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Dynamic mechanical analysis of fibers. I. Effect of experimental variables and material type
Author(s) -
Khanna Y. P.,
Wenner W. M.,
Kumar R.,
Kavesh S.
Publication year - 1989
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.1989.070380316
Subject(s) - materials science , composite material , kevlar , dynamic mechanical analysis , ultimate tensile strength , modulus , young's modulus , dynamic modulus , tensile strain , fiber , annealing (glass) , polymer , epoxy
Depending upon the fiber material, some of the experimental variables can have a profound effect on the dynamic tensile modulus vs. temperature data. With the use of an experimental fiber (25°C < T g < 75°C; T m > 220°C; hot stretched), the effect of several variables, e.g., moisture/volatiles, annealing/relaxation, frequency (strain rate), pretension, and % strain on the modulus retention term [( E 100°C / E 25°C ) × 100] have been studied. Of these variables, pretension and especially % strain dramatically increase the modulus retention and this effect is attributed to the elastic orientation under force (EOF), i.e., it exists only in the presence of tensile forces and is reversible. Such an effect was insignificant for Kevlar ( T g − 375°C) and absent for steel wire. Dynamic modulus measurements at 25°C using sonic techniques also support the EOF phenomenon in polyethylene yarns ( T g ∼ −30°C) but not in Kevlar polymide yarns ( T g ∼ 375°C).