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Suche nach „[Rychkov] [Dmitry]“ hat 106 Publikationen gefunden
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    NachhaltigTSZ Weißenburg

    Zeitschriftenartikel

    Y.A.O. Assagra, Altafim, R.A.P., J. do Carmo, R.A.C. Altafim, Dmitry Rychkov, Wirges, W., Gerhard, R.

    A new route to piezo-polymer transducers: 3D printing of polypropylene ferroelectrets

    IEEE Transactions on Dielectrics and Electrical Insulation, vol. 27, no. 5, pp. 1668-1674

    2020

    DOI: 10.1109/TDEI.2020.008461

    Abstract anzeigen

    Here, a promising approach for producing piezo-polymer transducers in a one-step process is presented. Using 3D-printing technology and polypropylene (PP) filaments, we are able to print a two-layered film structure with regular cavities of precisely controlled size and shape. It is found that the 3D-printed samples exhibit piezoelectric coefficients up to 200 pC/N, similar to those of other PP ferroelectrets, and their temporal and thermal behavior is in good agreement with those known of PP ferroelectrets. The piezoelectric response strongly decreases for applied pressures above 20 kPa, as the pressure in the air-filled cavities strongly influences the overall elastic modulus of ferroelectrets.

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    Zeitschriftenartikel

    Wang, J., Dmitry Rychkov, Q. Nguyen, Gerhard, R.

    Unexpected bipolar space-charge polarization across transcrystalline interfaces in polypropylene electret films

    Journal of Applied Physics, vol. 128, no. 13

    2020

    DOI: 10.1063/5.0022071

    Abstract anzeigen

    A double-layer transcrystalline polypropylene (PP) film with a flat central interface layer between its two transcrystalline layers is obtained by recrystallization from the melt between two polytetrafluoroethylene (PTFE) surfaces on both sides of the PP film. Its electret properties are studied and compared with those of a single-layer transcrystalline PP film re-crystallized in contact with only one PTFE surface. Within experimental uncertainty, the two types of transcrystalline films exhibit the same thermal properties and crystallinities. After thermal poling, however, two hetero-charge layers of opposite polarity are found on the internal interfaces of the double-layer transcrystalline films and may together be considered as micrometer-sized dipoles. The unexpected phenomenon does not occur in single-layer transcrystalline samples without a central interface layer, suggesting that the interfaces between the transcrystalline layers and the micrometer-thick central interface layer may be the origin of deeper traps rather than the crystalline structures in the transcrystallites or the spherulites. The origin of the interfacial charges was also studied by means of an injection-blocking charging method, which revealed that intrinsic charge carriers introduced during recrystallization are most likely responsible for the interfacial charges. It is fascinating that a material as familiar as PP can exhibit such intriguing properties with a special bipolar space-charge polarization across the central interface layer after quasi-epitaxial surface moulding into a double-layer transcrystalline form. In addition to applications in electret (micro-)devices for electro-mechanical transduction, the highly ordered structures may also be employed as a new paradigm for studying charge storage and transport in polymer electrets and in dielectrics for DC electrical insulation.

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    Zeitschriftenartikel

    Wang, J., Dmitry Rychkov, Q. Nguyen, Gerhard, R.

    The influence of orthophosphoric-acid surface modification on charge-storage enhancement in polypropylene electrets

    Journal of Applied Physics, vol. 128, no. 3

    2020

    DOI: 10.1063/5.0013805

    Abstract anzeigen

    Bipolar electrets from polypropylene (PP) are essential, e.g., in electret air filters and in cellular-foam ferroelectrets. Therefore, the mechanism of surface-charge stability enhancement on PP electrets via orthophosphoric-acid surface treatment is investigated in detail. It is shown that the significant charge-stability enhancement can be mainly attributed to deeper surface traps originating from deposited chemicals and topographic features on the modified surfaces. Thermally stimulated discharge of chemically treated and non-treated PP films with different surface-charge densities is used to test the limits of the newly formed deep traps in terms of the capacity for hosting surface charges. When the initial surface-charge density is very high, more charges are forced into shallower original traps on the surface or in the bulk of the treated PP samples, reducing the effect of the deeper surface traps brought by the surface modification. The well-known crossover phenomenon (of the surface-charge decay curves) has been observed between modified PP electrets charged to ±2 kV and to ±3  kV. Acoustically probed charge distributions in the thickness direction of PP electrets at different stages of thermal discharging indicate that the deep surface trapping sites may have preference for negative charges, resulting in the observed asymmetric charge stability of the modified PP films.

    NachhaltigTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Dmitry Rychkov

    Controlling Trapping Parameters via Polymer Structure and Composition? (Keynote)

    Book of Abstracts of the 17th International Symposium on Electrets (ISE17) 2019 (2-6 September 2019, University of Limerick, Ireland)

    2019

    Abstract anzeigen

    Space-charge electrets are usually fabricated from non-polar polymers. Such materials as polyethylene, polypropylene, polytetrafluoroethylene and its copolymers are used in electret microphones, filters, radiation dosimeters, and different kinds of electromechanical transducers, as well as in biomedical devices [1]. The key factor in all these applications is both thermal and temporal stability of the electret charge. However, the existing materials do not always possess the required level of charge stability. Or, on the other hand, a material may be an excellent electret, but lack in processability, cost efficiency etc. In general, there is a need to be able to control electret properties of commercially available polymer materials used in various electroactive applications. Here we will discuss how changes in chemical composition and structural changes can influence electret charge storage and transport in non-polar polymers.

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    Beitrag (Sammelband oder Tagungsband)

    Q. Nguyen, Wang, J., Dmitry Rychkov, Gerhard, R.

    Depth Profile and Transport of Positive and Negative Charge in Surface (2-D) and Bulk (3-D) Nanocomposite Films

    Proceedings of the 2nd International Conference on Electrical Materials and Power Equipment Electrical (ICEMPE) [7-10 April 2019; Guangzhou, China]

    2019

    ISBN: 978-1-5386-8434-4

    DOI: 10.1109/ICEMPE.2019.8727256

    Abstract anzeigen

    In the present study, the charge distribution and the charge transport across the thickness of 2- and 3-dimensional polymer nanodielectrics was investigated. Chemically surface-treated polypropylene (PP) films and low-density polyethylene nanocomposite films with 3 wt % of magnesium oxide (LDPE/MgO) served as examples of 2-D and 3-D nanodielectrics, respectively. Surface charges were deposited onto the non-metallized surfaces of the one-side metallized polymer films and found to broaden and to thus enter the bulk of the films upon thermal stimulation at suitable elevated temperatures. The resulting space-charge profiles in the thickness direction were probed by means of Piezoelectrically-generated Pressure Steps (PPSs). It was observed that the chemical surface treatment of PP which led to the formation of nano-structures or the use of bulk nanoparticles from LDPE/MgO nanocomposites enhance charge trapping on or in the respective polymer films and also reduce charge transport inside the respective samples.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Wang, J., Dmitry Rychkov, Gerhard, R.

    Influence of Charge Density on Charge Decay in Chemically Modified Polypropylene Films

    Proceedings of the IEEE 2nd International Conference on Dielectrics, Budapest, Hungary

    2018

    ISBN: 978-1-5386-6389-9

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    F. He, Wang, J., Dmitry Rychkov, Schulze, M., Wirges, W., Gerhard, R.

    Senskin deformable silicone-elastomer sensors for structural health monitoring: assessment of strain sensitivity and correction for thermal expansion

    Proceedings of the 8th International Conference on Electromechanically Active Polymer (EAP) Transducers & Artificial Muscles , Valpré Ecully - Lyon, France

    2018

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Dmitry Rychkov, F. He, Wang, J., Schulze, M., G. Gidion, Wirges, W., Gerhard, R.

