well known, but this experience can only be partially applied to superconducting insulation systems. Some prototypes of cables, power and traction transformers and current limiters were built, but there is not sufficient knowledge about optimum dielectric structures and ageing. This paper gives a view to the criterions for liquid nitrogen as coolant and insulating medium of low temperature insulating systems for electric power equipment and shows the results of dielectric measurements tested with different structures

  1. Frontal Polymerization in Microgravity

    Science.gov (United States)

    Pojman, John A.

    1999-01-01

    Frontal polymerization systems, with their inherent large thermal and compositional gradients, are greatly affected by buoyancy-driven convection. Sounding rocket experiments allowed the preparation of benchmark materials and demonstrated that methods to suppress the Rayleigh-Taylor instability in ground-based research did not significantly affect the molecular weight of the polymer. Experiments under weightlessness show clearly that bubbles produced during the reaction interact very differently than under 1 g.

  2. Polymeric bicontinuous microemulsions

    DEFF Research Database (Denmark)

    Bates, F.S.; Maurer, W.W.; Lipic, P.M.; Hillmyer, M.A.; Almdal, K.; Mortensen, K.; Fredrickson, G.H.; Lodge, T.P.

    1997-01-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in nurtures containing a model diblock copolymer and two homopolymers. Alt....... Although we attribute development of this equilibrium morphology to the effects of fluctuations, mean-field theory provides a quantitative strategy for preparing the bicontinuous state at blend compositions near an isotropic Lifshitz point....

  3. Polymeric bicontinuous microemulsions

    DEFF Research Database (Denmark)

    Bates, F.S.; Maurer, W.W.; Lipic, P.M.;

    1997-01-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in nurtures containing a model diblock copolymer and two homopolymers....... Although we attribute development of this equilibrium morphology to the effects of fluctuations, mean-field theory provides a quantitative strategy for preparing the bicontinuous state at blend compositions near an isotropic Lifshitz point....

  4. Polymeric Bicontinuous Microemulsions

    Science.gov (United States)

    Bates, Frank S.; Maurer, Wayne W.; Lipic, Paul M.; Hillmyer, Marc A.; Almdal, Kristoffer; Mortensen, Kell; Fredrickson, Glenn H.; Lodge, Timothy P.

    1997-08-01

    High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in mixtures containing a model diblock copolymer and two homopolymers. Although we attribute development of this equilibrium morphology to the effects of fluctuations, mean-field theory provides a quantitative strategy for preparing the bicontinuous state at blend compositions near an isotropic Lifshitz point.

  5. Dielectric behaviour of nano-crystalline spinel Ni0.2Ca0.8Fe2O4 and their nano-composite with polypyrrole

    Indian Academy of Sciences (India)

    Arun S Prasad; S N Dolia; P Predeep

    2011-12-01

    The spinel ferrite nano-particles of chemical composition Ni0.2Ca0.8Fe2O4 have been prepared by sol–gel method. Subsequently, the nanoparticles are encapsulated with the intrinsically conducting polymer shell of polypyrrole. The X-ray diffraction patterns confirm the single phase cubic spinel structure of the materials. To understand the dielectric properties of the materials, frequency-dependent dielectric measurement has been performed at 300 K in the range of 100 mHz to 2 MHz. On polymerization, both the dielectric strength as well the dielectric loss is significantly increased. Also, the dielectric conductivity, which arises from the electron hopping mechanism, is considerably increased on polymerization.

  6. Plasma polymerization of an ethylene-nitrogen gas mixture

    Science.gov (United States)

    Hudis, M.; Wydeven, T.

    1975-01-01

    A procedure has been developed whereby nitrogen can be incorporated into an organic film from an ethylene-nitrogen gas mixture using an internal electrode capacitively coupled radio frequency reactor. The presence of nitrogen has been shown directly by infrared transmittance spectra and electron spectroscopic chemical analysis data, and further indirect evidence was provided by dielectric measurements and by the reverse osmosis properties of the film. Preparation of a nitrogen containing film did not require vapor from an organic nitrogen containing liquid monomer. Some control over the bonding and stoichiometry of the polymer film was provided by the added degree of freedom of the nitrogen partial pressure in the gas mixture. This new parameter strongly affected the dielectric properties of the plasma polymerized film and could affect the reverse osmosis behavior.

  7. Dynamic space charge behaviour in polymeric DC cables

    DEFF Research Database (Denmark)

    Rasmussen, Claus Nygaard; Holbøll, Joachim; Henriksen, Mogens

    2002-01-01

    The use of extruded insulation for DC cables involves a risk of local electric field enhancement, caused by a space charge build-up within the dielectric. In this work, the theory of charge generation and transport in polymers is applied in a numerical computer model in order to predict the forma...... dielectric. Results obtained using this model-based framework are compared to measurement results obtained from Laser Induced Pressure Pulse (LIPP) space charge measurements as well as conductivity measurements on selected cable type samples.......The use of extruded insulation for DC cables involves a risk of local electric field enhancement, caused by a space charge build-up within the dielectric. In this work, the theory of charge generation and transport in polymers is applied in a numerical computer model in order to predict the...... formation and transport of space charges in a polymeric dielectric. The model incorporates the processes of field assisted electron-hole pair generation from impurity atoms, trapping and charge injection at the electrodes. Its aim has been to study the field- and temperature dependent dynamic behaviour of a...

  8. Packaging based on polymeric materials

    OpenAIRE

    Jovanović Slobodan M.; Živković Predrag M.; Stoiljković Dragoslav M.

    2005-01-01

    In the past two years the consumption of common in the developed countries world wide (high tonnage) polymers for packaging has approached a value of 50 wt.%. In the same period more than 50% of the packaging units on the world market were made of polymeric materials despite the fact that polymeric materials present 17 wt.% of all packaging materials. The basic properties of polymeric materials and their environmental and economical advantages, providing them such a position among packaging m...

  9. Antenna with Dielectric Having Geometric Patterns

    Science.gov (United States)

    Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)

    2013-01-01

    An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.

  10. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites

    Directory of Open Access Journals (Sweden)

    Liu Tian

    2011-01-01

    Full Text Available Abstract We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated-reinforced high-density polyethylene (HDPE composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  11. Sustainable polymerizations in recoverable microemulsions.

    Science.gov (United States)

    Chen, Zhenzhen; Yan, Feng; Qiu, Lihua; Lu, Jianmei; Zhou, Yinxia; Chen, Jiaxin; Tang, Yishan; Texter, John

    2010-03-16

    Free radical and atom-transfer radical polymerizations were conducted in monomer/ionic liquid microemulsions. After the polymerization and isolation of the resultant polymers, the mixture of the catalyst and ionic liquids (surfactant and continuous phase) can be recovered and reused, thereby dramatically improving the environmental sustainability of such chemical processing. The addition of monomer to recovered ionic liquid mixtures regenerates transparent, stable microemulsions that are ready for the next polymerization cycle upon addition of initiator. The method combines the advantages of IL recycling and microemulsion polymerization and minimizes environmental disposable effects from surfactants and heavy metal ions. PMID:20170175

  12. Polymerization Evaluation by Spectrophotometric Measurements.

    Science.gov (United States)

    Dunach, Jaume

    1985-01-01

    Discusses polymerization evaluation by spectrophotometric measurements by considering: (1) association degrees and molar absorptivities; (2) association degrees and equilibrium constants; and (3) absorbance and equilibrium constants. (JN)

  13. Radiation polymerization of unsaturated polyester

    International Nuclear Information System (INIS)

    Radiation polymerization of unsaturated polyester has been studied, either under electron beams or gamma rays. Addition of reducing agents of dyes will reduce the rate of polymerization. Rate of polymerization is proportional to 1sup(a), where the value of ''a'' is dependent on the composition of the monomer and polymer (1= dose rate). Infrared examinations indicated that for higher dose of irradiation, 8,5 Mrad in the case of unsaturated polyester STRATYL under electron beams, either polymerization or degradation of ester groups can take place. (author)

  14. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  15. Living olefin polymerization processes

    Science.gov (United States)

    Schrock, Richard R.; Baumann, Robert

    1999-01-01

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  16. The Major and Minor Relaxations in Polymeric Ni-Zn-Cu-Co Complex Nanocomposite Systems

    Science.gov (United States)

    Akbulut, S.; şentürk, E.; Köseoğlu, Y.

    2015-02-01

    Nanocrystalline polymeric complex (Ni0.5Zn0.4Cu0.1) ferrite substituted cobalt (Co) ferrite system has been synthesized by chemical co precipitation method. The dielectric properties of polymeric spinel ferrite system (Ni0.5Zn0.4Cu0.1Fe2O4)x (CoFe2O4)1-x have been investigated. Some of the dielectric parameters such as dielectric permittivity ɛ' and loss tangent (tan δ) were studied as a function of frequency in the range 1 Hz-1 MHz and of temperature in the range 230-410 K. Excessive dependency of dielectric properties on frequency and temperature with the presence of two relaxation mechanisms, which are called as major and minor, have been observed. From Argand diagram analysis α and Δɛ values for these two kinds of relaxation curves have been determined for all the samples in the measured temperatures. The reported dielectric properties are thought to be meaningful for future applications.

  17. All-dielectric metamaterials

    Science.gov (United States)

    Jahani, Saman; Jacob, Zubin

    2016-01-01

    The ideal material for nanophotonic applications will have a large refractive index at optical frequencies, respond to both the electric and magnetic fields of light, support large optical chirality and anisotropy, confine and guide light at the nanoscale, and be able to modify the phase and amplitude of incoming radiation in a fraction of a wavelength. Artificial electromagnetic media, or metamaterials, based on metallic or polar dielectric nanostructures can provide many of these properties by coupling light to free electrons (plasmons) or phonons (phonon polaritons), respectively, but at the inevitable cost of significant energy dissipation and reduced device efficiency. Recently, however, there has been a shift in the approach to nanophotonics. Low-loss electromagnetic responses covering all four quadrants of possible permittivities and permeabilities have been achieved using completely transparent and high-refractive-index dielectric building blocks. Moreover, an emerging class of all-dielectric metamaterials consisting of anisotropic crystals has been shown to support large refractive index contrast between orthogonal polarizations of light. These advances have revived the exciting prospect of integrating exotic electromagnetic effects in practical photonic devices, to achieve, for example, ultrathin and efficient optical elements, and realize the long-standing goal of subdiffraction confinement and guiding of light without metals. In this Review, we present a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index metamaterials and anisotropic metamaterials. Finally, we discuss current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics, as well as biomimetic metasurfaces.

  18. Dielectric Wakefield Researches

    International Nuclear Information System (INIS)

    Excitation of wakefield in cylindrical dielectric waveguide/resonator by a sequence of relativistic electron bunches was investigated using an electron linac 'Almaz-2' (4.5 MeV, 6·103 bunches of duration 60 ps and charge 0.32 nC each). Energy spectrum of electrons, radial topography and longitudinal distribution of wakefield, and total energy of excited wakefield were measured by means of magnetic analyzer, high frequency probe, and a sensitive calorimeter

  19. All-dielectric metamaterials.

    Science.gov (United States)

    Jahani, Saman; Jacob, Zubin

    2016-01-01

    The ideal material for nanophotonic applications will have a large refractive index at optical frequencies, respond to both the electric and magnetic fields of light, support large optical chirality and anisotropy, confine and guide light at the nanoscale, and be able to modify the phase and amplitude of incoming radiation in a fraction of a wavelength. Artificial electromagnetic media, or metamaterials, based on metallic or polar dielectric nanostructures can provide many of these properties by coupling light to free electrons (plasmons) or phonons (phonon polaritons), respectively, but at the inevitable cost of significant energy dissipation and reduced device efficiency. Recently, however, there has been a shift in the approach to nanophotonics. Low-loss electromagnetic responses covering all four quadrants of possible permittivities and permeabilities have been achieved using completely transparent and high-refractive-index dielectric building blocks. Moreover, an emerging class of all-dielectric metamaterials consisting of anisotropic crystals has been shown to support large refractive index contrast between orthogonal polarizations of light. These advances have revived the exciting prospect of integrating exotic electromagnetic effects in practical photonic devices, to achieve, for example, ultrathin and efficient optical elements, and realize the long-standing goal of subdiffraction confinement and guiding of light without metals. In this Review, we present a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index metamaterials and anisotropic metamaterials. Finally, we discuss current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics, as well as biomimetic metasurfaces. PMID:26740041

  20. Efeito do envelhecimento de catalisadores Ziegler-Natta à base de neodímio sobre a polimerização de 2-metil, 1,3-butadieno Effect of aging time of Ziegler-Natta catalysts based on neodimium for 2-methyl, 1,3-butadiene polymerization

    Directory of Open Access Journals (Sweden)

    André Luiz Carneiro Simões

    2013-01-01

    Full Text Available O objetivo deste trabalho foi estudar o efeito do tempo de envelhecimento natural do sistema catalítico versatato de neodímio/hidreto de di-isobutilalumínio/cloreto de t-butila sobre a polimerização de 2-metil, 1,3-butadieno (isopreno. Foram avaliadas a atividade catalítica e conversão, além da massa molar, distribuição de massa molar e microestrutura dos polímeros. Foi objetivo estudar também as características micro e macroestruturais do poli-1,4-cis-isopreno ao longo da polimerização. Os catalisadores envelhecidos apresentaram tempos mais curtos ao longo da polimerização e uma conversão mais alta em relação ao catalisador não envelhecido. Estes resultados em conjunto com a menor atividade catalítica nos catalisadores envelhecidos sugerem a provável desativação de alguns sítios ativos mais sensíveis. Não foi observada influência do envelhecimento do catalisador sobre a microestrutura do polímero. Houve também aumento da massa molar e estreitamento na polidispersão conforme o aumento da conversão.The goal of this work was to study the aging effects of the catalytic system neodymium versatate/diisobutylaluminium hydride/t-butyl chloride on 2-methyl, 1.3-butadiene (isoprene polymerization. The catalytic activity, conversion and polymer characteristics (molar mass, molar mass distribution and microstructure were evaluated. The macro and microstructural characteristics of poly-1.4-cis-isoprene along the polymerization were also studied. The aged catalysts have shorter times along the polymerization and a higher conversion than the non-aged catalyst. Together with the lower catalytic activity for aged catalysts, these results point to possible disabling of the most sensitive active sites. Aging of the catalyst did not affect the polymer microstructure. As the conversion progressed, the molar mass increased with a narrowing in the molecular weight distribution.

  1. Dielectric lattice gauge theory

    International Nuclear Information System (INIS)

    Dielectric lattice gauge theory models are introduced. They involve variables PHI(b)epsilong that are attached to the links b = (x+esub(μ),x) of the lattice and take their values in the linear space g which consists of real linear combinations of matrices in the gauge group G. The polar decomposition PHI(b)=U(b)osub(μ)(x) specifies an ordinary lattice gauge field U(b) and a kind of dielectric field epsilonsub(ij)proportionalosub(i)osub(j)sup(*)deltasub(ij). A gauge invariant positive semidefinite kinetic term for the PHI-field is found, and it is shown how to incorporate Wilson fermions in a way which preserves Osterwalder Schrader positivity. Theories with G = SU(2) and without matter fields are studied in some detail. It is proved that confinement holds, in the sense that Wilson loop expectation values show an area law decay, if the Euclidean action has certain qualitative features which imply that PHI = 0 (i.e. dielectric field identical 0) is the unique maximum of the action. (orig.)

  2. EDITORIAL: Bio-dielectrics: theories, mechanisms and applications

    Science.gov (United States)

    Pethig, Ronald

    2007-01-01

    This special cluster in Journal of Physics D: Applied Physics comprises papers submitted by participants at the 2006 conference of the Institute of Physics Dielectrics Group, held at the University of Leicester during 10-12 April 2006. The conference focused on the interaction of non-ionizing electromagnetic (EM) fields with biological materials at all scales (tissues down to molecules) and at all frequencies. The use of dielectric techniques and theories in biological studies and in the pharmaceutical and biotechnology industries is increasing, and we hope that this conference helped to facilitate this trend and to further an understanding of the value of dielectric studies in biology—both in science and in applications in industry and medicine. An important policy of the Dielectrics Group is to promote the multidisciplinary nature of dielectric studies, and so we welcomed and received papers and posters from biologists, chemists, engineers, industrialists, medical professionals and physicists in the biotechnology and health care fields. The programme comprised 32 oral presentations, including the keynote opening address `Bio-dielectrics and bio-impedance' by Dr Ø G Martinson of the University of Oslo, and 7 papers given by invited speakers. 27 high-quality posters were also exhibited. The Mansel Davies Award, for the best presentation by a young researcher under the age of 30, was bestowed on Mr Sun Tao from the University of Southampton. His work, describing time domain analysis applied to dielectric spectroscopy of single cells, forms the subject matter of the first paper in this cluster. The remaining papers are presented in order of the session themes, namely Dielectric Spectroscopy and Techniques, Theory and Modelling, and Electrokinetics. On behalf of the Dielectrics Group, I thank the authors for their contributions, and the Institute of Physics for excellent administrative and editorial assistance.

  3. Dielectric relaxation and hydrogen diffusion in amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.C. (AT and T Bell Labs., Murray Hill, NJ (United States))

    1994-04-01

    Hydrogen diffusion is technologically critical to the processing of amorphous Si for solar cell applications. It is shown that this diffusion belongs to a broad class of dielectric relaxation mechanisms which were first studied by Kohlrausch in 1847. A microscopic theory of the Kohlrausch relaxation constant [beta][sub K] is also constructed. This theory explains the values of [beta] observed in many electronic, molecular and polymeric relaxation processes. It is based on two novel concepts: Wiener sausages, from statistical mechanics, and the magic wand, from axiomatic set theory

  4. Influência do envelhecimento de catalisadores Ziegler-Natta à base de neodímio sobre a polimerização de 1,3-butadieno Influence of ageing of neodymium based Ziegler-Natta catalyst on butadiene polymerization

    Directory of Open Access Journals (Sweden)

    Ivana L. Mello

    2007-03-01

    Full Text Available Catalisadores envelhecidos em diferentes tempos (0, 5, 15, 40, 80 e 160 dias e diferentes temperaturas (10, 25 e 40 °C foram testados na polimerização 1,4-cis do 1,3-butadieno. Avaliou-se a atividade catalítica bem como as características do polímero obtido (massa molecular e microestrutura. Os resultados encontrados mostraram que a variação nas condições de envelhecimento dos catalisadores não influenciou a microestrutura do polímero. O teor de unidades 1,4-cis permaneceu em torno de 98%, de unidades 1,4-trans em torno de 1,4% e de unidades vinílicas em 0,6%. Entretanto, reações utilizando os catalisadores envelhecidos por 40 dias forneceram polibutadieno com maior massa molecular do que os demais catalisadores. Verificou-se também, uma tendência de maiores conversões das polimerizações com os catalisadores envelhecidos a 25 °C.Catalysts aged for different time periods (0, 5, 15, 40, 80 and 160 days and different temperatures (10, 25 and 40 °C were tested in the cis-1,4 polymerization of 1,3-butadiene. The catalytic activity and polymer characteristics (molecular weight and microstructure were evaluated. The results showed that the catalyst ageing did not affect the polymer microstructure. The cis-1,4 content remained at 98%, trans-1,4 at 1,4% and vinyl units at 0,6%. However, the catalysts aged for 40 days produced polybutadienes with higher molecular weight. Also observed was a tendency to an increased polymerization conversion by the catalysts aged at 25 °C.

  5. Additive manufacturing of graded dielectrics

    International Nuclear Information System (INIS)

    A method for the fabrication of graded dielectrics within a structural composite is presented. This system employs an ultrasonic powder deposition head to print high dielectric powders onto a woven fabric composite substrate. It is shown how this system can integrate 3D variations of dielectric properties at millimeter resolution within a mechanically rugged substrate. To conclude, the system’s practical application is demonstrated with experimental results from a graded index lens. (paper)

  6. Polyaniline coated cellulose fiber / polyvinyl alcohol composites with high dielectric permittivity and low percolation threshold

    Directory of Open Access Journals (Sweden)

    V. P. Anju

    2016-01-01

    Full Text Available Cost effective, high performance dielectric composites based on polyvinyl alcohol, cellulose fibers and polyaniline were prepared and the dielectric properties were studied as a function of fiber content, fiber dimensions and polyaniline content over a frequency range of 40 Hz to 30 MHz. The short cellulose fibers were size-reduced to micro and nano levels prior to coating with polyaniline. Fiber surface was coated with Polyaniline (PANI by an in situ polymerization technique in aqueous medium. The composites were then prepared by solution casting method. Short cellulose fiber composites showed a dielectric constant (DEC of 2.3 x 105 at 40 Hz. For the micro- and nano- cellulose fiber composites the DEC was increased to 4.5 x 105 and 1.3 x 108, respectively. To gain insight into the inflection point of the dielectric data polynomial regression analysis was carried out. The loss tangent of all the composites remained at less than 1.5. Further, AC conductivity, real and imaginary electric moduli of all the composites were evaluated. PVA nanocomposite attained an AC conductivity of 3 S/m. These showed that by controlling the size of the fiber used, it was possible to tune the permittivity and dielectric loss to desired values over a wide range. These novel nanocomposites, combining high dielectric constant and low dielectric loss, can be effectively used in applications such as high-charge storage capacitors.

  7. Polyaniline coated cellulose fiber / polyvinyl alcohol composites with high dielectric permittivity and low percolation threshold

    Science.gov (United States)

    Anju, V. P.; Narayanankutty, Sunil K.

    2016-01-01

    Cost effective, high performance dielectric composites based on polyvinyl alcohol, cellulose fibers and polyaniline were prepared and the dielectric properties were studied as a function of fiber content, fiber dimensions and polyaniline content over a frequency range of 40 Hz to 30 MHz. The short cellulose fibers were size-reduced to micro and nano levels prior to coating with polyaniline. Fiber surface was coated with Polyaniline (PANI) by an in situ polymerization technique in aqueous medium. The composites were then prepared by solution casting method. Short cellulose fiber composites showed a dielectric constant (DEC) of 2.3 x 105 at 40 Hz. For the micro- and nano- cellulose fiber composites the DEC was increased to 4.5 x 105 and 1.3 x 108, respectively. To gain insight into the inflection point of the dielectric data polynomial regression analysis was carried out. The loss tangent of all the composites remained at less than 1.5. Further, AC conductivity, real and imaginary electric moduli of all the composites were evaluated. PVA nanocomposite attained an AC conductivity of 3 S/m. These showed that by controlling the size of the fiber used, it was possible to tune the permittivity and dielectric loss to desired values over a wide range. These novel nanocomposites, combining high dielectric constant and low dielectric loss, can be effectively used in applications such as high-charge storage capacitors.

  8. Dielectric properties of fly ash

    Indian Academy of Sciences (India)

    S C Raghavendra; R L Raibagkar; A B Kulkarni

    2002-02-01

    This paper reports the dielectric properties of fly ash. The dielectric measurements were performed as a function of frequency and temperature. The sample of fly ash shows almost similar behaviour in the frequency and temperature range studied. The large value of dielectric constant in the typical frequency range is because of orientation polarization and tight binding force between the ions or atoms in the fly ash. The sample of fly ash is of great scientific and technological interest because of its high value of dielectric constant (104).

  9. Plasma polymerization by Softplasma

    DEFF Research Database (Denmark)

    Jiang, J.; Wu, Zhenning; Benter, Maike;

    2008-01-01

    In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode...... reactive splvent (as shown in Figure 1). 1] H. Biederman, in Plasma Polymer Films. (ed.) H. Biederman. Imperial College Press, Singapore, 13-24 ~OO~· '. , [2] R. d'Agostino et.a!. in Plasma Depd~itiqn, 'Treatment, and Etching ofPolymers. (ed.) R. d'Agostino, Academic Press, U.S. (1990). [3] F. F. Shi....... Recent advances in polymer thin films prepared by plasma polymerization synthesis, structural characterization, properties and applications. Surface and Coating Technology 82, 1 (1996). [4] B. Winther-Jensen. WOO0235895A2. A method and apparatus for excitation of a plasma, (2002). [5]. K. Glejbol. EP...

  10. Boron nitride as two dimensional dielectric: Reliability and dielectric breakdown

    International Nuclear Information System (INIS)

    Boron Nitride (BN) is a two dimensional insulator with excellent chemical, thermal, mechanical, and optical properties, which make it especially attractive for logic device applications. Nevertheless, its insulating properties and reliability as a dielectric material have never been analyzed in-depth. Here, we present the first thorough characterization of BN as dielectric film using nanoscale and device level experiments complementing with theoretical study. Our results reveal that BN is extremely stable against voltage stress, and it does not show the reliability problems related to conventional dielectrics like HfO2, such as charge trapping and detrapping, stress induced leakage current, and untimely dielectric breakdown. Moreover, we observe a unique layer-by-layer dielectric breakdown, both at the nanoscale and device level. These findings may be of interest for many materials scientists and could open a new pathway towards two dimensional logic device applications

  11. Boron nitride as two dimensional dielectric: Reliability and dielectric breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yanfeng; Pan, Chengbin; Hui, Fei; Shi, Yuanyuan; Lanza, Mario, E-mail: mlanza@suda.edu.cn [Institute of Functional Nano and Soft Materials, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123 (China); Zhang, Meiyun; Long, Shibing [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Lian, Xiaojuan; Miao, Feng [National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Larcher, Luca [DISMI, Università di Modena e Reggio Emilia, 42122 Reggio Emilia (Italy); Wu, Ernest [IBM Research Division, Essex Junction, Vermont 05452 (United States)

    2016-01-04

    Boron Nitride (BN) is a two dimensional insulator with excellent chemical, thermal, mechanical, and optical properties, which make it especially attractive for logic device applications. Nevertheless, its insulating properties and reliability as a dielectric material have never been analyzed in-depth. Here, we present the first thorough characterization of BN as dielectric film using nanoscale and device level experiments complementing with theoretical study. Our results reveal that BN is extremely stable against voltage stress, and it does not show the reliability problems related to conventional dielectrics like HfO{sub 2}, such as charge trapping and detrapping, stress induced leakage current, and untimely dielectric breakdown. Moreover, we observe a unique layer-by-layer dielectric breakdown, both at the nanoscale and device level. These findings may be of interest for many materials scientists and could open a new pathway towards two dimensional logic device applications.

  12. Preparation of ferroelectric (Pb, Sr)TiO3/polyethylene nanocomposites and their dielectric properties

    International Nuclear Information System (INIS)

    Ziegler-Natta catalysts were supported on nanosized ferroelectric (Pb, Sr)TiO3 (PST) powders and then (Pb, Sr)TiO3/polyethylene (PST/PE) nanocomposites were prepared by in situ polymerization. PST/PE nanocomposites with different volume fractions of PST were obtained by changing the polymerization time. The dispersion and element distribution of PST powders in the PST/PE nanocomposite were investigated. The results indicated that PST homogeneously dispersed in the PE matrix and PST/PE nanocomposite was formed. Moreover, the dielectric constant of PST/PE appeared to have a strong concentration dependence. (author)

  13. Radiation electric ocnductivity of polymeric materials

    International Nuclear Information System (INIS)

    Investigated was the radiation electric conductivity of some polymeric materials (polyethylene terephthalate, polystyrene, polyimeide, fluorolon F-4) under the effect of gamma radiation. Experiments were carried out at room temperature in vacuum on 11-60 μm thick films of two types, differing in the method of silver electrode spraying. It is shown that at radiation dose rate of 100 R/s electric conductivity of films at cathodic electrode spraying is greater than their electric conductivity at the thermal spraying method. A long aging of investigated materials in strong electric fields may change essentially the value of radiation electric conductivity and the character of its dependence on radiation dose rate

  14. Polymerization in emulsion microdroplet reactors

    Science.gov (United States)

    Carroll, Nick J.

    The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to

  15. Dielectric laser accelerators

    Science.gov (United States)

    England, R. Joel; Noble, Robert J.; Bane, Karl; Dowell, David H.; Ng, Cho-Kuen; Spencer, James E.; Tantawi, Sami; Wu, Ziran; Byer, Robert L.; Peralta, Edgar; Soong, Ken; Chang, Chia-Ming; Montazeri, Behnam; Wolf, Stephen J.; Cowan, Benjamin; Dawson, Jay; Gai, Wei; Hommelhoff, Peter; Huang, Yen-Chieh; Jing, Chunguang; McGuinness, Christopher; Palmer, Robert B.; Naranjo, Brian; Rosenzweig, James; Travish, Gil; Mizrahi, Amit; Schachter, Levi; Sears, Christopher; Werner, Gregory R.; Yoder, Rodney B.

    2014-10-01

    The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. The physics and technology of this approach is reviewed, which is referred to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV /m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Because of the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high-energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

  16. Dielectric Actuation of Polymers

    Science.gov (United States)

    Niu, Xiaofan

    Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy densities, high coupling efficiency, quiet operation, and light weight. One focus of this dissertation is on the design of DE materials with high performance and easy processing. UV radiation curing of reactive species is studied as a generic synthesis methodology to provide a platform for material scientists to customize their own DE materials. Oligomers/monomers, crosslinkers, and other additives are mixed and cured at appropriate ratios to control the stress-strain response, suppress electromechanical instability of the resulting polymers, and provide stable actuation strains larger than 100% and energy densities higher than 1 J/g. The processing is largely simplified in the new material system by removal of the prestretching step. Multilayer stack actuators with 11% linear strain are demonstrated in a procedure fully compatible with industrial production. A multifunctional DE derivative material, bistable electroactive polymer (BSEP), is invented enabling repeatable rigid-to-rigid deformation without bulky external structures. Bistable actuation allows the polymer actuator to have two distinct states that can support external load without device failure. Plasticizers are used to lower the glass transition temperature to 45 °C. Interpenetrating polymer network structure is established inside the BSEP to suppress electromechanical instability, providing a breakdown field of 194 MV/m and a stable bistable strain as large as 228% with a 97% strain fixity. The application of BSEP

  17. High-Voltage Insulation Organic-Inorganic Nanocomposites by Plasma Polymerization

    Directory of Open Access Journals (Sweden)

    Wei Yan

    2014-01-01

    Full Text Available In organic-inorganic nanocomposites, interfacial regions are primarily influenced by the dispersion uniformity of nanoparticles and the strength of interfacial bonds between the nanoparticles and the polymer matrix. The insulating performance of organic-inorganic dielectric nanocomposites is highly influenced by the characteristics of interfacial regions. In this study, we prepare polyethylene oxide (PEO-like functional layers on silica nanoparticles through plasma polymerization. Epoxy resin/silica nanocomposites are subsequently synthesized with these plasma-polymerized nanoparticles. It is found that plasma at a low power (i.e., 10 W can significantly increase the concentration of C–O bonds on the surface of silica nanoparticles. This plasma polymerized thin layer can not only improve the dispersion uniformity by increasing the hydrophilicity of the nanoparticles, but also provide anchoring sites to enable the formation of covalent bonds between the organic and inorganic phases. Furthermore, electrical tests reveal improved electrical treeing resistance and decreased dielectric constant of the synthesized nanocomposites, while the dielectric loss of the nanocomposites remains unchanged as compared to the pure epoxy resin.

  18. CoCl2 reinforced polymeric nanocomposites of conjugated polymer (polyaniline) and its conductive properties

    Indian Academy of Sciences (India)

    M Majhi; R B Choudhary; P Maji

    2015-09-01

    Polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline using ammonium persulphate as an oxidant in acidic aqueous medium. Cobalt chloride hexahydrate (CoCl2⋅6H2O)-doped PANI composite was synthesized by in-situ oxidative polymerization process by using various concentrations of CoCl2. Its chemical, structural and morphological properties were examined by X-ray diffraction, energydispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and field-emission scanning electron microscopy techniques. These results confirmed the successful formation of PANI and CoCl2-doped PANI nanocomposites. The morphology of CoCl2-doped PANI nanocomposite was found to be spherical in nature. The dielectric properties were examined using LCR-HITESTER in the frequency range 50 Hz–5 MHz. The optical properties were examined by UV–visible spectroscopic techniques in the wavelength range of 200–800 nm. The high dielectric properties and alternating current conductivity of the composite was studied in the temperature range 313–373 K. It was found that the synthesized polymeric nanocomposite owned fairly suitable dielectric and optical properties for its application in actuators, conductive paints and for many other purposes.

  19. Preparation of polymeric nanocapsules by γ-ray initiated miniemulsion polymerization stabilized by polymeric surfactant

    International Nuclear Information System (INIS)

    An alkali soluble polymeric surfactant, copolymer of butyl methacrylate and methacrylic acid, has been prepared by free radical solution polymerization initiated by γ-ray and used as stabilizer in preparation of polymeric nanocapsules by γ-ray initiated miniemulsion polymerization. Effect of the amount of surfactant and costabilizer (hexadecane) and the styrene/hexadecane ratio on the morphological characteristics of the polymer/oil composite particle was systematically studied. The morphologies of final latexes particles were compared with those obtained by γ-ray initiated miniemulsion polymerization used SDS as surfactant. The results indicated that the structure can be adjusted to cover the whole range from independent particles over partially engulfed structures to structurally integer nanocapsules by varying the parameters such as the type and amount of surfactant and the styrene/hexadecane ratio, as well as dose rate. The use of this polymeric surfactant leads to large amounts of nanocapsules in the case of a lower concentration of hexadecane, which is due to the graft reaction between polymer and polymeric surfactant. (authors)

  20. Attosecond clocking of scattering dynamics in dielectrics

    Science.gov (United States)

    Kling, Matthias

    2016-05-01

    In the past few years electronic-device scaling has progressed rapidly and miniaturization has reached physical gate lengths below 100 nm, heralding the age of nanoelectronics. Besides the effort in size scaling of integrated circuits, tremendous progress has recently been made in increasing the switching speed where strong-field-based ``dielectric-electronics'' may push it towards the petahertz frontier. In this contest, the investigation of the electronic collisional dynamics occurring in a dielectric material is of primary importance to fully understand the transport properties of such future devices. Here, we demonstrate attosecond chronoscopy of electron collisions in SiO2. In our experiment, a stream of isolated aerodynamically focused SiO2 nanoparticles of 50 nm diameter was delivered into the laser interaction region. Photoemission is initiated by an isolated 250 as pulse at 35 eV and the electron dynamics is traced by attosecond streaking using a delayed few-cycle laser pulse at 700 nm. Electrons were detected by a kilohertz, single-shot velocity-map imaging spectrometer, permitting to separate frames containing nanoparticle signals from frames containing the response of the reference gas only. We find that the nanoparticle photoemission exhibits a positive temporal shift with respect to the reference. In order to understand the physical origin of the shift we performed semi-classical Monte-Carlo trajectory simulations taking into account the near-field distributions in- and outside the nanoparticles as obtained from Mie theory. The simulations indicate a pronounced dependence of the streaking time shift near the highest measured electron energies on the inelastic scattering time, while elastic scattering only shows a small influence on the streaking time shift for typical dielectric materials. We envision our approach to provide direct time-domain access to inelastic scattering for a wide range of dielectrics.

  1. An experimental investigation of the dielectric properties of electrorheological fluids

    International Nuclear Information System (INIS)

    A home-made electrorheological (ER) fluid, known as ETSERF, has been created with suspension-based powders dispersed in silicone oil. Because of the special structure of their particles, ETSERF suspensions present a complex behavior. In the absence of an electric field, the ETSERF fluid manifests a near-Newtonian behavior, but when an electric field is applied, it exhibits a pseudoplastic behavior with yield stress. The ER effect under DC electric fields has been experimentally investigated using both hydrous and anhydrous ER fluids. The ER properties are strongly dependent on the dielectric properties of ETSERF suspensions, and hydrous ER fluids have a high dielectric constant and a high relaxation frequency which show a strong electrorheological effect. The relationship between the electrorheological effect and the permittivity of ER fluids has also been extensively studied. Experimental results show that the interfacial polarization plays an important role in the electrorheological phenomenon. The ageing of ETSERF fluids was also studied and it was found that the dielectric properties (mainly the dielectric loss tangent) and ER properties are strongly related to the duration of ageing. A fresh ETSERF suspension exhibits high relaxation frequency and high dielectric constant. These results are mainly explained by the effect of interfacial polarizations

  2. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

    Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

    2006-01-31

    Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles. PMID:16430253

  3. Positronium at polymeric surface

    International Nuclear Information System (INIS)

    Annihilation of slow positrons at a polymeric surface has been discussed in terms of positron diffusion and trapping of positronium into free volume holes. The above model has been used to calculate the ortho-positronium lifetime (τ3) in polystyrene (PS), epoxy resin film, polyurethane (PU) and polytetrafluroethylene (PTFE) as a function of temperature, incident positron energy and mean implantation depth. The results have been compared with the experimental observations of other authors. The variation in τ3 with respect to temperature clearly demonstrates a discontinuity in the curve at Tg corresponding to the glass transition temperature. The variation of calculated τ3 shows that the lifetime increases significantly above Tg however, below Tg it increases only slowly. This is a direct consequence of the change in the size of free volume holes. The Tg has been found to be dependent both on positron energy and density of the polymer. Large variation in τ3 has been observed at low energies suggesting a significant structure of free volume holes near the surface. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Nanoparticles of complex metal oxides synthesized using the reverse-micellar and polymeric precursor routes

    Indian Academy of Sciences (India)

    Ashok K Ganguli; Tokeer Ahmad; Padam R Arya; Pika Jha

    2005-11-01

    Current interest in the properties of materials having grains in the nanometer regime has led to the investigation of the size-dependent properties of various dielectric and magnetic materials. We discuss two chemical methods, namely the reverse-micellar route and the polymeric citrate precursor route used to obtain homogeneous and monophasic nanoparticles of several dielectric oxides like BaTiO3, Ba2TiO4, SrTiO3, PbTiO3, PbZrO3 etc. In addition we also discuss the synthesis of some transition metal (Mn and Cu) oxalate nanorods using the reverse-micellar route. These nanorods on decomposition provide a facile route to the synthesis of transition metal oxide nanoparticles. We discuss the size dependence of the dielectric and magnetic properties in some of the above oxides.

