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Dissertations / Theses on the topic 'Blend Polymer'

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Published: 6 September 2023

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1

Williams, Peter W. "Polymer blend miscibility." Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/14459.

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A number of quasi-binary homopolymer blends have been investigated with regard to their miscibility. The blends consisted of poly(epichlorohydrin) (PEPC) mixed with a range of poly(methacrylate) polymers:- poly(methyl methacrylate); poly(ethoxyethyl methacrylate); poly(tetrahydrofurfuryl methacrylate) and poly(glycidyl methacrylate) (PGMA). It was found that the state of mixing of the systems varied with the structure of the ester side chain, embracing a number of miscibility states. It has been postulated that the observed miscibility in the system PGMA/PEPC is due to the presence of a small specific interaction between the species. A second category of blend investigated comprised of a homopolymer (PEPC) and a random copolymer. In two cases the copolymers (styreneco- methacrylonitrile; methyl methacrylate-co-methacrylonitrile) were chosen such that the cohesive energy density of PEPC lay between those of the comonomers. This led to the observation of a number of miscibility states for the systems, depending upon the copolymer composition. Analysis of these systems and similar examples in the literature was conducted using the mean-field approach. A reasonable accord between theory and experiment was found when the role of both specific interactions and free-volume terms was negligible. A third type of copolymer (glycidyl methacrylate-co-methyl methacrylate) was found to be only partially miscible with PEPC. This was due to the small GMA/PEPC interaction and the tendency of the copolymer to diverge from the copolymerisation equation at high GMA concentrations. The experimental probe for miscibility has been the glass transition temperature. This was determined using Differential Thermal Analysis, Dynamic Mechanical Thermal Analysis and to a lesser extent, Dielectric Relaxation. The phenomenon of partial miscibility, in which phase composition varies with overall blend composition, has been discussed. It has been postulated that this widely observed behaviour is due to a non-equilibrium phase separation process. The inadequacy of existing relationshi in describing the variation of the glass transition temperature of a miscible blend with composition has been highlighted. Furthermore, the importance of the transition width as an indicator of miscibility has been stressed.
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2

Liu, Yee-Chen. "Polymer blend light-emitting diodes." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610709.

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3

Sharudin, Rahida Wati Binti. "Carbon Dioxide Physical Foaming of Polymer Blends:-Blend Morphology and Cellular Structure-." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/161019.

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4

Tuladhar, Sachetan Man. "Charge transport in conjugated polymers and polymer/fullerene Blends : influence of chemical structure, morphology and blend composition." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445260.

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5

Wang, Shiping. "THICKNESS AND CRYSTALLINITY DEPENDENT SWELLING OF POLY (ETHYLENE OXIDE) /POLY (METHYL METHACRYLATE) BLEND FILMS." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556831245474707.

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6

Rajaram, Sridhar. "Quantitative image analysis and polymer blend coalescence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ45460.pdf.

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7

Manandhar, Sandeep. "Bioresorbable Polymer Blend Scaffold for Tissue Engineering." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc68008/.

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Tissue engineering merges the disciplines of study like cell biology, materials science, engineering and surgery to enable growth of new living tissues on scaffolding constructed from implanted polymeric materials. One of the most important aspects of tissue engineering related to material science is design of the polymer scaffolds. The polymer scaffolds needs to have some specific mechanical strength over certain period of time. In this work bioresorbable aliphatic polymers (PCL and PLLA) were blended using extrusion and solution methods. These blends were then extruded and electrospun into fibers. The fibers were then subjected to FDA standard in vitro immersion degradation tests where its mechanical strength, water absorption, weight loss were observed during the eight weeks. The results indicate that the mechanical strength and rate of degradation can be tailored by changing the ratio of PCL and PLLA in the blend. Processing influences these parameters, with the loss of mechanical strength and rate of degradation being higher in electrospun fibers compared to those extruded. A second effort in this thesis addressed the potential separation of the scaffold from the tissue (loss of apposition) due to the differences in their low strain responses. This hypothesis that using knit with low tension will have better compliance was tested and confirmed.
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8

Adhikari, Narayan Prasad. "Interfacial properties and phase behavior of unsymmetric polymer blends." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964276852.

