Fourier transform infrared spectroscopic characterization of aromatic bismaleimide resin cure states

Interesting polyimide materials, possessing good mechanical and thermal properties, are obtained by homopolymerization or reaction of 4,′4‐bis(maleimidodiphenylmethane) with a diamine. Fourier transform infrared spectroscopy has been used to characterize the crosslinking of such materials using maleimide and amine absorption bands. Amine group reaction on double bonds is readily achieved and appears to be insensitive to the temperature of curing. On the other hand, the decrease of maleimide double bonds is strongly dependent on the reaction temperature. The residual amount of double bonds present in the cured material is a function of the temperature: a linear relationship holds between residual double bond concentration vs. curing temperature. The general behavior during crosslinking of this kind of polyimide was related to glass transition temperature changes.