Dissertations / Theses on the topic 'Polymer blends'
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Muangpil, Sairoong. "Functionalised polymers and nanoparticle/polymer blends." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654111.
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The incorporation of nanoparticles into polydimethylsiloxane polymers either in the form of physical blending or chemical crosslinking has long been studied as it can improve the properties of composite materials. Interactions between the host polymer and the filler particle, filler concentration and conformation of each component are the key factors that influence these properties. Understanding the effect of these factors is of fundamental importance in all practical applications of composite materials. This thesis describes the study of a range of PDMS composites by using a variety of experimental techniques. The main techniques used were spin-spin (T2) relaxation and diffusion NMR spectroscopy, rheology and small-angle neutron scattering (SANS). The molecular mobility of a series of PDMS melts has been studied for both unentangled and entangled molecular weight regimes separated by the critical entanglement molecular weight (Mc) of the polymer. The experimental results revealed the effect of molecular weight and polydispersity of the polymers on their segmental mobility. The dramatic decrease of chain mobility observed at molecular weight above Mc was attributed to the effect of chain entanglements. The effect of nano-sized trimethylsilylated polysilicate resin (R2) on the chain mobility of PDMS in the form of physically blended was also examined. Two different concentrations (17 and 30 vol%) of R2 were incorporated into a wide range molecular weight of PDMS melts. Below Mc, the R2 particle was found to reinforce the PDMS at all particle loadings, whereas a plasticisation effect was observed for high molecular weight PDMS above Mc. This was attributed to a reduction of the degree of the entanglements when polymer chains adsorbed on particles. Chemically bonded composites of PDMS and polyhedral oligomeric silsesquioxane (POSS) were successfully synthesised via hydrosilylation. The length of the PDMS central block was found to affect both the size and the molecular mobility of the triblock polymers. The weight fraction of POSS and substituted groups on POSS were also seen to affect the molecular mobility. Finally, a series ofrandom crosslink polymer films ofPDMS and phenylsilsesquioxane (TPh) was studied by AFM, TEM, SAXS and SANS techniques to investigate the factors influencing the optical clarity of the samples. The degree of swelling and the segmental mobility of the sample films swollen in good and poor solvents were also studied.
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Singh, V. B. "Polyethersulphone polymer blends." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37855.
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Masson, Jean-François. "Cellulosesynthetic-polymer blends." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74661.
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Blends of cellulose (CELL) with polyvinyl pyrrolidone (PVP), poly(4-vinyl pyridine) (P$ sb4$VPy), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), poly($ epsilon$-caprolactone) (PCL), and nylon 6 (Ny6), and of chitosan with PVA were investigated in an attempt to gain some insight into the factors that affect the miscibility of cellulose with synthetic polymers. The miscibility and the scale of mixing of the various blends were studied by differential scanning calorimetry, dynamic mechanical analysis, infrared and NMR spectroscopy, and proton spin-lattice relaxation measurements. The CELL/PVP, CELL/P$ sb4$VPy, and chitosan/PVA blends were shown to be homogeneous at the molecular level, while the CELL/PAN blends were shown to mix on a larger scale. In contrast the CELL/PCL and CELL/Ny6 blends were essentially immiscible; from this it was concluded that the potential for strong inter-molecular interactions is not a sufficient condition for miscibility to occur in cellulose/synthetic-polymer blends.
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Manda, Dimitra. "Thermodynamics of polymer blends." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300415.
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Bhutto, Ali Asghar. "Miscibility of polymer blends." Thesis, Brunel University, 1999. http://bura.brunel.ac.uk/handle/2438/7392.
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In this work an attempt is made to correlate polymer miscibility with diffusion and with molecular interactions. A system with lower critical solubility temperature has been selected, namely polystyrene (PS) and polyvinyl methyl ether (PVME). Most of the published work has been done on polymers in solutions or on solvent cast specimens and therefore on ternary systems. The role of solvent has not yet been fully evaluated and it was of interest to compare the results on solvent cast samples with those prepared by mechanical blending and by diffusion. Molecular interaction is dependent on functional groups present and for this reason experiments have been performed on PVME blends with PS of different levels of sulfonation (SPS). Selective deuteration (d-PS) was used to identify and assign some absorption peaks in the infrared spectra. DSC measurements have shown that only one Tg is present for all blends prepared by solvent casting. It was necessary to use an extreme quenching rate down to liquid nitrogen in order to preserve the high temperature (above 150°C) phase separated structure, represented by two Tg of homopolymers. The mechanically blended system, on the other hand, did not show a single T g of the blend, unless annealed for one day at 110°C. This confirms the results obtained by diffusion studies using light microscopy and neutron reflectivity, that the diffusion rates are extremely slow and therefore do not control the phase formation and separation processes. These experiments also indicate that the microstructures of solvent cast samples and samples prepared by mechanical blending are different. The Tg of mechanical blended polymers indicate, that the composition of diffusion swollen PS does not correspond to the phase diagram measured in solutions, confirming thus the above result. The FTIR studies at different temperatures have shown that changes in spectra of polymer blends, as reported in the literature can be explained by temperature changes in pure homopolymers. This indicates that molecular interactions, which are responsible for miscibility, are not detectable by infrared absorptions and are therefore of unspecified strength and location. The FTIR of SPSIPVME blends show that sulfonate groups on PS affect polymer miscibility through changes in configuration of molecules, rather than through direct interaction with the PVME, as suggested in the literature. An attempt has been made to study diffusion of SPS and polycarbonate (PC) system by neutron reflectivity. Preliminary results indicate that surface relaxation effects make the data interpretation difficult.
