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Dissertations / Theses on the topic 'Melt crystallization'
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Kim, Kwang-Joo. "Impurity distributions in crystalline solid layer in melt crystallization /." Aachen : Shaker, 2002. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009698552&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Tähti, Tero. "Suspension melt crystallization in tubular and scraped surface heat exchangers." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=973404914.
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Beierling, Thorsten [Verfasser]. "Separation of isomeric compounds using layer melt crystallization / Thorsten Beierling." München : Verlag Dr. Hut, 2014. http://d-nb.info/1052375669/34.
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Tavichai, Orasa. "Effect of shear on growth rates during polyethylene melt crystallization." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33996.
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During processing, polymers are exposed to complex thermal and deformation fields. Under these conditions, partially crystalline polymers undergo crystallization, which contributes significantly to their ultimate properties. While the thermal effects on polymer crystallization have been studied extensively, there is much less research carried out with regard to the effects of deformation and stress on crystallization kinetics. This is in part due to experimental difficulties in making appropriate measurements. In the present work, the Linkam Shearing Cell, in conjunction with a polarized light microscope, was used to study the effect of shear on the growth kinetics of various linear low-density polyethylene (LLDPE) resins. Simultaneously, an effort was made to evaluate the effect of shear on morphology. The experimental and analytical aspects of the work will be described, and preliminary results will be reported.The spherulitic growth rate increased under shear compared to that under quiescent conditions. The circular shape morphology of spherulites was obtained under the shear rate range of consideration (0--1 s-1). The effect of molecular structure in terms of co-monomer and branching content on spherulitic growth rate under quiescent and shear condition was observed. Moreover, the effect of temperature on growth rate under quiescent and shear (0.5 s-1) was studied. The modified Lauritzen-Hoffman equation was used to fit experimental data. The diffusion energy barrier under shear condition (0.5 s-1) was estimated and was found to be lower than the diffusion energy barrier under quiescent conditions.
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Seidel, Felix Johannes [Verfasser]. "Additives for faster separation in melt layer crystallization / Felix Johannes Seidel." Halle, 2017. http://d-nb.info/1137509872/34.
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Hengstermann, Axel [Verfasser]. "A new approach to industrial melt crystallization of acrylic acid / Axel Hengstermann." Aachen : Shaker, 2010. http://d-nb.info/1081887257/34.
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Agarwal, Uday S. "Orientation and crystallization in melt-spinning of poly(ethylene terephthalate) based compositions." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/9975.
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Tähti, Tero [Verfasser]. "Suspension Melt Crystallization in Tubular and Scraped Surface Heat Exchangers / Tero Tähti." Aachen : Shaker, 2004. http://d-nb.info/1172613206/34.
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Lüdecke, Uta [Verfasser]. "Fractionation of multi-component fatty acid mixtures by melt crystallization / Uta Lüdecke." Aachen : Shaker, 2004. http://d-nb.info/1170537456/34.
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Descher, Stefan [Verfasser]. "Modeling and simulation of crystallization processes in polymer melt flows / Stefan Descher." Kassel : kassel university press c/o Universität Kassel - Universitätsbibliothek, 2021. http://d-nb.info/1231385715/34.
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Tang, Haihao [Verfasser], Joachim [Akademischer Betreuer] Ulrich, and Marjatta [Akademischer Betreuer] Louhi-Kultanen. "Purification of phosphoric acid by melt crystallization / Haihao Tang ; Joachim Ulrich, Marjatta Louhi-Kultanen." Halle, 2016. http://d-nb.info/1116951452/34.
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Esposito, Rosario. "Studies of volatile evolution in magmatic systems using melt inclusions." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28287.
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Understanding volatile evolution associated with active volcanic magmatic systems is of paramount importance because volatiles control and determine the magnitude of an eruption owing to the large change in molar volume that volatile species show depending on their physical state (volatiles dissolved in silicate melts vs. volatiles exsolved as vapor). For active volcanic systems studying the volatile evolution can help to assess the potential hazard associated to a certain locality. Also, volatile evolution in magmatic system controls the formation of certain ore deposits.
Despite the importance of understanding volatile evolution of magmatic systems, concentrations of volatiles of evolving magmas are not easily available especially for magmas originated in the deep crust. Fortunately, sample of melts can be entrapped as melt inclusion (MI) into growing igneous minerals in crystalizing magma chamber. After the entrapment, the crystal works as an insulating capsule from the external magmatic environment.
Researchers have started to use MI because they provide some advantages in respect to the classical whole rock approach to petrological studies. One of the most important advantages is that MI often represent sample of a deep and non-degassed melt (glass) available at Earth's surface. In fact, with the exception of deep ocean basalts, igneous whole rocks found at the Earth's surface are degassed magmas.
This dissertation is a compilation of four publications produced during six years of research and is addressed to give a contribution in understanding the volatile evolution in magmatic systems and also to improve the present understanding of information that can be obtained using the melt inclusions technique.
In the first chapter, I present an alternative interpretation of H₂O-CO₂ trends obtained from MI. In this study, we demonstrate that these trends can be due to post entrapment crystallization on the wall of the MI and not to magma ascent. This alternative view is more realistic especially for cases where in the same phenocrysts MI show strongly different CO₂ concentrations.
In the second chapter, I present a study to test for the MI reliability in recording volatile concentrations. We used the approach of the melt inclusion assemblage (MIA) that consists of analyzing groups of MI presumably entrapped at the same time and, thus, at same chemical and physical conditions. The results show that most of the MIA studied show consistent volatile concentrations corroborating the reliability of the MI technique. CO₂ shows the highest degrees of variability and we have assessed this behavior mostly to C-contamination in the surface of the sample.
The third chapter is a study case (the Solchiaro eruption in Southern Italy) that shows the potential uses of MI to understanding the volatile evolution. I present a model showing the dynamic of the magma based on MI. This study also discusses the origin of anomalous MI and which MI provide the best information.
The final chapter is dedicated to test the applicability of the new Linkam TS1400XY heating stage. I was able to show how this new microthermometric tool is capable of homogenizing MI at high temperature and to quench MI to a homogeneous glass state.Ph. D.
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Abouzeid, Ahmed [Verfasser]. "Application of a new technology utilizing melt crystallization for the production of coated tablets / Ahmed Abouzeid." Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, Halle, Hochschulschriften, 2015. http://d-nb.info/1167933214/34.
