Strain rate and temperature effects on impact properties of toughened epoxy resins

To investigate the effects of strain rate, temperature and toughening modification on the impact properties of epoxy resin, uniaxial dynamic compression tests are performed on neat and toughened epoxy resins at −40, 0, 23 ℃ (room temperature) and 70 ℃ using a split Hopkinson pressure bar (SHPB). The results show that both the neat and toughened epoxy resins exhibit significant strain-rate and temperature effects. At room temperature, toughening can effectively improve the energy absorption capacity of epoxy resin; however, the toughness decreases obviously when the temperature rises to 70  ℃ or drops to −40 ℃. At −40, 0 ℃ and 70 ℃, the toughness of the toughened epoxy resin deteriorates rapidly with increasing strain rate, even falling below that of the neat epoxy resin. Studies indicate that the enhancement of epoxy resin impact performance via toughening modification is only effective at ambient temperature. Under extreme high/low temperature environments and high-strain-rate loading, the toughening effect degrades drastically, which restricts the application of modified epoxy resins in service conditions featuring wide temperature ranges and dynamic loads.