  5. Microwave pyrolisis of polymeric materials

    OpenAIRE

    A.Undri; L.Rosi; M. FREDIANI; P. Frediani

    2011-01-01

    The polymeric materials consumption are growing ceaselessly in the world even in spite of the financial crisis. World rubber demand, for instance, is foreseen to increase up to 4% annually to 26.5 million metric tons in 2011. Therefore the disposal of waste polymers is a serious environmental problem against which public is becoming more aware. The interest of waste polymeric materials disposal is focused on new ways of dealing rather than land filling or incineration. The pyrolysis of polyme...

  6. Polyolefin nanocomposites in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Galland, Griselda Barrera; Fim, Fabiana de C.; Milani, Marceo A.; Silva, Silene P. da; Forest, Tadeu; Radaelli, Gislaine, E-mail: griselda.barrera@ufrgs.br [Universidade Federal do Rio Grande de Sul - UFRGS, Porto Alegre, RS (Brazil); Basso, Nara R.S. [Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil); Quijada, Raul [Universidad de Chile, Santiago (Chile)

    2011-07-01

    Polyethylene and polypropylene nanocomposites using grapheme nanosheets and treated chrysotile have been synthesized by in situ polymerization using metallocene catalysts. The fillers have been submitted to acid, thermal and/ou ultrasound treatments before to introduce them into the polymerization reactor. A complete characterization of the fillers has been done. The nanocomposites have been characterized by SEM, TEM, DRX and AFM. The thermal, mechanic -dynamic, mechanical and electrical properties of the nanocomposites are discussed. (author)

  7. Ethylene polymerization and polyethylene functionalization

    OpenAIRE

    Marín Càmara, Ariadna

    2010-01-01

    Polyolefins have become ubiquitous and are large volume commodity materials. Of current interest is the preparation of speciality polymers incorporating polyethylene (PE), which often requires polymer chain-end manipulation. Ethylene polymerization by a neodymium catalyst in conjunction with n-butyloctylmagnesium (BOMg) is based on a reversible chain-transfer between Nd (where PE chains grow) and Mg (where PE chains rest). Using a large BOMg/Nd ratio for ethylene polymerization leads to m...

  8. Donor Schiff Base Polymeric Complexes

    Directory of Open Access Journals (Sweden)

    Shubhangi N. Kotkar

    2013-01-01

    Full Text Available A series of new polymeric complexes of Mn(II, Co(II, Ni(II, Cu(II, and Zn(II were prepared with a Schiff base ligand derived from condensation of 2,4-dihydroxy acetophenone and p-phenylene diamine and characterized by elemental analysis and IR and NMR spectral data. The antimicrobial activity of the Schiff base and its polymeric complexes have been studied.

  9. Characterization of a Dielectric Barrier Plasma Gun Discharging at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guang-Qiu; GE Yuan-Jing; ZHANG Yue-Fei; CHEN Guang-Liang

    2004-01-01

    @@ We develop a plasma gun based on dielectric barrier discharge and working at atmospheric pressure. A theoretical model to predict the gun discharge voltage is built, which is in agreement with the experimental results. After investigating the characterization of discharging gun and utilizing it for polymerization, we find that the gun can be used as a source to generate a stable uniform plasma for different plasma-processing technologies.

  10. PEO-like Plasma Polymers Prepared by Atmospheric Pressure Surface Dielectric Barrier Discharge

    Czech Academy of Sciences Publication Activity Database

    Gordeev, I.; Choukourov, A.; Šimek, Milan; Prukner, Václav; Biederman, H.

    2012-01-01

    Roč. 9, č. 8 (2012), s. 782-791. ISSN 1612-8850 R&D Projects: GA ČR(CZ) GD104/09/H080 Institutional research plan: CEZ:AV0Z20430508 Keywords : fibrinogen * non-fouling properties * PEO * plasma polymerization * surface dielectric barrier discharge Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.730, year: 2012

  11. Metallo-Dielectric Multilayer Structure for Lactose Malabsorption Diagnosis through H2 Breath Test

    OpenAIRE

    Cioffi, N.; de Ceglia, D.; De Sario, M; D'Orazio, A; Petruzzelli, V.(Dipartimento di Ingegneria Elettrica e dell'Informazione – Politecnico di Bari, Bari, Italy); F. Prudenzano; Scalora, M.; Trevisi, S.; Vincenti, M. A.

    2007-01-01

    A metallo-dielectric multilayer structure is proposed as a novel approach to the analysis of lactose malabsorption. When lactose intolerance occurs, the bacterial overgrowth in the intestine causes an increased spontaneous emission of H2 in the human breath. By monitoring the changes in the optical properties of a multilayer palladium-polymeric structure, one is able to detect the patient's disease and the level of lactose malabsorption with high sensitivity and rapid response.

  12. Multilayer optical dielectric coating

    Science.gov (United States)

    Emmett, John L.

    1990-01-01

    A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

  13. AQUEOUS STABLE FREE RADICAL POLYMERIZATION PROCESSES

    Institute of Scientific and Technical Information of China (English)

    Andrea R. Szkurhan; Michael K. Georges

    2004-01-01

    An overview of aqueous polymerizations, which include emulsion, miniemulsion and suspension polymerizations,under stable free radical polymerization (SFRP) conditions is presented. The success of miniemulsion and suspension SFRP polymerizations is contrasted with the difficulties associated with obtaining a stable emulsion polymerization. A recently developed unique microprecipitation technique is referenced as a means of making submicron sized particles that can be used to achieve a stable emulsion SFRP process.

  14. Harnessing large deformation and instabilities of soft dielectrics: Theory, experiment, and application

    Science.gov (United States)

    Zhao, Xuanhe; Wang, Qiming

    2014-06-01

    Widely used as insulators, capacitors, and transducers in daily life, soft dielectrics based on polymers and polymeric gels play important roles in modern electrified society. Owning to their mechanical compliance, soft dielectrics subject to voltages frequently undergo large deformation and mechanical instabilities. The deformation and instabilities can lead to detrimental failures in some applications of soft dielectrics such as polymer capacitors and insulating gels but can also be rationally harnessed to enable novel functions such as artificial muscle, dynamic surface patterning, and energy harvesting. According to mechanical constraints on soft dielectrics, we classify their deformation and instabilities into three generic modes: (i) thinning and pull-in, (ii) electro-creasing to cratering, and (iii) electro-cavitation. We then provide a systematic understanding of different modes of deformation and instabilities of soft dielectrics by integrating state-of-the-art experimental methods and observations, theoretical models, and applications. Based on the understanding, a systematic set of strategies to prevent or harness the deformation and instabilities of soft dielectrics for diverse applications are discussed. The review is concluded with perspectives on future directions of research in this rapidly evolving field.

  15. Polymeric materials for neovascularization

    Science.gov (United States)

    DeVolder, Ross John

    Revascularization therapies have emerged as a promising strategy to treat various acute and chronic wounds, cardiovascular diseases, and tissue defects. It is common to either administer proangiogenic growth factors, such as vascular endothelial growth factor (VEGF), or transplant cells that endogenously express multiple proangiogenic factors. Additionally, these strategies utilize a wide variety of polymeric systems, including hydrogels and biodegradable plastics, to deliver proangiogenic factors in a sophisticated manner to maintain a sustained proangiogenic environment. Despite some impressive results in rebuilding vascular networks, it is still a challenging task to engineer mature and functional neovessels in target tissues, because of the increasing complexities involved with neovascularization applications. To resolve these challenges, this work aims to design a wide variety of proangiogenic biomaterial systems with tunable properties used for neovascularization therapies. This thesis describes the design of several biomaterial systems used for the delivery of proangiogenic factors in neovascularization therapies, including: an electrospun/electrosprayed biodegradable plastic patch used for directional blood vessel growth (Chapter 2), an alginate-g-pyrrole hydrogel system that biochemically stimulates cellular endogenous proangiogenic factor expression (Chapter 3), an enzyme-catalyzed alginate-g-pyrrole hydrogel system for VEGF delivery (Chapter 4), an enzyme-activated alginate-g-pyrrole hydrogel system with systematically controllable electrical and mechanical properties (Chapter 5), and an alginate-g-pyrrole hydrogel that enables the decoupled control of electrical conductivity and mechanical rigidity and is use to electrically stimulate cellular endogenous proangiogenic factor expression (Chapter 6). Overall, the biomaterial systems developed in this thesis will be broadly useful for improving the quality of a wide array of molecular and cellular based

  16. Dielectrical properties of PANI/TiO2 nanocomposites

    Science.gov (United States)

    Chaturmukha, V. S.; Naveen, C. S.; Rajeeva, M. P.; Avinash, B. S.; Jayanna, H. S.; Lamani, Ashok R.

    2016-05-01

    Conducting polyaniline/titanium dioxide (PANI/TiO2) composites have been succesfully synthesized by insitu polymerization technique. The PANI/TiO2 nanocomposites of different compositions were prepared by varying weight percentage of TiO2 nanoparticles such as 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% into the fixed amount of the aniline monomer. The prepared powder samples were characterized by X-ray diffractometer (XRD) and Scanning electron microscope (SEM). The intensity of diffraction peaks for PANI/TiO2 composites is lower than that for TiO2. SEM pictures show that the nanocomposite were prepared in the form of long PANi chains decorated with TiO2 nanoparticles. The dielectric properties and AC conductivity were studied in the frequency range1K Hz-10M Hz. At higher frequencies, the composites exhibit almost zero dielectric loss and maximum value of σac is found for a concentration of 20 wt% TiO2 in polyaniline. The interface between polyaniline and TiO2 plays an important role in yielding a large dielectric constant in nanocomposites.

  17. Research progress on space charge characteristics in polymeric insulation

    Science.gov (United States)

    Zhang, Yibo; Christen, Thomas; Meng, Xing; Chen, Jiansheng; Rocks, Jens

    2016-03-01

    Due to their excellent electrical insulation properties and processability, polymer materials are used in many electrical products. It is widely believed that space charge plays an important role for the electric field distribution, conduction, ageing, and electric breakdown of polymeric insulation. This paper reviews measurements and characteristics of space charge behavior which mainly determined by the pulsed electro-acoustic (PEA) measurement technique. Particular interests are the effects of the applied voltage, the electrodes, temperature, humidity, microstructure, additives, and filler materials on accumulation, distribution, transport, and the decay of space charge in polymeric materials. This review paper is to provide an overview on various space charge effects under different conditions, and also to summarize the information for polymeric materials with suppressed space charge and improved electrical behavior.

  18. Dielectric elastomer pump for artificial organisms

    Science.gov (United States)

    Bowers, Amy E.; Rossiter, Jonathan M.; Walters, Peter J.; Ieropoulos, Ioannis A.

    2011-04-01

    This paper presents a bio-inspired, dielectric elastomer (DE) based tubular pumping unit, developed for eventual use as a component of an artificial digestive tract onboard a microbial fuel cell powered robot (EcoBot). The pump effects fluid displacement by direct actuation of the tube wall as opposed to excitation by an external body. The actuator consists of a DE tube moulded from silicone, held in a negative pressure chamber, which is used for prestraining the tube. The pump is coupled with custom designed polymeric check valves in order to rectify the fluid flow and assess the performance of the unit. The valves exhibited the necessary low opening pressures required for use with the actuator. The tube's actuation characteristics were measured both with and without liquid in the system. Based on these data the optimal operating conditions for the pump are discussed. The pump and valve system has achieved flowrates in excess of 40μl/s. This radially contracting/expanding actuator element is the fundamental component of a peristaltic pump. This 'soft pump' concept is suitable for biomimetic robotic systems, or for the medical or food industries where hard contact with the delivered substrate may be undesirable. Future work will look at connecting multiple tubes in series in order to achieve peristalsis.

  19. Electromagnetic identification of dielectric materials

    Directory of Open Access Journals (Sweden)

    A. F. Yanenko

    2010-05-01

    Full Text Available The electromagnetic features and parameters of dielectric materials, which are used in light industry and stomatology. The results of measuring are analyzed and the method of authentication is offered.

  20. Nonlinear Dielectric Response of Water Treed XLPE Cable Insulation

    Energy Technology Data Exchange (ETDEWEB)

    Hvidsten, Sverre

    1999-07-01

    Condition assessment of XLPE power cables is becoming increasingly important for the utilities, due to a large number of old cables in service with high probability of failure caused by water tree degradation. The commercial available techniques are generally based upon measurements of the dielectric response, either by time (polarisation/depolarisation current or return voltage) or frequency domain measurements. Recently it has been found that a high number of water trees in XLPE insulated cables causes the dielectric response to increase more than linearly with increasing test voltage. This nonlinear feature of water tree degraded XLPE insulation has been suggested to be of a great importance, both for diagnostic purposes, and for fundamental understanding of the water tree phenomenon itself. The main purpose of this thesis have been to study the nonlinear feature of the dielectric response measured on watertreed XLPE insulation. This has been performed by dielectric response measurements in both time and frequency domain, numerical calculations of losses of simplified water tree models, and fmally water content and water permeation measurements on single water trees. The dielectric response measurements were performed on service aged cable samples and laboratory aged Rogowski type objects. The main reason for performing laboratory ageing was to facilitate diagnostic testing as a function of ageing time of samples containing mainly vented water trees. A new method, based upon inserting NaC1 particles at the interface between the upper semiconductive screen and the insulation, was found to successfully enhance initiation and growth of vented water trees. AC breakdown strength testing show that it is the vented water trees that reduce the breakdown level of both the laboratory aged test objects and service aged cable samples. Vented water treeing was found to cause the dielectric response to become nonlinear at a relatively low voltage level. However, the measured

  1. Plasma polymerization for cell adhesive/anti-adhesive implant coating

    Science.gov (United States)

    Meichsner, Juergen; Testrich, Holger; Rebl, Henrike; Nebe, Barbara

    2015-09-01

    Plasma polymerization of ethylenediamine (C2H8N2, EDA) and perfluoropropane (C3F8, PFP) with admixture of argon and hydrogen, respectively, was studied using an asymmetric 13.56 MHz CCP. The analysis of the plasma chemical gas phase processes for stable molecules revealed consecutive reactions: C2H8N2 consumption, intermediate product NH3, and main final product HCN. In C3F8- H2 plasma the precursor molecule C3F8 and molecular hydrogen are consumed and HF as well as CF4 and C2F6 are found as main gaseous reaction products. The deposited plasma polymer films on the powered electrode are strongly cross-linked due to ion bombardment. The stable plasma polymerized films from EDA are characterized by high content of nitrogen with N/C ratio of about 0.35. The plasma polymerized fluorocarbon film exhibit a reduced F/C ratio of about 1.2. Adhesion tests with human osteoblast cell line MG-63 on coated Ti6Al4V samples (polished) compared with uncoated reference sample yielded both, the enhanced cell adhesion for plasma polymerized EDA and significantly reduced cell adhesion for fluorocarbon coating, respectively. Aging of the plasma polymerized EDA film, in particular due to the reactions with oxygen from air, showed no significant change in the cell adhesion. The fluorocarbon coating with low cell adhesion is of interest for temporary implants. Funded by the Campus PlasmaMed.

  2. Dynamic dielectric properties and the γ transition of bromine doped polyacrylonitrile

    Directory of Open Access Journals (Sweden)

    2007-10-01

    Full Text Available Based on monitoring the γ process (the lowest temperature-relaxation in polyacrylonitrile (PAN by dynamic dielectric spectroscopy, new evidence for the formation of a charge transfer complex between bromine dopants and nitrile groups is presented. The experimental work is carried out on PAN and nitrile polymerized PAN with and without bromine doping and the effects of these factors on the γ process are measured. Nitrile polymerization results in diminishing of the γ process and in a 15% increase in its activation energy, whereas bromine doping produces splitting of the original γ process in PAN – coupled with a significant activation energy increase – and its complete disappearance in nitrile polymerized PAN. Both the splitting of the γ process and the higher activation energy reflect bromine-nitrile adduct formation..

  3. Resveratrol immobilization and release in polymeric hydrogels

    International Nuclear Information System (INIS)

    Resveratrol (3, 4', 5-trihydroxystilbene) is a polyphenolic produced by a wide variety of plants in response to injury and found predominantly in grape skins. This active ingredient has been shown to possess benefits for the health, such as the antioxidant capacity which is related to the prevention of several types of cancer and skin aging. However, the oral bioavailability of resveratrol is poor and makes its topical application interesting. The purpose of this study was to immobilize resveratrol in polymeric hydrogels to obtain a release device for topical use. The polymeric matrices composed of poli(N-vinyl-2-pyrrolidone) (PVP), poly(ethyleneglycol) (PEG) and agar or PVP and glycerol irradiated at 20 kGy dose were physical-chemically characterized by gel fraction and swelling tests and its preliminary biocompatibility by in vitro test of cytotoxicity using the technique of neutral red uptake. Due to low solubility of resveratrol in water, the addition of 2% ethanol to the matrices was verified. All matrices showed a high crosslinking degree, capacity of swelling and the preliminary cytotoxicity test showed nontoxicity effect. The devices were obtained by resveratrol immobilization in polymeric matrices, carried out in a one-or-two-steps process, that is, before or after irradiation, respectively. The one step resveratrol devices were characterized by gel fraction, swelling tests and preliminary biocompatibility, and their properties were maintained even after the resveratrol incorporation. The devices containing 0,05% of resveratrol obtained by one-step process and 0,1% of resveratrol obtained by two-steps process were submitted to the release test during 24 h. Resveratrol quantification was done by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that only the devices obtained by two-step process release the resveratrol, which demonstrate antioxidant capacity after the release. (author)

  4. Open dielectric branes

    International Nuclear Information System (INIS)

    We derive leading terms in the effective actions describing the coupling of bulk supergravity fields to systems of arbitrary numbers of Dp-branes and D(p+4)-branes in type-IIA/IIB string theory. We use these actions to investigate the physics of Dp-D(p+4) systems in the presence of weak background fields. In particular, we construct various solutions describing collections of Dp-branes blown up into open D(p+2)-branes ending on D(p+4)-branes. The configurations are stabilized by the presence of background fields and represent an open-brane analogue of the Myers dielectric effect. To deduce the D-brane actions, we use supersymmetry to derive operators corresponding to moments of various conserved currents in the Berkooz-Douglas matrix model of M-theory in the presence of longitudinal M5-branes and then use dualities to relate these operators to the worldvolume operators appearing in the Dp-D(p+4)-brane effective actions. (author)

  5. Dielectric coated ion thruster

    International Nuclear Information System (INIS)

    This paper describes an ion accelerator apparatus. It comprises: a source of free electrons; a chamber connected to the source of free electrons; means for accelerating the free electrons within the chamber; means for introducing a flow of a gas comprising atoms having a neutral charge into the chamber, the accelerated free electrons colliding with the atoms of the gas causing valence shell electrons to be lost by the atoms, producing therefrom a plasma of positively charged ions; and a metallic grid plate comprising one wall of the chamber and provided with spaced apart perforations extending therethrough, the grid plate being coated on both its inner and outer sides with a layer of an insulating material having a much higher dielectric constant that the metallic grid plate, the grid plate being connected to an electric potential substantially more negative than the positively charged ions so that ions drifting into the vicinity of the metallic grid plate are accelerated toward it, passing out of the chamber through the perforations. The surface of the layer of insulating material on the inner side of the metallic grid plate has an electric potential approximately equal to that of the plasma and thus acting as a screen grid, both layers of insulating material protecting the metallic grid plate from erosion by charged ions and insulating the chamber against thermal and electrical losses

  6. Dielectric and permeability

    Science.gov (United States)

    Cole, K. D.

    1982-01-01

    Using the unabridged Maxwell equations (including vectors D, E and H) new effects in collisionless plasmas are uncovered. In a steady state, it is found that spatially varying energy density of the electric field (E perpendicular) orthogonal to B produces electric current leading, under certain conditions, to the relationship P perpendicular+B(2)/8 pi-epsilon E perpendicular(2)/8 pi = constant, where epsilon is the dielectric constant of the plasma for fields orthogonal to B. In steady state quasi-two-dimensional flows in plasmas, a general relationship between the components of electric field parallel and perpendicular to B is found. These effects are significant in goephysical and astrophysical plasmas. The general conditions for a steady state in collisionless plasma are deduced. With time variations in a plasma, slow compared to ion-gyroperiod, there is a general current, (j*), which includes the well-known polarisation current, given by J*=d/dt (ExM)+(PxB)xB B(-2) where M and P are the magnetization and polarization vectors respectively.

  7. Experimental Studies of Antenna Miniaturization Using Magneto-Dielectric and Dielectric Materials

    OpenAIRE

    Karilainen, Antti O.; Ikonen, Pekka M. T.; Constantin R. Simovski; Tretyakov, Sergei A.; Lagarkov, Andrey N.; Maklakov, Sergei A.; Rozanov, Konstantin N.; Starostenko, Sergey N.

    2009-01-01

    Measurement results for a meandered planar inverted-F antenna (PIFA) loaded with magneto-dielectric and dielectric materials are presented. Figures of merit and ways to compare antennas with different fillings materials are discussed. The used magneto-dielectric material is described, the radiation mechanism of the meandered PIFA is studied, and the proper position for dielectric and magneto-dielectric filling is discussed and identified. Identical-size antennas with dielectric and magneto-di...

  8. Surface glycosylation of polymeric membranes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Surface glycosylation of polymeric membranes has been inspired by the structure of natural biomem-branes. It refers to that glycosyl groups are introduced onto the membrane surface by various strate-gies, which combine the separation function of the membrane with the biological function of the sac-charides in one system. In this review, progress in the surface glycosylation of polymeric membranes is highlighted in two aspects, i.e. the glycosylation methods and the potential applications of the sur-face-glycosylated membranes.

  9. On-demand photoinitiated polymerization

    Science.gov (United States)

    Boydston, Andrew J; Grubbs, Robert H; Daeffler, Chris; Momcilovic, Nebojsa

    2013-12-10

    Compositions and methods for adjustable lenses are provided. In some embodiments, the lenses contain a lens matrix material, a masking compound, and a prepolymer. The lens matrix material provides structure to the lens. The masking compound is capable of blocking polymerization or crosslinking of the prepolymer, until photoisomerization of the compound is triggered, and the compound is converted from a first isomer to a second isomer having a different absorption profile. The prepolymer is a composition that can undergo a polymerization or crosslinking reaction upon photoinitiation to alter one or more of the properties of the lenses.

  10. Polymerization in emulsion microdroplet reactors

    Science.gov (United States)

    Carroll, Nick J.

    The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic fluorosurfactants allows fluorocarbon oils to be used as the continuous phase in a water-free emulsion. Such emulsions enable the encapsulation of almost any hydrocarbon compound in droplets that may be used as separate compartments for water-sensitive syntheses. Here, we exemplify the promise of this approach by suspension polymerization of polyurethanes (PU), in which the liquid precursor is emulsified into droplets that are then converted 1:1 into polymer particles. The stability of the droplets against coalescence upon removal of the continuous phase by evaporation confirms the formation of solid PU particles. These results prove that the water-free environment of fluorocarbon based emulsions enables high conversion. We produce monodisperse, cross-linked, and fluorescently labeled PU-latexes with controllable mesh size through microfluidic emulsification in a simple one-step process. A novel method for the fabrication of monodisperse mesoporous silica particles is presented. It is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to

  11. Degradable polymeric materials for osteosynthesis: Tutorial

    Directory of Open Access Journals (Sweden)

    D Eglin

    2008-12-01

    Full Text Available This report summarizes the state of the art and recent developments and advances in the use of degradable polymers devices for osteosynthesis. The current generation of biodegradable polymeric implants for bone repair utilising designs copied from metal implants, originates from the concept that devices should be supportive and as “inert” substitute to bone tissue. Today degradable polymeric devices for osteosynthesis are successful in low or mild load bearing applications. However, the lack of carefully controlled randomized prospective trials that document their efficacy in treating a particular fracture pattern is still an issue. Then, the choice between degradable and non-degradable devices must be carefully weighed and depends on many factors such as the patient age and condition, the type of fracture, the risk of infection, etc. The improvement of the biodegradable devices mechanical properties and their degradation behaviour will have to be achieved to broaden their use. The next generation of biodegradable implants will probably see the implementation of the recent gained knowledge in cell-material interactions and cells therapy, with a better control of the spatial and temporal interfaces between the material and the surrounding bone tissue.

  12. Study of Influencing Factors and the Mechanism of Preparing Triazinedithiol Polymeric Nanofilms on Aluminum Surfaces

    Directory of Open Access Journals (Sweden)

    Yanni Li

    2010-11-01

    Full Text Available Triazinedithiol polymeric nanofilm was prepared on a pure aluminum surface by electrochemical polymerization of AF17N. The mechanism of the process was proposed and electrochemical polymerization parameters were investigated. The triazinedithiol polymeric nanofilm had notable lubricity, high dielectric property and superhydrophobic property due to the allyl and fluoro alkyl groups in the AF17N monomer. The chemical structure of poly (6-(N-allyl-1,1,2,2-tetrahydroperfluorodecylamino-1,3,5-triazine-2,4-dithiol monosodium nanofilm (PAF17 was investigated by analysis of FT-IR spectra and X-ray photoelectron spectroscopy (XPS. The optimal conditions for the preparation process were based on the data of film weight and thickness. The optimal parameters of monomer concentration, electropolymerization time and temperature were 5 mM, 6 min and 15 °C, respectively. The electropolymerization mechanism was a radical polymerization reaction. It is expected that this technique will be applied in industrial fields for aluminum and aluminum alloy to achieve functional surfaces.

  13. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  14. The Viscosity of Polymeric Fluids.

    Science.gov (United States)

    Perrin, J. E.; Martin, G. C.

    1983-01-01

    To illustrate the behavior of polymeric fluids and in what respects they differ from Newtonian liquids, an experiment was developed to account for the shear-rate dependence of non-Newtonian fluids. Background information, procedures, and results are provided for the experiment. Useful in transport processes, fluid mechanics, or physical chemistry…

  15. Low vibration polymeric composite engine

    Science.gov (United States)

    Guimond, David P.; Muench, Rolf K.

    1994-12-01

    An internal combustion engine is constructed with metallic parts in its regions which are subjected to high stress (temperature, pressure) during combustion and polymeric materials in its regions which are subjected to relatively lower stresses. The integrated construction helps realize increased power densities and reductions on engine noise without compromising engine performance. V-configuration Diesel engines particularly benefit from this construction.

  16. Sleeving nanocelluloses by admicellar polymerization.

    Science.gov (United States)

    Trovatti, Eliane; Ferreira, Adriane de Medeiros; Carvalho, Antonio José Felix; Ribeiro, Sidney José Lima; Gandini, Alessandro

    2013-10-15

    This investigation reports the first application of admicellar polymerization to cellulose nanofibers in the form of bacterial cellulose, microfibrillated cellulose, and cellulose nanowhiskers using styrene and ethyl acrylate. The success of this physical sleeving was assessed by SEM, FTIR, and contact angle measurements, providing an original and simple approach to the modification of cellulose nanofibers in their pristine aqueous environment. PMID:23921337

  17. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter; Hassager, Ole

    The capillary thinning of a polymeric filament is analysed experimentally as well as by means of numerical simulation. The experimental procedure is as follows. Initially a liquid sample is kept between two cylindrical plates. Then the bottom plate is lowered under gravity to yield a given strain...

  18. Chemical oxidative polymerization of benzocaine

    Czech Academy of Sciences Publication Activity Database

    Marjanovic, B.; Juranic, I.; Ciric-Marjanovic, G.; Pašti, I.; Trchová, Miroslava; Holler, Petr

    2011-01-01

    Roč. 71, č. 7 (2011), s. 704-712. ISSN 1381-5148 R&D Projects: GA ČR GA203/08/0686 Institutional research plan: CEZ:AV0Z40500505 Keywords : benzocaine * electro-active oligomer * oxidative polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.479, year: 2011

  19. Thermal Polymerization of N-Butyl Acrylate

    Science.gov (United States)

    Ingham, J. D.

    1982-01-01

    Simple new polymerization method enables production of n-butyl acrylate polymer of desired high molecular weight, without disadvantages that usually attend more conventional methods. Process, which is hybrid of thermal, solution, and emulsion polymerization methods, involves controlled thermal polymerization of monomer at moderate temperatures without use of catalysts or additives.

  20. All-dielectric bianisotropic nanoantennas

    CERN Document Server

    Alaee, Rasoul; Rahimzadegan, Aso; Mirmoosa, Mohammad S; Kivshar, Yuri S; Rockstuhl, Carsten

    2015-01-01

    The study of high-index dielectric nanoparticles and nanoantennas currently attracts a lot of attention. They do not suffer from absorption but promise to provide control on the properties of light comparable to plasmonic nanoantennas. To further advance the field, it is important to identify versatile dielectric nanoantennas with unconventional properties. Here, we show that breaking the symmetry of an all-dielectric nanoantenna leads to a geometrically tunable magneto-electric coupling, i.e. a strong bianisotropy. The suggested nanoantenna exhibits different backscatterings and, as an interesting consequence, different optical scattering forces for opposite illumination directions. An array of such nanoantennas provides different reflection phases when illuminated from opposite directions. With a proper geometrical tuning, this bianisotropic nanoantenna is capable of providing a $2\\pi$ phase change in the reflection spectrum while possessing a rather large and constant amplitude. This allows creating reflec...

  1. Materials Fundamentals of Gate Dielectrics

    CERN Document Server

    Demkov, Alexander A

    2006-01-01

    This book presents materials fundamentals of novel gate dielectrics that are being introduced into semiconductor manufacturing to ensure the continuous scalling of the CMOS devices. This is a very fast evolving field of research so we choose to focus on the basic understanding of the structure, thermodunamics, and electronic properties of these materials that determine their performance in device applications. Most of these materials are transition metal oxides. Ironically, the d-orbitals responsible for the high dielectric constant cause sever integration difficulties thus intrinsically limiting high-k dielectrics. Though new in the electronics industry many of these materials are wel known in the field of ceramics, and we describe this unique connection. The complexity of the structure-property relations in TM oxides makes the use of the state of the art first-principles calculations necessary. Several chapters give a detailed description of the modern theory of polarization, and heterojunction band discont...

  2. High permittivity gate dielectric materials

    CERN Document Server

    2013-01-01

    "The book comprehensively covers all the current and the emerging areas of the physics and the technology of high permittivity gate dielectric materials, including, topics such as MOSFET basics and characteristics, hafnium-based gate dielectric materials, Hf-based gate dielectric processing, metal gate electrodes, flat-band and threshold voltage tuning, channel mobility, high-k gate stack degradation and reliability, lanthanide-based high-k gate stack materials, ternary hafnia and lanthania based high-k gate stack films, crystalline high-k oxides, high mobility substrates, and parameter extraction. Each chapter begins with the basics necessary for understanding the topic, followed by a comprehensive review of the literature, and ultimately graduating to the current status of the technology and our scientific understanding and the future prospects."

  3. Dielectric Bow-tie Nanocavity

    CERN Document Server

    Lu, Qijing; Zou, Chang-Ling

    2013-01-01

    We propose a novel dielectric bow-tie nanocavity consisting of two tip-to-tip opposite triangle semiconductor nanowires, whose end faces are coated by silver nanofilms. Based on the advantages of the dielectric slot and tip structures, and the high reflectivity from the silver mirror, light can be confined in this nanocavity with low loss. We demonstrate that the mode excited in this nanocavity has a deep subwavelength mode volume of 2.8*10^-4 um3 and a high quality factor of 4.9*10^4 (401.3), consequently an ultrahigh Purcell factor of 1.6*10^7 (1.36*10^5), at 4.5 K (300 K) around the resonance wavelength of 1550 nm. This dielectric bow-tie nanocavity may find applications for integrated nanophotonic circuits, such as high-efficiency single photon source, thresholdless nanolaser, and cavity QED strong coupling experiments.

  4. Effect of Polymerization Temperature on Polymerization Degree and Structure of Calcium Polyphosphate

    OpenAIRE

    WU Hang, ZHANG Li-Fang, BAI Wei, MA Chi, XIONG Cheng-Dong

    2012-01-01

    The properties of calcium polyphosphate (CPP) were greatly affected by its polymerization degree. A series of CPP with different polymerization degree were prepared by polymerization of calcium phosphate monobasic monohydrate (MCP) at different temperatures. Polymerization degree was analyzed by liquid state 31P nuclear magnetic resonance (31P―NMR). The effect of different temperature on polymerization degree and structure of CPP was discussed. MCP was ana...

  5. Capacitive Cells for Dielectric Constant Measurement

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  6. Dielectric Bow-tie Nanocavity

    OpenAIRE

    Lu, Qijing; Shu, Fang-Jie; Zou, Chang-Ling

    2013-01-01

    We propose a novel dielectric bow-tie nanocavity consisting of two tip-to-tip opposite triangle semiconductor nanowires, whose end faces are coated by silver nanofilms. Based on the advantages of the dielectric slot and tip structures, and the high reflectivity from the silver mirror, light can be confined in this nanocavity with low loss. We demonstrate that the mode excited in this nanocavity has a deep subwavelength mode volume of 2.8*10^-4 um3 and a high quality factor of 4.9*10^4 (401.3)...

  7. Dielectric relaxation study of gamma irradiated oriented low-density polyethylene

    CERN Document Server

    Suljovrujic, E; Kostoski, D

    2003-01-01

    The influence of drawing, gamma irradiation and accelerated aging on the dielectric relaxation of low-density polyethylene has been studied using dielectric loss tangent measurements in the temperature range from 25 to 325 K and in the frequency range from 10 sup 3 to 10 sup 6 Hz. The intensity, position and activation energy of the gamma- and beta-dielectric relaxations were found to be strongly dependent upon the changes in the microstructure of the amorphous phase induced by uniaxial orientation, oxidation and crosslinking.

  8. Tailoring Dielectric and Actuated Properties of Elastomer Composites by Bioinspired Poly(dopamine) Encapsulated Graphene Oxide.

    Science.gov (United States)

    Ning, Nanying; Ma, Qin; Liu, Suting; Tian, Ming; Zhang, Liqun; Nishi, Toshio

    2015-05-27

    In this study, we obtained dielectric elastomer composites with controllable dielectric and actuated properties by using a biomimetic method. We used dopamine (DA) to simultaneously coat the graphene oxide (GO) and partially reduce GO by self-polymerization of DA on GO. The poly(dopamine) (PDA) coated GO (GO-PDA) was assembled around rubber latex particles by hydrogen bonding interaction between carboxyl groups of carboxylated nitrile rubber (XNBR) and imino groups or phenolic hydroxyl groups of GO-PDA during latex compounding, forming a segregated GO-PDA network at a low percolation threshold. The results showed that the introduction of PDA on GO prevented the restack of GO in the matrix. The dielectric and actuated properties of the composites depend on the thickness of PDA shell. The dielectric loss and the elastic modulus decrease, and the breakdown strength increases with increasing the thickness of PDA shell. The maximum actuated strain increases from 1.7% for GO/XNBR composite to 4.4% for GO-PDA/XNBR composites with the PDA thickness of about 5.4 nm. The actuated strain at a low electric field (2 kV/mm) obviously increases from 0.2% for pure XNBR to 2.3% for GO-PDA/XNBR composite with the PDA thickness of 1.1 nm, much higher than that of other DEs reported in previous studies. Thus, we successfully obtained dielectric composites with low dielectric loss and improved breakdown strength and actuated strain at a low electric field, facilitating the wide application of dielectric elastomers. PMID:25938262

  9. Dielectric Resonator Metasurface for Dispersion Engineering

    OpenAIRE

    Achouri, Karim; Yahyaoui, Ali; Gupta, Shulabh; Rmili, Hatem; Caloz, Christophe

    2016-01-01

    We introduce a practical dielectric metasurface design for microwave frequencies. The metasurface is made of an array of dielectric resonators held together by dielectric connections thus avoiding the need of a mechanical support in the form of a dielectric slab and the spurious multiple reflections that such a slab would generate. The proposed design can be used either for broadband metasurface applications or monochromatic wave transformations. The capabilities of the concept to manipulate ...

  10. Dielectric crystal in the Planck blackbody

    CERN Document Server

    Pardy, Miroslav

    2015-01-01

    The dielectric crystal with the index of refraction n is inserted in the Planck blackbody. The spectral formula for photons in such dielectric medium is derived with the equation for the temperature of internal photons. The derived equation is solved for the constant index of refraction. The photon ow initiates the osmotic pressure of he Debye phonons in the dielectric blackbody. Key words: Thermodynamics, blackbody, photons, phonons, dielectric medium, dispersion.

  11. Dielectric response of the human tooth dentine

    Energy Technology Data Exchange (ETDEWEB)

    Leskovec, J. [Dental Clinic, Faculty of Medicine, University of Ljubljana, Hrvatski trg 6, 1104 Ljubljana (Slovenia); Filipic, C. [Jozef Stefan Institute, P.O. Box 3000, 1001 Ljubljana (Slovenia); Levstik, A. [Jozef Stefan Institute, P.O. Box 3000, 1001 Ljubljana (Slovenia)]. E-mail: adrijan.levstik@ijs.si

    2005-07-15

    Dielectric properties of tooth dentine can be well described by the model which was developed for the dielectric response to hydrating porous cement paste. It is shown that the normalized dielectric constant and the normalized specific conductivity are proportional to the model parameters -bar {sub v0} and {sigma}{sub v}, indicating the deposition of AgCl in the dentine tubules during the duration of the precipitation. The fractal dimension of the tooth dentine was determined by dielectric spectroscopy.