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9

Pipich, Vitaliy. "Ordering transition and critical phenomena in a three component polymer mixture of A/B homopolymers and a A-B diblockcopolymer." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97119436X.

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10

Roths, Tobias. "Rheologische Charakterisierung polymerer Materialien statistische Datenanalyse, Modellbildung und Simulation /." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961227508.

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11

Steinmann, Sandra. "Neue morphologische und rheologische Kriterien für die Phaseninversion von ungefüllten und selektiv gefüllten Polymerblends." [S.l. : s.n.], 2002. http://www.freidok.uni-freiburg.de/volltexte/334.

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12

Düchs, Dominik. "Field theories for copolymer blends self consistent approaches and Monte Carlo simulations /." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967589339.

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13

Zhang, Yue Zhang. "Phase Separation of Polymer-grafted Nanoparticle blend Thin Films." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494885057468539.

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14

Wang, Yanbin. "Exciton Harvesting in Ternary Blend Polymer Solar Cells." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/192193.

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15

Bedia, Elinor L. "Structural Development and Properties of Polymer Blend Materials." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149853.

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16

Mori, Daisuke. "Development of Polymer Blend Solar Cells Composed of Conjugated Donor and Acceptor Polymers." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199331.

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17

Henry, Milliman W. "REINFORCEMENT OF MELT-BLEND COMPOSITES; POLYMER-FILLER INTERACTIONS, PHASE BEHAVIOR, AND STRUCTURE-PROPERTY RELATIONSHIPS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1323439686.

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18

Ziegler, Jonas. "Beeinflussung der Polymer-Füllstoff-Wechselwirkung durch Oberflächenmodifizierung von Füllstoffen." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97408929X.

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19

Strunk-Westermann, Andreas. ""In-situ"-Polymerisation von Methylmethacrylat in Gegenwart von Poly(n-butylacrylat) mit Poly(methylmethacrylat-block-n-butylacrylat) als Verträglichkeitsvermittler." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=963172077.

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20

Plawky, Udo. "Der Einfluss thermoplastischer Elastomere auf die Struktur und das Kristallisationsverhalten von Polyolefin-Blends." [S.l. : s.n.], 1997. http://deposit.ddb.de/cgi-bin/dokserv?idn=958615403.

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21

Yu, Erkang. "Herstellung und Charakterisierung von Blends aus technischen und hochtemperaturbeständigen Thermoplasten /." Berlin : TU, Univ.-Bibliothek, Abt. Publ, 2004. http://www.ub.tu-berlin.de/index.php?id=1546#c5049.

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22

Ghodgaonkar, Parag G. "Morphology development and compatibilization in immiscible polymer blend systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21166.pdf.

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23

Geoghegan, Mark. "Surface induced phase transitions in thin polymer blend films." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319888.

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24

Ogawa, Hiroki. "Phase Separation and Dewetting in Polymer Blend Thin Films." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/65600.

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Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(工学)<br>甲第14104号<br>工博第2968号<br>新制||工||1440(附属図書館)<br>26392<br>UT51-2008-L159<br>京都大学大学院工学研究科高分子化学専攻<br>(主査)教授 金谷 利治, 教授 伊藤 紳三郎, 教授 瀧川 敏算<br>学位規則第4条第1項該当
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25

Coveney, Sam. "Fundamentals of phase separation in polymer blend thin films." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/8146/.

