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2010

University of Massachusetts Amherst

Rheology

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Full-Text Articles in Engineering

Structure-Property Evolution During Polymer Crystallization, Deepak Arora Sep 2010

Structure-Property Evolution During Polymer Crystallization, Deepak Arora

Open Access Dissertations

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 …


Water-In-Oil Microemulsions: Counterion Effects In Aot Systems And New Fluorocarbon-Based Microemulsion Gels, Xiaoming Pan Feb 2010

Water-In-Oil Microemulsions: Counterion Effects In Aot Systems And New Fluorocarbon-Based Microemulsion Gels, Xiaoming Pan

Open Access Dissertations

Microemulsions have important applications in various industries, including enhanced oil recovery, reactions, separations, drug delivery, cosmetics and foods. We investigated two different kinds of water-in-oil microemulsion systems, AOT (bis(2-ethylhexyl) sulfosuccinate) microemulsions with various counterions and perfluorocarbon-based microemulsion gels with triblock copolymers. In the AOT systems, we investigated the viscosity and interdroplet interactions in Ca(AOT)2, Mg(AOT)2 and KAOT microemulsions, and compared our results with the commonly-studied NaAOT/water/decane system. We attribute the differences in behavior to different hydration characteristics of the counterions, and we believe that the results are consistent with a previously proposed charge fluctuation model. Perfluorocarbons (PFCs) are of interest …