End Caps Increase Thermo-Oxidative Stability of Polyimides

Latently reactive end caps have been investigated as improved means to increase the thermo-oxidative stability of polyimides of the polymerization of monomeric reactants (PMR) type, which are often used as the matrix resins of high-temperature-resistant composite materials. The present end-cap compounds are candidates to supplant the norbornene end cap (NE) compound that, heretofore, has served to limit molecular weights during oligomerization and, at high temperatures, to form crosslinks that become parts of stable network molecular structures.