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In this Ph.D. thesis, I investigate fundamental aspects of phase separation in polymer-blend thin films by unifying 1D phase equilibria with film evolution phenomena. I begin by extending a Hamiltonian phase portrait method, useful for visualising and calculating phase equilibria of polymer-blend films, allowing the method to be applied to systems with no convenient symmetries. Consideration of equilibria suggests a thermodynamic mechanism of film roughening, whereby laterally coexisting phases could have different depths in order to minimise free energy. I then make use of the phase portraits to demonstrate that simulations of lateral phase separation via a transient wetting layer, which conform very well with experiments, can be satisfactorily explained by 1D phase equilibria and a surface bifurcation mechanism involving effective boundary conditions caused by the film surfaces. Lastly, to tie together the aforementioned work, I introduce a novel 3D model of coupled phase separation and dewetting, for which I solved the problem of including a general non-uniform composition profile in the depth direction between the film surfaces. Pattern formation, in which surface roughening shadows the phase separation, seems to be determined by an interplay between dewetting kinetics and underlying phase equilibria.
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26

Mokarian-Tabari, Parvaneh. "Controlling the morphology of spin coated polymer blend films." Thesis, University of Sheffield, 2010. http://etheses.whiterose.ac.uk/15113/.

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Thin films of polymer mixtures made by spin-coating can phase separate in two ways - by forming lateral domains, or by separating into two distinct layers. The latter situation - self-stratification or vertical phase separation - could be advantageous in a number of practical applications, such as polymer photovoltaics. In our experiments, we have used time-resolved small-angle light scattering and light reflectivity during spin coating to study the structure development in PS/PMMA and PFB/F8BT blends, solution cast in toluene. A sample cell was designed, made and mounted on the apparatus to manipulate the evaporation rate. Having solved the Meyerhofer equation for thinning rate and by fitting the model to the experimental data, we are able to extract the evaporation rate of toluene during spin coating. We demonstrate that, by controlling the evaporation rate during the spin-coating process, we can obtain either selfstratification or lateral phase separation in the same system. We relate this to a previously hypothesised mechanism for phase separation during spin coating in thin films, according to which a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within the drying film. Our results show that a high evaporation rate leads to a laterally phase separated structure, while reducing the evaporation rate suppresses the interfacial instability and leads to a self-stratified final film. Using the set up we developed to control the morphology through evaporation rate, we made preliminary photovoltaic devices. It is possible to control the efficiency of the polymer photovoltaics by means of process parameters such as evaporation rate.
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27

Gallagher, G. A. "Mechanical properties and morphology of oriented polymer blends." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233174.

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28

Medeiros, Felipe Albuquerque. "Caracterização de blenda poli-cloreto de vinila e poli-metacrilato de metila, processamento, propriedades e potencial de aplicação." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-19032015-170252/.

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As blendas poliméricas são importante alternativa ao mercado para se conseguir de forma economicamente vantajosa ou sob o ponto de vista de processabilidade produtos com propriedades otimizadas para aplicações específicas. Blendas com razões de composição variadas entre diferentes polímeros atendem aplicações muitas vezes com requisitos intermediários entre materiais. Este trabalho revisa sucintamente a literatura sobre blendas poliméricas, a produção em laboratório de uma blenda mecânica de poli(cloreto de vinila) PVC e poli(metacrilato de metila) - PMMA, avalia as propriedades de blendas com frações variadas de PVC/PMMA e discute o potencial de aplicação no mercado. A blenda miscível caracterizada tem custo, resistência à chama e propriedades mecânicas e térmicas intermediárias aos dois polímeros puros.<br>Polymer blends are an important alternative in the market for achieving, in an economically and advantageous way or just considering processability products with optimized properties for specific applications. Blends with variable composition ratios, between two different polymers, fit to applications with intermediate requirements between two different materials. This paper reviews slightly the literature about polymer blends, the lab scale production of a mechanical blend of poli(vinylene vhloride) - PVC and poly(methyl metacrylate) - PMMA with different PVC/PMMA ratios and the application potential. The miscible blend shows intermediate cost, flame resistance, mechanical and thermal properties then those shown by its neat polymers.
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29

Vorobyova, Olga. "Fluorescence studies of polymer association in water and droplet coalescence in polymer blend melts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0018/NQ53685.pdf.

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30

Guo, Yuelei. "INVESTIGATION OF SILICONE RUBBER BLENDS AND THEIR SHAPE MEMORY PROPERTIES." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525982588046477.

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31

McGarey, B. "A study of sequential interpenetrating polymer networks based on polymethylsiloxane." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382407.

