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Dissertations / Theses on the topic 'Copolymers and blends'
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1
Camiruaga, Elisa M. Elexpuru. "Miscibility studies of polymer blends involving acrylonitrile copolymers." Thesis, Heriot-Watt University, 1990. http://hdl.handle.net/10399/883.
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Wang, Haipeng 1968. "Characterisation of some dendritic polymers, copolymers, blends and nanocomposites." Monash University, School of Physics and Materials Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/8420.
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Arnold, Cynthia A. "Structure-property behavior of polyimide homopolymers, copolymers, and blends." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09162005-115012/.
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Ehtaiatkar, Fatemeh. "Structure - property relationship of block copolymers and their blends." Thesis, Brunel University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293177.
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Sagoo, P. S. "Vapour transport in natural rubber blends and graft copolymers." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37842.
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Zhou, Tingting. "Mechanical Analysis of Polycarbonate/Polysiloxane Block Copolymers and Blends." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26869.
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Polydimethylsiloxane (PDMS) can be used to react with polycarbonate (PC) to generate PC-PDMS multiblock copolymers and PC/PC-PDMS-PC triblock blends to overcome the notch sensitivity of PC while maintaining its transparency. It was found in this study that PDMS can act as a rubber particle to absorb energy and promote multicrazing. As a result, the incorporation of PDMS can increase PC's toughness. Meanwhile, high optical clarity can be observed even at 62 wt% PDMS in the multiblock copolymers with uniform morphology. However, PC/PC-PDMS-PC triblock blends damage PC's transparency and become opaque due to the phase separation. Furthermore, compared to compression molding, injection molding introduces shear due to the decrease of the area at the nozzle, which leads to the orientation of polymer chains and, subsequently, better properties of specimens.
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Minick, Jill Suzanne. "Microstructural analysis of polyethylenes and their blends and copolymers." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058204252.
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Chen, Quan. "Component Dynamics in Miscible Polymer Blends and Block Copolymers." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142180.
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Cheung, Zhuo-Lin. "Crystallization-driven surface segregation processes for polymer blends and copolymers /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CENG%202005%20CHEUNG.
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Ferrari, Federico. "Synthesis of Metal-Binding Ligand-Containing Copolymers, Nanoparticles and Blends." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19186/.
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In this thesis we developed three copper-containing systems.
Copper shows intriguing abilities in photocatalysis, however, one of the major limitations of many copper complexes is that photochemical properties might be quenched in solution caused by π-interactions between solvent and solute, due to Jahn-Teller distortion in the excited state.
As such, we herein seek to synthesise copper heteroleptic complexes that will subsequently be nanoprecipitated with a polymer. This will allow the polymer to encase the complex and prevent the solvent-induced quenching. Subsequently, the preparation of blends of polymer with the aforementioned copper complexes, at different weight ratios is sought.
The preparation of the blend is particularly interesting as the catalytic properties are anticipated to be inferior on account of the low surface area. However, owing to the polymer matrix better, mechanical properties are anticipated. The blends can combine the mechanical properties of the polymer and the luminescence of the complex, with the advantage that the polymer matrix can also prevent quenching from oxygen. As final task, we developed a copper-containing monomer. The synthesis of a monomer that contains copper and can be excited under ultraviolet (UV) light is particularly interesting.
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Brunacci, Antonio. "Physical aging in polymers, copolymers and blends of polystyrene derivatives." Thesis, Heriot-Watt University, 1995. http://hdl.handle.net/10399/1332.
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Chu, Jennifer Hsing-chung. "Phase behavior and binary interaction energies of copolymer blends /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Yau, Hon P. "Permeability of gases in copolymers, physical blends and composite particle materials." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282409.
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Wyatt, Mark Francis. "Analysis of acrylic polymers by MALDI-TOF mass spectrometry." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3962/.
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Poly(methyl methacrylate) (PMMA) homopolymers synthesised using 'classical' anionic methods and subsequently studied by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) are discussed. Specifically, the attempts at different end-group functionalisation reactions, their varying degrees of success, and the characterisation of these functionalized polymers via MALDI are reported. Extra peaks were observed in the spectra of samples containing a tertiary amine end-group. A mechanism for the in situ elimination of H(_2)(g) involving these end-groups, which would fit the observations, is proposed. Two alternative, 'non-classical' routes to the desired materials were investigated, as difficulties in successfully performing capping reactions to give end functionalised PMMA were noted. The first method was a variation of standard anionic polymerisation that involved the use of lithium silanolates, which could be performed at a higher temperature than normal. The second was a controlled free-radical technique known as Reversible Addition-Fragmentation Chain Transfer (RAFT). A lack of control of the polymerisation to the desired degree was observed with the former method. A well-defined RAFT sample was observed to undergo in situ eliminadon also, for which a mechanism involving the dithioester end-group is proposed, and which is supported by MALDI-collision induced dissociation (CID) evidence. The synthesis of block copolymers of various compositions of MMA with r-butyl methacrylate (t-BMA) and hexyl methacrylate (HMA), along with their homopolymers, and their subsequent characterisation is reported. PHMA was analysed easily, in contrast to Pt-BMA. Only copolymers with a high PMMA content were analysed successfully and this has been rationalised in terms of the factors that affect cationisation. The characterisation of equimolar blends of various end-functionalised PMMA samples is reported also. Samples that favour the binding of a metal ion over protonation appear to have a higher ion yield. Once more, these observations are rationalised in terms of the factors that affect cationisation.
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Janert, Philipp Klaus. "Phase behavior of homopolymer/diblock blends /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9763.
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Othman, Norhayani. "Rheology and processing of poly(lactides) and their enantiomeric copolymers and blends." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42697.
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Poly(lactide) PLA, a biodegradable thermoplastic produced from corn and other renewable agricultural resources, has received a large share of the interest in biodegradable materials due to environmental concerns and desire to reduce dependence on finite petroleum reserves. In this study, nearly monodisperse controlled microstructure PLA samples synthesized using a novel chiral dinuclear indium catalyst; and studied thermorheologically. Specifically, the effects of molecular structural parameters (i.e. weight-average molecular weight (Mw) and different ratios of lactides) on solution and melt rheological properties under shear and extension were studied. The solution properties and linear viscoelasticity (LVE) of melts indicated linear structure behavior. The zero-shear viscosity and relaxation time of PLAs showed a power law scaling of 3.4 with Mw. The K-BKZ constitutive equation was used and proved that strain hardening occurs at low temperatures, which is due to the dynamics of molecular relaxation, when the longest relaxation time exceeded the characteristic time for deformation.
