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New thermostable systems: structure/property relationships of nadic terminated telechelic fluorine polyimides
Author(s) -
GrenierLoustalot M. F.,
Billon L.
Publication year - 1996
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199610)41:2<135::aid-pi603>3.0.co;2-o
Subject(s) - glass transition , phthalic anhydride , materials science , condensation polymer , polymer chemistry , dynamic mechanical analysis , molar mass , diamine , polymer , polymerization , rheology , organic chemistry , composite material , chemistry , catalysis
Polyimides were synthesized by polycondensation of nadic anhydride monoester (NE), hexafluoroisopropylidene‐2,2‐bis (phthalic acid anhydride) (6HFDA) and Cardo diamine in aprotic/polar medium. After examining the microstructure and the composition of systems with a polymerization index n̄ = 2.075 and 5.18 by high performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) spectroscopy ( 1 H and 13 C), their thermomechanical properties were investigated. The rheology curves obtained in the temperature range 50–400°C showed the presence of an α transition (glass transition temperature T g ) and a sub‐glass β transition. The temperature of the maximum of the loss modulus G ″ of these two transitions varied in the domain of molar mass M̄ n studied. The effect of endo/exo isomerization of the nadimide extremities on the values of the glass transition temperature has also been shown. When the percentage of exo isomer of a given polymer increased, the glass transition temperature T g increased by 50°C.