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32

Zhang, Wei. "Controllable growth of porous structures from co-continuous polymer blend." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39608.

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Due to their large internal surface area, microporous materials have been widely used in applications where high surface activity is desired. Example applications are extracellular scaffolds for tissue engineering, porous substrates for catalytic reaction, and permeable media for membrane filtration, etc. To realize these potential applications, various techniques such as TIPS (thermal induced phase separation), particle leaching, and SFF (solid freeform fabrication) were proposed and investigated. Despite of being able to generate microporous for specific applications, these available fabrication techniques have limitations on controlling the inner porous structure and the outer geometry in a cost-effective manner. To address these technical challenges, a systematic study focusing on the generation of microporous structures using co-continuous polymer blend was conducted. Under this topic, five subtopics were explored: 1) generation of gradient porous structures; 2) geometrical confining effect in compression molding of co-continuous polymer blend; 3) microporous composite with high nanoparticle loading; 4) micropatterning of porous structure; 5) simulation strategy for kinetics of co-continuous polymer blend phase coarsening process.
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33

Sohal, Nisha. "Solid state nuclear magnetic resonance studies of a polymer blend." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501767.

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34

Karami, Askar. "Polymer blend de-mixing and morphology development during tube flow." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/NQ41184.pdf.

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35

Holdsworth, Angela. "An investigation of the gas permeability of polymer blend membranes." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302956.

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36

Hodgson, Andrew William. "Solid-state nuclear magnetic resonance studies of a polymer blend." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401862.

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37

Kalloudis, Michail. "Thin polymer films of block copolymers and blend/nanoparticle composites." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7894.

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In this thesis, atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical microscopy techniques were used to investigate systematically the self-assembled nanostructure behaviour of two different types of spin-cast polymer thin films: poly(isoprene-b-ethylene oxide), PI-b-PEO diblock copolymers and [poly(9,9-dioctylfluorene-co-benzothiadiazole)]:poly[9,9- dioctyfluorene-co-N-(4-butylphenyl)-diphenylamine], F8BT:TFB conjugated polymer blends. In the particular case of the polymer blend thin films, the morphology of their composites with cadmium selenide (CdSe) quantum dot (QD) nanoparticles was also investigated. For the diblock copolymer thin films, the behaviour of the nanostructures formed and the wetting behaviour on mica, varying the volume fraction of the PEO block (fPEO) and the average film thickness was explored. For the polymer blend films, the effect of the F8BT/TFB blend ratio (per weight), spin-coating parameters and solution concentration on the phase-separated nanodomains was investigated. The influence of the quantum dots on the phase separation when these were embedded in the F8BT:TFB thin films was also examined. It was found that in the case of PI-b-PEO copolymer thin films, robust nanostructures, which remained unchanged after heating/annealing and/or ageing, were obtained immediately after spin coating on hydrophilic mica substrates from aqueous solutions. The competition and coupling of the PEO crystallisation and the phase separation between the PEO and PI blocks determined the ultimate morphology of the thin films. Due to the great biocompatible properties of the PEO block (protein resistance), robust PEO-based nanostructures find important applications in the development of micro/nano patterns for biological and biomedical applications. It was also found that sub-micrometre length-scale phase-separated domains were formed in F8BT:TFB spin cast thin films. The nanophase-separated domains of F8BT-rich and TFB-rich areas were close to one order of magnitude smaller (in the lateral direction) than those reported in the literature. When the quantum dot nanoparticles were added to the blend thin films, it was found that the QDs prefer to lie in the F8BT areas alone. Furthermore, adding quantum dots to the system, purer F8BT and TFB nano-phase separated domains were obtained. Conjugated polymer blend thin films are excellent candidates for alternatives to the inorganic semiconductor materials for use in applications such as light emitting diodes and photovoltaic cells, mainly due to the ease of processing, low-cost fabrication and mechanical flexibility. The rather limited optoelectronic efficiency of the organic thin films can be significantly improved by adding inorganic semiconducting nanoparticles.
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38

Ford, T. A. "Long-lived excitations in conjugated polymer blend films and devices." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599107.

