Please use this identifier to cite or link to this item: http://hdl.handle.net/1822/12594

TitleNanostructure evolution during unixial deformation of PET : a simultaneous WAXS and SAXS study using synchrotron radiation
Author(s)Viana, J. C.
Mano, J. F.
Denchev, Z.
Oliveira, M. J.
Cramez, M. C.
KeywordsNanostructure evolution
PET
SAXS and WAXS
Deformation mechanisms
Issue date2006
PublisherTrans Tech Publications Ltd
JournalMaterials Science Forum
Abstract(s)In this work, the structural evolution and damage of PET during stretching is assessed by wide- and small-angle X-ray scattering (respectively, WAXS and SAXS) experiments in specimens pre-deformed at different strain levels (ex-situ characterization). Injection moulded PET rectangular tensile specimens were stretched (at 2 mm/min) into the plastic domain in a universal test machine at different strain levels at room temperature. The structure of the central zone of the deformed specimens was then characterized by WAXS and SAXS experiments using an X-ray synchrotron source. PET was initially (before stretching) amorphous. A strong molecular orientation in the stretching direction is quickly developed for the initial plastic deformation levels, evidenced by strong equatorial WAXS reflections. This orientation rapidly levels off, remaining constant during further stretching. The WAXS patterns are accompanied with no reflections on SAXS, evidencing a local ordering phenomenon, typical of nematic liquid-crystalline structures. The SAXS patterns evidence the occurrence of some voiding in the cold drawing regime just after yielding. These anisotropic voids are oriented perpendicular to the stretching direction, as in a craze-like structure. The void size drastically increases at the onset of the strong strain hardening behaviour.
TypeConference paper
URIhttp://hdl.handle.net/1822/12594
ISBN9780878494026
ISSN0255-5476
Peer-Reviewedyes
AccessRestricted access (UMinho)
Appears in Collections:IPC - Artigos em revistas científicas internacionais com arbitragem

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