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AHMAD, MUHAMMAD [Verfasser], Joachim [Akademischer Betreuer] Ulrich, and Heike [Akademischer Betreuer] Lorenz. "Separation of complex feed streams of products by layer melt crystallization / Muhammad Ahmad ; Joachim Ulrich, Heike Lorenz." Halle, 2016. http://d-nb.info/1116952335/34.
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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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Dasgupta, Sunanda [Verfasser], Peter [Gutachter] Ay, and Christian [Gutachter] Stollberg. "Metastable zone determination and nucleation kinetics during melt crystallization of poly-unsaturated fatty acids / Sunanda Dasgupta ; Gutachter: Peter Ay, Christian Stollberg." Cottbus : BTU Cottbus - Senftenberg, 2018. http://d-nb.info/1151520810/34.
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De, Neef Alexandre. "Processing of PVDF/PMMA Films by Melt-State Extrusion-Casting : Impact of PMMA on Beta-Phase Crystallization and Related Piezo/Ferroelectric Properties." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2019. http://www.theses.fr/2019MTLD0018.
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Ces travaux de doctorat visent à étudier la mise en forme de matériaux polymères piézoélectriques via des procédés de plasturgie pour des applications émergentes (capteurs et µ- générateur d’énergie, notamment pour le domaine des objets connectés autonomes en énergie). Les travaux ont été ciblés sur le poly(fluorure de vinylidène) (PVDF) en raison de ses performances piézoélectriques élevées. La structure/phase cristalline polaire β du PVDF est nécessaire mais peut s’obtenir par étirage ou copolymérisation. Ces travaux proposent une approche alternative de type « mélange de polymères » par extrusion en voie fondue pour modifier la cristallinité du PVDF via l’addition du poly(méthacrylate de méthyle) (PMMA), possédant un caractère miscible et un impact sur la cristallisation en phase β du PVDFThis PhD work aims to study the casting of piezoelectric polymer materials via plastics processes for emerging applications (sensors and µ-energy generator, especially for the domain of autonomous connected objects in energy). Work has been focused on polyvinylidene fluoride (PVDF) because of its high piezoelectric performance. The crystalline polar β structure/phase of PVDF is necessary but can be obtained by stretching or copolymerization. This work proposes an alternative approach of the "polymer blend" type by melt-state extrusion to modify the crystallinity of PVDF via the addition of poly (methyl methacrylate) (PMMA), having a miscible character and an favorable impact on crystallization in β-phase of PVDF
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Tuohy, Robin. "Olivine Crystallization Depths within Kilauea's Lower East Rift Zone: The Use of Rehomogenized Melt Inclusions to Interpret Magma Transport, Storage, and Energetic Fountaining." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/17900.
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H2O and CO2 concentrations in olivine-hosted melt inclusions, assuming vapor saturation at the time of trapping, can be used to estimate crystallization depths for the olivine host. Estimating the true CO2 in melt inclusions is difficult, as much is lost to shrinkage bubbles, which form upon post-entrapment cooling and crystallization. Reheating olivine to temperatures above the melt inclusion trapping temperature and then quenching rapidly can restore CO2 to the glass because the CO2 in the bubble redissolves at high temperature. Previous work has established that olivine crystallization for the1959 Kilauea Iki eruption took place in the shallow summit reservoir, but crystallization depths have not been established for the rift extension of the eruption, at Kapoho. The new data presented here suggest that the most primitive Kilauea Iki component bypassed the summit reservoir for the east rift zone prior to the start of the eruption and was later erupted at Kapoho.
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Lanyi, Franz J. [Verfasser], Dirk W. [Akademischer Betreuer] Schubert, Dirk W. [Gutachter] Schubert, and Rainer [Gutachter] Adelung. "Modification of Interfacial Properties of Polypropylene Fibers using Hydrophilic Melt Additives - Interactions with Crystallization / Franz J. Lanyi ; Gutachter: Dirk W. Schubert, Rainer Adelung ; Betreuer: Dirk W. Schubert." Erlangen : FAU University Press, 2020. http://d-nb.info/1220911240/34.
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Shan, Haifeng. "Structure development in melt spinning, cold drawing and cold compression of poly(ethylene-co-octene) with different octene content." Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1137341440.
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Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2006."May, 2006." Title from electronic dissertation title page (viewed 10/11/2006) Advisor, James L. White; Committee members, Avraam I. Isayev, Thein Kyu, Darrell H. Reneker, Shing-Chung "Josh" Wong; Department Chair, Sadhan C. Jana; Dean of the College, Frank N. Kelley; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Shah, Zulfiqar Hussain. "Synthesis and Characterizations of Fe-based Metallic Glassy Systems." Thesis, KTH, Materialvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37395.
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This thesis is a study of tailoring amorphous Fe-B-Si based alloy to produce bulk glassy rods by adding Nb. We have prepared rapid quenched thin ribbons (thickness ~12 µm) by melt spinning, and glassy rods of diameter ~1mm by Cu-mold casting based on compositions (Fe0.78B0.13Si0.9)100-xNbx (x=0, 4, 8, 12), and studied their different physical properties. The melt-spun ribbons are found to be X-ray amorphous, whereas some nano-crystallinity is observed in the case of rods. All the ribbons show high saturation magnetization and low coercivity, which are the desirable characteristics of a soft ferromagnet. These ribbons are thus suitable for designing high frequency transformers, and sensors from an applications point of view. With increasing Nb content their saturation magnetization, ferromagnetic Curie temperature, and resistivity are found to decrease as expected. The temperature dependence of electrical resistivity shows small positive temperature co-efficient that is expected for a metallic disordered material. We have also studied the modification of the properties on thermal annealing the (Fe0.78B0.13Si0.9)96 Nb4 ribbon at different temperatures in a neutral atmosphere.
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Bai, Xianming. "Thermodynamics and Kinetics of Phase Transitions during Supercooling and Superheating: A Theoretical and Computational Investigation in Model Lennard-Jones Systems." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11132006-110828/.
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Thesis (Ph. D.)--Materials Science and Engineering, Georgia Institute of Technology, 2007.Martha A. Gallivan, Committee Member ; Andrei G. Fedorov, Committee Member ; Christopher Summers, Committee Member ; Thomas H. Sanders, Jr., Committee Member ; Mo Li, Committee Chair.
