Thermosetting polyester foams by infiltration in soluble preforms

Rigid thermosetting foams are produced by infiltration of an unsaturated polyester resin into a soluble preform. In the experimentation, preforms were made of carbamide particles which were compacted at different values of pressure to change the foam structure and properties. After resin polymerization, carbamide particles are evacuated by immersion in water, leaving pores into the samples. Foams with porosity ranging from 52% to 77% were obtained as a function of the preform density. Quasi-static and cyclic compression tests were performed to evaluate foam properties. By increasing porosity, the foam strength reduces as well as the energy adsorbed at failure, and the energy lost in each single loading–unloading cycle