Дисертації з теми "Polymerization induced phase separation"
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Oh, Junsuk. "Computational simulation and morphological analysis of polymerization-induced phase separation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0031/MQ64240.pdf.
Повний текст джерелаLuo, Xiaofan. "Polymerization induced phase separation (PIPS) in epoxy/poly([epsilon]-caprolactone) systems." online version, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1189443918.
Повний текст джерелаLuo, Xiaofan. "Polymerization Induced Phase Separation (PIPS) in Epoxy / Poly(ε-Caprolactone) Systems". Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1189443918.
Повний текст джерелаGao, Ziyao. "Study of Shape Memory Polymer Composites from Polymerization Induced Phase Separation Process." Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10681918.
Повний текст джерелаPolymer composites are taking the place of traditional materials in many fields. They are preferred in engineering structures due to the advantages in strength, stiffness, thermostability, corrosion resistance, and ductility at high temperatures. Study of PCL-based shape memory polymer composite can expand its application. And in order to fully understand SMP properties, a series of comprehensive testing is required.
Samples with different PCL percentages must be made by using a standard and optimized procedure to eliminate unwanted variables, and to ensure the amount of PCL in samples is the only variable.
The DSC test on the SMP samples shows that there are two transition phases. One is at 53 °C and indicated as PCL melting temperature; another one is at 138.5 °C, indicated to be the glass transition phase.
Shape memory behavior tests on the SMP samples show that the PCL-based polymer composite has significant shape recovery ability. The ability of recovery is proportional with the amount of PCL in the sample. And the recovery performance is shown in both strain and stress recovery.
The mechanical properties of SMP composite are determined by compression tests. Tests are performed on each specimen with different PCL percentages. The maximum compressive stress is higher in specimens that have a higher amount of PCL, and this result agrees with results from the shape memory test.
Finally, the SMP composites are observed with SEM. A unique globule structure is shown in the specimens regardless of their PCL percentages. This globule structure is totally different from the structure in pure epoxy. The reason for this difference is still unknown and needs to be determined with further research.
Lee, Jeongwoo. "Fabrication of polymer/metal oxide composites through polymerization-induced phase separation and characterization of their mechanical and electrochemical properties." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1446217264.
Повний текст джерелаElhaj, Ahmed. "Porous Polymeric Monoliths by Less Common Pathways : Preparation and Characterization." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-89322.
Повний текст джерелаVenkateshan, Karthik Johari G. P. "Polymerization and phase separation studies in liquids." *McMaster only, 2006.
Знайти повний текст джерелаJordan, Alexander Thomas. "Liquid phase plasma technology for inkjet separation." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47543.
Повний текст джерелаKulkarni, Amit. "Reaction induced phase-separation controlled by molecular topology.*." Cincinnati, Ohio : University of Cincinnati, 2004. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1108001435.
Повний текст джерелаMunshi, Imran. "Reaction-induced phase separation in modified epoxy resins." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493906.
Повний текст джерелаKULKARNI, AMIT S. "REACTION INDUCED PHASE-SEPARATION CONTROLLED BY MOLECULAR TOPOLOGY." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1108001435.
Повний текст джерелаTabatabaei, Fatemeh, and Gunter M. Schütz. "Nonequilibrium field-induced phase separation in single-file diffusion." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194414.
Повний текст джерелаTabatabaei, Fatemeh, and Gunter M. Schütz. "Nonequilibrium field-induced phase separation in single-file diffusion." Diffusion fundamentals 4 (2006) 5, S. 1-38, 2006. https://ul.qucosa.de/id/qucosa%3A14278.
Повний текст джерелаPark, Heungsup. "Toners for xerographic textile printing produced via thermally induced phase separation." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/10005.
Повний текст джерелаBatarseh, Melanie Turkett. "Formation of anisotropic hollow fiber membranes via thermally induced phase separation /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаGarg, Nandita. "Polymer shielded dye-affinity chromatography and temperature induced phase separation two strategies to simplify protein affinity separation processes /." Lund : Dept. of Biotechnology, Lund University, 1995. http://books.google.com/books?id=Qw5rAAAAMAAJ.
Повний текст джерелаYahata, Yoshikazu. "Extended Design of Concentrated-Polymer-Brush-Decorated Hybrid Nanoparticles and Their Use for Phase-Separation Control." Kyoto University, 2018. http://hdl.handle.net/2433/232486.
Повний текст джерелаMurase, Hiroki. "Flow-induced phase separation and crystallization in semidilute solutions of ultrahigh molecular weight polyethylene." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144863.
Повний текст джерелаRasouli, Tezangi Ghoncheh. "Structure and kinetics of pressure-induced phase separation in polyolefin solutions and its acoustic detection." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121396.
