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Formation and characterization of cast and biaxially stretched poly(butylene terephthalate) film
Author(s) -
Song Kwangjin,
White James L.
Publication year - 1998
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.10213
Subject(s) - materials science , crystallinity , crystallite , annealing (glass) , composite material , transverse plane , polymer , crystallography , metallurgy , structural engineering , chemistry , engineering
An experimental study of structure development in cast film exhibited only α‐form crystallites and relatively low crystallinities ( X c = 3.5–14%), while biaxially stretched films showed a mixed character of both α‐ and β‐form crystallites with crystallinities of 20–30%. Crystal perfection increases with uniaxial deformation. Biaxiality causes a decrease both in crystal perfection and crystallinity of the films. Annealing increases crystallinity. The orientation of the films has been determined by refractive indices and WAXS pole figures. Polymer chains orient rapidly to the machine direction (MD) with uniaxial stretching. Increasing biaxiality causes an increase in population of TD‐oriented crystals. The planarity of the film increases with simultaneous transverse stretching. The phenyl rings orient into the plane of the film. Annealing further increased the orientation of the films.