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Peixoto, Erilaine Barreto. "Estudo dos processos de cristalização em fitas magnéticas amorfas." Universidade Federal de Sergipe, 2015. https://ri.ufs.br/handle/riufs/5355.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESIn this work, we study the crystallization process in the Fe40Ni40P14B6 and Fe76.5Cu1Nb3Si13.5B6 amorphous magnetic ribbons fabricated by melt spinning technique. The effect of crystallization on the magnetic properties is studied via MvsH data at room temperature carried out to as-cast and heated samples. X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), magnetization of the magnetic field (MvsH) and magnetization versus temperature (MvsT) are reported. The values of Curie temperatures determined via TGA measurements are in agreement with that estimated via MvsT data. DSC measurements are carried out in isothermal and non-isothermal modes, and from the non-isothermal results, we define the temperatures of the isotherms. These isothermal data were fitted using the Johnson-Mehl-Avrami (JMA) model to Fe40Ni40P14B6 ribbon yielding an Avrami exponent, m > 2.5, to isothermal curves in the onset of crystallization process and 1.5 < m < 2.5 to intermediate regions of crystallization process. It is worth to comment that we are able to fit the non-isothermal curves for using the JMA model. XRD measurements taken after TGA measurement (T = 800oC) allow us to identify nanoparticles with Fe-Ni-based and Fe3B0.82P0.18 crystallographic phases to Fe40Ni40P14B6 ribbon and nanoparticles with Fe3Si crystallographic phase to the case of Fe76.5Cu1Nb3Si13.5B6 ribbon. The MvsH data are consistent with the crystallization processes which take place in amorphous magnetic materials.
Neste trabalho, nós estudamos os processos de cristalização em fitas magnéticas amorfas de Fe40Ni40P14B6 e Fe76.5Cu1Nb3Si13.5B6 fabricadas através da técnica de melt spinning. As medidas das curvas de MvsH a temperatura ambiente nas fitas como produzidas e tratadas termicamente permitiram estudar o efeito da cristalização nas propriedades magnéticas. As amostras foram caracterizadas através de medidas de difração de raios X (DRX), calorimetria exploratória diferencial (DSC), termogravimetria (TGA), magnetização em função do campo magnético (MvsH) e magnetização em função da temperatura (MvsT). Medidas de TGA mostraram-se eficazes para determinação da temperatura de Curie desses materiais, confirmadas pelas medidas de MvsT. Nós também realizamos medidas de DSC nos modos isotérmicos e não isotérmicos e, a partir dos resultados não isotérmicos, nós definimos as temperaturas de realização das isotermas. Em seguida, o modelo de Johnson-Mehl-Avrami (JMA) foi aplicado para a fita de Fe40Ni40P14B6. Para esses dados, o modelo JMA foi satisfeito e o valor do expoente de Avrami foi de m > 2.5 na região onde a curva de fluxo de calor aumenta e 1.5 < m < 2.5 nas regiões intermediárias entre o início do aumento da curva e pico de cristalização. Para as curvas não isotérmicas, o modelo de JMA não foi satisfeito. Para a fita de composição Fe76.5Cu1Nb3Si13.5B6 o modelo de JMA não foi testado. As medidas de DRX realizadas na fita de Fe40Ni40P14B6 após tratamento térmico identificaram fases nanocristalinas a base de Fe-Ni e contendo Fe3B0.82P0.18 e para a fita de Fe76.5Cu1Nb3Si13.5B6 a fase Fe3Si foi observada. As medidas de MvsH confirmaram as mudanças nas propriedades magnéticas de acordo com as frações cristalizadas dos materiais.
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Le, Page Mostefa Marie. "Développement, conception et mise au point d'un procédé de purification du bio-acide acrylique par cristallisation en milieu fondu." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0302/document.
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Actuellement produit à partir du pétrole, une voie de synthèse de l'acide acrylique (AA) à partir du glycérol est envisagée. Cependant, cet AA bio-sourcé contient davantage d'acide propionique (AP) que l'AA issu du propylène. Les techniques classiques de purification ne permettent pas de séparer les deux acides. Le diagramme de phases liquide-solide du binaire AA + AP est déterminé. Il présente un point eutectique à 25,65 % (mol) d'AA, un point péritectique à 50,00 % (mol) d'AA et donc, un large domaine dans lequel l'AA cristallise thermodynamiquement de façon pure. Les essais de purification en mode statique sur paroi froide affichent des résultats prometteurs, une efficacité de séparation correcte pour un rendement de 60 %. Afin d'améliorer les transferts de matière et de chaleur, des dispositifs en mode dynamique sont mis au point dont un cristallisoir en film tombant. Ce dispositif permet de multiplier par 2,8 la productivité, tout en conservant une bonne efficacité de séparation. Afin de diminuer la surfusion et de maintenir un bon transfert thermique malgré une couche cristalline relativement isolante, des surfaces de cristallisation micro- et milli-structurées sont envisagées. La productivité est encore améliorée et la modélisation du transfert thermique confirme ces résultats expérimentaux. Afin de se rapprocher des conditions industrielles, un brut synthétique de bio-AA est purifié. La cristallisation en milieu fondu permet de séparer toutes les impuretés testées. Enfin, un modèle de cascade de cristallisoirs fermés, avec recyclage des différentes phases, est proposé afin de dimensionner le procédé global. Les essais en conditions presque réelles et l'intensification du procédé de cristallisation permettent d'envisager sereinement la mise en oeuvre du procédé industrielWith a global market exceeding four million tons per year, acrylic acid (AA) is a major intermediate chemical. The current AA synthesis is based on propylene, which is produced from oil. Thus, a novel production route is envisioned, based on glycerol, a green byproduct of oleochemistry and biodiesel production. However, current crude biobased AA contains a higher proportion of PA than AA from petrochemical origin. Classical purification techniques of AA cannot efficiently separate these two chemicals. In a first part, liquid-solid phase diagram of the binary system AA + PA is determined. This liquid-solid equilibrium exhibits an peritectic behavior at 50.0% (mol) of AA, a eutectic point at 25.65% (mol) of AA and thus, this diagram is favorable to the purification of AA. First purification tests by static solid layer melt crystallization show promising results: a correct separation efficiency for a yield varying between 60 et 70 %. To improve heat and mass transfer, dynamic crystallization set-up are developed, including a falling film crystallizer. This set-up multiplies by 2.8 the productivity of purification, while keeping a good separation efficiency. To reduce supercooling and to keep a good heat transfer despite the crystalline layer which is a thermal insulator, micro-and milli-structured crystallization surface are considered. Productivity is further improved and heat transfer modeling confirms the experimental results. To be nearer to industrial conditions, synthetic crude bio-AA is purified. Melt crystallization can separate all the impurities which are present in the medium. To scale-up the overall process a cascade model of batch crystallizers with recycling of the differents phases, is proposed. The intensification of the melt crystallization process permits to consider the implementation of the industrial process
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Lee, Oi Wun. "Experimental study of post-shear crystallization of polypropylene melts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/MQ44020.pdf.