    Soft Stretchable All-Silicone Sensor for Transport-Infrastructure Monitoring

    Sensoren und Messsysteme 2018 19. ITG-/GMA-Fachtagung

    2018

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Rychkov, A. A., V. Stojharov, Kuznetsov, A., Dmitry Rychkov

    The Influence of Recrystallization Regimes on Electret Charge Stability in Low-Density Polyethylene Films

    Proceedings of the IEEE 2nd International Conference on Dielectrics, Budapest, Hungary

    2018

    ISBN: 978-1-5386-6389-9

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Zeitschriftenartikel

    Cheilakou, E., Tsopelas, N., Anastasopoulos, A., Kourousis, D., Dmitry Rychkov, Gerhard, R., Frankenstein, B., Amditis, A., Damigos, Y., Bouklas, C.

    Strain monitoring system for steel and concrete structures

    Procedia Structural Integrity, vol. 10, pp. 25-32

    2018

    DOI: 10.1016/j.prostr.2018.09.005

    Abstract anzeigen

    The present work is part of a collaborative H2020 European funded research project called SENSKIN, that aims to improve Structural Health Monitoring (SHM) for transport infrastructure through the development of an innovative monitoring and management system for bridges based on a novel, inexpensive, skin-like sensor. The integrated SENSKIN technology will be implemented in the case of steel and concrete bridges, and tested, field-evaluated and benchmarked on actual bridge environment against a conventional health monitoring solution developed by Mistras Group Hellas. The main objective of the present work is to implement the autonomous, fully functional strain monitoring system based on commercially available off-the-shelf components, that will be used to accomplish direct comparison between the performance of the innovative SENSKIN sensors and the conventional strain sensors commonly used for structural monitoring of bridges. For this purpose, the mini Structural Monitoring System (mini SMS) of Physical Acoustics Corporation, a comprehensive data acquisition unit designed specifically for long-term unattended operation in outdoor environments, was selected. For the completion of the conventional system, appropriate foil-type strain sensors were selected, driven by special conditioners manufactured by Mistras Group. A comprehensive description of the strain monitoring system and its peripheral components is provided in this paper. For the evaluation of the integrated system’s performance and the effect of various parameters on the long-term behavior of sensors, several test steel pieces instrumented with different strain sensors configurations were prepared and tested in both laboratory and field ambient conditions. Furthermore, loading tests were performed aiming to validate the response of the system in monitoring the strains developed in steel beam elements subject to bending regimes. Representative results obtained from the above experimental tests have been included in this paper as well.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Zeitschriftenartikel

    Dmitry Rychkov, Altafim, R.A.P.

    Template-based fluoroethylenepropylene ferroelectrets with enhanced thermal stability of piezoelectricity

    Journal of Applied Physics, vol. 124, no. 17

    2018

    DOI: 10.1063/1.5041374

    Abstract anzeigen

    In ferroelectrets, the piezoelectricity stems from the charges of both polarities trapped on the inner surfaces of the cavities in the material, so that its thermal stability is defined by the stability of the respective charges. In the present work, a template-based lamination technique has been employed to fabricate tubular-channel ferroelectrets from fluoroethylenepropylene (FEP) films. It has been shown that the piezoelectricity in FEP ferroelectrets decays at relatively low temperatures due to the inherently lower thermal stability of the positive charge. In order to improve charge trapping, we have treated both FEP films and inner surfaces of the ferroelectret cavities with titanium-tetrachloride vapor, using the atomic-layer-deposition technique. Using surface-potential-decay measurements on FEP films, we have found that the charge-decay curves shift by more than 100 ∘C to the higher temperatures as a result of the surface treatment. Direct measurements of piezoelectric d33 coefficients as a function of temperature have shown that the piezoelectric stability is likewise improved with the d33-decay curves shifted by 60 ∘C to the right. The improvement of electret/ferroelectret properties can be attributed to the formation of the deeper traps on the chemically modified FEP surface. SEM micrographs and EDS analysis reveal island-like structures with titanium- and oxygen-containing species that can be responsible for the deeper trapping of the electret charges.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Zeitschriftenartikel

    Dmitry Rychkov, Gerhard, R., Kuznetsov, A., Rychkov, A. A.

