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Rheo‐Optical Fourier TransformRaman Study of the Conformational Changes in Uniaxially Stretched Amorphous Bulk Poly(ethylene terephthalate)
Author(s) -
RodríguezCabello J. C.,
Merino J. C.,
Fernández M. R.,
Pastor J. M.
Publication year - 1996
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199601)27:1<23::aid-jrs918>3.0.co;2-t
Subject(s) - fourier transform infrared spectroscopy , amorphous solid , glass transition , materials science , crystallization , raman spectroscopy , ethylene glycol , ethylene , poly ethylene , spectroscopy , deformation (meteorology) , polymer , chemical engineering , composite material , analytical chemistry (journal) , crystallography , chemistry , optics , organic chemistry , physics , catalysis , quantum mechanics , engineering
Different types of poly(ethylene terephthalate) (PET) films suffering a deformation process have been studied at the molecular level by different groups using FTIR spectroscopy in a rheo‐optical system. However, there is a clear lack of knowledge about the real‐time behaviour at a molecular level of the deformation process of bulk samples. The substitution of the FTIR system by the more recently developed FT‐Raman spectroscopy has allowed the study of such samples. Amorphous bulk PET samples were stretched at different temperatures below and above the glass transition temperature ( T g ) and three different mechanical behaviours were found with three corresponding behaviours at molecular levels. At temperatures below T g , there is a gauche to trans conformational transition in the C—C bond of the ethylene glycol fragment. At temperatures around T g this conformational transition is lost and no conformational changes were observed. At higher temperatures the gauche to trans transition is again present. The molecular behaviour was analysed in terms of the mobility of the chains, which suffered temperature‐instigated increases and decreases when thermal crystallization took place on the sample.