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This thesis discusses the formation and decay of long-lived excited states within thin films and light-emitting diodes based on blends of polyfluorene-derived conjugated polymers. A polymer blend comprises two different conjugated polymers mixed together in a complex morphology. The formation of triplet excitons is studied in the blend system comprising poly(9,90dioctylfluorene-<i>co</i>-benzothiadiazole) (F8BT) and poly(9,9-dioctylfluorene-<i>co</i>-bis-<i>N,N-</i>(4-butylphenyl)-bis-<i>N,N-</i>phenyl-1,4-phenylenediamene) (PFB). The formation efficiency of triplet excitons is found to be several times higher in the blend than in either of the pristine polymers. Triplet excitons are formed at the interfaces between the two different polymers and the formation rate may be reduced with an external electric field. Two distinct interfacial states are known to exist in the F8BT:PFB polymer blend, a short-lived polaron pair and a long-lived exciplex state. Efficient intersystem crossing is shown to occur in both states. The rate of intersystem crossing is calculated as (4.6 ± 1.6) x 10<sup>6</sup>s<sup>-1</sup><sub> </sub>in the exciplex state and at least (2.2 ± 0.6) x 10<sup>7</sup>s<sup>-1</sup> in the polaron pair. Once formed, triplet excitons decay with two characteristic lifetimes, corresponding to free and trapped triplets. In a polymer LED, polaron pair states are formed from the association of injected electrons and holes. The fast rate of intersystem crossing noted in the polaron pair suggests that the single formation fraction in a polymer LED may differ from the 25% suggested by simple spin statistics. Two experimental methods are used to calculate the singlet fraction in an F8BT:PFB LED. The singlet fraction, at low applied voltage, is found to be below 20% which corresponds to a fast relaxation from the triplet polaron pair states to the triplet exciton.
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Phillips, Matthew David. "Magnetic field effects in conjugated polymer blend films and devices." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609464.

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40

Chung, Geun-Chang Kornfield Julia A. Kornfield Julia A. "Segmental dynamics of individual species in a miscible polymer blend /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-09182007-103953.

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41

Zapata, Pedro José. "High throughput characterization of cell response to polymer blend phase separation." Thesis, Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-07082004-160241/.

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42

Walker, Teri Anne. "Modification of Polymer Blend Phase Behavior with High-Pressure Carbon Dioxide." NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-06152003-142608/.

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While much progress has been made since the time of Flory and Huggins in the understanding of polymer blend thermodynamics, and ongoing research continues to elucidate how polymer blend phase behavior is affected by the presence of small-molecule solvents or exposure to elevated pressures, very little work has been reported on the combined effects of a pressurized small-molecule solvent on polymer blend phase behavior. The focus of this research is to improve the current state of fundamental understanding regarding how and why the phase behavior of polymer blends changes as pressurized carbon dioxide (CO<sub>2</sub>) is added. The first part of this work provides a broad overview of previous efforts that explore various thermodynamic and kinetic processes involving the use of CO<sub>2</sub> in conjunction with multicomponent polymer systems. The following chapters discuss details of research performed primarily on three blend systems: polystyrene (PS)/polyisoprene (PI), poly(vinylidene fluoride) (PVDF)/ poly(methyl methacrylate) (PMMA), and polydimethylsiloxane (PDMS)/poly(ethylmethylsiloxane) (PEMS). The competing roles of hydrostatic pressure and CO<sub>2</sub> dissolution on the phase behavior of both the PS/PI and the PDMS/PEMS blends, which exhibit upper critical solution temperature (UCST) behavior, are systematically established. Additionally, a complete pseudo-binary temperature-composition phase diagram of the PDMS/PEMS blend is generated as a function of CO<sub>2</sub> pressure. To compare the predictive abilities of the Flory-Huggins and Sanchez-Lacombe equations of state, interaction parameters of the PDMS/PEMS blend are predicted as functions of temperature and CO<sub>2</sub> pressure. The phase behavior of, as well as intermolecular interactions in, PMMA/PVDF blends have been probed in the presence of CO<sub>2</sub> by small-angle neutron and x-ray scattering (SANS and SAXS, respectively). These PMMA/PVDF blends, which display both UCST and lower critical solution temperature (LCST) behavior, are also characterized before and after exposure to CO<sub>2</sub> by transmission electron microscopy and differential scanning calorimetry, which together confirm the propensity for CO<sub>2</sub>-induced PVDF crystallization.
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43

Bélanger, Christian. "Characterization of polymer blend morphology from patterns of reflected scattered light." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39740.

