To see the other types of publications on this topic, follow the link: Composite polymer particles.
Dissertations / Theses on the topic 'Composite polymer particles'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Composite polymer particles.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Winchester, Stuart. "Composite modification by preformed polymer particles." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267411.
Full text
2
Lu, Yan. "Polypyrrole-containing Composite Particles: Preparation, Characterization and Application." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1109235925474-80822.
Full textAbstract:
This research is focused on preparation of polypyrrole (PPy) composite particles by using socalled template oxidative polymerization method. As a template, water-soluble polymers, polymeric microgels, latex particles or bulk gels can be used. The morphology and properties of the composite particles can be controlled effectively by the proper use of the template. By choosing the dopant anion or oxidation agent it is possible to vary the conductivity of the polymer. In the case when uncrosslinked PVME was used as stabilizer, core-type polypyrrole spherical particles in the range of 50-100 nm were formed in both aqueous ethanol and water. Results of the elementary analysis, IR spectroscopy confirmed that the anionic salts can be incorporated in the PPy particles and play as the dopants. The presence of dopants in polypyrrole enhances the conductivity, especially in the case of sodium benzoate the conductivity of the final product has been improved by 3 orders. Polymeric microgels were also applied as the templates for polypyrrole deposition. When crosslinked PVME microgels were used in the oxidation polymerization of pyrrole, large PPy fibrils (appr. 400nm) were formed. Needle-like particles were formed due to the porous structure of microgels, which play a template role in the pyrrole polymerization process. When poly(VCL/AAEM) microgels were used as a template for oxidative polymerization of pyrrole, "raspberry-like" composite particles will be formed with PPy domains located in swollen hydropholic particle shell. Obtained stable composite microgels show similar thermal sensitivity as poly(VCL/AAEM) particles with fully reversible collapse-swelling properties. Increase of PPy content in composite particles increases conductivity of the composite material. The conductivity of composite particles prepared in water was much higher than that of prepared in water : ethanol mixtures. Furthermore, monodisperse PS-PEGMA particles, which were prepared in water medium by polymerization with sodium peroxydisulfate have been used as a template for deposition of polypyrrole (PPy). Obtained composite particles possess core-shell morphology where shell is composed out of small PPy nano-domains. The shell thickness can be varied by changing PPy load, controlling the overall template surface area in the system, and by influencing the pyrrole polymerization kinetics in presence of different oxidants. The last possibility provides also incorporation of different anions into polypyrrole shell. The stability of composite particles decreases gradually if the deposited PPy amount increases. It has been established that obtained particles are intrinsically coloured and the colour can be changed by the PS-PEGMA core size. Conductivity measurement shows that PS/PEGMA/PPy composite particles prepared by using phosphomolybdate as the oxidant are much more conductive than the particles prepared by the other two oxidants. The conductivity increases with the increase of PPy load in the system. Overall, the proper design of the template should give a possibility to control effectively the morphology, particle size and provide sufficient stability to the composite particles. Different morphologies, such as spherical, core-shell, raspberry and needle-like, with different particle size are expected to be available in different cases. By choosing the dopant anion or oxidation agent it is possible to vary the conductivity of the polymer. The stable water-based dispersions are expected to be used as additives for paint formulations, in electrorheology, microelectronic, ion-separation or disease diagnostics.
3
Wang, Nan. "Preparation and morphological study of composite nano-particles made of homopolymers." Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1374.
Full text
4
Lu, Yan. "Polypyrrole containing composite particles: preparation, characterization and application." Doctoral thesis, [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974241083.
Full text
5
Imberg, Anna. "On Phase Behaviours in Lipid/Polymer/Solvent/Water Systems and their Application for Formation of Lipid/Polymer Composite Particles." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributöt], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3795.
Full text
6
Otto, Christian [Verfasser], and Volker [Akademischer Betreuer] Abetz. "Electrically Conductive Composite Materials from Carbon Nanotube Decorated Polymer Powder Particles / Christian Otto ; Betreuer: Volker Abetz." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2017. http://d-nb.info/1150183748/34.
Full text
7
Stevanovic, Dejan, and dejan@mso anu edu au. "Delamination Properties of a Vinyl-Ester/Glass Fibre Composite Toughened by Particulate-Modified Interlayers." The Australian National University. Faculty of Engineering and Information Technology, 2002. http://thesis.anu.edu.au./public/adt-ANU20030421.212730.
Full textAbstract:
The main aim of this work is to examine fracture toughness improvement mechanisms of a
composite material containing tough interlayers modified with large thermoplastic
particles.
¶
Various vinyl-ester (VE)/ poly(acrylonitrile-butadiene-styrene) (ABS) blends were used
for the interlayer-toughening of a VE/glass fibre composite to increase delamination
resistance of the material under mode I and mode II loading. Dry ABS powder was mixed
with the liquid resin in four different weight ratios: 3.5, 7, 11 and 15 phr (parts per
hundred parts of resin) while the layer thickness was varied from 150 to 500um.
Firstly, the tensile and mode I fracture toughness properties of the VE/ABS blends were
assessed, and, by using the Raman Spectroscopy technique, a chemical reaction was
discovered which occurred during ABS/VE mixing. This reaction consisted of butadiene
dissolution from the ABS particles into the VE. Also, butadiene saturation within the VE
was achieved at a composition of around 7% ABS particle content. Both mode I and mode II
fracture toughness of the composite were significantly improved with the application of
interlayers. Mode I fracture toughness GIc was found to be a function of
interlayer thickness and ABS particle content variations, with the latter dominating
GIc after the saturation point. Mode II fracture toughness was found to be
independent of interlayer thickness and only moderately influenced by particle content.
The toughening mechanisms that were the most influential within this interlayered
material were plastic deformation and micro-cracking of the layer materials. Evidence of
both mechanisms was found using optical and scanning electron microscopy (SEM).
¶
A numerical analysis was conducted, using the experimental results from this study, to
further explain the basic toughening mechanisms and fracture behaviour in the materials.
The aim of the analysis was to examine the influence of the particles on the plastic zone
size that develops in front of the crack tip, and the interaction between the particles
and the crack tip. For this purpose FEA elastic-plastic crack propagation models were
employed. Good agreement with the experimental data was found.
8
Luo, Hongze. "Polymer/nano-organic composite proton exchange membranes for direct methanol fuel cell application." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
Full textAbstract:
The proton exchange membrane is one key component of direct methanol fuel cells, which has double functions of conducting protons, separating fuels and oxidant. At present, the performance and price of sulfonic acid proton exchange membrane used in direct methanol fuel cells are deeply concerned. In order to reduce membrane 's cost and improve performance of Nafion membrane, three different kinds of membranes have been studied in this thesis. These membranes are SPEEK membranes, SPEEK/ZP composite membranes and Nafion/ZP composite membranes.
9
Visaveliya, Nikunjkumar [Verfasser], Michael [Akademischer Betreuer] Köhler, Uwe [Akademischer Betreuer] Ritter, and Christophe [Akademischer Betreuer] Serra. "Microfluidic Synthesis and Assembly of Multi-Scale Polymer Composite Particles Towards Sensoric and Labeling Applications / Nikunjkumar Visaveliya. Betreuer: Michael Köhler. Gutachter: Uwe Ritter ; Christophe Serra." Ilmenau : Universitätsbibliothek Ilmenau, 2016. http://d-nb.info/1081935375/34.
Full text
10
Visaveliya, Nikunjkumar Verfasser], Michael [Akademischer Betreuer] [Köhler, Uwe [Akademischer Betreuer] Ritter, and Christophe [Akademischer Betreuer] Serra. "Microfluidic Synthesis and Assembly of Multi-Scale Polymer Composite Particles Towards Sensoric and Labeling Applications / Nikunjkumar Visaveliya. Betreuer: Michael Köhler. Gutachter: Uwe Ritter ; Christophe Serra." Ilmenau : Universitätsbibliothek Ilmenau, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2015000547.
