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Full-Text Articles in Engineering

Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani Dec 2014

Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani

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The work in this dissertation is devoted to the synthesis and characterization of novel materials for off-line unattended sensing: shape-memory grafted nanofoams. The fabrication process and characterization of highly efficient, polymeric nanosensor element with the ability to selectively detect analytes and retain memory of specific exposure events is reported. These shape memory nanofoams could potentially act as efficient and highly sensitive coatings for evanescent waveguide-based optical monitoring systems. On exposure to specific analytes, the polymeric coatings locally change their internal structure irreversibly at the nanolevel, affecting the local optical properties such as refractive index. Currently, enrichment polymer layers (EPLs) are …


Thermally Responsive Polymer Electrolytes For Inherently Safe Electrochemical Energy Storage, Jesse Kelly Dec 2014

Thermally Responsive Polymer Electrolytes For Inherently Safe Electrochemical Energy Storage, Jesse Kelly

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Electrochemical double layer capacitors (EDLCs), supercapacitors and Li-ion batteries have emerged as premier candidates to meet the rising demands in energy storage; however, such systems are limited by thermal hazards, thermal runaway, fires and explosions, all of which become increasingly more dangerous in large-format devices. To prevent such scenarios, thermally-responsive polymer electrolytes (RPEs) that alter properties in electrochemical energy storage devices were designed and tested. These RPEs will be used to limit or halt device operation when temperatures increase beyond a predetermined threshold, therefore limiting further heating. The development of these responsive systems will offer an inherent safety mechanism in …


Microanalysis Of Polymer Chain Diffusion In Heat Seals, Russell Cooper Dec 2014

Microanalysis Of Polymer Chain Diffusion In Heat Seals, Russell Cooper

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Heat sealing is an integral method for the closure and protection of packaging. Previous work has shown that seal strength is developed by the interdiffusion of polymer chains within heat seals. Heat seals were made between two dissimilar materials. Poly(ethylene-co-acrylic acid) (EAA) was heat sealed to ionomer. Diffusion within the EAA-ionomer heat seals was estimated. The diffusion estimates were then related to resulting seal strength in the EAA-ionomer sealant system. Heated tooling sealing was utilized to make heat seals at 40 psi (275.79 kPa), 0.5 seconds, and a range of temperatures between 180˚F (82.22˚C) and 300˚F (148.89˚C). Scanning electron microscopy …


High-Productivity Membrane Adsorbers: Polymer Surface-Modification Studies For Ion-Exchange And Affinity Bioseparations, Heather Chenette Aug 2014

High-Productivity Membrane Adsorbers: Polymer Surface-Modification Studies For Ion-Exchange And Affinity Bioseparations, Heather Chenette

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This Dissertation centers on the surface-modification of macroporous membranes to make them selective adsorbers for different proteins, and the analysis of the performance of these membranes relative to existing technology. Traditional chromatographic separations for the isolation and purification of proteins implement a column packed with resin beads or gel media that contain specific binding ligands on their exposed surface area. The productivity of this process is balanced by the effective use of the binding sites within the column and the speed at which the separation can take place, in addition to the need to maintain sufficient protein purity and bioactivity. …