کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5190648 | 1381213 | 2006 | 9 صفحه PDF | دانلود رایگان |
Cubic specimens of a semicrystalline poly(butylene terephthalate) (PBT) have been compressed up to post-yield deformation levels with a fast (3.0 Ã 10â2 sâ1) and a slow (1.5 Ã 10â4 sâ1) strain rate at three different temperatures (25 °C, 45 °C, and 100 °C, i.e. below, close and above the glass transition temperature of the material, Tg, respectively). Differently from literature results reported for amorphous polymers, semicrystalline PBT shows that, after a post-yield deformation, recovery occurs also at temperatures higher than Tg, and that an irreversible deformation, Éirr, is set in the material. The irreversible strain component has been evaluated as the residual deformation after a thermal treatment of 1 h at 180 °C.After unloading, isothermal strain recovery has been monitored for time periods of 1 h at various temperatures. From the obtained data, strain recovery master curves have been constructed by a time-temperature superposition scheme. The features of the recovery process for the various deformation conditions have been analysed. In particular, it appears that specimens deformed below Tg show a lower irreversible component, whereas, when deformed above Tg, they display a higher irreversible deformation and a slower recovery process. Moreover, the effect of deformation rate appears particularly marked for samples deformed above Tg.
Journal: Polymer - Volume 47, Issue 16, 26 July 2006, Pages 5862-5870