Full text
11
Kanelidis, Ioannis [Verfasser]. "Polymer-Nanocrystal Composites: Copolymers, Polymeric Particles and Hybrid Systems / Ioannis Kanelidis." Wuppertal : Universitätsbibliothek Wuppertal, 2012. http://d-nb.info/1022590464/34.
Full text
12
Airaud, Cédric. "Couplage ROMP et ATRP en milieu dispersé aqueux : préparation et étude morphologique de particules polymères composites." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13698/document.
Full textAbstract:
Le confinement de polymères incompatibles au sein de particules induit une séparation de phase et conduit à la formation de morphologies particulières (cœur-écorce, hémisphérique…). Cette nanostructuration est à l’origine de propriétés de filmification particulières qui justifient l’utilisation des particules polymères composites dans le cadre d’applications comme la formulation de peintures ou de revêtements. Ce travail s’intéresse au développement d’approches permettant de préparer ces particules polymères composites en une seule étape et en milieu aqueux. La stratégie proposée repose sur le couplage « en simultané » de deux polymérisations distinctes: la polymérisation de cyclooléfines par métathèse (ROMP) et la polymérisation radicalaire par transfert d’atome (ATRP). Après avoir mis en évidence les difficultés liées au couplage de la ROMP et de l’ATRP en milieu dispersé aqueux, deux approches originales faisant intervenir respectivement des conditions de miniémulsion et de microémulsion sont proposées. Pour chacune d’elles, la présentation du principe de la synthèse et l’analyse de ses résultats précèdent l’étude morphologique des particules produitesSo as to broaden the scope of their applications in paints, coatings and impact-resistant plastics, many investigations have been dedicated to the preparation of nanostructured colloids over the past decades. Original morphologies including core-shell, hemispherical and complex occluded structures (raspberry-like, golf ball-like, octopus-like) can now be readily prepared. This work proposes a new straightforward one-pot, one-step, one-catalyst strategy to prepare polymer composite particles based on the simultaneous combination of two mechanistically distinct polymerizations in aqueous dispersed media. Norbornene (NB) and methyl methacrylate (MMA) were converted via Ring-Opening Metathesis Polymerization (ROMP) and Atom-Transfer Radical Polymerization (ATRP), respectively. Two original routes, designed to ensure simultaneous ROMP and ATRP, respectively under mini- and microemulsion conditions, are proposed. Both are successively reviewed on chemical and colloidal levels. Specific attention is paid to the morphologies of the prepared particles
13
Warner, Nathaniel A. "Investigation of the Effect of Particle Size and Particle Loading on Thermal Conductivity and Dielectric Strength of Thermoset Polymers." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849629/.
Full textAbstract:
Semiconductor die attach materials for high voltage, high reliability analog devices require high thermal conductivity and retention of dielectric strength. A comparative study of effective thermal conductivity and dielectric strength of selected thermoset/ceramic composites was conducted to determine the effect of ceramic particle size and ceramic particle loading on thermoset polymers. The polymer chosen for this study is bismaleimide, a common aerospace material chosen for its strength and thermal stability. The reinforcing material chosen for this study is a ceramic, hexagonal boron nitride. Thermal conductivity and dielectric breakdown strength are measured in low and high concentrations of hexagonal boron nitride. Adhesive fracture toughness of the composite is evaluated on copper to determine the composite’s adhesive qualities. SEM imaging of composite cross-sections is used to visualize particle orientation within the matrix. Micro-indentation is used to measure mechanical properties of the composites which display increased mechanical performance in loading beyond the percolation threshold of the material. Thermal conductivity of the base polymer increases by a factor of 50 in 80%wt loading of 50µm hBN accompanied by a 10% increase in composite dielectric strength. A relationship between particle size and effective thermal conductivity is established through comparison of experimental data with an empirical model of effective thermal conductivity of composite materials.
14
Eroglu, Esra. "Synthesis And Characterization Of New Conducting Polymer- Nano Particle Composites." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615631/index.pdf.
Full textAbstract:
In this study, conjugated monomers containing fluorene units2-(9,9-dihexyl-2-(thiophen-2-yl)-9H-fluoren-7-yl)thiophene (TFT) and 5-(9,9-dihexyl-2-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-fluoren-7-yl)-2,3dihydrothieno[3,4b ][1,4] dioxine (EFE) were synthesized on the basis of donor-acceptor-donor approach and their electrochemical polymerization were achieved via potential cycling. Optical and electrochemical properties of their corresponding polymers, poly(2-(9,9-dihexyl-2-(thiophen-2-yl)-9H-fluoren-7-yl)thiophene) PTFT, and poly(5-(9,9-dihexyl-2-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-fluoren-7-yl)-2,3dihydrothieno[3,4b ][1,4] dioxine) PEFE, were investigated and it was found that polymer films exhibited quasi-reversible redox behavior (Epox= 1.10 V for PTFT, Epox = 0.70 V and 1.00 V for PEFE) accompanied with a reversible electrochromic behavior, yellow to dark green for PTFT, yellow to parliament blue for PEFE. Their band gap values (Eg) were found to be 2.36 eV and 2.26 eV for PTFT and PEFE, respectively. Furthermore, gold nanoparticles (AuNP) were prepared and their interaction with polymer films, PTFT and PEFE, were investigated using spectroscopic techniques. The fluorescence properties of the polymers and their composites, prepared by the interaction of AuNP with polymers, were also investigated.
15
Liu, Jing. "Carbon nanotube/polymer composites and novel micro- and nano-structured electrospun polymer materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22673.
Full textAbstract:
Thesis (Ph. D.)--Textile and Fiber Engineering, Georgia Institute of Technology, 2007.Committee Chair: Kumar, Satish; Committee Member: Carr, Wallace; Committee Member: Graham, Samuel; Committee Member: Griffin, Anselm; Committee Member: Yao, Donggang.
16
Rivière, Lisa. "Analyse des mécanismes de conduction thermique dans les composites structuraux PEEK/particules submicroniques d'argent." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30200/document.
Full textAbstract:
Ce travail s'inscrit dans la problématique de l'optimisation des transferts thermiques et électriques dans les composites à matrice polymère. Il a été démontré que l'introduction de particules conductrices dans une matrice isolante permet d'en augmenter la conductivité thermique. À l'échelle macroscopique, les mécanismes résistifs sont influencés par un jeu complexe de paramètres : nature des constituants, morphologie de la phase dispersée et interactions entre matrice et particules. L'influence de ces différents paramètres sur les propriétés thermiques de composites PEEK/particules d'argent submicroniques a été analysée. Les données expérimentales ont été comparées à des modèles afin d'interpréter l'origine structurale de l'évolution de la conductivité thermique observée. L'approche complète des mécanismes de conduction thermique implique l'analyse des composantes capacitive et diffusive. La capacité calorifique, la diffusivité thermique et la conductivité thermique sont liées aux échelles microscopiques et macroscopiques. Ces propriétés ont été étudiées en fonction du taux de particules et de la températureThis work deals with the optimization of thermal transport mechanisms in polymer-based composites. It has been demonstrated that the introduction of conductive particles in a polymer matrix contributes to thermal conductivity enhancement. At macroscopic scale, resistive mechanisms are ruled by a complex set of parameters: constituents' nature, dispersed phase morphology and matrix/particles interactions. The influence of these parameters on PEEK/silver submicron particles composites has been studied. Experimental data have been compared to models to analyse the structural origin of thermal conductivity evolution. A global approach to study heat transport mechanisms imply the multiscale understanding of capacitive and diffusive contributions. Heat capacity, thermal diffusivity and thermal conductivity have been studied as a function of particles content and temperature
17
Yang, Jingting. "Carbon Nanotubes Reinforced Composites for Wind Turbine Blades." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1315410407.
Full text
18
Keum, Dong-ki. "Organic-inorganic composites of CaCO3 particles by organic polymer templates." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147661.
Full text
19
Lye, J. E. "A study of the internal particle morphology of composite polymer latices." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381426.
