Thesis
GENERALIZED EQUATIONS OF STATE AND FUNDAMENTAL RELATIONS FOR THE THERMAL AND STRAIN RESPONSE OF PHOTOMECHANICAL MATERIALS
Washington State University
Master of Science (MS), Washington State University
05/2025
DOI:
https://doi.org/10.7273/000007372
Abstract
This thesis outlines two models for a thermodynamic equation of state for the force as a function of temperature and sample elongation for elastic materials. The first extends
Hooke’s law to include a temperature dependent compliance (inverse of spring constant) to account for softening and rest length to account for thermal expansion. The second
originated from an empirical expression that describes the thermal force behavior, where the material’s length dependence is added in a way that conforms with the expected behavior. The thermodynamic fundamental relation, which contains all information about a system and connects measurable properties to abstract but more fundamental ones, is determined from the equations of state. The Helmholtz potential is derived for both models and a Legendre transform to the internal energy can be derived analytically for the first equation of state model, but can only be estimated for the second model. The equations of state are compared to experimental force data for dye-doped glassy polymer and cross-linked liquid crystal network samples. While the first model fits to the experimental data, an interpretation of the fit parameters concludes that it contradicts the known underlying mechanisms in polymers. The second model both fits the experimental data and maintains the prediction that thermal expansion is the leading mechanism in the thermal force. Additionally, column buckling is investigated as a tool for interpreting force versus sample extension data and calibrating the force sensor used to collect the experimental data - a requirement for future experiments. This thesis thus provides models that can be applied to study the mechanisms of the photomechanical response in a variety of materials.
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Details
- Title
- GENERALIZED EQUATIONS OF STATE AND FUNDAMENTAL RELATIONS FOR THE THERMAL AND STRAIN RESPONSE OF PHOTOMECHANICAL MATERIALS
- Creators
- Emily Frank
- Contributors
- Mark Kuzyk (Chair)Fred Gittes (Committee Member)Brian Collins (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Physics and Astronomy
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 56
- Identifiers
- 99901221148801842
- Language
- English
- Resource Type
- Thesis