The thermodynamics of uniaxial solid deformation was studied experimentally for a number of polymeric solids, including two polyurethane-urea elastomers, natural rubber, a thermoplastic elastomer and low density polyethylene. A deformation calorimeter was developed to measure the heat and work of uniaxial solid deformation and measurements were made on the above materials. A differential scanning calorimetry method was developed to characterize the melting behavior of stretched elastomers which were found to undergo stress-induced crystallization during stretching as deduced from the large but recoverable internal energy changes measured by deformation calorimetry during uniaxial extension and contraction. Wide angle x-ray diffraction and thermostatic measurements were also performed on the elastomers held in the extended state in order to characterize the amorphous-crystalline phase transition which occurs during deformation. The motivation for this work was to evaluate the performance of the two polyurethane-urea elastomers which were found to function effectively as working substances in rubber heat engines. These elastomers could generate 1 Joule of work per gram of elastomer at about 3% of Carnot efficiency in experimental Sterling cycles.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-6920 |
| Date | 01 January 1985 |
| Creators | LYON, RICHARD E |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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