  12. Dielectric response of the human tooth dentine

    International Nuclear Information System (INIS)

    Dielectric properties of tooth dentine can be well described by the model which was developed for the dielectric response to hydrating porous cement paste. It is shown that the normalized dielectric constant and the normalized specific conductivity are proportional to the model parameters -bar v0 and σv, indicating the deposition of AgCl in the dentine tubules during the duration of the precipitation. The fractal dimension of the tooth dentine was determined by dielectric spectroscopy

  13. Casimir-Lifshitz interaction between dielectric heterostructures

    International Nuclear Information System (INIS)

    The interaction between arbitrary dielectric heterostructures is studied within the framework of a recently developed dielectric contrast perturbation theory. It is shown that periodically patterned dielectric or metallic structures lead to oscillatory lateral Casimir-Lifshitz forces, as well as modulations in the normal force as they are displaced with respect to one another. The strength of these oscillatory contributions increases with decreasing gap size and increasing contrast in the dielectric properties of the materials used in the heterostructures.

  14. Casimir-Lifshitz interaction between dielectric heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Azari, Arash; Samanta, Himadri S; Golestanian, Ramin [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)], E-mail: r.golestanian@sheffield.ac.uk

    2009-09-15

    The interaction between arbitrary dielectric heterostructures is studied within the framework of a recently developed dielectric contrast perturbation theory. It is shown that periodically patterned dielectric or metallic structures lead to oscillatory lateral Casimir-Lifshitz forces, as well as modulations in the normal force as they are displaced with respect to one another. The strength of these oscillatory contributions increases with decreasing gap size and increasing contrast in the dielectric properties of the materials used in the heterostructures.

  15. Dielectric response of the human tooth dentine

    Science.gov (United States)

    Leskovec, J.; Filipič, C.; Levstik, A.

    2005-07-01

    Dielectric properties of tooth dentine can be well described by the model which was developed for the dielectric response to hydrating porous cement paste. It is shown that the normalized dielectric constant and the normalized specific conductivity are proportional to the model parameters ɛ and σv, indicating the deposition of AgCl in the dentine tubules during the duration of the precipitation. The fractal dimension of the tooth dentine was determined by dielectric spectroscopy.

  16. Tailoring the Dielectric Layer Structure for Enhanced Performance of Organic Field-Effect Transistors: The Use of a Sandwiched Polar Dielectric Layer

    Directory of Open Access Journals (Sweden)

    Shijiao Han

    2016-07-01

    Full Text Available To investigate the origins of hydroxyl groups in a polymeric dielectric and its applications in organic field-effect transistors (OFETs, a polar polymer layer was inserted between two polymethyl methacrylate (PMMA dielectric layers, and its effect on the performance as an organic field-effect transistor (OFET was studied. The OFETs with a sandwiched dielectric layer of poly(vinyl alcohol (PVA or poly(4-vinylphenol (PVP containing hydroxyl groups had shown enhanced characteristics compared to those with only PMMA layers. The field-effect mobility had been raised more than 10 times in n-type devices (three times in the p-type one, and the threshold voltage had been lowered almost eight times in p-type devices (two times in the n-type. The on-off ratio of two kinds of devices had been enhanced by almost two orders of magnitude. This was attributed to the orientation of hydroxyl groups from disordered to perpendicular to the substrate under gate-applied voltage bias, and additional charges would be induced by this polarization at the interface between the semiconductor and dielectrics, contributing to the accumulation of charge transfer.

  17. Dielectric Properties of Collagen on Plasma Modified Polyvinylidene Fluoride

    Directory of Open Access Journals (Sweden)

    R. M. Dahan

    2012-01-01

    Full Text Available Problem statement: The attachment of biopolymers such as collagen on inert polymeric template created great challenge due to hydrophobic nature of polymeric material. The modification of PVDF for improved adhesion and introduction of specific functionalities have been widely recognized in various industrial applications. Typical methods for modifying polymer surface such as chemical etching and UV irradiation are not favorable as it requires high temperature and the use of chemical solvents. However plasma modification is suitable as it utilizes low heat and a clean environment, thus preventing contamination on the deposited collagen. Approach: Free standing orientated Poly (Vinylidene Fluoride (PVDF films were fabricated by solution casting method and dried in a convention oven. The dried PVDF films were orientated in a tensile machine at temperature 70°C enclosed in a custom made environmental chamber. The pulling rates of 5 mm min-1 were utilized with a draw ratio of 2 (R = Lfinal/Linitial. The PVDF film was plasma treated for 60 sec to enhance the hydrophilic property of PVDF and utilized as template for collagen deposition. The deposited collagen on surface of PVDF was left in desiccators at temperature of 24°C for complete drying. Results: The untreated and plasma-treated PVDF template were observed for water contact angle measurement, the functional group and dielectric properties of collagen were observed and measured by FTIR and SOLARTRON respectively. Conclusion: The orientated PVDF films were produced at pulling speed of 5 mm min-1 and temperature of 70°C. The hydrophobic PVDF surface was transformed to a hydrophilic surface by plasma treatment for collagen deposition. The FTIR result shows the overlapping peaks of C-H and C-F in range 1500-1000 cm-1 which indicates the C-C bonding of collagen and PVDF. The significant increase in dielectric constant is a result from the favorable bonding between collagen and PVDF template.

  18. Impact of dielectric deterioration on the conducted EMI emissions in the DC-DC boost converter

    OpenAIRE

    Musznicki, Piotr; Schanen, Jean-Luc; Granjon, Pierre; Јuszcz, Jarosław

    2011-01-01

    International audience The magnitude of emitted noise generated by DC-DC converters depends on their electrical behavior and parameters. Some of these can change during the converter life time, especially due to some deterioration process. In this paper the impact of the dielectric materials aging is presented using both circuit simulation and a digital signal processing method based on Wiener filtering. The change of the total EMI spectrum as a function of the dielectric property has been...

  19. Magnetic properties of polymerized diphenyloctatetrayne

    International Nuclear Information System (INIS)

    A new type of metal-free ferromagnetic carbon material was obtained by thermal polymerization and electron beam irradiation of diphenyloctatetrayne (DPOT). The isothermal magnetic measurements showed hysteresis loops indicating weak but intrinsic ferromagnetism with Curie temperatures of around 600 K. Electron spin resonance spectroscopy showed that the material contained stable free radicals in the range of 1017–1020 radicals g−1 depending on the polymerization process. The ferromagnetism should be due to high radical concentration although no correlation was observed between them. It was shown that an amorphous ferromagnetic carbon could be obtained from a simple crystalline solid by heating at moderate temperatures. Highlights: ► Diphenyloctatetrayne as a precursor for carbon with high radical concentration. ► The carbon material consists of sp2 configuration. ► A weak intrinsic metal-free ferromagnetism was observed for the carbon products.

  20. Magnetic properties of polymerized diphenyloctatetrayne

    Energy Technology Data Exchange (ETDEWEB)

    Beristain, Miriam F.; Jimenez-Solomon, Maria F.; Ortega, Alejandra; Escudero, Roberto [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Ciudad Universitaria, Mexico DF 04510 (Mexico); Munoz, Eduardo [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Ciudad Universitaria, Mexico DF 01000 (Mexico); Maekawa, Yasunari; Koshikawa, Hiroshi [High Performance Polymer Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Ogawa, Takeshi, E-mail: ogawa@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Ciudad Universitaria, Mexico DF 04510 (Mexico)

    2012-10-15

    A new type of metal-free ferromagnetic carbon material was obtained by thermal polymerization and electron beam irradiation of diphenyloctatetrayne (DPOT). The isothermal magnetic measurements showed hysteresis loops indicating weak but intrinsic ferromagnetism with Curie temperatures of around 600 K. Electron spin resonance spectroscopy showed that the material contained stable free radicals in the range of 10{sup 17}-10{sup 20} radicals g{sup -1} depending on the polymerization process. The ferromagnetism should be due to high radical concentration although no correlation was observed between them. It was shown that an amorphous ferromagnetic carbon could be obtained from a simple crystalline solid by heating at moderate temperatures. Highlights: Black-Right-Pointing-Pointer Diphenyloctatetrayne as a precursor for carbon with high radical concentration. Black-Right-Pointing-Pointer The carbon material consists of sp{sup 2} configuration. Black-Right-Pointing-Pointer A weak intrinsic metal-free ferromagnetism was observed for the carbon products.

  1. SCATTERING FROM RAMIFIED POLYMERIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    M.Benhamou

    2004-01-01

    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  2. Microemulsion Polymerization of Methyl Methacrylat

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (Tg) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher Tg. And the obtained PMMA microlatex has a 30 %-40 % (mass fraction) polymer content, a 0.03 emulsifier/water weight ratio, a 0.05emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.

  3. Counteracting Gravitation In Dielectric Liquids

    Science.gov (United States)

    Israelsson, Ulf E.; Jackson, Henry W.; Strayer, Donald M.

    1993-01-01

    Force of gravity in variety of dielectric liquids counteracted by imposing suitably contoured electric fields. Technique makes possible to perform, on Earth, variety of experiments previously performed only in outer space and at great cost. Also used similarly in outer space to generate sort of artificial gravitation.

  4. Dielectric waveguide amplifiers and lasers

    NARCIS (Netherlands)

    Pollnau, M.

    2014-01-01

    The performance of semiconductor amplifiers and lasers has made them the preferred choice for optical gain on a micro-chip. In the past few years, we have demonstrated that also rare-earth-ion-doped dielectric waveguides show remarkable performance, ranging from a small-signal gain per unit length o

  5. Chemical oxidative polymerization of aminodiphenylamines

    Czech Academy of Sciences Publication Activity Database

    Ciric-Marjanovic, G.; Trchová, Miroslava; Konyushenko, Elena; Holler, Petr; Stejskal, Jaroslav

    2008-01-01

    Roč. 112, č. 23 (2008), s. 6976-6987. ISSN 1520-6106 R&D Projects: GA ČR GA203/08/0686 Grant ostatní: Ministry of Science and Environmental Protection of Serbia(CS) 142047 Institutional research plan: CEZ:AV0Z40500505 Keywords : aminodiphenylamine * polymerization * FTIR and Raman spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.189, year: 2008

  6. Tunnel magnetoresistance of polymeric chains

    OpenAIRE

    Walczak, Kamil

    2004-01-01

    Coherent spin-dependent electronic transport is investigated in a molecular junction made of polymeric chain attached to ferromagnetic electrodes (Ni and Co, respectively). Molecular system is described by a simple Huckel model, while the coupling to the electrodes is treated through the use of a broad-band theory. The current flowing through the device is calculated within non-equilibrium Green's function approach. It is shown that tunnel magnetoresistance of molecular junction can be quite ...

  7. Alcohol polymerization using electron emission

    International Nuclear Information System (INIS)

    We report a means of instantaneous alcohol polymerization using electron emission at room temperature. We selected 1-butanol as a source of alcohol polymer. A 1-butanol molecule has a simple molecular structure and is a good candidate for analyzing reaction mechanisms. Direct electron emission onto the surface of volatile 1-butanol prevented intense discharge and gently composed 1-butanol-polymer at room temperature in air. The strategy enabled exciting liquids and instantaneously composing new materials at room temperature

  8. Polymeric Microspheres for Medical Applications

    Directory of Open Access Journals (Sweden)

    Ketie Saralidze

    2010-06-01

    Full Text Available Synthetic polymeric microspheres find application in a wide range of medical applications. Among other applications, microspheres are being used as bulking agents, embolic- or drug-delivery particles. The exact composition of the spheres varies with the application and therefore a large array of materials has been used to produce microspheres. In this review, the relation between microsphere synthesis and application is discussed for a number of microspheres that are used for different treatment strategies.

  9. Effects of high-energy electron radiation on polypropylene dielectric

    International Nuclear Information System (INIS)

    Polypropylene, a polymeric materials widely used as the main dielectric in many high-voltage components such as capacitors and cables, was exposed to electron irradiation in air at room temperature. The 25.4-μm-thick dry polypropylene films were irradiated to different doses up to 108 rads with electron beam having energies of 0.5, 1.0, and 1.5 MeV. Monoisopropyl biphenyl (MIPB)-impregnated polypropylene films were also exposed to 1-MeV electron beam to doses up to 108 rads and the post-irradiation effects on the electrical, mechanical, and morphological and chemical properties of the films were evaluated. The electrical properties included the AC, DC and pulsed breakdown strengths, dielectric constant, dissipation factor, conductivity, and pulsed life-endurance. The mechanical properties comprised the Young's modulus, elongation-at-break, tensile strength, complex modulus, and mechanical loss. Finally, the morphological and chemical diagnoses carried out included surface morphology, elemental analysis, crystallinity changes, and identification of newly formed bonds and degree of oxidation. The results obtained indicate that the dry polypropylene films started to exhibit degradation at doses as low as 106 rads. The properties that were mostly affected included the film's tensile properties, pulsed life, dissipation factor, and electrical conductivity

  10. Exploring release and recovery of nanomaterials from commercial polymeric nanocomposites

    International Nuclear Information System (INIS)

    Much concern has been raised about the risks associated with the broad use of polymers containing nanomaterials. Much is known about degradation and aging of polymers and nanomaterials independently, but very few studies have been done in order to understand degradation of polymeric nanocomposites containing nanomaterials and the fate of these nanomaterials, which may occur in suffering many processes such as migration, release and physicochemical modifications. Throughout the UE funded FP7 project NANOPOLYTOX, studies on the migration, release and alteration of mechanical properties of commercial nanocomposites due to ageing and weathering have been performed along with studies on the feasibility of recovery and recycling of the nanomaterials. The project includes the use as model nanocomposites of Polyamide-6 (PA), Polypropylene (PP) and Ethyl Vinyl Acetate (EVA) as polymeric matrix filled with a 3% in mass of a set of selected broadly used nanomaterials; from inorganic metal oxides nanoparticles (SiO2, TiO2 and ZnO) to multi-walled carbon nanotubes (MWCNT) and Nanoclays. These model nanocomposites were then treated under accelerated ageing conditions in climatic chamber. To determine the degree of degradation of the whole nanocomposite and possible processes of migration, release and modification of the nanofillers, nanocomposites were characterized by different techniques. Additionally, recovery of the nanomaterials fro m the polymeric matrix was addressed, being successfully achieved for PA and PP based nanocomposites. In the case of PA, dissolution of the polymeric matrix using formic acid and further centrifugation steps was the chosen approach, while for PP based nanocomposites calcination was performed.

  11. Organic Dielectrics Influence the Crystallographic Structure of Pentacene Thin Films

    International Nuclear Information System (INIS)

    Full text: X-ray diffraction as well as atomic force microscopy experiments have been performed to investigate thin films of pentacene. The films were deposited on thermally grown SiO2 pre-covered by different organic layers. Modifying substrates that the substrate pre-treatments have a strong impact on the performance of the device as well as on the growth of the active layer. However, there are few reports about the influence on the crystalline properties of pentacene. In this work three different systems have been investigated. For one sample series vacuum deposited polymeric Parylene C - with varying thicknesses - was used as the dielectric layer. A second series of dielectric layers was prepared by spin coating a photoreactive polymer (PBHND [poly(bicyclo[2.2.1]hept-5-ene-2,3-(2- nitrobenzyl)dicarboxylate)]) onto the wafer. Subsequently the samples were exposed to UV-light for different time spans. For the third class of systems, a self assembled film of T-SC/SA [4-(2-(trichlorosilyl)ethyl)benzene-1-sulfonyl chloride (TSC), 30% sulfonic acid T-SA] was used to modify the SiOx surface. From the obtained x-ray data we find that the investigated pentacene films are polymorphic and consist of the two commonly observed crystal phases, namely the thin film phase and the Campbell phase. On weakly interacting substrates, these phases are typically oriented with their (001) lattice planes parallel to the substrate surface. Yet in the present investigation it is found that for some dielectric layers the (001) planes of the thin film phase are tilted approximately 3o and of the Campbell phase about 10o with respect to the substrate surface. These small deviations in the structure have a large influence to the in-plane diffraction patterns. Therefore, the changes in the patterns can be unambiguously attributed to the change of preferred orientation. (author)

  12. Dielectric barrier discharges in analytical chemistry.

    Science.gov (United States)

    Meyer, C; Müller, S; Gurevich, E L; Franzke, J

    2011-06-21

    The present review reflects the importance of dielectric barrier discharges in analytical chemistry. Special about this discharge is-and in contrast to usual discharges with direct current-that the plasma is separated from one or two electrodes by a dielectric barrier. This gives rise to two main features of the dielectric barrier discharges; it can serve as dissociation and excitation device and as ionization mechanism, respectively. The article portrays the various application fields for dielectric barrier discharges in analytical chemistry, for example the use for elemental detection with optical spectrometry or as ionization source for mass spectrometry. Besides the introduction of different kinds of dielectric barrier discharges used for analytical chemistry from the literature, a clear and concise classification of dielectric barrier discharges into capacitively coupled discharges is provided followed by an overview about the characteristics of a dielectric barrier discharge concerning discharge properties and the ignition mechanism. PMID:21562672

  13. Two-phase mixed media dielectric with macro dielectric beads for enhancing resistivity and breakdown strength

    Science.gov (United States)

    Falabella, Steven; Meyer, Glenn A; Tang, Vincent; Guethlein, Gary

    2014-06-10

    A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.

  14. Structural basis of reverse nucleotide polymerization

    OpenAIRE

    Nakamura, Akiyoshi; Nemoto, Taiki; Heinemann, Ilka U.; Yamashita, Keitaro; Sonoda, Tomoyo; Komoda, Keisuke; Tanaka, Isao; Söll, Dieter; Yao, Min

    2013-01-01

    Template-dependent RNA and DNA polymerization is a vital reaction in the cell and is believed to occur exclusively in the forward direction (5′-3′), which poses significant challenges to the cell in, for example, lagging strand synthesis. Although cells are mostly limited to unidirectional polymerization, we find that reverse polymerization is structurally and chemically possible utilizing the same structural core, the conserved palm domain of canonical polymerases. The structure of a unique ...

  15. Stimulation of Actin Polymerization by Filament Severing

    OpenAIRE

    Carlsson, A E

    2005-01-01

    The extent and dynamics of actin polymerization in solution are calculated as functions of the filament severing rate, using a simple model of in vitro polymerization. The model is solved by both analytic theory and stochastic-growth simulation. The results show that severing essentially always enhances actin polymerization by freeing up barbed ends, if barbed-end cappers are present. Severing has much weaker effects if only pointed-end cappers are present. In the early stages of polymerizati...

  16. Fluidized bed reactor for catalytic olefin polymerization

    OpenAIRE

    Meier, Gerhardus Bernardus

    2000-01-01

    Due to the continuous improvement of catalysts and processes, polyolefins have become one of the most important plastics in the world. Polyolefins can be produced at low costs with a variety of end-use properties. Nowadays, the most important propylene polymerization processes are executed in the liquid or the gas phase or a combination of both. In contrast to propylene polymerizations in slurry phase, only a few studies have been published concerning gas or liquid phase polymerization. Espec...

  17. Radiation polymerization of allyl derivatives of glycerin

    International Nuclear Information System (INIS)

    Radiation polymerization of 1 allyloxi-3-(chlorine)-alkoxipropanol-2, 1-cro otoxy-3=ethyloxypropanol-2, 1-allylamino-3-amyloxypropanol-2, 1-butoxy-2-allyloxi-3-chlorpropane has been carried out. Some kinetic character ristics of the polymerization process have been obtained. A dependence of the polymerization rate on exposure doze rate, on the persence of modifier (orthopho osphoric acid) and its ratio to the manometer has been studied

  18. Optomechanics of Levitated Dielectric Particles

    CERN Document Server

    Yin, Zhang-qi; Li, Tongcang

    2013-01-01

    We review recent works on optomechanics of optically trapped microspheres and nanoparticles in vacuum, which provide an ideal system for studying macroscopic quantum mechanics and ultrasensitive force detection. An optically trapped particle in vacuum has an ultrahigh mechanical quality factor as it is well-isolated from the thermal environment. Its oscillation frequency can be tuned in real time by changing the power of the trapping laser. Furthermore, an optically trapped particle in vacuum may rotate freely, a unique property that does not exist in clamped mechanical oscillators. In this review, we will introduce the current status of optical trapping of dielectric particles in air and vacuum, Brownian motion of an optically trapped particle at room temperature, Feedback cooling and cavity cooling of the Brownian motion. We will also discuss about using optically trapped dielectric particles for studying macroscopic quantum mechanics and ultrasensitive force detection. Applications range from creating macr...

  19. Applications of dielectric elastomer actuators

    Science.gov (United States)

    Pelrine, Ron; Sommer-Larsen, Peter; Kornbluh, Roy D.; Heydt, Richard; Kofod, Guggi; Pei, Qibing; Gravesen, Peter

    2001-07-01

    Dielectric elastomer actuators, based on the field-induced deformation of elastomeric polymers with compliant electrodes, can produce a large strain response, combined with a fast response time and high electromechanical efficiency. This unique performance, combined with other factors such as low cost, suggests many potential applications, a wide range of which are under investigation. Applications that effectively exploit the properties of dielectric elastomers include artificial muscle actuators for robots; low-cost, lightweight linear actuators; solid- state optical devices; diaphragm actuators for pumps and smart skins; acoustic actuators; and rotary motors. Issues that may ultimately determine the success or failure of the actuation technology for specific applications include the durability of the actuator, the performance of the actuator under load, operating voltage and power requirements, and electronic driving circuitry, to name a few.

  20. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics

    Science.gov (United States)

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-01-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as “degradation inhibitor” for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas. PMID:27338622

  1. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics.

    Science.gov (United States)

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-01-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as "degradation inhibitor" for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas. PMID:27338622

  2. Computational studies of polymeric systems

    Science.gov (United States)

    Carrillo, Jan-Michael Y.

    Polymeric systems involving polyelectrolytes in surfaces and interfaces, semiflexible polyelectrolytes and biopolymers in solution, complex polymeric systems that had applications in nanotechnology were modeled using coarse grained molecular dynamics simulation. In the area of polyelectrolytes in surfaces and interfaces, the phenomena of polyelectrolyte adsorption at oppositely charge surface was investigated. Simulations found that short range van der Waals interaction was a major factor in determining morphology and thickness of the adsorbed layer. Hydrophobic polyelectrolytes adsorbed in hydrophobic surfaces tend to be the most effective in forming multi-layers because short range attraction enhances the adsorption process. Adsorbed polyelectrolytes could move freely along the surface which was in contrast to polyelectrolyte brushes. The morphologies of hydrophobic polyelectrolyte brushes were investigated and simulations found that brushes had different morphologies depending on the strength of the short range monomer-monomer attraction, electrostatic interaction and counterion condensation. Planar polyelectrolyte brushes formed: (1) vertically oriented cylindrical aggregates, (2) maze-like aggregate structures, or (3) thin polymeric layer covering a substrate. While, the spherical polyelectrolyte brushes could be in any of the previous morphologies or be in a micelle-like conformation with a dense core and charged corona. In the area of biopolymers and semiflexible polyelectrolytes in solution, simulations demonstrated that the bending rigidity of these polymers was scale-dependent. The bond-bond correlation function describing a chain's orientational memory could be approximated by a sum of two exponential functions manifesting the existence of the two characteristic length scales. The existence of the two length scales challenged the current practice of describing chain stretching experiments using a single length scale. In the field of nanotechnology

  3. Template polymerization of nucleotide analogues

    Science.gov (United States)

    Orgel, L. E.

    1991-01-01

    Recent work on the template-directed reactions of the natural D-nucleotides has made it clear that l-nucleotides and nucleotide-like derivatives of other sugars would strongly inhibit the formation of long oligonucleotides. Consequently, attention is focusing on molecules simpler than nucleotides that might have acted as monomers of an information transfer system. We have begun a general exploration of the template directed reactions of diverse peptide analogues. I will present work by Dr. Taifeng Wu on oxidative oligomerization of phosphorothioates and of Dr. Mary Tohidi on the cyclic polymerization of nucleoside and related cyclic pyrophosphates.

  4. Marketing NASA Langley Polymeric Materials

    Science.gov (United States)

    Flynn, Diane M.

    1995-01-01

    A marketing tool was created to expand the knowledge of LaRC developed polymeric materials, in order to facilitate the technology transfer process and increase technology commercialization awareness among a non-technical audience. The created brochure features four materials, LaRC-CP, LaRC-RP46, LaRC-SI, and LaRC-IA, and highlights their competitive strengths in potential commercial applications. Excellent opportunities exist in the $40 million per year microelectronics market and the $6 billion adhesives market. It is hoped that the created brochure will generate inquiries regarding the use of the above materials in markets such as these.

  5. Dielectric Relaxation of Hexadeutero Dimethylsulfoxide

    Science.gov (United States)

    Betting, H.; Stockhausen, M.

    1999-11-01

    The dielectric relaxation parameters of the title substance (DMSO-d6) in its pure liquid state are determined from meas-urements up to 72 GHz at 20°C in comparison to protonated DMSO. While the relaxation strengths do not differ, the relax-ation time of DMSO-d 6 is significantly longer (21.3 ps) than that of DMSO (19.5 ps).

  6. An investigation into solid dielectrics

    OpenAIRE

    Kleemann, Tobias

    2012-01-01

    Direct measurement techniques for the investigation of electrical processes in solid dielectrics are reviewed and their respective strengths and weaknesses are discussed, particularly the complementary nature of thermally stimulated current measurements. The successful design and construction of a new Thermally Stimulated Discharge Current (TSDC) Spectrometer at the University of Southampton is presented and its correct function validated with experimental measurements of the well known and o...

  7. Electromagnetic flowmeter for dielectric liquids.

    OpenAIRE

    Amare, T.

    1995-01-01

    Experimental investigation and theoretical analysis of an electromagnetic flowmeter designed for use with dielectric liquids has been carried out. An extensive survey of the industrial users of flowmeters has been made, involving the participation of over 47 companies, which provides information about the current industrial use, attitudes and attributes of electromagnetic and other types of flowmeters. The design of the flowmeter is mainly concerned with overcoming the charge n...

  8. Dielectric constant and loss factor measurement of polycarbonate, Makrofol KG using swift heavy ion O5+

    International Nuclear Information System (INIS)

    Swift heavy ion irradiation (SHI) induces modifications in the electrical properties of polycarbonate (PC), Makrofol KG. This enables us to study the dielectric response of pristine and irradiated polymers for a wide range of fluence, temperature and frequency. The results are related to structural changes of the polymer. Actually there exist two kinds of phenomena namely chain scission and endlinking in heavy ion irradiation of polycarbonate at different energy densities. Structural changes are co-related using UV and visible spectrophotometer by measuring the absorbance as a function of wavelength. A plot of dielectric loss versus temperature at 1 kHz reveals two relaxations in the temperature range of 30-140 oC, which may be associated with pre-glass transition (β), glass transition (α), and motion of the polymeric chain. Both the peaks show shifts to the low temperature side with increase of dose.

  9. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    Science.gov (United States)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  10. Dielectric-filled radiofrequency linacs

    International Nuclear Information System (INIS)

    High current, high brightness electron beam accelerators promise to open up dramatic new applications. Linear induction accelerators are currently viewed as the appropriate technology for these applications. A concept by Humphries and Hwang may permit radiofrequency accelerators to fulfill the same functions with greater simplicity and enhanced flexibility. This concept involves the replacement of vacuum rf cavities with dielectric filled ones. Simple analysis indicates that the resonant frequencies are reduced by a factor of (ε0/ε)1/2 while the stored energy is increased by ε/ε0. For a high dielectric constant like water, this factor can approach 80. A series of numerical calculations of simple pill-box cavities was performed. Eigenfunctions and resonant frequencies for a full system configuration, including dielectric material, vacuum beamline, and a ceramic window separating the two have been computed. These calculations are compared with the results of a small experimental cavity which have been constructed and operated. Low power tests show excellent agreement. (author). 4 figs., 8 refs

  11. Dielectric decrement effects in electrokinetics

    Science.gov (United States)

    Figliuzzi, Bruno; Chan, Wai Hong Ronald; Buie, Cullen; Moran, Jeffrey

    2015-11-01

    Understanding the nonlinear phenomena that occur in the electric double layer (EDL) that forms at charged surfaces is a key issue in electrokinetics. In recent studies, Nakayama and Andelman [J. Chem. Physics 2015] Hatlo et al. [EPL 2012], and Zhao and Zhai [JFM 2013] demonstrated that dielectric decrement significantly influences the ionic concentration in the electric double layer (EDL) at high zeta potential, leading to the formation of a condensed layer near the particle's surface. In this presentation, we apply the dielectric decrement model to study two archetypal problems in electrokinetics, namely the electrophoresis of particles with fixed surface charges and the electrophoresis of ideally polarizable particles. Our aim is to rely on numerical simulations to incorporate nonlinear effects including crowding effects due to the finite size of ions, dielectric decrement in the EDL, surface conduction, concentration polarization and advection in the bulk solution. In parallel, we derive a simplified composite layer model that enables us to obtain analytical estimates of the physical quantities involved in the physical description of the problem.

  12. Investigation of the Dielectric Strength of Syntactic Foam at 77 K under DC Stress

    Science.gov (United States)

    Winkel, D.; Puffer, R.; Schnettler, A.

    2014-05-01

    Liquid nitrogen (LN2) based electrical insulation systems for superconducting equipment of electrical power distribution networks are state of the art. Since LN2 is a cryogenic liquid it has some disadvantages when used as insulation. This paper deals with syntactic foam as an alternative insulation system for superconducting apparatus. Syntactic foam is a composite material consisting of a polymeric matrix and embedded hollow microspheres with diameters of several 10 μp?. As hollow microspheres are gas-filled, using those as filling material features significant reductions of the relative permittivity and of the thermal contraction due to cooling the material to liquid nitrogen temperature (LNT, T = 77 K). In this study both an epoxy resin (ER) and an unsaturated polyester resin (UPR) serve as matrix material. The hollow microspheres used in this investigation are made of untreated and silanized glass. The results of measurements of the dielectric DC strength show, that the dielectric strength of all investigated syntactic foam compositions are significantly higher at LNT compared to ambient temperature (AT). Furthermore, the effect of a higher dielectric strength of syntactic foam with silanized glass spheres at ambient temperature vanishes at LNT. Hence, the dielectric strength at LNT is unaffected by silanization of glass microspheres.

  13. Synthesis, transport and dielectric properties of polyaniline/Co3O4 composites

    Indian Academy of Sciences (India)

    Shantala D Patil; S C Raghavendra; M Revansiddappa; P Narsimha; M V N Ambika Prasad

    2007-04-01

    Conducting polyaniline/cobaltous oxide composites have been synthesized using in situ deposition technique by placing fine graded/cobaltous oxide in polymerization mixture of aniline. The a.c. conductivity and dielectric properties are studied by sandwiching the pellets of these composites between the silver electrodes. It is observed that the values of conductivities increase up to 30 wt% of cobaltous oxide in polyaniline and decrease thereafter. Initial increment in conductivity is due to extended chain length of polyaniline where polarons possess sufficient energy to hop between favourable sites. Beyond 30 wt% of cobaltous oxide in polyaniline, blocking of charge carriers takes place reducing the conductivity values. It can be noted that the value of dielectric constant increases up to 10 wt% of cobaltous oxide. Thereafter, it decreases up to 30 wt% of cobaltous oxide and again increases up to 40 wt% of cobaltous oxide and decreases thereafter. The observed behaviour is attributed to the variation of a.c. conductivity. And it is observed that the dielectric loss increases up to 10 wt% of cobaltous oxide in polyaniline, decreases to a lower value of 20 wt% of cobaltous oxide and increases to 35 wt% and thereafter decreases. These values go in accordance with the values of dielectric constant. The results obtained for these composites are of greater scientific and technological importance.

  14. Water induced evolution of dielectric and micro-structural properties of rice starch

    OpenAIRE

    F. Starzyk; Chrzanowska, A.; W. Łużny; M. Śniechowski

    2009-01-01

    Purpose: The purpose of this paper was to record and correlate mass (m) changes of population of rice starch micro-granules and their effective dielectric permittivity(ε′), as well as X-ray diffraction (XRD) changes observed in this system during humidification.Design/methodology/approach: Changes of mass of bio-polymeric-granular sample occurring during its exposition on saturated water vapour at room temperature, was recorded in the time. The ε′ evolution was recorded by means of fringe-fie...

  15. Nanomechanical testing of polymeric nanofibers

    Science.gov (United States)

    Tan, E. P. S.; Lim, C. T.

    2005-04-01

    Biodegradable polymeric nanofibrous scaffold comprises individual nanofibers where their stiffnesses can promote or undermine the various cellular functions as well as structural integrity of the scaffold. As such, there is a need to investigate the nanomechanical properties of these individual nanofibers. However, conducting mechanical tests of individual fibers at the nanometer scale can pose great challenges and difficulties. Here, we present novel techniques to perform nanomechanical testing of individual polymeric nanofibers. For demonstration of the nano tensile tests, polycaprolactone (PCL) nanofibers were produced via electrospinning. These fibers were deposited across two parallel edges of a cardboard frame so that a single nanofiber can be isolated for tensile test using a nano tensile tester. For nanoscale three-point bend test, a Poly (L-lactic acid) (PLLA) nanofiber was suspended across a microsized groove etched on a silicon wafer. An atomic force microscope (AFM) tip was then used to apply a point load on the mid-span of the suspended fiber. Beam bending theory was then used to calculate the elastic modulus of the nanofiber. For nanoindentation test, a PLLA nanofiber was deposited on a mica substrate and an AFM tip used to indent the nanofiber. Modified Hertz theory for normal contact was then used to evaluate the elastic modulus of the nanofiber.

  16. Thermally stable, low dielectric polyquinolines for aerospace and electronics applications

    Science.gov (United States)

    Hendricks, Neil H.; Marrocco, Matthew L.; Stoakley, Diane M.; St. Clair, Anne K.

    1990-01-01

    Four new high molecular weight, linear chain polyquinolines have been synthesized and fabricated into high quality free standing films. These polymers are characterized by moderate to high glass transition temperatures, excellent thermal and thermooxidative stability, extremely low dielectric constants and good planarizing characteristics. The polymers absorb very low quantities of moisture. As a consequence, the dielectric constant of one new polyquinoline has been shown to be quite insensitive to exposure to warm/wet conditions. Isothermal aging of one new derivative in air has been carried out at elevated temperatures (250 C to 345 C). The results demonstrate truly outstanding thermooxidative stability. Additional characterizations include molecular weight determinations, solubilities and film-forming characteristics, density measurements, and UV-Vis spectroscopy. The data acquired to date suggest that the polymers may find use as refractive films and coatings and as interlevel planarizers in microelectronics applications.

  17. Polymeric Materials Review on Oxidation, Stabilization and Evaluation using CL and DSC Methods

    CERN Document Server

    Ilie, Sorin; CERN. Geneva. TE Department

    2009-01-01

    Within TE - VSC Group, the Chemistry Laboratory actually works on the project entitled “Studies of Radiation Induced Aging Effects in Polymeric Cable Insulators”. The aim of the project is the characterization and the evaluation of the aging effects mainly induced by ionizing radiations on the various polymeric materials in cables structure. It is expected, using the accumulated data, to foresee the life-time of these materials in the specific CERN accelerator systems and, also, to assure an acceptance quality control of the supplied cables in CERN.

  18. Dielectric behavior of semiconductors at microwave frequencies

    Science.gov (United States)

    Dahiya, Jai N.

    1992-01-01

    A cylindrical microwave resonant cavity in TE(011) (Transverse Electric) mode is used to study the dielectric relaxation in germanium and silicon. The samples of these semiconductors are used to perturb the electric field in the cavity, and Slater's perturbation equations are used to calculate the real and imaginary parts of the dielectric constant. The dielectric loss of germanium and silicon is studied at different temperatures, and Debye's equations are used to calculate the relaxation time at these temperatures.

  19. Test results of a prototype dielectric microcalorimeter

    Science.gov (United States)

    Pfafman, T. E.; Silver, E.; Labov, S.; Beeman, J.; Goulding, F.; Hansen, W.; Landis, D.; Madden, N.

    1990-01-01

    The initial development work on a dielectric microcalorimeter is presented. It focuses on the dielectric properties of the ferroelectric material KTa(1-x)Nb(x)O3 (KTN). Measurements of the temperature dependent dielectric constant are given together with the first alpha particle detection results from a prototype composite microcalorimeter operating at 1.3 K. A nonthermal mechanism for detecting 6 MeV alpha particles in a monolithic KTN sample is also reported.

  20. Terahertz-frequency dielectric response of liquids

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Møller, Uffe; Cooke, David

    -induced dipole moments. In the polar liquid water the fastest relaxational dynamics is found at terahertz frequencies, just below the first intermolecular vibrational and librational modes. In this presentation we will discuss optical terahertz spectroscopic techniques for measurement of the full dielectric...... function of liquids at terahertz frequencies. We will review the current understanding of the high-frequency dielectric spectrum of water, and discuss the relation between the dielectric spectrum and the thermodynamic properties of certain aqueous solutions....