Повний текст джерелаCette thèse utilise la théorie et la simulation pour éclaircir les principes fondamentaux et les mécanismes clés qui déterminent la démixtion dans les solutions de polyoléfines compressibles et sa détection à l'aide de propagation de l'onde acoustique. La démixtion par séparation de phase induite par la pression et sa détection acoustique a des applications directes à la fabrication industrielle de polyéthylène sur la base de la procédure de polymérisation en solution, et est un domaine d'évolution dans la théorie des polymères thermodynamiques.Les deux modèles, mis en œuvre et analysés dans cette thèse pour la structure et la cinétique de séparation de phase induite par la pression dans les solutions de polymère compressible et sa détection acoustique, intègrent la masse totale, la masse des composants, la lancée avec l'équation Sanchez-Lacombe de l'Etat, les équations rhéologiques Newtonienne et Maxwelliennes et les équations généralisé de flux de Fick qui incluent la compressibilité. Le transport de la chaleur est également inclus dans la modélisation acoustique. Le premier stade à une dimension de la séparation de phase par l'induction de pression par la décomposition spinodale est analysé séquentiellement pour fluides non-visqueux, visqueux et fluides viscoélastiques compressibles afin d'élucider les fonctions de la dissipation visqueuse et l'élasticité de polymère. Les résultats de cette thèse révèlent le caractère unique de la décomposition spinodale compressible par le couplage de la densité et la concentration du polymère, ce qui donne lieu à un nouveau processus de décomposition acousto-spinodal. A faible compressibilité, les vagues stationnaires de densité se couplent avec la démixtion, donnant lieu à des modes spinodaux oscillatoires avec périodicités spatiales et temporelles; ces résultats ont été établis à l'aide des outils de systèmes dynamiques montrant la coexistence des points critiques stables et instables qui est la base de la dynamique et le chaos complexes. La cinétique de la démixtion diminue avec la compressibilité et la viscosité et augmente avec l'élasticité du polymère. La structure est analysée et validée par des calculs du facteur de structure. Les relations d'échelle pour la structure et la cinétique sont résumées afin de faciliter les applications pratiques futures.Un modèle linéaire de détection acoustique de la décomposition spinodale est formulé et implémenté par le calcul de l'effet d'augmentation de la proximité de la ligne spinodale dans un fluide visco-élasto-thermo-diffusionnel compressible stable sur la dépendance en fréquence de la vitesse de propagation et l'atténuation du son. La réponse acoustique généralise les modèles précédents par le couplage de viscoélasticité et le processus de diffusion qui change avec la diminution de pression vers la démixtion. Les signatures de la séparation de phase dans la vitesse de phase et l'atténuation sont établies.Les résultats de cette thèse établit qu'éventuellement, acousto-SD dans les solutions polymères compressibles intégrant des ondes de densité dans les processus de transfert de masse, offre de nouvelles pistes à préparer sur mesure les polymers microstructures, le traitement des polymères et la caractérisation des polymères acoustiques.
Kahrs, Catharina [Verfasser]. "Investigations on the formation of porous membranes during non-solvent induced phase separation / Catharina Kahrs." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/121436716X/34.
Повний текст джерелаGhanbar, H. "Fabrication of porous particulate scaffolds using electrohydrodynamics and thermally induced phase separation for biomedical engineering applications." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1460533/.
Повний текст джерелаNascimento, de Andrade Fabiana. "Effect of condensable materials during the gas phase polymerization of ethylene on supported catalysts." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1016/document.
Повний текст джерелаFluidized bed reactors (FBR) are the only commercially viable technology for the production of polyethylene in the gas phase since the polymerization is highly exothermic and the FBR is the only type of gas phase reactor that offers adequate possibilities of heat transfer. The highly exothermic nature of this polymerization effectively poses many problems for gas phase operation and can limit the production of a certain process. However, in recent years the fluidized bed processes have been improved with new technologies. In particular, the addition of inert (usually liquefied) hydrocarbons allows one to increase the amount of heat removed from the reactor. These compounds increase the heat capacity of the gas phase and, if injected in liquid form, also evaporate and thus absorb even more heat from the reaction medium efficiently. This is known as a condensed mode operation. In it, one uses compounds that can be liquefied in the recycle condenser, and which are called Induced Condensing Agents (ICA). The use of ICA is extremely important from an industrial point of view. The injection of ICA can have many different physical effects at the level of the growing polymer particles. For instance, adding these compounds can cause changes in solubility and other physical properties, which can facilitate the transport of ethylene and hydrogen to the active sites of the catalysts. It is thus very important that the physical phenomena related to the sorption equilibrium of the monomer(s) and other species from the gas phase to the polymer phase, and their diffusion on the polymer matrix at the active sites should be accounted for. In addition to having an effect on the kinetics, these phenomena can also impact the structure of the polymer molecules and consequently qualify the characteristics of the polymer. Identifying the behavior of these phenomena under process conditions and control variables of the hydrogen/ethylene ratio and the comonomer/ethylene ratio with ICA are central objectives of this study. A series of ethylene homo- and co-polymerizations in the gas phase were carried out using a commercial Ziegler-Natta catalyst in the presence of ICA (propane, n-pentane, and n-hexane). We investigated the effect of temperatures, the partial pressure of ICA, hydrogen, and comonomers on the behavior of the polymerization. It was found that adding ICA significantly increased the reaction rate and average molecular weights at a given temperature. It was also unexpectedly observed that increasing the reactor temperature in the presence of an ICA actually led to a decrease in the overall reaction rate. These results were attributed to the socalled cosolubility effect. In reactions in the presence of different hydrogen concentrations, for an ICA/C2 ratio much larger than the H2/C2 ratio, the effect of ICA on ethylene solubility can counteract the decrease in average molecular weight caused by the presence of hydrogen. The impact of ICA on the rates of copolymerization reactions is more pronounced in the initial stages, losing strength due to the effect of the comonomer. Finally, an evaluation of the kinetics of crystallization under isothermal conditions for mixtures of different ICA:HDPE concentrations showed that the crystallization time is significantly higher for systems rich in ICA than for dry polymer
Martinavičius, Andrius. "Structural and transport property changes in austenitic stainless steel induced by nitrogen incorporation." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-68719.
Повний текст джерелаLi, Chia-Ling. "Preparation of poly(vinylidene fluoride) (PVDF) membrane by nonsolvent-induced phase separation and investigation into its formation mechanism." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20155.
Повний текст джерелаThis dissertation shows how the morphology and polymorphism of poly(vinylidene fluoride) (PVDF) membranes prepared by using vapor-induced phase separation (VIPS) and liquid-induced phase separation (LIPS) were tuned by varying the dissolution temperature at which PVDF was dissolved (Tdis) to form the casting solution. We observed a transition temperature denoted by critical dissolution temperature, Tcri, across which the morphology and polymorphism of membranes (obtained by VIPS) drastically changed. The phenomenon was considered as general, as a Tcri was observed for all the three solvents N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF) and the non-solvents, water and a series of alcohols, used in the present study. No matter which Tdis we used, polymer crystallization occurred prior to the L-L demixing. With Tdis above Tcri, the prepared membranes were composed of nodules (mainly in beta crystalline form) and the size of polymer domains decreased as the Tdis decreased. Because the polymer chains could freely coarsen to a large domain during the phase separation, we called the system free coarsening. With Tdis below Tcri, membranes with lacy (bi-continuous) structure (mainly in alpha crystalline form) were obtained. Because the polymer solution gelled during the phase separation, we called the system hindered coarsening. It was proven that PVDF membrane morphology and crystalline polymorphs can be monitored by Tdis and the solvent-nonsolvent exchange rate. These results were discussed in terms of self-seeding effect and competition between the gelation, crystallisation and L-L demixing
Kim, Jae-Kyung. "Preparation of Porous Polymeric Materials by Phase Separation Induced in the Course of Drying a Ternary Polymer Blend Solution." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/124504.