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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.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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Julien, Grégoire. "Dynamics in polymer blends and polymer-solvent blends close to the glass transition." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10187/document.
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Dans ce travail, nous proposons un modèle qui décrit la dynamique dans les mélanges de polymères et polymère-solvant à l'approche de la transition vitreuse. Le modèle est résolu sur un réseau 2D sur des échelles de 10 nm à plusieurs microns. Ce modèle incorpore l'aspect hétérogène de la dynamique à l'échelle d'une hétérogénéité dynamique (3-5 nm). Dans le cas des mélanges de polymères, nous appliquons ce modèle afin d'étudier la séparation de phase lorsque le système est refroidi proche ou sous Tg, et le rajeunissement lorsque le système est réchauffé dans un état miscible et fondu. Pendant la séparation de phase, nous observons que des morphologies lentes se forment en coexistence avec des morphologies rapides. Pendant ce temps, la dynamique globale du système se ralentit et les domaines croissent comme le logarithme du temps. Lors de la réchauffe en revanche, nous observons que les domaines vitreux fondent plus vite que le temps nécessaire pour qu'ils se forment lors de la séparation de phase. Dans le cas des mélanges polymère-solvant, le système est en contact avec un réservoir de solvant et est en dessous de la température de transition vitreuse du polymère pur. L'activité du réservoir peut être changée afin de décrire le séchage ou le gonflement de films. Notre modèle permet de décrire la diffusion cas-II lorsqu'un polymère vitreux est plastifié par du solvant qui pénètre le système. Concernant le processus inverse de séchage, nous montrons que des films ayant des épaisseurs inférieures à 1 micron peuvent être séchés entièrement. Pour des films plus épais, en revanche, une croûte vitreuse se forme sur la surface libre du filmIn this work, we propose a model for describing the dynamics in polymer blends or polymer-solvent blends close to and below Tg. The model is solved on a 2D lattice corresponding to spatial scales from 10 nm up to a few micrometers and incorporate the heterogeneous nature of the dynamics at the scale of a dynamic heterogeneity (3-5 nm). In case of polymer blends, we apply this model to study phase separation close to and below Tg upon cooling, and rejuvenation in miscible range upon heating. In the course of phase separation, we observe slow structures forming in coexistence with faster ones. In the same time, the global dynamics of the system slows down and domains grow like the logarithm of the time. During rejuvenation, we observe that morphologies melt much faster the elapsed time required to build them during aging. In the case of polymer-solvent blends, the system is put in contact with a solvent reservoir and is at temperatures far below the pure polymer glass transition. We consider situations where the activity of the solvent reservoir is varied in order to describe either films drying or swelling. Our model allows for explaining case-II diffusion in the context of the plasticisation of a glassy polymer by penetrating solvent during swelling. Regarding the process of film drying, we show that films up to 1 micrometer thick can be completely dried. When drying a thicker film, we show that a glassy crust may appear on the free surface, as shown experimentally
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Guo, Molin. "PROCESSING-STRUCTURE-PROPERTY RELATIONSHIPS INCO-CONTINUOUS POLYMER BLENDS AND COMPOSITES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1593786851492932.
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Huynh, Anh Nhut Materials Science & Engineering Faculty of Science UNSW. "Rubber-polymer blends: a thesis in polymer engineering." Awarded by:University of New South Wales. Materials Science & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40833.
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This study examines composite materials prepared from ground recycled tires (tire crumb) and post-consumer recycled high density polyethylene (HDPE). An initial set of composites was prepared from as-received tire crumb and HDPE recyclate containing 040% tire crumb in 10% increments, using injection moulding. The elastic modulus and tensile strength were found to decrease linearly with increasing tire crumb content. Addition of tire crumb to recycled HDPE caused produced an immediate reduction in the strain to failure with a progressively more modest decrease as the tire crumb content was increased. The impact toughness decreased more linearly with increasing tire crumb fraction. Cross sections of the composites showed that the tire crumb particles were in intimate contact with the matrix but post mortem examination of the fracture surface of the impact test specimens indicated that the level of bonding had been poor. A second set of composites was a prepared from 10% tire crumb. The tire crumb was first given an oxidative treatment in hot aqueous copper chloride at concentrations from 0-5 wt% Cu Ch at 50 or 100??C for 6 or 12 hours. The composites were injection moulded with an addition of 0.5 wt% dicumyl peroxide (DCP). These composites showed good bonding between the tire crumb and the recycled HDPE even at concentrations of 0% of the Cu 2+ oxidation catalyst. The addition of DCP was found to substantially reduce the modulus of neat HDPE and this reduction was reflected in the modulus of the composites. It was found that the DCP concentration could be reduced to 0.02% without adversely affecting the composites.
