Дисертації з теми "Polymer Metal Composite"
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Mokhtari, Morgane. "FeCr composites : from metal/metal to metal/polymer via micro/nano metallic foam, exploitation of liquid metal dealloying process." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI088/document.
Повний текст джерелаNanoporous metals have attracted considerable attention for their excellent functional properties. The first developed technique used to prepare such nanoporous noble metals is dealloying in aqueous solution. Porous structures with less noble metals such as Ti or Fe are highly desired for various applications including energy-harvesting devices. The less noble metals, unstable in aqueous solution, are oxidized immediately when they contact water at a given potential so aqueous dealloying is only possible for noble metals. To overcome this limitation, a new dealloying method using a metallic melt instead of aqueous solution was developed. Liquid metal dealloying is a selective dissolution phenomenon of a mono-phase alloy solid precursor: one component (referred as soluble component) being soluble in the metallic melt while the other (referred as targeted component) is not. When the solid precursor contacts the metallic melt, only atoms of the soluble component dissolve into the melt inducing a spontaneously organized bi-continuous structure (targeted+sacrificial phases), at a microstructure level. This sacrificial phase can finally be removed by chemical etching to obtain the final nanoporous materials. Because this is a water-free process, it has enabled the preparation of nanoporous structures in less noble metals such as Ti, Si, Fe, Nb, Co and Cr. The objectives of this study are the fabrication and the microstructure and mechanical characterization of 3 different types of materials by dealloying process : (i) metal/metal composites (FeCr-Mg), (ii) porous metal (FeCr) (iii) metal/polymer composites (FeCr-epoxy resin). The last objective is the evaluation of the possibilities to apply liquid metal dealloying in an industrial context. The microstructure study was based on 3D observation by X-ray tomography and 2D analysis with electron microscopy (SEM, SEM-EDX, SEM-EBSD). To have a better understanding of the dealloying, the process was followed in situ by X-ray tomography and X-ray diffraction. Finally the mechanical properties were evaluated by nanoindentation and compression
Bhat, Nikhil Dilip. "Modeling and precision control of ionic polymer metal composite." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1152.
Повний текст джерелаYusuf, Suhaila Mohamad. "Development of an ionic polymer metal composite (IPMC) microgripper." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.550855.
Повний текст джерелаAnyaogu, Kelechi C. "Stabilized metal nanoparticle-polymer composites preparation, characterization and potential applications /." Bowling Green, Ohio : Bowling Green State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1222126708.
Повний текст джерелаGraham, Adam. "Electrical properties and vapour sensing characteristics of a novel metal-polymer composite." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/2376/.
Повний текст джерелаSkinner, Anna Penn. "Ion Conducting Polyelectrolytes in Conductive Network Composites and Humidity Sensing Applications for Ionic Polymer-Metal Composite Actuators." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71683.
Повний текст джерелаMaster of Science
Sun, Weizhen. "Microstructure-based FE Modeling and Measurements of Magnetic Properties of Polymer Matrix-Metal Composites." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/74946.
Повний текст джерелаMaster of Science
Hands, Philip James Walton. "Vapour sensing applications and electrical conduction mechanisms of a novel metal-polymer composite." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/4084/.
Повний текст джерелаJadhav, Niteen. "Novel Conducting Polymer Containing Composite Coatings for the Corrosion Protection of Metal Alloys." Diss., North Dakota State University, 2013. https://hdl.handle.net/10365/27037.
Повний текст джерелаU.S. Army Research Laboratory (Grant No. W911NF-09-2-0014, W911NF-10-2-0082, and W911NF-11-2-0027)
Seo, Geon S. "Time evolution of current and displacement of ion-exchange polymer/metal composite actuators." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280748.
Повний текст джерелаJi, Yijie. "Metal Organic Frameworks Derived Nickel Sulfide/Graphene Composite for Lithium-Sulfur Batteries." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron152233332526446.
Повний текст джерелаBhaskar, A. "Design and synthesis of metal organic framework (MOF) - polymer composite membranes for gas separation." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2015. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2063.