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Htira, Thouaiba. "Traitement d’eaux usées industrielles par congélation sur paroi froide." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1155/document.
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Ce travail vise à étudier un procédé de traitement d'eaux usées industrielles par cristallisation en milieu fondu sur paroi froide. Deux effluents modèles sont choisis : un mélange eau/acétone et un mélange eau/acide propanoïque. Dans un premier temps, l'équilibre solide-liquide du mélange est étudié pour connaitre les limites de l'étude en température et en concentration. Le procédé de traitement de l'eau est alors conduit, selon un mode opératoire précis. Deux modes de fonctionnement sont mis en œuvre, un mode statique et un mode dynamique avec une circulation en boucle de la solution. La concentration en impuretés dans la glace est analysée après chaque cycle de congélation. L'étude paramétrique, conduite suivant un plan d'expériences, a mis en avant les effets importants de la concentration initiale de la solution et de la rampe de refroidissement. La microstructure de la glace est également analysée par microscopie en chambre froide pour interpréter les mécanismes d'incorporation d'impuretés au sein de la glace. Les inclusions de liquide sont sous la forme de poches de solution à faible vitesse de croissance et sont localisées dans les joints de grain à plus forte vitesse. Enfin, la modélisation du procédé fonctionnant en mode statique, par les éléments finis et en 2D axisymétrique avec frontière mobile, montre la présence de mouvements de convection. En mode dynamique, l'hydrodynamique de l'écoulement dans l'espace annulaire est décrite par une modélisation 3D prenant en compte la position de l'entrée et de la sortie. Les résultats démontrent la faisabilité du procédé et permettent des avancées significatives dans la compréhension des phénomènes mis en jeuThis work aims to study a process of industrial wastewater treatment by melt crystallization on a cold wall. Two effluent model solutions are chosen: water/acetone and water/propionic acid binary mixtures. First, the solid liquid phase diagrams are determined experimentally in order to delimit the operating range of temperature and concentration. Then, a parametric study of the wastewater treatment process by freezing is performed, by means of an experimental design, for two working modes, static mode and dynamic mode by adding a recirculation loop, respectively. The impurity concentration in the ice is analyzed after each freezing cycle. The process requires applying very precise conditions and the ice concentration mainly depends on the initial solution concentration and on the applied cooling rate. The ice microstructure is also characterized by optical microscopy in a cold chamber and gives insights into the mechanism of impurity incorporation: the liquid inclusions are localized under the form of solution pockets at low growth rate or between the polycrystals at higher growth rate. Lastly, 2D axisymmetric modelling of the process in static mode, based on finite elements and taking into account the moving boundary, shows the presence of buoyancy loops in relation with the density dependence of the solution with temperature. In dynamic mode, the hydrodynamics in the annular space is described by a 3D model to account for the positions of the inlet and outlet pipes. All the results demonstrate the process feasibility and allow better understanding of the occurring phenomena
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Boukaré, Charles-Edouard. "Dynamique du manteau dans la jeune Terre." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1011/document.
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Dans les premiers instants de l'histoire des planètes telluriques, la chaleur d'accrétion, le chauffage radioactif et la différenciation noyau-manteau apparaissent comme des sources d'énergie capables de fondre le manteau terrestre significativement. L'évolution d'un océan de magma suite à ces évènements catastrophiques dépend des propriétés physiques des matériaux silicatés en conditions mantelliques et de la dynamique convective complexe d'un manteau en cristallisation. Actuellement, certains auteurs proposent que la structure actuelle du manteau profond pourrait être associée à des reliques de la cristallisation d'un océan de magma primitif. Nous avons développé un modèle thermodynamique capable de modéliser de façon auto cohérente des séquences de cristallisation dans les conditions du manteau profond. A partir de ce modèle, nous avons montré que le magma s'enrichit progressivement en fer au cours de la cristallisation. Le liquide résiduel devient ainsi plus dense que la phase solide. Ce modèle thermodynamique suggère un scénario de cristallisation de l'océan de magma similaire à celui proposé par (Labrosse et al., 2007). Celui-ci prédit que la structure actuelle de la base du manteau hériterait de la cristallisation d'un océan de magma primitif. Afin d'étudier l'influence de ce contraste de densité et des profils de liquidus sur la dynamique syn- cristallisation d'un océan de magma, nous avons développé un code de convection multiphasique intégrant changement phase, percolation / compaction et cristallisation fractionnée. Dans ce mémoire, nous présentons des modèles dynamiques préliminaires de cristallisation dans le cas univariantEarly in the history of terrestrial planet, heat of accreation, radioactive deacay and core-mantle segratation may have melted the silicate mantle significantly. Magma ocean evolution depends on both physical properties of materials at relevant P-T conditions and the complex dynamics of a convecting cristallizing mantle. Present deep Earth mantle structures might be direclty linked to the crystallization of a potential magma ocean. We propose a complete thermodynamic model of the solid-liquid equilibrium in the MgO-FeO-SiO2 system which allows to compute self-consistenltly crystallization sequence at deep mantle conditions. The present study shows that, at thermodynamic equilibrium, the first solids that crystallize in the deep mantle are lighter than the liquid as they are more Mg-rich. This further enriches the melt in iron and this residual melt becomes much denser than the solid phase. Both the anti-freeze effect of iron and its high density suggest a mantle crystallization scenario similar to that described in Labrosse et al. (2007) where the ULVZ are iron rich and very fusible remnants of a primordial basal magma ocean. In addition, we have developped a multiphase convection code accounting for solid-liquid phase change, compaction and fractionnal cristallization. This mechanical model is dedicated to the investigation of the effects of various temperature profile and solid liquid density cross-overs on the dynamics of a cristallizing mantle. In this thesis, we show preliminary models illustrating the effect of chemical density contrasts between melt and solid in the case of univariant crystallization
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Schwartz, Frédéric. "Etude des parametres d'elaboration de rubans amorphes par la methode du flot planaire : influence d'elements de substitution sur les proprietes d'un alliage amorphe fe::(79)b::(16)si::(5)." Paris 6, 1986. http://www.theses.fr/1986PA066574.
