Nanotoughening and microtoughening of polymer syntactic foams

The strategies of toughening polymer foams, particularly rigid polymer syntactic foams, are discussed. The discussion begins with a general introduction of toughness and the toughening mechanism in brittle polymer systems before focusing on two of the very successful and effective toughening strategies of thermoset/hollow sphere syntactic foams using microfibers and nanoparticles. Finally, the possible mechanisms for the substantial toughening effect using even a small amount of micro- or nanoparticles in the syntactic foams are proposed and analyzed. It is believed that such an in-depth understanding should enable the formulation of suitable toughening methods for different polymer foam systems.