    Influence of Charge Density on the Trap-Energy Spectrum in Fluoroethylenepropylene Copolymer Films with Chemically Modified Surfaces

    IEEE Transactions on Dielectrics and Electrical Insulation, vol. 25, no. 3, pp. 840-844

    2018

    DOI: 10.1109/TDEI.2018.007437

    Abstract anzeigen

    Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films were treated with titanium-tetrachloride vapor by means of molecular-layer deposition. The treatment leads to considerable improvements of the electret-charge stability on positively charged films. A slight improvement is also observed for negatively charged films. In line with our previous findings, we attribute the improvement in electret properties to the formation of deeper traps on the chemically modified polymer surfaces. Here, we investigate the influence of the charge density on electret stability of FEP films with modified surfaces. Trap-energy spectra obtained from thermally-stimulated-discharge measurements indicate that the charge stability on modified FEP films depends on how the surface traps are populated and on the availability of additional deeper traps.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Wirges, W., Qiu, X., Dmitry Rychkov, Gerhard, R.

    Pressure dependence of the piezoelectric d33 coefficient and the cellular-foam structure in polypropylene ferro- and piezoelectrets

    Proceedings of the 16th International Symposium on Electrets, Leuven, Belgium

    2017

    ISBN: 978-90-8649-798-0

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Q. Nguyen, Wang, J., Dmitry Rychkov, Gerhard, R.

    Piezoelectrically generated Pressure Steps (PPS) for studying charge distributions on corona-charged Polypropylene (PP) films

    Proceedings of the 16th International Symposium on Electrets, Leuven, Belgium

    2017

    ISBN: 978-90-8649-798-0

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Wang, J., Dmitry Rychkov, Gerhard, R.

    Influence of foreign chemical structures from nitric acid treatment on electret and electrical-insulation properties of polypropylene

    Proceedings of the 16th International Symposium on Electrets, Leuven, Belgium

    2017

    ISBN: 978-90-8649-798-0

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Dmitry Rychkov, Gerhard, R., Kuznetsov, A., Rychkov, A. A.

    Trap-energy spectrum in corona-charged polytetrafluoroethylene (PTFE) electret films with modified surfaces

    Proceedings of the 16th International Symposium on Electrets, Leuven, Belgium

    2017

    ISBN: 978-90-8649-798-0

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Dmitry Rychkov, Schulze, M., Gerhard, R.

    Soft Capacitive Sensors for Structural Health Monitoring

    Proceedings of the 14th International Conference “Dielectrics 2017"

    2017

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Zeitschriftenartikel

    Loupos, K., Damigos, Y., Amditis, A., Gerhard, R., Dmitry Rychkov, Wirges, W., Schulze, M., Lenas, S.-A., Chatziandreoglou, C., Malliou, C.M., Tsaoussidis, V., Brady, K., Frankenstein, B.

    Structural health monitoring system for bridges based on skin-like sensor

    IOP Conference Series: Materials Science and Engineering, vol. 236, no. Proceedings of BESTInfra2017 - Building up Efficient and Sustainable TransportInfrastructure 2017

    2017

    DOI: 10.1088/1757-899X/236/1/012100

    Abstract anzeigen

    Structural health monitoring activities are of primal importance for managing transport infrastructure, however most SHM methodologies are based on point-based sensors that have limitations in terms of their spatial positioning requirements, cost of development and measurement range. This paper describes the progress on the SENSKIN EC project whose objective is to develop a dielectric-elastomer and micro-electronics-based sensor, formed from a large highly extensible capacitance sensing membrane supported by advanced microelectronic circuitry, for monitoring transport infrastructure bridges. Such a sensor could provide spatial measurements of strain in excess of 10%. The actual sensor along with the data acquisition module, the communication module and power electronics are all integrated into a compact unit, the SENSKIN device, which is energy-efficient, requires simple signal processing and it is easy to install over various surface types. In terms of communication, SENSKIN devices interact with each other to form the SENSKIN system; a fully distributed and autonomous wireless sensor network that is able to self-monitor. SENSKIN system utilizes Delay-/Disruption-Tolerant Networking technologies to ensure that the strain measurements will be received by the base station even under extreme conditions where normal communications are disrupted. This paper describes the architecture of the SENSKIN system and the development and testing of the first SENSKIN prototype sensor, the data acquisition system, and the communication system.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Zeitschriftenartikel

    Wang, J., Dmitry Rychkov, Gerhard, R.

