This work focuses on polymer glasses relaxation behavior. Polymethylmethacrylate was chosen as a typical representative of polymer glasses. Relaxation processes were studied by dynamical mechanical spectroscopy and differential scanning calorimetry was used as a supplemental analysis. Relaxation process above Tg and high values of rubberlike plateau modulus were observed in thermomechanical spectra. High temperature relaxation transition was studied from the perspective of thermal history, frequency and axial stress dependence and influence of molecular structure was also investigated. Apparent activation energies of studied processes and their axial stress dependence for polymethylmethacrylate were determined. On the basis of obtained data, a hypothesis was developed which connects high temperature relaxation process with molecular process responsible for strain hardening.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:217006 |
| Date | January 2014 |
| Creators | Ondreáš, František |
| Contributors | Kučera,, Jaroslav, Jančář, Josef |
| Publisher | Vysoké učení technické v Brně. Fakulta chemická |
| Source Sets | Czech ETDs |
| Language | Slovak |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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