Повний текст джерелаTiwari, Rashi. "Modeling and characterization of the mechanoelectric response of ionic polymer metal composite (IPMC) energy harvesters." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3387826.
Повний текст джерелаKaleli, Kadir. "Nano Structural Metal Composites: Synthesis, Structural And Thermal Characterization." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609674/index.pdf.
Повний текст джерелаCr <
Au3+ indicating stronger coordination in the same order.
Francart, Charles. "Experimental and numerical study of the mechanical behavior of metal/polymer multilayer composite for ballistic protection." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAD033/document.
Повний текст джерелаThe present study deals with the development of a numerical model to evaluate the ballistic performance of a polymer/metal multilayer structure sintered by SPS. The materials are an aluminum alloy 7020 and an amorphous thermoplastic polyimide which are then assembled using an epoxy resin. The mechanical behavior of these three materials has been studied over wide ranges of strain rates (from 0.0001 / s to 50,000 / s) and temperatures (from -70 °C to 500 °C) corresponding to the extreme conditions encountered during impacts at high velocities. In order to improve the accuracy of the results, analytical approaches have been developed both for the modeling of the metal and for the polymers. After the calibration of the models, these models were implemented in ABAQUS® / Explicit (finite elements) via VUMAT subroutines in FORTRAN code. Ball impact tests at high velocities were performed on monolayer targets to validate numerical models. Numerous configurations of multilayer composites were then studied numerically and their ballistic performances have been compared
Davidson, Jacob Daniel. "Actuation and Charge Transport Modeling of Ionic Liquid-Ionic Polymer Transducers." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/31204.
Повний текст джерелаMaster of Science
Osiecki, Tomasz, Colin Gerstenberger, Holger Seidlitz, Alexander Hackert, and Lothar Kroll. "Behavior of Cathodic dip Paint Coated Fiber Reinforced Polymer/Metal Hybrids." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-175536.
Повний текст джерелаGasparin, Alexandre Luis. "Adesão metal-polímero: dispositivos de medição e correlações físico-químicas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/37831.
Повний текст джерелаOne of the methods to quantify the interface strength of composites is to measure the tensile stress necessary to separate a film from the substrate surface. Such value is often used as a project parameter to develop the composite. However, most of methods cannot avoid the interference of the cohesion bulk failures from the film/substrate adhesion measures. In this work a new method is proposed in order to eliminate the influence of the cohesion shear failure inherent to the delaminated film of the normal adhesion stress measured by the standard method. The new method has proved to work and their results have become more accurate than the standard pull-off method. The experiment consisted in delaminate a copper film deposited by physical vapor evaporation (PVD) through electron gun on four polymers: polypropylene (PP), polyamide 6 (PA 6), high impact polystyrene (HIPS) and polyethylene terephthalate (PET). The Rutherford backscattering spectrometry was used to characterize the films and the contact angle analysis to characterize the interfaces. The polymer surfaces have also been modified to verify the adhesion strengths of the copper film through sanding and flaming processes to validate the new method. Finally the substrates delaminated were analyzed for both methods, standard and proposed, through optical and scanning electron microscopies, proving that only the new method is effective in pulling-off the metal/polymer interface without the cohesive failure influence of the copper film.
Dogruer, Deniz. "The development of a hydrodynamic model for the segmented ionic polymer metal composite (IPMC) for underwater applications and the potential use of IPMCs for energy harvesting." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1438915.
Повний текст джерелаShen, Yubin. "The chemical and mechanical behaviors of polymer / reactive metal systems under high strain rates." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45804.
Повний текст джерелаYang, Xiaojiao. "Synthesis and Characterization of Hybrid Metal-Metallic Oxide Composite Nanofibers by Electrospinning and Their Applications." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1022/document.
