Effect of urea derivatives on the volume shrinkage during curing of cyanate ester and epoxy resins with polymeric hardener based on phenol-amine salt

Effect of urea derivatives (UDs) on volume shrinkage during the curing of bisphenol A diglycidyl ether (BAGE)/bisphenol E cyanate ester (DCBE)/thermal latent polymeric hardener based on phenol-amine salt (PAH) was investigated. The UDs with N-H bonds and bulky substituents reduced the volume shrinkage effectively. The UDs were just dispersed in the compositions before the curing, whereas the UDs dissolved in the cured compounds by the collapse of the dense packing of UDs based on hydrogen-bonding interaction and/or p-stacking after the curing. Besides, the curing behavior and the structure of cured materials were examined by DSC and IR. The results revealed that the UDs hardly affected the curing of the DCBE/BAGE/PAH system.