  1. Graphene-Dielectric Integration for Graphene Transistors

    OpenAIRE

    Liao, Lei; Duan, Xiangfeng

    2010-01-01

    Graphene is emerging as an interesting electronic material for future electronics due to its exceptionally high carrier mobility and single-atomic thickness. Graphene-dielectric integration is of critical importance for the development of graphene transistors and a new generation of graphene based electronics. Deposition of dielectric materials onto graphene is of significant challenge due to the intrinsic material incompatibility between pristine graphene and dielectric oxide materials. Here...

  2. POLYMERIC NANOPARTICLES FROM SUPERCRITICAL CO2 MICROEMULSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Wei-jun Ye; Jason S. Keiper; Joseph M. DeSimone

    2006-01-01

    Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant (bis-[2-(F-hexyl)ethyl]phosphate sodium), water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N'-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 (w/c) microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2'-azo-bisisobutyronitrile (AIBN), cross-linked poly(acryloxyethyltrimethyl ammonium chloride) particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained.

  3. Dielectric Resonator Metasurface for Dispersion Engineering

    CERN Document Server

    Achouri, Karim; Gupta, Shulabh; Rmili, Hatem; Caloz, Christophe

    2016-01-01

    We introduce a practical dielectric metasurface design for microwave frequencies. The metasurface is made of an array of dielectric resonators held together by dielectric connections thus avoiding the need of a mechanical support in the form of a dielectric slab and the spurious multiple reflections that such a slab would generate. The proposed design can be used either for broadband metasurface applications or monochromatic wave transformations. The capabilities of the concept to manipulate the transmission phase and amplitude of the metasurface are supported by numerical and experimental results. Finally, a half-wave plate and a quarter-wave plate have been realized with the proposed concept.

  4. Spring-loaded polymeric gel actuators

    Science.gov (United States)

    Shahinpoor, M.

    1995-02-14

    Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications. 5 figs.

  5. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric materialis described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney...

  6. Ion exchange behaviour of polymeric zirconium cations

    International Nuclear Information System (INIS)

    Polymeric zirconium cations formed in weakly acid solutions (pH2) are taken up strongly into macroporous cation exchange resins, while uptake into normal cation exchange resins (pore diameter about 1 nm) is low. Macroporous cation exchange resins loaded with polymeric Zr cations are shown to function as ligand exchange sorbents. (Authors)

  7. Clinical and Experimental Evaluation of the Effectiveness of «Soft-Start» Polymerization in Dental Composite Restoration

    Directory of Open Access Journals (Sweden)

    Timur V. Melkumyan, PhD, ScD

    2012-09-01

    Full Text Available The clinical and experimental efficiency of the soft-start polymerization technique in composite restorations was studied. In this study, 57 patients between 30 and 44 years of age with secondary caries had 158 restorations done using the photo-composite material Filtek Z250. The restorations performed were distinguished into two groups, the basis of the photo-polymerization method of employed (conventional polymerization technique and «soft-start» polymerization technique. The objects of the study also included the specimens of 18 extracted teeth. The analysis of the data indicates that employing the «soft-start» polymerization technique provides better integration of the composite material to the hard tissues of the tooth. This conclusion was best demonstrated in cases where the dentin was a connecting link in the chain «substrate-hybrid layer-composite».

  8. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on dipolar copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede; Hvilsted, Søren; Skov, Anne Ladegaard

    2014-01-01

    Dielectric elastomers (DES) are a promising new transducer technology, but high driving voltages limit their current commercial potential. One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permi...

  9. Organic thin film transistors with polymer brush gate dielectrics synthesized by atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Pinto, J.C.; Whiting, G.L.; Khodabakhsh, S.;

    2008-01-01

    Low operating voltage is an important requirement that must be met for industrial adoption of organic field-effect transistors (OFETs). We report here solution fabricated polymer brush gate insulators with good uniformity, low surface roughness and high capacitance. These ultra thin polymer films...

  10. Fluid Effects in Polymers and Polymeric Composites

    CERN Document Server

    Weitsman, Y Jack

    2012-01-01

    Fluid Effects in Polymers and Polymeric Composites, written by the late Dr. Y. Jack Weitsman, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed. The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. While...

  11. Dead Sea Minerals loaded polymeric nanoparticles.

    Science.gov (United States)

    Dessy, Alberto; Kubowicz, Stephan; Alderighi, Michele; Bartoli, Cristina; Piras, Anna Maria; Schmid, Ruth; Chiellini, Federica

    2011-10-15

    Therapeutic properties of Dead Sea Water (DSW) in the treatment of skin diseases such as atopic dermatitis, psoriasis and photo aging UV damaged skin have been well established. DSW is in fact rich in minerals such as calcium, magnesium, sodium, potassium, zinc and strontium which are known to exploit anti-inflammatory effects and to promote skin barrier recovery. In order to develop a Dead Sea Minerals (DSM) based drug delivery system for topical therapy of skin diseases, polymeric nanoparticles based on Poly (maleic anhydride-alt-butyl vinyl ether) 5% grafted with monomethoxy poly(ethyleneglycol) 2000 MW (PEG) and 95% grafted with 2-methoxyethanol (VAM41-PEG) loaded with DSM were prepared by means of a combined miniemulsion/solvent evaporation process. The resulting nanoparticles were characterized in terms of dimension, morphology, biocompatibility, salt content and release. Cytocompatible spherical nanoparticles possessing an average diameter of about 300 nm, a time controlled drug release profile and a high formulation yield were obtained. PMID:21676600

  12. Radiation Polymerization of Acetylene Hydrocarbons. Special Features

    International Nuclear Information System (INIS)

    The synthesis and study of the properties of polymers with conjugated bond systems offers new and extremely promising prospects in the chemistry of high molecular compounds. A high degree of de-localization of p-electrons in the macromolecule is characteristic of such polymer systems. The decrease in the energy excited in the triplet state, just like the diminished ionization potential with large conjugated bonds, conditions the semiconductor and specific magnetic properties of such compounds. In addition, polymer systems with conjugated bonds have proved to be extremely effective stabilizers in the thermo- and photo-oxidation destruction of polymers. The radiation polymerization of acetylene derivatives offers one suitable method of obtaining such polymers and is the only one which ensures that the polymers obtained are free of contamination from initiators at low temperatures. The kinetics of the radiation polymerization of ethynyl benzene and other acetylene derivatives have a number of features typical of ion polymerization quite rare in radical polymerization (speed of polymerization linearly proportional to speed of initiation: very low activation energy; no oxygen inhibition). Nevertheless this polymerization is obviously radical. We reached that conclusion on the basis of a study of polymerization initiation for acetylene hydrocarbons by typical radical initiators - benzoyl peroxide and the dinitrile of azoisobutyric acid. They investigated the kinetic features and mechanism of peroxide decomposition in the presence of acetylene hydrocarbons (e.g. ethynyl benzene, deutero-ethynyl benzene and phenylpropyne). The kinetics of radiation co-polymerization of ethynyl benzene with different vinyl monomers and the composition of copolymers in different initial mixtures were also studied. These data and the results of a study of the kinetics of inhibited ethynyl benzene polymerization (benzoquinone initiator) indicate a small reactivity capacity of the ethynyl

  13. Dielectric strength of parylene HT

    International Nuclear Information System (INIS)

    The dielectric strength of parylene HT (PA-HT) films was studied at room temperature in a wide thickness range from 500 nm to 50 μm and was correlated with nano- and microstructure analyses. X-ray diffraction and polarized optical microscopy have revealed an enhancement of crystallization and spherulites development, respectively, with increasing the material thickness (d). Moreover, a critical thickness dC (between 5 and 10 μm) is identified corresponding to the beginning of spherulite developments in the films. Two distinct behaviors of the dielectric strength (FB) appear in the thickness range. For d ≥ dC, PA-HT films exhibit a decrease in the breakdown field following a negative slope (FB ∼ d−0.4), while for d C, it increases with increasing the thickness (FB ∼ d0.3). An optimal thickness doptim ∼ 5 μm corresponding to a maximum dielectric strength (FB ∼ 10 MV/cm) is obtained. A model of spherulite development in PA-HT films with increasing the thickness is proposed. The decrease in FB above dC is explained by the spherulites development, whereas its increase below dC is induced by the crystallites growth. An annealing of the material shows both an enhancement of FB and an increase of the crystallites and spherulites dimensions, whatever the thickness. The breakdown field becomes thickness-independent below dC showing a strong influence of the nano-scale structural parameters. On the contrary, both nano- and micro-scale structural parameters appear as influent on FB for d ≥ dC

  14. Dielectric strength of parylene HT

    Energy Technology Data Exchange (ETDEWEB)

    Diaham, S., E-mail: sombel.diaham@laplace.univ-tlse.fr; Bechara, M.; Locatelli, M.-L.; Khazaka, R. [Université de Toulouse, UPS, INPT, LAPLACE, 118 route de Narbonne-Bât. 3R3, F-31062 Toulouse Cedex 9 (France); CNRS, LAPLACE, F-31062 Toulouse (France); Tenailleau, C. [Université de Toulouse, UPS, Laboratoire CIRIMAT/LCMIE, 118 route de Narbonne-Bât. 2R1, F-31062 Toulouse Cedex 9 (France); Kumar, R. [Speciality Coating Systems, Inc. (SCS), Cookson Electronics, 7645 Woodland Drive, Indianapolis, Indiana 46278 (United States)

    2014-02-07

    The dielectric strength of parylene HT (PA-HT) films was studied at room temperature in a wide thickness range from 500 nm to 50 μm and was correlated with nano- and microstructure analyses. X-ray diffraction and polarized optical microscopy have revealed an enhancement of crystallization and spherulites development, respectively, with increasing the material thickness (d). Moreover, a critical thickness d{sub C} (between 5 and 10 μm) is identified corresponding to the beginning of spherulite developments in the films. Two distinct behaviors of the dielectric strength (F{sub B}) appear in the thickness range. For d ≥ d{sub C}, PA-HT films exhibit a decrease in the breakdown field following a negative slope (F{sub B} ∼ d{sup −0.4}), while for d < d{sub C}, it increases with increasing the thickness (F{sub B} ∼ d{sup 0.3}). An optimal thickness d{sub optim} ∼ 5 μm corresponding to a maximum dielectric strength (F{sub B} ∼ 10 MV/cm) is obtained. A model of spherulite development in PA-HT films with increasing the thickness is proposed. The decrease in F{sub B} above d{sub C} is explained by the spherulites development, whereas its increase below d{sub C} is induced by the crystallites growth. An annealing of the material shows both an enhancement of F{sub B} and an increase of the crystallites and spherulites dimensions, whatever the thickness. The breakdown field becomes thickness-independent below d{sub C} showing a strong influence of the nano-scale structural parameters. On the contrary, both nano- and micro-scale structural parameters appear as influent on F{sub B} for d ≥ d{sub C}.

  15. Environment-Responsive Polymeric Hydrogels

    Institute of Scientific and Technical Information of China (English)

    Zhn X. X.; M. Nichifor; Lin H.Y.; D. Avoce

    2004-01-01

    Some polymers may respond by changing their physico-chemical perperties when the environmental conditions such as pH, temperature and ionic strength are varied. For example,thermosensentive polymers can exhibit a sharp change in solubility in a solvent such as water at a certain temperature known as the lower critical solution temperature (LCST). The responsiveness of the polymeric materials has important technological implications since they can be employed for various applications. The responsiveness of such polymers can be varied by means of copolymerization, chemical modification of the polymer, or the addition of reagents into the solutions. It is interesting and important to tune predictably the responsiveness of the polymers for the different applications. The sensitivity towards the external environment can be modulated by the relative hydrophilicity of the copolymers, hence the chemical structure and composition of the comonomers used.

  16. MESO-STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhong Yang; Jian-hua Rong; Dan Li

    2003-01-01

    Meso-structured (opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods: post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers. A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color, which is important in designing tunable photonic crystals. Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed. The catalytic effect of acid groups inthe templates was emphasized for a preferential formation of TiO2 in the region containing acid groups, which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  17. MESO—STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhongYang; Jian-huaRong; DanLi

    2003-01-01

    Meso-structured(opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods:post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers.A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color,which is important in designing tunable photonic crystals.Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed.The catalytic effect of acid groups in the templates was emphasized for a preferential formation of TiO2 in the region containing acid groups,which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  18. Superbackscattering from single dielectric particles

    Science.gov (United States)

    Liberal, Iñigo; Ederra, Iñigo; Gonzalo, Ramón; Ziolkowski, Richard W.

    2015-07-01

    We demonstrate that superbackscattering responses can be excited in subwavelength dielectric particles with simple geometries. The superbackscattering response arises from the simultaneous, coherent excitation of electric dipole and magnetic quadrupole resonances. Its signature is a superdirective scattering pattern simultaneously pointing towards both the forward and backward directions. The practical implementation of this effect with Tellurium particles operating in the thermal infrared is also addressed. The examples presented reveal that spherical resonators outperform array-based superbackscatterers in terms of the backscattering peak, compact size, robustness against losses and isotropic response.

  19. The Dielectric Properties of Poly

    Science.gov (United States)

    Bello, Alfredo

    The dielectric properties of poly(vinylidene fluoride) (PVF(,2)) are discussed in this work. A review of the literature concerning the five known dielectric relaxations of PVF(,2) is presented and the general theory of dielectric relaxations in polymers is summarized. The real and imaginary parts of the dielectric constant of several samples of PVF(,2) were measured as a function of frequency, temperature and pressure. In the temperature experiment covering the range from 5 K to 380 K at five audio frequencies (100 Hz to 10 KHz), four relaxations were found: (alpha), (beta), (delta) and (epsilon). The (alpha) relaxation at temperatures between 345 and 370 K at 1000 Hz, was found to be dependent on the history and preparation method of the sample and also to have a Debye like behavior. The (beta) relaxation around 250 K at 1000 Hz was found to be related to the glass transition of PVF(,2) and its behavior is parametrized by using the Williams-Landel-Ferry (WLF) model. The (delta) relaxation around 76 K at 1000 Hz was found to be Debye like and associated with the (alpha)-phase of PVF(,2). The (epsilon) relaxation was found in (beta)-phase PVF(,2) at 14.5 K at 1000 Hz. Evidence of the relaxation was found also in (alpha)-phase PVF(,2). In the pressure experiments the (beta) relaxation was studied in the temperature range from 240 to 360 K and at pressures from 0.0001 to 0.6 GPa. The behavior was explained by using the WLF free volume model and comparison between the calculated glass transition temperature parameter in the WLF equation and the experimental peak temperature is made. It was found that even though the WLF equation mathematically describes the (beta) relaxation, the T(,g) parameter does not represent the real transition temperature behavior with pressure. The peak temperature of the (beta) relaxation, was found to be a better guide to the behavior of the real T(,g).

  20. Ferroelectric dielectrics integrated on silicon

    CERN Document Server

    Defay, Emmanuel

    2013-01-01

    This book describes up-to-date technology applied to high-K materials for More Than Moore applications, i.e. microsystems applied to microelectronics core technologies.After detailing the basic thermodynamic theory applied to high-K dielectrics thin films including extrinsic effects, this book emphasizes the specificity of thin films. Deposition and patterning technologies are then presented. A whole chapter is dedicated to the major role played in the field by X-Ray Diffraction characterization, and other characterization techniques are also described such as Radio frequency characterizat

  1. Polymeric materials from renewable resources

    Science.gov (United States)

    Frollini, Elisabete; Rodrigues, Bruno V. M.; da Silva, Cristina G.; Castro, Daniele O.; Ramires, Elaine C.; de Oliveira, Fernando; Santos, Rachel P. O.

    2016-05-01

    The goals of our studies have been the use of renewable raw materials in the preparation of polymeric materials with diversified properties. In this context, lignosulfonate, which is produced in large scale around the world, but not widely used in the production of polymeric materials, was used to replace phenol and polyols in the preparation of phenolic- (Ligno-PH) and polyurethane-type (Ligno-PU) polymers, respectively. These polymers were used to prepare composites reinforced with sisal lignocellulosic fibers. The use of lignosulfonate in the formulation of both types of polymers was beneficial, because in general composites with improved properties, specially impact strength, were obtained. Composites were also prepared from the so called "biopolyethylene" (HDPE), curaua lignocellulosic fiber, and castor oil (CO). All composites HDBPE/CO/Fiber exhibited higher impact strength, when compared to those of the corresponding HDBPE/Fiber. These results, combined with others (eg SEM images of the fractured surfaces) indicated that, in addition to acting as a plasticizer, this oil may have acted as a compatibilizer of the hydrophilic fiber with the hydrophobic polymer. The set of results indicated that (i) mats with nano (diameter ≤ 100nm) and/or ultrafine (submicron scale) fibers were produced, (ii) hybrid fibers were produced (bio-based mats composites), (iii) cellulosic pulp (CP) and/or lignin (Lig) can be combined with PET matrices to control properties such as stiffness and hydrophilicity of the respective mats. Materials with diversified properties were prepared from high content of renewable raw materials, thus fulfilling the proposed targets.

  2. Radiation polymerization of vinylene carbonate

    International Nuclear Information System (INIS)

    The radiation-induced polymerization of vinylene carbonate of 99,97% purity has been investigated. The relationship between conversion and irradiation time is strictly linear, even at the lowest conversions, thus proving that the normal induction period observed for the polymerization of lower-purity vinylene carbonate indeed results from the presence of an inhibitor. Although the identity of the inhibitor has not been established, it has been shown that it is not dichlorovinylene carbonate. An activation energy of 15,1 kJ/mole was calculated for the homopolymerization process. The radiation-induced copolymerization of vinylene carbonate (M1) with isobutyl vinyl ether (M2) has been investigated over the temperature range of 40-80 degrees Celcius. The monomer reactivity ratios r1 and r2 were determined to be 0,118 and 0,148 respectively, and an activation energy of 31,8kJ/mole was calculated for the copolymerization process. The radiation-induced telomerization of vinylene carbonate with carbon tetrachloride has been investigated over a telogen to monomer concentration ratio range of 4 to 20. The rate of formation of the n=1 adduct was found to be independent of monomer concentration, directly proportional to the telogen concentration, and exhibiting a 0,38 order power dependence on the radiation intensity, in general agreement with the derived rate equations. The rate of formation of the n=2 telomer was found to be independent of both monomer and telogen concentrations and radiation intensity, which is not in agreement with the derived rate equations. The first and second chain-transfer coefficients C1 and C2 were determined to be 0,116 and 0,34 respectively, and the activation energies for the formation of the n=1 adduct and n=2 telomer were calculated to be 17,6 and 64,9 kJ/mole respectively

  3. Quantum cascade laser based monitoring of CF2 radical concentration as a diagnostic tool of dielectric etching plasma processes

    International Nuclear Information System (INIS)

    Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF2 radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF2 radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm−1. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ν3 fundamental band of CF2 with the aid of an improved simulation of the line strengths. We found that the CF2 radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing

  4. Bonding of Glass Ceramic and Indirect Composite to Non-aged and Aged Resin Composite

    NARCIS (Netherlands)

    Gresnigt, Marco; Ozcan, Mutlu; Muis, Maarten; Kalk, Warner

    2012-01-01

    Purpose: Since adhesion of the restorative materials to pre-polymerized or aged resin composites presents a challenge to the clinicians, existing restorations are often removed and remade prior to cementation of fixed dental prostheses (FDPs). This study evaluated bond strength of non-aged and aged

  5. A simple method for reducing inevitable dielectric loss in high-permittivity dielectric elastomers

    Science.gov (United States)

    Madsen, F. B.; Yu, L.; Mazurek, P.; Skov, A. L.

    2016-07-01

    Commercial viability of dielectric elastomers (DEs) is currently limited by a few obstacles, including high driving voltages (in the kV range). Driving voltage can be lowered by either decreasing the Young’s modulus or increasing the dielectric permittivity of silicone elastomers, or a combination thereof. A decrease in the Young’s modulus, however, is often accompanied by a loss in mechanical stability, whereas increases in dielectric permittivity are usually followed by a large increase in dielectric loss followed by a decrease in breakdown strength and thereby the lifetime of the DE. A new soft elastomer matrix, with high dielectric permittivity and a low Young’s modulus, aligned with no loss of mechanical stability, was prepared through the use of commercially available chloropropyl-functional silicone oil mixed into a tough commercial liquid silicone rubber silicone elastomer. The addition of chloropropyl-functional silicone oil in concentrations up to 30 phr was found to improve the properties of the silicone elastomer significantly, as dielectric permittivity increased to 4.4, dielectric breakdown increased up to 25% and dielectric losses were reduced. The chloropropyl-functional silicone oil also decreased the dielectric losses of an elastomer containing dielectric permittivity-enhancing TiO2 fillers. Commercially available chloropropyl-functional silicone oil thus constitutes a facile method for improved silicone DEs, with very low dielectric losses.

  6. All-dielectric metasurface for optical focusing

    NARCIS (Netherlands)

    Pisano, E.; Silvestri, F.; Gerini, G.; Lancellotti, V.; Galdi, V.

    2015-01-01

    We propose the design of a dielectric flat lens for visible wavelengths, capable of efficiently focus the incident field at a given distance. Our approach relies on the recently proposed exploitation of high-index dielectric resonators with spectrally overlapping electric and magnetic dipole resonan

  7. Fullerene derivatives with increased dielectric constants

    NARCIS (Netherlands)

    Jahani, Fatemeh; Torabi, Solmaz; Chiechi, Ryan C; Koster, L Jan Anton; Hummelen, Jan C

    2014-01-01

    The invention of new organic materials with high dielectric constants is of extreme importance for the development of organic-based devices such as organic solar cells. We report on a synthetic way to increase the dielectric constant of fullerene derivatives. It is demonstrated that introducing trie

  8. Microwave dielectric method for moisture sensing almonds

    Science.gov (United States)

    A dielectric –based method was developed for rapid and nondestructive determination of moisture content in almond kernels independent of bulk density from measurement of their dielectric properties at a single microwave frequency. Calibration equations for moisture determination with temperature com...

  9. Torus-like Dielectric D2-brane

    OpenAIRE

    Hyakutake, Yoshifumi

    2001-01-01

    We find new solutions corresponding to torus-like generalization of dielectric D2-brane from the viewpoint of D2-brane action and N D0-branes one. These are meta-stable and would decay to the spherical dielectric D2-brane.

  10. Microwave device for liquid dielectrics diagnostics

    OpenAIRE

    Safonov, V. V.

    2010-01-01

    It is developed a method for measuring of dielectric permittivity of liquid dielectrics. High accuracy and reliability of the method is provided by definite hardware realization; it is used resonance-bridge method; to provide high stability of measuring SHF signal frequency there is used self-excited oscillator on a basis of active running wave resonator.

  11. Microscopic resolution broadband dielectric spectroscopy

    International Nuclear Information System (INIS)

    Results are presented for a non-contact measurement system capable of micron level spatial resolution. It utilises the novel electric potential sensor (EPS) technology, invented at Sussex, to image the electric field above a simple composite dielectric material. EP sensors may be regarded as analogous to a magnetometer and require no adjustments or offsets during either setup or use. The sample consists of a standard glass/epoxy FR4 circuit board, with linear defects machined into the surface by a PCB milling machine. The sample is excited with an a.c. signal over a range of frequencies from 10 kHz to 10 MHz, from the reverse side, by placing it on a conducting sheet connected to the source. The single sensor is raster scanned over the surface at a constant working distance, consistent with the spatial resolution, in order to build up an image of the electric field, with respect to the reference potential. The results demonstrate that both the surface defects and the internal dielectric variations within the composite may be imaged in this way, with good contrast being observed between the glass mat and the epoxy resin.

  12. Dielectric bow-tie nanocavity.

    Science.gov (United States)

    Lu, Qijing; Shu, Fang-Jie; Zou, Chang-Ling

    2013-12-15

    We propose a novel dielectric bow-tie (DBT) nanocavity consisting of two opposing tip-to-tip triangle semiconductor nanowires, whose end faces are coated by silver nanofilms. Based on the advantages of the dielectric slot and tip structures, and the high reflectivity of the silver mirror, light can be confined in this nanocavity with low loss. We demonstrate that at 4.5 K (300 K) around the resonance wavelength of 1550 nm, the mode excited in this nanocavity has a deep subwavelength mode volume of 2.8×10(-4) μm³ and a high quality factor of 4.9×10(4) (401.3), corresponding to an ultrahigh Purcell factor of 1.6×10(7) (1.36×10(5)). This DBT nanocavity may find applications for integrated nanophotonic circuits, such as high-efficiency single photon sources, thresholdless nanolasers, and strong coupling in cavity quantum electrodynamics experiments. PMID:24322245

  13. Dielectric Track Detector fuel motion monitor system

    International Nuclear Information System (INIS)

    The fuel motion monitor system described is one of the systems being developed for use in the upgraded Sandia ACPR. Like the hodoscope, this system will image fast neutrons from the test fuel element--but there the similarity to the hodoscope ends, because this system will use Dielectric Track Detectors (DTD's) for both neutron detection and recording. Kimfoil is a commercial polycarbonate film that is used as a capacitor dielectric. It is just one example of a Dielectric Track Detector. When a DTD is struck by an energetic and heavy ion, the ion produces damage along its path. If the dielectric is then etched, the damaged track enlarges to form a crater. These craters are then easily visible with an optical microscope. These dielectrics have several properties that make them ideal for use in a reactor environment. First of all, they are completely insensitive to any of the background radiations to which they can be exposed in that environment

  14. Method for forming polymerized microfluidic devices

    Science.gov (United States)

    Sommer, Gregory J.; Hatch, Anson V.; Wang, Ying-Chih; Singh, Anup K.; Renzi, Ronald F.; Claudnic, Mark R.

    2013-03-12

    Methods for making a microfluidic device according to embodiments of the present invention include defining.about.cavity. Polymer precursor solution is positioned in the cavity, and exposed to light to begin the polymerization process and define a microchannel. In some embodiments, after the polymerization process is partially complete, a solvent rinse is performed, or fresh polymer precursor introduced into the microchannel. This may promote removal of unpolymerized material from the microchannel and enable smaller feature sizes. The polymer precursor solution may contain an iniferter. Polymerized features therefore may be capped with the iniferter, which is photoactive. The iniferter may aid later binding of a polyacrylamide gel to the microchannel surface.

  15. Method for forming polymerized microfluidic devices

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, Gregory J. (Livermore, CA); Hatch, Anson V. (Tracy, CA); Wang, Ying-Chih (Pleasanton, CA); Singh, Anup K. (Danville, CA); Renzi, Ronald F. (Tracy, CA); Claudnic, Mark R. (Livermore, CA)

    2011-11-01

    Methods for making a micofluidic device according to embodiments of the present invention include defining a cavity. Polymer precursor solution is positioned in the cavity, and exposed to light to begin the polymerization process and define a microchannel. In some embodiments, after the polymerization process is partially complete, a solvent rinse is performed, or fresh polymer precursor introduced into the microchannel. This may promote removal of unpolymerized material from the microchannel and enable smaller feature sizes. The polymer precursor solution may contain an iniferter. Polymerized features therefore may be capped with the iniferter, which is photoactive. The iniferter may aid later binding of a polyacrylamide gel to the microchannel surface.

  16. Polymeric MST - high precision at low cost

    Science.gov (United States)

    Elderstig, Håkan; Larsson, Olle

    1997-09-01

    A low-cost production process for fabrication of polymeric microstructures from micromachined silicon is demonstrated in a splice for the splicing of optical fibers and an optical motherboard. Measurements on splices showed less than 0.5 dB insertion losses. The prototype polymeric motherboard concisted of an optical receiver module. The detector that was mounted on the polymeric optical motherboard detected about 70% of the transferred light. Measurements with modulated light indicates an optical bandwidth of 5 GHz at 2 V reverse current on the pin-diode.

  17. Polymeric Coatings for Electrodynamic Tethers

    Science.gov (United States)

    Vaughn, Jason A.; Kamenetzky, Rachel R.; Finckenor, Miria M.; Schuler, Peter

    2000-01-01

    Two polymeric coatings have been developed for the Propulsive Small Expendable Deployer System (ProSEDS) mission. ProSEDS is designed to provide an on-orbit demonstration of the electrodynamic propulsion capabilities of tethers in space. The ProSEDS experiment will be a secondary payload on a Delta II unmanned expendable booster scheduled for launch in August 2000. A 5-km conductive tether is attached to the Delta 11 second stage and collects current from the low Earth orbit (LEO) plasma to facilitate de-orbit of the spent stage. The conductive tether is attached to a 10-km non-conductive tether, the other end of which is attached to an endmass containing several scientific instruments. A bare metal tether would have the best conductivity but thermal concerns preclude this design. A conductive polymer developed by Triton Systems has been optimized for conductivity and thermo-optical properties. The current design for the ProSEDS conductive tether is seven strands of 28 AWG aluminum wire individually coated with 8.7 micrometers (0.35 mil) of an atomic oxygen-resistant conductive polymer composed of a mixture of 87% Clear Oxygen-Resistant polymer (COR) and 13% polyanaline (PANi), wrapped around a braided Kevlar (TM) 49 core. Extensive testing has been performed at the Marshall Space Flight Center (MSFC) to qualify this material for flight on ProSEDS. Atomic oxygen exposure was performed, with solar absorptance and infrared emittance measured before and after exposure. Conductivity was measured before and after atomic oxygen exposure. High voltage tests, up to 1500 V, of the current collecting ability of the COR/PANi have been completed. Approximately 160 meters of the conductive tether closest to the Delta 11 second stage is insulated to prevent any electron reconnection to the tether from the plasma contactor. The insulation is composed of polyimide overcoated with TOR-BP, another polymeric coating developed by Triton for this mission. TOR-BP acts as both insulator

  18. Physical Aging of Miscible Polymer Blends

    OpenAIRE

    Robertson, Christopher

    1999-01-01

    Physical aging measurements were performed on various polymeric glasses with the overriding goal of developing a better molecular picture of the nonequilibrium glassy state. To this end, aging-induced changes in mechanical properties and in the thermodynamic state (volume and enthalpy) were assessed for two different miscible polymer blends as a function of both composition and aging temperature. This investigation considered the physical aging behavior of blends containing atactic polystyr...

  19. Polymerization of sodium methacrylate induced by irradiation

    International Nuclear Information System (INIS)

    This work has two objectives, first: it is pretended to localize the lines of carbon links in its IR spectra, and second: following the polymerization of sodium methacrylate according to that it is irradiated with gamma rays. (Author)

  20. Diethynylarenes polymerizations towards conjugated microporous networks

    Czech Academy of Sciences Publication Activity Database

    Balcar, Hynek; Sedláček, J.; Slováková, E.; Zukal, Arnošt; Pastva, Jakub

    Nara: Osaka University, 2013. OC07. [International Symposium on Olefin Metathesis and Related Chemistry /20./. 14.07.2013-19.07.2013, Nara] Institutional support: RVO:61388955 Keywords : polymerization * microporous polymers Subject RIV: CF - Physical ; Theoretical Chemistry

  1. Polymerization as a Model Chain Reaction

    Science.gov (United States)

    Morton, Maurice

    1973-01-01

    Describes the features of the free radical, anionic, and cationic mechanisms of chain addition polymerization. Indicates that the nature of chain reactions can be best taught through the study of macromolecules. (CC)

  2. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Hassager, Ole

    1999-01-01

    We consider the inflation of an axisymmetric polymeric membrane. Some membranes composed of viscoelastic materials described by a Mooney-Rivlin model show a monotone increasingpressure during inflation. These materialsdevelop a homogeneous membrane thickness in agreement with the Considere...

  3. Deformation and flow of polymeric materials

    CERN Document Server

    Münstedt, Helmut

    2014-01-01

    This book describes the properties of single polymer molecules and polymeric materials and the methods how to characterize them. Molar masses, molar mass distributions and branching structure are discussed in detail. These properties are decisive for a deeper understanding of structure/properties relationships of polymeric materials. This book therefore describes and discusses them in detail. The mechanical behavior as a function of time and temperature is a key subject of the book. The authors present it on the basis of many original results they have obtained in their long research careers. They present the temperature dependence of mechanical properties of various polymeric materials in a wide temperature range: from cryogenic temperatures to the melt. Besides an extensive data collection on the transitions of various different polymeric materials, they also carefully present the physical explanations of the observed phenomena. Glass transition and melting temperatures are discussed, particularly, with the...

  4. Silicon dioxide obtained by Polymeric Precursor Method

    International Nuclear Information System (INIS)

    The Polymeric Precursor Method is able for obtaining several oxide material types with high surface area even obtained in particle form. Several MO2 oxide types such as titanium, silicon and zirconium ones can be obtained by this methodology. In this work, the synthesis of silicon oxide was monitored by thermal analysis, XRD and surface area analysis in order to demonstrate the influence of the several synthesis and calcining parameters. Surface area values as higher as 370m2/g and increasing in the micropore volume nm were obtained when the material was synthesized by using ethylene glycol as polymerizing agent. XRD analysis showed that the material is amorphous when calcinated at 600°C in despite of the time of calcining, but the material morphology is strongly influenced by the polymeric resin composition. Using Glycerol as polymerizing agent, the pore size increase and the surface area goes down with the increasing in decomposition time, when compared to ethylene glycol. (author)

  5. Characterization of Polymeric Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Simoncic, B.

    2007-11-01

    Full Text Available As membrane processes are increasingly used in industrial applications, there is a growing interest in methods of membrane characterization. Traditional membrane characteristics, such as cut-off value and pore size distribution, are being supplemented by membrane surface characteristics, such as charge density or zeta potential and hydrophobicity. This study, therefore, characterizes the three different polymeric membranes used (NFT-50, DL and DK. The molecular mass cut-off (MMCO value was determined using a set of reference solutes within the molecular range 150-600 Da, whereas streaming potential measurements enabled quantification of the surface charge characteristics. Hydrophobicity was studied using contact angle measurements. The results indicated that even though all three membranes had very similar layer compositions which consisted of poly(piperazneamide, as top layers they showed different values of measured quantitive. The NFT-50 membrane had the lowest MMCO value and the most hydrophilic membrane surface, followed by DK and DL. Membrane fouling as measured by flux reduction was determined by streaming potential measurements and accompanied by a positive change in zeta potential.

  6. Highly elastic conductive polymeric MEMS

    International Nuclear Information System (INIS)

    Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations. (paper)

  7. Dielectric Coatings for IACT Mirrors

    CERN Document Server

    Förster, A; Chadwick, P; Held, M

    2013-01-01

    Imaging Atmospheric Cherenkov Telescopes for very-high energy gamma-ray astronomy need mirror with high reflectance roughly in the wavelength between 300 and 550 nm. The current standard reflective layer of such mirrors is aluminum. Being permanently exposed to the environment they show a constant degradation over the years. New and improved dielectric coatings have been developed to enhance their resistance to environmental impact and to extend their possible lifetime. In addition, these customized coatings have an increased reflectance of over 95% and are designed to significantly lower the night-sky background contribution. The development of such coatings for mirrors with areas up to 2 m2 and low application temperatures to suite the composite materials used for the new mirror susbtrates of the Cherenkov Telescope Array (CTA) and the results of extensive durability tests are presented.

  8. Virtual gap dielectric wall accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  9. Standards for dielectric elastomer transducers

    Science.gov (United States)

    Carpi, Federico; Anderson, Iain; Bauer, Siegfried; Frediani, Gabriele; Gallone, Giuseppe; Gei, Massimiliano; Graaf, Christian; Jean-Mistral, Claire; Kaal, William; Kofod, Guggi; Kollosche, Matthias; Kornbluh, Roy; Lassen, Benny; Matysek, Marc; Michel, Silvain; Nowak, Stephan; O'Brien, Benjamin; Pei, Qibing; Pelrine, Ron; Rechenbach, Björn; Rosset, Samuel; Shea, Herbert

    2015-10-01

    Dielectric elastomer transducers consist of thin electrically insulating elastomeric membranes coated on both sides with compliant electrodes. They are a promising electromechanically active polymer technology that may be used for actuators, strain sensors, and electrical generators that harvest mechanical energy. The rapid development of this field calls for the first standards, collecting guidelines on how to assess and compare the performance of materials and devices. This paper addresses this need, presenting standardized methods for material characterisation, device testing and performance measurement. These proposed standards are intended to have a general scope and a broad applicability to different material types and device configurations. Nevertheless, they also intentionally exclude some aspects where knowledge and/or consensus in the literature were deemed to be insufficient. This is a sign of a young and vital field, whose research development is expected to benefit from this effort towards standardisation.

  10. Biaxially oriented film on flexible polymeric substrate

    Science.gov (United States)

    Finkikoglu, Alp T.; Matias, Vladimir

    2009-10-13

    A flexible polymer-based template having a biaxially oriented film grown on the surface of a polymeric substrate. The template having the biaxially oriented film can be used for further epitaxial growth of films of interest for applications such as photovoltaic cells, light emitting diodes, and the like. Methods of forming such a flexible template and providing the polymeric substrate with a biaxially oriented film deposited thereon are also described.

  11. Methods of preparing polymeric gradient composites

    OpenAIRE

    A. Dybowska; J. Stabik

    2007-01-01

    Purpose: The goal of this work is to introduce basic methods of preparing polymeric gradient materials, which allow to join two different components to ensure the required properties and structure of the functionally gradient materials.Design/methodology/approach: In this paper few of methods of preparing functionally gradient polymeric materials are briefly described which were successful employed in many investigations performed during last few years.Findings: It was noticed that the knowle...