Повний текст джерелаWe present in this manuscript the elaboration by Electrospinning (ES) process of hybrid metal-metallic oxide composite (HMMOC) nanofibers (NFs), and their physical-chemical characterizations. Their applications, especially the photocatalysis of TiO2-Au composite NFs for photocatalytic degradation for methylene blue (MB) in an aqueous solution and WO3-Au composite NFs for gas sensing of the volatile organic compounds (VOCs) have been investigated. According to the performance evaluation results as photocatalyst or gas sensors, the influence of many parameters have been studied: gold ions concentration, the way to introduce them into or at the NFs surface, typically by mixing them into the polymeric solution (composed of PVP, PAN, or PVA with the metallic oxide precursor) before the ES process or by simple droplet deposition onto the NFs after ES process, and finally the annealing treatment. This latter plays an important role since it both removes the organic components of the polymeric solution, thus forming the metal oxide and in-situ participates to the Au reduction.Concerning the photocatalytic properties, an optimized HMMOC material based on TiO2 NFs including 10 nm Au nanoparticles (NPs) has been obtained and shows 3 times significantly improvement of MB degradation compared to pure TiO2 NFs and the commercial catalyst P25. For gas sensing elaboration, we have shown that a HMMOC material based on WO3 NFs decorated at their surface with 10 nm Au NPs can exhibit 60 times higher response and significantly improved selectivity toward n-butanol compared with pure WO3 NFs
Vickers, Jason Aaron. "The development and implementation of an ionic-polymer-metal-composite propelled vessel guided by a goal-seeking algorithm." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/5936.
Повний текст джерелаMallavarapu, Kiran. "Feedback Control of Ionic Polymer Actuators." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34154.
Повний текст джерелаMaster of Science
Zedde, Nicola. "Dynamic mechanical-thermal, microstructural and mechanical analysis of ultra-light polymer-metal composites: influence of forming." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Знайти повний текст джерелаMARCHISIO, SILVIA. "Composite Materials reinforced by Carbon Nanotubes." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506164.
Повний текст джерелаKhdhayyer, Muhanned. "Mixed matrix membranes comprising metal organic frameworks and high free volume polymers for gas separations." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/mixed-matrix-membranes-comprising-metal-organic-frameworks-and-high-free-volume-polymers-for-gas-separations(172f6a4f-a531-44ae-979c-bbbd170f33db).html.
Повний текст джерелаHu, Qingchun. "Fabrication and characterization of poly(amide-imides)/TiO₂ nanocomposite gas separation membranes." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-10022008-063009/.
Повний текст джерелаDiaz, Mendoza Alvaro. "Conception of a fibrous composite material for the retention of heavy metals." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI125.
Повний текст джерелаHeavy metal contamination is a current problem which affects the ecosystems and their constituent organisms. This problem has been worldwide recognized as one of the biggest challenges of our time. Since the middle of the last century, innovations in the material science field have developed new methods to confront this risk, with techniques such as chemical precipitation or flotation. However, there is still significant room for improvement in this line. Furthermore, recent research has explored how to combine biomolecules such as proteins with materials like polymers to create more active solutions. This thesis work seeks to create a prototype hybrid biosorbent material capable to capture specifically the divalent metal ions Ni(II), Cd(II) and Pb(II) thanks to the presence of a synthetic metalloprotein in its structure. To address this objective, the thesis work focuses on the development of a synthetic metalloprotein capable to specifically capture the three target metal ions, from the in silico conception to its in vivo synthesis. On the other hand, the biosorbent material support is processed with the electrospinning technique that consists of a fibrous membrane material, being optimized to host the synthetic metalloprotein in its structure. Additionally, a method to integrate the metalloprotein into the polymeric support is researched. This is achieved by means of a grafting route through surface modified silica nanoparticles. At the end, the integration of both components creates the expected prototype synthetic biosorbent material. This material has been characterized to evaluate its capacity to adsorb the three metal ions of interest, providing some trends of the future perspectives for further development to create more efficient materials for the industry
Park, Jong Keun. "Anisotropic Morphologies and Properties in Perfluorosulfonate Ionomer-Based Materials." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/40486.
Повний текст джерелаPh. D.