Full text
20
Tenery, Daeri. "IMAGING AND SPECTROSCOPY OF CONDUCTING POLYMER-FULLERENE COMPOSITE MATERIALS." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3241.
Full textAbstract:
Since the development and optical study of conjugated (conducting) polymers it has become apparent that chain conformation and aggregation at the molecular scale result in complex heterogeneous nanostructured bulk materials for which a detailed insight into morphological, spectroscopic as well as optoelectronic properties and mechanisms is overwhelmingly difficult to obtain. Nanoparticles composed of the conjugated polymer poly (MEH-PPV) and nanocomposite nanoparticles consisting of MEH-PPV doped with 1-(3-methoxycarbonylpropyl)-1-phenyl-C61 (PCBM) were prepared as model systems to study these materials at the length scale of one to a few domains. The MEH-PPV and PCBM doped nanoparticles were analyzed by single imaging/particle spectroscopy (SPS) and revealed molecular scale information on the structure-property relationships of these composite materials. The data obtained from SPS were investigated in terms of spectral difference between doped and undoped nanoparticles. The doped nanoparticles are blue shifted by approximately 5-10 nm, have an additional blue shoulder, and show different vibronic structure than the undoped nanoparticles. Specifically, relative intensity of the 0-1 transition is lower than for the undoped nanoparticles. These data are indicative of differences in molecular order between both nanoparticle systems, detected at the molecular scale. In addition, the effect of electrical fields present in devices on the interfacial charge transfer properties was evaluated. Furthermore, these nanoparticles were incorporated into the lipid nanotubes to study the diffusion process of the single MEH-PPV nanoparticles inside the lipid nanotubes. Our data shows a clear proof of concept that diffusion of nanoparticles inside the hollow lipid nanotubes can be studied on a single particle basis, which will allow us to study diffusion processes quantitatively and mechanistically within the framework of developing a biocompatible drug and gene delivery platform.Ph.D.
Department of Chemistry
Sciences
Chemistry PhD
21
Leng, Tianyang. "Cellulose Nanocrystals: Particle Size Distribution and Dispersion in Polymer Composites." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/34073.
Full textAbstract:
This thesis describes the characterization of the particle size distribution of cellulose nanocrystals (CNC), the synthesis and characterization of fluorescent CNCs, and the development of a fluorescence microscopy method to probe the distribution of fluorescent CNCs in polymer composites.
In this thesis, several methods are used to characterize the size of CNC particles. Size distribution measurements by single particle counting methods (Transmission electron microscopy, Atomic force microscopy) are compared to an ensemble method, Dynamic lighting scattering (DLS) and differences between the various methods will be discussed. The effect of sonication on the CNC size distributions measured by AFM and DLS is examined. Furthermore, a reliable and reproducible method for re-dispersing dry CNC powder will be explored in this chapter since CNC is often stored in a dry environment due to its stability. Rhodamine B isothiocyanate (RBITC) and 5-(4,6-dichlorotriazinyl) amino fluorescein (DTAF) were selected for labelling CNCs. These dyes have the advantage of being cheap and readily available and compatible with relatively simple synthetic chemistry. The photophysical properties of all dye labeled CNCs were studied in more detail than in previous studies. The focus is on understanding the most appropriate labeling efficiency to maximize the ability to detect individual CNCs while minimizing the amount of dye used to avoid modifying the CNC properties. The characterization methods include ensemble methods such as UV-Vis absorption and scattering measurements, fluorescence spectroscopy and single molecule methods such as Total internal reflection fluorescence microscopy (TIRFM), Atomic force microscopy (AFM) and correlated TIRFM/AFM measurements. All of these methods have their advantages and disadvantages. After characterization, the most suitable dye labeled CNC sample was selected for development of a fluorescence microscopy method to characterize CNC distribution in CNC/polymer composites. The dye labeled CNC has been incorporated into polyvinyl alcohol (PVA) films and studied by fluorescence microscopy. These experiments demonstrated that the level of CNC agglomeration varies significantly for different film preparation methods, indicating that fluorescence microscopy is a useful and easily accessible method for optimizing film preparation. The self-quenching of the dye in the film was also measured and discussed and is an important consideration for choice of the dye loading and CNC content in the films.
22
Barkoula, Nektaria-Marianthi [Verfasser], and Jósef [Akademischer Betreuer] Karger-Kocsis. "Solid Particle Erosion Behaviour of Polymers and Polymeric Composites / Nektaria-Marianthi Barkoula ; Betreuer: Jósef Karger-Kocsis." Kaiserslautern : Technische Universität Kaiserslautern, 2019. http://d-nb.info/1184879818/34.
Full text
23
Aronow, Roger Lockwood. "Toughening mechanisms in composites of miscible polymer blends with rigid filler particles." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35520.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.Vita.
Includes bibliographical references (leaves 97-98).
Fillers are often added to polymers improve stiffness at the cost of reduced toughness, but this tradeoff is not universal. Well-dispersed microscopic particles have been shown to improve toughness and stiffness simultaneously in some cases. The effect depends on interparticle distance as well as interfacial adhesion. This type of toughening has been more successful in semicrystalline than in amorphous systems. An amorphous polymer blend was chosen to elucidate the effect of matrix properties on the toughening mechanism. The ternary blend of PMMA, PVC, and DOP (a common plasticizer) was characterized using TEM, and was found to be miscible over much of the PVC-rich domain. The blend Tg's fit well to an empirical model, which was used to predict a constant-Tg ([approx.] 40°C) blend series. Mechanical testing showed a wide, systematic variation in properties among these blends, although all were brittle in tension. The blend 90% PVC / 10% DOP was mixed with barium sulfate filler and evaluated for toughness in slow tension. In general, the composites showed decreasing toughness with increasing filler content. However, several specimens at 5 vol% filler exhibited a large increase in ductility and toughness ([approx.] 19-fold).
(cont.) SEM examination of tough specimens revealed several important findings: (1) Filler is present both as micron-scale agglomerates and as well dispersed particles. (2) Well-dispersed particles remain bonded to the matrix even for large deformations. (3) Filler agglomerates are prone to debonding and internal fracture, creating void space and enabling deformation. Base blend properties significantly affect the response to filler. The blend 8% PMMA / 80% PVC / 12% DOP showed small increases in ductility for 5 and 10 vol% filler, with the best result being a 10 vol% specimen showing a 6-fold toughness increase over the neat-blend average. This specimen showed similar microscopic behavior to the 90/10 blend, i.e. agglomerate debonding and fracture, but to a lesser degree. The blend 16% PMMA / 70% PVC / 14% DOP, showed no significant toughening. Also investigated were high-Tg ([approx.] 70°C) blends, which were brittle and became weaker with filler, and low-Tg ([approx.] 30°C) blends, which were intrinsically ductile and were not toughened by filler.
by Roger Lockwood Aronow.
Ph.D.
24
Zhu, Yingdan. "Characterisation of Particle Dispersion in Different Polymeric Composite Systems." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520225.
Full text
25
Woods, Courtney G. "Role of nano-particles on crystalline orientation in polypropylene/clay nanocomposite films." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180242/unrestricted/woods%5Fcourtney%5Fg%5F200312%5Fms.pdf.
Full text
26
Davis, James William. "Development of a Laponite Pluronic Composite for Foaming Applications." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc271798/.
