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Full-Text Articles in Engineering Science and Materials
Analyses Of Densely Crosslinked Phenolic Systems Using Low Field Nmr, Jigneshkumar Patel
Analyses Of Densely Crosslinked Phenolic Systems Using Low Field Nmr, Jigneshkumar Patel
Doctoral Dissertations
A uniform dispersion of reactants is necessary to achieve a complete reaction involving multi-components, especially for the crosslinking of rigid high-performance materials. In these reactions, miscibility is crucial for curing efficiency. This miscibility is typically enhanced by adding a third component, a plasticizer. For the reaction of the highly crystalline crosslinking agent hexamethylenetetramine (HMTA) with a strongly hydrogen-bonded phenol formaldehyde resin, furfural has been traditionally used as the plasticizer. However, the reason for its effectiveness is not clear. In this doctoral thesis work, miscibility and crosslinking efficiency of plasticizers in phenolic curing reactions are studied by thermal analysis and spectroscopic …
Dynamic Range Limitations Of Low-Noise Microwave Transistors At Cryogenic Temperatures, Ahmet Hakan Coskun
Dynamic Range Limitations Of Low-Noise Microwave Transistors At Cryogenic Temperatures, Ahmet Hakan Coskun
Doctoral Dissertations
Dynamic range is an important metric that specifies the limits of input signal amplitude for the ideal operation of a given receiver. The low end of dynamic range is defined by the noise floor whereas the upper limit is determined by large-signal distortion. While dynamic range can be predicted in the temperature range where compact transistor models are valid, the lack of large-signal models at temperatures below -55 C prevents the prediction and optimization of dynamic range for applications that require cryogenic cooling. For decades, the main goal concerning the performance of these applications was lowering the noise floor of …