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The morphology and properties of polymer blends are closely related to processing conditions. The minor phase dimensions usually range from 0.1 to 10 $ mu$m. A skin/core morphology, with a minor phase undergoing variations in orientation and aspect ratio from the surface to the core of the material is observed in processes such as the injection molding of blends. The use of optical inspection is a potential tool to control the stability and the quality of the product on-line. In this thesis, polymer composites made from different glass fibers and glass microspheres embedded in a matrix of PS are used to simulate two-phase polymer blend morphology with a skin/core configuration. Two apparatuses have been used to characterize the morphology of the specimen by light scattering in reflection. The first had an incident light beam at 45 degrees from a normal to the surface of the sample. The second apparatus projected the laser beam incident perpendicularly on the surface of the sample and used polarized light. Distinctive reflected light scattering patterns were obtained in both cases and analyzed. In the first case, ratios of the axes of the ellipsoidal iso-intensity curves were plotted as a function of the position from the center of the light beam. The anisotropy of the iso-intensity lines is also plotted as a function of the position of the center of the beam for the second case. In both situations, information is obtained from the change of the anisotropy ratio as function of the distance from the center of the beam for depth-varying morphology samples. The skin, and the core content as well as the skin thickness effect can be isolated from the processed images. The second technique gave more information and patterns which were easier to process.<br>A Monte Carlo program was written to simulate the propagation of photons in the samples containing a spherical morphology. The simulation is a potential tool for the analysis or two-phase systems but requires further development to be a useful tool.
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44

Gonzalez-Rabade, A. "Correlation of heterojunction luminescence and photocurrent in polymer blend photovoltaic diodes." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599488.

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This thesis focuses on the electronic and photophysical phenomena that occur at the heterojunction between two distinct organic semiconductor materials. The hetero junction luminescence is correlated to the photovoltaic performance in a polymer blend diode. Polymer semiconductor blends allow efficient operation of photovoltaic diodes when there is a large interfacial area of hetero junction between electron donor and acceptor polymers. In this thesis, we use electromodulation spectroscopy to investigate the luminescent and photovoltaic behaviour of electron- and hole-transporting polyfluorenes blends at a broad range of blend ratios, temperatures and electric fields. In the systems investigated, an exciton at the hetero junction produces either free charges or an exciplex (or a similar interfacially-bound charge-transfer pair). We find that an externally-applied electric field increases the number of free charges and quenches the exciplex luminescence with a one-to-one correspondence: the increase of the photocurrent internal quantum efficiency is equal to the reduction in the exciplex emission. We conclude that, independent of temperature and morphology, the photovoltaic quantum yield is predominantly limited by the dissociation of the geminate electron-hole pair intermediate at the hetero junction. Once the charges are fully separated they are transported across the material and collected at the external circuit with nearly unit efficiency.
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45

Vlerken, Lilian Emilia van. "Modulation of multidrug resistance in cancer using polymer-blend nanoparticles : thesis /." Diss., View dissertation online, 2008. http://hdl.handle.net/2047/d10017355.

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46

Sadhu, Veera Bhadraiah. "Creation of crosslinkable interphases in polymer blends by means of novel coupling agents." Dresden : w.e.b, 2004. http://deposit.d-nb.de/cgi-bin/dokserv?idn=972369090.

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47

Albrecht, Mirko, and Michael Gehde. "Welding of incompatible thermoplastic polymers." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-204024.

