In order to characterize the various residual fragments or those created during the use and polymerization of bismaleimide prepolymers, different compounds characteristic of the expected fragments were synthesized and physicochemically characterized by Fourier-transform infra-red spectroscopy, nuclear magnetic resonance spectroscopy and differential scanning calorimetry. Thus, depending on heating temperature, the bismaleimide telechelic group gives rise to chain extension at 140-150-degrees-C in the presence of aromatic diamines, either by addition or by maleimide ring opening. At higher temperatures (200-degrees-C) it causes a crosslinking reaction, which forms a three-dimensional system.