  12. Polymeric Nanogels Obtained by Radiation Technique

    International Nuclear Information System (INIS)

    Soft nanomaterials - polymeric nanogels and microgels - have made a fast and brilliant career, from an unwanted by-product of polymerization processes to an important and fashionable topic of interdisciplinary research in the fields of polymer chemistry and physics, materials science, pharmacy and medicine. Together with their larger analogues - macroscopic gels, most known in the form of water-swellable hydrogels - they have a broad field of actual and potential applications ranging from filler materials in coating industry to modern biomaterials

  13. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  14. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  15. Nanoscale Polymeric Particles via Aerosol-Photopolymerization

    OpenAIRE

    Akgün, Ertan

    2015-01-01

    This PhD thesis focuses on the process of aerosol-photopolymerization for the generation of various polymeric particles. Such structures are most often prepared by liquid-based methods via the well-established thermal initiation step, and aerosol-photopolymerization is presented as an alternative, aerosol-based technique which employs photoinitiated polymerization. Discussed within this thesis are the advantages and broad aspects of the process.

  16. Extending applications of dielectric elastomer artificial muscle

    Science.gov (United States)

    Chiba, Seiki; Waki, Mikio; Kornbluh, Roy; Pelrine, Ron

    2007-04-01

    Dielectric elastomers have demonstrated high energy density and high strains as well as high electromechanical efficiency and fast speeds of response. These properties, combined with their projected low cost make them attractive for a variety of actuator applications including linear actuators, diaphragm pumps, rotary motors, and haptic displays. Dielectric elastomers have also been shown to offer high energy density, high efficiency, and large strains when operated as generators. Dielectric elastomers have reached a stage of development where standardized products can be applied to new applications. In some cases, dielectric elastomer devices are improvements over existing devices. In other cases, however, dielectric elastomers can enable new types of devices that cannot be made with existing technologies, such as new types of loudspeakers and power generating devices. A new dipole loudspeaker system was developed using a commercially available push-pull diaphragm configuration. This same transducer configuration was used to develop a new power generating system. This generator system enables a power generation of 0.06 to 0.12 W by manually displacing the device by 5 to 6 mm once a second. By introducing a voltage step-down conversion circuit, the device was able to power wireless communications, allowing the control of devices separated by a distance of a few meters. These two devices are examples of the new applications that are enabled as the dielectric elastomer technology commercially emerges. Future improvements to dielectric elastomers could enable new capabilities in clean electrical power generation from ocean waves, for example.

  17. Dielectric investigation of some woven fabrics

    Science.gov (United States)

    Cerovic, Dragana D.; Dojcilovic, Jablan R.; Asanovic, Koviljka A.; Mihajlidi, Tatjana A.

    2009-10-01

    In this paper, we have investigated the temperature dependence of dielectric properties (relative dielectric permeabilities and dielectric tangents of losses) for woven fabrics of hemp, jute, flax, cotton, polyester (PES), cotton-PES mixture, and wool. The measurements have been carried out at a temperature range from -50 to 50 °C in the electric periodic field at a frequency 1 MHz in vacuum. For the same specimens, the values of the dielectric properties have also been measured at an air temperature of 21 °C and at relative humidities of 40%, 60%, and 80%. At different frequencies from 80 kHz to 5 MHz, the dielectric properties have been measured at a relative humidity of 40% and at a temperature of 21 °C. An investigation of the dielectric properties of woven fabrics can provide a better understanding of the relation between the dielectric properties of woven fabrics and the different raw material compositions, temperatures, relative air humidities, and frequencies for specimens. Hence, this investigation helps to improve textile material properties.

  18. Autonomous dielectric elastomer generator using electret

    Science.gov (United States)

    Vu-Cong, T.; Jean-Mistral, C.; Sylvestre, A.

    2013-04-01

    Dielectric elastomers can work as a variable capacitor to convert mechanical energy such as human motion into electrical energy. Nevertheless, scavengers based on dielectric elastomers require a high voltage source to polarize them, which constitutes the major disadvantage of these transducers. We propose here to combine dielectric elastomer with an electret, providing a quasi-permanent potential, thus replacing the high voltage supply. Our new scavenger is fully autonomous, soft, lightweight and low cost. Our structure is made of a dielectric elastomer (Polypower from Danfoss) and an electret developing a potential of -1000V (Teflon from Dupont). The transducer is designed specifically to scavenge energy from human motion. Thus, it works on pure-shear mode with maximum strain of about 50% and it is textured in 3D form because electret is not deformable. The shape of the hybrid structure is critical to insure huge capacitance variation and thus higher scavenged energy. We present in this paper our process for the optimization of the 3D shape that leads us to the developpment and characterization of our first prototype. From an appropriate electromechanical analytical model, an energy density of about 1.48mJ.g-1 is expected on an optimal electrical load. Our new autonomous dielectric generator can produce about 0.55mJ.g-1 on a resistive load, and can further be improved by enhancing the performance of dielectric elastomer such as dielectric permittivity or by increasing the electret potential.

  19. Dielectric resonances in disordered media

    Science.gov (United States)

    Raymond, L.; Laugier, J.-M.; Schäfer, S.; Albinet, G.

    2003-02-01

    Binary disordered systems are usually obtained by mixing two ingredients in variable proportions: conductor and insulator, or conductor and super-conductor. They present very specific properties, in particular the second-order percolation phase transition, with its fractal geometry and the multi-fractal properties of the current moments. These systems are naturally modeled by regular bi-dimensional or tri-dimensional lattices, on which sites or bonds are chosen randomly with given probabilities. The two significant parameters are the ratio h = σ1/σ of the complex conductances, σ and σ1, of the two components, and their relative abundances p (or, respectively, 1 - p). In this article, we calculate the impedance of the composite by two independent methods: the so-called spectral method, which diagonalises Kirchhoff's Laws via a Green function formalism, and the Exact Numerical Renormalization method (ENR). These methods are applied to mixtures of resistors and capacitors (R-C systems), simulating e.g. ionic conductor-insulator systems, and to composites constituted of resistive inductances and capacitors (LR-C systems), representing metal inclusions in a dielectric bulk. The frequency dependent impedances of the latter composites present very intricate structures in the vicinity of the percolation threshold. In this paper, we analyse the LR-C behavior of compounds formed by the inclusion of small conducting clusters (``n-legged animals'') in a dielectric medium. We investigate in particular their absorption spectra who present a pattern of sharp lines at very specific frequencies of the incident electromagnetic field, the goal being to identify the signature of each animal. This enables us to make suggestions of how to build compounds with specific absorption or transmission properties in a given frequency domain.

  20. The tempered polymerization of human neuroserpin.

    Directory of Open Access Journals (Sweden)

    Rosina Noto

    Full Text Available Neuroserpin, a member of the serpin protein superfamily, is an inhibitor of proteolytic activity that is involved in pathologies such as ischemia, Alzheimer's disease, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB. The latter belongs to a class of conformational diseases, known as serpinopathies, which are related to the aberrant polymerization of serpin mutants. Neuroserpin is known to polymerize, even in its wild type form, under thermal stress. Here, we study the mechanism of neuroserpin polymerization over a wide range of temperatures by different techniques. Our experiments show how the onset of polymerization is dependent on the formation of an intermediate monomeric conformer, which then associates with a native monomer to yield a dimeric species. After the formation of small polymers, the aggregation proceeds via monomer addition as well as polymer-polymer association. No further secondary mechanism takes place up to very high temperatures, thus resulting in the formation of neuroserpin linear polymeric chains. Most interesting, the overall aggregation is tuned by the co-occurrence of monomer inactivation (i.e. the formation of latent neuroserpin and by a mechanism of fragmentation. The polymerization kinetics exhibit a unique modulation of the average mass and size of polymers, which might suggest synchronization among the different processes involved. Thus, fragmentation would control and temper the aggregation process, instead of enhancing it, as typically observed (e.g. for amyloid fibrillation.

  1. Dielectric barrier discharge treatments for heparin immobilization on PVC films

    International Nuclear Information System (INIS)

    Low temperature plasmas represent a useful technique to modify the mechanical and physico-chemical characteristics of polymer surfaces. Among these techniques, the dielectric barrier discharge (DBD) can be used to initiate the functionalization, crosslinking, and/or chemical incorporation of various functional groups on these surfaces. In particular, this technique may be used to immobilize some biological active species interested in medical applications, for example the heparin. Thrombus formation on the implant is one of major processes at the blood/biomaterial interface and one of the solution to control the mechanism of the blood coagulation is to incorporate an anticoagulant element within the surface boundary layers of the implant. Heparin is an anticoagulant that can enhance the inactivation of clotting factors and, theoretically, it can be immobilized by ionic or covalent linkages on the polymeric surface. In this way, the hemocompatibility of the polymeric surfaces could increase, permitting to construct devices such as cardiopulmonary bypass circuits, hemodialyses, ventricular devices, etc., for what the thrombus formation and leukocyte activation is critical. Among the most common polymers used in medical applications, polyvinyl chloride (PVC) films are preferred, satisfying a wide range of safety performances and cost criteria. They are used to store substances e. g., blood and blood products drugs and injectables, membranes for gas adsorption etc. The physico-chemical and biological properties of PVC depend on the nature of the biological environment and of the amount of additives. In contact with the biological liquids and the blood, some elements from these are capable of extracting additives from PVC films and in very short time, the patient exposed to the implant might receive doses of plasticizers (for example) with the risk of possible toxic and biological effects due the transfer of these additives to the tissues. At the same time, depending on

  2. Dielectric behaviour of strontium tartrate single crystals

    Indian Academy of Sciences (India)

    S K Arora; Vipul Patel; Brijesh Amin; Anjana Kothari

    2004-04-01

    Strontium tartrate trihydrate (STT) crystals have been grown in silica hydrogel. Various polarization mechanisms such as atomic polarization of lattice, orientational polarization of dipoles and space charge polarization in the grown crystals have been understood using results of the measurements of dielectric constant (') and dielectric loss (tan ) as functions of frequency and temperature. Ion core type polarization is seen in the temperature range 75–180°C, and above 180°C, there is interfacial polarization for relatively lower frequency range. One observes dielectric dispersion at lower frequency presumably due to domain wall relaxation.

  3. Development of dielectric-barrier-discharge ionization.

    Science.gov (United States)

    Guo, Cheng'an; Tang, Fei; Chen, Jin; Wang, Xiaohao; Zhang, Sichun; Zhang, Xinrong

    2015-03-01

    Dielectric-barrier-discharge ionization is an ambient-ionization technique. Since its first description in 2007, it has attracted much attention in such fields as biological analysis, food safety, mass-spectrometry imaging, forensic identification, and reaction monitoring for its advantages, e.g., low energy consumption, solvent-free method, and easy miniaturization. In this review a brief introduction to dielectric barrier discharge is provided, and then a detailed introduction to the dielectric-barrier-discharge-ionization technique is given, including instrumentation, applications, and mechanistic studies. Based on the summary of reported work, possible future uses of this type of ionization source are discussed at the end. PMID:25510973

  4. Microwave dielectric properties of nanostructured nickel ferrite

    Indian Academy of Sciences (India)

    John Jacob; M Abdul Khadar; Anil Lonappan; K T Mathew

    2008-11-01

    Nickel ferrite is one of the important ferrites used in microwave devices. In the present work, we have synthesized nanoparticles of nickel ferrite using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The microwave dielectric properties of nanostructured nickel ferrite samples of three different average grain sizes and those of two sintered samples were studied. The parameters like dielectric constant, dielectric loss and heating coefficient of the nanoparticles samples are studied in the frequency range from 2.4 to 4 GHz. The values of these parameters are compared with those of sintered pellets of the same samples. All these parameters show size dependent variations.

  5. Characterization behavior of some polymeric composite ion exchangers

    International Nuclear Information System (INIS)

    Polymeric composite resins were prepared by template polymerization process in aqueous solution. Thermogravimetric analysis (TGA), differential thermal analysis (DTA) and The X-ray diffraction patterns (XRD) were performed to evaluate the physico chemical properties of the different polymeric composite resins. The TGA and DTA clarify high thermal stability of prepared polymeric composite resins. XRD of prepared polymeric composite shows that there is crystalline structure of some resins while other are amorphous one

  6. Fluoropolymer materials and architectures prepared by controlled radical polymerizations

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Jankova Atanasova, Katja; Hvilsted, Søren

    2007-01-01

    This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition–fragmentation chain...... transfer (RAFT) polymerization. This is followed by two parts, one dealing with homo- and copolymerizations of fluorinated methacrylates and acrylates, and a second where fluorinated styrenes, alone or in combination with other monomers, are the main issues. In these parts, initiators (including...

  7. Optical, dielectric and electrical properties of PVA doped with Sn nanoparticles

    International Nuclear Information System (INIS)

    Films of pure and doped polyvinyl alcohol (PVA) with different concentrations of Sn nanoparticles (not ≦ 100 nm) were prepared using casting technique. The effect of Sn addition on micro-structural, optical, electrical and dielectric properties of PVA was investigated. Microstructure of Sn/PVA nanocomposite films was characterized by scanning electron microscopy (SEM). Dielectric properties and ac conductivity measurements were carried out at room temperature over a wide range of frequencies ranging from 50 Hz to 5 MHz. AC conductivity was found to increase with frequency. Besides, addition of Sn nanoparticles to PVA leads to a change in conductivities of the films. Coulomb blockade effect was found to dominate at certain concentrations of Sn which may be used to explain the obtained results. The dielectric properties of the Sn/PVA films were also investigated and results were discussed in correlation with the relevant models. The frequency dependence of the imaginary part of complex electric modulus for the Sn/PVA composites shows a loss peak attributed to interfacial polarization at a certain frequency. Optical energy gap of Sn/PVA films was determined and found to decrease for Sn concentrations up to 20% due to the interaction between the Sn nanoparticles and the host polymeric network leading to the creation of new molecular dipoles. For higher Sn concentrations, the optical energy gap starts to increase which may be resulting from structural changes leading to passivation of localized states near the band edges and hence widening of the energy gap. (papers)

  8. Sulfone-Containing Dipolar Glass Polymers with High Dielectric Constant and Low Loss Property

    Science.gov (United States)

    Zhu, Yufeng; Zhang, Zhongbo; Litt, Morton; Zhu, Lei

    Sulfone-containing polyoxetanes are designed and synthesized for high dielectric constant and low loss dipolar glasses. The precursor polymer, poly(3,3-bis(chloromethyl)oxetane) (PBCMO) is synthesized by bulk cationic polymerization with boron trifluoride diethyl etherate as initiator. The number-average molecular weight of PBCMO is 73 kDa, with a polydispersity of 1.53 as obtained from size-exclusion chromatography results. Post-modification of PBCMO yields the dipolar glass polymer, poly(3,3-bis(methylsulfonylmethyl)oxetane) (MST). Nuclear magnetic resonance result shows 100% conversion. Differential scanning calorimetry result indicates that MST has a glass transition temperature of ca. 120 °C. Due to the large dipole moment (4.25 D) and small size of the side-chain sulfone groups, MST exhibits a high dielectric constant of 8.7 and a low dissipation factor of 0.01 at 25 °C and 1 Hz. This study suggests that dipolar glass polymers with large dipole moments and small-sized dipoles in the side chains are promising candidates for high energy density and low loss dielectric applications. This work is supported by NSF Polymers Program (DMR-1402733).

  9. Dielectric/Ag/dielectric coated energy-efficient glass windows for warm climates

    Energy Technology Data Exchange (ETDEWEB)

    Durrani, S.M.A.; Khawaja, E.E. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Center for Applied Physical Sciences; Al Shukri, A.M.; Al Kuhaili, M.F. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Physics

    2004-09-01

    Energy-efficient glass windows for warm climates were designed and fabricated using a three-layer system of dielectric/metal/dielectric (D/M/D) on glass. Silver was used as a metal layer. The design parameters for optimum performance of D/M/D on glass-systems for dielectrics, having refractive indices in the range 1.6-2.4, were obtained by numerical calculations. Based on these parameters, D/M/D films on glass substrates were deposited using dielectrics such as TiO{sub 2}, WO{sub 3}, and ZnS. Upon testing these coated glass windows, it was concluded that the window with any of the three dielectrics performed well and the efficiencies of the windows with different dielectrics were nearly the same. [Author].

  10. Photothermal dielectric spectroscopy: A novel technique for the determination of the dielectric, pyroelectric and thermal properties of thin dielectric films

    OpenAIRE

    Wübbenhorst, Michael; van Turnhout, Jan

    1994-01-01

    A novel technique is described which combines dielectric measurements with a time and frequency dependent photothermal excitation. The sample, a thin metallized film, is placed in an aluminium ring which serves as a heat sink. At different temperatures both the dielectric and pyroelectric spectra are obtained by applying sequentially an AC-voltage and a modulated heat flux to the sample. The thermal properties are assessed by the application of a local laser heating; the resulting increase in...

  11. Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

    OpenAIRE

    Medeiros Jamilson Pinto; Tavares Elcio Correia de Souza; Gomes Uilame Umbelino; Acchar Wilson

    1998-01-01

    Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-...

  12. Dielectric relaxation in dielectric mixtures: Application of the finite element method and its comparison with dielectric mixture formulas

    International Nuclear Information System (INIS)

    In this article, the frequency dependent dielectric properties, var-epsilon(ω), of an 'ideal binary composite structure were investigated by using the finite element method in the frequency domain. The material properties of the phases, i.e., dielectric permittivity, ε, and direct-current conductivity, σ, were assumed to be frequency independent. Moreover, the inclusion phase was more conductive than the matrix phase. The inclusions were infinitely long unidirectional cylinders which could be assumed to be hard disks in two dimensions in the direction perpendicular to the cylinder direction. Three different inclusion concentration levels were considered, e.g., low, intermediate, and high. The calculated dielectric relaxations were compared with those of the dielectric mixture formulas in the literature and it was found that there were no significant differences between the formulas and the numerical solutions at low inclusion concentration. Furthermore, the obtained responses were curve fitted by the addition of the Cole - Cole empirical expression and the ohmic losses by using a complex nonlinear least squares algorithm in order to explain the plausible physical origin of the Cole - Cole type dielectric relaxation. The dielectric relaxations were Debye-like when the concentration of the inclusions were low. For intermediate and high concentrations, the responses obtained from the numerical simulations deviated from that of the Debye one, whose curve fittings with the Cole - Cole empirical expression were inadequate. [copyright] 2001 American Institute of Physics

  13. Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

    OpenAIRE

    Hidetaka Tobita

    2016-01-01

    When the size of a polymerization locus is smaller than a few hundred nanometers, such as in miniemulsion polymerization, each locus may contain no more than one key-component molecule, and the concentration may become much larger than the corresponding bulk polymerization, leading to a significantly different rate of polymerization. By focusing attention on the component having the lowest concentration within the species involved in the polymerization rate expression, a simple formula can pr...

  14. Effects of heavy metal on dielectric properties of E.coli revealed by dielectric spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Bai Wei; Zhao Kongshuang

    2006-01-01

    Dielectric spectroscopy of E.coli cell before and after exposure to heavy metals Cd2+,Cu2+, Zn2+ and Ca2+ was investigated. The results indicate that changes in dielectric spectra reflect effects of heavy metal on the structure and function of E.coli cells. Heavy metal can change membrane capacitance as well as permittivity and conductivity of the cytoplasm. Changes in volume fraction suggested that dielectric measurement could monitor the growth of E.coli cells. These results demonstrated that dielectric spectroscopy was a potential effective technique for studying electric properties of biological cells.

  15. Identification of Structural Relaxation in the Dielectric Response of Water

    Science.gov (United States)

    Hansen, Jesper S.; Kisliuk, Alexander; Sokolov, Alexei P.; Gainaru, Catalin

    2016-06-01

    One century ago pioneering dielectric results obtained for water and n -alcohols triggered the advent of molecular rotation diffusion theory considered by Debye to describe the primary dielectric absorption in these liquids. Comparing dielectric, viscoelastic, and light scattering results, we unambiguously demonstrate that the structural relaxation appears only as a high-frequency shoulder in the dielectric spectra of water. In contrast, the main dielectric peak is related to a supramolecular structure, analogous to the Debye-like peak observed in monoalcohols.

  16. All-dielectric subwavelength metasurface focusing lens.

    Science.gov (United States)

    West, Paul R; Stewart, James L; Kildishev, Alexander V; Shalaev, Vladimir M; Shkunov, Vladimir V; Strohkendl, Friedrich; Zakharenkov, Yuri A; Dodds, Robert K; Byren, Robert

    2014-10-20

    We have proposed, designed, manufactured and tested low loss dielectric micro-lenses for infrared (IR) radiation based on a dielectric metamaterial layer. This metamaterial layer was created by patterning a dielectric surface and etching to sub-micron depths. For a proof-of-concept lens demonstration, we have chosen a fine patterned array of nano-pillars with variable diameters. Gradient index (GRIN) properties were achieved by engineering the nano-pattern characteristics across the lens, so that the effective optical density of the dielectric metamaterial layer peaks around the lens center, and gradually drops at the lens periphery. A set of lens designs with reduced reflection and tailorable phase gradients have been developed and tested, demonstrating focal distances of a few hundred microns, beam area contraction ratio up to three, and insertion losses as low as 11%. PMID:25401653

  17. Casimir Torque in Inhomogeneous Dielectric Plates

    CERN Document Server

    Long, William

    2013-01-01

    In this work, we consider a torque caused by the well known quantum mechanical Casimir effect arising from quantized field fluctuations between plates with inhomogeneous, sharply discontinuous, dielectric properties. While the Casimir effect is a relatively well understood phenomenon, systems resulting in lateral or rotational forces are far less developed; to our knowledge, a theoretical study of discontinuous dielectric variants of such systems has not been attempted. We utilize a Proximity Force Approximation in conjunction with the Lifshitz dielectric formula to perform theoretical analyses of resultant torques in systems with bisected and quadrisected dielectric regions. We also develop a high precision Monte Carlo type numerical integrator to approximate our derived expressions. Our calculations of an energy density linear with the alignment angle result in a constant torque and have implications in NEMS (nano electromechanical systems) and MEMS (micro electromechanical systems), including a postulated ...

  18. High Gradient Wakefields in Dielectric Loaded Structures

    International Nuclear Information System (INIS)

    Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches

  19. Multipactor experiment on a dielectric surface

    International Nuclear Information System (INIS)

    A novel experiment to investigate single-surface multipactor on a dielectric surface was developed and tested. The compact apparatus consists of a small brass microwave cavity in a high vacuum system. The cavity is ∼15 cm in length with an outer diameter of ∼10 cm. A pulsed variable frequency microwave source at ∼2.4 GHz, 2 kW peak excites the TE111 mode with a strong electric field parallel to a dielectric plate (∼0.2 cm thickness) that is inserted at midlength of the cavity. The microwave pulses are monitored by calibrated microwave diodes. An electron probe measures electron current and provides temporal measurements of the multipactor electron current with respect to the microwave pulses. Phosphor on the dielectric surface is used to detect multipactor electrons by photoemission. The motivation of this experiment is to test recent theoretical calculations of single-surface multipactor on a dielectric

  20. A study of microcalorimeter with dielectric thermometer

    International Nuclear Information System (INIS)

    The microcalorimeter detects a single particle of radiation by means of the temperature rise in the absorber kept at low temperature below 1 K. A sensitive thermometer measuring the temperature rise is an important component in the microcalorimeter. Dielectric materials whose electric capacitances depend on temperature at low temperature can be utilized for the sensitive thermometer of the microcalorimeter. The temperature dependence of the electric capacitance d(ln Cd)/dT is an important parameter for the dielectric thermometer. We have studied the dielectric thermometer made of SrTiO3 based material and carried out measurement of the electric capacitance in the temperature range from 50 mK to 120 mK. By using experimental values of d(ln Cd)/dT an output signal of the dielectric microcalorimeter was estimated in the detection of a 5.5 MeV α-particle. (author)

  1. Survey and research on precision polymerization polymeric materials; Seimitsu jugo kobunshi zairyo ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    Survey and research on the precision control of primary structure of polymeric materials and the precision evaluation technology have been conducted to develop advanced polymeric materials. It is proposed that the three basic processes of polymer synthesis, i.e., addition, condensation, and biomimesis, in forming the precision polymerization skeleton are to be covered through a centralized joint research effort with participation of industry, academia, and the government institute and under the leadership of researchers from academic institutions as the team leaders. For the study of technology trends, international conferences held in UK, Germany, and Hawaii are introduced, and domestic meetings, i.e., Annual Polymer Congress and Polymer Conference, are summarized. In addition, Precision Polymerization Forum and International Workshop on Precision Polymerization were held. The basic studies include a quantum-chemical elucidation of the elementary process in polymerization reaction, time-resolved analysis of polymerization process and polymer properties, synthesis of polymers with controlled microstructures by coordination polymerization using metal complexes, synthesis of polymer with controlled microstructures by precision polycondensation, molecular recognition in catalyst-reaction site, and synthesis of imprinting polymers. 246 refs., 117 figs., 14 tabs.

  2. Polariton spectrum in nonlinear dielectric medium

    OpenAIRE

    Dzedolik, Igor V.; Karakchieva, O.

    2012-01-01

    We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third order dielectric susceptibility at intensity field in the medium. The modulation instability of new branch...

  3. Polariton waves in nonlinear dielectric medium

    OpenAIRE

    Dzedolik, I. V.; Karakchieva, O. S.

    2012-01-01

    The phonon-polariton spectrum in dielectric medium with the third order nonlinearity was theoretically obtained. Dependence of number of polariton spectrum branches on intensity of electromagnetic field was investigated. The appearance of new branches located in the polariton spectrum gap was caused by the influence of dispersion of the third order dielectric susceptibility at increment of the field intensity in the medium. The soliton and cnoidal wave solutions for the polariton excitations ...

  4. PREFACE: Dielectrics 2009: Measurement Analysis and Applications

    Science.gov (United States)

    Vaughan, Alun; Williams, Graham

    2009-07-01

    The conference Dielectrics 2009: Measurements, Analysis and Applications represents a significant milestone in the evolution of dielectrics research in the UK. It is reasonable to state that the academic study of dielectrics has led to many fundamental advances and that dielectric materials underpin the modern world in devices ranging from field effect transistors, which operate at extremely high fields, albeit low voltages, to the high voltage plants that provide the energy that powers our economy. The origins of the Dielectrics Group of the Institute of Physics (IOP), which organized this conference, can be traced directly back to the early 1960s, when Professor Mansel Davies was conducting research into the dielectric relaxation behaviour of polar liquids and solids at The Edward Davies Chemical Laboratories of the University College of Wales, Aberystwyth. He was already well-known internationally for his studies of molecular structure and bonding of small molecules, using infra-red-spectroscopy, and of the physical properties of hydrogen-bonded liquids and solids, using thermodynamic methods. Dielectric spectroscopy was a fairly new area for him and he realized that opportunities for scientists in the UK to gather together and discuss their research in this developing area of physical chemistry/chemical physics were very limited. He conceived the idea of forming a Dielectrics Discussion Group (DDG), which would act as a meeting point and provide a platform for dielectrics research in the UK and beyond and, as a result, a two-day Meeting was convened in the spring of 1968 at Gregynog Hall of the University of Wales, near Newtown, Montgomeryshire. It was organized by Mansel Davies, Alun Price and Graham Williams, all physical chemists from the UCW, Aberystwyth. Fifty scientists attended, being a mix of physical chemists, theoretical chemists, physicists, electrical engineers, polymer and materials scientists, all from the UK, except Dr Brendan Scaife of Trinity

  5. Dielectric properties of Jordanian oil shales

    Energy Technology Data Exchange (ETDEWEB)

    Al-Harahsheh, Mohammad; Alnawafleh, Hani [Department of Mining Engineering, College of Mining and Environmental Engineering, Al-Hussein Bin Talal University, Ma' an 20 (Jordan); Kingman, Sam; Saeid, Abdurrahman; Robinson, John; Dimitrakis, Georgios [Process and Environmental Research Division Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD (United Kingdom)

    2009-10-15

    Microwave heating has been suggested by various authors as a suitable technology for extraction of organic material from oil shales. However, one of the limiting factors in the development of this technology is a lack of accurate dielectric property data for design purposes. In this study the dielectric behaviour of El-lajun oil shale is quantified. The dielectric constant and loss factor of El-lajun oil shale were measured at 2470 and 912 MHz using the cavity perturbation technique. The effects of organic content, temperature, and moisture content on the microwave heating efficiency were quantified. Coaxial probe technique was also employed to study the effect of frequency on dielectric properties of oil shale. Generally, it was found that all samples were of low dielectric loss at room temperature with the imaginary part of permittivity falling significantly after the moisture was removed. This suggests that the major contribution in the dielectric loss is due to the presence of free and/or interlayer water. It was found that both the real and imaginary part of complex permittivity increased with a rise in temperature from 20 up to 80 C, then dropped significantly at about 100 C before staying approximately constant up to a temperature of about 480 C. From this temperature both the real and imaginary parts of complex permittivity increased sharply with further increase in temperature. An attempt was also made to correlate the dielectric properties of the bulk shale sample with the organic content. However, no correlation between dielectric properties and organic matter content was found. (author)

  6. Dielectric Behavior of Middle Phase Microemulsion

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Dielectric measurements were performed on middle phase microemulsions composed of sodium dodecylsulfate(SDS), cetyltrimethylammonium bromide(CTAB), n-butanol, n-heptane and brine. Distinct and unique dielectric behavior, with characteristic frequency dependence regularity on the salinity of the microemulsions, was observed in the low-frequency range from 10-103Hz. It can be considered to be an interfacial polarization mechanism.

  7. Formation of microporous polymeric materials by microemulsion radiation polymerization of butyl acrylate

    International Nuclear Information System (INIS)

    A microemulsion system composed of butyl acrylate (BA) and water with the mixture of sodium 12-acryloxy-9-octadecenate (SAO) and octylphenoxypoly(ethoxyethanol) (OP-10) as emulsifier was initiated by γ-ray at room temperature to polymerize and produce microporous polymeric materials. The morphology and swelling characteristics of the resulting polymeric materials were studied. It was found that they depend strongly on the composition (water content, crosslinker content, emulsifier content) of the precursor microemulsions. In addition, the swelling properties of polymer so prepared were also found to be sensitive to the pH of the swelling medium. The change in swelling behaviors of the polymeric materials is discussed in terms of the polyelectrolyte effect exhibited by polymerized anionic emulsifier SAO. (author)

  8. Dielectric silicone elastomers with mixed ceramic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Stiubianu, George, E-mail: george.stiubianu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Ignat, Mircea [National R& D Institute for Electrical Engineering ICPE-CA Bucharest, Splaiul Unirii 313, District 3, Bucharest 030138 (Romania)

    2015-11-15

    Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

  9. Dielectric modelling of erythrocyte aggregation in blood

    International Nuclear Information System (INIS)

    The dielectric spectrum of whole blood is markedly changed by aggregation of erythrocytes, the so-called rouleau formation. The dielectric behaviour has been simulated using an erythrocyte model that is a disc covered with a thin membrane and an erythrocyte aggregate model that is a pile of the discs with regular spacing ds. The effective complex permittivity of a cubic system including one of the models was calculated by a numerical technique based on the three-dimensional finite-difference method. Both the models have anisotropic dielectric properties depending on whether the rotational axis of the separate or the aggregate model is parallel (the parallel orientation) or perpendicular (the perpendicular orientation) to the direction of the applied electric field. The models both showed a single dielectric relaxation, which was different in intensity and characteristic frequency between the two orientations. For the erythrocyte aggregate model, the relaxation intensity Δε increased and the characteristic frequency fc decreased with decreasing ds in the perpendicular orientation, whereas the opposite ds-dependence was found for Δε and fc in the parallel orientation. Increasing the number of cells in the aggregate model enhanced these effects. The difference in dielectric spectrum between the separate and the aggregate models represented well the dielectric spectrum change caused by rouleau formation

  10. Printable ion-gel gate dielectrics for low-voltage polymer thin-film transistors on plastic.

    Science.gov (United States)

    Cho, Jeong Ho; Lee, Jiyoul; Xia, Yu; Kim, BongSoo; He, Yiyong; Renn, Michael J; Lodge, Timothy P; Frisbie, C Daniel

    2008-11-01

    An important strategy for realizing flexible electronics is to use solution-processable materials that can be directly printed and integrated into high-performance electronic components on plastic. Although examples of functional inks based on metallic, semiconducting and insulating materials have been developed, enhanced printability and performance is still a challenge. Printable high-capacitance dielectrics that serve as gate insulators in organic thin-film transistors are a particular priority. Solid polymer electrolytes (a salt dissolved in a polymer matrix) have been investigated for this purpose, but they suffer from slow polarization response, limiting transistor speed to less than 100 Hz. Here, we demonstrate that an emerging class of polymer electrolytes known as ion gels can serve as printable, high-capacitance gate insulators in organic thin-film transistors. The specific capacitance exceeds that of conventional ceramic or polymeric gate dielectrics, enabling transistor operation at low voltages with kilohertz switching frequencies. PMID:18931674

  11. The influence of temperature on the polymerization of ethyl cyanoacrylate from the vapor phase

    Energy Technology Data Exchange (ETDEWEB)

    Dadmun, Mark D [ORNL; Algaier, Dana [University of Tennessee, Knoxville (UTK); Baskaran, Durairaj [University of Tennessee, Knoxville (UTK)

    2011-01-01

    The polymerization of ethyl cyanoacrylate fumes from surface bound initiators is an important step in many novel and mature technologies. Understanding the effect of temperature on the rate of poly(ethyl cyanoacrylate) (PECA) growth and its molecular weight during its polymerization from the vapor phase from surface bound initiators provides insight into the important mechanistic aspects that impact the polymerizations success. In these studies, it is shown that the amount of PECA formed during the polymerization of ECA from a latent fingerprint increases with decreasing temperature, while the polymer molecular weight varies little. This is interpreted to be the result of the loosening of the ion pair that initiates the polymer chain growth and resides on the end of the growing polymer chain with decreasing temperature. Comparison of temperature effects and counter-ion studies show that in both cases loosening the ion pair results in the formation of more polymer with similar molecular weight, verifying this interpretation. These results further suggest that lowering the temperature may be an effective method to optimize anionic vapor phase polymerizations, including the improvement of the quality of aged latent prints and preliminary results are presented that substantiate this prediction.

  12. Deposition of a thin electro-polymerized organic film on iron surface

    International Nuclear Information System (INIS)

    We use an electrochemical method to prepare a polymerized thin film, obtained from acrylonitrile in a solution of acetonitrile and tetraethylammonium perchlorate. The films are deposited on oxidized iron electrodes, with a surface area varying from a few mm to several cm, their thickness ranges from ten A to thousand A. This result is obtained by controlling the evolution of reactions: duplication, hydrogenation, polymerization which occur during the electrochemical reduction of acrylonitrile. The choice of suitable experimental conditions enhances the polymerization and increases the adherence of the polymer on the electrode. The usual methods of surface studies: S.E.M., A.E.S., S.I.M.S., permit the characterization of the electrode surface and the chemical composition of the deposit films. The molecular structure of polymer, and its evolution under aging or heating was studied by infrared multi-reflection spectroscopy. Very good correlation exists between the electrochemical characteristic: I = f(t), the initial surface state of the electrodes, and the homogeneity of the electro-polymerized films. Diagrams corresponding to mechanisms of different stages of electro-polymerization are proposed. (author)

  13. Fire-Retardant Polymeric Additives

    Science.gov (United States)

    Williams, Martha K.; Smith, Trent M.

    2011-01-01

    component forms polybenzoxazole (PBO) in a reaction that absorbs heat from its surroundings. PBO under thermal stress cross-links, forming a protective char layer, which thermally insulates the polymer. Thus, the formation of the char layer further assists to extinguish the fire by preventing vaporization of the polymeric fuel.

  14. Growth and characterization of MMA/SiO2 hybrid low- thin films for interlayer dielectric applications

    Indian Academy of Sciences (India)

    Bhavana N Joshi; M A More; A M Mahajan

    2010-06-01

    The methylmethacrylate (MMA) incorporated SiO2 thin films having low dielectric constant ( = 2.97) were deposited successfully to realize new interlayer material for the enhancement of electrical performance of on-chip wiring in very large scale integrated (VLSI) circuits. We have successfully incorporated MMA monomer and eliminated the polymerization step to lower the dielectric constant of deposited thin film. The presence of peak of C=C bond in Fourier transform infrared (FTIR) spectra and carbon peak in energy dispersive (EDAX) spectra confirms the incorporation of carbon in the film due to MMA. The concentration of MMA has great impact on the peak area and full width at half maxima (FWHM) of the Si–O–Si bond, which decreases the density by low atomic weight elements and consequently decreases the dielectric constant. The surface morphology analysed by scanning electron microscopic (SEM) image shows excellent uniformity of the film. The refractive index of 1.31 was measured by ellipsometer for 0.5 ml MMA concentration film. These deposited thin films having low refractive index and dielectric constant are widely applicable for the optical interconnects and interlayer applications in integrated optical circuits and VLSI circuits.