Повний текст джерелаErikson, Pontus. "The Interaction of Oil and Polymer in the Microporous Polyethylene Film when using a Thermally Induced Phase Separation Process." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266155.
Повний текст джерелаBatteri separatorn är en komponent i det konventionella batteriet som länge har förbisetts. Bara för att den är en inaktiv komponent, betyder inte att den är mindre viktig för battericellens prestation. Trender idag pekar mot en enorm tillväxt inom elbils-industrin, och med det även litium-jon batteriseparatorns marknad. Det är för att litium-jon batteriet är det batteriet som vanligen används kommersiellt idag i elbilar. I en av de två stora industriella tillverkningsprocesserna används olja för att åstadkomma en porös film. Denna studie syftar på att utvärdera olika oljors interaktion med polymeren i denna tillverkningsprocess. Eftersom de flesta batteriseparator-industrier idag använder paraffinrik olja så testas oljor med olika mycket naftalensikt innehåll för att hitta korrelationer mellan oljornas egenskaper och kristalliniteten eller porositeten hos filmerna. Inga korrelationer för porositeten eller kristalliniteten kunde göras till oljornas egenskaper. Bilderna tagna med SEM var ej tillräckligt förstorade för att kunna studera vare sig porstorleken eller porstrukturen hos filmerna. För framtida studier rekommenderas att samla in mer data för att kunna utskilja ”outliers” i datan, för att erhålla mer korrekta värden. Metodiken måste även verifieras för att säkerställa att proceduren är reproducerbar. För att studera porerna och porstrukturen, borde en FE-SEM användas för att få mer förstorade bilder med bättre kvalité på filmernas yta.
VITRANO, Ilenia. "USO DI TECNICHE AVANZATE PER LA OTTIMIZZAZIONE STRUTTURALE E FUNZIONALE DI SCAFFOLD COMPOSITI POLIMERO-CARICA INORGANICA PER LA RIGENERAZIONE OSSEA." Doctoral thesis, Università degli Studi di Palermo, 2020. http://hdl.handle.net/10447/395408.
Повний текст джерелаWenning, Christian [Verfasser], Annette M. [Gutachter] Schmidt, and Marc C. [Gutachter] Leimenstoll. "Reaction-Induced Phase Separation of PPG/PEO/HDI based bi-Soft Segment Polyurethanes / Christian Wenning ; Gutachter: Annette M. Schmidt, Marc C. Leimenstoll." Köln : Universitäts- und Stadtbibliothek Köln, 2017. http://d-nb.info/1151638307/34.
Повний текст джерелаHanafia, Amira. "Étude des mécanismes interdépendants d’élaboration d’une membrane polymère sans solvant organique par une méthode originale de séparation de phase (TIPS-LCST), à partir d’un polymère biosourcé : l’hydroxypropylcellulose." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20045.
Повний текст джерелаPhase separation of polyer/solvent system is the most widespread industrial process to manufacture membranes. Large solvent quantity is usually used whatever the process, hence leading to environmental (coagulation and washing baths treatment) and health (industrial and plant safety) problems.This study focuses on the development of new porous membranes made from hydroxypropylcellulose (HPC), a water soluble polymer, avoiding the use of any organic solvent. Moreover, the thermo-sensitive character of this polymer, characterized by a Lower Critical Solution Temperature (LCST) in water of about 40 °C, enabled to design an original thermally induced phase separation process by temperature increase above the LCST. This study aims (i) to find the ideal polymer solution composition to produce insoluble HPC membrane, (ii) to approach and understand the link between phase separation mechanism by spinodal decomposition, crosslinkig reaction and water extraction by evaporation, (iii) characterize pure water permeability under pressure. On-line monitoring of phase sepration dynamics by phase contrast optical microscopy, crosslinking reaction by rheology and water evaporation by thermogravimetric analysis of the system HPC/water/cross-linking agent ± porogen (PEG200) allowed an understanding of simultaneous and related mechanisms occurring during elaboration (phase separation / cross-linking / water evaporation) and a correlation with HPC membrane morphologies and characteristics in relation with phase separation process parametres. Pure water permeability characterization demonstrated the efficiency of cross-linking and structural strength during several filtration cycles. Furthermore, it has been shown that water permeability of HPC membranes could be controlled in part by the temperature and the applied pressure
Yen, Chi. "Synthesis and Surface Modification of Nanoporous Poly(ε-caprolactone) Membrane for Biomedical Applications". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268074499.
Повний текст джерелаJiang, Wen. "Zwitterionic Separation Materials for Liquid Chromatography and Capillary Electrophoresis : Synthesis, Characterization and Application for Inorganic Ion and Biomolecule Separations." Doctoral thesis, Umeå : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-153.
Повний текст джерелаNkabyo, Henry Ane. "A study on the reversible photo-induced isomerisation of platinum(II) and palladium(II) complexes of the N,N-dialkyl-N’-acyl(aroyl)thioureas with reversed-phase HPLC separation from related rhodium(III), ruthenium(III) and iridium(III) complexes." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86773.
