Three dimensional molecular orientation of isotactic polypropylene films under biaxial deformation at higher temperatures

We investigated the in-situ molecular orientation behavior of isotactic polypropylene (iPP) films under simultaneous and sequential biaxial deformation by polarized infrared spectroscopy at near melting temperature. The three-dimensional orientation functions in two stretching directions (in-plane o...

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Bibliographic Details
Published in:Polymer (Guilford) 2015-09, Vol.74, p.30-37
Main Authors: Nitta, Koh-hei, Sawada, Takayuki, Yoshida, Shingo, Kawamura, Takanobu
Format: Article
Language:English
Subjects:
Bands
Biaxial deformation
Deformation
Elongation
Isotactic
Isotactic polypropylene
Molecular orientation
Orientation
Polypropylenes
Stretching
Three dimensional
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Summary:We investigated the in-situ molecular orientation behavior of isotactic polypropylene (iPP) films under simultaneous and sequential biaxial deformation by polarized infrared spectroscopy at near melting temperature. The three-dimensional orientation functions in two stretching directions (in-plane of the film specimen) and its thickness directions were obtained from the dichroic ratios of two bands with different transition moments. Equi-biaxial stretching was found to cause iPP chains in both crystalline and amorphous regions to rotate towards the stretching plane. However, under sequential biaxial elongation, the iPP chains in both regions first oriented towards the first stretching direction and then rotated to the second stretching direction during the second stretching process. [Display omitted] •We proposed an experimental method for in-situ measurements of the molecular orientation of a polypropylene film under biaxial extensions.•We performed in-situ measurement of IR spectra under simultaneous and sequential biaxial stretching.•We estimated the three dimensional orientation functions of the polypropylene film during biaxial extension.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2015.07.049