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Comparative analysis of structure and temperature behaviour of two copolyamides ‐ regular KEVLAR and statistical ARMOS
Author(s) -
Levchenko Andrei A.,
Antipov Evgueni M.,
Plate' Nikolaj A.,
Stamm Manfred
Publication year - 1999
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19991460120
Subject(s) - mesophase , materials science , crystallinity , polymer , glass transition , phase transition , polymer chemistry , liquid crystal , hydrogen bond , phase (matter) , relaxation (psychology) , composite material , crystallography , chemical engineering , polymer science , thermodynamics , chemistry , organic chemistry , molecule , physics , psychology , social psychology , optoelectronics , engineering
In the present investigation X‐ray diffraction techniques, DSC and dynamic mechanical relaxation (DMR) methods have been employed to compare the structure and thermal behaviour of Kevlar (“DuPont”, USA) and Armos (Russia) fibers. Our recent studies have indicated that the non‐crystalline phase of copolyesters always contains LC smectic structure in addition to some part of the nematic LC mesophase. It turned out that the copolyamides also possess this interesting feature. Moreover, on heating of a semicrystalline copolyester always the second order phase transition from the crystalline state to condis mesophase has been observed, whereas in the case of copolyamides such a transition has the «virtual» character. As was established by other authors both polymers under study reveal the moisture content. The changes in wide angle X‐ray scattering of copolyamides under heat treatment were interpreted in terms of desorption of bound water and structural rearrangement in the plane perpendicular to the chain axis involving of the hydrogen bonding between neighboring macromolecules.