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Description de la methode de filage depuis l'etat liquide. Influence des parametres de fabrication sur la qualite micrographique des rubans amorphes de composition donnee. Application de cette methode a l'amorphisation de l'alliage ferromagnetique fe::(79)b::(16)si::(5). Effet de la substitution de differents elements sur les temperatures de cristallisation et de curie de l'alliage ferromagnetique
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Karathanou, Argyro. "Image processing for on-line analysis of electron microscope images : automatic Recognition of Reconstituted Membranes." Phd thesis, Université de Haute Alsace - Mulhouse, 2009. http://tel.archives-ouvertes.fr/tel-00559800.
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The image analysis techniques presented in the présent thesis have been developed as part of a European projeet dedicated to the development of an automatic membrane protein crystallization pipeline. A large number of samples is simultaneously produced and assessed by transmission electron microscope (TEM) screening. Automating this fast step implicates an on-fine analysis of acquired images to assure the microscope control by selecting the regions to be observed at high magnification and identify the components for specimen characterization.The observation of the sample at medium magnification provides the information that is essential to characterize the success of the 2D crystallization. The resulting objects, and especially the artificial membranes, are identifiable at this scale. These latter present only a few characteristic signatures, appearing in an extremely noisy context with gray-level fluctuations. Moreover they are practically transparent to electrons yielding low contrast. This thesis presents an ensemble of image processing techniques to analyze medium magnification images (5-15 nm/pixel). The original contribution of this work lies in: i) a statistical evaluation of contours by measuring the correlation between gray-levels of neighbouring pixels to the contour and a gradient signal for over-segmentation reduction, ii) the recognition of foreground entities of the image and iii) an initial study for their classification. This chain has been already tested on-line on a prototype and is currently evaluated.
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Slaughter, Douglas Wesley. "Fundamental studies in melt crystallization." 1996. https://scholarworks.umass.edu/dissertations/AAI9709655.
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While solid-liquid separations have been in use for many years, new constraints (environmental as well as economic) and the advent of specialty chemicals have led to a greater interest in these separation systems as process alternatives. Useful to the evaluation of these systems as design alternatives is an equation-based design procedure. Developing such a design procedure for melt crystallization systems requires the equilibrium behavior of the system to be investigated and understood before the complications of crystal growth kinetics are included. This hierarchical approach to the development of the design procedure allows for simpler models (i.e., the equilibrium calculations) to be evaluated and used to reduce the number of design choices. A model is developed for calculating solid-liquid phase equilibria of compound-forming systems. The method treats the compound as a new component containing stoichiometric amounts of the constituent species. The overall method is quite easy to implement and successfully reproduces the phase diagrams for a variety of complex mixtures, including organic melt systems and compound semiconductor systems. This technique is used as the basis for calculating crystallization path maps for ternary equilibrium crystallizers in which both compounds and eutectics occur. Crystallization path maps are similar to residue curve maps in VLE systems, and help to determine overall system behavior especially with regard to feasibility and design of melt crystallization processes. This phase equilibrium model is incorporated into a model of the kinetics of crystal growth in a suspension melt crystallizer. The kinetic model tracks the crystal size (for a monodisperse distribution of crystals), linear growth rate, the rate of solid formation, composition in both the liquid and solid phases, and the temperature of the bulk liquid for a given cooling policy for the crystallizer. A sensitivity analysis of the kinetic model is performed. Also, the phase equilibrium and kinetic models are applied to two example systems and the implications for design are discussed.
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莊萬昇. "Suspension crystallization of para-dichlorobenzene from melt." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/23758472762526986142.
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Grall, Daniel S. "Kinetics of butterfat crystallization from the melt." 1991. http://catalog.hathitrust.org/api/volumes/oclc/25100545.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1991.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 114-119).
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Shih, Kai-Wun, and 石凱文. "Investigation of Polymer Melt-Crystallization Mechanism and Morphology." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/13061848146388478592.
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碩士國立東華大學
材料科學與工程學系
99
The melt crystallization process of two classical crystallized polymer (polyethylene and syndiotactic polystyrene) is to be examined by means of TEM and AFM for this study. There are considerable amount of nanograins formed at the beginning, and they can be mainly divided into two categories, which are the disc-like ones and the tower-like ones. The polymer chains of the disc-like ones would be perpendicular or parallel to the sample surface, with height of less than 20 nm. However, these nanograins might coalesce at the initial phase of crystallization because of a high density of nucleation, resulting in the polymer chains’ random arrangement of worm-like nanograins. The entire polymer chains of the tower-like nanograins are parallel to the sample surface yet developed perpendicularly. There are three primary polymer crystallization mechanisms having been proposed in the literature: 1. A hexagonal mesophase developed from the outset of the crystalline phase proposed by Stephen Z. D. Cheng and Lotz. 2. That a mesomorphic layer being absorbed at first, then thickening and turning into a constant arranged granular crystal layer, finally into homogeneous lamellar crystallines proposed by Strobl. 3. That the lamellar were coalesced by nanograins proposed by Jeng U. et al. However, based on our experiments, nanograins would be melting into a state of fusion and connecting each other at the early stage of melt crystallization instead of growing and coalescing into lamellae. We found that here were great amount of nanograins formation at the initial stage, the nanograins then coalesced and melted into the fusion mesophase which was amorphous. In the last stage the fusion droplets were solidified and transformed into a large scale of lamella. Thus, a newly discovered crystallization mechanism will thus be proposed, developed and illustrated further in this study.
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Ghosal, Anindya Kumar. "Crystallization of isotactic poly(propylenes) with enhanced melt strength." 2008. http://etd.lib.fsu.edu/theses/available/etd-02142008-134818/.
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Thesis (Ph. D.)--Florida State University, 2008.Advisor: Rufina G. Alamo, Florida State University, FAMU-FSU College of Engineering, Dept. of Chemical Engineering. Title and description from dissertation home page (viewed July 8, 2008). Document formatted into pages; contains xix, 250 pages. Includes bibliographical references.
