COMPARISON BETWEEN NADIMIDE AND 1,2,3,6-TETRAHYDROPHTHAL-IMIDE END-CAPPED RESINS, PREPARATION AND THERMAL-BEHAVIOR

Nadimide and tetrahydrophthalimide end-capped oligomers have been synt hesized from a mixture of para- and meta-phenylenediamine, 4,4'-(hexaf luoroisopropylidene)diphthalic anhydride (HFDA) and nadic or tetrahydr ophthalic anhydride. Several percentages (25 to 50%) of metaphenylened iamine were used to obtain end-capped oligomers soluble in N-methylpyr rolidone. The tetrahydrophthalimide end-capped resins were characteriz ed by H-1 nuclear magnetic resonance and size exclusion chromatography ; their rheological behaviour was compared to their nadimide analogues . As expected from statistics both nadimide and tetrahydrophthalimide end-capped oligomers exhibit similar polydispersity ratios, with a hig h proportion of diimides which do not contain the HFDA moiety. However , their thermal treatments lead to different behaviours. Bis-nadimides gave crosslinked insoluble materials and bis-tetrahydrophthalimides g ave soluble materials in spite of the disappearance of their olefinic protons. (C) 1998 Elsevier Science Ltd. All rights reserved.