Global ETD Search
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 12 of 12 for “"equilibrium melting temperature"”.
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Equilibrium Melting Temperature Determination of Semicrystalline Polymers through Nonlinear Hoffman-Weeks Extrapolation and Secondary Crystallization of Ethylene/Styrene Copolymers
… extrapolation for the determination of the equilibrium melting temperatures of semicrystalline polymers is critically reviewed. It is shown that the linear extrapolation of observed melting temperatures cannot, in general, provide a reliable estimate of the equilibrium melting temperature. A …
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Morphology and Properties of Amorphous Polyethylene Terephthalate
… (ANGSTROM)) was ultraquenched from above its equilibrium melting temperature. Sufficiently rapid quenching rate below T(,g) and heating above the critical temperature before quenching were identified as necessary conditions to produce uniform morphology. Under other conditions, a conventional …
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Crystallization and Melting Studies of Poly(ε-caprolactone) and Poly(ethylene oxide) using Flash™ Differential Scanning Calorimetry and Preparation and Characterization of Poly(δ-valerolactone) Fractions
The isothermal crystallization and melting temperatures of poly(ε-caprolactone) were correlated using fast differential scanning calorimetry. The melting kinetics was found to be independent of isothermal crystallization temperature and time. The conventional Hoffman-Weeks method could not be used …
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Numerical stimulation of stress-induced crystallization of injection molded semicrystalline thermoplastics
… orientation of polymer chains increase the melting temperature of the plastics, and hence, the supercooling which is the driving force for crystallization. By assuming that the effect of stress on crystallization is only by increasing the equilibrium melting temperature, the basic quiescent …
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A Study of Crystallization in Bisphenol-A Polycarbonate
… change when quenched below its glass transition temperature, enabling the study of different stages of crystallization through the frozen morphology. The study of the initial stages of crystallization pertained to crystallization times prior to the growth of detectable crystallinity. This study …
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Crystallization Behavior, Tailored Microstructure, and Structure-Property Relationships of Poly(Ether Ketone Ketone) and Polyolefins
… determine the fundamental thermodynamic value of equilibrium melting temperature (Tmo) for the semi-crystalline polymer poly(ether ketone ketone) (PEKK), 2) increase understanding of the influence of microstructure (random versus blocky) of functionalized semi-crystalline polymers on physical and …
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Morphology, Crystallization and Melting Behavior of Propylene-Ethylene Statistical Copolymers
In this work the morphology, crystallization and melting behavior of novel Dow Chemical propylene-ethylene copolymers were investigated. The incorporation of ethylene units into a polypropylene chain resulted in the decrease in crystallization, melting and glass transition temperatures and overall …
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A study of the crystallization kinetics of isotactic polystyrene
… growth rate measurements were extended to higher temperatures and a more appropriate kinetic equation for crystal growth rate analysis was applied. The majority of published studies that have used the Lauritzen-Hoffman theory applied an approximated form of the kinetic equation which does not …
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Effect of chain structure on the thermodynamics and kinetics of polymer crystallization
… front are known a priori. Crystal growth and melting behavior were studied in the case of linear and cyclic polydimethylsiloxanes. An equilibrium melting temperature (T<sub>m</sub>) of 250K was determined by the Hoffman-Weeks extrapolation method for a linear PDMS fraction with …
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On the Melting and Crystallization of Linear Polyethylene, Poly(ethylene oxide) and Metallocene Linear Low-Density Polyethylene
The crystallization and melting behaviors of an ethylene/1-hexene copolymer and series of narrow molecular weight linear polyethylene and poly(ethylene oxide) fractions were studied using a combination of ultra-fast and conventional differential scanning calorimetry, optical microscopy, small angle …
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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
… pair. Calorimetric studies of the melting behavior of fractions that were crystallized either isothermally or under constant cooling rate conditions suggested that the isothermal crystallization of the samples should be used for a proper evaluation of the molecular weight dependence …
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Mixed-Phase Solidification of Thin Silicon Films on Silicon Dioxide
… system to directly observe and understand melting and solidification during the MPS process. Additionally, in order to investigate the grain boundary melting phenomenon, we have conducted "rapid-quench" demarcation experiments and established a one-to-one correspondence between the in situ …