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Hu, Qiongying. "Dynamics of Melt-mediated Crystallization of Amorphous Silicon Films." Thesis, 2011. https://doi.org/10.7916/D85X2H0V.
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This thesis reports on the new experimental findings and the corresponding conclusions that were made regarding the pulsed-laser-induced melting-and-solidification behavior of a-Si films. In particular, it focuses on investigating the melt-mediated crystallization details that are associated with the a-Si films, which presumably do not contain preexisting microcrystal clusters (as for instance can be formed via high-dose ion-irradiation of Si wafers and PECVD deposition of a-Si films). Whereas the behavior of microcrystalline-cluster-containing a-Si films within the partial-melting regime was well characterized and accounted for [1], a more intrinsic, and, therefore, more fundamentally important situation involving microcrystalline-cluster-deficient a-Si films in the partial melting regime has yet to be definitively resolved. The present thesis addresses this unsatisfactory situation. The samples used in this work consisted of 50nm to 200nm dehydrogenated PECVD a-Si films (with or without additional ion irradiation of the films) on SiO2-coated glass and quartz substrate. Single-shot irradiation experiments using an excimer-laser-based system were conducted at various pulse durations (30ns-Gaussian-profile beam to 250ns beam obtained via an optical pulse duration extender) and at various energy densities. Extensive in situ transformation analysis was performed using both front-side and back-side transient reflectance measurements also microstructural characterization of the irradiated films was conducted using TEM and AFM. The experimental findings obtained in this investigation reveal that these a-Si films can melt and solidify in ways that are quite distinct, more varied, and highly complex compared to those encountered in microcrystalline-cluster-rich a-Si films. Specifically: (1) spatially dispersed and temporally stochastic nucleation of crystalline solids occurring relatively effectively at the moving liquid-amorphous interface, (2) very defective crystal growth that leads to the formation of fine-grained Si proceeding, at least initially after the nucleation, at a sufficiently rapidly moving crystal solidification front, and (3) the propensity for local preferential re-melting of the defective regions and grain boundaries (while the beam is still on) are some of the fundamental factors that can participate and affect how these films melt and solidify. We discuss, by providing an extensive and critical review of the relevant papers, how the present conclusions are fundamentally distinct from those that have been made by the previous investigators in the field. The implications of these findings on the conventional ELA (i.e., excimer-laser annealing) method as well as the possibility of developing partial-melting-regime-based ultra-high-throughput crystallization methods are also discussed.
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Ke, Yi Chih, and 柯奕志. "The growth kinetics of para-xylene in melt crystallization." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/v9n3x8.
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碩士長庚大學
化工與材料工程學系
104
The growth kinetics of para-xylene (PX) crystal layer growing perpendicular to a cooled wall have been studied in the stirred PX/ortho-xylene (OX) mixture melt and PX/meta-xylene (MX) mixture melt for the initial PX concentrations of 0.7-0.9. Firstly, the obtained growth rate data are fitted to the overall empirical growth model. For the PX-OX system, the growth activation energy is 24.9kJ/mol with the growth order of 1. For the PX-MX system, the growth activation energy of 25.1kJ/mol with the growth order of 1. Both systems suggest that the growth of PX is diffusion controlled. Consequently, the same growth rate data are fitted well to a diffusion controlled growth form, in which the mass transfer coefficient is assumed proportional to temperature and inversely proportional to the solution viscosity. The effective distribution coefficient is then calculated for each initial PX concentration. The results indicate that melt crystallization can be efficiently employed for purification of PX from the mixture.
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Xu, Cheng Zhe, and 許承哲. "The growth kinetics of acrylic acid in melt crystallization." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/f255a3.
Full textAbstract:
碩士長庚大學
化工與材料工程學系
104
The growth kinetics of acrylic acid crystal layer growing perpendicular to a cooled wall have been studied in the stirred acrylic acid and propionic acid mixture melt for the initial acrylic acid concentrations of 0.75-0.95. The obtained growth rate data are fitted to the overall empirical growth model. It is found that the growth activation energy is with the growth order of 1.4. This suggests that the growth of acrylic acid is surface reaction controlled. The effective distribution coefficient is calculated for each initial acrylic acid concentration. The results indicate that melt crystallization can be employed for purification of acrylic acid from the mixture.
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Bakeev, Katherine Antolin. "Melt crystallization of ferroelectric copolymers of poly(vinylidene-fluoride-trifluoroethylene)." 1993. https://scholarworks.umass.edu/dissertations/AAI9408254.
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This dissertation is a study of the phase transition and melt crystallization of ferroelectric copolymers of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) containing 83 mol% poly(vinylidene fluoride). The microstructure of crystallized P(VDF-TrFE) are characterized by vibrational spectroscopy to determine their chain conformation distribution, wide-angle X-ray diffraction (WAXD) to measure the crystal structure and determine the content of $\alpha$ and $\beta$ crystal phases. Differential scanning calorimetry (DSC) is used to measure the transition temperatures and their enthalpies. P(VDF-TrFE) is a polymorphic system exhibiting a Curie transition below its melting temperature, at which the copolymer undergoes a long range conformational change from a predominantly trans structure ($\beta$ phase) which can be ferroelectric, to a structure which has a mixture of trans and gauche conformations and is called the paraelectric $\alpha$ phase. Variable temperature FTIR studies have been made to follow the phase transition and to understand the multiple phase behavior that has been suggested for these copolymers. Factor analysis has been applied to the FTIR data to determine the number of crystal phases present for this copolymer composition. Melt crystallization under nonisothermal and isothermal conditions has been used to modify the structure of the copolymers and change both the Curie and melting temperatures. It is found that with slow cooling rates from the melt through the crystallization temperature, there is a stabilization of the paraelectric $\alpha$ phase which is then retained to different degrees on passing through the Curie transition on cooling. Under all crystallization conditions the copolymers exhibit two Curie transitions on cooling whose temperatures and intensities vary with cooling rate and crystallization time. The Curie temperature on cooling and subsequent heating is decreased upon slower cooling, reflecting an increase in the gauche chain conformers as evidenced by FT-Raman spectroscopy. WAXD data show that there are $\alpha$ and $\beta$ phase crystals present in samples that have been cooled slowly, accompanied by an increase in interplanar spacing which indicates that the $\beta$ phase also contains gauche defects. Longer isothermal crystallization at 135$\sp\circ$C shows also that there is an increase in $\alpha$ phase content with longer crystallization time, though when crystallization is carried out at 135$\sp\circ$C there is always a coexistence of $\alpha$ and $\beta$ phases in the final room temperature structure. Highly oriented P(VDF-TrFE) copolymers were prepared by solid-state coextrusion to aid in understanding the vibrational assignments in the copolymer. Infrared dichroism and WAXD were used to assess the sample orientation and measure the transition moment angles for some of the vibrations in the spectrum.