Повний текст джерелаLima, Juliana Aristeia de. "Comportamento de fases de soluções binarias e ternarias de poli(etileno-co-alcool vinilico), poli(metacrilato de metila) e dimetilformamida." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248789.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-12T12:37:28Z (GMT). No. of bitstreams: 1 Lima_JulianaAristeiade_D.pdf: 4425741 bytes, checksum: e0c47d6335f66cc31a0fe6e5ac1c0457 (MD5) Previous issue date: 2008
Resumo: Neste trabalho foram estudadas blendas de poli(etileno-co-álcool vinílico) (EVOH), um copolímero semicristalino que combina segmentos hidrofílicos e hidrofóbicos e poli(metacrilato de metila) (PMMA), um polímero amorfo e hidrofílico. As blendas de EVOH, com teor de etileno variando de 27 a 44 mol %, e PMMA foram preparadas por casting a partir de soluções em DMF, e por mistura mecânica em um mini-misturador, objetivando: i) avaliar o comportamento de fases e a morfologia das blendas, EVOH/PMMA, em função da composição das misturas, do teor de etileno nos copolímeros de EVOH e do método de preparação; ii) obter os diagramas de fases das soluções binárias, EVOH/DMF, e ternárias, EVOH/PMMA/DMF, através do processo de separação de fases induzido termicamente (TIPS). O comportamento de fases das blendas, EVOH/PMMA, foi estudado através de Calorimetria Diferencial de Varredura (DSC) e Análise Dinâmico-Mecânica (DMA). A morfologia das blendas foi investigada por Microscopia Eletrônica de Varredura (SEM). As blendas independentemente do modo de preparação e da composição são imiscíveis. Como conseqüência desta imiscibilidade, as temperaturas de fusão (Tf) e cristalização (Tc) não são afetadas pela presença de PMMA. A morfologia das blendas varia com a composição e método de preparação. As blendas obtidas pelo método mecânico são compactas, apresentando morfologia de fase dispersa em uma matriz, com inversão de fases em aproximadamente 50 % em massa de cada componente. As soluções binárias, EVOH/DMF, e ternárias, EVOH/PMMA/DMF, foram submetidas a ensaios para a determinação das temperaturas de turvamento (Tturv) por microscopia ótica, e de cristalização dinâmica (Tcd), por DSC. As soluções binárias apresentaram comportamento UCST (upper critical solution temperature), sendo que a separação de fases L-L ocorre a temperaturas superiores à separação de fases S-L. O modelo de interações binárias prevê que a curva de separação L-L para as soluções EVOH- 38/DMF esteja situada a temperaturas superiores em relação às soluções EVOH-32/DMF e indica que a separação de fases resulta da baixa afinidade entre segmentos hidrofóbicos do EVOH com os segmentos do polímero contendo hidroxila e com o solvente, DMF, concordando com os dados obtidos experimentalmente. Filmes de EVOH obtidos pela evaporação do solvente mostraram-se densos, sem a presença de poros. As soluções ternárias também apresentaram comportamento UCST, resultando em duas fases macroscópicas, F1 e F2, à temperatura ambiente. A composição destas fases foi determinada por Análise Termogravimétrica (TGA), e os resultados mostraram que uma das fases macroscópicas é rica em EVOH e outra fase é rica em PMMA. As blendas resultantes da secagem dos sistemas ternários apresentaram duas camadas: uma densa e rica em PMMA e outra porosa e rica em EVOH. A presença de PMMA foi decisiva à formação de estruturas porosas
Abstract: In this work blends of poly (ethylene-co-vinyl alcohol) (EVOH), a semicrystalline copolymer which combines hydrophobic and hydrophilic segments and poly (methyl methacrylate) (PMMA), an amorphous and hydrophilic polymer were studied. EVOH blends, with ethylene content ranging from 27 to 44 mol% and PMMA were prepared by casting from solutions in DMF, and by mixing into a mini-mixer, with the objective of: i) evaluate the phase behavior and the morphology of the blends, EVOH/PMMA, depending on the composition of mixtures, the ethylene contents in the copolymers of EVOH and the conditions of mixing; ii) obtain the phase diagrams of the binary and ternary solutions, EVOH/DMF and EVOH/PMMA/DMF, respectively, by the process of thermally induced phase separation (TIPS). The phase behavior of the blends, EVOH / PMMA, was investigated by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The morphology of the blends was investigated by Scanning Electron Microscopy (SEM). The blends independently of the method of preparation and of the composition are immiscible. As a result of immiscibility, the melting temperature (Tm) and the crystallization temperature (Tc) are not affected by the presence of PMMA. The morphology of the blends varies with the composition and with the method of preparation. The blends produced by the mechanical method is compact, showing morphology of dispersed phase in a matrix, with inversion of phases in about 50% by weight of each component. The binary solutions, EVOH-38/DMF and EVOH-32/DMF, were submitted to experiments to determine the cloud temperature (Tcloud) by optical microscopy, and the dynamic crystallization (Tcd), by DSC. The binary solutions show UCST behavior (upper critical solution temperature), and the L-L phase separation occurs at higher temperatures than the S-L phase separation. The binary interaction model provides the L-L line to the EVOH-38/DMF, solutions which was situated at higher temperatures than the EVOH-32/DMF solutions and indicates that the phase separation results from the low affinity between the hydrophobic segments of EVOH with the segments of the polymer containing hydroxyl and the solvent, DMF, which agrees with the data obtained experimentally. Films of EVOH obtained by the solvent evaporating seemed to be dense, without the presence of pores. The ternary solutions also had UCST behavior, resulting in two macroscopic phases, F1 and F2, at room temperature. The phase compositions were determined by Thermogravimetric Analysis (TGA), and the results showed that one of the macroscopic phases is rich in EVOH and the other phase is rich in PMMA. The blends resulting from drying of ternary systems had two layers: a dense and rich in PMMA and another porous and rich in EVOH. The presence of PMMA was crucial to the formation of porous structures
Doutorado
Físico-Química
Doutor em Ciências
Mourier, Élise. "Nano-structuration sous contraintes de polyuréthanes segmentés thermoplastiques." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10267.
