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Uniplanar orientation of poly( p ‐phenylene terephthalamide) crystal in thin film and its effect on mechanical properties
Author(s) -
Haraguchi Kazutoshi,
Kajiyama Tisato,
Takayanagi Motowo
Publication year - 1979
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.1979.070230325
Subject(s) - materials science , poly(p phenylene) , crystal (programming language) , crystal structure , composite material , anisotropy , thin film , crystallography , polymer , optics , nanotechnology , chemistry , physics , computer science , programming language
The uniplanar orientation of poly( p ‐phenylene terephthalamide) (PPTA) crystal was investigated by x‐ray and infrared measurements. Thin PPTA films 3–15 μm thick were prepared by coagulating a sulfuric acid solution of PPTA with various coagulants. Two types of uniplanar orientation were observed, depending on the coagulant used. Thin film coagulated with water exhibits (0 k 0) uniplanar orientation and film coagulated with other coagulants such as methanol, ethanol, and acetone exhibits ( h 00) uniplanar orientation. These ( h 00) and (0 k 0) uniplanar orientations are formed with crystal modifications I and II, respectively. The (0 k 0) uniplanar orientation transforms to ( h 00) upon annealing, accompanying crystal transformation from modification II to modifications I. These uniplanar orientations may result from anisotropic crystal growth due to polymer–coagulant interaction along the hydrogen bond direction. The effect of these uniplanar orientations on the mechanical properties was also examined. The thin film having the (0 k 0) uniplanar orientation shows ductile fracture, whereas the one having the ( h 00) uniplanar orientation shows brittle fracture upon tensile deformation. These results are explained on the basis of the direction of the uniplanar orientation of the hydrogen‐bonded sheet.