In an attempt to reduce PLA brittleness, copolymers of L-lactide with its enantiomer D-lactide or racemic mixture DL-lactide were synthesized. The effects of Mw and block length ratio on the thermal, rheological and mechanical behavior of the diblock copolymers were investigated. For comparison, blends of PDLLA and PLLA homopolymers of equivalent Mw to the diblock copolymers were prepared. Despite different thermal behavior, the linear viscoelasticity of block copolymers and blends in disordered state are relatively similar. Improvement in elongation at break and tensile strength were observed as compared to their counterpart homopolymer blends.
Furthermore, the wall slip and melt fracture behaviors of four commercial PLAs with Mw in the range of 10⁴ to 10⁵ g/mol were investigated. PLAs with Mw greater than a certain value slipped. The slip velocity increased with decrease of Mw. The onset of melt fracture for the high Mw PLAs occurred at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Addition of 0.5 wt% of a poly(ε-caprolactone) (PCL) into the PLA that exhibits melt fracture was effective in eliminating and delaying its onset to higher shear rates.
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Harris, John Hills. "Miscibility windows in blends incorporating butadiene-acrylonitrile copolymers as the common component." Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/882.
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Fitzgerald, Annabel Victoria Lucy. "Preparation, characterisation and secondary crystallisation of PHB based copolymers and carbohydrate blends." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7474/.
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Poly(hydroxybutyrate) copolymers are sustainable and biodegradable, but they are known to exhibit secondary crystallisation, which severely reduces the ductility of these materials, thus hindering their current commercial use. Therefore, the main focus of this research was to explore a number of strategies to control the secondary crystallisation behaviour of two Poly(hydroxybutyrate) based copolymers. Blends of P(HB-co-HV)(3 wt % HV) with carbohydrate molecules of varying chain lengths were prepared by melt blending, characterised, and monitored over time to assess their capability to reduce secondary crystallisation. Additives were found to hinder the secondary crystallisation process, demonstrated by a reduction in the percentage change of mechanical properties as the concentration and chain length increased. The effect of storage temperature on the secondary crystallisation behaviour of P(HB-co-HHx)(33 % HHx) was also reported. Samples were stored at a range of storage temperatures and the effects on thermal, chemical and mechanical properties discussed. Increasing storage temperature caused the secondary process to occur to a greater extent, with greater increases in the melting temperature recorded in samples stored at 100 \(^∘\)C (128 \(^∘\)C - 135 \(^∘\)C) compared to samples stored at 7 \(^∘\)C (128 \(^∘\)C – 128 \(^∘\)C). Sub-melting point degradation of the material was also noted.
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Veith, Cary Alan. "New siloxane - nylon-6 diblock copolymers for emulsification and toughening of blends." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14336.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1989.Title as it appeared in MIT Graduate list, June, 1989: Siloxane-nylon-6 diblock copolymers for emulsification and toughening of blends.
Includes bibliographical references.
Cary Alan Veith.
Ph.D.
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Connell, James Grant. "Equilibrium and kinetic aspects of phase separation in polymer blends and diblock copolymers." Thesis, University of Strathclyde, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293239.
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Asafo-Adjei, Theodora. "SYNTHESIS AND CHARACTERIZATION OF POLY(SIMVASTATIN) - INCORPORATED COPOLYMERS AND BLENDS FOR BONE REGENERATION." UKnowledge, 2017. http://uknowledge.uky.edu/cbme_etds/46.
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Common biodegradable polyesters such as poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) and poly(ε-caprolactone) (PCL) are used as drug delivery vehicles for tissue regenerative applications. However, they are typically bioinert, with drug loading limitations. Polymerizing the active agent or precursor into its respective biodegradable polymer would control drug loading via molar ratios of drug to initiator used for synthesis. Simvastatin was chosen due to its favorable anti-inflammatory, angiogenic, and osteogenic properties. In addition, its lactone ring lends itself to ring-opening polymerization and, consequently, the synthesis of poly(simvastatin) with controlled simvastatin release.
Simvastatin was first polymerized with a 5kDa methyl-terminated poly(ethylene glycol) (mPEG) initiator and catalyzed via stannous octoate to form poly(simvastatin)-block-poly(ethylene glycol). Molecular weights ranged from 9.5kDa, with a polydispersity index (PDI) of 1.1 at 150 °C, to 75kDa with a PDI of 6.9 at 250 °C. First-order propagation rates were seen. Infrared spectroscopy showed carboxylic and methyl ether stretches unique to simvastatin and mPEG in the copolymer, respectively. Slow degradation was seen in neutral and alkaline conditions, with simvastatin, simvastatin-incorporated macromolecules, and mPEG identified as degradation products.
Alternatively, triazabicyclodecene (TBD) was used to mediate simvastatin polymerization. A lower temperature of 150°C led to successful polymerization using 5kDa mPEG, compared to at least 200 °C via stannous octoate. TBD was also successful for reactions using 2 or 0.55kDa mPEG. The biodegradability of poly(simvastatin)-block-poly(ethylene glycol) via TBD improved, losing twice more mass in phosphate-buffered saline, pH 7.4, than the copolymer synthesized via stannous octoate. Release rates of three different copolymers synthesized demonstrated tunable simvastatin release.
To further modulate degradation, poly(simvastatin)-block-poly(ethylene glycol) was blended with 5, 2, or 0.55kDa mPEG-initiated PLA copolymers. The blends showed a compressive elastic modulus ranging from 26 to 44MPa, within the magnitude of trabecular bone (approximately 50MPa). Tunability in mass loss and release was also seen due to varied ratios of incorporated PLA copolymers.
