A series of porous epoxy foams toughened by liquid natural rubber (LNR) were fabricated by sodium bicarbonate (SB) as chemical foaming agent and finding the optimal composition ensuring both high porosity and mechanical strength. In this research, we studied the properties of epoxy foam by adding LNR as toughening agent in contents of (5 to 25 vol%) with adding 15 phr of SB as an optimal content foaming agent. The flexural, fracture toughness, compression, cross-link density, morphology and thermal stability properties of epoxy foam was characterized. Cellular plastics keep mechanical strength loss and plastic weight to a minimum through cells inside the foam. Increasing the content of LNR retarded the crosslinking reaction by increasing the expansion and affected the mechanical strength. A suitable expansion and mechanical strength were observed for epoxy-foam containing 10 to 15 vol% LNR. Densities of the foams can be tuned in a range of up to 0.760 g/cm3 by changing the content of LNR from 5 to 25vol%. The compressive strength was decreased from 8.62 and 4.15 MPa.