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Milner, V. A. "Miscibility predictions in polymer blends." Thesis, Lancaster University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332385.
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Clark, Jane Northen. "Intermolecular interactions in polymer blends." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47811.
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Gamini, Seneviratne Weerasekara Mudiyanselage. "Phase separation of polymer blends." Thesis, University of Sussex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293398.
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Jackson, Stuart Thomas. "Surface analysis of polymer blends." Thesis, University of Sheffield, 1993. http://etheses.whiterose.ac.uk/14740/.
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Lee, Minhee. "Extrusion of polymers and polymer blends with supercritical carbon dioxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ51208.pdf.
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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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Jones, R. A. L. "Mutual diffusion in miscible polymer blends." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233254.
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Recent theories have suggested that mutual diffusion between miscible polymers may be strongly influenced by the unusual thermodynamics of mixing of high polymers; in addition the mobility properties of polymer blends are not, in general well understood. This dissertation describes experiments to investigate how these factors influence mutual diffusion in miscible polymer blends. After a general introduction and a review of some recent theories of mutual diffusion in polymer blends, experiments are described in one miscible blend system, Polyvinyl Chloride (PVC)/Polycaprolactone (PCL);x-ray microanalysis in a scanning electron microscope was used to measure the concentration dependence of the mutual diffusion coefficient. To explain this concentration dependence we need to invoke not only the thermodynamics of mixing but also the dependence on composition of the monometric friction coefficients in the system. This dependence was investigated using an ESR spin probe technique. The final section of the dissertation deals with an attempt to use the potentially powerful ion beam analysis techniques of Rutherford Backscattering (RBS) and Forward Recoil scattering (FReS) to measure mutual diffusion coefficients, as well as intradiffusion coefficients (whose concentration dependence should not be influenced by thermodynamic effects). Results obtained by these techniques are presented for three blend systems, including PVC/PCL; the results by RBS for the latter system are consistent with the results obtained by x-ray microanalysis.
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El-Begawy, Salah El-Din Moustafa. "Miscibility in polymer blends during copolymerization." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305127.
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Morley, Kevin P. "Criteria of failure for polymer blends." Thesis, Manchester Metropolitan University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303218.
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Webb, W. D. "Gas transport in miscible polymer blends." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37890.
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Słota-Newson, Joanne Elizabeth. "Diblock compatibilizers in optoelectronic polymer blends." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610183.
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Deb, Nabankur. "Morphological studies in polymer-fullerene blends." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54381.
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Polymer-fullerene blend systems have found relevance and application in a number of fields including organic photovoltaic devices. While synthesizing new materials with desirable electronic properties is essential to designing better photovoltaic devices, it is equally important to understand the complex phase morphology of these blends and its effect on device performance. Consequently, this knowledge could be used to further design new materials and device architecture for more efficient systems. In particular, this dissertation focuses primarily on the morphology in a series of amorphous as well as semi-crystalline polymer-fullerene blend systems both in bulk and thin films and its relation to device performance. Scattering based techniques have been used to determine in-plane and out-of-plane phase morphology. Morphological parameters derived from these studies have shown possible correlation between fullerene segregation and device performance values. The results of these studies have been used to synthesize a thermo-cross-linkable fullerene acceptor having slower diffusion through the polymer, allowing better control of the polymer-fullerene blend morphology. Consequent effects have been studied on device lifetime and thermal stability and have shown significant improvements
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Robertson, Christopher G. "Physical Aging of Miscible Polymer Blends." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/40427.