Lastly, copolymer degradation byproducts inhibited HMG-CoA reductase and showed possible enhancement of osteoblastic activity in vitro. A pilot study using a rodent calvarial onlay model showed tolerability of the polymers and potential for long-term evaluations of bioactivity. Poly(simvastatin) may be useful in regenerative applications.
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Adhikari, Rameshwar. "Correlations between molecular architecture, morphology and deformation behaviour of styrene, butadiene block copolymers and blends." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964298635.
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Kim, Yong-ju. "Phase behavior of disk-coil molecules : from bulk thermodynamics to blends with block copolymers." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81059.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 159-164).
In this thesis, we explore the phase behavior of discotic molecules in various circumstances. We first study the thermodynamics of disk-coil molecules. The system shows rich phase behavior as a function of the relative attractive strength of coils ([lambda]), the stacking interaction strength of disks ([mu]), the number of coarse-grained monomers of the coil (Nc), and the reduced temperature (T*). At high T*, a disordered phase is dominant. At intermediate T*, lamellar, perforated lamellar, and cylinder phases appear as y and Nc are increased. At low T*, disks crystallize into ordered lamellar, ordered perforated lamellar, and ordered cylinder phases. We find that the confinement imposed on the disks by the attached coils strongly contributes to the ordered stacking of the disks. In particular, the ordered cylinder phase contains highly ordered disks stacked in parallel due to the cylindrical confinement of the coils that restricts the system to a single degree of freedom associated with the director vector of the disks. Our results are important for understanding the self-assembly of supramolecular structures of disk-coil molecules that are ubiquitous in nature, such as chlorophyll molecules. Having established the importance of confinement on the phase behavior of discotic molecules, we next study blends of discotic molecules and block copolymers (BCPs) using self-consistent field theoretic simulations. In particular we explore systems containing a single sphere, rod, or discotic molecule confined within a BCP defect and systems containing multiple discotic molecules confined within BCP cylinders. In the former case, the sphere, rod, and discotic molecules are all trapped in the defect center where the cylinders of the surrounding BCPs make a junction. The director vector of the rod molecule aligns with the axial direction of one of the cylinders, while the director vector of the discotic molecule aligns perpendicular to the axes of all the cylinders. This preferential orientation is induced by the minimized stretching energy of the BCPs for these configurations. For the system with multiple discotic molecules confined within the BCP cylinders, all director vectors are aligned with the axial direction of the cylinder when the density of disks is high to minimize both the stretching energy of the BCPs and the polymer-mediated potential between the disks. These results provide design principles for next generation optoelectronic devices based on blends of discotic molecules and BCPs.
by YongJoo Kim.
Ph.D.
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Sugimura, Kazuki. "Comparative Studies on Miscibility and Intermolecular Interaction for Cellulose Ester Blends with Vinyl Copolymers." Kyoto University, 2015. http://hdl.handle.net/2433/200460.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19197号
農博第2136号
新制||農||1034(附属図書館)
学位論文||H27||N4943(農学部図書室)
32189
京都大学大学院農学研究科森林科学専攻
(主査)教授 西尾 嘉之, 教授 木村 恒久, 教授 髙野 俊幸
学位規則第4条第1項該当
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Cham, Pak-Meng. "Study of the miscibility, crystallization and morphology in poly(propylene) based blends and copolymers." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151359/.
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Bernard, Sophie. "Blends of a polystyrene-block-poly(ethylene oxide) copolymer and its corresponding homopolymers at the air-water interface." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0012780.
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Ma, Sungwon. "Nanostructures and properties of blends of homopolymer and elastomeric block copolymer nanoparticles." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34769.
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Nanostructures and properties of blends of homopolymer and elastomeric block copolymer nanoparticles were studied focusing on the effect of morphology and the viscoelastic properties on blends. The cylindrical and lamellar morphology of PS-b-PI copolymer was employed to generate the morphology of elastomeric nanoparticles such as nanofiber and nanosheet. The particles were synthesized using cold vulcanization process. The vulcanization process using sulfur monochloride (S2Cl2) was used to preserve the morphologies. The crosslinking density of block copolymer was controlled by exposure time of crosslinking agent in the chamber. The blend samples for DMA and rheometer were prepared using solvent casting process. The diameter and thickness of nanofiber and nanosheet obtained by the process were ~40 nm and ~70 nm, respectively. The rheological and dynamic mechanical properties of the blends of polystyrene (PS) and elastomeric nanoparticles were studied in terms of morphology and crosslinking density. The effect of core PI size also investigated and discussed. Based on these viscoelastic results, the theoretical percolation threshold was calculated and compared with experimental results. It is demonstrated that block copolymer is a facile method to generate elastomeric nanoparticles using cold vulcanization and viscoelastic properties can be tuned with addition of nanoparticles.
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Gong, Pengjian. "PHYSICAL FOAMING BEHAVIOR AT THE INTERFACE OF POLYMER BLENDS-Foaming Mechanism and its Application-." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180507.
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Schofield, Paula. "A study of poly(ethylene oxide) blends and copolymers in the presence of alkali metal salts." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260318.
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Tan, Kam Ho. "Synthesis and electrical properties of copolymers and blends of polyacetylene via poly(phenyl vinyl sulfoxide) precursor." HKBU Institutional Repository, 1992. http://repository.hkbu.edu.hk/etd_ra/16.
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Laghari, Gul Mohammad. "Preparation and properties of polybenzodioxane PIM-1 and its copolymers with poly(ethylene glycol)." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/preparation-and-properties-of-polybenzodioxane-pim1-and-its-copolymers-with-polyethylene-glycol(1b728ac9-9362-415d-ae6a-61dd3ffde884).html.
