ISSN:
0959-8103
Keywords:
telechelic polyimides
;
nadimide
;
endo/exo isomerization
;
NMR
;
HPLC
;
thermomechanical properties
;
α and β transitions
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
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 (1H and 13C), 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 Tg) 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 M̄n 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 Tg increased by 50°C.
Additional Material:
20 Ill.
Type of Medium:
Electronic Resource