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Due to the wide range of properties of plastics (e.g. low density), more and more conventional materials are substituted by polymer materials. Complex requirement profiles on technical parts increase the demand for joining processes that enable the reliable joining of otherwise incompatible thermoplastics. In this case, material bonded connections are approaching their limits. In the following study two incompatible thermoplastic polymers were welded by using polymer blends that are compatible to both components. Industrially relevant thermoplastics polyethylene (PE) and polyamide 12 (PA12) were chosen to demonstrate the potential of an innovative joining technology.
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48

Mattsson, Sandra. "Microscopy techniques for studying polymer-polymer blends." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-157990.

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Semiconductors are used in many electronic applications, for example diodes, solar cells and transistors. Typically, semiconductors are inorganic materials, such as silicon and gallium arsenide, but lately more research and development has been devoted to organic semiconductors, for example semiconducting polymers. One of the reasons is that polymers can be customized, to a greater extent than inorganic semiconductors, to create a material with desired properties. Often, two polymers are blended to obtain the desired function, but two polymers do not usually result in an even blend. Instead they tend to separate from each other to varying degrees. The morphology of the blend affects the material properties, for example how efficiently it can convert electricity to light. In this project, thin films consisting of polymer blends were examined using microscopy techniques for the purpose of increasing our understanding of the morphology of such blends. One goal was to investigate whether a technique called correlative light and electron microscopy can be useful for examining the morphology of these films. In correlative light and electron microscopy, a light microscope and an electron microscope are used in the same location in order to be able to correlate the information from the two microscopes. The second goal was to learn about the morphology of the thin films using various microscopy techniques. The polymers used were Super Yellow and poly(ethylene oxide) with large molecular weight. Super Yellow is a semiconducting and light-emitting polymer while poly(ethylene oxide) is an isolating and non-emitting polymer that can crystallize. In the blend films, large, seemingly crystalline structures appeared. The structures could be up to 1 mm in the lateral direction, while the films were only approximately 170 nm thick. These structures could grow after the films had dried and their shapes were similar to those of poly(ethylene oxide) crystals. Consequently, there is reason to believe that it is the poly(ethylene oxide) that makes up the seemingly crystalline structures, but the structures also emitted more light than the rest of the film, and Raman spectroscopy showed that there was Super Yellow in the same location as the crystals. Among the microscopy techniques used, phase contrast microscopy was particularly interesting. This method visualizes differences in optical path length and was useful for studying polymer blends when the polymers have different indices of refraction. Correlating light and electron microscopy showed that there was a pronounced topographical difference between the seemingly crystalline regions and the rest of the thin film. Light microscopy has a limited resolution due to diffraction, but as long as the resolution of the light microscope is sufficient for seeing phase separation, correlative light and electron microscopy turned out to be a good method for studying the morphology of thin films of polymer blends.<br>Halvledare är viktiga för många elektroniska ändamål eftersom de kan användas till exempelvis dioder, solceller och transistorer. Traditionellt används inorganiska halvledande material som kisel eller galliumarsenid, men på senare tid har allt mer forskning och utveckling inriktat sig mot organiska (kolbaserade) halvledare, såsom halvledande polymerer, bland annat eftersom det i högre utsträckning går att skräddarsy de organiska materialen så att de får önskvärda egenskaper. Ofta blandas två polymerer med varandra för att skapa ett material med nya egenskaper som är önskvärda, men två polymerer brukar inte blandas jämnt utan tenderar att separera från varandra i olika utsträckning. Hur blandningen ser ut (morfologin) påverkar materialets egenskaper, till exempel hur effektivt det omvandlar ström till ljus. Med syfte att öka förståelsen för hur morfologin ser ut hos en blandning av två polymerer, har detta projekt gått ut på att undersöka tunna filmer av polymer-blandningar med hjälp av mikroskopiska tekniker. Ett delmål var att ta reda på om en teknik som heter korrelativ ljus- och elektronmikroskopi är en bra metod för att undersöka morfologin hos dessa filmer. Vid korrelativ ljus- och elektronmikroskopi används både ett ljusmikroskop och ett elektronmikroskop på samma plats för att kunna korrelera informationen som de båda mikroskopen ger. Det andra delmålet var att undersöka vad de olika mikroskopi-teknikerna kan säga om morfologin hos de tunna filmerna. De polymerer som använts är Super Yellow och poly(etylenoxid) med hög molekylmassa. Super Yellow är en oordnad halvledande och ljusemitterande polymer medan poly(etylenoxid) är en isolerande och icke-emitterande polymer som kan kristallisera. I de blandade filmerna uppstod stora kristall-liknande strukturer som kunde vara upp emot 1 mm breda trots att filmerna bara var ungefär 170 nm tunna. Dessa strukturer kunde växa fram efter det att filmerna redan hade torkat och påminde i form om kristaller som kan bildas av poly(etylenoxid). Det finns alltså skäl att tro att det är poly(etylenoxid) som kristalliserats, men de kristall-liknande strukturerna visade sig emittera mer ljus än vad resten av filmen gjorde, och Raman-spektroskopi visade att det även fanns Super Yellow på samma plats som kristallerna. Bland de mikroskopitekniker som testades utmärker sig faskontrastmikroskopi, som visar skillnader i den optiska vägskillnaden (det vill säga faktisk vägskillnad multiplicerat med brytningsindex). Det visade sig vara en intressant teknik för att studera polymerblandningar när de båda polymererna har olika brytningsindex. Genom att korrelera ljus- och elektronmikroskopi visade det sig att det fanns en tydlig skillnad i struktur mellan de kristall-liknande områdena och resten av den tunna filmen. Ljusmikroskopi har begränsad upplösning på grund av ett fenomen som heter diffraktion, men så länge som ljusmikroskopets upplösning är tillräcklig för att se fasseparation visade det sig att korrelativ ljus- och elektronmikroskopi är en bra metod för att studera morfologin hos tunna filmer av polymerblandningar.
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49