  15. Catalytic Polymerization of Acrylonitrile by Khulays Bentonite

    Directory of Open Access Journals (Sweden)

    Matar M. Al-Esaimi

    2007-04-01

    Full Text Available The aqueous polymerization of acrylonitrile (AN catalyzed with exchanged Khulays bentonite . The influence of various polymerization parameters ( e.g., concentrations of Potassium Persulfate (K2S2O8 and monomer , various of organic solvents, and different temperature has been investigated. It was found that the rate of polymerization of AN was found to be dependent on monomer concentration, initiator and temperature. The activation energy of polymerization was calculated .Thermal properties of the polymer were studied by TGA and DSC techniques. © 2007 CREC UNDIP. All rights reserved.Received: 5 February 2007; Received in revised: 19 April 2007; Accepted: 7 May 2007[How to Cite: M. M. Al-Esaimi. (2007. Catalytic Polymerization of Acrylonitrile by Khulays Bentonite. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 32-36.  doi:10.9767/bcrec.2.1.4.6-10][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.1.4.6-10 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/4] 

  16. Applications or radiation polymerization hardening to composites

    International Nuclear Information System (INIS)

    Comprehensive investigation has been made into the application of the polymerization hardening by radiation, particularly electron beam, to the composites of polymers and other materials. The report is divided into four parts, namely 1) characteristics and problems of the reaction of curing by radiation polymerization, 2) improvement of the bonding capability of high molecular weight materials, 3) bonding by radiation, and 4) composites made by the impregnation and polymerization hardening of monomers. The first part includes the effects of dose rate, temperature rise during the hardening, the peculiarity of electron beam irradiation at high dose rate, reaction environment and additive effects. Main conclusions are as follows: caution must be taken to the amount of residual double bonds because they affect the quality of hardened polymers; the polymerization hardening reaction at high dose rate cannot be analogized by that at low dose rate; and the presence of the inhibitors of radical reaction is not preferable. The second part includes the surface treatment by irradiation and radiation graft polymerization. The irradiation of electron beam and chromic acid treatment are the most effective processes for the surface treatment, but some caution is required. The third part includes hair plantation and laminated films. The uses of adhesive tapes and vinyl wall papers are anticipated. The fourth part includes fiber reinforced plastics (FRP), concrete-polymer composites (CPC) and wood-plastic composites (WPC). (Iwakiri, K.)

  17. Dielectric and Ferroelectric Properties of Complex Perovskite Ceramics Under Compressive Stress

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Dielectric and ferroelectric properties of complex perovskite PZT-PZN ceramic system were investigated under the influence of the compressive stress. The results showed that the dielectric properties, i.e. dielectric constant ( εr ) and dielectric loss ( tan δ), and the ferroelectric characteristics, i.e. the area of the ferroelectric hysteresis loops, the saturation polarization ( P(sat) ), and the remnant polarization (Pr) changed significantly with increasing compressive stress. These changes depended strongly on the ceramic compositions. The experimental results on the dielectric properties could be explained by both intrinsic and extrinsic domain-related mechanisms involving domain wall motions, as well as the de-aging phenomenon. The stress-induced domain wall motion suppression and non-180° ferroelectric domain switching processes were responsible for the changes observed in the ferroelectric parameters. In addition,a significant decrease in those parameters after a cycle of stress was observed and attributed to the stress induced decrease in switchable part of spontaneous polarization. This study clearly show that the applied stress had significant influence on the electrical properties of complex perovskite ceramics.

  18. Synthesis and photostabilizing performance of a polymeric HALS based on 1,2,2,6,6-pentamethylpiperidine and vinyl acetate

    Directory of Open Access Journals (Sweden)

    Marcelo Aparecido Chinelatto

    2015-01-01

    Full Text Available Abstract Polymeric hindered amine light stabilizers (polymeric HALS have been extensively studied because they combine a high ability to protect the polymers against harmful effects of weathering with minimum physical loss. In this study a new polymeric N-methylated HALS was synthesized by the radical copolymerization of a cyclic tertiary amine with vinyl acetate (VAc. 4-Acryloyloxy-1,2,2,6,6-pentamethylpiperidine (APP, the cyclic tertiary amine, was prepared by the initial conversion of 2,2,6,6-tetramethyl-4-piperidinol derivatives via two different routes. The APP/VAc copolymer synthesized was characterized by size exclusion chromatography (SEC, Fourier transform infrared spectroscopy (FTIR and carbon-13 nuclear magnetic resonance (13C NMR. The photostabilizing performance, particularly the induction period of polypropylene (PP films containing different concentrations of APP/VAc copolymer, when exposed to accelerated aging, was comparable to that of PP films compounded with commercial polymeric HALS.

  19. Reversible addition-fragmentation chain transfer polymerization in microemulsion.

    Science.gov (United States)

    O'Donnell, Jennifer M

    2012-04-21

    This tutorial review first details the uncontrolled microemulsion polymerization mechanism, and the RAFT polymerization mechanism to provide the necessary background for examining the RAFT microemulsion polymerization mechanism. The effect of the chain transfer agent per micelle ratio and the chain transfer agent aqueous solubility on the RAFT microemulsion polymerization kinetics, polymer molecular weight and polydispersity, and polymer nanoparticle size are discussed with a focus on oil-in-water microemulsions. Modeling of RAFT microemulsion polymerization kinetics and the resulting final polymer molecular weight are presented to assist with the analysis of observed experimental trends. Lastly, the current significance of RAFT microemulsion polymerization and the future directions are discussed. PMID:22246214

  20. Equilibrium polymerization on the equivalent-neighbor lattice

    Science.gov (United States)

    Kaufman, Miron

    1989-01-01

    The equilibrium polymerization problem is solved exactly on the equivalent-neighbor lattice. The Flory-Huggins (Flory, 1986) entropy of mixing is exact for this lattice. The discrete version of the n-vector model is verified when n approaches 0 is equivalent to the equal reactivity polymerization process in the whole parameter space, including the polymerized phase. The polymerization processes for polymers satisfying the Schulz (1939) distribution exhibit nonuniversal critical behavior. A close analogy is found between the polymerization problem of index the Schulz r and the Bose-Einstein ideal gas in d = -2r dimensions, with the critical polymerization corresponding to the Bose-Einstein condensation.

  1. Medical prototyping using two photon polymerization

    Directory of Open Access Journals (Sweden)

    Roger J Narayan

    2010-12-01

    Full Text Available Two photon polymerization involves nearly simultaneous absorption of ultrashort laser pulses for selective curing of photosensitive material. This process has recently been used to create small-scale medical devices out of several classes of photosensitive materials, such as acrylate-based polymers, organically-modified ceramic materials, zirconium sol-gels, and titanium-containing hybrid materials. In this review, the use of two photon polymerization for fabrication of several types of small-scale medical devices, including microneedles, artificial tissues, microfluidic devices, pumps, sensors, and valves, from computer models is described. Necessary steps in the development of two photon polymerization as a commercially viable medical device manufacturing method are also considered.

  2. Immobilization of Polymeric Luminophor on Nanoparticles Surface

    Science.gov (United States)

    Bolbukh, Yuliia; Podkoscielna, Beata; Lipke, Agnieszka; Bartnicki, Andrzej; Gawdzik, Barbara; Tertykh, Valentin

    2016-04-01

    Polymeric luminophors with reduced toxicity are of the priorities in the production of lighting devices, sensors, detectors, bioassays or diagnostic systems. The aim of this study was to develop a method of immobilization of the new luminophor on a surface of nanoparticles and investigation of the structure of the grafted layer. Monomer 2,7-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,7-NAF.DM) with luminophoric properties was immobilized on silica and carbon nanotubes in two ways: mechanical mixing with previously obtained polymer and by in situ oligomerization with chemisorption after carrier's modification with vinyl groups. The attached polymeric (or oligomeric) surface layer was studied using thermal and spectral techniques. Obtained results confirm the chemisorption of luminophor on the nanotubes and silica nanoparticles at the elaborated synthesis techniques. The microstructure of 2,7-NAF.DM molecules after chemisorption was found to be not changed. The elaborated modification approach allows one to obtain nanoparticles uniformly covered with polymeric luminophor.

  3. Molecular Probe Fluorescence Monitoring of Polymerization

    Science.gov (United States)

    Bunton, Patrick

    2002-01-01

    This project investigated the feasibility of using fluorescence spectroscopy to determine viscosity of polymer/monomer in support of Transient Interfacial Phenomena in Miscible Polymer Systems (TIPMPS). This project will attempt to measure gradient induced flow at a miscible interface during and / or after in-flight polymerization of dodecyl acrylate (lauryl acrylate). Concentration and temperature gradients will be intentionally introduced during polymerization and the resultant fluid flow determined by Particle Imaging Velocimetry (PIV). This report describes an investigation of the feasibility of using fluorescence of a probe molecule to monitor viscosity and/or concentration during and after polymerization. The probe used was pyrene which has been shown to be sensitive to its local environment in methyl methacrylate.

  4. Fruit and Vegetable Quality Assessment via Dielectric Sensing.

    Science.gov (United States)

    El Khaled, Dalia; Novas, Nuria; Gazquez, Jose A; Garcia, Rosa M; Manzano-Agugliaro, Francisco

    2015-01-01

    The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose. Moreover, a focused study of dielectric spectroscopy and advanced dielectric sensing is a highly interesting topic. This review explains the dielectric property basics and classifies the dielectric spectroscopy measurement techniques. It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions. An in-depth definition of dielectric spectroscopy and its usefulness in the electric characterization of food materials is presented, along with the various sensor techniques used for dielectric measurements. The collective data are tabulated in a summary of the dielectric findings in horticultural field investigations, which will facilitate more advanced and focused explorations in the future. PMID:26131680

  5. Influence of Cyclodextrin on the Styrene Polymerization

    Institute of Scientific and Technical Information of China (English)

    HU Jie; LIU Bai-ling

    2004-01-01

    Cyclodextrin (CD) are oligosaccharides consisting of 6( α ), 7( β ), 8( γ ) units of1,4-linked glucose. Due to their polar hydrophilic outer shell and relatively hydrophobic cavity, theyare able to build up host-guest complexes by inclusion of suitable hydrophobic molecules. Theformation of these complexes leads to significant changes of the solubility and reactivity of the guestmolecules, but without any chemical modification. Thus, water insoluble molecules may becomecompletely water soluble simply by mixing with an aqueous solution of native CD or CD-derivatives.Hydrogen bonds or hydrophobic interactions are responsible for the stability of the complexes and itturned out that the complexed monomers could be successfully polymerized by free radicalpolymerization in water.In our present work, using styrene as monomer, potassium peroxodisulfate as radical initiator thatreacted in water in the presence ofβ-CD but without any additional surfactant, the effect ofcyclodextrin on the polymerization was described. Additionally, the acceleration mechanism ofcyclodextrin in the polymerization was also explained based on dynamic study.Table 1 Effect of CD on the monomer reactivityIt is found that β -CD could greatly accelerate the polymerization, enhance the final conversion ofmonomer. And the more the amount of β-CD was introduced, the faster the polymerization wasobtained. From Figure 1, after 5 hours reaction at 80℃, the monomer conversion in the presence of1.0g cyclodextrin reached to 95%. However, that in absence of cyclodextrin was only 60%. And themonomer conversion was not to exceed 75% even reacted for 8 hours when no CD in reactionsystem.In order to describe the acceleration of CD in the polymerization quantitatively, based onCD and without CD. As shown in Table 1, CD produced significant effect on the monomer reactivity.The relative relativities of monomer were greatly increased with the increase of the amount of CD.

  6. Polymeric materials obtained by electron beam irradiation

    International Nuclear Information System (INIS)

    Research activities in the field of electron beam irradiation of monomer aqueous solution to produce polymeric materials used for waste waters treatment, agriculture and medicine are presented. The technologies and special features of these polymeric materials are also described. The influence of the chemical composition of the solution to ba irradiated, absorbed dose level and absorbed dose rate level are discussed. Two kinds of polyelectrolytes, PA and PV types and three kinds of hydrogels, pAAm, pAAmNa and pNaAc types, the production of which was first developed with IETI-10000 Co-60 source and then adapted to the linacs built in Accelerator Laboratory, are described. (author)

  7. Planar elongation of soft polymeric networks

    DEFF Research Database (Denmark)

    Jensen, Mette Krog; Hassager, Ole; Rasmussen, Henrik K.; Skov, Anne Ladegaard; Bach, Anders; Koldbech, Henning Vitus

    2010-01-01

    A new test fixture for the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks with application towards pressure-sensitive adhesives (PSAs). The concept of this new geometry is to elongate a tube-like sample by keeping the perimeter constant....... To validate this new technique, soft polymeric networks of poly(propylene oxide) (PPO) were investigated during deformation. Particle tracking and video recording were used to detect to what extent the imposed strain rate and the sample perimeter remained constant. It was observed that, by using an...

  8. The flat phase of quantum polymerized membranes

    CERN Document Server

    Coquand, O

    2016-01-01

    We investigate the flat phase of quantum polymerized phantom membranes by means of a nonperturbative renormalization group approach. We first implement this formalism for general quantum polymerized membranes and derive the flow equations that encompass both quantum and thermal fluctuations. We then deduce and analyze the flow equations relevant to study the flat phase and discuss their salient features : quantum to classical crossover and, in each of these regimes, strong to weak coupling crossover. We finally illustrate these features in the context of free standing graphene physics.

  9. Fiber optical beam shaping using polymeric structures

    Science.gov (United States)

    Rodrigues Ribeiro, R. S.; Queirós, R. B.; Guerreiro, A.; Ecoffet, C.; Soppera, O.; Jorge, P. A. S.

    2014-05-01

    A method to control the output intensity profile of optical fibers is presented. Using guided wave photopolymerization in multimode structures the fabrication with modal assisted shaping of polymeric micro lenses is demonstrated. Results showing that a given linear polarized mode can be selectively excited controlling the intensity distribution at the fiber tip are presented. This pattern is then reproduced in the polymeric micro structure fabricated at the fiber tip thus modulating its output intensity distribution. Such structures can therefore be used to obtain at the fiber tip predetermined intensity patterns for attaining optical trapping or patterned illumination.

  10. Dielectric effect on electric fields in the vicinity of the metal–vacuum–dielectric junction

    Energy Technology Data Exchange (ETDEWEB)

    Chung, M.S., E-mail: mschung@ulsan.ac.kr [Department of Physics, University of Ulsan, San 29, Muga, Ulsan 680-749 (Korea, Republic of); Mayer, A. [FUNDP, University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Miskovsky, N.M.; Weiss, B.L.; Cutler, P.H. [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2013-09-15

    The dielectric effect was theoretically investigated in order to describe the electric field in the vicinity of a junction of a metal, dielectric, and vacuum. The assumption of two-dimensional symmetry of the junction leads to a simple analytic form and to a systematic numerical calculation for the field. The electric field obtained for the triple junction was found to be enhanced or reduced according to a certain criterion determined by the contact angles and dielectric constant. Further numerical calculations of the dielectric effect show that an electric field can experience a larger enhancement or reduction for a quadruple junction than that achieved for the triple junction. It was also found that even though it changes slowly in comparison with the shape effect, the dielectric effect was noticeably large over the entire range of the shape change. - Highlights: ► This work explains how a very strong electric field can be produced due to the dielectric in the vicinity of metal–dielectric contact. ► This work deals with configurations which enhance electric fields using the dielectric effect. The configuration is a type of junction at which metal, vacuum and dielectric meet. ► This work suggests the criterion to determine whether field enhancement occurs or not in the triple junction of metal, vacuum and dielectric. ► This work suggests that a quadruple junction is more effective in enhancing the electric field than a triple junction. The quadruple junction is formed by an additional vacuum portion to the triple junction. ► This work suggests that a triple junction can be a breakthrough candidate for a cold electron source.

  11. Dielectric properties of binary solutions a data handbook

    CERN Document Server

    Akhadov, Y Y

    1980-01-01

    Dielectric Properties of Binary Solutions focuses on the investigation of the dielectric properties of solutions, as well as the molecular interactions and mechanisms of molecular processes that occur in liquids. The book first discusses the fundamental formulas describing the dielectric properties of liquids and dielectric data for binary systems of non-aqueous solutions. Topics include permittivity and dielectric dispersion parameters of non-aqueous solutions of organic and inorganic compounds. The text also tackles dielectric data for binary systems of aqueous solutions, including permittiv

  12. Radiolysis aging study of polycarbonate

    International Nuclear Information System (INIS)

    Aging behaviors of polycarbonate under gamma irradiation were investigated by mechanical testing, scanning electron microspectroscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, gel permeation chromatography and X-ray photoelectron spectroscopy. The results show that tensile strength, glass transition temperatures, molecular weights and number averaged polymerization degree of the polycarbonate decreased with the dose. The smooth degree of fracture surface increased with the dose. Radiation degradation kinetics revealed that the degradation of polycarbonate under gamma irradiation is random degradation. (authors)

  13. Techniques for laser welding polymeric devices.

    Science.gov (United States)

    Jones, I A

    2003-04-01

    Recent advances in laser techniques mean that lasers are now being considered as an alternative to vibration, ultrasonic, dielectric, hot plate or hot bar welding, and adhesive bonding of plastics. The techniques required to put laser welding methods into practice are described for medical devices, tubular systems, films and synthetic fabrics. PMID:12789697

  14. Use of high and low frequency dielectric measurements in the NDE of adhesively bonded composite joints

    Science.gov (United States)

    Pethrick, R. A.; Hayward, D.; McConnell, B. K.; Crane, R. L.

    2005-05-01

    Dielectric spectroscopy has been developed as a non-destructive technique for assessment of moisture content and structural integrity of adhesively bonded joints. Knowledge of these parameters is particularly crucial for the aerospace industry, since environmental degradation of adhesive joints presents a major limit on their utilization. High and low frequency measurements have been carried out on joints assembled from CFRP adherend, and a commercially available adhesive (AF 163-2K). The samples have been aged in deionised water at 75oC to chart the effect water ingress has on bond durability. In addition, some joints have been exposed to cryogenic temperatures to mimic the conditions joints experience whilst an aircraft is in flight. In this way it has been possible to determine the extent of degradation caused by freezing of water within the joint structure. Dielectric behaviour of the joints was studied in both the frequency and in the time domain. Frequency domain analysis allows the amount and effects of moisture ingress in the bondline to be assessed, whereas the time domain highlights the onset of joint defects with increasing exposure time. Mechanical testing of the joints has been carried out to enable correlation between changes in strength and failure mechanism due to moisture ingress, with changes in the dielectric data. In addition, dielectric studies of the neat adhesive have been undertaken, as have gravimetric and dynamic mechanical thermal analysis. These have helped reveal the effects of ageing upon the adhesive layer itself.

  15. Evaluation of high temperature capacitor dielectrics

    Science.gov (United States)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  16. Electromechanical stability of compressible dielectric elastomer actuators

    International Nuclear Information System (INIS)

    The constitutive relation and the electromechanical stability of Varga–Blatz–Ko-type compressible isotropic dielectric elastomers undergoing large deformation are investigated in this paper. Free energy in any form, which consists of elastic strain energy and electric field energy, can be applied to analyze the electromechanical stability of dielectric elastomers. The constitutive relation and the electromechanical stability are analyzed by applying a new kind of free energy model, which consists of elastic strain energy, composed of the Varga model as the volume conservative energy and the Blatz–Ko model as the volume non-conservative energy, and electric field energy with constant permittivity. The ratio between the principal planar stretches, the ratio between the thickness and length direction stretches, and the power exponent of the stretch are defined to characterize the mechanical loading behavior and compressible behavior of the dielectric elastomer. Along with the increase of these parameters, which determine the shape or volume of the elastomer, and the Poisson ratio, the critical nominal electric field is higher, which indicates a more stable dielectric elastomer electromechanical system. In contrast, with the decrease of the dimensionless material parameter α of the Varga elastic strain energy, the critical nominal electric field increases. The coupling system becomes more stable. We further demonstrate that the critical nominal electric field of the compressible dielectric elastomer electromechanical coupling system is significantly influenced by the ratio between the principal planar stretches

  17. Dielectric Genome of van der Waals Heterostructures.

    Science.gov (United States)

    Andersen, Kirsten; Latini, Simone; Thygesen, Kristian S

    2015-07-01

    Vertical stacking of two-dimensional (2D) crystals, such as graphene and hexagonal boron nitride, has recently lead to a new class of materials known as van der Waals heterostructures (vdWHs) with unique and highly tunable electronic properties. Ab initio calculations should in principle provide a powerful tool for modeling and guiding the design of vdWHs, but in their traditional form such calculations are only feasible for commensurable structures with a few layers. Here we show that the dielectric properties of realistic, incommensurable vdWHs comprising hundreds of layers can be efficiently calculated using a multiscale approach where the dielectric functions of the individual layers (the dielectric building blocks) are computed ab initio and coupled together via the long-range Coulomb interaction. We use the method to illustrate the 2D-3D transition of the dielectric function of multilayer MoS2 crystals, the hybridization of quantum plasmons in thick graphene/hBN heterostructures, and to demonstrate the intricate effect of substrate screening on the non-Rydberg exciton series in supported WS2. The dielectric building blocks for a variety of 2D crystals are available in an open database together with the software for solving the coupled electrodynamic equations. PMID:26047386

  18. Polymerization Initiated at the Sidewalls of Carbon Nanotubes

    Science.gov (United States)

    Tour, James M.; Hudson, Jared L.

    2011-01-01

    A process has been developed for growing polymer chains via anionic, cationic, or radical polymerization from the side walls of functionalized carbon nanotubes, which will facilitate greater dispersion in polymer matrices, and will greatly enhance reinforcement ability in polymeric material.

  19. Immobilization of biocatalysts for enzymatic polymerizations : Possibilities, advantages, applications

    NARCIS (Netherlands)

    Miletic, Nemanja; Nastasovic, Aleksandra; Loos, Katja; Miletić, Nemanja; Nastasović, Aleksandra

    2012-01-01

    Biotechnology also holds tremendous opportunities for realizing functional polymeric materials. Biocatalytic pathways to polymeric materials are an emerging research area with not only enormous scientific and technological promise, but also a tremendous impact on environmental issues. Many of the en

  20. Aging Skin

    Science.gov (United States)

    ... email address Submit Home > Healthy Aging > Wellness Healthy Aging Aging skin More information on aging skin When it ... treated early. Return to top More information on Aging skin Read more from womenshealth.gov Varicose Veins ...

  1. Quantum cascade laser based monitoring of CF{sub 2} radical concentration as a diagnostic tool of dielectric etching plasma processes

    Energy Technology Data Exchange (ETDEWEB)

    Hübner, M.; Lang, N.; Röpcke, J.; Helden, J. H. van, E-mail: jean-pierre.vanhelden@inp-greifswald.de [Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff Str. 2, 17489 Greifswald (Germany); Zimmermann, S.; Schulz, S. E. [Fraunhofer Institute for Electronic Nano Systems, Technologie-Campus 3, 09126 Chemnitz (Germany); Buchholtz, W. [GLOBALFOUNDRIES Dresden Module One LLC and Co. KG, Wilschdorfer Landstr. 101, 01109 Dresden (Germany)

    2015-01-19

    Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF{sub 2} radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF{sub 2} radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm{sup −1}. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ν{sub 3} fundamental band of CF{sub 2} with the aid of an improved simulation of the line strengths. We found that the CF{sub 2} radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing.

  2. Polymerization of epoxy resins studied by positron annihilation

    International Nuclear Information System (INIS)

    The polymerization process of epoxy resins (bisphenol-A dicyanate) was studied using positron-annihilation spectroscopy. The polymerization from monomer to polymer through a polymerization reaction was followed by positron-annihilation lifetime spectroscopy measurements. Resins kept at curing temperatures (120, 150 and 200 oC) changed form from of powder to a solid through a liquid. The size of the intermolecular spaces of the solid samples increased along with the progress of polymerization. (author)

  3. Synthesis of glycopolymer architectures by reversible-deactivation radical polymerization

    OpenAIRE

    Ali Ghadban; Luca Albertin

    2013-01-01

    This review summarizes the state of the art in the synthesis of well-defined glycopolymers by Reversible-Deactivation Radical Polymerization (RDRP) from its inception in 1998 until August 2012. Glycopolymers architectures have been successfully synthesized with four major RDRP techniques: Nitroxide-mediated radical polymerization (NMP), cyanoxyl-mediated radical polymerization (CMRP), atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polym...

  4. Threshold Particle Diameters in Miniemulsion Reversible-Deactivation Radical Polymerization

    OpenAIRE

    Hidetaka Tobita

    2011-01-01

    Various types of controlled/living radical polymerizations, or using the IUPAC recommended term, reversible-deactivation radical polymerization (RDRP), conducted inside nano-sized reaction loci are considered in a unified manner, based on the polymerization rate expression, Rp = kp[M]K[Interm]/[Trap]. Unique miniemulsion polymerization kinetics of RDRP are elucidated on the basis of the following two factors: (1) A high single molecule concentration in a nano-sized particle; and (2) a signifi...

  5. Thermal Polymerization of Acrylamide by Differential Scanning Calorimetry

    OpenAIRE

    Kishore, K.; Santhanalakshmi, KN

    1981-01-01

    Thermal polymerization of acrylamide was studied by differential scanning calorimetry. Latent heat of fusion \\bigtriangleup Hf and enthalpy of polymerization \\bigtriangleup Hp values were found to be 36 and $-18.0 kcal mol^{-1}$, respectively. The overall activation energy E for the polymerization was calculated to be $19 k cal mol^{-1}$ up to 60% conversion. The added free-radical inhibitor (benzoquinone) was found to desensitize the thermal polymerization of acrylamide suggesting the polyme...

  6. Measurement and Analysis of in vitro Actin Polymerization

    OpenAIRE

    Doolittle, Lynda K.; Rosen, Michael K.; Padrick, Shae B.

    2013-01-01

    The polymerization of actin underlies force generation in numerous cellular processes. While actin polymerization can occur spontaneously, cells maintain control over this important process by preventing actin filament nucleation and then allowing stimulated polymerization and elongation by several regulated factors. Actin polymerization, regulated nucleation and controlled elongation activities can be reconstituted in vitro, and used to probe the signaling cascades cells use to control when ...

  7. Polymeric components for telecom and datacom

    NARCIS (Netherlands)

    Diemeer, Mart; Dekker, Ronald; Hilderink, Lucie; Leinse, Arne; Balakrishnan, Muralidharan; Faccini, Mirko; Driessen, Alfred; Lambeck, Paul V.; Gorecki, Christophe; Pustelny, Tadeusz

    2005-01-01

    Polymeric optical waveguide components offer attractive properties for applications in optical telecom and datacom systems. These are high speed for electro-optic modulators, low power dissipation for thermo-optic (digital) switches and low-cost for all active and passive components. We report on ac

  8. Vinyl acetate polymerization by ionizing radiation

    International Nuclear Information System (INIS)

    The aim of this work is the synthesis and characterization of the poly(vinyl acetate) using the ionizing radiation. Six polymerizations of vinyl acetate were carried out using three techniques of polymerization: in bulk, emulsion and solution. In the technique of solution polymerization were used two solvents, the alcohol ethyl and the methylethylketone, in two proportions 1:0.5 and 1:1 related to the monomer. The solutions were irradiated with gamma rays from a 60Co source, with dose rate between 5.25 kGy/h and 6.26 kGy/h. The polymers obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The glass transition temperature (Tg) was investigated by Differential Scanning Calorimeter (DSC). The molecular weight was analyzed by the technique of Gel Permeation Chromatography (GPC). Tests of density, hardness and Vicat softening temperature were carried out. The infrared spectroscopy and others results confirmed that the polymers obtained by polymerization of vinyl acetate in bulk, emulsion and solution, using ionizing radiation, really correspond at poly(vinyl acetate). (author)

  9. Nylon 6 polymerization in the solid state

    NARCIS (Netherlands)

    Gaymans, Reinoud J.; Amirtharaj, John; Kamp, Henk

    1982-01-01

    The postcondensation of nylon 6 in the solid state was studied. The reactions were carried out on fine powder in a fluidized bed reactor in a stream of dry nitrogen in the temperature range 110-205°C and during 1-24 h. The solid-state polymerization (SSP) did not follow melt kinetics, but was found

  10. Characteristic emission in glutaraldehyde polymerized hemoglobin

    International Nuclear Information System (INIS)

    Hemoglobin with different modifications has been investigated using spectroscopic techniques. A new emission at around 371 nm has been observed under excitation of 305 nm from glutaraldehyde polymerized human hemoglobin. Intensity and peak position of the emission are dependent on both oxidation state and ligand environment and the emission has been identified from the hemoglobin oligomer.

  11. Molecularly imprinted polymeric beads for catalysis

    Czech Academy of Sciences Publication Activity Database

    Strikovsky, A. G.; Wulff, G.; Hradil, Jiří; Green, B. S.

    Praha : Institute of Macromolecular Chemistry , Academy of Sciences of the Czech Republic, 1999. s. P8. ISBN 80-85009-35-8. [Microsymposium: Advances in Polymerization Methods: Controlled Synthesis of Functionalized Polymers /39./. 12.07.1999-15.07.1999, Praha] Subject RIV: CD - Macromolecular Chemistry

  12. Forming of Polymeric Tubular Micro-components

    DEFF Research Database (Denmark)

    Qin, Yi; Zhao, Jie; Anyasodor, Gerald; Schütt Hansen, Klaus; Calderon, Ivan; Konrad, Konstantin; Hartl, Christoph; Arentoft, Mogens; Chronakis, Ioannis S.

    2015-01-01

    This chapter is intended to provide an overview of three nontraditional shaping technologies for the forming of polymeric micro-tubes, which are hot embossing, blow molding, and cross rolling, as well as realization of a process chain and the integration of a modular machine-based manufacturing p...

  13. Polymeric components for telecom and datacom

    Science.gov (United States)

    Diemeer, Mart; Dekker, Ronald; Hilderink, Lucie; Leinse, Arne; Balakrishnan, Muralidharan; Faccini, Mirko; Driessen, Alfred

    2005-09-01

    Polymeric optical waveguide components offer attractive properties for applications in optical telecom and datacom systems. These are high speed for electro-optic modulators, low power dissipation for thermo-optic (digital) switches and low-cost for all active and passive components. We report on active and passive components realized by utilizing polymer-specific attractive techniques such as planarizing spincoating, low-temperature reflowing and direct photodefinition. Examples are multimode photodefined passive polymeric waveguides for optical interconnect applications; photodefined monomode polymeric waveguides loaded with rare-earth doped nanoparticles for planar waveguide amplifiers and with non-linear chromophores for electro-optic modulators. We will show that polymer waveguide technology allows vertical stacking of electro-optic microringresonators with their port waveguides to realize high-speed modulators. By reflowing the reactive-ion-etched microring we could reduce the scattering by wall roughness considerably. Thermo-optic polymeric microringresonators combine the high thermo-optic coefficient and low thermal conductivity of polymers with the small size of the microring. It will be shown that this yields a broad wavelength tuning range at low power dissipation.

  14. Next-generation polymeric photonic devices

    Science.gov (United States)

    Eldada, Louay A.; Shacklette, Lawrence W.; Norwood, Robert A.; Yardley, James T.

    1997-07-01

    A versatile polymeric waveguide technology is proposed for low-cost high-performance photonic devices that address the needs of both the telecom and the datacom industries. We have developed advanced organic polymeric materials that can be readily made into both multimode and single-mode optical waveguide structures of controlled numerical aperture and geometry. These materials are formed from highly-crosslinked acrylate monomers with specific linkages that determine properties such as flexibility, toughness, loss, and stability with temperature and humidity. These monomers are intermiscible, providing for precise adjustment of the refractive index from 1.3 to 1.6. Waveguides are formed photolithographically, with the liquid monomer mixture polymerizing upon illumination in the UV via either mask exposure or laser direct-writing. A wide range of rigid and flexible substrates can be used, including glass, quartz, oxidized silicon, glass-filled epoxy printed circuit board substrate, and flexible polyimide film. We discuss the use of these materials on chips, on multi-chip modules, on boards, and on backplanes. Light coupling from and to chips is achieved by cutting 45 degree(s) mirrors using excimer laser ablation. Fabrication of the planar polymeric structures directly on the modules provides for stability, ruggedness, and hermeticity in packaging.

  15. On viscoelastic instability in polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    The 3D Lagrangian Integral Method is used to simulate the effects of surface tension on the viscoelastic end-plate instability, occuring in the rapid extension of some polymeric filaments between parallel plates. It is shovn that the surface tension delays the onset of the instability. Furthermore...

  16. Gamma Radiation-Induced Template Polymerization Technique

    International Nuclear Information System (INIS)

    Gamma radiation induced copolymerization of acrylamide sodiumacrylate (AM-AANa) in the presence and absence of the polymer additive was studied at low monomer concentration(1.4M/l). The results showed that the exponents of the dose rate for the polymerization rate was found to be 1.3 and 1.4 in the absence and in the presence of the polymer additive respectively. The molecular weight of the formed polymer increased by addition of the polymer to the system. In the presence of the polymer the comonomers polymerize on the added polymer. In the absence of the added polymer the comonomers polymerize according to the copolymerization process at the initial stage of the copolymerization. While at high conversion the residual comonomers polymerize on the formed macromolecular chains of the produced polymer. These studies showed that the copolymerization in the presence of added polymer is completely template copolymerization while in the absence of the polymer the copolymerization process is only template process with a high conversion

  17. Radiation-induced polymerization of acrylated systems

    International Nuclear Information System (INIS)

    Complete text of publication follows. It has been generally accepted that ionizing radiation induces free radical polymerization in acrylate compounds. It is also reported that, following primary ionization events, acrylates and methacrylates scavenge thermalized electrons to give rise to radical anions and radical cations, which undergo reactions producing the corresponding free radicals. Acrylates have received the most attention in radiation curable pressure sensitive adhesives (PSAs). 2-EHA is well known for its unique pressure-sensitive adhesive properties. An understanding of its primary mechanism of polymerization is of industrial as well as fundamental interest. High entanglement and high molecular weight between crosslinks are crucial for the high shear and peel strength, required of PSAs. Such polymers may be formed using thermal and UV-initiation in solvent or emulsion. Electron beam can also provide these properties when the monomer is polymerized at moderate dose rates and at low temperature. Pulsed electron beam provides a special advantage under conditions where the dose per pulse is below the threshold for overlap (ca. 40 Gy/pulse) and the pulse rate is high enough (>1 kHz) to maintain a quasi-heterogeneous mode at high doses rates. Maintaining low temperature in the early stages of polymerization is important in achieving good properties

  18. Operating Modes Of Chemical Reactors Of Polymerization

    OpenAIRE

    Meruyert Berdieva; Aiman Ospanova; Madina Koshkinbayeva; Tamara Zhukabayeva

    2012-01-01

    In the work the issues of stable technological modes of operation of main devices of producing polysterol reactors have been researched as well as modes of stable operation of a chemical reactor have been presented, which enables to create optimum mode parameters of polymerization process, to prevent emergency situations of chemical reactor operation in industrial conditions.

  19. Operating Modes Of Chemical Reactors Of Polymerization

    Directory of Open Access Journals (Sweden)

    Meruyert Berdieva

    2012-05-01

    Full Text Available In the work the issues of stable technological modes of operation of main devices of producing polysterol reactors have been researched as well as modes of stable operation of a chemical reactor have been presented, which enables to create optimum mode parameters of polymerization process, to prevent emergency situations of chemical reactor operation in industrial conditions.

  20. Fingerprinting the thermal history of polymeric materials

    International Nuclear Information System (INIS)

    Knowledge of temperatures experienced by a polymeric material in storage or in the field helps predict the useful life or remaining service life of the parent component. This report describes a nondestructive test procedure to characterize the maximum temperature and time-at-temperature of semicrystalline polymers commonly used in electrical cable insulations and as parts of other components

  1. Superparamagnetic nanoparticles stabilized by polymerized PEGylated coatings

    International Nuclear Information System (INIS)

    Novel superparamagnetic iron oxide nanoparticles coated with polymerized PEGylated bilayers were prepared. Bilayers composed of 10-undecenoic acid (UD) inner and UDPEG (PEG ester of UD) outer layers are resistant to aggregation after γ-irradiation. Various methods of coating were developed to prepare small (60-100nm) and ultrasmall (20-35nm) particles without size separation processes

  2. Biodegradable Polymeric Microcapsules: Preparation and Properties

    NARCIS (Netherlands)

    Sawalha, H.I.M.; Schroën, C.G.P.H.; Boom, R.M.

    2011-01-01

    Biodegradable polymeric microcapsules can be produced through different methods of which emulsion solvent-evaporation/extraction is frequently used. In this technique, the polymer (often polylactide) is dissolved in a good solvent and is emulsified together with a poor solvent into a nonsolvent phas

  3. Immobilization of Trichoderma reesei by radiation polymerization

    International Nuclear Information System (INIS)

    Immobilization of Trichoderma reesei was carried out by radiation polymerization. It was found that the activity of fixed cells increased with increasing surface area of the carrier and was affected by the concentration of monomer tetraethylenglycol dimethacrylate and the shape of the substrate composition and structure of cotton textile fabrics. (author)

  4. Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

    International Nuclear Information System (INIS)

    Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

  5. A Route Towards Sustainability Through Engineered Polymeric Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Reeja-Jayan, B; Kovacik, P; Yang, R; Sojoudi, H; Ugur, A; Kim, DH; Petruczok, CD; Wang, XX; Liu, AD; Gleason, KK

    2014-05-30

    Chemical vapor deposition (CVD) of polymer films represent the marriage of two of the most important technological innovations of the modern age. CVD as a mature technology for growing inorganic thin films is already a workhorse technology of the microfabrication industry and easily scalable from bench to plant. The low cost, mechanical flexibility, and varied functionality offered by polymer thin films make them attractive for both macro and micro scale applications. This review article focuses on two energy and resource efficient CVD polymerization methods, initiated Chemical Vapor Deposition (iCVD) and oxidative Chemical Vapor Deposition (oCVD). These solvent-free, substrate independent techniques engineer multi-scale, multi-functional and conformal polymer thin film surfaces and interfaces for applications that can address the main sustainability challenges faced by the world today.

