کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5184622 | 1381052 | 2010 | 8 صفحه PDF | دانلود رایگان |
Deformation-induced phase transition behavior of polyamide 12 (PA12) in its segmented copolymers with polytetrahydrofuran (PTHF) was studied with in-situ wide angle X-ray scattering (WAXS) at different temperatures. In these segmented copolymers, which contain a high content of PTHF, a transformation from the stable γ phase to a metastable αⳠphase is observed during tensile deformation at room temperature, which shows a similar diffraction behavior to that of the α phase but without an obvious melting point. The deformation-induced αⳠphase is not a thermodynamic stable phase but arises from kinetic origins, which is in line with the condition for its formation. After the release of tensile force following deformation, the metastable αⳠphase can partially transform back to the initial γ phase. The reversible phase nature may contribute somewhat to the elasticity of PTHF-PA12 systems as a result of this enthalpic contribution. Upon increasing the content of PTHF in the copolymer, the critical stress required to induce the new αⳠphase increases. Upon increasing strain, the αⳠphase will disappear in the samples that possess a particularly high content of PA12. Higher temperatures also prevent the γ phase from transforming to the αⳠphase.
Journal: Polymer - Volume 51, Issue 23, 29 October 2010, Pages 5604-5611