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This thesis describes the synthesis of soluble Polymer of Intrinsic Microporosity (PIM-1), fluoro-endcapped PIM-1 (F-PIM-1) and copolymers of F-PIM-1 with poly(ethylene glycol) monomethyl ether (MeOPEG). The main aim of the project was to alter the porosity of microporous PIM-1 in three ways: (a) synthesis of copolymers of F-PIM-1 with MeOPEG (b) blending of PIM-1 with MeOPEG in various proportions; and (c) adsorption of MeOPEG from aqueous solution byPIM-1. PIM-1 and F-PIM-1 were synthesized by step growth polymerization of tetrafluoroterephthalonitrile (TFTPN) with 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane (THSB), using the conventional method and a newly reported high shear mixing method. F-PIM-1 oligomers were then coupled to poly(ethylene glycol) monomethyl ether (MeOPEG). The products were analyzed by NMR, IR, MALDI ToF MSS, TGA and polystyrene based GPC as well as multidetector GPC techniques. The high shear technique generally produced high molar mass products and yields. This method was also more successful for copolymerization.Blending of PIM-1 and MeOPEG in different proportions resulted in macrophase separation. Copolymer products were used to facilitate mixing of blends (as compatibilizers), however only 5% of MeOPEG could be solubilised into a PIM-1 phase. The effect of compatibilizer was found to be affected by interaction between PIM-1 and copolymer. However, N2 adsorption studies showed that after thermal removal of MeOPEG, PIM-1 regained stable porosity with significant BET surface area.Fluorescence studies were aimed at applications of PIM-1 and copolymers in sensors. PIM-1 and copolymers, spin-coated on the polyester-based substrate Melinex, were studied with and without methanol treatment in an environment of different solvent vapours. The effect of time and volume on wavelength shift and change in intensity was studied. Polar solvents tended to cause a red shift with decrease in intensity while less polar solvents behaved otherwise. Based on fluorescence experiments, solvent profiles for PIM-1 and copolymers were established.
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Genoyer, Julie. "Compatibilization of PMMA/PS blends by nanoparticles and block copolymers : effect on morphology and interfacial relaxation phenomena." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10198/document.
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Ces travaux de thèse présentent une étude du mécanisme de compatibilisation induit par des nanoparticules d’argile dans les mélanges de polymères en utilisant la rhéologie. Pour cela, de la montmorillonite, la laponite et l’halloysite, modifiées ou non, ont été ajoutées à des mélanges PMMA/PS. Les résultats de rhéologie linéaire en cisaillement ont montré que le mécanisme de compatibilisation, particulièrement le phénomène de coalescence, dépendait beaucoup de la localisation des nanoparticules. La montmorillonite modifiée, présente à l’interface entre les polymères, est la plus efficace à inhiber la coalescence et est aussi efficace qu’un copolymère à bloc de haute masse molaire. Ceci est particulièrement intéressant car les nanoparticules d’argile représentent un coût moindre comparé aux copolymères à bloc. Dans ces travaux, une attention spéciale a été portée aux relaxations présentes dans les mélanges. En utilisant la rhéologie linéaire en cisaillement, un effet Marangoni a été mis en évidence pour la première fois dans le cas de nanoparticules d’argile modifiées présentes à l’interface. Enfin, les mélanges soumis à un flux élongationnel puis relaxation ont montré que la relaxation des gouttes de phase dispersée après une importante déformation était plus rapide par ajout d’argiles dispersées dans la matrice et ralentie par des argiles mieux dispersées soit à l’interface, soit dans l’ensemble du mélangeIn this thesis, the compatibilization mechanism induced by clay nanoparticles in polymer blends was investigated using rheology. To do so, montmorillonite, laponite and halloysite, modified or not, were added to PMMA/PS blends. Linear shear rheology showed that the compatibilization mechanism, especially the coalescence phenomenon, was greatly influenced by the localization of clay nanoparticles. Modified montmorillonite, which was located at the interface, was shown to be the most efficient at inhibiting coalescence among clays and as efficient as a block copolymer with a high molecular mass. The latter is particularly interesting as nanoparticles are cheaper than block copolymers. In this work, special attention was given to relaxations happening in blends. Using linear shear rheology, Marangoni stresses due to a gradient in compatibilizer concentration at the interface was evidenced for the first time in the case of organically modified clay nanoparticles when located at the interface. Finally, submitting blends to elongational flow and subsequent relaxation showed that the relaxation of the droplets after high deformations was faster in the case of clays dispersed in the matrix and slowed down by the interfacial tension in the case of a better dispersion of clays at the interface or in the whole blend
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SOUZA, Dayanne Diniz de. "Desenvolvimento de blendas de poliestireno/poli(ɛcaprolactona)." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1053.
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Capes
Blendas de poliestireno/poli(ɛ-caprolactona) (PS/PCL) foram obtidas em uma extrusora dupla rosca corrotacional e os corpos de prova moldados por injeção. O trabalho foi dividido em duas etapas. Na primeira etapa, as composições foram preparadas com adições de 25% em peso de PCL em duas matrizes de poliestireno com índices de fluidez diferentes (PS145D e PS158K). Na segunda etapa, três copolímeros com teores de 5% em peso foram adicionados à blenda PS/PCL com 25% de PCL. Os copolímeros utilizados foram: etileno-metacrilato de glicidila (EGMA), etileno-acrilato de metila-metacrilato de glicidila (EMA-GMA) e o estirenoetileno-butileno-estireno grafitizado com anidrido maléico (SEBS-g-MA). Os resultados mecânicos, termomecânicos e a morfologia da primeira etapa indicaram que as blendas PS/PCL são imiscíveis e incompatíveis, sugerindo a necessidade da adição de um compatibilizante que favoreça a adesão e o refinamento da fase dispersa na matriz polimérica. Foi observado que o poliestireno PS145D apresentou resultados favoráveis para a continuidade da pesquisa e a incorporação dos copolímeros. Os resultados obtidos na segunda etapa mostraram que os copolímeros E-GMA e EMA-GMA não foram eficientes na compatibilização da blenda, possivelmente devido a estes apresentarem interações apenas com a fase de PCL na mistura. O copolímero SEBS-g-MA atuou na interface da mistura PS/PCL, melhorando a miscibilidade e a compatibilidade da blenda, aumentando com isso a tenacidade à ruptura e resistência ao impacto do poliestireno.
