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Morphological effects of ballistic impact on fabrics of highly drawn polyethylene fibers
Author(s) -
Desper C. Richard,
Cohen Samuel H.,
King Abram O.
Publication year - 1993
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.1993.070470701
Subject(s) - monoclinic crystal system , polyethylene , materials science , orthorhombic crystal system , crystallinity , composite material , recrystallization (geology) , melting point , diffraction , crystallography , phase (matter) , crystal structure , chemistry , organic chemistry , optics , geology , paleontology , physics
Changes in crystalline structure of high‐tenacity ultra‐high‐molecular‐weight polyethylene fabric brought on by ballistic impact from a small projectile were determined by X‐ray diffractometry. A suitable X‐ray diffraction method that averages out the fiber orientation effects in the diffraction pattern was used. The Spectra 1000™ polyethylene fabrics were successfully characterized in terms of both the predominant orthorhombic and the minor monoclinic crystal content. Crystallinity values for the undamaged fabric are consistent from sample to sample and show an average orthorhombic fraction of 0.61 and an average monoclinic fraction of 0.04. Fabric damage by the projectile impact results in either an increase in monoclinic fraction, attributed to recrystallization at temperatures nearing the normal polyethylene melting point, or disappearance of monoclinic material as that temperature is exceeded. The latter predominates where ballistic penetration is complete. However, actual melting need not be involved: Transformation to the hexagonal (“rotator”) phase and the disappearance of the monoclinic phase could have occurred rather than true melting. © 1993 John Wiley & Sons, Inc.