Full textAbstract:
The focus of the following research was to provide an optimized particle stabilized foam of Laponite and Pluronic L62 in water by understanding (1) the Laponite-Pluronic interactions and properties for improved performance in a particle stabilized foam and (2) the interfacial properties between air and the Laponite-Pluronic complex. These studies were conducted using both bulk and interfacial rheology, XRD, sessile droplet, TGA and UV-vis. Two novel and simple techniques, lamella break point and capillary breakup extensional rheometry, were used to both understand the Laponite Pluronic L62 interaction and determine a different mechanism for foaming properties. Bulk rheological properties identified an optimal Laponite concentration of 2% with Pluronic L62 ranging from 2.5% and 6.5%, due to the ease of flow for the dispersion. The Pluronic L62 was observed to enhance the Laponite bulk rheological properties in solution. Additionally TGA showed a similar trend in thermal resistance to water with both addition of Laponite and Pluronic L62. XRD demonstrated that 0.25% Pluronic intercalated into Laponite from dried 2% Laponite films. XRD demonstrated that the Laponite matrix was saturated at 1% Pluronic L62. UV-vis demonstrated that a monolayer of Pluronic L62 is observed up to 0.65% Pluronic L62 onto Laponite. Interfacial rheology showed that Laponite enhances Pluronic L62 at the air-liquid interface by improving the storage modulus as low at 0.65% Pluronic L62 with 2% Laponite. The lamella breakpoint of Laponite with Pluronic films indicate strong film interaction due to higher increases in mass. Extensional rheology indicates that 2.5% to 6.5% Pluronic with 2% Laponite show the most filament resistance to stretching.
27
Elmkharram, Hesham Moh A. "Mechanically Processed Alumina Reinforced Ultra-high Molecular Weight Polyethylene (UHMWPE) Matrix Composites." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/31522.
Full textAbstract:
Alumina particles filled Ultra-high Molecular Weight Polyethylene (UHMWPE), with Al2O3 contents 0, 1, and 2.5 wt% were milled for up to 10 hours by the mechanical alloying (MA) process performed at room temperature to produce composite powders. Compression molding was utilized to produce sheets out of the milled powders. A partial phase transformation from orthorhombic and amorphous phases to monoclinic phase was observed to occur for both the un-reinforced and reinforced UHMWPE in the solid state, which disappeared after using compression molding to produce composite sheets. The volume fraction of the monoclinic phase increased with milling time, mostly at the expense of the amorphous phase. The melting temperature decreased as a function of milling time as a result of modifications in the UHMWPE molecular structure caused by the milling. At the same time, for a given alumina composition the activation energy of melting increased with milling time. Generally, the crystallinity of the molded sheets increased with milling time, and this caused the yield strength and elastic modulus to increase with milling time for a given alumina composition. However, the tensile strength and ductility remained about the same.Master of Science
28
Peng, Peng. "PREPARATION AND CHARACTERIZATION OF POLYMER/FERROELECTRIC CERAMIC PARTICLE COMPOSITES FOR ELECTROACTIVE ACTUATION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1443539252.
Full text
29
Roosz, Nicolas. "Elaboration de particules composites silice-polyaniline en vue d'applications environnementales." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD083/document.
Full textAbstract:
Les matériaux hybrides organique/inorganiques ont reçu beaucoup d'attention ces dernières années dans les études des nanomatériaux. En effet, ils possèdent des propriétés physiques et chimiques uniques grâce aux effets synergiques de chaque composant. En particulier, les nanoparticules de silice (SiO2) présentent des caractéristiques intéressantes, comme une bonne stabilité chimique et thermique. Elles peuvent être préparées de différentes tailles et peuvent aussi être facilement fonctionnalisées. Les polymères conducteurs intrinsèques comme le polythiophène et la polyaniline (PANI) peuvent exister sous différents états d'oxydation et donc répondre à des stimuli extérieurs en changeant une de leur caractéristique (couleur, conductivité, etc…). La PANI est un polymère non-toxique, thermiquement stable et peu coûteux avec une conductivité relativement élevée qui a été utilisée comme film antistatique, matériel d'électrode, inhibiteur de corrosion et comme surface sensible de capteur. Depuis la découverte des polymères conducteurs en 1977, plusieurs travaux ont été effectués sur la préparation, la caractérisation et les applications de films polymériques construits à la surface de matériaux comme la silice. Parmi les différents types de composites existants, les particules de type cœur@coquille composées d’un cœur inorganique et d’une couronne de polymère sont les plus prometteurs. Dans cette étude, nous avons donc décidé de travailler sur la synthèse de composites cœur@coquille constitués d’une coquille de PANI et d’un cœur de particules de silice.Dans la littérature, en utilisant des protocoles expérimentaux similaires, deux morphologies très contradictoires ont été obtenues après la polymérisation par oxydation chimique d'aniline en présence de particules de silice : cœur@coquille et framboise (structure inversée avec la PANI comme cœur). Nous avons alors décidé de réexaminer la synthèse de PANI en présence de particules de silice. Pour cela, nous avons, dans un premier temps, synthétisé des particules de silice monodisperses de différentes tailles (300, 160 et 90 nm) par procédé Stöber. Nous avons ensuite réalisé la polymérisation chimique de l'aniline en présence de ces particules de silice dans des conditions contrôlées afin de promouvoir une adsorption des ions aniliniums en surface des particules. Différents paramètres expérimentaux ont été étudiés tels que la température, la concentration en réactifs, la taille des particules… Les résultats en termes de morphologie sont discutés en fonction de ces paramètres. Dans un second temps, nous avons fonctionnalisé la surface des particules de silice par un alcoxysilane afin de favoriser la polymérisation de l’aniline à la surface des particules. Ainsi, nous avons obtenu des structures SiO2@PANI avec une épaisseur de polymère contrôlable. La dernière partie de ce travail traite des premiers essais qui ont été réalisés afin d’utiliser ces composites SiO2@PANi pour des applications environnementales. Deux applications ont notamment été envisagées, l'adsorption de métaux pour l'aspect de particule et la détection de gaz pour les capacités conductrices de la PANIOrganic/inorganic hybrid materials have received much attention in recent years such as in the field of nano-materials. Indeed, these materials possess unique physical and chemical properties due to the synergistic effect of both components. In particular, silica nanoparticles (SiO2) present interesting properties, such as good chemical and thermal stabilities. They can be prepared in different size and can be easily chemically modified. Intrinsically conducting polymers such as polythiophene and polyaniline (PANI) can exist in different oxidation states and respond to external stimuli by changing one of their characteristics (color, conductivity, …). PANI is a non-toxic, thermally stable and low cost polymer with relatively high conductivity that has been used as antistatic coating, electrode materials, corrosion inhibitor and active layer of sensors. Since the discovery of conducting polymer in 1977, several works have been carried out on the preparation, characterization and applications of polymeric films build on various surfaces like silica. Among the different kinds of composites that exist, inorganic-polymer core-shell nanoparticles are more promising candidates. In this study, we decided to work on the synthesis of core@shell hybrid compounds based on PANI shells and silica nanoparticles cores.In the literature, using similar experimental protocols, two morphologies have been obtained after chemical polymerization of aniline in the presence of silica particles: core@shell and raspberry (inverted structure with PANI as core). We thus decided to reinvestigate the synthesis of PANI in the presence of silica particles. For this, we first synthesized silica particles with different sizes by Stöber process. We then performed the chemical polymerization of aniline in the presence of these naked silica particles under different conditions: temperature, concentration of reactive. However, in all cases, we never managed to obtain core@shell structures. Finally, we succeed in developing a method to prepare these core@shell particles which relies on the functionalization of the SiO2 by alkoxysilanes followed by the polymerization of aniline at room temperature. A series of core-shell particles with tunable PANI thickness has been prepared by this method. The last part of this work deals with the first tests that have been carried out in order to use these composites SiO2@PANi for environmental applications. Two applications have been considered, the adsorption of metals for the particle appearance and the detection of gas for the conductive capacities of the PANI
30
Tsai, Liren. "SHOCK WAVE STRUCTURE AND SPALL STRENGTH OF LAYERED HETEROGENEOUS GLASS/POLYMER COMPOSITE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1138377998.
Full text
31
Gentieu, Timothée. "Development of filled polymers for the replacement of ceramics used as ballistic protection layer." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0419.