Polystyrene/polycaprolactone) blends were obtained in a twin screw co-rotational extruder and injected. This study was divided into two stages. In the first step, compositions were prepared with additions of 25 %wt of the PCL two polystyrenes with different melt indices. In the second step, three copolymers were added the PS/PCL blend with 25%wt of PCL. The copolymers used were: ethylene-glycidyl methacrylate (E-GMA), ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) and styrene-ethylene-styrene grafted with maleic anhydride (SEBS-g-MA). The results mechanicals, thermomechanicals and morphology of the first step indicated that the PS/PCL blends are incompatibles and immiscibles, suggesting the need of adding a compatibilizer which promotes the adhesion and refinement of the dispersed phase in the polymer matrix. It was observed that polystyrene PS145D showed favorable results for continuity of the research and incorporation of the copolymers. The results obtained in the second step showed that the E-GMA and EMA-GMA copolymers were not effective in compatibilizing the blend, possibly due to these interactions only present PCL phase in the mixture. The SEBS-g-MA copolymer has acted on the interface of PS/PCL mixture, improving the miscibility and compatibility of the blend, thereby increasing the tenacity at break and impact resistance of polystyrene.
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Pantoja, Marcos. "Compounding and Processing Approaches for the Fabrication of Shape Memory Polymers." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555666527682024.
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Andrade, Marcela Fabbio. "Blendas cocontínuas de poliestireno e polipropileno : compatibilização, morfologia e propriedades mecânicas." reponame:Repositório Institucional da UFABC, 2016.
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Orientador: Prof. Dr. Danilo Justino CarastanDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2016.
Blendas de poliestireno e polipropileno foram preparadas em diferentes composições, com e sem a adição de compatibilizantes, para estudar e avaliar o grau de facilidade de obtenção de morfologia cocontínua, sua estabilidade morfológica e propriedades mecânicas. Os compatibilizantes utilizados foram copolímeros em bloco de poliestireno-b-poli(etileno-cobutileno)- b-poliestireno (SEBS) de três diferentes tipos, além de cargas nanoestruturadas, de partículas de sílica e argila. O grau de continuidade do poliestireno foi observado através da técnica de extração por solvente, a obtenção ou não da morfologia cocontínua foi observada por microscopia eletrônica de varredura, e sua estabilidade por caracterizações em microscopia ótica com o uso de platina de aquecimento. As propriedades mecânicas das blendas foram avaliadas por ensaios de tração, com o objetivo de verificar se a morfologia cocontínua e a adição dos compatibilizantes proporcionaram diferentes propriedades mecânicas às misturas obtidas. De fato, a adição dos compatibilizantes gerou uma certa estabilidade, influência no grau de continuidade além de facilitar a formação da morfologia cocontínua para algumas composições das blendas, porém não impediu completamente a ocorrência do efeito de coalescência. Para as composições limites, como 70/30 de PS/PP, os compatibilizantes SEBS 20 e a nanossílica R812 facilitaram a formação da morfologia, aumentando o intervalo de composições cocontínuas, além de conseguiram manter uma certa estabilidade da estrutura mesmo após o tempo de tratamento térmico. As cargas nanoestruturadas, conforme já previsto, interferiram nas propriedades mecânicas, aumentando a rigidez das blendas, independente da composição, sendo o oposto observado com os copolímeros, que por serem elastoméricos, aumentaram a flexibilidade das amostras.
Polystyrene and polypropylene blends over a wide composition range, with and without the addition of compatibilizers were prepared to study and evaluate the ease of obtaining a cocontinuous morphology, as well as their morphological stability and mechanical properties. Three different types of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers, as well as nanoclay and nanosilica were used as compatibilizers. The range of cocontinuity in the polymer blends was detected by the solvent extraction technique, and the type of morphology obtained was evaluated by scanning electron microscope (SEM). Annealing experiments were carried out to evaluate the stability of the blends by optical microscopy. The samples were submitted to tensile testing in order to evaluate the effect of the different types of morphology on the mechanical properties. The addition of compatibilizers was shown to create a certain stability in some compositions, however, the coarsening effect was not completely prevented. The presence of compatibilizers increased the range of cocontinuity and morphological stability in some compositions, such as 70/30 PS/PP. The nanoparticles, as expected, had an effect on the mechanical properties, increasing the stiffness of the blends, regardless of the composition, while the opposite was observed for the copolymers. Being elastomers, they increased the flexibility of the blends.
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Zhang, Wenrui. "Synthesis and Characterization of Toughened Thermally Rearranged Polymers, Poly(2,6-Dimethylphenylene-oxide) Based Copolymers and Polymer Blends for Gas Separation Membranes." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/86363.
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Thermally rearranged (TR) polymers have outstanding gas separation properties, but are limited in their industrial application due to being mechanically brittle. A series of low volume fraction of a poly(arylene ether sulfone) (PAES) block was introduced into the TR precursor polyhydroxyimide (PI) chain to improve mechanical properties without compromising gas transport properties. The multiblock copolyhydroxyimide incorporated the PAES in systematically varied amounts and copolymerized it with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 3,3’-dihydroxy-4,4’-diaminobiphenyl. Before thermal rearrangement, the PI-co-PAES precursors exhibited much more improved mechanical properties (tensile stress and strain at break) than those of homo polyimide precursor. After thermal rearrangement, tensile stress and strain at break of all TR copolymers decreased comparing to their corresponding precursors, but improved comparing to the homo TR polymer. Poly(phenylene oxide) (PPO) based copolymers (Chapter 4) and polymer blends (Chapter 5) were also studied for use as gas separation membranes. The polymer materials were cast into films, then crosslinked in the solid state with UV light. The ketone and benzylic methyl groups crosslinked upon exposure to UV light. For the study of PPO copolymers, copolymers were prepared by polycondensation of a difunctional PPO oligomer with 4,4’-difluorobenzophenone or 1,3-bis(4-fluorobenzoyl)benzene respectively. This study offers a means for fabrication of membrane films, fibers or composites, as well as tuning of gas transport properties through crosslinking in the solid state. While for the study of PPO polymer blends, PPO polymers with Mn’s from 2000-22,000 g/mole were synthesized and blended with a poly(arylene ether ketone) derived from bisphenol A and difluorobenzophenone (BPA-PAEK). The crosslinked blends had improved gas selectivities over their linear counterparts. The 90/10 wt/wt 22k PPO/BPA PAEK crosslinked blends gained the most O2/N2 selectivity and maintained a high permeability.Ph. D.