Повний текст джерелаThermoplastic segmented polyurethanes are an important class of thermoplastic elastomers which cover a wide range of applications. These materials are multi-block copolymers composed of alternating “hard” and “soft” segments which are respectively below and above their glass transition temperature under ambient conditions. TPUs exhibit a twophase microstructure which arises from the thermodynamic incompatibility between the hard and soft segments. This microphase separation is often combined with the crystallization of either or both segments. The mechanical properties of these polymers will depend upon the overall multiblock length and the hard block sequence length and how they affect the material morphology. Our goal is to understand how the polyurethane final properties can be affected by the processing stresses (extrusion, injection…). In this scope, experiments were performed using a rheometer or an optical microscope coupled with a shearing hot stage. A preshear controlled treatment was applied and its effect on the material structuration was followed. These characterizations highlighted the enhancement of phase separation kinetics by the shear. For instance, for presheared samples, phase separation and/or crystallization of the hard segments occur ten times faster than for non-sheared ones. Moreover, SAXS experiments carried out on samples structured from several conditions illustrated perpendicular arrangements of crystalline domains perpendicularly to the flow direction. Finally, this particular morphology induced by shear modifies the materials final mechanical properties
Pierrot, François. "Polymérisation in-situ en milieu fondu et sous écoulement élongationnel pour l'élaboration de nouveaux matériaux." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE011/document.
Повний текст джерелаIn this work, binary and ternary reactive blends based on immiscible thermoplastic polymers PMMA,PE and PS were realized. The in-situ polymerization of the styrene, precursor of PS, was led by thermal self-polymerization or still thanks to radical initiator. Blends were realized in a mixer named RMX who generates mainly extensional flows known for their distributive and dispersive skill even if components have an important viscosity difference. Various methods of preparation and parameters of mixtures were tested. Morphology was evaluated by the analysis of electronic microscopy images.The average radiuses of the dispersed PS phase were compared with those observed in the literature. The smallest that we obtained have an average radius of 50 nm. Binary mixtures 90/10 %m with PS or PE and with a thermodur polyepoxide (MDEA/DGEBA) were also realized. The smallest spherical nodules that we obtained have an average radius of the order of 65 nm
Akbarzadeh, Rosa. "Developing Hierarchical Polymeric Scaffolds for Bone Tissue Engineering." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1376962498.
Повний текст джерелаArnett, 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.
Повний текст джерелаPh. D.
Michon, Marie-Laure. "Heterogeneous epoxy-amine networks from the dispersion of cross-linked polymer microparticles." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0018/document.
Повний текст джерелаThroughout this work, the influence of the addition of cross-linked polymer microparticles (CPMs) in epoxy-amine formulations on the kinetics, morphology and thermo-mechanical properties of the final networks have been investigated. First, an easy, robust and well-controlled protocol was developed to obtain a large range of CPM size, Tg and amine functionality. This protocol based on reaction induced phase separation via precipitation polymerization was also applied to different chemistries and water soluble epoxy pre-polymers showing the large possibilities of this method. The capacity of obtaining a good compatibility between the CPMs and the matrix was ensure by synthesizing the CPMs in excess of amino groups. The study of the remaining reactive amino groups on the CPMS was of great interest and therefore deeply investigated. The titration of the surface amine was performed by developing a new protocol that enabled the quantification of primary and secondary amines on CPMs. It was then highlighted that even though these cross-linked microparticles were not porous, amino groups are available into the core and can react with other molecules that are able to diffuse into the CPM core. It was shown that when CPMs were dispersed into epoxy-amine blends, the diffusion of monomers into the CPM core occurred but differently depending on the dispersion process. Indeed, using tetrahydrofuran as solvent to help for the dispersion increased the diffusion of DGEBA into the CPM core and changed the thermo-mechanical properties of the final network by modifying the stoichiometric ratio of the matrix. Same phenomenon was observed but less amplified when CPMs were mechanically dispersed in DGEBA. Regarding the dispersion of CPMs in the amine cross-linker, IPD, its complete absorption could be observed into the CPMs, leading then to the desorption of IPD to create the network. Thus, a very complex behavior of CPMs was highlighted in presence of monomers or/and solvent: swelling and diffusion phenomena that are dependent on a number of parameters such as temperature, CPM cross-link density, solubility parameters, etc. The intensity of those phenomena leads to a variety of behaviors when CPMs are added into an epoxy-amine formulation: (a) slight decrease of gel times and increase of conversion, (b) modification of glass transition temperature of the matrix
Klamser, Juliane Uta. "Transitions de phase en basse dimension à l’équilibre et hors d’équilibre." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS333.
Повний текст джерелаAlthough nature is three-dimensional, lower dimensional systems are often effectively realized offering fascinating new physics. The subject of this thesis is phase transitions in low dimensions, with its primary focus on non-equilibrium phases in two-dimensional active matter. Unlike passive systems, active particles are driven by energy injected at the microscopic scale from internal degrees of freedom resulting in an irreversible dynamics, often giving rise to macroscopic phases in striking contrast to equilibrium. A goal is to give a quantitative characterization of such non-equilibrium phases and to capture these in simplest realizations of active matter. The thesis explores two-dimensional self-propelled particles with isotropic pair-wise interactions. The dynamics (persistent kinetic Monte Carlo) is a variant of passive disks and different from well-known models of active matter. A full quantitative phase diagram is presented including motility induced phase separation (MIPS) as seen in other active systems. Additionally, the famous two-step melting scenario with the hexatic phase extends far from equilibrium. In this non-equilibrium scenario, the activity can melt a 2D solid and the melting lines remain separated from MIPS. The second part explores a frequently debated issue of the existence of phase transitions in classical one-dimensional models with short-range interactions at non-zero temperature. A widely shared misconception is that such transitions are not possible. A clear counterexample to this belief is given where non-analyticity in the free energy emerges from a new mechanism with a geometrical origin, which is then established on a rigorous ground
