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Study of the molecular structure of PET films obtained by an inverse stretching process. Part I: Constant speed drawing of amorphous films
Author(s) -
Vigny M.,
Tassin J. F.,
Gibaud A.,
Lorentz G.
Publication year - 1997
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11827
Subject(s) - materials science , amorphous solid , composite material , relaxation (psychology) , viscosity , inverse , diffraction , deformation (meteorology) , constant (computer programming) , stress relaxation , polymer , optics , crystallography , creep , geometry , social psychology , programming language , chemistry , mathematics , physics , computer science , psychology
The constant rate stretching of amorphous poly(ethylene terephthalate) films is the first step of the industrial “inverse” process. To study this process, films deformed under uniaxial planar symmetry conditions have been produced on a laboratory stretching machine in order to discuss the influence of macroscopic parameters, such as draw ratio, temperature and melt viscosity of the amorphous film, on the deformation mechanism. The structure of oriented films has been characterized by combining X‐ray diffraction and refractive index measurements. Stress strain curves have been simultaneously recorded. The draw temperature and the molecular weight of the polymer are determining factors controlling the development of molecular orientation and crystalline structure in the stretched films. The major influence of relaxation processes is described and a comparison with constant force drawn films is given.