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Lei, Xia. "Blends of High Molecular Weight Poly(lactic acid) (PLA) with Copolymers of 2-bromo-3-hydroxypropionic Acid And Lactic Acid (PLB)." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367402061.
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Marinetti, Loris. "The effect of poly(lactide)-poly(carbonate) based block copolymers on the morphology and crystallization of double crystalline poly(lactide)/poly(ε-caprolactone) blends." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11965/.
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Block copolymers of poly(lactide) and poly(carbonate) were synthetized in three different compositions and characterized by 1H-NMR and ATR analyses. The compatibilization effect of this copolymers on 80/20 (w/w%) PLA/PCL blend was evaluated. SEM micrographs show that all the blends exhibit the typical sea-island morphology characteristic of immiscible blends with PCL finely dispersed in droplets on a PLA matrix. Upon the addiction of the copolymers a reduction on PCL droplets size is observable. At the same time, a Tg depression of the PLA phase is detected when the copolymers are added in the blend. These results indicate that these copolymers are effective as compatibilizers. The copolymer that acts as the best compatibilizer is the one characterized by the same amount of PLA and PC as repeating units. As result, in the blend containing this copolymer PLA phase exhibits the highest spherulitic growth rate. An analyses on PLA phase crystallization behaviour from the glassy state within the blends was evaluated by DSC experiments. Isothermal cold crystallization of the PLA phase is enhanced up an order of magnitude upon the blending with PCL. Annealing experiments demonstrated that the crystallization of the PCL phase induces the formation of active nuclei in PLA when cooled above cooled below Tg. When the crystallization rate of PCL is retarded, a reduction on PLA nucleation is observed.
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Arnett, Natalie Yolanda. "Synthesis and Characterization of Disulfonated Poly(Arylene Ether Sulfone) Random Copolymers as Multipurpose Membranes for Reverse Osmosis and Fuel Cell Applications." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26662.
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The results described in this dissertation focus on the synthesis and utilization of several disulfonated poly(arylene ether) random copolymer membranes in fuel cell and reverse osmosis applications. Poly(arylene ether)s were prepared by direct step copolymerization using a third monomer 3,3–-disulfonated 4,4–-dichlorodiphenylsulfone. The membrane properties of a 4,4–-biphenol-based disulfonated poly (arylene ether sulfone) random copolymer (BPS-35), optionally blended with various fluorine containing polymers or unsulfonated biphenol-based poly (arylene ether sulfone)s (Radel R) were investigated for fuel cell applications. Fluorine containing copolymers used included with 2,2–-hexafluoroisopropylidene 4,4–-biphenol based unsulfonated (6F-00) or disulfonated (6FS-35 and 6FS-60) PAES, hexafluoroisopropylidene biphenol based 4,4–-difluoro phenyl phosphine oxide) (6FPPO), and poly(vinylidene fluoride) (Kynar®). Tapping mode atomic force microscopy (TM-AFM) images of the membranes with 10 wt% of fluorinated copolymers showed macroscopic phase separation. Good miscibility between the copolymers at low concentrations was also confirmed by the observation of only one glass transition temperature. Compared to the benchmark Nafion 1135, the 10wt% blends of the fluorinated copolymers afforded a considerable reduction in the methanol permeabilities, which is important for direct methanol fuel cells (DMFC). The best DMFC performance with 0.5 M methanol fuel was illustrated with blends containing 10 wt% 6FS-00. At higher methanol concentrations (up to 2.0 M) BPS-35/6FS-00 (90/10) membranes outperformed both Nafion membranes.
Blends of BPS-35 blends with 6FS-35 or Radel R were also used as RO membranes. The highest salt rejections of 97.2 and 98.0% were obtained from BPS35/Radel R (90:10) and BPS-35/6FS-35 (95:5) blends, respectively in the salt form.
A systematic study of the preparation of BPS-20 random copolymer skin-core asymmetric membranes by diffusion induced phase separation (DIPS) from various polar aprotic solvent or cosolvent systems is reported. The best aprotic solvents to generate an asymmetric structure were NMP and DMAc whereas tetrahydrofuran (THF)/ formamide (FAm) (80/20 v/v) mixtures proved to be the best co-solvent systems. Acetone was the best non-solvent to prepare asymmetric membranes from both aprotic solvents and co-solvent mixtures. Overall, asymmetric membranes prepared from THF/FAm co-solvent mixtures illustrated the most stable phase separated morphology that was free of macrovoids. However, thicker skins (~5 μM) were formed due to the high volatility of THF. Therefore, ultra-thin skin thin film composites (TFC) based on BPS-20 in diethylene glycol (Di(EG) were prepared. Thermal treatment of these TFC was conducted at 90 °C and the addition of 20 wt% glycerin to the casting formulation helped to prevent pore collapse in the porous Udel polysulfone. A minimum of three coats was required to obtain a dense, smooth, and pinhole free skin layer. The generation of three dimensional (ternary) solubility parameter phase diagrams based on experimental data was formulated and a region of solubility based on the solubility parameters of the aprotic solvents and the different co-solvent systems was established for BPS-20.Ph. D.
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Costa, Nelson Rodrigo. "Desenvolvimento e caracterização em blendas formadas por copolimero de etileno-propileno e PAni dopada." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267062.