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Physical aging measurements were performed on various polymeric glasses with the overriding goal of developing a better molecular picture of the nonequilibrium glassy state. To this end, aging-induced changes in mechanical properties and in the thermodynamic state (volume and enthalpy) were assessed for two different miscible polymer blends as a function of both composition and aging temperature. This investigation considered the physical aging behavior of blends containing atactic polystyrene (a-PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) as well as mixtures of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN). Substantial attractive chemical interactions are characteristic of a-PS/PPO blends but are absent in PMMA/SAN blends. The distinct nature of interactions for these two blends resulted in differences in the compositional dependence of secondary relaxation intensity, segmental cooperativity which dictates glass formation kinetics, and density (prior to aging). The variation of volume relaxation rate with aging temperature and composition was interpreted based upon these characteristics for the two systems. In addition, a general relationship was uncovered which linked structural relaxation rates for amorphous polymers to their respective segmental relaxation characteristics (glass transition cooperativity or fragility), which in turn are well understood from a molecular standpoint. This work, therefore, established a basis for comprehending glassy state volume and enthalpy relaxation rates based upon molecular characteristics. Developing an understanding of the connection between the evolving thermodynamic state and mechanical property changes fared less well. The fact that the thermodynamic and mechanical properties can have very different relaxation time responses governing their changes in the nonequilibrium glassy state was clearly evident in an extensive study of the physical aging characteristics of an amorphous polyimide material. For some materials, interpretation of mechanical aging behavior was obscured by thermorheological complexity arising due to overlap of a secondary relaxation with the main chain softening dispersion.Ph. D.
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Parker, M. A. "The electron microscopy of polymer blends." Thesis, Brunel University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353861.
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Lim, Kate. "Supramolecular polymer blends for composite matrices." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/66400/.
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This research project reports a new approach to thermoplastic composite matrix design, in which a low-MW polymer additive acts as a plasticiser and flow-promoter at high temperatures, but as a non-covalent cross-linking agent at lower temperatures. Thus, poly(aryl ether ketone)s (PAEKs) are functionalised with π-electron rich terminal groups and blended with π-electron deficient polyimides. A non-covalent charge-transfer stacking interaction between the two polymers forms a self-assembled supramolecular network. Carbon fibre composites with matrices composed of these supramolecular polymer blends were produced, and the thermomechanical performance of these materials are reported. In designing functionalised PAEKs, novel benzoyl-pyrene and -perylene derived compounds were synthesised. The synthesis of these compounds and their subsequent use as functional end-groups in polycondensations are also discussed. During the course of polymer synthesis, the effect of varying polymerisation conditions involving different alkali metal carbonates was systematically investigated. It was found that monomer sequence distribution in PAEKs can be controlled by changing the alkali metal cation used in the nucleophilic synthesis. The mechanism of modifying monomer sequence distribution is presented herein. Investigating the interaction of polycyclic aromatic molecules pyrene and perylene with binary co-polyimides containing both strongly-binding and weakly-binding diimide sequences results in the emergence of fractal-like patterns in the 1H NMR spectra of the polyimide. The polyimide spectrum at high intercalator loadings shows self-similarity over a range of different length scales.
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Mamun, Chowdhury K. "Spatial modulation in crosslinked polymer blends /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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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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Kanhegaonkar, Shivkalyan A. "Studies on conducting polymers: synthesis and characterization of conducting polymer blends." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2873.
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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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Johnson, Jack Royce III. "POLYMER BLENDS, COMPOSITES AND AEROGEL MODIFICATION BY INNOVATIVE APPROACHES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1317409667.
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Ju, Lin. "Non-Covalent Interactions in Polymeric Materials: From Ionomers to Polymer Blends." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102651.
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Conventional studies of ionomers have focused on ionomers bearing monovalent carboxylate or sulfonate pendant ions. There are relatively fewer studies on ionomers containing multivalent pendant ions, such as divalent phosphonate. In this dissertation, poly(ethylene terephthalate) (PET) and polystyrene ionomers with divalent phosphonate pendant ions have been synthesized, and the influence of divalent phosphonate pendant ions on the structure-morphology-property relationship has been compared to the ionomers with monovalent sulfonate pendant ions. The phosphonate groups generated a stronger physically crosslinked network in phosphonated ionomers as compared to sulfonated analogues. Higher plateau modulus, longer relaxation time, and significantly higher zero-shear viscosity were noted for phosphonated ionomers by a dynamic melt rheology study. Compared to the ionic aggregates generated from sulfonate groups, larger ionic aggregates with associated phosphonate groups have been observed. Furthermore, phosphonated ionomers displayed significantly higher glass transition temperatures than sulfonated ionomers.
Ionomers have proven to be attractive, interfacially active compatibilizers for a number of polymer blend systems because of specific interactions that may develop between the ionic groups and complementary functional groups on other polar polymers within the blends. The successful compatibilization of polyester/polyamide blends (prepared by solution mixing and melt blending methods) using phosphonated PET ionomers as a minor-component compatibilizer has been demonstrated. The phase-separated polyamide domain dimension decreased with increasing mol % phosphonated monomers and this decrease was attributed to the specific interactions between the ionic phosphonate groups on the polyester ionomer and the amide linkages of polyamide. More importantly, the divalent phosphonate pendant ions are more effective at compatibilizing polyester/polyamide blends in comparison to the monovalent sulfonate pendant ions. Phosphonated PET ionomer-compatibilized polyester/polyamide blends required 6 times fewer ionic monomers to achieve domain dimension < 1 μm as compared to sulfonated PET-containing blends.
