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Thermally crosslinked rigid‐rod aramids, 2. Fiber spinning and fiber properties
Author(s) -
Glomm Bernhard,
Rickert Christoph,
Neuenschwander Peter,
Suter Ulrich W.
Publication year - 1994
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1994.021950211
Subject(s) - crystallinity , aramid , spinning , materials science , diamine , annealing (glass) , composite material , polymer chemistry , synthetic fiber , radical , fiber , copolymer , polymer , chemistry , organic chemistry
Fibers of three rigid‐rod aromatic copolymers, produced by polycondensation of 2,2,6,6‐tetraoxo‐1,3,5,7‐tetrahydro‐2,6‐dithia‐ s ‐indacene‐4,8‐diamine (DSDA), p ‐phenylenediamine and terephthaloyl dichloride, were spun from nematic solutions and characterized by wideangle X‐ray‐diffraction (WAXD) measurements and mechanical tests. A post‐spin heat treatment was employed to improve the low degrees of orientation and crystallinity exhibited generally by the untreated fibers. The dominating crystal structures of the copolymers are similar to “modification I” of the well known fibers from poly( p ‐phenyleneterephthalamide) (PPTA). Thermally induced crosslinking of the fibers in the solid state was performed simultaneously with post‐spin treatment. The influence of the annealing conditions on the mechanical fiber properties and the molecular order in the fibers was also investigated. All mechanical parameters were time‐dependent, probably due to the generation of stable radicals during heat treatment. The radicals may give rise to chain scission.