کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1580089 | 1645418 | 2009 | 4 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Secondary relaxations in heterocyclic polymer networks: A study of mechanical spectroscopy
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
دانش مواد (عمومی)
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Experiments of differential scanning calorimetry and dynamic mechanical spectroscopy on linear and cross-linked heterocyclic polymer networks (HPNs) have been performed over the temperature range between 120 and 400 K. The temperature dependences of the storage modulus Eâ² and the internal friction Qâ1 of HPNs, investigated by mechanical waves of frequencies ranging between 0.3 and 30 Hz, reveal anelastic behaviors which are mainly governed by the secondary β- and primary α-relaxations. The addition of cross-links in an apparently linear polymer network was accompanied by the shift of the glass transition to higher temperatures. Differently from the α-relaxation whose strength decreases with cross-linking, the β-relaxation strength increases. This observation implies the lack of any dynamical hierarchy between the local and cooperative segmental dynamics in these systems. The β-relaxation follows the Arrhenius law with values of the characteristic frequency Ï0 and the activation energy Eact ranging between 1015 and 1016 sâ1 and 43.7 and 48.7 kJ/mole, respectively. In both the HPNs the β-loss peaks have been quantitatively analyzed by the symmetric double-well potential (SDWP) model.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: A - Volumes 521â522, 15 September 2009, Pages 251-254
Journal: Materials Science and Engineering: A - Volumes 521â522, 15 September 2009, Pages 251-254
نویسندگان
Giovanni Jr, Giuseppe Carini, Sergio La Rocca, Gaspare Tripodo, Antonio Bartolotta, Gaetano Di Marco, Eleonora G. Privalko,