Deep eutectic solvents (DES) have been reported to be the next generation solvents due to the superior biocompatibility, biodegradability, and sustainability as compared to ionic liquids. Two types of deep eutectic solvents, choline chloride : malic acid (ChCl:MA) and L-arginine : levulinic acid (Arg:LA), have been demonstrated as effective plasticizers for poly(vinyl alcohol) (PVOH) films. The plasticization effects on the properties of PVOH films were evidenced by lower crystallizability and improved film ductility. In addition, ChCl:MA deep eutectic solvent was more effective in plasticizing PVOH as compared to propylene glycol, one of the most widely studied alcohol-type plasticizers. From an applied perspective, DES-plasticized PVOH film is a promising candidate in the packaging market of heath-related products.Doctor of Philosophy
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Hindawi, Iyad Ali. "Flow dependence of miscibility in polymer blends." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46820.
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Dittmer, Janke Jörn. "Dye/polymer blends for organic solar cells." Thesis, University of Cambridge, 2001. https://www.repository.cam.ac.uk/handle/1810/251783.
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Elliniadis, Stavros. "Phase separation in thermoplastic - thermoset polymer blends." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266360.
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Holloway, Matthew James. "Electrically conducting composites formed from polymer blends." Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316533.
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Chiou, Yung-Shi. "Local structural correlations in miscible polymer blends." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263072.
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Tavern, Sydney Christopher. "A spin-label study of polymer blends." Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320765.
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In the initial part of this study, electron spin resonance (ESR) spectra of polystyrene (PS) end-labelled with a nitroxide radical were recorded for both the pure polymer and for (1:1 w/w) blends with polyisoprene (PIP) containing varying amounts of PS-b-PIP triblock copolymer. The spectra reveal that the copolymer migrates to the interphase and that the rate of migration and final packing density of the copolymer in the interphase is dependent on the amount of copolymer in the blends. Further techniques were used to provide complementary data. The second part of this study examined the effect of preparation technique on the interfacial region in immiscible blends of PS with PIP and poly(methyl methacrylate) (PMMA) with poly (2-ethyl hexyl methacrylate) (PEHMA). Blends of these polymer pairs were prepared using the techniques of freeze-drying, co-precipitation and solvent-casting. ESR spectra of these blends recorded as a function of temperature, indicated that the freeze-dried blends exhibited significantly greater interaction between the labelled glassy components and the unlabelled rubbery components than either the co-precipitated or solvent-cast blends. These observations were interpreted on the basis that the average domain sizes of the rubber components within the blends is much smaller in the freeze-dried blends than in blends prepared by other methods, thus producing a relatively greater interphase volume. SEM micrographs of the blends supported this view. The final part of this study examines the local phase behaviour in the miscible polymer pair PS and poly (vinyl methyl ether) (PVME). ESR spectra of both nitroxide end-labelled and in-chain labelled PS were recorded for both the pure polymers and blends of varying composition with PVME. These blends initially form homogeneous, one phase systems followed by phase separation on heating. The results revealed that on phase separation polymer chain-ends tend to accumulate at the newly-formed interphase at the expense of inner chain segments. At temperatures below the cloudpoint slight plasticization of both inner and chain-end labelled PS occurs.
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Fernandez, Fernandez Maria Luisa. "Mixing and demixing studies in polymer blends." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47432.
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Bakhtiarian, Elaheh. "Synthesis and properties of conducting polymer blends." Thesis, Kingston University, 2014. http://eprints.kingston.ac.uk/28757/.
