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Showing 1 to 20 of 22 for “"Spherulite"”.
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Polymer structure and property studies in elongational rheology, spherulite deformation, and biaxial strain induced crystallization
… textures were consistent with classic spherulite growth mechanisms and structure theories. Uniaxial deformation of a single spherulite was successfully studied in a model system consisting of isolated spherulites embedded in an amorphous polymer matrix. By isolating the spherulite, the …
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The effects of ionising radiation on polypropylene
… oxide are reported.. The melting temperatures, spherulite growth rates, and isothermal crystallisation rates of irradiated polypropylene are compared to those of the non-irradiated polymer. Crystallisation is found to proceed with an Avrami integer n = 2. At a given crystallisation temperature, …
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Online polymer crystallization experiment
… for graphically simulating macroscopic crystal spherulite growth was developed for use as an educational tool. Finally, the experiment was used in the design process for modifying the generic iLab framework to incorporate interactive functionality. Specifically, a reservation model and design …
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Crystallization behavior and morphological features of two LARC polyimides and local orientation studies of two semicrystalline model composites
… However, the sign of the isotactic polypropylene spherulite orientation function values was the opposite of what was anticipated. These results were considered in light of spherulite W AXS data also obtained.
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Novel polypropylene based microporous membranes via spherulitic deformation
… processing condition. A tangential lamellae-rich spherulite was created and identified with a positive birefringence sign. A sequential annealing process improved the crystalline structure, and in particular the thickness of the tangential lamellae. The annealing process proved to be critical for …
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A numerical and experimental investigation of the effects of thermal history on the structure/property relationship of PPS/carbon fiber composites
… (both amount of crystallinity and the size of spherulites) which arise during the cooling of a slab of a semicrystalline polymer reinforced with long continuous carbon fibers. This situation is commonly found during the processing of semicrystalline thermoplastic composites. Whereas published …
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Field induced orientation of semicrystalline and non-crystallne block copolymer microdomain patterns
… to the cylinder axis, completely suppressing spherulite formation. Microdomain structures of block copolymers are also controlled in thin films by directional solidification of a crystallizable solvent. This new method is based on the use of crystalline organic materials, which are solvents …
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Heterogeneous nucleation in polymer crystallization
… found to be related to the initial number of spherulites present in the un-nucleated polymer. The highest shift in the crystallization temperature has been obtained from partially molten polymers (self nucleation); the shift which can be obtained with the best nucleating agents is approaching …
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Relationships between micromorphology and impact properties of injection moulded isotactic polypropylene
… degree of orientation, crystal form (α or β) and spherulite size of the various layers were found to be strongly dependent on the moulding parameters and additives incorporated. The role of such factors in determining the impact properties was identified providing valuable information to …
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Determining the role of charges in ionic polymer blend systems
… kinetics were studied quantitatively via POM spherulite measurements over time and agreed with DSC data. GI-WAXS showed that the blends displayed crystalline features from both the individual components. The second study presented in this thesis focuses on amorphous charged blends. The blends …
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Novel pillar formation in evaporating poly(ethylene oxide) droplets
… to be driven by the formation of a contracting spherulite collar around the droplet's 3-phase contact line. If the liquid base radius recedes quickly enough compared with the height reducing effects of the evaporation, the growing solid deposit eventually lifts the droplet from the surface, …
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Quantum Imaging of Biosamples
… precise, state-of-the-art engineering. Polymer spherulites, naturally occurring birefringent crystals that grow around defects in a radial pattern, are an example of this. We show through the example of ascorbic acid, commonly referred to as Vitamin C, that spherulites are capable of creating …
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Mechanistic insights into the aggregation of [beta]-amyloid
… on aggregate morphology, in conformity with spherulite formation.
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A study of miscibility, morphology, crystallization and melting behavior of isotactic poly(propylene) in blends of poly(propylene) and poly(1-butene)
… the glass transition behavior, morphology, spherulite growth rate and melting behavior of PP/PB1 blends with different molecular weights and tacticities have been investigated. Dynamic mechanical analysis on the melt blends of isotactic polypropylene and poly(1-butene) (it-PP/it-PB1), made …
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Study of the Morphology and Optical Properties of Propylene/Ethylene Copolymer Films
… properties, presumably through a change in the spherulite birefringence. The bulk haze, clarity, and transparency of a homopolymer film were degraded through annealing treatments, which decreased the fraction of gamma-phase crystallinity and increased the thickness of existing lamellae, …
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The chemical characterisation of authigenic carbonates from the Witbank no. 2 coal seam : environmental and diagenetic implications
… conditions prevailing during precipitation. Spherulite chemistry is largely representative of the continuation of alkaline conditions with high sulphate supply. Those forming closer to palaeohighs are sideritic and possibly reflect the input of fresher run-off water, allowing more acidic …
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Morphological Studies of Crystallization in Thin Films of PEO/PMMA Blends
… 30 wt% PEO, the crystal morphology varied from spherulites to needles and dendrites. Variation of the crystallization temperature and PMMA molecular weight resulted in similar changes in morphology. A morphological map demonstrating the roles of the experimental controls on the observed crystal …
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Tensile and fracture behaviour of isotropic and die-drawn polypropylene-clay nanocomposites. Compounding, processing, characterization and mechanical properties of isotropic and die-drawn polypropylene/clay/polypropylene maleic anhydride composites
… isotropic or oriented polymer matrix. Control of spherulite size, silicate layer d‑spacing, and nanoparticle distribution—particularly the presence of intercalated microtactoids with possible semi‑exfoliated structures—has been suggested as key to optimising the final properties of PPNCs.
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On the Melting and Crystallization of Linear Polyethylene, Poly(ethylene oxide) and Metallocene Linear Low-Density Polyethylene
… of the lateral surface free energy. Analysis of spherulite growth rate and wide angle X-ray diffraction data for 26 linear polyethylene and 5 poly(ethylene oxide) fractions revealed that the undercooling at the regime I/II transition, the equilibrium fold surface free energy, the strength of the …
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Microfluidic formation of hierarchical micro and nano emulsions for biomedical applications
… of protein phase transitions, such as fibril, spherulite and crystal formation, without resorting to extrinsic fluorophores, paving the way for a label-free method to monitoring self-assembly events. In order to fully explore the potential of observing such events in a massively parallel way, I …
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