    Chemical modification with orthophosphoric acid enhances surface-charge stability on polypropylene electrets

    Applied Physics Letters, vol. 110, no. 19

    2017

    DOI: 10.1063/1.4983348

    Abstract anzeigen

    The low surface-charge stability of polypropylene (PP) frequently limits its application as an electret material. In this paper, we demonstrate how the treatment of PP-film surfaces with orthophosphoric acid (H3PO4) enhances their charge stability. To discriminate between the effects of chemical modification and thermal treatment, as-received and annealed PP films are used as reference samples. The electret properties of treated and non-treated PP films are characterized with thermally stimulated discharge (TSD) and isothermal surface-potential decay (ISPD) experiments, from which considerable improvement in thermal and temporal charge stability is observed for samples modified with H3PO4. The half-value temperature (T1∕2) observed on TSD curves of chemically treated PP increases to 131 and 145 °C for positive and negative charges, respectively. The enhancement might be attributed to the phosphoric compounds detected on the H3PO4-modified surfaces via attenuated-total-reflection infrared spectroscopy. Deeper surface traps formed at the “foreign” phosphorus-containing structures are able to capture the charges over longer time periods and at higher temperatures, thus leading to significant improvements in the temporal and thermal surface-charge stabilities of PP electrets.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTSZ Weißenburg

    Beitrag (Sammelband oder Tagungsband)

    Loupos, K., Amditis, A., A. Tsertou, Damigos, Y., Gerhard, R., Dmitry Rychkov, Wirges, W., V. Kalidromitis, S. Camarinopoulos, S. Lenas, V. Tsaoussidisa, Anastasopoulos, A., K. Lenz, S. Schneider, M. Hill, A. Adesiyun, Frankenstein, B.

    Skin-like Sensor Enabled Bridge Structural Health Monitoring System

    Proceedings of the 8th European Workshop On Structural Health Monitoring (EWSHM 2016), Bilbao, Spain

    2016

    Abstract anzeigen

    Structural Health Monitoring (SHM) has an important role in the management of transport infrastructure. However, most SHM techniques are based on data obtained from dense networks of point-based sensors (rather than sparse networks of spatial sensors) and so, inrelative terms, they are costly to implement. Most commercially available strain sensors have a limited maximum range - typically 1% to 2% - and are not well-suited to providing information of a severe loss of structural integrity. The SENSKIN project develops a dielectric-elastomer and micro-electronics-based skin-like sensor, based on the use of a largehighly extensible capacitance sensing membrane and advanced micro-electronic circuitry, for monitoring transport infrastructure - such as bridges. The sensor will provide spatial measurements of strain of more than 10% and is being designed to (a) require low power to operate, (b) be easy to install (c) have a comparable or lower cost than conventional strain sensors, (d) allow simple signal processing, and (e) have the ability to self-monitor and self-report. The system will support the new and emerging technology of Delay/Disruption-Tolerant Networking to secure that strain measurements acquired will reach the base station even under extreme conditions where communications may be disrupted. SENSKIN also develops a Decision-Support-System (DSS) for proactive condition-based structural interventions under normal operating conditions and reactive emergency intervention following an extreme event. In assessing potential rehabilitation options, the DSS will use the data supplied by the SENSKIN sensors together with advanced structural analysis models, whilst taking account of the lifecycle economic, social and environmental implications. The overall monitoring system will be evaluated and benchmarked on actual bridges of Egnatia Highway (Greece) and Bosporus Bridge (Turkey). This paper describes the concept and principles of the SENSKIN sensing system, and its various components with attention to end-user requirements, specifications and system architecture.