  6. Terajets produced by 3D dielectric cuboids

    CERN Document Server

    Pacheco-Peña, V; Minin, I V; Minin, O V

    2014-01-01

    The capability of generating terajets using 3D dielectric cuboids working at terahertz (THz) frequencies (as analogues of nanojets in the infrared band) are introduced and studied numerically. The focusing performance of the terajets are evaluated in terms of the transversal full width at half maximum along x- and y- directions using different refractive indexes for a 3D dielectric cuboid with a fixed geometry, obtaining a quasi-symmetric terajet with a subwavelength resolution of ~0.46{\\lambda}0 when the refractive index is n = 1.41. Moreover, the backscattering enhancement produced when metal particles are introduced in the terajet region is demonstrated for a 3D dielectric cuboid and compared with its 2D counterpart. The results of the jet generated for the 3D case are experimentally validated at sub-THz waves, demonstrating the ability to produce terajets using 3D cuboids.

  7. Studies on metal-dielectric plasmonic structures.

    Energy Technology Data Exchange (ETDEWEB)

    Chettiar, Uday K. (Purdue University, West Lafayette, IN); Liu, Zhengtong (Purdue University, West Lafayette, IN); Thoreson, Mark D. (Purdue University, West Lafayette, IN); Shalaev, Vladimir M. (Purdue University, West Lafayette, IN); Drachev, Vladimir P. (Purdue University, West Lafayette, IN); Pack, Michael Vern; Kildishev, Alexander V. (Purdue University, West Lafayette, IN); Nyga, Piotr (Purdue University, West Lafayette, IN)

    2010-01-01

    The interaction of light with nanostructured metal leads to a number of fascinating phenomena, including plasmon oscillations that can be harnessed for a variety of cutting-edge applications. Plasmon oscillation modes are the collective oscillation of free electrons in metals under incident light. Previously, surface plasmon modes have been used for communication, sensing, nonlinear optics and novel physics studies. In this report, we describe the scientific research completed on metal-dielectric plasmonic films accomplished during a multi-year Purdue Excellence in Science and Engineering Graduate Fellowship sponsored by Sandia National Laboratories. A variety of plasmonic structures, from random 2D metal-dielectric films to 3D composite metal-dielectric films, have been studied in this research for applications such as surface-enhanced Raman sensing, tunable superlenses with resolutions beyond the diffraction limit, enhanced molecular absorption, infrared obscurants, and other real-world applications.

  8. Multimode directionality in all-dielectric metasurfaces

    CERN Document Server

    Yang, Yuanqing; Kostinski, Sarah V; Odit, Mikhail; Kapitanova, Polina; Qiu, Min; Kivshar, Yuri

    2016-01-01

    All-dielectric resonant nanophotonics has emerged recently as a new direction of research aiming at the manipulation of strong optically-induced electric and magnetic Mie resonances in dielectric nanoparticles with high refractive index, for a design of metadevices with reduced dissipative losses and large resonant enhancement of both electric and magnetic fields. Usually, the geometry of dielectric nanoparticles is considered to be close to either sphere or rod, so the exact Mie solutions of the scattering problem are applied. Here we study nanoparticles with a large aspect ratio (such as nanobars) and describe a novel type of hybrid Mie-Fabry-Perot modes responsible for the existence of multiple magnetic dipole resonances. The multiple magnetic dipoles originate from a combination of a magnetic dipolar mode and a number of standing waves of an elongated anisotropic nanobar. We reveal that these novel hybrid modes can interfere constructively with the induced electric dipoles and thereby lead to multimode un...

  9. Broadband Dielectric Spectroscopy on Human Blood

    CERN Document Server

    Wolf, M; Lunkenheimer, P; Loidl, A

    2011-01-01

    Dielectric spectra of human blood reveal a rich variety of dynamic processes. Achieving a better characterization and understanding of these processes not only is of academic interest but also of high relevance for medical applications as, e.g., the determination of absorption rates of electromagnetic radiation by the human body. The dielectric properties of human blood are studied using broadband dielectric spectroscopy, systematically investigating the dependence on temperature and hematocrit value. By covering a frequency range from 1 Hz to 40 GHz, information on all the typical dispersion regions of biological matter is obtained. We find no evidence for a low-frequency relaxation (alpha-relaxation) caused, e.g., by counterion diffusion effects as reported for some types of biological matter. The analysis of a strong Maxwell-Wagner relaxation arising from the polarization of the cell membranes in the 1-100 MHz region (beta-relaxation) allows for the test of model predictions and the determination of variou...

  10. Dielectric and phase behavior of dipolar spheroids.

    Science.gov (United States)

    Johnson, Lewis E; Benight, Stephanie J; Barnes, Robin; Robinson, Bruce H

    2015-04-23

    The Stockmayer fluid, composed of dipolar spheres, has a well-known isotropic-ferroelectric phase transition at high dipole densities. However, there has been little investigation of the ferroelectric transition in nearly spherical fluids at dipole densities corresponding to those found in many polar solvents and in guest-host organic electro-optic materials. In this work, we examine the transition to ordered phases of low-aspect-ratio spheroids under both unperturbed and poled conditions, characterizing both the static dielectric response and thermodynamic properties of spheroidal systems. Spontaneous ferroelectric ordering was confined to a small region of aspect ratios about unity, indicating that subtle changes in sterics can have substantial influence on the behavior of coarse-grained liquid models. Our results demonstrate the importance of molecular shape in obtaining even qualitatively correct dielectric responses and provide an explanation for the success of the Onsager model as a phenomenological representation for the dielectric behavior of polar organic liquids. PMID:25821921

  11. On equilibrium charge distribution above dielectric surface

    Directory of Open Access Journals (Sweden)

    Yu.V. Slyusarenko

    2009-01-01

    Full Text Available The problem of the equilibrium state of the charged many-particle system above dielectric surface is formulated. We consider the case of the presence of the external attractive pressing field and the case of its absence. The equilibrium distributions of charges and the electric field, which is generated by these charges in the system in the case of ideally plane dielectric surface, are obtained. The solution of electrostatic equations of the system under consideration in case of small spatial heterogeneities caused by the dielectric surface, is also obtained. These spatial inhomogeneities can be caused both by the inhomogeneities of the surface and by the inhomogeneous charge distribution upon it. In particular, the case of the "wavy" spatially periodic surface is considered taking into account the possible presence of the surface charges.

  12. TE resonances in graphene-dielectric structures

    CERN Document Server

    Werra, Julia F M; Busch, Kurt

    2015-01-01

    An investigation of the dispersion relations of TE resonances in different graphene-dielectric structures is presented. When a graphene layer is brought into contact with a dielectric material, a gap can appear in its electric band structure. This allows for the formation of TE-plasmons with unusual dispersion relations. In addition, if the dielectric has a finite thickness, graphene acts as a mode filter and strongly modifies the behavior of the waveguiding modes by introducing a frequency cutoff. This cutoff and the properties of TE-plasmons are closely related to the pair-creation threshold of graphene thus representing quantum mechanical effects that manifest themselves in the electromagnetic response. Our findings are of particular relevance to all forms of light-matter interaction in graphene-based systems, notably for the decay rates of emitters that are in close proximity to graphene.

  13. High efficiency dielectric metasurfaces at visible wavelengths

    CERN Document Server

    Devlin, Robert C; Chen, Wei-Ting; Oh, Jaewon; Capasso, Federico

    2016-01-01

    Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics1-3. Dielectric metasurfaces demonstrated thus far4-10 are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. It is critical that new materials and fabrication techniques be developed for dielectric metasurfaces at visible wavelengths to enable applications such as three-dimensional displays, wearable optics and planar optical systems11. Here, we demonstrate high performance titanium dioxide dielectric metasurfaces in the form of holograms for red, green and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide that exhibits low surface roughness of 0.738 nm and ideal optical properties. To fabricate the metasurfaces we use a lift-off-like process that allows us to produce highly anisotropic nanofins with shape birefringence. This ...

  14. Novel Low Temperature Co-Fired Ceramic Material System Composed of Dielectrics with Different Dielectric Constants

    Science.gov (United States)

    Sakamoto, Sadaaki; Adachi, Hiroshige; Kaneko, Kazuhiro; Sugimoto, Yasutaka; Takada, Takahiro

    2013-09-01

    We found that the co-firing low temperature co-fired ceramic (LTCC) materials of different dielectric constants (ɛr) with Cu wiring is achievable using a novel, original design. It was confirmed that the dielectric characteristics of the dielectrics designed in this study are very suitable for the use of the dielectrics in electronic components such as filters mounted in high-speed radio communication equipment. The dielectric constants of the lower- and higher-dielectric-coefficient materials were 8.1 and 44.5, respectively, which are sufficiently effective for downsizing LTCC components. Observing the co-fired interface, it was confirmed that excellent co-firing conditions resulted in no mechanical defects such as delamination or cracks. On the basis of the results of wavelength dispersive X-ray spectrometry (WDX) and X-ray diffractometry (XRD), it was confirmed that co-firing with minimal interdiffusion was realized using the same glass for both dielectrics. It is concluded that the materials developed are good for co-firing in terms of the mechanical defects and interdiffusion that appear in them.

  15. 21 CFR 872.6070 - Ultraviolet activator for polymerization.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet activator for polymerization. 872.6070 Section 872.6070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... polymerization. (a) Identification. An ultraviolet activator for polymerization is a device that...

  16. Mechanism and Modeling for Polymerization of Acrylamide in Inverse Microemulsions

    Institute of Scientific and Technical Information of China (English)

    LiXiao; ZhangWeiying; YuanHuigen

    2004-01-01

    After discussion on the mechanism of polymer particle nucleation and growth in inverse microemulsion polymerization, a schematic physical model for polymerization of acrylamide in inverse microemulsions was presented. Furthermore, several key problems in mathematically modeling of inverse microemulsion polymerization were pointed out.

  17. Dielectric loss against piezoelectric power harvesting

    International Nuclear Information System (INIS)

    Piezoelectricity is one of the most popular electromechanical transduction mechanisms for constructing kinetic energy harvesting systems. When a standard energy harvesting (SEH) interface circuit, i.e., bridge rectifier plus filter capacitor, is utilized for collecting piezoelectric power, the previous literature showed that the power conversion can be well predicted without much consideration for the effect of dielectric loss. Yet, as the conversion power gets higher by adopting power-boosting interface circuits, such as synchronized switch harvesting on inductor (SSHI), the neglect of dielectric loss might give rise to deviation in harvested power estimation. Given the continuous progress on power-boosting interface circuits, the role of dielectric loss in practical piezoelectric energy harvesting (PEH) systems should receive attention with better evaluation. Based on the integrated equivalent impedance network model, this fast track communication provides a comprehensive study on the susceptibility of harvested power in PEH systems under different conditions. It shows that, dielectric loss always counteracts piezoelectric power harvesting by causing charge leakage across piezoelectric capacitance. In particular, taking corresponding ideal lossless cases as references, the counteractive effect might be aggravated under one of the five conditions: larger dielectric loss tangent, lower vibration frequency, further away from resonance, weaker electromechanical coupling, or using power-boosting interface circuit. These relationships are valuable for the study of PEH systems, as they not only help explain the role of dielectric loss in piezoelectric power harvesting, but also add complementary insights for material, structure, excitation, and circuit considerations towards holistic evaluation and design for practical PEH systems. (fast track communications)

  18. Method for fabrication of crack-free ceramic dielectric films

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Beihai; Narayanan, Manoj; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan

    2016-05-31

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprises the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. The process provides a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  19. Method for fabrication of crack-free ceramic dielectric films

    Science.gov (United States)

    Ma, Beihai; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan; Narayanan, Manoj

    2014-02-11

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprise the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. Also provided was a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  20. Signal amplification strategies for DNA and protein detection based on polymeric nanocomposites and polymerization: A review

    International Nuclear Information System (INIS)

    Highlights: • We review the innovative advances in polymer-based signal amplification. • Conceptual connectivity between different amplified methodologies is illustrated. • Examples explain the mechanisms of polymers/polymerizations-based amplification. • Several elegant applications are summarized that illustrate underlying concept. - Abstract: Demand is increasing for ultrasensitive bioassays for disease diagnosis, environmental monitoring and other research areas. This requires novel signal amplification strategies to maximize the signal output. In this review, we focus on a series of significant signal amplification strategies based on polymeric nanocomposites and polymerization. Some common polymers are used as carriers to increase the local concentration of signal probes and/or biomolecules on their surfaces or in their interiors. Some polymers with special fluorescence and optical properties can efficiently transfer the excitation energy from a single site to the whole polymer backbone. This results in superior fluorescence signal amplification due to the resulting collective effort (integration of signal). Recent polymerization-based signal amplification strategies that employ atom transfer radical polymerization (ATRP) and photo-initiated polymerization are also summarized. Several distinctive applications of polymers in ultrasensitive bioanalysis are highlighted

  1. NATO Advanced Study Institute on Ring-opening Metathesis Polymerization of Olefins and Polymerization of Alkynes

    CERN Document Server

    1998-01-01

    The first NATO Advanced Study Institute on Olefin Metathesis and Polymerization Catalysts was held on September 10-22, 1989 in Akcay, Turkey. Based on the fundamental research of RRSchrock, RGrubbs and K.B.Wagener in the field of ring opening metathesis polymerization (ROMP), acyclic diene metathesis (ADMET) and alkyne polymerization, these areas gained growing interest within the last years. Therefore the second NATO-ASI held on metathesis reactions was on Ring Opening Metathesis Po­ lymerization of Olefins and Polymerization of Alkynes on September 3-16, 1995 in Akcay, Turkey. The course joined inorganic, organic and polymer chemists to exchange their knowledge in this field. This volume contains the main and short lectures held in Akcay. To include ADMET reactions better into the title of this volume we changed it into: Metathesis Polymerization of Olefins and Alkyne Polymerization. This volume is addressed to research scientists, but also to those who start to work in the area of olefin metathesis and al...

  2. Signal amplification strategies for DNA and protein detection based on polymeric nanocomposites and polymerization: A review

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shaohong; Yuan, Liang; Hua, Xin; Xu, Lingling; Liu, Songqin, E-mail: liusq@seu.edu.cn

    2015-06-02

    Highlights: • We review the innovative advances in polymer-based signal amplification. • Conceptual connectivity between different amplified methodologies is illustrated. • Examples explain the mechanisms of polymers/polymerizations-based amplification. • Several elegant applications are summarized that illustrate underlying concept. - Abstract: Demand is increasing for ultrasensitive bioassays for disease diagnosis, environmental monitoring and other research areas. This requires novel signal amplification strategies to maximize the signal output. In this review, we focus on a series of significant signal amplification strategies based on polymeric nanocomposites and polymerization. Some common polymers are used as carriers to increase the local concentration of signal probes and/or biomolecules on their surfaces or in their interiors. Some polymers with special fluorescence and optical properties can efficiently transfer the excitation energy from a single site to the whole polymer backbone. This results in superior fluorescence signal amplification due to the resulting collective effort (integration of signal). Recent polymerization-based signal amplification strategies that employ atom transfer radical polymerization (ATRP) and photo-initiated polymerization are also summarized. Several distinctive applications of polymers in ultrasensitive bioanalysis are highlighted.

  3. On the discovery of some phenomena in electrochemical etching of polymeric dosimeters

    International Nuclear Information System (INIS)

    Although electrochemical etching (ECE) of polymeric dosimeters has been advancing for over a decade, some phenomena such as 'dielectric loss', 'electro-osmosis', 'dielectrophoresis' and 'electrostriction' have been recently discovered and proved to exist in ECE which are reported and discussed in this paper. The 'dielectric loss' mechanisms lead to an internal heating effect which heats up the etchant effectively with a rate per unit foil volume proportional to E2, f, and polymer loss index (ε' tan δ). Thus foil effective diameter, etchant volume, and the chamber's external insulation were introduced as new important parameters in ECE especially at high applied field conditions. The combined effects of 'electro-osmotic pressure' and 'dielectrophoretic forces' are discussed to cause 'water tree' microstructure of tracks in CR-39 with a 'water bubble' at the center which has a temporary nature, and 'electrostriction' seems to cause dimensional changes of some foils under ECE. In his paper, the existence of the above phenomena in ECE and their impacts on the ECE parameters as well as neutron dosimetry responses and track shapes in polycarbonate and CR-39 neutron dosimeters under different applied field conditions are demonstrated and discussed. (orig.)

  4. Dispersion analysis with inverse dielectric function modelling.

    Science.gov (United States)

    Mayerhöfer, Thomas G; Ivanovski, Vladimir; Popp, Jürgen

    2016-11-01

    We investigate how dispersion analysis can profit from the use of a Lorentz-type description of the inverse dielectric function. In particular at higher angles of incidence, reflectance spectra using p-polarized light are dominated by bands from modes that have their transition moments perpendicular to the surface. Accordingly, the spectra increasingly resemble inverse dielectric functions. A corresponding description can therefore eliminate the complex dependencies of the dispersion parameters, allow their determination and facilitate a more accurate description of the optical properties of single crystals. PMID:27294550

  5. Polariton spectrum in nonlinear dielectric medium

    CERN Document Server

    Dzedolik, Igor V

    2012-01-01

    We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third order dielectric susceptibility at intensity field in the medium. The modulation instability of new branch waves leading to appearance of cnoidal waves and solitons.

  6. Polariton waves in nonlinear dielectric medium

    CERN Document Server

    Dzedolik, I V

    2012-01-01

    The phonon-polariton spectrum in dielectric medium with the third order nonlinearity was theoretically obtained. Dependence of number of polariton spectrum branches on intensity of electromagnetic field was investigated. The appearance of new branches located in the polariton spectrum gap was caused by the influence of dispersion of the third order dielectric susceptibility at increment of the field intensity in the medium. The soliton and cnoidal wave solutions for the polariton excitations for these new spectrum branches were obtained. The all-optical logic gates OR and NOT are proposed as an example of the theory application.

  7. Polariton spectrum in nonlinear dielectric medium.

    Science.gov (United States)

    Dzedolik, Igor V; Karakchieva, Olga

    2013-05-01

    We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third-order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third-order dielectric susceptibility at the intensive electromagnetic field in the medium. The modulation instability of new spectrum branch waves leads to the appearance of the cnoidal waves or solitons. These new nonlinear waves one can use for designing optical devices such as the nonlinear optical filter converter. PMID:23669776

  8. Wave excitation in inhomogeneous dielectric media.

    Science.gov (United States)

    Cary, John R; Xiang, Nong

    2007-11-01

    The equation describing the propagation of a mode driven by external currents in an inhomogeneous dielectric is derived from the principle of the conservation of wave energy density and wave momentum density. The wave amplitude in steady state is obtained in terms of a simple spatial integration of the driving current. The contribution from the spatial derivative of the dielectric response is found to be important. The analytical predictions are verified through comparison with deltaf particle-in-cell computations of electron Bernstein wave propagation, thus showing applicability to kinetic systems. PMID:18233709

  9. Development of dielectric barrier discharging power supply

    Science.gov (United States)

    Gao, Yinghui; Liu, Kun; Fu, Rongyao; Sun, Yaohong; Yan, Ping

    2015-11-01

    Due to the demand of a dielectric barrier discharge power supply, a high voltage and high frequency AC power supply was designed and implemented. Its output voltage is standard or approximate standard sine waveform with the frequency range of 1 kHz to 50 kHz. The output voltage and output frequency can be adjusted individually. The maximum output power of the power supply is 2 kW. It can be operated through local or remote control. The power supply has been used in the dielectric barrier discharging research under different conditions.

  10. Dielectric Engineered Tunnel Field-Effect Transistor

    OpenAIRE

    Ilatikhameneh, Hesameddin; Tarek A. Ameen; Klimeck, Gerhard; Appenzeller, Joerg; Rahman, Rajib

    2015-01-01

    The dielectric engineered tunnel field-effect transistor (DE-TFET) as a high performance steep transistor is proposed. In this device, a combination of high-k and low-k dielectrics results in a high electric field at the tunnel junction. As a result a record ON-current of about 1000 uA/um and a subthreshold swing (SS) below 20mV/dec are predicted for WTe2 DE-TFET. The proposed TFET works based on a homojunction channel and electrically doped contacts both of which are immune to interface stat...

  11. Optical dielectric function of intrinsic amorphous silicon

    International Nuclear Information System (INIS)

    The imaginary part of the optical dielectric function epsilon2(ω) has been calculated using a continuous-random-tetrahedral network as the structural model for the atomic positions. Here the electronic energies and wave functions are determined by first-principles calculations with the method of linear combinations of atomic orbitals (LCAO), and the momentum matrix elements are evaluated directly from the LCAO wave functions. The calculated dielectric function is in good overall agreement with experiment. At energies within 1 eV above the threshold, the epsilon2 curve shows some structures that are due to interband transitions between the localized states near the band gap

  12. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on tunable functionalized copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede;

    2015-01-01

    High driving voltages currently limit the commercial potential of dielectric elastomers (DEs). One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permittivity was prepared through the synthesis of...... phase. Thus, the space between the functional groups can be varied, by using different dimethylsiloxane spacer units between the dipolar molecules. Furthermore, the degree of functionalization can be varied accurately by changing the feed of dipolar molecules. As a result, a completely tunable elastomer...

  13. Stability study of polyacrylic acid films plasma-polymerized on polypropylene substrates at medium pressure

    International Nuclear Information System (INIS)

    Plasma polymerization of acrylic acid has become an interesting research subject, since these coatings are expected to be beneficial for biomedical applications due to their high surface density of carboxylic acid functional groups. However, the application of these monomers is counteracted by their low stability in humid environments, since a high stability is a required characteristic for almost any biological application. The present work investigates whether it is possible to obtain stable deposits with a high retention of carboxylic acid functions by performing plasma polymerization on polypropylene substrates with a dielectric barrier discharge operating at medium pressure. In order to obtain coatings with the desired properties, the plasma parameters need to be optimized. Therefore, in this paper, the influence of discharge power and location of the substrate in the discharge chamber is examined in detail. The properties of the deposited films are studied using contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy. Moreover, to determine whether the obtained deposits are soluble in water, the coatings are once again analyzed after rinsing in water. This paper will clearly show that stable COOH-rich surfaces can be obtained at high discharge power and close to the monomer inlet, which might open perspectives for future biomedical applications.

  14. The use of DBD plasma treatment and polymerization for the enhancement of biomedical UHMWPE

    International Nuclear Information System (INIS)

    Surface modification of polymers for biomedical applications is a thoroughly studied area. The goal of this paper is to show the use of atmospheric pressure plasma technology for the treatment of polyethylene shoulder implants. Atmospheric pressure plasma polymerization of methyl methacrylate will be performed on PE samples to increase the adhesion between the polymer and a PMMA bone cement. For the plasma polymerization, a dielectric barrier discharge is used, operating in a helium atmosphere at an ambient pressure. Parameters such as treatment time, monomer gas flow and discharge power are varied one at a time. Chemical and physical changes at the sample surface are studied making use of X-ray photoelectron spectroscopy and atomic force microscopy measurements. Coating thicknesses are determined by making use of optical reflectance spectroscopy. After characterization, the coated samples are incubated into a phosphate buffered saline solution for a minimum of one week at 37 °C, testing the coating stability when exposed to implant conditions. The results show that PMMA coatings can be deposited with a high degree of control in terms of chemical composition and layer thickness. - Highlights: • Medium pressure DBD successfully activates UHMWPE substrates. • Deposition of PMMA like film via atmospheric pressure DBD on activated UHMWPE • Fast deposition rate is confirmed via optical reflectance spectroscopy. • Relative stable coating found after tests in PBS solution and analysed via FT-IR

  15. Characterization of plasmas and plasma treated polymeric material surfaces for adhesion improvement

    Energy Technology Data Exchange (ETDEWEB)

    Kusano, Y.; Teodoru, S.; Leipold, F.; Michelsen, P.K. (Technical Univ. of Denmark, Optics and Plasma Research Dept., Roskilde (Denmark)); Rozlosnik, N. (Risoe DTU, Materials Research Dept., Roskilde (Denmark)); Soerensen, B.F.; Andersen, T.L.; Goutianos, S. (Technical Univ. of Denmark, Dept. of Micro- and Nanotechnology, Roskilde (Denmark))

    2008-10-15

    Polymeric materials are widely used in a variety of applications, but adhesion to these materials is often difficult because of their low surface energy and poor chemical reactivity. Therefore improving the adhesion to polymeric materials is of considerable importance in assembly of mechanical structures and composite materials. Plasma treatment, which can be operated at room temperature, is attractive for this purpose because they avoid the use of solvents and toxic chemicals, and only the surface is efficiently treated while the bulk properties remain unchanged. With the aim of adhesion improvement, glassy carbon plates, carbon fibres and glass fibre reinforced polyester (GFRP) plates were treated using atmospheric pressure plasmas chosen from a dielectric barrier discharge (DBD) and gliding arcs. Optical emission spectroscopy (OES) of the plasma indicates that oxygen or nitrogen containing radicals were generated, suggesting that they could react at the exposed surfaces during the treatment. Surface characterization using contact angle measurement and x-ray photoelectron spectroscopy (XPS) indicates that after plasma treatment the polar component of surface energy increased and oxygen-containing polar functional groups were effectively introduced onto the surfaces. Raman spectroscopic observation of glassy carbon plates suggests that the defect density, hardness, and density at the surfaces increased with the treatment. Atomic force microscopy indicates that surface roughness tends to increase after the treatment. These characterizations were used for understanding of surface modification effect for observed adhesion improvement. (au)

  16. The use of DBD plasma treatment and polymerization for the enhancement of biomedical UHMWPE

    Energy Technology Data Exchange (ETDEWEB)

    Cools, Pieter, E-mail: Pieter.cools@ugent.be; Van Vrekhem, Stijn; De Geyter, Nathalie; Morent, Rino

    2014-12-01

    Surface modification of polymers for biomedical applications is a thoroughly studied area. The goal of this paper is to show the use of atmospheric pressure plasma technology for the treatment of polyethylene shoulder implants. Atmospheric pressure plasma polymerization of methyl methacrylate will be performed on PE samples to increase the adhesion between the polymer and a PMMA bone cement. For the plasma polymerization, a dielectric barrier discharge is used, operating in a helium atmosphere at an ambient pressure. Parameters such as treatment time, monomer gas flow and discharge power are varied one at a time. Chemical and physical changes at the sample surface are studied making use of X-ray photoelectron spectroscopy and atomic force microscopy measurements. Coating thicknesses are determined by making use of optical reflectance spectroscopy. After characterization, the coated samples are incubated into a phosphate buffered saline solution for a minimum of one week at 37 °C, testing the coating stability when exposed to implant conditions. The results show that PMMA coatings can be deposited with a high degree of control in terms of chemical composition and layer thickness. - Highlights: • Medium pressure DBD successfully activates UHMWPE substrates. • Deposition of PMMA like film via atmospheric pressure DBD on activated UHMWPE • Fast deposition rate is confirmed via optical reflectance spectroscopy. • Relative stable coating found after tests in PBS solution and analysed via FT-IR.

  17. The influence of a polymeric adhesion layer on gate insulators in organic thin-film-transistors

    International Nuclear Information System (INIS)

    The electrical characteristics of organic thin-film-transistors (OTFTs) can be improved by inserting an adhesion layer on the gate dielectric prior to the deposition of the organic semiconductor. A polyimide (PI) film was used as polymeric adhesion layer deposited on an inorganic gate insulator such as silicon dioxide (SiO2) or silicon nitride (SiNx), and the adhesion layer was formed by using a vapor deposition polymerization (VDP), instead of a spin-coating process. The molecular ordering of pentacene could be enhanced by using a PI adhesion layer which has a lower surface energy and roughness than SiO2 or SiNx. We also investigated the electrical characteristics of OTFTs for different thickness of the PI adhesion layer. The OTFTs with an adhesion layer attained on on/off ratio of ∼ 106, a threshold voltage of -0.8 ∼ 4 V, and a subthreshold slope of 2.0 ∼ 2.5 V/decade. Especially, a field effect mobility, of about 0.01 cm2/Vs was obtained for bare SiO2 and SiNx, whereas with an adhesion layer, as improved value of 0.1 ∼ 0.4 cm2/Vs was obtained, which depended on the thickness of the PI layer.

  18. A Review on Conduction Mechanisms in Dielectric Films

    OpenAIRE

    Fu-Chien Chiu

    2014-01-01

    The conduction mechanisms in dielectric films are crucial to the successful applications of dielectric materials. There are two types of conduction mechanisms in dielectric films, that is, electrode-limited conduction mechanism and bulk-limited conduction mechanism. The electrode-limited conduction mechanism depends on the electrical properties at the electrode-dielectric interface. Based on this type of conduction mechanism, the physical properties of the barrier height at the electrode-diel...

  19. Performance of Polymer Modified Mortar with Different Dosage of Polymeric Modifier

    OpenAIRE

    Ganesan Shankar; Othuman Mydin Md Azree; Sani Norazmawati Md.; Che Ani Adi Irfan

    2014-01-01

    Polymer modified mortar system is defined as hydraulic cement combined at the time of mixing with organic polymers that are dispersed or re-dispersed in water, with or without aggregates. The compressive strength and flexural strength of polymer modified mortar obtained at early age are low and it required prolong curing period for the strength enhancement. In order to enhance the mechanical properties of cementitious mixture as well as its durability, hybridization of polymeric modifiers are...

  20. Comparison of an elemental and polymeric enteral diet in patients with normal gastrointestinal function.

    OpenAIRE

    Jones, B. J.; Lees, R; Andrews, J; Frost, P.; Silk, D. B.

    1983-01-01

    In a prospective controlled clinical trial, 70 patients with normal gastrointestinal function were randomised to receive either an elemental diet based on Vivonex HN or an isonitrogenous isocalorie polymeric diet based on Clinifeed 400, administered by continuous 24 hour nasogastric infusion. The two groups of patients were well matched for age, sex, diagnosis, prior starvation, duration of feeding, initial nutritional status, and metabolic status. Nitrogen losses were significantly less on t...

  1. Photoelectric metal, dielectric, semiconductor (MDP) instruments. Fotoelektricheskiye MDP-pribory

    Energy Technology Data Exchange (ETDEWEB)

    Zuyev, V.A.; Popov, V.G.

    1983-01-01

    The basic patterns in photoelectrical phenomena in metal dielectric semiconductor structures are examined. The promise is noted for the use of metal dielectric semiconductor structures as the elementary base for electrooptics and as solar energy converters. The physical bases are presented of different metal dielectric semiconductor photoconverters: photoresistors, photodiodes and photoelements, photovaricaps, phototransistors and systems for recording optical information.

  2. Functionalized polymer networks: synthesis of microporous polymers by frontal polymerization

    Indian Academy of Sciences (India)

    N S Pujari; A R Vishwakarma; T S Pathak; A M Kotha; S Ponrathnam

    2004-12-01

    A series of glycidyl methacrylate (GMA)–ethylene dimethacrylate (EGDM) copolymers of varying compositions were synthesized by free-radically triggered thermal frontal polymerization (FP) as well as by suspension polymerization (SP) using azobisisobutyronitrile [AIBN] as initiator. The two sets of copolymers were characterized by IR spectroscopy and mercury intrusion porosimetry, for determination of epoxy number and specific surface area. Frontal polymerization was more efficient, yielding greater conversions at much shorter reaction times. The self-propagating frontal polymerization also generates microporous material with narrow pore size distribution. It yields higher internal pore volume and surface area than suspension polymerization, surface morphologies are, however, inferior.

  3. Kinetics of aniline polymerization initiated with iron(III) chloride

    OpenAIRE

    KATARINA B. JEREMIC; SLOBODAN M. JOVANOVIC

    2006-01-01

    The reaction kinetics of the chemical polymerization of aniline in aqueous acid solutions with FeCl3 as the oxidant (initiator) was investigated at 25 oC. The polymerization was performed in a special reactor which enabled the initial concentration of oxidant to be kept constant during the polymerization reaction. The order of the reaction of ANI polymerization with respect to FeCl3 was calculated as n = 0.18. The rate constant k of the polymerization reaction was found to be 9.1x10-5 (mol dm...

  4. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  5. Coupling of phonon-polariton modes at dielectric-dielectric interfaces by the ATR technique

    Science.gov (United States)

    Cocoletzi, G. H.; Olvera Hernández, J.; Martínez Montes, G.

    1989-08-01

    We report the calculated ATR dispersion relation of the interface phonon-polariton modes in the prism-dielectric-dielectric configuration. Comparison of electromagnetic dispersion relations (EMDR) with the ATR dispersion relations are presented for three different interfaces: I) GaAs/GaP, II) CdF2/CaF2 and III) CaF2/GaP in two propagation windows, using the Otto and Kretschmann geometries for p-polarized light. We have studied the three cases using angle and frequency scans for each window and geometry. The results indicate that it is possible to excite and detect phonon-polariton modes at the dielectric-dielectric interface.

  6. All-dielectric left-handed metamaterial based on dielectric resonator: design, simulation and experiment

    International Nuclear Information System (INIS)

    Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative permittivity and negative permeability, so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial. Based on this principle, this paper studies the field distribution in high-permittivity dielectric materials. The field distributions at different resonant modes are analysed based on the dielectric resonator theory. The origination and influence factors of the electric and magnetic dipoles are confirmed. Numerical simulations indicate that by combining dielectric cubes with different sizes, the electric resonance frequency and magnetic resonance frequency can be superposed. Finally, experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  7. Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren;

    2015-01-01

    permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs is...... demonstrated herein, and a number of many and important parameters, such as dielectric permittivity/loss, viscoelastic properties and dielectric breakdown strength, are investigated. Ionic and silicone elastomer IPNs are promising prospects for dielectric elastomer actuators, since very high permittivities are...... obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity as...

  8. A self-similarity model for dielectric constant of porous ultra low-k dielectrics

    International Nuclear Information System (INIS)

    A self-similarity model applying the Sierpinski carpet approximation for the effective dielectric constant of nanoporous low-k dielectrics is proposed based on the statistically self-similar characteristics of pore size distributions in the medium and on the 'mixture rule' technique. The proposed model for the dielectric constant is expressed as a function of porosity (related to stage n of Sierpinski carpet) and the dielectric coefficient of components of the medium. The model predictions are compared with the existing experimental data and with other model predictions, and good agreement is obtained between the present model predictions and the experimental data. The proposed technique may have the potential of analysing other properties such as thermal conductivity and Young's modulus

  9. All-dielectric left-handed metamaterial based on dielectric resonator: design, simulation and experiment

    Institute of Scientific and Technical Information of China (English)

    Yang Yi-Ming; Wang Jia-Fu; Xia Song; Bai Peng; Li Zhe; Wang Jun; Xu Zhuo; Qu Shao-Bo

    2011-01-01

    Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative permittivity and negative permeability, so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial. Based on this principle, this paper studies the field distribution in high-permittivity dielectric materials. The field distributions at different resonant modes are analysed based on the dielectric resonator theory. The origination and influence factors of the electric and magnetic dipoles are confirmed. Numerical simulations indicate that by combining dielectric cubes with different sizes, the electric resonance frequency and magnetic resonance frequency can be superposed. Finally, experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means.

  10. Evaluation of cable ageing in Nuclear Power Plants

    International Nuclear Information System (INIS)

    The majority of power, control and instrumentation cables in nuclear power plants use polymers as their basic material for insulation and jacket. In many cases, these cables form part of safety-related circuits and should therefore be capable of operating correctly under both normal and accident conditions. Since polymeric materials are degraded by the long term action of the radiation and thermal environments found in the plant, it is important to be able to establish the cable condition during the plant lifetime. Nowadays there are a number of different methods to evaluate the remaining lifetime of cables. In the case of new plants, or new cables in old plants, accelerated ageing tests and predictive models can be used to establish the behaviour of the cable materials under operating conditions. There are verified techniques and considerable experience in the definition of predictive models. This type of approach is best carried out during the commissioning stage or in the early stages of operation. In older plants, particularly where there is a wide range of cable types in use, it is more appropriate to use condition monitoring methods to establish the state of degradation of cables in-plant. Over the last 10 years there have been considerable developments in methods for condition monitoring of cables and a tool-box of practical techniques are now available. There is no single technique which is suitable for all cable materials but the range of methods covers nearly all of the types currently in use, at present, the most established methods are the indented, thermal analysis (OIT, OITP and TGA) and dielectric loss measurements, All of these are either non-destructive methods or require only micro-samples of material. (Author) 15 refs

  11. Development of dielectric window to conductor assembly

    Energy Technology Data Exchange (ETDEWEB)

    Heikinheimo, L.; Nuutinen, S.; Taehtinen, S. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity

    1998-12-31

    The report summarises the work done by Association Euratom-Tekes in developing manufacturing procedures for vacuum tight ceramic to metal joints and in manufacturing full scale components for the ICRF vacuum window construction. The development started at VTT Manufacturing Technology in 1996 under the Task T238.2 and continued in 1997 under the Underlying Technology tasks. In the design of the components, the following issues were addressed and resolved: (1) The choice of dielectric material; The choice is made as the best compromise among nuclear, mechanical, and thermal properties, but in due consideration of material availability, fabrication issues and response to cyclic loads, (2) Layout and detailed design. The shape of the dielectric window is optimized to minimize electric fields in the dielectric materials; The optimised field distribution is computed in a 2D geometry; The design includes thermal calculation and the cooling layout and includes provision for remote handling replacement in one block, (3) Metal/dielectric joining. The joining technology is selected and justified. Joining tests on material selections to verify the applicability has been done, the validation of the design pre-prototype tests have been carried out selectively. The steps for the manufacture of these full scale components are described in the report with the appropriate concluding remarks and suggestions for the further actions. (orig.)

  12. DIELECTRIC RESEARCH OF POLYISOPRENE MODIFIED BY CARBAMIDE

    OpenAIRE

    Острогруд, А.Ю.