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Liu, Kun Yen, and 劉昆諺. "Effects of impurities on the growth kinetics in melt crystallization." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/874jfb.
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Chiang, Meng Han, and 江孟翰. "Separation of p-xylene and m-xylene mixtures by melt crystallization." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/72004528264856218093.
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Bischoff, White Erica E. "Extensional-flow-induced Crystallization of Polypropylene." 2011. https://scholarworks.umass.edu/theses/665.
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A filament stretching extensional rheometer was used to investigate the effect of uniaxial flow on the crystallization of polypropylene. Samples were heated to a temperature above the melt temperature to erase their thermal and mechanical histories. The Janeschitz-Kriegl protocol was applied and samples were stretched at various extension rates to a final strain of e = 3.0. Differential scanning calorimetry was applied to crystallized samples to measure the degree of crystallinity. The results showed that a minimum extension rate, corresponding to a Weissenberg number of approximately Wi = 1, is required for an increase in percent crystallization to occur. Below this Weissenberg number, the flow is not strong enough to align the tubes of constrained polymer chains and as a result there is no change in the final percent crystallization. An extension rate was also found for which percent crystallization is maximized. The increase in crystallinity is likely due to flow-induced orientation and alignment of tubes of constrained polymer chains. Polarized-light microscopy verified an increase in number and decrease in size of spherulites with increasing extension rate. Small angle X-ray scattering showed a 7% decrease in inter-lamellar spacing at the transition to flow-induced increase in crystallization. Crystallization kinetics were examined by observing the time required for melts to crystallize under uniaxial flow. The crystallization time decreased with increasing extension rate, even for extension rates where no increase in percent crystallization was observed. These results demonstrate that the speed of crystallization kinetics is greatly enhanced by the application of extensional flow.
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Arora, Deepak. "Structure-property evolution during polymer crystallization." 2010. https://scholarworks.umass.edu/dissertations/AAI3427494.
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The main theme of this research is to understand the structure-property evolution during crystallization of a semicrystalline thermoplastic polymer. A combination of techniques including rheology, small angle light scattering, differential scanning calorimetry and optical microscopy are applied to follow the mechanical and optical properties along with crystallinity and the morphology. Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by time-resolved mechanical spectroscopy, is not caused by packing/jamming of spherulites but by the formation of a percolating network structure. The effect of strain, Weissenberg number (We ) and specific mechanical work (w) on rate of crystallization (nucleation followed by growth) and on growth of anisotropy was studied for shear-induced crystallization of isotactic poly-1-butene. The samples were sheared for a finite strain at the beginning of the experiment and then crystallized without further flow (Janeschitz-Kriegl protocol). Strain requirements to attain steady state/leveling off of the rate of crystallization were found to be much larger than the strain needed to achieve steady state of flow. The large strain and We>1 criteria were also observed for morphological transition from spherulitic growth to oriented growth. An apparatus for small angle light scattering (SALS) and light transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of 20 ms. The experiments were controlled and analyzed with a LabVIEW™ based code (LabVIEW™ 7.1) in real time. The SALS apparatus was custom built for ExxonMobil Research in Clinton NJ.
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Wong, Dávila Jorge Luis [Verfasser]. "Production of ionic liquids through metathesis and melt crystallization / Jorge Luis Wong Dávila." 2009. http://d-nb.info/993833799/34.
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Chen, Chien-Hung, and 陳建宏. "The Effect on Miscibility and Crystallization of PLA/PTT/SEBS by melt blending." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/9yhpmk.
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碩士國立臺北科技大學
有機高分子研究所
98
In this study, organic environmental polymer (PLLA) and new-type textile polymer (PTT) and thermoplastic elastomer (SEBS) were melt-mixed in brabender. The isothermal and nonisothermal crystallization behavior of Poly(L-lactic acid) (PLA) and Poly(Trimethylene Terephthalate) (PTT) blends were investigated with differential scanning calorimetry (DSC). Differential scanning calorimetry (DSC) nonisothermal experiment showed that PLA glass temperature were shift to low temperature when SEBS was added. In isothermal crystallization, the Avrami equation was applied to describe the kinetics of the crystallization in the temperature range of 190~200℃. From isothermal-crystallization analysis, the crystallization rate of PTT were decrease when SEBS was added. Thermal gravimetric (TGA) result showed that the residue of PLA and weight loss temperature was improved with the increase of PTT and SEBS. We also used scanning electron microscopy (SEM) to observe miscibility of each blend, and used polarized-light microscopy (POM) to observe the melt crystallization of PTT after addition of SEBS. In PLA-rich blend, elongation was increased by adding SEBS. In PTT-rich blend, tensile strength was decreased, but elongation was increased when SEBS was added.
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Tähti, Tero [Verfasser]. "Suspension melt crystallization in tubular and scraped surface heat exchangers / von Tero Tähti." 2004. http://nbn-resolving.de/urn:nbn:de:gbv:3-000007337.
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Berry, David J., Colin C. Seaton, W. Clegg, R. W. Harrington, S. J. Coles, P. N. Horton, M. B. Hursthouse, et al. "Applying hot-stage microscopy to co-crystal screening: A study of nicotinamide with seven active pharmaceutical ingredients." 2008. http://hdl.handle.net/10454/4846.
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noCo-crystal screening is routinely undertaken using high-throughput solution growth. We report a low- to medium throughput approach, encompassing both a melt and solution crystallization step as a route to the identification of co-crystals. Prior to solution studies, a melt growth step was included utilizing the Kofler mixed fusion method. This method allowed elucidation of the thermodynamic landscape within the binary phase diagram and was found to increase overall screening efficiency. The pharmaceutically acceptable adduct nicotinamide was selected and screened against a small set of active pharmaceutical ingredients (APIs) (ibuprofen (both the racemic compound (R/S) and S-enantiomer), fenbufen, flurbiprofen (R/S), ketoprofen (R/S), paracetamol, piracetam, and salicylic acid) as part of a larger systematic study of synthon stability. From the screen, three new co-crystal systems have been identified (ibuprofen (R/S and S) and salicylic acid) and their crystal structures determined. Because of poor crystal growth synchrotron radiation was required for structure solution of the S-ibuprofen nicotinamide co-crystal. Two further potential systems have also been discovered (fenbufen and flurbiprofen), but crystals suitable for structure determination have yet to be obtained. A greater ability to control crystallization kinetics is required to yield phase-pure single-crystalline material for full verification of this crystal engineering strategy.
