Thermal behavior of aromatic polyamic acids and polyimides containing oxadiazole rings |
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Authors: | Mariana Cristea Daniela Gheorghiu Ionita Maria Bruma B. C. Simionescu |
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Affiliation: | (1) Petru Poni’ Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700487 Iasi, Romania;(2) Department of Natural and Synthetic Polymers, ‘Gh. Asachi’ Technical University, 700050 Iasi, Romania |
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Abstract: | Two aromatic polyimides and the corresponding poly(amic acid)s, with oxadiazole and para/meta phenoxyphenylene rings in the backbone, were synthesized and the structure — thermal properties correlation was followed by dynamic mechanical analysis. Concerning the poly(amic acid)s, the glass transition domain was emphasized only for the compound with meta-oriented rings because the process of imidization takes place with increasing temperature. A multiplex experiment was performed to calculate the activation energy of the transition localized under 200°C. Consecutive heating-cooling-heating cycles were accomplished. All phenomena are discussed by cross-examination of the storage modulus (E′), loss modulus (E″) and loss factor tanδ variation with temperature. |
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Keywords: | aromatic poly(amic acid)s dynamic mechanical analysis polyimides oxadiazole rings |
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