Marques, Rosalva dos Santos. "Comportamento de fases de soluções de poliolefinas funcionalizadas e implicação na obtenção de membranas pelo processo TIPS." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248781.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Neste trabalho, estudou-se o comportamento de fases de soluções binárias e ternárias de poliolefinas funcionalizadas com hidroxilas (EVOH) e ácido carboxílico (PEAA) nos solventes dimetilformamida e álcool benzílico. Utilizou-se EVOH contendo 27 e 44 mol % e PEAA contendo 80 mol % de etileno. As soluções exibem o comportamento de fases do tipo UCST, apresentando separações de fases líquido-líquido (L-L) e sólido-líquido (S-L). As temperaturas de separação de fases L-L e S-L, TL-L e TS-L, respectivamente, foram determinadas para soluções com diferentes composições por inspeção visual e por DSC, respectivamente. Enquanto TS-L para as soluções binárias de EVOH varia fortemente da com a composição das soluções binárias, TS-L para as soluções binárias de PEAA é praticamente constante. Estes resultados foram interpretados sob a ótica de um modelo em que a cristalização do PEAA, que envolve os segmentos de etileno do copolímero, ocorre quase na ausência de solvente. Já a cristalização do EVOH, que envolve os segmentos hidroxilados, ocorre em meio ao solvente, em uma condição em que o potencial químico do polímero varia com a composição da solução. Este modelo pode ser comprovado por estudos de fluorescência empregando-se o pireno e o acetato de uranila como sondas hidrofóbica e hidrofílica, respectivamente. Estes estudos de fluorescência permitiram também acessar transições não detectáveis por DSC. As soluções ternárias homogêneas apresentam mais de uma separação de fases L-L quando submetidas a resfriamento. O diagrama de fases ternário foi construído determinando-se as composições das soluções em equilíbrio, decorrentes da primeira separação de fases L-L, por termogravimetria de alta resolução. Os diagramas de fases das soluções ternárias resultantes das combinações possíveis entre os diferentes polímeros e solventes apresentam regiões de miscibilidade limitadas localizadas em regiões próximas aos vértices, sendo as composições das fases em equilíbrio características de cada combinação nas soluções ternárias. Os materiais resultantes da evaporação do solvente de soluções submetidas ao processo TIPS (Temperature Induced Phase Separation) são compactos ou porosos, dependendo da afinidade polímero-solvente. Entretanto, as morfologias dos materiais resultantes de soluções ternárias submetidas ao processo TIPS são únicas e características do par polímero-polímero, demonstrando que a estratégia de combinação de polímeros para controlar a morfologia é viável
Abstract: The phase behavior of binary and ternary solutions of functionalized poliolefins with hydroxyls (EVOH) and carboxylic acid (PEAA) were studied using dimethylformamide and benzyl alcohol as solvents. PEAA containing 80 mol % and EVOH containing 27 and 44 mol % of ethylene were used. The binary and ternary solutions present a typical UCST behavior associated to liquid-liquid (L-L) and solid-liquid (S-L) phase separation. The temperatures related to L-L and S-L phase separation, TL-L e TS-L, respectively, were determined visually and using DSC, respectively. While TS-L depends on the EVOH solution composition, it is practically constant for PEAA solutions. These results were explained using a model in which the crystallization of PEAA from the solution occurs in absence of solvent, once it involves the polyethylene segments. On the contrary, the crystallization of EVOH from the solution, that involves the hydroxylated segments, occurs in presence of the solvent. This condition leads to the decrease of the chemical potential of EVOH in the solution. The models could be proved by fluorescence experiments using pyrene and uranyl acetate as hydrophobic and hydrophilic probes, respectively. Moreover, the fluorescence experiments allow accessing other transitions not detectable by DSC for ternary solutions. The homogeneous ternary solutions present more than one L-L phase separation by cooling. The ternary diagram was determined by the first L-L phase separation using the composition data accessed by high resolution thermogravimetry. The ternary solutions of all possible combination of polymers and solvents show a restricted miscibility window in the regions near the vertices. The composition of the phases in equilibrium is characteristic of each ternary solution, as well as, the morphology of the materials resulting from the evaporation of the solvent after the solution being subjected to TIPS (Temperature Induced Phase Separation) process. This process applied to binary and ternary solutions resulted in dense or porous materials depending on the polymer-solvent affinity. However, the morphology resulting from ternary solutions subjected to TIPS process and solvent evaporation is unique, showing that the strategy of combining different polymers is a viable route to control the morphology of polymers
Doutorado
Físico-Química
Doutora em Ciências
Ly, Hai Bang. "Matériaux polymères fonctionnalisés à double porosité : conception et modélisation." Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1144/document.
Повний текст джерелаPolymer-based porous materials have been the subject of intense research for many years and present some important advantages over their inorganic counterparts, such as tunable mechanical properties, ease to be functionalized, and especially lower production cost. Over the last decade, materials with dual porosity have attracted a particular attention from the scientific community, as these peculiar materials offer new interesting perspectives for engineering sustainable materials. The role of each porosity level is different and associated with distinct mass transfer processes. Macropores (~100 µm) would allow macromolecules and cells flow through the material, while a nanoporous network (10-100 nm) would be dedicated to the passage of smaller molecules, thus acting as a second transport mechanism, especially when macropores are totally clogged. The first part of this work addresses the development of versatile and effective approaches to biocompatible doubly porous poly(2-hydroxyethyl methacrylate) (PHEMA)-based materials. The first approach relied on the use of two distinct types of porogen templates, i.e. a macroporogen and a nanoporogen. To generate the macroporosity, either NaCl particles or PMMA beads that could be fused or not, were used in order to control the pore morphology and interconnectivity of the materials. The nanoporosity was obtained by using various amounts of different porogenic solvents, thus generating a wide range of pore size distributions for this second porosity level. The second methodology was based on the thermally-induced phase separation process. A co-solvent mixture constituted of dioxane and water was used to solubilize previously prepared linear PHEMA, followed by a solidification process by freezing the co-solvents/PHEMA mixture, and subsequent sublimation of the co-solvents to generate the corresponding biporous PHEMA materials. Finally, advantage of doubly porous materials was taken through different functionalization reactions using carbonyldiimidazole chemistry, and further immobilization of in-situ generated gold nanoparticles. Such hybrid doubly porous materials proved to act as efficient catalytic supports. In the second part, we numerically determined the permeability of doubly porous materials. The methodology was based on a double upscaling approach in the field of periodic homogenization theories and on unit cell calculations. The first upscaling consisted in the determination of a first permeability associated with the array of nanoscopic pores. At this scale, the pores were saturated by a viscous fluid obeying the Stokes equations and the problem was solved by means of standard Finite-Element approaches or using more recent techniques based on Fast Fourier Transform. At the mesoscopic scale, the fluid flow obeyed the Stokes equations in the macropores and the Darcy equations in the permeable solid. The unit cell problem coupling Darcy and Stokes equations was solved by the Finite Element method in order to compute the final macroscopic permeability. To this purpose, we developed a method based on a mixed variational formulation which was implemented by taking different elements in the solid and fluid regions. Various 2D and 3D examples were provided to illustrate the accuracy and the capacity of the proposed numerical methods to compute the macroscopic permeability of biporous materials
Pecher, Heike Susanne. "Entwicklung von Monolithen auf Basis polyfunktioneller Glycidylether für die Anwendung in der Affinitätschromatographie." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16933.
