Mechanical properties and energy absorption of semirigid PU/ER  interpenetrating polymer networks foams

A series of semirigid interpenetrating polymer networks (IPN) foams, based on polyurethane （PU） and epoxy resin（ER）, with different densities were prepared by a simultaneous polymerization technique. Compression and tension properties of these foams were measured. Over the range of densities examined, the compression moduli and yield stress of these IPN foams could be described by a power---law relationship with respect to density respectively. The tensile moduli and break strength of these foams were also found to exhibit the similar relationships with respect to density of the foams. Therefore, the change of mechanical properties along with the density of the foams could be well predicted using these models. Experimental results reveal that the IPN foams possess both better ductility and higher tensile strength, and the energy absorption in tension test is higher compared with that in compression test at the same strain.