Yang, Junyu
(2020)
Irreversible Effects in Thin Film Buckling and Development of a High Temperature Thermoplastic Foam.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Three projects in total are involved in this dissertation. They are: (1) Compression-induced fold localization of thin films bonded to viscous substrate. (2) Stretching-induced wrinkling in plastic-rubber composites. (3) The preparation and thermomechanical properties of high temperature PPEK foams.
In the study of irreversible effects in the thin film buckling. Two projects would be covered: (1) Compression-induced fold localization of thin films bonded to viscous substrate. The basic idea is as following: the viscous liquid is layered on a prestretched rubber substrate, and a strip of film is then placed on the surface of the liquid. Releasing the rubber substrate at a well-controlled rate imposes compressive stress on the liquid, which in turn compresses the film and induces buckling at the free surface. In this project, the following work would be discussed in detail: 1) how the experiments are implemented: self-designed and set up of the experiments and digital image correlation analysis approach for video data processing; 2) analysis the effect of releasing rate of the rubber and liquid layer thickness to the system. (2) Stretching-induced wrinkling in plastic-rubber composites. In this study, the mechanics of three-layer composite films composed of an elastomeric layer sandwiched between two thin surface layers of plastic is studied. Upon stretching and releasing such composite films, they develop a highly wrinkled surface texture. This approach to realizing highly wrinkled textures offers several advantages, most importantly the fact that high aspect ratio wrinkles (amplitude to wavelength ratios exceeding 0.4) can be realized.
At last, In the study of the preparation and thermomechanical properties of high temperature PPEK foams, the following work would be shown in detail: 1) develop a foaming process to convert phthalazinone-based polymers into foams of various densities; 2) evaluate the density, microstructure, mechanical and thermal properties of the foams. And specifically, thermal conductivity and modulus of the foam will be measured as a function of their density.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
3 August 2020 |
| Date Type: |
Publication |
| Defense Date: |
November 2019 |
| Approval Date: |
3 August 2020 |
| Submission Date: |
12 November 2019 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
108 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
wrinkling, folds, plastic-rubber composites, viscous substrate, high temperature foams, PPEK, phthalazinone-based polymers , thermomechanical properties |
| Date Deposited: |
03 Aug 2021 05:00 |
| Last Modified: |
03 Aug 2021 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/37772 |
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