Nishikitani, Yoshinori. "Polymères et oligomères conducteurs : matériaux pour l'électronique." Paris 13, 1989. http://www.theses.fr/1989PA132005.
Повний текст джерелаJain, Vaibhav. "Applications of Layer-by-Layer Films in Electrochromic Devices and Bending Actuators." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28907.
Повний текст джерелаPh. D.
MIGLIORINI, LORENZO. "DEVELOPMENT OF FUNCTIONAL NANOCOMPOSITE MATERIALS TOWARDS BIODEGRADABLE SOFT ROBOTICS AND FLEXIBLE ELECTRONICS." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/704286.
Повний текст джерелаFerreira, Henrique Perez. "Modificação de poli(fluoreto de vinilideno) induzida por radiação gama para aplicação como compósito ionomérico de metal-polímero." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-07112012-073635/.
Повний текст джерелаGamma-radiation-induced grafting of styrene into poly(vinylidene fluoride) (PVDF) films with 0.125 mm thickness at doses from 1 to 100 kGy in the presence of a styrene/N,N- dimethylformamide (DMF) solution (1:1, v/v) and styrene/toluene (1:1, v/v) at dose rate of 5 kGy h-1 was carried out by simultaneous method under nitrogen atmosphere at room temperature, using gamma rays from a Co-60. After grafting reactions, the polymer was then sulfonated in chlorosulfonic acid/1,2-dichloroethane (2 and 10%) for 3 hours. The films were characterized before and after modification by calculating the degree of grafting (DOG), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). DOG results show that grafting increases with dose, and varies enormously depending on the solvent used, with DOGs about 20 times greater in DMF than in toluene. It was possible to confirm the grafting of styrene by FT-IR due to the appearance of the new characteristic peaks and by the TG and DSC which exhibited changes in the thermal behavior of the grafted/sulfonated material. Sulfonated material was also characterized by ion exchange capacity (IEC) showed that both DOG and sulfonic acid concentration increase IEC values. Results showed that it is possible to obtain materials with ion exchange capacity of possible application as ionic polymer-metal composites.
Nestler, Daisy Julia. "Beitrag zum Thema VERBUNDWERKSTOFFE - WERKSTOFFVERBUNDE." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-134459.
Повний текст джерелаComplex property profiles require increasingly advanced composite materials and material compounds, including the rapid deployment of new production technologies, because the monolithic material or a single material can no longer satisfy today's complex requirements. Future material systems are fundamentally important to growth markets, in which they have an economically key position. Tailor-made lightweight materials (tailor-made composites) with an adapted design are needed. These concepts have to be developed to design the optimum combination of components. This requires material-specific knowledge and the ability to make correlations, as well as the design of complex technologies. Continuous large-scale and mass production (in-line, in-situ), thus reducing the costs of previously expensive composite materials and material compounds, is also necessary. The present work spans the entire field of composite materials and material compounds in a comparable and comparative manner and abstract form. A summarizing publication on this still very new, but already broad-based scientific field is not yet available. The separation of the individual, firmly divided groups of the composite materials is the reason for this. Cross-connections are rarely made. The objective of this work is to compensate to some extent for this deficiency. Special consideration is given to definitions and classifications, manufacturing processes and the properties of the materials. Clear structures and overviews are presented. Mapping established and new technologies will contribute to the stability of the terms "mixed material compounds" and "hybrid material compounds". In addition, the problem of recycling and recycling technologies is discussed. In summary, areas for future research and development projects will be specified. Generalized concepts for tailor-made composite materials and material compounds are proposed ("adjusting screw scheme") with an eye toward various production routes, especially for semi-finished products and components, and the associated findings. These general material concepts are applied to own current research projects pertaining to metal-matrix and polymer-matrix composites and hybrid material compounds. Research fields for future projects are extrapolated. Particular attention is paid to hybrid material compounds as the mainstay of future developments in lightweight construction. In-line and in-situ processes play a key role for large-scale, cost- and resource-efficient production
Liang, Wenfeng. "Metal Organic Composites Derived Tin Dioxide/C Nanoparticles For Sodium-Ion Battery." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460304081.