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Orientador: João Sinezio de Carvalho CamposDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A proposta deste trabalho é desenvolver um material de fácil processamento de é boa condutividade elétrica. O método de preparação escolhido foi o de solução dos polímeros escolhidos, PAni dopada com ADBS e do copolímero de etileno/propileno, num solvente comum (Xileno) com a subseqüente evaporação total do solvente. Caracterizou-se os efeitos da PAni/ADBS (10%, 20%, 40% e 50%), do EPR e do anidrido maléico (MAH) juntamente com o peróxido como compatibilizantes. A análise termogravimétrica mostra que as blendas desenvolvidas apresentam três fases de perda de massa, sendo a segunda a principal. O ADBS degrada no segundo estágio e por conseqüência desdopa a PAni. Além disto, revela que as blendas com 50% de PAni apresentam uma temperatura de degradação ao redor de 335 ºC, a qual é superior ao polímero puro (295ºC). Isto leva à suposição de uma parcial compatibilização do EPR com a PAni/ADBS. A hipótese volta a ser sustentada pela análise de DSC, onde a Tg é influência pela concentração de EPR. As blendas apresentam mais de uma Tg, apontando para a imiscibilidade, mas a Tg da fase rica em PAni/ADBS da blenda com 20% de PAni/ADBS é de 65ºC, enquanto que na blenda com 50% é de 54ºC, o que levanta a suposição de uma miscibilidade parcial. O MAH e o peróxido não influenciaram nos resultados das análises térmicas. Ao passo que, a técnica analítica de infravermelho não identificou mudanças vibracionais nas moléculas das blendas em estudo, não suportando a hipótese de miscibilidade mesma que parcial. As imagens de MEV mostram uma blenda imiscível e uma estrutura de placas que evolui com o aumento da concentração de PAni/ADBS. Nota-se também uma evolução diferenciada da fase PAni/ADBS nas blendas com MAH e peróxido, levando a uma hipótese que estes compostos devem influenciar na morfologia da fase PAni/ADBS. A avaliação da condutividade elétrica superficial das blendas mostra que ela é proporcional à concentração da PAni/ADBS e que as blendas com 50% de PANi/ADBS apresentam apenas uma década de diferença de condutividade em relação a PAni/ADBS pura. Com base nos resultados obtidos o processamento via solução mostra ser um método promissor, proporcionando blendas de alta estabilidade térmica e boa condutividade.
Abstract: The proposal of this work is to develop a new material, which is easy to process and it has a good electrical conductivity. The process method chosen was the solution of the polymers, doped polyaniline with dodecilbenzeno sulfonic acid and the ethylene/propylene copolymer, in a common solvent (Xylene), follow by casting. The effect of PAni/ADBS (10%, 20%, 40% and 50%), EPR, maleic anhydride and peroxide were characterized. The thermo gravimetric analyses showed that the blends have three steps of mass loss, among them the second is the more important. The DBSA degrades in the second step, consequently, desdopes the PAni. Besides, the TGA pointed out that the blend with 50% of PAni/DBSA has a temperature of degradation around 3350C, which is higher than the PAni/DBSA polymer (2950C). Based on that, the hypothesis of partial compatibilization between EPR and PAni/DBSA was raised. The DSC analyses supported this assumption (the Tg is influenced by EPR concentration). The blends have more than one Tg, indicanting that the blends are immiscible, but the Tg of the PAni/DBSA phase with 20% of PAni/DBSA is 650C, while the blend with 50% is 540C. The MAH and the peroxide did not influence the results of the thermo analyses. Regards to infrared spectroscopy analyses, the technique did not identify any change in the vibrations of molecule of the developed blends, thence it follows that the miscibility hypothesis, even partial, is not supported by infrared. The SEM photographs showed more than one phase and plates structures. These plates structures are influenced by the MAH and by the peroxide. Perhaps, these substances influence the morphology of PAni/DBSA phase. The superficial electrical conductivity of the blends is proportional to PAni/DBSA concentration and the blends with 50% of PAni/DBSA have only one decade of difference in relation to PAni/DBSA polymer.
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química
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Naylor, Andrew. "A supercritical route to copolymer blends." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436808.
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Nallapaneni, Asritha. "BIOMIMETIC NON-IRIDESCENT STRUCTURAL COLORATION VIA PHASE-SEPARATION OF COMPATIBILIZED POLYMER BLEND FILMS." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1590749223865508.
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Magaton, Marina. "Élaboration et caractérisation de nanocomposites à base de mélanges polystyrène/polyamide 6 et d'argile montmorillonite." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL072N/document.
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Ce travail concerne l’élaboration de nanocomposites à base de polystyrène/polyamide 6/argile montmorillonite (PS/PA6/MMT). Son but premier a été d’évaluer l’influence d’un copolymère polystyrène greffé polyamide 6 (PS-g-PA6), en tant qu’agent compatibilisant pour promouvoir une meilleure interaction PS-PA6, et son influence dans l’intercalation/exfoliation des argiles, d’une part ; évaluer les structures et les propriétés des nanocomposites obtenus. Deux sortes d’argile montmorillonite ayant différents modificateurs organiques, bien que cinq sortes de PS-g-PA6 contenant différentes quantités de PA6 et différentes masses molaires de greffés ont étés utilisés. Deux compositions de mélange PS/PA6 ont été préparées, 50/50 et 80/20 % en poids. Les quantités d’argile et de PS-g-PA6 utilisées dans les mélanges ont étés 5 et 3% en poids, respectivement. Les images obtenues par microscopie électronique à balayage (MEV) ont montré qu’une inversion de phase a lieu entre les deux compositions, sus les conditions de procédé utilisées, le PS étant la phase mineure à 50/50 %. Les images de MEV ont également révélé que les copolymères et l’argile ont un effet synergique dans la compatibilization des mélanges PS/PA6, dans les deux compositions. La capacité de compatibilization des copolymères est fortement affectée par ses masses molaires et ses quantités de PA6, que promeuvent différents degrés de nouvellement des chaines dans l’interface PS/PA6. De manière générale, les copolymères contenant une plus grande quantité de PA6, associés à l’argile qui meilleure itérât avec la PA6 présentaient des meilleures propriétésThis work aimed the preparation and characterization on polystyrene / polyamide 6 / montmorillonite clay (PS/PA6/MMT) nanocomposites. The goal was to evaluate the influence of the addition of polystyrene graft copolymer with polyamide 6 (PA6-g-PS) with potential to act as a coupling agent, promoting better interaction between PS and PA6, and to study the structures and properties of obtained nanocomposites. Two types of montmorillonite clay, organically modified with different modifiers, as well as five types of PS-g-PA6 copolymer, possessing different amounts of PA6 and grafts with different molecular weights, were employed. Two PS/PA6 blends compositions were prepared, 50/50 and 80/20 wt%. The chosen amount of clay and PS-g-PA6 were 5 and 3% by weight, respectively. Images obtained via scanning electron microscopy (SEM) showed a phase inversion occurring between the two compositions, being PS the dispersed phase in 50/50% composition. SEM images also showed that the addition of copolymers and clay have a synergistic effect on the compatibilization of the blends PS/PA6 in both compositions. The copolymers coalescence ability is strongly affected by their molecular weight and their amount of PA6, which provides different levels of folding of the chains at the interface PS-PA6.The best results were obtained in systems where it was added concomitantly clay and copolymer. Rheology and TEM results showed that the molecular weight of copolymers influence the interfacial tension in mixtures. In general, copolymers containing larger amounts of PA6, associated with clay that best interacts with PA6, showed the best results
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Staudinger, Ulrike. "Morphologie und Bruchverhalten von Block- und Multipfropfcopolymeren." Doctoral thesis, [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1187261828675-34703.
