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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"polymer crystallization"”.
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Online polymer crystallization experiment
An architecture for online remote operation of a polymer crystallization experiment was refined, beta tested in actual use conditions, and extended based on feedback from those tests. In addition, an application for graphically simulating macroscopic crystal spherulite growth was developed for use …
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Order phenomena in polymer crystallization
… these thesis the influence of order phenomena in polymer melts on crystallization kinetics has been investigated by means of nuclear magnetic resonance (NMR) spectroscopy. In particular the so-called memory effect in syndiotactic polypropylene (s-PP) and the influence of entangled polymer chains …
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Heterogeneous nucleation in polymer crystallization
… the study of the interfacial layer between the polymer and the substrate of densely packed particles using light microscopy and by quantitative analysis of the DSC cooling exotherms, obtained from polymers with homogeneously dispersed nucleating agent. It has been found that the crystallisation …
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Polymer Crystallization: Polycarbonate and Polybutene-1
The crystallization of polycarbonate from the glassy state was examined using thin ($\sim$1000A), solution cast films and thicker (0.16 and 1.5 mm) compression molded films. A detailed study of the crystallization process in the thin films, as observed by transmission electron microscopy, revealed …
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Remote microscope for Polymer Crystallization WebLab
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
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Polymer Crystallization: Micro- and Nano- Filler Effects on Isotactic Polypropylene
… composites and blends. The preparation of polymer blends is an important technique in order to modify the target property of an individual polymer according to the requirement of the application field. Since the features of semi-crystalline polymers depend on the crystallinity degree and …
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On-line laboratory for remote polymer crystallization experiments using optical microscopy
… in which students remotely conduct and analyze polymer crystallization experiments using a polarized light microscope under controlled temperature conditions. The Polymer Crystallization iLab involves melting a polymer sample and subsequently cooling it down to a temperature below its melting …
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Molecular modeling of polymer crystallization and the effect of nucleating agents
The microstructure in a semicrystalline polymer material ultimately determines its material properties. Despite the abundance of research into the semicrystalline microstructure and its evolution during crystallization, a clear description of its development remains elusive. The advent of advanced …
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Effect of chain structure on the thermodynamics and kinetics of polymer crystallization
… (LH) secondary nucleation barrier model of polymer crystallization. One of the major criticisms of the LH theory was that it predicted divergence of the lamellar thickness and crystal growth rate at finite undercoolings - the so-called “δ𝑙 catastrophe." Within this work, it has been shown …
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Self-Consistency of the Lauritzen-Hoffman and Strobl Models of Polymer Crystallization Evaluated for Poly(ε-caprolactone) Fractions and Effect of Composition on the Phenomenon of Concurrent Crystallization in Polyethylene Blends
… rate conditions suggested that the isothermal crystallization of the samples should be used for a proper evaluation of the molecular weight dependence of the observed melting temperature and degree of crystallinity in PCL. The molecular weight and temperature dependence of the spherulitic …
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A study of the crystallization kinetics of isotactic polystyrene
… of the Lauritzen-Hoffman kinetic theory of polymer crystallization. The primary objectives of the study are to critically test the Lauritzen-Hoffinan theory under conditions not rigorously investigated before and to gain a better understanding of the molecular weight dependence of crystal …
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Molecular simulation of crystal growth in alkane and polyethylene melts
… powerful tool for understanding the process of polymer crystallization. By using carefully constructed simulations, one can independently observe the two phenomena responsible for melt crystallization: nucleation and growth. This research focuses on modeling the growth process using potentials …
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Supramolecular polymer additives to improve the crystallization behavior and optical properties of polybutylene terephthalate and polyamides
… the property profile of commercial thermoplastic polymers. The physico chemical properties of semi crystalline polymers depend to a large extend on the crystal structure and spherulite size, which can be controlled by nucleating agents. These additives can increase the crystallization temperature …
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Advanced techniques for chemical gradient, eutectic metal, and crystallized polymer film additive manufacturing
… printing technique to manufacture crystallized polymer films is described. The slot die printing head is of a novel design, using microstructures etched into the head to induce specific flows that cause polymers to crystallize. Two systems are either built or adapted for this printing technique. …
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Molecular simulation of nucleation from flowing polymer melts
… flow drastically accelerates the kinetics of polymer crystallization, altering the morphology and properties of the resulting material The earliest stage of flow-induced crystallization, known as flow-enhanced nucleation (FEN), is challenging to study experimentally due to the small …
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Chemical and Physical Modifications of Semicrystalline Gels to Achieve Controlled Heterogeneity
… low cost. Specifically, sulfonated multiblock copolymers are attractive because their phase-separated morphologies aide in facile proton transport. In this work, the functionalization of semicrystalline gels of poly(ether ether ketone) (PEEK) is explored as a novel post-polymerization method to …
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Phase Behavior of Poly(Caprolactone) Based Polymer Blends As Langmuir Films at the Air/Water Interface
… studied as a model system for investigating polymer crystallization. In this thesis, PCL crystallization along with other phase transitions in PCL-based polymer blends are studied as Langmuir films at the air/water (A/W) interface. In order to understand the phase behavior of PCL-based …
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Dynamic-template-directed crystallization of semiconducting polymers for organic electronics
Solution processable semiconducting polymers have been under intense investigations due to their potential applications in large-area printed electronics from solar cells to biomedical devices. However, controlling the multiscale morphology and device performance of printed polymer thin films …
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LAWS OF LARGE NUMBERS AND CENTRAL LIMIT THEOREMS FOR RANDOM GEOMETRIC MEASURES. A COMPUTATIONAL APPROACH
… A.Micheletti, C.Salani, Mathematical models for polymer crystallization processes. In Mathematical Modelling for Polymer Processing (V. Capasso, Ed). Springer, Heidelberg, 2000, 167-242. [4] M. D. Penrose, Gaussian limits for random geometric measures. Electronic Journal of Probability 12, 2007, …
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Effect of Laser Induced Crystallinity Modification on Degradation and Drug Release of Biodegradable Polymer
Biodegradable polymers such as poly(L-lactic acid) (PLLA) are promising in drug delivery applications. In biodegradable polymer-based drug delivery systems, drugs are released at a rate determined by polymer degradation. Polymer degradation exhibits an undesirable induction period, during which a …
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