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Processing–property interactions in poly(vinylidene fluoride). II. Morphology and property characterization of extruded films
Author(s) -
Khomami B.,
McHugh A. J.
Publication year - 1988
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1988.070360411
Subject(s) - materials science , fourier transform infrared spectroscopy , crystallization , composite material , polarized light microscopy , differential scanning calorimetry , morphology (biology) , scanning electron microscope , optical microscope , phase (matter) , optics , chemical engineering , chemistry , thermodynamics , organic chemistry , physics , engineering , genetics , biology
The effects of flow history, processing temperature, and exit draw ratio have been studied for a poly(vinylidene fluoride) resin. Quantification of the stress fields and flow kinematics were described in Part I while, in this publication, attention has been addressed to the evaluation of film properties. Hot‐stage and differential scanning colorimetry (DSC) analyses were used to characterize the thermal behavior; polarized light optical microscopy and electron microscopy were used to characterize the morphology; Fourier transform infrared (FTIR) and wide‐angle x‐ray scattering (WAXS) were used to evaluate crystal structure; and mechanical testing was used to evaluate tensile properties. Extensional melt stresses on the order of 1.4 × 10 6 dyne/cm 2 were necessary to induce row‐nucleated crystallization in undrawn samples, and in all cases, preorientation of the melt by extensional flow enhanced the efficiency of the α → β transformation with drawing. The various transformations on drawing were as follows: unoriented α to oriented superheatable α phase for draw ratio (DR) < 5; transformation from α to β phase for 5 < DR ≤ 25; transformation to more highly oriented α and β phases, DR > 25.