Full textAbstract:
Polymers and polymer-based composite materials with electrically-conductive properties are materials with various potential uses. Novel materials are becoming available in each field and new products are continuously being produced. Amid these new materials, conductive elastomers are presently being employed as antistatic materials in the carpets, antistatic coatings, sensors and electromagnetic screening. One promising method for making this type of material is to introduce carbon black or metal fillers, or more currently conducting polymer powders into natural or synthetic rubbers. Several polyaniline-rubber blends, mostly with poor electrical conductivity, have been reported in the literature. An important aim of this work was to improve the compatibility, thermal stability, electrical and mechanical properties of this kind of blend, produced by different mixing techniques for instance solution and thermo-mechanical with further methodical mixing processes and greater improved mixing circumstances. Polyepichlorohydrin, polychloroprene rubber, chlorosulfonated polyethylene rubber and polyaniline dodecylbenzenesulfonate (PAni-DBSA) were selected for study as blends in this project, since the solubility parameters of polyepichlorohydrin rubber, polychloroprene, chlorosulfonated polethylene and polyaniline dodecylbenzenesulfonate were calculated to be well-matched, and also because the polyepichlorohydrin rubber (PECH), polychloroprene rubber (PCR) and chlorosulfonated polyethylene (CSPE) were thermally stable and easily obtainable. No previous literature was discovered in relation to the electrical properties of the polyepichlorohydrin, polychloroprene or chlorosulfonated polyethylene blends with polyaniline dodecylbenzenesulfonate (PAni-DBSA). Hence, the PECH, PCR and CSPE rubbers were also chosen in this work with the purpose of studying them. Non-vulcanised PECH/P Ani-DBSA, non- vulcanised PCRlPAni-DBSA and non-vulcanised CSPEIPAni-DBSA blends with appropriate electrical conductivities were produced by solution mixing for the first time in this project. Blends of the PECH, PCR and CSPE rubbers and polyaniline doped with dodecylbenzenesulfonic acid, consisting of various proportions of P Ani- DBSA, were cast from solution onto polytetrafluoroethylene (PTFE) substrates with the aim of making electrically conductive films. Electrical conductivities of the cast films of non-vulcanised blends were calculated. Decomposition steps of electrical conductive polymer blends were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal stabilities of the PECHlPAni-DBSA, PCRJPAni-DBSA and CSPEIP Ani-DBSA blends were affected by the proportion of polyaniline dodecylbenzenesulfonate to the rubbers. The influence of composition on the glass transitions in the blends was defined by the use of thermomechanical analysis (TMA). Electrically conductive polymer blends of vulcanised PECHIPAni-DBSA were prepared by the use of an internal mixer for the first time. A remarkable agreement was seen in that both the vulcanised and the nonvulcanised blends had the electrical conductivities of the order of 10-8 S.cm-1 with approximately 20 wt% polyaniline dodecylbenzenesulfonate. The electrical conductivities of all the vulcanised PECHIP Ani-OBSA blends (with a conductivity percolation threshold 1 wt% or 1.07 vol % of P Ani-OBSA) were riot influenced by the addition of Zisnet-F as the vulcanizing agent. The ATIR spectra of vulcanised PECHIPAni-OBSA blends were similar to a superposition of the spectra of the pure vulcanised polyepichlorohydrin and pure polyaniline dodecylbenzenesulfonate, but with some distinctive peak shifts due to the changing intermolecular interactions among the PECH and PAni-OBSA polymers. The X-ray diffraction patterns of polyaniline dodecylbenzenesulfonate, the vulcanised pure polyepichlorhydrin and vulcanised polyepichlorhydrinl polyaniline dodecylbenzenesulfonate blend with 10% of PAni-OBSA were studied. The effects of addition of the polyaniline dodecylbenzenesulfonate on the morphology of the vulcanised PECHIP Ani-OBSA blends were evaluated by optical microscopy. The influence of orientation and alignment of the PAni-OBSA particles on the mechanical and electrical properties of vulcanised blends was investigated. The electrical conductivities of all vulcanised polyepichlorhydrin/polyaniline dodecylbenzenesulfonate blends were identified by stretching them. All vulcanised PECHIPAni-OBSA blends strained parallel to the flow direction when passed through the two roll-mills had their electrical conductivities improved with increasing strain in tension. A traveling microscope was used to investigate any possible dimensional change of samples versus applied voltage in order to define the effect of voltage to size change of the vulcanised blends. The electrical percolation threshold stage for the vulcanised PECHIP Ani-DBSA blends was studied. A tensile testing machine was employed to determine energy storage of each vulcanised PECH/P Ani-DBSA blend. Tensile property testing for the vulcanised polyepichlorhydrin /polyaniline dodecylbenzenesulfonate blends was accomplished according to the British Standards Institution (BS!) requirements in order to measure tensile strength, elongation at break and tensile modulus, and the samples all presented good mechanical properties. The stress-strain data of the vulcanised polyepichlorhydrin /polyaniline dodecylbenzenesulfonate blends have been analyzed and the crosslink density of them has been calculated. With good mechanical properties and reversible electrical behaviour, this kind of vulcanised blend may potentially be developed as a novel class of flexible smart material.
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Hawksworth, M. "The rheology of liquid crystal polymer blends." Thesis, Sheffield Hallam University, 1993. http://shura.shu.ac.uk/19773/.
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The present studies are concerned with the observation and explanation of the interaction between liquid crystal and isotropic polymers. An investigation of the rheological behaviour has been carried out on blends containing small additions of a main chain thermotropic liquid crystal polymers using capillary rheometry. Samples of these blends were moulded and tested using a Hounsfield tensometer and a Houndsfield swinging arm impact rig. The addition of a small amount of liquid crystal polymer was found to have a major effect upon both the rheological and morphological properties of the base material. This indicates the liquid crystal polymer can be used as a processing aid. A reduction of viscosity was noticed in all of the tests carried out and is attributed to the change in morphology induced by the addition of liquid crystal polymer. It would be of great benefit to the polymer processor if an understanding of the mechanisms involved could be highlighted. It is felt that the large interfacial area created between the binodal and spinodal has a bearing on the viscosity reduction. The morphology was different for material in the centre and the skin regions. The characteristic skin/core morphology was seen in all samples produced above a critical amount of liquid crystal polymer and temperature. The interaction between the liquid crystal polymer and the base material was explained using a model which predicted the velocity profiles given the shear rate, consistency constant and shear thinning index of the blends. The interface position is important because on one side of the interface the material is subject to elongational forces and compressive forces on the other. The elongational forces extend the LCP domains inducing an imposed morphology on the isotropic matrix. This could be seen in extruded and injection moulded samples, in the form of highly orientated surface skin layers. The orientation in the skin layers improved the barrier properties of the resultant blends, by allowing molecules in the surface layers to pack more closely together.