Повний текст джерелаNestler, Daisy Julia. "Beitrag zum Thema VERBUNDWERKSTOFFE - WERKSTOFFVERBUNDE: Status quo und Forschungsansätze." Doctoral thesis, Universitätsverlag Chemnitz, 2012. https://monarch.qucosa.de/id/qucosa%3A20009.
Повний текст джерелаComplex property profiles require increasingly advanced composite materials and material compounds, including the rapid deployment of new production technologies, because the monolithic material or a single material can no longer satisfy today's complex requirements. Future material systems are fundamentally important to growth markets, in which they have an economically key position. Tailor-made lightweight materials (tailor-made composites) with an adapted design are needed. These concepts have to be developed to design the optimum combination of components. This requires material-specific knowledge and the ability to make correlations, as well as the design of complex technologies. Continuous large-scale and mass production (in-line, in-situ), thus reducing the costs of previously expensive composite materials and material compounds, is also necessary. The present work spans the entire field of composite materials and material compounds in a comparable and comparative manner and abstract form. A summarizing publication on this still very new, but already broad-based scientific field is not yet available. The separation of the individual, firmly divided groups of the composite materials is the reason for this. Cross-connections are rarely made. The objective of this work is to compensate to some extent for this deficiency. Special consideration is given to definitions and classifications, manufacturing processes and the properties of the materials. Clear structures and overviews are presented. Mapping established and new technologies will contribute to the stability of the terms "mixed material compounds" and "hybrid material compounds". In addition, the problem of recycling and recycling technologies is discussed. In summary, areas for future research and development projects will be specified. Generalized concepts for tailor-made composite materials and material compounds are proposed ("adjusting screw scheme") with an eye toward various production routes, especially for semi-finished products and components, and the associated findings. These general material concepts are applied to own current research projects pertaining to metal-matrix and polymer-matrix composites and hybrid material compounds. Research fields for future projects are extrapolated. Particular attention is paid to hybrid material compounds as the mainstay of future developments in lightweight construction. In-line and in-situ processes play a key role for large-scale, cost- and resource-efficient production.
Olea, Mejia Oscar Fernando. "Micro and nano composites composed of a polymer matrix and a metal disperse phase." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc5135/.
Повний текст джерелаBae, Tae-Hyun. "Engineering nanoporous materials for application in gas separation membranes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42712.
Повний текст джерелаAnyaogu, Kelechi Chigboo. "Stabilized Metal Nanoparticle-Polymer Composites: Preparation, Characterization and Potential Applications." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1222126708.
Повний текст джерелаSafa, Meer N. "Poly (Ionic Liquid) Based Electrolyte for Lithium Battery Application." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3746.
Повний текст джерелаKoo, Yiu, and 顧耀. "Synthesis of metal-containing thiophene-based conjugated polymers for photovoltaic applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41897262.
Повний текст джерелаKoo, Yiu. "Synthesis of metal-containing thiophene-based conjugated polymers for photovoltaic applications." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41897262.
Повний текст джерелаClaude, Elisabeth. "Synthèse et optimisation des propriétés magnétiques et morphologiques de poudres d'alliages terres rares-métaux de transition par le procédé de réduction-diffusion (ORD), destinées à l'élaboration d'aimants permanents composites à matrice polymère." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0126.
Повний текст джерелаXue, Siqi. "Organic-modifier-free pathways for the preparation of polymer-metal oxide nanocomposites." Diss., Connect to online resource - MSU authorized users, 2007.
Знайти повний текст джерелаCorradi, Roberto. "Conducting polymer-silica colloidal composites." Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263866.
Повний текст джерелаJoshi, Sharmad Vinod. "Characterization of 3D printed metal oxide composite polymers." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1595511295182678.