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Kao, Bo Jyue, and 高伯爵. "Biocompatibility, Mechanical, Thermal, and Crystallization Properties of Melt-mixed PLA/SEBS and PTT/SEBSBlends." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/42686035109842892876.
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博士國立臺灣科技大學
材料科學與工程系
103
Poly(lactic acid) (PLA)/styrene-ethylene-butylene-styrene (SEBS) Blends were prepared through melt blending. Differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WXRD) were used to characterize PLA and PLA/SEBS Blends in terms of their melting behavior and crystallization. Curves from thermal gravimetric analysis (TGA) illustrated that the thermostability increased with the SEBS content. Further morphological analysis of PLA/SEBS Blends revealed that SEBS molecules were not miscible with PLA molecules in PLA/SEBS Blends.The tensile testing for PLA and PLA/SEBS Blends showed that the elongation at break was enhanced, but tensile strength decreased with increasing SEBS content. L929 fibroblasts cells were chosen to assess the cytocompatibility; the cell growth of PLA was found to decrease with increasing SEBS content. Possible reasons for these properties of PLA/SEBS Blends were proposed in this study. Poly(trimethyleneterephthalate)(PTT) /styrene–ethylene–buthylene–styrene (SEBS) Blends were prepared by melt compounding. Polarizing optical microscopy was used to observe the spherulitic morphology and the crystal structure of PTT and PTT/SEBS Blends. Scanning electron microscopy was used to determine the dispersion and the compatibility of fracture surfaces of PTT and SEBS. The curves of thermal gravimetric analysis illustrated that the thermo stability decreased with increasing SEBS content. Differential scanning calorimetry was used to investigate the crystallization behavior; the result showed that the glass transition temperature of the compound increased with the SEBS content. The Avrami equation described the isothermal crystallization kinetics. Stress-strain curves for PTT and PTT/SEBS Blends showed that the elongation at break was enhanced with increasing SEBS content.
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Li, Yuan-Hao, and 李元豪. "Study of crystallization and melt for Poly(ethylene terephthalate) on glass transition in CO2." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/63r3nw.
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碩士國立雲林科技大學
化學工程與材料工程研究所
96
Research (PET) in CO2 is on its amorphous region and crystallization morphology and effect of thermal properties. Studying divides into two parts. The first part aims at the discussion, PET of different degree of crystallinities is from behind CO2 annealing, Influence on glass transition temperature (Tg) ; the second part using TMDSC indicated the phenomenon of the crystallization of melting, let out the influence of pressing the speed when with the crystallization, after PET immersed CO2. When PET was in some specific range of degree of crystallinity, it annealed in CO2. PET was that will form two different characteristics are non-crystallization region to coexist: "constrained amorphous and free amorphous". In the research of the second part by the function of TMDSC, we can find PET after dealing with by CO2. Produce in the position of the melting peak " The shoulder shape peak " Phenomenon. And it is influenced that PET is let out the speed of pressing deeply in the course of crystallization, when in the high pressure lets out the speed of pressing fast, between the main crystal controlled by temperature and secondary crystal controlled by CO2, appear one competition state between the two, when letting out the speed of pressing fast, controlled by temperature main crystal too late to form the perfect crystallization, and the high pressure lures a lot of small balls into producing brilliantly again, so, the position of our Revesing song on-line crystallization melting peak in TMDSC (Tm) Can obviously observe the appearance of a pair of melting peak.
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Hong, Cong-Gi, and 洪琮棋. "Crystallization and Miscibility of poly(Trimethylene Terephthalate) and poly(ε-caprolactone) by melt blending." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/am24x4.
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碩士國立臺北科技大學
有機高分子研究所
93
Miscibility and morphology of poly(trimethylene terephthalate) (PTT)/ poly(ε-caprolactone) (PCL) blend were investigated by differential scanning calorimeter (DSC) , polarized-light microscopy (POM) , scanning electron microscopy (SEM) and wide-angle X-ray diffraction(WAXD) . Two distinct glass transition temperatures (Tg) could be observed by of DSC . The upper Tg around 45℃ , was close to that of neat PTT , and the lower Tg around -65℃ , was close to that of neat PCL . The POM and SEM results indicated two separate morphology . According to these results , PTT/PCL should be immiscible . There was ring-banded spherulites with Malteses-cross patterns observed in neat PTT . Ferthermore , the crystallization tempterature of PTT was first increased then decreased the increase of PCL content .The degree of crystallization of PCL was increased with the increase of PTT , which was obsearved in PTT . The DSC isothermal crystallization at various crystallization temperatures has been applied for PTT/PCL systems . Crystallization kinetics was determined by the Avrami equation. The Flory-Huggins interaction parameter, χ12, for PTT/PCL blend was determined to be －0.25576 through the melting point depression analysis, indicateing partial miscibility in blends of PTT and PCL. The flod surface interfacial free energy and crystal lamellar thickness have been estimated by Hoffman-Lauritzen equation and Thompson-Gibbs equation. By XRD, we found crystal size and degree of crystallinity of PCL decrease with the increase of heating time.
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Chu, Yi Hsuan, and 朱奕宣. "A study on the growth kinetics and purification of acrylic acid in melt crystallization." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/mg6v22.
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碩士長庚大學
化工與材料工程學系
106
The growth kinetics of acrylic acid (AA) with the impurity of propanoic acid (PA) or acetic acid(AC) are studied in this work at various cooling temperatures for solid-layer melt crystallization. The two-step growth model is adopted to investigate the growth rates of AA. Freundlich adsorption isotherm is applied to study the effects of PA or AC on the final purity of AA crystal layer. Consequently, the heat of adsorption for the incorporation of PA or AC onto the AA crystal lattice is determined respectively. The relationship between the effective distribution coefficient and the growth rate is also discussed for the AA melt with the impurity of PA or AC.