Full textAbstract:
Les matériaux céramiques présentent généralement des propriétés mécaniques très intéressantes pour la réalisation de blindages. Ce sont des matériaux très durs et pourtant légers. Les plaques de blindages en céramique sont classiquement mises en forme par pressage à haute température de poudres, ce qui limite la taille et la forme des réalisations tout en impliquant un coût élevé. Une alternative pour produire ces pièces est le moulage d’un composite constitué de particules de céramiques dans une matrice époxy. Ce procédé permet de réduire le coût des pièces tout en autorisant des géométries plus complexes et des dimensions plus importantes.Le comportement mécanique de ce type de matériau dépend de multiples paramètres de conception : propriétés mécaniques des constituants (matrice polymère et particules céramiques), proportion volumique des deux phases, taille et distribution spatiale des particules ou encore l’adhésion entre les constituants. L’objectif de la thèse est d’évaluer l’influence de ces paramètres sur les propriétés d’usage du matériau. Pour ce faire, une analyse multi-échelle du matériau sous sollicitations quasi-statique et dynamique est réalisée.Plus précisément, les propriétés statiques et dynamiques du composite à renforts particulaires ont été déterminées pour différentes combinaisons de ces paramètres de conception. En particulier, le mécanisme de décohésion particule/matrice a été spécifiquement étudié. Les approches de Modèles de Zone Cohésive (CZM) et de Mécanique de la Rupture Finie (FFM) ont été utilisées pour modéliser ce phénomène et un fort effet de taille des particules a été observéCeramics have extensively been used for ballistic protection in the last decades. The combination of their mechanical properties makes them very interesting for armouring. Indeed, they exhibit a high hardness, large compression strength, high stiffness and low density. Ceramic armouring plates are commonly manufactured through a sintering process, where ceramic powders are pressed at high temperatures. This manufacturing process tends to limit the size and shape of components and imparts high costs. On the other hand, moulding using a polymer matrix composite provides an alternative process for developing lower cost parts whilst accommodating increased complexity of geometry and size.However, the mechanical behaviour of such a material is not completely known and depends on multiple design parameters: the mechanical properties of the phases, their volume fraction, the size and spatial distributions of the particles, and the adhesion between the components. The objective of the thesis is to evaluate the influence of the main morphological parameters on the overall mechanical properties, emphasising the influence of the particle/matrix adhesion. To do so, both numerical and experimental multiscale analyses of the material under quasi-static and dynamic loadings were carried out.More precisely, static and dynamic properties of the particle-reinforced composite have been determined for different combinations of the design variables. In particular, attention has been dedicated to the particle/matrix decohesion mechanism. Cohesive zone models (CZM) and Finite Fracture Mechanics (FFM) approaches were used to model this phenomenon and a strong effect of the particle size on debonding was observed
32
Huang, Shu-Chen. "Controlled mineralization of organic-inorganic calcium carbonate composite particles by use of water-soluble polymers." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136308.
Full text
33
Alfinaikh, Reem. "Preparation and Characterization of Poly(Ethylene Oxide)(MW 35K and 100K)/ Silica Nanoparticle Composites." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2017. http://digitalcommons.auctr.edu/cauetds/109.
Full textAbstract:
In recent years, polymer-inorganic nanoparticle compositions have been a subject of considerable interest in order to achieve desired chemical, physical properties and mechanical properties. In this study a polymer nanocomposites have been prepared by incorporating silica nanoparticles (~20 nm) as fillers into poly(ethylene oxide) matrix. The composites of poly(ethylene oxide) and silica nanoparticles were prepared by solution blending. The product composites were powders. The thermal properties of the composites were investigated using the Differential Scanning Calorimetry. The Nuclear Magnetic Resonance (13C solid state, T1ρ), Atomic Force Microscopy, X-ray diffraction and Fourier Transform Infrared Spectroscopy were used to investigate the effect of the nanoparticles on the polymer matrix. The results suggest that the silica nanoparticles were reasonably well dispersed in the PEO 35K. The dispersion was accompanied by slightly reduced the crystallinity. However, with increasing the SiO2 nanoparticles the aggregation Phenomenon appears. Moreover, with increase in the MW of the PEO to 100K the dispersion of the nanoparticles decreased and aggregation phenomenon is observed even at lower of SiO2 contents.
34
Seifert, Julian [Verfasser]. "Particle-Matrix Interactions in Hybrid Magnetic Polymer Composites with Varying Network Architecture / Julian Seifert." München : Verlag Dr. Hut, 2021. http://d-nb.info/1240540116/34.
Full text
35
MURUGESAN, SURESH. "IN SITU PREPARATION AND STRUCTURE - PROPERTY STUDIES OF FILLER PARTICLES IN POLY(DIMETHYLSILOXANE) ELASTOMERS." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1059393661.
Full text
36
Paydavosi, Sarah. "Study of organic molecules and nano-particle/polymer composites for flash memory and switch applications." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75644.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 205-218).
Organic materials exhibit fascinating optical and electronic properties which motivate their hybridization with traditional silicon-based electronics in order to achieve novel functionalities and address scaling challenges of these devices. The application of organic molecules and nano-particle/polymer composites for flash memory and switch applications is studied in this dissertation. Facilitating data storage on individual small molecules as the approach the limits in miniaturization for ultra-high density and low power consumption media may enable orders of magnitude increase in data storage capabilities. A floating gate consisting of a thin film of molecules would provide the advantage of a uniform set of identical nano-structured charge storage elements with high molecular area densities which can result in a several-fold higher density of charge-storage sites as compared to quantum dot (QD) memory and even SONOS devices. Additionally, the discrete charge storage in such nano-segmented floating gate designs limits the impact of any tunnel oxide defects to the charge stored in the proximity of the defect site. The charge retention properties of molecular films was investigated in this dissertation by injecting charges via a biased conductive atomic force microscopy (AFM) tip into molecules comprising the thin films. The Kelvin force microscopy (KFM) results revealed minimal changes in the spatial extent of the charge trapping over time after initial injection. Fabricated memory capacitors show a device durability over 105 program/erase cycles and hysteresis window of up to 12.8 V, corresponding to stored charge densities as high as 5.4x 1013 cm-2, suggesting the potential use of organic molecules in high storage capacity memory cells. Also, these results demonstrate that charge storage properties of the molecular trapping layer can be engineered by rearranging molecules and their a-orbital overlaps via addition of dopant molecules. Finally, the design, fabrication, testing and evaluation of a MEMS switch that employs viscoelastic organic polymers doped with nano-particles as the active material is presented in this dissertation. The conductivity of the nano-composite changes 10,000-fold as it is mechanically compressed. In this demonstration the compressive squeeze is applied with electric actuation. Since squeezing initiates the switching behavior, the device is referred to as a "squitch". The squitch is essentially a new type of FET that is compatible with large area processing with printing or photolithography, on rigid or flexible substrates and can exhibit large on-to-off conduction ratio.
by Sarah Paydavosi.
Ph.D.
37
Zhang, Rui. "Polymeric Complexes and Composites for Aerospace and Biomedical Applications." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96565.
Full textAbstract:
Polymers, among metals and ceramics, are major solid materials which are widely used in all kinds of applications. Polymers are of particular interest because they can be tailored with desirable properties. Polymer-based complexes and composites, which contain both the polymers and other components such as metal oxide/salts, are playing a more and more important role in the material fields. Such complexes and composites may display the benefits of both the polymer and other materials, endowing them with excellent functionalities for targeted applications.
In this dissertation, a great deal of research was conducted to synthesize novel polymers and build polymeric complexes and composites for biomedical and aerospace applications. In chapter 3, two methods were developed and optimized to fabricate sub-micron high-performance polymer particles which were subsequently used to coat onto functional carbon fibers via electrostatic interactions, for the purpose of fabricating carbon fiber reinforced polymer composites. In chapter 4, a novel Pluronic® P85-bearing penta-block copolymer was synthesized and formed complexes with magnetite. The complexes displayed non-toxicity to cells normally but were able to selectively kill cancer cells without killing normal cells when subjected to a low-frequency alternating current magnetic field. Such results demonstrated the potential of such polymeric complexes in cancer treatment. Chapter 5 described the synthesis of several ionic graft copolymers primarily bisphosphonate-containing polymers, and the fabrication of polymer-magnetite complexes. The in-depth investigation results indicated the capability of the complexes for potential drug delivery, imaging, and other biomedical applications. Chapter 6 described additional polymer synthesis and particle or complex fabrication for potential drug delivery and imaging, as well as radiation shielding.PHD
38
Cenacchi, Pereira Ana Maria. "Synthèse de particules composites anisotropes polymère / inorganique par polymérisation RAFT en émulsion." Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01067453.
