Interpenetrating polymer networks formed by cyanate esters and phenylethynyl-terminated imides

An oligomeric phenylethynyl-terminated imide (PETI) has been formulated with a cyanate ester (CE) with and without the addition of a compatibilizer 2,2-diallylbisphenol A (DABPA) forming interpenetrating polymer networks (IPNs). Modulated differential scanning calorimetry (mDSC) was used to monitor the curing of the resin mixtures. The formation of various resulting IPNs was verified using mDSC, dynamical mechanical thermoanalysis (DMTA), thermal gravimetry analysis and scanning electron microscopy. Furthermore, it could be shown by mDSC and DMTA that a covalent bond of the separated CE and PETI networks could be achieved by the addition of DABPA. In this regard, a reaction mechanism is proposed for the cross-linking reaction between the allylic pendent group of DABPA and the phenylethynyl end-group of the PETI resin. The cured resin specimens showed to have very high heat resistance and very high glass transition temperatures up to 330 degrees C.