Повний текст джерелаBaccouche, Yousra. "Caractérisation non linéaire de l'endommagement des matériaux composites par ondes guidées." Phd thesis, Université du Maine, 2013. http://tel.archives-ouvertes.fr/tel-00840424.
Повний текст джерелаNg, Po-king. "Molecular and polymeric metal complexes for electroluminescence applications." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20979435.
Повний текст джерелаPallon, Love. "Polyethylene/metal oxide nanocomposites for electrical insulation in future HVDC-cables : probing properties from nano to macro." Doctoral thesis, KTH, Polymera material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193591.
Повний текст джерелаNanokompositer av polyeten och metalloxidpartiklar anses vara möjliga material att använda i morgondagens isolationshölje till högspänningskablar för likström. För att nå en transmissionsspänning på 1 MV behövs isolationsmaterial som i jämförelse med dagens polyeten har lägre elektrisk ledningsförmåga, högre styrka mot elektriskt genomslag och som kan kontrollera ansamling av rymdladdningar. De senaste årens forskning har visat att kompositer av polyeten med nanopartiklar av metalloxider har potential att nå dessa egenskaper. I det här arbetet har kompositer av polyeten och nanopartiklar av MgO för elektrisk isolation producerats och karaktäriserats. Nanopartiklar av MgO har framställts från en vattenbaserad utfällning med efterföljande calcinering, vilket resulterade i polykristallina partiklar med en mycket stor specifik ytarea (167m2 g-1). MgO-nanopartiklarna ytmodifierades i n-heptan genom att kovalent binda oktyl(trietoxi)silan och oktadekyl(trimetoxi)silan till partiklarna för att skapa en hydrofob och skyddande yta. Extrudering av de ytmodifierade MgO nanopartiklarna tillsammans med polyeten resulterade i en utmärkt dispergering med jämnt fördelad partiklar i hela kompositen, vilket ska jämföras med de omodifierade partiklarna som till stor utsträckning bildade agglomerat i polymeren. Alla kompositer med låg fyllnadsgrad (1–3 vikt% MgO) visade upp till 100 gånger lägre elektrisk konduktivitet jämfört med värdet för ofylld polyeten. Vid högre koncentrationer av omodifierade MgO förbättrades inte de isolerande egenskaperna på grund av för stor andel agglomerat, medan kompositerna med de ytmodifierade fyllmedlen som var väl dispergerade behöll en kraftig reducerad elektrisk konduktivitet upp till 9 vikt% fyllnadshalt. Den minsta interaktionsradien för MgO-nanopartiklarna för att minska den elektriska konduktiviten i kompositerna fastställdes med bildanalys och simuleringar till ca 800 nm. Den teoretiskt beräknade interaktionsradien kompletterades med observation av en experimentell interaktionsradie genom att mäta laddningsfördelningen över en Al2O3-nanopartikle i en polyetenfilm med intermodulation (frekvens-mixning) elektrostatisk kraftmikroskop (ImEFM), vilket är en ny AFM-metod för att mäta ytpotentialer. Genom att lägga på en spänning på AFM-kantilevern kunde det visualiseras hur laddningar, både injicerades och extraherades, från nanopartiklarna men inte från polyeten. Det tolkades som att extra energinivåer skapades på och runt nanopartiklarna som fungerar för att fånga in laddningar, ekvivalent med den gängse tolkningen att nanopartiklar introducera extra elektronfällor i den polymera matrisen i nanokompositer. Nanotomografi användes för att avbilda elektriska träd i tre dimensioner. Avbildningen av det elektriska trädet visade att tillväxten av trädet hade skett genom bildning av håligheter framför den framväxande trädstrukturen. Håligheterna leder till försvagning av materialet framför det propagerande trädet och förenklar på det sättet fortsatt tillväxt. Bildningen av håligheter framför trädstrukturen uppvisar en analogi till propagering av sprickor vid mekanisk belastning, i enlighet med Griffiths koncept.
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Sahu, Laxmi Kumari D'Souza Nandika Anne. "Bulk and interfacial effects on density in polymer nanocomposites." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3619.
Повний текст джерела