Full textAbstract:
Ces travaux décrivent l'élaboration de latex hybrides de polymère / nanotubes d'Imogolite et polymère / nanofeuillets d'hydroxydes doubles lamellaires (HDL) en milieu aqueux dispersé. Les deux charges inorganiques ont été choisies pour leurs propriétés thermiques, mécaniques et pour leur anisotropie de forme, ce qui pourrait permettre l'élaboration de films nanostructurés. Les latex ont été synthétisés par une stratégie originale basée sur le procédé de polymérisation RAFT en émulsion. Cette stratégie consiste à utiliser des copolymères hydrophiles (macroRAFT), comportant à la fois des unités d'acide acrylique et un groupe trithiocarbonate terminal, comme agents de couplage et stabilisants. Dans un premier temps, ces macroRAFTs ont été adsorbés à la surface des nanoparticules inorganiques, puis l'extension de ces chaînes a été réalisée par la polymérisation d'un monomère hydrophobe selon un procédé semi-batch. Des nanotubes d'Imogolite décorés de particules de latex ou des nanotubes d'Imogolite encapsulés ont été obtenus, selon les conditions de synthèse adoptées. L'effet de différents paramètres sur la morphologie finale des particules hybrides a été étudié. La nature de l'agent macroRAFT s'est avérée être un paramètre clé pour le succès de l'encapsulation. La même stratégie a été utilisée en vue de l'encapsulation des HDL. Quelles que soient les conditions investiguées, des latex stables contenant des particules d'HDL encapsulées par du polymère ont été formés. Dans tous les cas, la morphologie des latex nanocomposites a été caractérisée par MET et cryo-MET et reliée à la méthode de modification de la surface et aux conditions de polymérisation. Enfin, les propriétés mécaniques ainsi que la microstructure des films hybrides de polymère / nanotubes d'Imogolite ont été étudiées par DMA et MET, respectivement, et reliées à la morphologie des particules de latex
39
Su, Ruo Qing. "New composite material based on silsesquioxane polymers and nanoporous particles for low-k [low-kappa] dielectric application." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972240519.
Full text
40
Chen, Jing. "Toughening epoxy polymers and carbon fibre composites with core-shell particles, block copolymers and silica nanoparticles." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14261.
Full textAbstract:
Epoxies are a class of high-performance thermosetting polymers which have been widely used in many industrial applications. However, unmodified epoxies are susceptible to brittle fracture due to their highly crosslinked structure. As a result, epoxies are normally toughened to ensure the feasibility of these materials for practical applications. Recently, a new generation of toughening agents such as polysiloxane based core-shell rubber (CSR) particles, amphiphilic block copolymers and silica nanoparticles have been developed to toughen epoxies. These new toughening agents will be studied in this thesis to pursue ultra-tough and stiff epoxies without compromising other desirable properties. Polysiloxane based CSR particles were able to toughen an anhydride cured epoxy over a wide range of temperatures from -109 °C to 20 °C. At -109 °C, the fracture energy of the epoxy could still be increased from 174 to 481 J/m2 with the addition of 20 wt% of the CSR particles. The toughening mechanisms of these CSR particle modified epoxies were identified as shear band yielding and plastic void growth. A series of commercial poly(methyl methacrylate)-b-poly(butylacrylate)-b-poly( methyl methacrylate) (MAM) triblock copolymers were studied as toughening agents in two epoxy systems. The fracture toughness was generally increased by these block copolymers, although their toughening performance was dependent on the crosslink density of the epoxies and the morphologies of the modified epoxies. The MAM modified epoxies were also studied as the matrix materials in fibre-reinforced composites to investigate the transfer of toughness from the matrix materials to the composites. Full (1 to 1) and nearly full toughness transfer was obtained for the composites. Hybrid toughening using a combination of the MAM block copolymer and silica nanoparticles has also been investigated in the same epoxy systems. The addition of the silica nanoparticles further increased the toughness of the MAM modified epoxies if micron-sized MAM particles present.
41
Yeh, Hsi-wei. "Investigation of Polymeric Composites for Controlled Drug Release." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4971.
Full textAbstract:
The Electrospray (ES) technique is a promising particle generation method for drug delivery due to its capabilities of producing monodisperse PLGA composite particles with unique configurations and high drug encapsulation efficiency. In the dissertation work, the coaxial dual capillary ES was used to generate drug-loaded core-shell PLGA particles to study the effects of particle filling materials, drug loading locations and particle shell thicknesses on the resultant in vitro release behaviors of the hydrophilic and/ or hydrophobic model drugs. Through release profile characterization of drug-loaded PLGA particles (particle size: 400 nm and 1 μm), it was confirmed that the co-encapsulation of Budesonide (BUD, the hydrophobic small-molecule model drug) and Theophylline (THY, the hydrophilic small-molecule model drug) in the particle cores is the most effective drug loading strategy for extended release of the fixed combined BUD and THY. Particles composed of PLGA fillers with lower molecular weights and with greater shell layer thicknesses could release THY in a well controlled fashion. On the other hand, a slower release rate of Bovine Serum Albumin (BSA, the protein model drug) from PLGA particles with greater shell thickness was also observed. Sequential release of BSA and Paclitaxel (PTX, the hydrophobic small-molecule anti-cancer model drug) was achieved by the 400-nm PLGA (Mw: 7,000-17,000 g/mol, LA/GA: 50/50) particles with potential biopharmaceutical applications in cancer therapy.
42
Bonner, Maxwell Scotland. "Characterization of composite broad band absorbing conjugated polymer nanoparticles using steady-state, time-resolve and single particle spectroscopy." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4741.
Full textAbstract:
As the global economy searches for reliable, inexpensive and environmentally friendly renewable energy resources, energy conservation by means of photovoltaics has seen near exponential growth in the last decade. Compared to state-of-the-art inorganic solar cells, organic photovoltaics (OPVs) composed of conjugated polymers are particularly interesting because of their processability, flexibility and the potential for large area devices at a reduced fabrication cost. It has been extensively documented that the interchain and intrachain interactions of conjugated polymers complicate the fundamental understanding of the optical and electronic properties in the solid-state (i.e. thin film active layer). These interactions are highly dependent on the nanoscale morphology of the solid-state material, leading to a heterogeneous morphology where individual conjugated polymer molecules obtain a variety of different optoelectronic properties. Therefore, it is of the utmost importance to fundamentally study conjugated polymer systems at the single molecule or nanoparticle level instead of the complex macroscopic bulk level.This dissertation research aims to develop simplified nanoparticle models that are representation of the nanodomains found in the solid-state material, while fundamentally addressing light harvesting, energy transfer and interfacial charge transfer mechanisms and their relationship to the electronic structure, material composition and morphology of the nanoparticle system. In preceding work, monofunctional doped nanoparticles (polymer-polymer) were fabricated with enhanced light harvesting and Forster energy transfer properties by blending Poly((o-phenylenevinylene)-alt-(2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene)) (BPPV) and Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) at various MEH-PPV doping ratios.; While single particle spectroscopy (SPS) reveals a broad distribution of optoelectronic and photophysical properties, time-correlated single photon counting (TC-SPC) spectroscopy displays multiple fluorescence lifetime components for each nanoparticle composition, resulting from changing polymer chain morphologies and polymer-polymer aggregation. In addition, difunctional doped nanoparticles were fabricated by doping the monofunctional doped nanoparticles with PC[sub60]BM ([6,6]-phenyl-C61-butyric acid methyl ester) to investigate competition between intermolecular energy transfer and interfacial charge transfer. Specifically, the difunctional SPS data illustrated enhanced and reduced energy transfer mechanisms that are dependent on the material composition of MEH-PPV and PC[sub60]BM. These data are indicative of changes in inter- and intrachain interactions of BPPV and MEH-PPV and their respective nanoscale morphologies. Together, these fundamental studies provide a thorough understanding of monofunctional and difunctional doped nanoparticle photophysics, necessary for understanding the morphological, optoelectronic and photophysical processes that can limit the efficiency of OPVs and provide insight for strategies aimed at improving device efficiencies.ID: 030646223; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 134-152).