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Clough, Norman E. "Thermodynamics of ethylene-vinyl acetate copolymer blends." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5489/.
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The purpose of this study was to characterise the miscibility of several poly(ethylene-co-vinyl acetate), EVA, based polymer blends. EVA has many industrial applications and is often present as one of several polymeric components. Consequently, there is considerable interest in the thermodynamics of these blend systems. The thermodynamics of these blends was studied using several techniques: differential scanning calorimetry; phase contrast optical microscopy; small angle neutron scattering and wide angle X-ray scattering. Characterisation was also to include assessing the relative enthalpic and entropic thermodynamic contributions to the Rory-Huggins interaction parameter (%) of these blends. To determine the enthalpic interaction parameter, a "mixing calorimeter" was designed and constructed to measure accurately the "heat of mixing" values on blending these polymers. Free energy interaction parameters were determined from melting point depression and small angle neutron scattering measurements. In all the blends studied, the heat of mixing was endothermic and consequently, the enthalpic interaction parameters were positive i.e. unfavourable to miscibility. Miscibility in these blends can therefore only be achieved by a dominant entropic contribution, favourable to miscibility. Using phase contrast optical microscopy, both miscible and immiscible phase behaviour was observed in this series of blends. This shows good agreement with predictions of miscibility from heat of mixing, melting point and small angle neutron scattering measurements, based on the classical Flory-Huggins lattice theory. Wide angle X-ray scattering and differential scanning calorimetry results have associated miscible blends with crystallisation effects between the blend components. Small angle neutron scattering has been used to determine the concentration and temperature dependence of interaction parameters in a miscible blend. From these values the upper critical solution temperature (UCST) of the blend was predicted. The enthalpic contributions to these interaction parameters show good agreement with experimental values determined from heat of mixing measurements. It was concluded that the classical Flory-Huggins lattice theory (despite its many well documented Limitations) appears to be particularly suited to the thermodynamic characterisation of miscibility in these polymer blends.
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Watson, Linda M. "Miscibility studies in statistical copolymer and terpolymer blends." Thesis, Heriot-Watt University, 1994. http://hdl.handle.net/10399/1393.
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Park, Dongsik. "Self-Assembled Patterns of Block Copolymer/Homopolymer Blends." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1209071160.
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Giacobazzi, Greta. "Crystallization behaviour of poly(lactide) in immiscible blend with poly(ε-caprolactone), comparison with solution and melt-mixed blends." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14465/.
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Poly(ε-caprolactone)-poly(carbonate) based copolymers, both block and random, were synthetized and characterized by 1H-NMR spectroscopy. The copolymers have been tested as compatibilizers in 80/20 (w/w%) PLA/PCL blends prepared both by melt and solution mixing. The concentration of PCL-PC based copolymer added to the blends was 2 wt%. Compression moulded sheets and solvent cast films were evaluated by GPC (Gel Permeation Chromatography), TGA (Thermogravimetric Analysis), SEM (Scanning Electron Microscopy), PLOM (Polarized Light Optical Microscopy), DSC (Differential Scanning Calorimetry). The addition of the copolymers does not cause an increased miscibility in PLA-PCL phases since a reduction of PCL particles size is not detected in SEM micrographs. At the same time, upon copolymers addition PLA’s Tg value does not decrease in both melt and solution mixed blends. Copolymers addition causes a reduction of molecular weight in melt mixed blends. In particular, the random copolymer (PCL-ran-PC) causes the highest reduction molecular weight in melt mixed blend, since it is characterized by the lower thermal stability as shown in TGA analysis. As result, PLA phase within melt mixed blends containing PCL-PC based copolymers shows a higher tendency to crystallize during both isothermal and non-isothermal DSC experiments. The increased crystallization of PLA phase is attributed to an increase in spherulitic growth kinetics determined by PLOM analysis. Upon molecular weight reduction in melt mixed blends containing copolymers, PLA chains have a higher mobility resulting in an improved motion towards the growing crystal front.
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Zhang, Chao, Teruyoshi Mizutani, Kazue Kaneko, Tatsuo Mori, and Mitsugu Ishioka. "Space charge and conduction in LDPE-polypropylene copolymer blends." IEEE, 2001. http://hdl.handle.net/2237/7163.
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Lohfink, Günter Werner. "Morphology and permeability in extruded polypropyleneethylene vinyl-alcohol copolymer blends." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74639.
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Studies of the morphology of extruded polymer blend systems have shown that it is feasible to produce a laminar structure of an ethylene vinyl-alcohol copolymer (EVOH) dispersed phase in a polypropylene (PP) matrix phase. The laminar structure forms in the core of the extrudate when a slit die is incorporated into the extrusion process.Morphological studies, including a study of morphology development inside the die and studies of the effect of processing conditions on the morphology of the final product, revealed that the laminar structure is a result of die design. Processing conditions influence mainly the shape and dimensions of the laminar core region of the extrudate.
Oxygen permeation tests have shown that the blend exhibits lower oxygen permeability than pure PP, when EVOH is incorporated as a dispersed phase into the system. Oxygen transmission rates obtained with a blend system can be as low as those obtained with a multi-layer coextrusion product, although only at high EVOH concentrations. Comparison of experimental data with theoretical permeation predictions shows that, up to 20wt% EVOH, the reduction in oxygen transmission rate is only minor, and follows the prediction for a homogeneous system. At 25wt%, a considerable decrease in oxygen transmission rate is noticeable, and the trend for higher EVOH contents is towards the behavior of a multi-layer system.