Anselmo, Ana Sofia. "The morphology of polyfluorene : fullerene blend films for photovoltaic applications." Licentiate thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-7950.

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Polymer photovoltaic systems whose photoactive layer is a blend of a semiconducting polymer with a fullerene derivative in a bulk heterojunction configuration are amongst the most successful organic photovoltaic devices nowadays. The three-dimensional organization in these layers (the morphology) plays a crucial role in the performance of the devices. Detailed characterization of this organization at the nanoscale would provide valuable information for improving future material and architectural design and for device optimization. In this thesis, the results of morphology studies of blends of several polyfluorene copolymers (APFOs) blended with a fullerene derivative are presented. Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy was combined with dynamic Secondary Ion Mass Spectrometry (dSIMS) for surface and in-depth characterization of the blend films. NEXAFS was performed using two different electron detection methods, partial (PEY) and total (TEY) electron yield, which provide information from different depth regimes. Quantitative compositional information was obtained by fitting the spectra of the blend films with a linear combination of the spectra of films of the pure components. In blends of APFO3 with PCBM in two different blend ratios (1:1 and 1:4 of polymer:fullerene) NEXAFS data show the existence of compositional gradients in the vertical direction for both blend ratios, with clear polymer enrichment of the free surface. A series of APFOs with systematic changes in the side-chains was studied and it was shown that those small modifications can affect polymer:fullerene interaction and induce vertical phase separation. Polymer-enrichment of the free surface was clearly identified, in accordance with surface energy minimization mechanisms, and a compositional gradient was revealed already in the first few nanometers of the surface of the blend films. dSIMS showed that this vertical phase separation propagates throughout the film. It was possible to determine that as the polar character of the polymer increases, and thus the polymer:fullerene miscibility is improved, the tendency for vertical phase separation becomes stronger.<br><p>Paper II was not published at the time of the licentiate defence and had the title: NEXAFS spectroscopy study of the surface composition in APFO3:PCBM blend films</p>
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50

Kohlhoff, Dominik. "Experimental Preparation of Microcellular Polymer Blend Foams by Exploiting Structural non-Homogeneity." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/165027.

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