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry
43
Ehrenhofer, Adrian, and Thomas Wallmersperger. "Adjustable fluid and particle permeation through hydrogel composite membranes." Sage, 2017. https://tud.qucosa.de/id/qucosa%3A74231.
Full textAbstract:
Membranes act as smart structures in respect to their permeation abilities. Control of particle and fluid permeation through a synthetic membrane can be achieved by using different effects like size-exclusion or electromagnetic interactions that occur between the particles and membrane pores. The simulation of controlled permeability provides an insight into the smart behavior of membranes for chemical signal processing, sensing interfaces or lab-on-a-chip devices. In the current work, we model the underlying physical processes on a microfluidic level using the engineer’s approach of laminar flow through pipes. Different pore geometries inside a composite membrane system consisting of a polyethylene terephthalate support membrane and a poly(N-isopropylacrylamide) hydrogel-layer are investigated. Simulations for different states of thermally induced pore opening are performed for free and blocked states. From the results we derive paradigms for the design of a membrane system for microfluidic cell-size profiling considering stimulus-range, pore shape and measurement setup.
44
Chandrasekaran, Swetha [Verfasser], and Karl [Akademischer Betreuer] Schulte. "Development of nano-particle modified polymer matrices for improved fibre reinforced composites / Swetha Chandrasekaran. Betreuer: Karl Schulte." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2014. http://d-nb.info/1059804107/34.
Full text
45
Chapel, Anthony. "Etude du comportement photochimique de revêtements composites polymère/particules luminescentes pour applications à l'éclairage éco-énergétique à base de LEDS. Impact du vieillissement sur les performances optiques." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22672/document.
Full textAbstract:
Les lampes à LEDs s’imposent comme la solution d’avenir pour l’éclairage vert de demain. Malgré des durées de vie annoncées par les constructeurs supérieures à 50 000h, une dérive prématurée de la qualité colorimétrique a été constatée. Ce travail de thèse porte sur l’influence de la photodégradation sur les propriétés optiques de l’un des composants d’un module LED : le composite luminescent qui est associé à la puce semi-conductrice. Des composites luminescents ont été élaborés à partir d’une matrice polymère (EVA ou PMMA) et d’un luminophore inorganique : Y3BO6 : 15% Eu3+. L’évolution des propriétés physico-chimiques et optiques de ces composites a été étudiée sous irradiation dans des conditions accélérées (λ>300 nm) et dans les conditions d’usage (LED UV, λ=365 nm). Le luminophore n’a pas montré d’effet prodégradant sur la photooxydation du polymère. Une perte des propriétés optiques du composite sous l’effet de la photodégradation du polymère a été mise en évidence dans le cas de la matrice EVA. L’évolution des paramètres photométriques de la lumière émise par les composites luminescents au cours du photovieillissement a pu être reliée à l’accumulation des photoproduits dans les films. En revanche, pour les composites PMMA/luminophore, la structure chimique et les propriétés optiques de ces composites ne sont pas modifiés pour des durées de photovieillissement accélérés de 4000hPhosphor-converted LEDs are emerging as an eco-friendly solution for the next generation lighting. Despite lifetimes claimed over 50 000h, a loss of the optical properties was noticed. This work focuses on the influence of photodegradation of the materials on the optical properties of the polymer/phosphor composite that is used to encapsulate the semiconductor chip. Luminescent composites were made from a polymer matrix (EVA or PMMA) and an inorganic phosphor: Y3BO6 :15% Eu3+. The evolution of physical, chemical and optical properties of these composites was investigated under irradiation in accelerated conditions (λ>300 nm) and in the use conditions of UV LED (λ=365 nm). The phosphor showed no pro-degrading effect on the photooxidation of the polymer. A loss of the optical properties of the composite was observed and ascribed to the photodegradation of the polymer in the case of the EVA matrix. The evolution of photometric parameters of the emitted light by the luminescent composite during photoaging can be attributed to the accumulation of photoproducts in films. However, for PMMA/phosphor composites, the chemical structure and optical properties of such composites are kept for accelerated photoaging time up to 4000h
46
Marquina, Edgar Alberto. "Use of Dynamic Mechanical Testing, WAXD and SEM Image Analysis to Study the Properties of Polypropylene/Calcium Carbonate Nanocomposites." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1269363578.
Full text
47
Schneider, Michael. "Renforcement de polymeres avec des particules composites de latex a base de caoutchouc naturel." Université Louis Pasteur (Strasbourg) (1971-2008), 1995. http://www.theses.fr/1995STR13216.
Full textAbstract:
L'evolution de nos travaux s'est deroulee selon une chronologie allant de la synthese en emulsion de particules composites a base de caoutchouc naturel et d'acrylate de butyle jusqu'a la mise au point de melanges binaires (polymere thermoplastique + particules) et ternaires (un polymere thermoplastique majoritaire + un second polymere thermoplastique minoritaire + particules). Cette etude avait pour objectif principal de definir les parametres qui gouvernent l'amelioration de la resistance aux chocs d'un melange modele dont on maitrise parfaitement la composition, la nature et l'interface de la phase dispersee. Les techniques de microscopie electronique a balayage et a transmission ont permis de correler la morphologie des particules renforcantes avec le mode de deformation des differentes matrices thermoplastiques utilisees
48
Laisney, Jérôme. "Influence de l’environnement sur la commutation et la bistabilité thermique de micro- et de nanoparticules à transition de spin." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112002.
