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Dynamic mechanical and broad line nuclear magnetic resonance behavior of some aromatic polyamides
Author(s) -
Frosini V.,
Levita G.,
Butta E.
Publication year - 1979
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760190110
Subject(s) - polyamide , materials science , polymer , relaxation (psychology) , intramolecular force , phase (matter) , benzene , aramid , nuclear magnetic resonance , polymer chemistry , chemical physics , composite material , organic chemistry , chemistry , physics , psychology , social psychology , fiber
The results of dynamic mechanical and broad‐line proton magnetic resonance studies carried out over a broad, temperature range on a series of aromatic polyamides are presented. At temperatures lower than 300 K, the NMR data show no relaxation for the all‐meta linked benzene rings polyamide, whereas processes for the other polyamides are found, the magnitude of which is dependent on the polymer structure. Between 400 and 500 K further decreases in the second moment take place for all materials. Two secondary mechanical loss peaks are evident in these polymers, one in the 200‐380 K region (β) and one in the 380‐500 K region (β * ), at about 10 4 cps. In particular, the relaxation strength of the β * peak depends on the conditions of isolation of the polymers from solution. The results are discussed in terms of possible motional processes of these polymers characterized by a long range intramolecular uniaxial order. An attempt is made to correlate the relaxational properties of aromatic polyamides to the existence of a phase of low regularity such as the nematic or smectic mesophases.