    2012-01-01

    Conducted dielectric research of polyisoprene modification by polyacrylamide in the frequency range 1-100 kHz have shown the existence of increase or decrease in molecular mobility groups of atoms and cross-site segments of the mesh polyisoprene through the displacement of existing relaxation processes in the direction of high or low frequencies at various contents of polyacrylamide.

  13. Nonlinear polariton waves in dielectric medium

    CERN Document Server

    Dzedolik, Igor V

    2012-01-01

    We theoretically investigate the properties of phonon-polariton inhomogeneous harmonic wave, cnoidal wave and spatial soliton propagating in boundless dielectric medium and compute the shape of nonlinear vector polariton wave. We obtain analytically the envelopes of linearly polarized nonlinear polariton waves in the self-focusing and self-defocusing media.

  14. Bandwidth Enhancement Techniques of Dielectric Resonator Antenna

    Directory of Open Access Journals (Sweden)

    ARCHANA SHARMA

    2011-07-01

    Full Text Available The paper briefly reviews the historical background of dielectric resonator antenna and its bandwidth enhancement techniques. The main focus is on a compact DRA that can offer broad band operation. It has been illustrated that dual resonance and multi resonance operation can be much effective to give wide band characteristics of DRA.

  15. Dielectric anomaly in coupled rotor systems

    OpenAIRE

    Shima, Hiroyuki; Nakayama, Tsuneyoshi

    2004-01-01

    The correlated dynamics of coupled quantum rotors carrying electric dipole moment is theoretically investigated. The energy spectra of coupled rotors as a function of dipolar interaction energy is analytically solved. The calculated dielectric susceptibilities of the system show the peculiar temperature dependence different from that of isolated rotors.

  16. Dielectric anomaly in coupled rotor systems

    OpenAIRE

    Shima, Hiroyuki; Nakayama, Tsuneyoshi

    2004-01-01

    The correlated dynamics of coupled quantum rotors carrying electric dipole moment is theoretically investigated. The energy spectra of coupled rotors as a function of dipolar interaction energy are analytically solved. The calculated dielectric susceptibilities of the system show a peculiar temperature dependence different from that of isolated rotors.

  17. DIELECTRIC WAKE FIELD RESONATOR ACCELERATOR MODULE

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L.

    2013-11-06

    Results are presented from experiments, and numerical analysis of wake fields set up by electron bunches passing through a cylindrical or rectangular dielectric-lined structure. These bunches excite many TM-modes, with Ez components of the wake fields sharply localized on the axis of the structure periodically behind the bunches. The experiment with the cylindrical structure, carried out at ATF Brookhaven National Laboratory, used up to three 50 MeV bunches spaced by one wake field period (21 cm) to study the superposition of wake fields by measuring the energy loss of each bunch after it passed through the 53-cm long dielectric element. The millimeter-wave spectrum of radiation excited by the passage of bunches is also studied. Numerical analysis was aimed not only to simulate the behavior of our device, but in general to predict dielectric wake field accelerator performance. It is shown that one needs to match the radius of the cylindrical dielectric channel with the bunch longitudinal rms-length to achieve optimal performance.

  18. Near-field compact dielectric optics

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M.; Ng, Tuck Wah

    2006-08-01

    Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle.

  19. Dielectric Properties of Water Under Extreme Conditions

    Science.gov (United States)

    Pan, Ding

    2014-03-01

    Water is a major component of fluids in the Earth's mantle, where its properties are substantially different from those at ambient conditions. At the pressures and temperatures of the mantle, experiments on aqueous fluids are challenging, and several fundamental properties of water are poorly known; e.g., its dielectric constant has not been measured. This lack of knowledge of water dielectric properties has greatly limited our ability to model water-rock interactions and, in general, our understanding of aqueous fluids below the Earth's crust. Using ab initio molecular dynamics, we computed the dielectric constant of water under the conditions of the Earth's upper mantle, and we predicted the solubility products of carbonate minerals. We found that MgCO3 (magnesite)--insoluble in water under ambient conditions--becomes at least slightly soluble at the bottom of the upper mantle, suggesting that water may transport significant quantities of oxidized carbon. We also computed the electronic dielectric constant of water as a function of pressure and we found that, contrary to expectations based on widely used simple models, both the refractive index and the electronic band gap of water increase under pressure. The work is supported by DOE-CMCSN under Grant DE-SC0005180 and by the Sloan Foundation through the Deep Carbon Observatory.

  20. Partial discharges and bulk dielectric field enhancement

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Johansson, Torben

    A consequence of partial discharge activity within a gaseous void is the production of a field enhancement in the solid dielectric in the proximity of the void. This situation arises due to the charge created by the partial discharges accumulating at the void wall. The influence of the spatial...

  1. Actuation response of polyacrylate dielectric elastomers

    DEFF Research Database (Denmark)

    Kofod, G.; Kornbluh, R.; Pelrine, R.;

    2001-01-01

    Polyacrylate dielectric elastomers have yielded extremely large strain and elastic energy density suggesting that they are useful for many actuator applications. A thorough understanding of the physics underlying the mechanism of the observed response to an electric field can help develop improved...

  2. Dielectric Elastomer Based "Grippers" for Soft Robotics.

    Science.gov (United States)

    Shian, Samuel; Bertoldi, Katia; Clarke, David R

    2015-11-18

    The use of few stiff fibers to control the deformation of dielectric elastomer actuators, in particular to break the symmetry of equi-biaxial lateral strain in the absence of prestretch, is demonstrated. Actuators with patterned fibers are shown to evolve into unique shapes upon electrical actuation, enabling novel designs of gripping actuators for soft robotics. PMID:26418227

  3. Casimir effect in dielectrics: Bulk energy contribution

    International Nuclear Information System (INIS)

    In a recent series of papers, Schwinger discussed a process that he called the dynamical Casimir effect. The key essence of this effect is the change in zero-point energy associated with any change in a dielectric medium. (In particular, if the change in the dielectric medium is taken to be the growth or collapse of a bubble, this effect may have relevance to sonoluminescence.) The kernel of Schwinger close-quote s result is that the change in Casimir energy is proportional to the change in the volume of the dielectric, plus finite-volume corrections. Other papers have called into question this result, claiming that the volume term should actually be discarded, and that the dominant term remaining is proportional to the surface area of the dielectric. In this paper, which is an expansion of an earlier Letter on the same topic, we present a careful and critical review of the relevant analyses. We find that the Casimir energy, defined as the change in zero-point energy due to a change in the medium, has at leading order a bulk volume dependence. This is in full agreement with Schwinger close-quote s result, once the correct physical question is asked. We have nothing new to say about sonoluminescence itself. copyright 1997 The American Physical Society

  4. Open-access dielectric elastomer material database

    Science.gov (United States)

    Vertechy, R.; Fontana, M.; Stiubianu, G.; Cazacu, M.

    2014-03-01

    Dielectric Elastomer Transducers (DETs) are deformable capacitors that can be used as sensors, actuators and generators. The design of effective and optimized DETs requires the knowledge of a set of relevant properties of the employed Dielectric Elastomer (DE) material, which make it possible to accurately predict their electromechanical dynamic behavior. In this context, an open-access database for DE materials has been created with the aim of providing the practicing engineer with the essential information for the design and optimization of new kinds of DET. Among the electrical properties, dielectric susceptibility, dielectric strength and conductivity are considered along with their dependence on mechanical strain. As regards mechanical behavior, experimental stress-strain curves are provided to predict hyperelasticity, plasticity, viscosity, Mullins effect and mechanical rupture. Properties of commercial elastomeric membranes have been entered in the database and made available to the research community. This paper describes the instrumentations, experimental setups and procedures that have been employed for the characterization of the considered DE materials. To provide an example, the experimental data acquired for a commercially available natural rubber membrane (OPPO Band Red 8012) are presented.

  5. Dielectric tensor of strongly coupled plasmas

    International Nuclear Information System (INIS)

    Complex conductivity and dielectric permeability tensors of strongly coupled plasmas are studied and constructed on the basis of exact relations and sum rules. Both Coulomb and magnetic correlation are taken into account. The electromagnetic mode dispersion law is studied. The magnetostatic properties of a system of charged particles are investigated in detail. 26 refs

  6. 7th International Symposium on Gaseous Dielectrics

    CERN Document Server

    James, David

    1994-01-01

    The Seventh International Symposium on Gaseous Dielectrics was held in Knoxville, Tennessee, U. S. A. , on April 24-28, 1994. The symposium continued the interdisciplinary character and comprehensive approach of the preceding six symposia. Gaseous DielecIries VII is a detailed record of the symposium proceedings. It covers recent advances and developments in a wide range of basic, applied and industrial areas of gaseous dielectrics. It is hoped that Gaseous DielecIries VII will aid future research and development in, and encourage wider industrial use of, gaseous dielectrics. The Organizing Committee of the Seventh International Symposium on Gaseous Dielectrics consisted of G. Addis (U. S. A. ), L. G. Christophorou (U. S. A. ), F. Y. Chu (Canada), A. H. Cookson (U. S. A. ), O. Farish (U. K. ), I. Gallimberti (Italy) , A. Garscadden (U. S. A. ), D. R. James (U. S. A. ), E. Marode (France), T. Nitta (Japan), W. Pfeiffer (Germany), Y. Qiu (China), I. Sauers (U. S. A. ), R. J. Van Brunt (U. S. A. ), and W. Zaengl...

  7. Casimir effect in dielectrics Bulk Energy Contribution

    CERN Document Server

    Carlson, C E; Pérez-Mercader, J; Visser, M; Visser, Matt

    1997-01-01

    In a recent series of papers, Schwinger discussed a process that he called the Dynamical Casimir Effect. The key essence of this effect is the change in zero-point energy associated with any change in a dielectric medium. (In particular, if the change in the dielectric medium is taken to be the growth or collapse of a bubble, this effect may have relevance to sonoluminescence.) The kernel of Schwinger's result is that the change in Casimir energy is proportional to the change in volume of the dielectric, plus finite-volume corrections. Other papers have called into question this result, claiming that the volume term should actually be discarded, and that the dominant term remaining is proportional to the surface area of the dielectric. In this communication, which is an expansion of an earlier letter on the same topic, we present a careful and critical review of the relevant analyses. We find that the Casimir energy, defined as the change in zero-point energy due to a change in the medium, has at leading orde...

  8. The Electrical Breakdown of Thin Dielectric Elastomers

    DEFF Research Database (Denmark)

    Zakaria, Shamsul Bin; Morshuis, Peter H. F.; Yahia, Benslimane Mohamed;

    2014-01-01

    Dielectric elastomers are being developed for use in actuators, sensors and generators to be used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. In order to obtain maximum efficiency, the devices are operated at high electrical fields...

  9. Dielectric Signatures of Annealing in Glacier Ice

    Science.gov (United States)

    Grimm, R. E.; Stillman, D. E.; MacGregor, J. A.

    2015-12-01

    We analyzed the dielectric spectra of 49 firn and ice samples from ice sheets and glaciers to better understand how differing ice formation and evolution affect electrical properties. The dielectric relaxation of ice is well known and its characteristic frequency increases with the concentration of soluble impurities in the ice lattice. We found that meteoric ice and firn generally possess two such relaxations, indicating distinct crystal populations or zonation. Typically, one population is consistent with that of relatively pure ice, and the other is significantly more impure. However, high temperatures (e.g., temperate ice), long residence times (e.g., ancient ice from Mullins Glacier, Antarctica), or anomalously high impurity concentrations favor the development of a single relaxation. These relationships suggest that annealing causes two dielectrically distinct populations to merge into one population. The dielectric response of temperate ice samples indicates increasing purity with increasing depth, suggesting final rejection of impurities from the lattice. Separately, subglacially frozen samples from the Vostok 5G ice core possess a single relaxation whose variable characteristic frequency likely reflects the composition of the source water. Multi-frequency electrical measurements on cores and in the field can track annealing of glacier ice.

  10. Optimization of Organotin Polymers for Dielectric Applications.

    Science.gov (United States)

    Treich, Gregory M; Nasreen, Shamima; Mannodi Kanakkithodi, Arun; Ma, Rui; Tefferi, Mattewos; Flynn, James; Cao, Yang; Ramprasad, Rampi; Sotzing, Gregory A

    2016-08-24

    Recently, there has been a growing interest in developing wide band gap dielectric materials as the next generation insulators for capacitors, photovoltaic devices, and transistors. Organotin polyesters have shown promise as high dielectric constant, low loss, and high band gap materials. Guided by first-principles calculations from density functional theory (DFT), in line with the emerging codesign concept, the polymer poly(dimethyltin 3,3-dimethylglutarate), p(DMTDMG), was identified as a promising candidate for dielectric applications. Blends and copolymers of poly(dimethyltin suberate), p(DMTSub), and p(DMTDMG) were compared using increasing amounts of p(DMTSub) from 10% to 50% to find a balance between electronic properties and film morphology. DFT calculations were used to gain further insight into the structural and electronic differences between p(DMTSub) and p(DMTDMG). Both blend and copolymer systems showed improved results over the homopolymers with the films having dielectric constants of 6.8 and 6.7 at 10 kHz with losses of 1% and 2% for the blend and copolymer systems, respectively. The energy density of the film measured as a D-E hysteresis loop was 6 J/cc for the copolymer, showing an improvement compared to 4 J/cc for the blend. This improvement is hypothesized to come from a more uniform distribution of diacid repeat units in the copolymer compared to the blend, leading toward improved film quality and subsequently higher energy density. PMID:27467895

  11. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  12. Large scale processing of dielectric electroactive polymers

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu

    Efficient processing techniques are vital to the success of any manufacturing industry. The processing techniques determine the quality of the products and thus to a large extent the performance and reliability of the products that are manufactured. The dielectric electroactive polymer (DEAP...

  13. Chains of coupled square dielectric optical microcavities

    NARCIS (Netherlands)

    Hammer, Manfred

    2009-01-01

    Chains of coupled square dielectric cavities are investigated in a 2-D setting, by means of a quasi-analytical eigenmode expansion method. Resonant transfer of optical power can be achieved along quite arbitrary, moderately long rectangular paths (up to 9 coupled cavities are considered), even with

  14. Photon Momentum in Linear Dielectric Media

    CERN Document Server

    Crenshaw, Michael E

    2015-01-01

    According to the scientific literature, the momentum of a photon in a simple linear dielectric is either $\\hbar\\omega/(nc)$ or $n\\hbar\\omega/c$ with a unit vector ${\\bf \\hat e}_k$ in the direction of propagation. These momentums are typically used to argue the century-old Abraham--Minkowski controversy in which the momentum density of the electromagnetic field in a dielectric is either the Abraham momentum density, ${\\bf g}_A={\\bf E}\\times{\\bf H}/c$, or the Minkowski momentum density, ${\\bf g}_M={\\bf D}\\times{\\bf B}/c$. The elementary optical excitations, photons, are typically known as polaritions in the particular case of light traveling in a dielectric medium. Applying the relativistic energy formula, we find that the total momentum that is attributable to a polariton in a dielectric is $\\hbar\\omega{\\bf \\hat e}_k/c$ corresponding to a total momentum density ${\\bf g}_T=n{\\bf E}\\times{\\bf B}/c$.

  15. Vectorial analysis of dielectric photonic crystal VCSEL

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    A new vertical-cavity surface-emitting laser structure employing a dielectric photonic crystal mirror has been suggested and been numerically investigated. The new structure has a smaller threshold gain, a moderate strength of single-transverse-mode operation, a high quality of emission beam free...

  16. Spontaneous emission from active dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Tromborg, Bjarne

    2001-01-01

    engineered due to the dependence of the emission rate on the location and polarisation of the emitters in the structure. This paper addresses the methods of quantum electrodynamics of dielectric media which enable calculation of the local rate of spontaneous emission in active microstructures....

  17. Characterization of Dielectric Electroactive Polymer transducers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Møller, Martin B.; Sarban, Rahimullah;

    2014-01-01

    This paper analysis the small-signal model of the Dielectric Electro Active Polymer (DEAP) transducer. The DEAP transducer have been proposed as an alternative to the electrodynamic transducer in sound reproduction systems. In order to understand how the DEAP transducer works, and provide...

  18. Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and radical polymerization

    Indian Academy of Sciences (India)

    Dhruba Jyoti Haloi; Bishnu Prasad Koiry; Prithwiraj Mandal; Nikhil Kumar Singha

    2013-07-01

    This investigation reports a comparative study of poly(2-ethylhexyl acrylate) (PEHA) prepared via atom transfer radical polymerization (ATRP), reverse atom transfer radical polymerization (RATRP) and conventional free radical polymerization (FRP). The molecular weights and the molecular weight distributions of the polymers were measured by gel permeation chromatography (GPC) analysis. Structural characterization of the polymers was carried out by 1H NMR and MALDI-TOF-MS analyses. Thermal properties of the polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymerization results and the thermal properties of PEHAs prepared via ATRP, RATRP and FRP were compared.

  19. Electrical insulating materials - Determination of the effects of ionizing radiation - Part 5: Procedures for assessment of ageing in service

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2003-01-01

    Covers ageing assessment methods which can be applied to components based on polymeric materials (for example, cable insulation and jackets, elastomeric seals, polymeric coatings, gaiters) which are used in environments where they are exposed to radiation. The object of this part of IEC 60544 is to provide guidelines on the assessment of ageing in service. The approaches discussed cover ageing assessment programmes based on condition monitoring (CM), the use of equipment deposits in severe environments and sampling of real-time aged components.

  20. Radiation-induced polymerization of hydrogen cyanide

    International Nuclear Information System (INIS)

    The chain reaction of HCN polymerization in a γ-radiation field does not occur at 77 K. When irradiated HCN is warmed up to ambient temperature, a polymer is formed. The heat of polymerization of HCN is 44.0±6.0 kJ/mol and the polymer yield reaches 2.5% for a dose of 725 kGy. Amorphous polymer products (with yields increasing up to 33.5%) and needle crystals (presumably HCN tetramer) are formed upon storage of irradiated HCN at room temperature. The polymer is stable below 700 K, has a conductivity of 3x10-5Ω-1cm-f1, and displays an EPR spectrum typical of polyconjugated systems. A radical mechanism of the formation of conjugated chain -C=N-C=N- is suggested. The tetramer is produced by a combination of aminocyanocarbene biradicals

  1. Hyperbranched polymers from polymerization in solid state

    International Nuclear Information System (INIS)

    The macroscopic properties of polymers are directly related to the chemical characteristics of the monomeric units and also with the geometric arrangement of polymer chains. Thus, polymers were synthesized from two well-known chelators EDTA and EDA. We evaluated the conditions for the polymerization of the precursors in the solid state. The polymerization was carried out varying the proportions of reagents, aiming the polymers with different degrees of chain branching and the materials were characterized by FTIR. The materials obtained from the best condition for synthesis were purified by size-exclusion chromatography of and were subjected to characterization by FTIR and NMR of 1H and 13C. The content of end groups in these samples was determined by back titration. (author)

  2. Inflation and Instability of a Polymeric Membrane

    DEFF Research Database (Denmark)

    Hassager, Ole; Kristensen, Susanne Brogaard; Larsen, Johannes Ruben;

    1999-01-01

    We consider an axisymmetric polymeric membrane inflated by a uniform pressure difference acting across the membrane. The polymeric material is described by an arbitrary combination of a viscoelastic and a purely viscous component to the stress. Some viscoelastic materials described by a Mooney......-Rivlin model show a monotone increasing pressure during inflation of a spherical membrane. These materials develop a homogeneous membrane thickness in agreement with the Considere-Pearson condition. Molecularly based models such as the neo-Hookean, Doi-Edwards or Tom-Pom model show a pressure maximum when...... inflated. Membranes described by these models develop a local thinning of the membrane which may lead to bursting in finite time. (C) 1999 Elsevier Science B.V. All rights reserved....

  3. Polymeric Piezoelectric Transducers for Hydrophone Applications

    Directory of Open Access Journals (Sweden)

    D. K. Kharat

    2007-01-01

    Full Text Available Conventional ceramic piezoelectric materials have been used in hydrophones for sonarapplications since 1940's. In the last few years since the discovery of polymeric piezoelectrichydrophones, the technology has matured, applications have emerged in extraordinary number ofcases such as underwater navigation, biomedical applications, biomimetics, etc. Hydrophones areused underwater at high hydrostatic pressures. In the presence of hydrostatic pressures, theanisotropic piezoelectric response of ceramic materials is such that it has poor hydrophone performancecharacteristics whereas polymeric piezoelectric materials show enough hydrostatic piezoelectriccoefficients. Moreover, piezoelectric polymers have low acoustic impedance, which is only 2-6 timethat of water, whereas in piezoelectric ceramics, it is typically 11-time greater than that of water. Aclose impedance match permits efficient transduction of acoustic signals in water and tissues. Newlydeveloped hydrostatic-mode polyvinylidene flouride (PVDF hydrophones use a pressure-releasesystem to achieve improved sensitivity. Recently, voided PVDF materials have been used for makinghydrophones having higher sensitivity and figure of merit than unvoided PVDF materials.

  4. Latent and delayed action polymerization systems.

    Science.gov (United States)

    Naumann, Stefan; Buchmeiser, Michael R

    2014-04-01

    Various approaches to latent polymerization processes are described. In order to highlight recent advances in this field, the discussion is subdivided into chapters dedicated to diverse classes of polymers, namely polyurethanes, polyamides, polyesters, polyacrylates, epoxy resins, and metathesis-derived polymers. The described latent initiating systems encompass metal-containing as well as purely organic compounds that are activated by external triggers such as light, heat, or mechanical force. Special emphasis is put on the different chemical venues that can be taken to achieve true latency, which include masked N-heterocyclic carbenes, latent metathesis catalysts, and photolatent radical initiators, among others. Scientific challenges and the advantageous application of latent polymerization processes are discussed. PMID:24519912

  5. Polymeric membrane studied using slow positron beam

    International Nuclear Information System (INIS)

    A radioisotope slow positron beam has been built at the Chung Yuan Christian University in Taiwan for the research and development in membrane science and technology. Doppler broadening energy spectra and positron annihilation lifetime have been measured as a function of positron energy up to 30 keV in a polyamide membrane prepared by the interfacial polymerization between triethylenetetraamine (TETA) and trimesoyl chloride (TMC) on modified porous polyacrylonitrile (PAN) asymmetric membrane. The multilayer structures and free-volume depth profile for this asymmetric membrane system are obtained. Positron annihilation spectroscopy coupled with a slow beam could provide new information about size selectivity of transporting molecules and guidance for molecular designs in polymeric membranes

  6. Radiation polymerization of tetrafluoroethylene in freon-22

    International Nuclear Information System (INIS)

    The radiation-induced solution-polymerization of tetrafluoroethylene in Freon-22 has been investigated over a temperature range of - 62 degrees celcius to 0 degrees celcius. The rate of polymerization for the in-source process was found to be directly propertional to monomer concentration and an activation energy of only 7,66 kj/mole was calculated. The number-average molecular mass of the product PTFE ranged from 2X104 to 6X104 and was relatively independent of the usual reaction parameters. The rate of postpolymerization was also found to be directly proportional to monomer concentration. The postpolyerization process did not result in any enchancement of the initial PTFE molecular mass

  7. Radiation-induced emulsion polymerization of tetrafluoroethylene

    International Nuclear Information System (INIS)

    The radiation-induced emulsifier-free emulsion polymerization of tetrafluoroethylene (TFE) has been studied at initial pressure 2 - 25 kg/cm2 and temperature 300 - 1100C for dose rate 0.57 x 104 - 3.0 x 104 rad/hr. Polytetrafluoroethylene (PTFE), a hydrophobic polymer, forms as a stable latex in the absence of an emulsifier. Stability of the latex is governed by the dose rate/TFE pressure ratio; it increases with sufficient TFE monomer. PTFE particles produced in this polymerization system are stable due to the carboxyl end groups and adsorption of OH- and HF on the particles. PTFE latex of molecular weight higher than 2 x 107 is obtained by addition of a radical scavenger such as hydroquinone. The molecular weight of PTFE can be measured from the heat of crystallization conveniently with high reliability, which was found in the course of study on the melting and crystallization behavior. (author)

  8. Pharmaceutical Applications of Polymeric Nano materials

    International Nuclear Information System (INIS)

    With significant attention focused on nano science and nano technology in recent years, nano materials have been used in a wide variety of applications such as automotive, environmental, energy, catalysis, biomedical, drug delivery, and polymeric industries. Among those fields, the application of nano materials with pharmaceutical science is an emerging and rapidly growing field and has drawn increasing attention recently. Research and development in this field is mainly focused on several aspects such as the discoveries of novel functional nano materials, exploration on nanoparticles with controlled and targeted drug delivery characteristics, and investigation of bio functionalized and diagnostic nano materials. In this special issue, we have invited a few papers related to recent advances in pharmaceutical application of polymeric nano materials

  9. Polymeric materials for atomic power industry

    International Nuclear Information System (INIS)

    In the atomic power industry such as nuclear power generating stations, organic polymeric materials are widely used. Those materials have superior properties for electric insulation, for the fabricability and flexibility, so they are conveniently used from the viewpoint of economics too. Here, it is important to recognize the limit of their usage. The first chapter deals with the introduction of the polymeric materials for atomic power industry, i.e. their limiting usage under irradiation, and type test of the equipments. The second chapter describes the testing of the flamability of wire and cable which is mostly concerned at present. The third chapter introduces the accident at the Three Mile Island Nuclear Power Generating Station, which accident has given strong shock in the world, and the last chapter tells the fire accident at the Browns Ferry Nuclear Power Generating Station, which accident has accelerated the development of the fire resistant polymers. (author)

  10. A dielectric resonator method of measuring dielectric properties of low loss materials in the microwave region

    Science.gov (United States)

    Sheen, Jyh

    2008-05-01

    A technique for the measurement of dielectric properties of low loss and homogeneously isotropic media in the microwave region is studied. The measuring structure is a resonator made up of a cylindrical dielectric rod and conducting plates. The dielectric constants and loss tangents are computed from the resonant frequencies, structure dimensions and unloaded Qs of the TE01δ mode. A simple field model is introduced to analyze this resonator structure. Unlike other simple models, this model does not have the defect of low measurement accuracy of dielectric properties. Important factors affecting the dielectric properties measurements are introduced. Error sources for measurements are also discussed. The measurement accuracy is justified by comparing the results with those of other techniques. In addition, various methods for calculating the power factor and conducting loss and for measuring the conductivity of the conducting plates are discussed. The accuracies of certain of these methods have not previously been studied, but are given in this paper. The swept frequency capability was also studied. It was found that dielectric properties in microwave frequencies could be measured within a frequency range of 3 GHz.

  11. A dielectric resonator method of measuring dielectric properties of low loss materials in the microwave region

    International Nuclear Information System (INIS)

    A technique for the measurement of dielectric properties of low loss and homogeneously isotropic media in the microwave region is studied. The measuring structure is a resonator made up of a cylindrical dielectric rod and conducting plates. The dielectric constants and loss tangents are computed from the resonant frequencies, structure dimensions and unloaded Qs of the TE01δ mode. A simple field model is introduced to analyze this resonator structure. Unlike other simple models, this model does not have the defect of low measurement accuracy of dielectric properties. Important factors affecting the dielectric properties measurements are introduced. Error sources for measurements are also discussed. The measurement accuracy is justified by comparing the results with those of other techniques. In addition, various methods for calculating the power factor and conducting loss and for measuring the conductivity of the conducting plates are discussed. The accuracies of certain of these methods have not previously been studied, but are given in this paper. The swept frequency capability was also studied. It was found that dielectric properties in microwave frequencies could be measured within a frequency range of 3 GHz

  12. Analytical solutions of nonlocal Poisson dielectric models with multiple point charges inside a dielectric sphere

    Science.gov (United States)

    Xie, Dexuan; Volkmer, Hans W.; Ying, Jinyong

    2016-04-01

    The nonlocal dielectric approach has led to new models and solvers for predicting electrostatics of proteins (or other biomolecules), but how to validate and compare them remains a challenge. To promote such a study, in this paper, two typical nonlocal dielectric models are revisited. Their analytical solutions are then found in the expressions of simple series for a dielectric sphere containing any number of point charges. As a special case, the analytical solution of the corresponding Poisson dielectric model is also derived in simple series, which significantly improves the well known Kirkwood's double series expansion. Furthermore, a convolution of one nonlocal dielectric solution with a commonly used nonlocal kernel function is obtained, along with the reaction parts of these local and nonlocal solutions. To turn these new series solutions into a valuable research tool, they are programed as a free fortran software package, which can input point charge data directly from a protein data bank file. Consequently, different validation tests can be quickly done on different proteins. Finally, a test example for a protein with 488 atomic charges is reported to demonstrate the differences between the local and nonlocal models as well as the importance of using the reaction parts to develop local and nonlocal dielectric solvers.

  13. Dielectric and photo-dielectric properties of TlGaSeS crystals

    Indian Academy of Sciences (India)

    A F Qasrawi; Samah F Abu-Zaid; Salam A Ghanameh; N M Gasanly

    2014-05-01

    The room temperature, dark and photo-dielectric properties of the novel crystals TlGaSeS are investigated in the frequency, intensity and biasing voltage having ranges of ~ 1–120 MHz, 14–40 klux and 0–1 V, respectively. The crystals are observed to exhibit a dark high frequency effective dielectric constant value of ∼ 10.65 × 103 with a quality factor of ∼ 8.84 × 104 at ∼ 120 MHz. The dielectric spectra showed sharp resonance–antiresonance peaks in the frequency range of ∼ 25–250 kHz. When photoexcited, pronounced increase in the dielectric constant and in the quality factor values with increasing illumination intensity are observed. Signal amplification up to ∼ 33% with improved signal quality up to ∼ 29% is attainable via photoexcitation. On the other hand, the illuminated capacitance–voltage characteristics of the crystals reflected a downward shift in the voltage biasing and in the built-in voltage of the device that is associated with increase in the uncompensated carrier density. The increase in the dielectric constant with increasing illumination intensity is ascribed to the decrease in the crystal's resistance as a result of increased free carrier density. The light sensitivity of the crystals, the improved dielectric properties and the lower biasing voltage obtained via photoexcitation and the well-enhanced signal quality factor of the crystals make them promising candidates for optical communication systems.

  14. Effect of vacuum-ultraviolet irradiation on the dielectric constant of low-k organosilicate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, H.; Shohet, J. L. [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Ryan, E. T. [GLOBALFOUNDRIES, Albany, New York 12203 (United States); Nishi, Y. [Stanford University, Stanford, California 94305 (United States)

    2014-11-17

    Vacuum ultraviolet (VUV) irradiation is generated during plasma processing in semiconductor fabrications, while the effect of VUV irradiation on the dielectric constant (k value) of low-k materials is still an open question. To clarify this problem, VUV photons with a range of energies were exposed on low-k organosilicate dielectrics (SiCOH) samples at room temperature. Photon energies equal to or larger than 6.0 eV were found to decrease the k value of SiCOH films. VUV photons with lower energies do not have this effect. This shows the need for thermal heating in traditional ultraviolet (UV) curing since UV light sources do not have sufficient energy to change the dielectric constant of SiCOH and additional energy is required from thermal heating. In addition, 6.2 eV photon irradiation was found to be the most effective in decreasing the dielectric constant of low-k organosilicate films. Fourier Transform Infra-red Spectroscopy shows that these 6.2 eV VUV exposures removed organic porogens. This contributes to the decrease of the dielectric constant. This information provides the range of VUV photon energies that could decrease the dielectric constant of low-k materials most effectively.

  15. Octasilsesquioxane-reinforced DGEBA and TGDDM epoxy nanocomposites: Characterization of thermal, dielectric and morphological properties

    International Nuclear Information System (INIS)

    Epoxy resin nanocomposites, based on the diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM), are prepared via in situ co-polymerization with 4,4'-diaminodiphenylsulfone (DDS) in the presence of octa-aminophenyl silsesquioxane (OAPS) at levels of up to 20 wt.% of the latter. The curing reaction involving epoxy, DDS and OAPS is investigated using Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the polyhedral oligomeric silsesquioxane (POSS) containing nanocomposites are higher than the corresponding neat epoxy systems at lower concentrations of POSS (≤3 wt.%). Thermogravimetric analysis indicates that the POSS-epoxy nanocomposites display high ceramic yields, suggesting improved flame retardancy. The increasing concentration of OAPS into epoxy-amine networks exhibits a decreasing trend in the values of dielectric constant compared with those values obtained from neat epoxy systems. The higher epoxy functionality present in TGDDM leads to nanocomposites which possess enhanced thermal stability and higher dielectric constants than the DGEBA-based nanocomposites. X-ray diffraction analysis reveals that the molecular level reinforcement of POSS cages occurs in both the cases of DGEBA- and TGDDM-based hybrid epoxy nanocomposites. Furthermore, homogeneous dispersion of POSS cages in the epoxy matrices is evidenced by scanning electron microscopy, which further confirms that the POSS molecule has become an integral part of the organic-inorganic inter-cross-linked network systems.

  16. Octasilsesquioxane-reinforced DGEBA and TGDDM epoxy nanocomposites: Characterization of thermal, dielectric and morphological properties

    Energy Technology Data Exchange (ETDEWEB)

    Nagendiran, Shanmugam [Department of Chemical Engineering, Anna University, Chennai 600 025 (India); Alagar, Muthukaruppan, E-mail: mkalagar@yahoo.com [Department of Chemical Engineering, Anna University, Chennai 600 025 (India); Hamerton, Ian [Chemical Sciences Division, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2010-05-15

    Epoxy resin nanocomposites, based on the diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM), are prepared via in situ co-polymerization with 4,4'-diaminodiphenylsulfone (DDS) in the presence of octa-aminophenyl silsesquioxane (OAPS) at levels of up to 20 wt.% of the latter. The curing reaction involving epoxy, DDS and OAPS is investigated using Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the polyhedral oligomeric silsesquioxane (POSS) containing nanocomposites are higher than the corresponding neat epoxy systems at lower concentrations of POSS ({<=}3 wt.%). Thermogravimetric analysis indicates that the POSS-epoxy nanocomposites display high ceramic yields, suggesting improved flame retardancy. The increasing concentration of OAPS into epoxy-amine networks exhibits a decreasing trend in the values of dielectric constant compared with those values obtained from neat epoxy systems. The higher epoxy functionality present in TGDDM leads to nanocomposites which possess enhanced thermal stability and higher dielectric constants than the DGEBA-based nanocomposites. X-ray diffraction analysis reveals that the molecular level reinforcement of POSS cages occurs in both the cases of DGEBA- and TGDDM-based hybrid epoxy nanocomposites. Furthermore, homogeneous dispersion of POSS cages in the epoxy matrices is evidenced by scanning electron microscopy, which further confirms that the POSS molecule has become an integral part of the organic-inorganic inter-cross-linked network systems.

  17. Structural and dielectric properties of thiazolium chlorobismuthate(III) and chloroantimonate(III)

    Science.gov (United States)

    Piecha, A.; Jakubas, R.; Kinzhybalo, V.; Lis, T.

    2008-09-01

    The crystal structures of [C 3H 4NS] 6[ M4Cl 18]·2H 2O ( M = Sb, Bi) consist of three nonequivalent thiazolium cations and discrete centrosymmetric anions [ M4Cl 18] 6-. The title compounds appear to be isomorphous and crystallize in the triclinic space group, P1¯ (at 100 K). One of three thiazolium cations was found to be disordered (two-site model). [C 3H 4NS] + cations are hydrogen bonded to [ M4Cl 18] 6- units and water molecules. The water molecules (O w) via the O-H…Cl hydrogen bonds are involved in the one-dimensional polymeric chains, which extend along the c-axis. The dielectric dispersion studies on two thiazolium analogs in the audio-frequency region disclosed complex relaxation processes. The dielectric response indicates the presence of two independent relaxators, which are characterized by polydispersive nature. The relaxation processes taking place in the both studied crystals are due to the motion of dipolar thiazolium cations.

  18. Trends of microwave dielectric materials for antenna application

    Science.gov (United States)

    Sulong, T. A. T.; Osman, R. A. M.; Idris, M. S.

    2016-07-01

    Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ɛr), high quality factor (Q f ≥ 5000GH z) and good temperature coefficient of resonant frequency (τf). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

  19. Observation of Cavity QED in thick dielectric films

    Science.gov (United States)

    Sarabi, Bahman; Ramanayaka, A. N.; Gladchenko, S.; Stoutimore, M. J. A.; Khalil, M. S.; Osborn, K. D.

    2013-03-01

    Cavity QED in amorphous dielectrics is investigated by measuring five linear superconducting resonators with thick dielectric films and capacitor volumes ranging from 80 μm3 to 5000 μm3. In the smallest volume dielectrics we observe additional resonances which may be explained by CQED, despite the dielectric volume which is many orders of magnitude larger than Josephson junction barrier volumes. In addition to the volume dependence of the CQED resonances, we will report on the stability of the resonances in time and the phase noise. This research allows new fundamental studies on TLS phenomena in meso-volume amorphous dielectrics.

  20. Dielectric measurements on PWB materials at microwave frequencies

    Indian Academy of Sciences (India)

    A Tanwar; K K Gupta; P J Singh; Y K Vijay

    2006-04-01

    In quest of finding new substrate for printed wiring board (PWB) having low dielectric constant, we have made PSF/PMMA blends and evaluated the dielectric parameters at 8.92 GHz frequency and at 35°C temperature. Incorporating PMMA in PSF matrix results in reduced dielectric constant than that of pure PSF. The dielectric parameters of pure PMMA and PSF films of different thicknesses have also been obtained at microwave frequencies. We have used dielectric data at microwave frequencies as a tool to evaluate optical constants, absorption index `’ and refractive index `’. The blends of PSF/PMMA may be used as base materials for PWBs.