Повний текст джерелаMonolithic supports have been developed since 20 years and have become an attractive alternative to well-established columns packed with particles over the past years. They are classified into inorganic media and organic polymer monoliths. Monoliths consist of a single, continuous piece with an integrated characteristic porous network through which the eluent can flow with lower hydraulic resistance and which consequently offers higher flow rates. Due to an accelerated mass transfer caused by convection polymer monoliths are mainly used for separation of large biomolecules. In addition, they are stable over a wide pH range and can be polymerized directly (in situ) in the desired format. In the present work the successful preparation of new epoxide-based supports according to a concept introduced by Weller et al. as well as their application in affinity chromatography are reported. Their preparation was carried out by self-polymerization of polyfunctional glycidyl ethers and for functionalization non-polymerized epoxide groups were used. As monomers TEPIC, GE 100 and GE 500 were utilized. The work has focused especially on the polymerization of the higher functional GE 500, which can be perfomed at room temperature and was optimized in terms of both composition and amount of porogen. The extraction of IgG from rabbit serum with a capillary column (66 %, 12 µm, 7m2/g) prepared by 75 vol.-% porogen (dioxane/ MTBE (2:3)) and functionalized with rprotein A resulted in a capacity of 0,44 mg/mL. By addition of 60 % BDE the epoxide content was quadrupled and the pore size reduced to 400 nm while maintaining consistently high porosity of 59 %. The specific surface area was tripled and the capacity of prepared disks approximately doubled to 0,90 mg/mL. The disks developed in this work can be applied for the isolation of IgG from complex samples such as serum.
Chiang, Wen-Pang, and 江文邦. "Preparation of Porous Membranes by Polymerization Induced Phase Separation: Control of Surface Morphology." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65552294954528519853.
Повний текст джерела國立臺北科技大學
化學工程系碩士班
92
Membranes with porous structure were prepared by polymerization induced phase separation. The surface morphology of membranes can be tailored by choice of the various contact films. In this study the porous membranes were made of stepwise polymerization of a mixture of bisphenol-A epoxy resin(DER-331), long chain polyglycol diepoxide resin(DER-732), and curing agent, diethylenetriamine(DETA), in various solvents, such as 2,6-dimethyl-4-heptanone, cyclohexanol, and cyclohexane. The surface morphology of membranes was observed by a SEM. In the SEM micrographs it is demonstrated that surface morphology of membranes can be tailored by the contact films. The pore size of the membrane surface increases with decreasing the wettability between the monomer solution and the contact films. However, it was found that in a lower wettability between monomer solution and contact film, the surface pore size of the membrane decreases. The porous morphology inside of membrane is controlled by the volume percentage of solvent. The pore size increases with increasing the amount of solvent. Furthermore, the porous membranes were made of photo-chemically initiated polymerization of a mixture of methacry acid(MAA), ethylene glycol dimethacrylate(EDMA), and tripropylene glycol diacrylate (TPGDA)in various solvents, such as toluene, and 2-butanol. The surface morphology of membranes was observed by a SEM. The morphology of the membrane can be also tailored by different contact films pressed on the casting solution. It was found that the diffusion coefficient of the caffeine in the membrane increases with the surface porosity, while the equilibrium of sorption capacity is controlled by the bulk porosity of membrane.
Jana, Rounak. "Polymerizable Porogen – Direct generation of internally functionalized porous polymers." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5839.
Повний текст джерелаCSIR NET
Huang, Nan-Du, and 黃南都. "Study on Chemically Induced Phase Separation." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/888n7k.
Повний текст джерела國立臺北科技大學
化學工程所
93
Membranes with porous structure were formed by polymerization induced phase separation. In this study, the porous membranes were made of stepwise polymerization of a mixture of bisphenol-A epoxy resin (D.E.R. 331), polyglycol diepoxide resin (D.E.R. 732), and curing agent, diethylenetriamine (DETA), in different porogen. The surface morphology of membranes was observed by a SEM. It was found that the surface morphology of membrane is changed with the contact films. First, the pore size of the membrane surface increases with decreasing the wetting between the monomer solution and the contact films. However, the curing solution covered by a film with very low wet ability, such as Teflon, a dense skin or smaller pores formed during cure. The morphology of the membrane is also dependent on the ratio of D.E.R 732. The cloud-point profiles changed with the epoxy conversion at various temperatures were determined by a DSC and a microscope coupled with a UV-Vis spectrometer. The conversion of cloud-point increases with the curing temperature.
王偉弘. "Microporous Membrane Formation via Thermally Induced Phase Separation." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/01744743760511800226.
Повний текст джерела長庚大學
化學工程研究所
86
Thermally induced phase separation (TIPS) of polymer solutions is a commonly used technique to prepare microcellular foams or membranes with controlled morphologies. In this study, light scattering have been used to study morphology development in PC membrane formed by thermal inversion method. Cloud point was determined by transmittance and differential scanning calorimetry. Analysis of the early stage behavior of scattered intensity in terms of Cahn Hilliard theory established spinodal decomposition as the mechanism of phase separation for the conditions studied. Standard Cahn-Hilliard analysis predicts that the intensity at a given wavenumber should grow exponentially with time. For the same annealing time, the domain size increases with decreasing quench temperature. Consistent with our results, other light-scattering studies of polymer solution showed that the position of the initial intensity maximum increased as the quench temperature was decreased. However, the electron microscopy data of Song and Torkelson showed the reverse trend. All of the quenches reported in the study were to regions of phase diagram where the concentrated phase that formed was quite close to its glass transition temperature. As the phase separation temperature was lowered, the polymer-rich phase was expected to be closer to its glass transition temperature where the mobility would drastically lower. This decrease in mobility was believed to be the main factor thatθmax would not change in the later stage.