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Izumitani, Tatsuo. "Studies of Spinodal Decomposition of Polymer Blends." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149438.
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Clarke, Christopher John. "The structure and kinetics of formation of grafted polymer layers." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320014.
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Wilshaw, Claire Tamsin. "Directed phase separation of polymer blends on binary-patterned polymer brushes." Thesis, University of Sheffield, 2009. http://etheses.whiterose.ac.uk/573/.
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Self-assembly of well-defined polymer microstructures is of interest for applications such as polymer solar cells, light emitting diodes, microelectronics and biosensors. Chemically patterned substrates can direct the phase separation of thin films of polymer blends, producing controlled morphologies. This has been demonstrated using patterned self-assembled monolayers. Binary-patterned polymer brushes provide a robust, chemically and topographically patterned surface which can interact with the blend, potentially resulting in interesting new behaviour, and greater control over phase separation. Binary-patterned polystyrene/poly(methyl methacrylate) brushes were synthesised by a novel method. A self-assembled monolayer of triethoxysilane was patterned by exposure to ultraviolet light. This produced amine-terminated areas that could react with 2-bromoisobutyryl bromide to produce initiators for atom transfer radical polymerisation, allowing the synthesis of patterned polymer brushes. Dehalogenation of the first brush, followed by deprotection, modification and a second polymerisation produced binary-patterned brushes. Unpatterned and patterned polymer brushes were characterised using ellipsometry, x-ray photoelectron spectroscopy, contact angles, atomic force microscopy, lateral force microscopy, optical microscopy and secondary ion mass spectrometry. An alternative approach, based on direct microcontact printing of an atom transfer radical polymerisation initiator, 11-(2-bromo-2-methyl)propionyloxyundecyltrichlorosilane, was also investigated, although this approach was ultimately unsuccessful. The behaviour of thin films of polystyrene/poly(methyl methacrylate) blends on silicon, patterned self-assembled monolayers and binary-patterned polymer brushes was studied. The morphologies were investigated using atomic force microscopy, optical microscopy, nuclear reaction analysis and secondary ion mass spectrometry, in order to determine the effect of the binary-patterned polymer brushes on the domain structure of the blend. The blend morphology was complex and reflected interactions between the blend and the brushes (as well as other factors). When the natural length scale of the blend is commensurate with the underlying pattern, phase separation may be spatially directed by the substrate.
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Lindberg, Henrik. "Electron microscopy and microanalysis of polymers and polymer blends : artifacts and applications /." Luleå, 1986. http://epubl.luth.se/avslutade/0348-8373/57/index.html.
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Patel, R. "Compatibilisation by chain coupling agents: engineering polymers/thermotropic liquid crystalline polymer blends." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2005. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2453.
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Yang, Zhiyi. "Rheology of Miscible Polymer Blends with Hydrogen Bonding." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1184881292.
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Ruiz, Ilza Aparecida dos Santos. "Adição de EPDM ou anidrido maléico na blenda LDPE/PA6 e suas propriedades finais." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-11052009-133033/.