Full textAbstract:
Les composés à transition de spin forment une classe spécifique de matériaux pour lesquels la commutation de l’état de spin du centre métallique peut être pilotée par divers stimuli (T, P, irradiation lumineuse, …) et s’accompagne de changements remarquables des propriétés physiques (magnétiques, optiques, structurales ou encore vibrationnelles). Ils se distinguent des autres matériaux commutables par l’observation, pour un certain nombre d’entre eux, de processus coopératifs à l’état solide, donnant lieu à l’ouverture d’une hystérèse thermique (bistabilité) particulièrement intéressante pour le stockage de l’information. Un des challenges technologiques actuels est de réduire la taille des matériaux susceptibles d’application et de les mettre en forme au sein de dispositifs sans altérer pour autant leurs propriétés. Les objectifs de la thèse ont été d’élaborer des micro- et nanoparticules à conversion de spin à partir de composés moléculaires présentant une transition de spin du premier ordre à l’état massif, puis d’étudier et analyser l’influence de la taille et de la matrice dispersante sur les processus de transition de spin. Après un premier chapitre introductif portant sur les matériaux à transition de spin, les méthodes de nanochimie et de mise en forme, le deuxième chapitre décrit l’élaboration de particules des composés FeII(phen)2(NCX)2 (X = S, Se) et [FeIII(3-OMeSalRen)2]PF6 (R = Me, Et). Comme la technique de précipitation rapide convient pour des composés ioniques, son application à FeII(phen)2(NCX)2 composé neutre, a nécessité la mise au point d’une synthèse indirecte de particules, basée sur l’extraction de ligand de précurseurs solubles, et le contrôle via des paramètres expérimentaux, des étapes de nucléation-croissance. De nouvelles particules de composés ioniques de Fe(III) [FeIII(3-OMeSalRen)2]PF6 (R = Me, Et) et des films minces contenant ces particules dispersées dans un polymère (PVP) ont été préparées. Les études magnétique et optique de ces films montrent que la matrice et la mise en forme modifient toujours les caractéristiques de la transition de spin des particules.La deuxième partie des travaux a été consacrée à l’étude des effets d’environnement. L’interaction entre des microparticules de Fe(phen)2(NCS)2 et des matrices vitreuses (Tg > T1/2; T1/2, étant la température de transition) peut conduire à l’ouverture d’un large cycle d’hystérésis, déplacé vers les plus basses températures. Cette zone de bistabilité a été examinée à l’aide de la méthode FORC (First-Order Reversal Curves). L’analyse a permis d’établir l’existence de composantes réversibles attribuées aux interactions élastiques à l’interface matrice/particule et au changement de volume de la particule à transition de spin.L’étude des effets de matrice et de taille a été poursuivie avec des micro- et nanocristaux de [FeIII(3-OMeSalEen2]PF6 dispersés dans des polymères ou des liquides moléculaires formant des verres à basse température. L’encapsulation dans des verres rigides de particules haut-spin (T1/2 < Tg) ou bas-spin (T1/2 > Tg) donnent lieu à des conversions de spin déplacées respectivement vers les plus basses ou plus hautes températures, éventuellement des processus coopératifs avec hystérésis. Le renforcement de la coopérativité et la bistabilité observées dans le second cas ont été interprétés comme résultant des contraintes mécaniques vis-à-vis du changement de volume BS-HS de la particule. Enfin, le changement d’état de la matrice induit par des étapes de trempe (ou recuit) en-dessous (au-dessus) de la température de transition vitreuse, a été exploité pour moduler ces effets. Dans la perspective d’une application, de nouvelles études de composites ont été engagées avec des complexes présentant une transition de spin proche de la température ambiante. Le choix de la matrice dispersante selon certains critères (nature chimique, température de transition vitreuse) a permis de retrouver certains effetsSpin-transition compounds are a class of materials for which the spin-state switching of the metal center can be controlled by various stimuli (T, P, light irradiation,...) and produces dramatic changes of physical properties (magnetic, optical, structural or vibrational). With respect to the set of switchable materials, a number of spin-transition compounds exhibit at solid-state cooperative processes and thermal hysteresis loops (bistability), particularly suitable for information storage. One of the current technological challenges is to integrate in devices such potentially interesting materials without altering their properties. The goal of the research, recently developed by several teams, is to determine the smaller size of object in which an information can be stored, and thus to understand the effect of downsizing on cooperativity and bistability. Therefore, the objectives of the Ph-D thesis were (i) to synthesize spin-crossover nano- and microparticles from molecular materials that in the form of bulk undergo a first-order phase transition; (ii), to investigate the importance of particles size and matrix effects on the spin-transition process.After a first chapter in which the spin crossover materials are introduced, the second chapter describes the synthesis of particles of FeII(phen)2(NCX)2 (X = S, Se) and [FeIII(3-OMeSalRen)2]PF6 (R = Me, E) compounds. As the fast precipitation technique essentially suits for ionic compounds, its application to neutral ones like FeII(phen)2(NCX)2, has been made possible by an indirect syntheses based on the ligand extraction from soluble precursors and the control of nucleation and growth processes of neutral products via experimental parameters. New particles of [FeIII(3-OMeSalEen)2]PF6 and thin films containing them after their dispersion in a polymeric matrix (PVP) have been prepared. The study of these films with UV-vis and magnetic measurements has raised the issue of the impact of the polymeric matrix and processing on the spin transition properties of these particles.The second part of the manuscript focuses on the interaction between the spin-crossover particles and the dispersing medium. This interaction between microparticles of Fe(phen)2(NCS)2 and glassy matrices (Tg > T1/2, T1/2, being the transition temperature) may result in the observation of large hysteresis loops shifted towards lower temperatures. This bistability has been examined with the FORC (First-Order Reversal Curves) method, magnetic measurements and a theoretical model. This analysis has shown the existence of reversible components associated to the particles/matrix interactions and the change of volume of spin-crossover particles.In a third part, the study of matrix and size effect has been pursued with micro- and nanocrystals of [FeIII(3-OMeSalEen2]PF6 encapsulated in polymeric or molecular liquids which form glasses at sufficiently low temperature. The encapsulation in rigid glasses of high spin (T1/2 < Tg) or low spin (T1/2 > Tg) particles give rise to transitions shifted towards lower or higher temperature respectively, possibly with cooperativity and hysteresis. The reinforcement of cooperativity and the bistability observed in the second case have been accounted for by the effect of the mechanical stress exerted by the glassy matrix on the particle volume. In addition, it has been shown that a thermal treatment of matrices (quenching or annealing steps below or above the glass transition) results in the modulation of the matrix effects. Finally, in the last chapter, a few composites including compounds undergoing a spin transition close to room temperature have been shortly investigated in presence of dispersing matrices. The choice of the matrices characteristics (chemical nature, glass transition temperature) has allowed some of these effects to be observed
49
De, Rancourt Yoann. "Dispersion de charges d'oxydes de terres rares, Er2O3 et Pr6O11, dans une matrice polymère." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20202.
Full textAbstract:
Ce travail de thèse porte sur l'incorporation de charges minérales d'oxyde d'erbium, Er2O3, et d'oxyde de praséodyme, Pr6O11, dans une matrice polymère de type élastomère, ceci dans le cadre d'un projet industriel de remplacement du plomb dans des équipements de radioprotection. L'objet de cette thèse était d'améliorer la dispersion des charges au sein de la matrice par le biais de procédés de traitements chimiques de ces particules. Divers types de fonctionnalisations de surface ont été employés afin de compatibiliser celles-ci avec une matrice organique, notamment par greffage de composés de type acides phosphoniques. Plusieurs acides phosphoniques ont ainsi pu être utilisés avec succès pour la fonctionnalisation des deux types de charges. La caractérisation de ces différentes fonctionnalisations représente une part importante de ce projet. Des techniques d'analyse innovantes, aussi bien directes qu'indirectes ont été employées dans ce but, à savoir de la Py-GC/MS pour la détection des composés ancrés à la surface des charges, de la fluorescence X et de la spectroscopie infrarouge dans un objectif de quantification, mais aussi des études cinétiques de sédimentation des charges dans un milieu liquide organique. Finalement, des composites ont pu être obtenus par mélange des charges, traitées et non traitées, avec une matrice polyuréthane. Des essais de traction ont permis de montrer clairement une amélioration des propriétés mécaniques de certains des composites, grâce à la fonctionnalisation des charges par les acides phosphoniquesThis thesis focuses on the incorporation of mineral fillers of erbium oxide, Er2O3, and praseodymium oxide, Pr6O11, in an elastomeric polymer matrix, in the context of an industrial project to replace the lead in radiation protection equipment. The actual purpose of this thesis was to improve the dispersion of the fillers in the matrix through chemical treatment processes of these particles. Various types of surface functionalization were used to compatibilize them with an organic matrix, in particular by grafting compounds such as phosphonic acids. Hence, several phosphonic acids have been successfully used for the functionalization of both types of fillers. The characterization of these functionalizations is an important part of this project. Innovative analysis techniques, both direct and indirect have been used for this purpose, namely Py-GC/MS to detect the chemical compounds anchored to the surface of the fillers, X-ray fluorescence and FTIR spectroscopy with a quantification target, but also a study of sedimentation kinetics of the fillers in an organic medium. Finally, composites were obtained by mixing the fillers, untreated and treated, with a polyurethane matrix. Tensile tests have clearly shown an improvement of mechanical properties for some of the composites, due to the functionalization of the fillers by phosphonic acids
50
Hölken, Iris [Verfasser]. "Mechanically stable and environmentally friendly polymer/particle composites for the application as low-fouling coating in the marine sector / Iris Hölken." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1115183621/34.
Full text