Chan, Hung-Yi, and 詹弘毅. "Producing metal foams by pressure-induced phase separation." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/05741917512158726661.
Повний текст джерела義守大學
材料科學與工程學系
89
The purpose of this study is to employ the technique of PIPS (pressure-induced phase separation) in foaming metallic alloys. The effects of the temperature of the molten metal, the gas pressure, and the various kinds of gases on the density and the microstructure of the solidified metal are investigated. The metal sample is loaded into a high-pressure furnace, which could be optionally made of stainless tube, hot press, or pressure vessel, and heated up to their solidus. In the meanwhile, either the pressurized carbon dioxide or hydrogen gas is purged into the high-pressure furnace. After the molten metal is hold at the designed pressure and temperature for one hour, the gas in the furnace is rapidly depressurized. Then, the alloy is quenched into in cold water to study the feasibility in the production of metal foam by the PIPS. It is presumed that the bubbles, created after depressurization, in the liquid molten stops growing within five seconds. It is found that extending the growing time leads to bubble’s merge and collapse and/or drainage, which results in the decrease of the density of the solidified alloys. When carbon dioxide is applied to Pb-Sn alloy at 180℃, the number and the size of the bubbles increases and the density of the solidified alloys decreases while the gas pressure increased from 100 to 300bar. It is presumed that the solubility of carbon dioxide in the molten alloys increases with gas pressure. However, the change of density, bubble size, and number of bubble with gas pressure at 190℃ is not significant as that found in 180℃. This temperature effect needs further study. From their microstructure observed in SEM, it is found that much of the bubbles is located in the Tin-rich phase. It is presumed that the interaction between carbon dioxide and Tin is much stronger than that of Lead. When hydrogen is applied to Pb-Sn alloy at 205 and 210℃, the density of the solidified alloys is not affected by the gas pressure in the range of 2 to 10bar, and no significant bubbles is observed in their microstructure. It is presumed that the solubility of hydrogen gas in this pressure range is too low to create significant number of gas bubbles in the molten metal. This is confirmed by replacing Pb-Sn alloy by Zinc alloy, which also shows that the density of Zinc alloy is not affected by the pressure of the hydrogen gas in the same range of pressure. Interestingly, it is observed that the size of the eutectic structure of the Zinc alloy decreases while the pressure of the hydrogen gas increases. This observation is worth further study.
Becker, Christian Guy. "Cure shrinkage control in polymerization of multicomponent resin systems with phase separation." Thesis, 1993. http://hdl.handle.net/1911/13691.
Повний текст джерелаWu, Jia-Yuan, and 吳嘉原. "Adhesion-induced Phase Separation ofBiomembranes—Effective Potential and Simulations." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/7k8zf8.
Повний текст джерела國立中央大學
物理研究所
94
We present theoretical analyses and numerical simulations for the adhesion-induced phase separation of multi-component membranes with two types of ligand-receptor complexes (junctions). We show that after integrating all possible distributions of the junctions, the system can be regarded as a membrane under an effective external potential. Mean field theory and Gaussian approximation are used to analyze the effective membrane potential and we find (i) The height difference of the junctions is the main factor that drives phase separation at sufficiently large junction height difference. (ii) In the two phase region far from the mean-field critical point, because of the higher entropy associated with the softer junctions, phase coexistence occurs when the effective binding energy of the more rigid junctions is higher. (iii) In the two phase region near the mean-field critical point, the shape of the effective potential shows that the phase coexistence occurs when the effective binding energy of softer junctions is higher. The effect of junction density on the critical point is studied by Monte Carlo simulations, and the result shows that phase separation occurs at larger junction height difference as junction density of the system decreases.
Chen, Jui-Shui, and 陳瑞穗. "Porous polylactide scaffolds prepared by thermally induced phase separation." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/62874430026093483385.
Повний текст джерела國立陽明大學
醫學工程研究所
90
Porous polylactide scaffolds have been extensively explored for drug delivery carriers and tissue engineering due to their biocompatibility. The porous scaffolds support for cell attachment、proliferation、migration、supply of nutrients should meet several requirements: highly porous and surface area、interconnected pore structure and good mechanic properties. In this research, we fabricated porous polylactide scaffolds with highly porous and interconnected structures by TIPS technique. The various porous structures can be easily obtained by adjusting thermodynamic and kinetic parameters. We investigated the main experimental parameters as molecular weight, concentration, temperature, and time that relate to morphology of PLA scaffolds. In addition, hydrophobic PLA scaffolds apply to cell transplantation can be efficiently wet by ethanol. We studied the dimension stability and microstructure of DLPLA scaffolds that prewetted by ethanol. The results show that inclusion of nonsolvent cause the polymer solution separated into two phases at high temperature easily. Liquid-liquid phase separation at 72℃ in 30wt%DLPLA with 85/15 dioxane/water mixture. On the other hand, Liquid-liquid phase separation wasn’t occurred in the polymer solution without DLPLA (100/0 dioxane/water mixture). The morphology of scaffolds shows a regular morphology at high molecular weight. Furthermore, pore size was increased with high phase separation temperature, long coarsening time, and high concentration of nonsolvent. The lacy-structure,interconnective and high porosity scaffolds were fabricated in spinodal decomposition mechanism. The DLPLA scaffolds structure was shrinkage after prewetted by pure ethanol, it leads to decrease the intrusion volume of buffer. Besides, dimension and microstructure of DLPLA scaffolds were not being shrunk by 50/50 ethanol/water in 30min. The treatment was suggested to ensure well water infiltration and microstructure stability properties.