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Em virtude do crescente volume da utilização de embalagens multicamadas na preservação de alimentos, torna-se necessário o estudo visando a reciclagem desses materiais através de seu reaproveitamento como matéria-prima e a transformação em novos produtos ou materiais. Dentre os vários tipos de reciclagem utilizados atualmente, a formação de blendas poliméricas com material descartado apresenta-se como uma alternativa viável, pois se trata de uma atividade moderna que une o desenvolvimento tecnológico e a preservação ambiental. O presente trabalho faz um estudo sobre a reciclagem de resíduos de embalagens multicamadas pós-consumo no setor alimentício para a formação de uma blenda. O filme multicamada composto por poliamida 6 e polietileno de baixa densidade foi previamente moído para obtenção de flocos e a ele foi adicionado primeiramente o aditivo etileno-propileno-dieno monômero e em seguida foi feito uma nova mistura composta apenas de anidrido maléico com filme multicamada na forma de flocos, no intuito de melhorar as propriedades mecânicas das blendas formadas pelo processo da extrusão. Para a verificação dos resultados obtidos foram realizados testes de tração, alongamento e permeabilidade ao gás oxigênio no filme de poliamida 6 e polietileno, e ensaios mecânicos, análises térmicas e microscopia eletrônica de varredura nas blendas obtidas. Também se estudou o efeito da radiação (100 kGy) sobre as propriedades das blendas utilizando-se um acelerador de elétrons.In virtue of the increasing volume of the multilayers packings use in the food preservation, the study for the recycling of these materials through its reverse speed-exploitation as raw material and the transformation in new products or materials becomes necessary. Amongst some types of recycling used currently, the polymers blendes formation with discarded material is presented as a viable alternative, therefore if it deals with a modern activity that joins the technological development and the ambient preservation. The present research, therefore makes a study on the recycling of residues from multilayers packings after-consumes in the nourishing sector for the blend formation. The multilayer film composed by polyamide 6 and polyethylene of low density was previously worn out for flake attainment and it was added first the Ethylene-Propylene-Diene-Monomer (EPDM) additive and after that a new composed maleic anhydride mixture was made only with multilayer film in the flake form, in intention to improve the mechanical properties of blendes formed for the process of the drawing. For verification of the results assays had been carried through traction tests, rupture lengthening tests and permeability to the gas oxygen in the film of polyamide 6 and mechanical properties of blendes formed for the process of the drawing. For verification of the results assays had been carried through traction tests, rupture lengthening tests and permeability to the gas oxygen in the film of polyamide 6 and mechanical polyethylene, and assays, thermal analyses and scanning electronic microscopy in the blendes. It was also studied radiation dose (100 kGy) on the blends properties using an electron beam accelerator.
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Moilanen, A. (Anu). "Self-association, compatibility, and strengthening behavior of liquid crystalline oligomers." Doctoral thesis, University of Oulu, 1998. http://urn.fi/urn:isbn:9514250915.
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Abstract
Synthetic routes were developed for the preparation of 2-alkoxy-4-hydroxybenzoic
acids and 2-alkoxyhydroquinones, and a large-scale synthesis was
developed for the preparation of 2-thioalkoxyhydroquinones. The
2-alkoxy-4-hydroxybenzoic acids, which contained alkyl side chains of
different length, were used in the synthesis of new main chain liquid
crystalline (LC) homo-, random, and block co-oligomers. In addition,
oligomers of terephthaloyl chloride and 2-thioalkoxyhydroquinones
and oligomers of terephthaloyl chloride and 2-alkoxyhydroquinones
were produced.
All the oligomers were blended with aliphatic polyamide 11
(PA 11). The effect of alkyl side chain length on the compatibility
behavior of the LC oligomers towards the aliphatic polymer was characterized
by DSC and FTIR, and the effect of side chain length on the flexural
properties of the blends was investigated with a three-point bending
test.
The miscibility studies showed variable interfacial adhesion
between the blended compounds. The strongest adhesion was achieved
between PA 11 and the homo-oligomers of 2-alkoxy-4-hydroxybenzoic
acids with short or medium long substituents (C4-C10),
but the interactions between PA 11 and the oligomer with long aliphatic
side chain (C18) were poor, as were those
between PA 11 and the wholly aromatic oligomer of 4-hydroxybenzoic
acid. The compatibility between PA 11 and the co-oligomers of 2-alkoxy-4-hydroxybenzoic
acids was slightly lower than the compatibility of the corresponding
homo-oligomers. DSC and FTIR analyses of the blends of oligomers
of terephthaloyl chloride and 2-thioalkoxyhydroquinones and oligomers
of terephthaloyl chloride and 2-alkoxyhydroquinones with PA 11 implied
that the interactions between the blended compounds were poor.
FTIR spectra and viscosity measurements confirmed that all
the oligomeric structures could self-associate, with effect on the
final mechanical properties of the polyamide. The strength of PA
11 in a three-point bending test was increased by the addition of
only 1% of LC oligomers to the matrix. The results also
showed that the strengthening ability of the oligomers is directly
proportional to the total amount of aliphatic carbons. The best
strengthening results were obtained with unsubstituted oligomers,
random co-oligomers of 2-alkoxy-4-hydroxybenzoic acids, and homo-oligomer
of 2-butoxy-4-hydroxybenzoic acid.
DSC investigations of a ternary blend of the oligomer of 2-decanyloxy-4-hydroxybenzoic
acid, PA 11, and wholly aromatic commercial LC polymer showed the
promising compatibilizing effect of the oligomer.
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Rauschenberg, Nancy Carol. "Thermoplastic xylan derivatives and related blends." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-03172010-020606/.
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Leis, Paiva Felipe. "Interfacial behavior of Janus rods-stabilized immiscible polymer blends." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1593868264853478.
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Meller, Mika. "Dispersive mixing of high viscosity ratio polymer blends /." Lausanne, 2000. http://library.epfl.ch/theses/?nr=2267.
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