High tear strength polyurea foams with low compression set and shrinkage properties at elevated temperatures

Abstract

The mechanical properties of low-density polyurea (PU) foams (150–300 kg/m3) are presented. The hardness, tensile strength, elongation, compression set, resilience, tear strength, and shrinkage were investigated according to the American Society for Testing and Materials (ASTM) test method D3574-08. The polyurea foams were then compared with widely used thermoplastic polyurethane (TPU) foam technologies at similar densities. PU foams displayed similar values of tensile strength (0.4–1.5 MPa) and resiliency (37–41%) as TPU foams across all densities (150–300 kg/m3). However, on average, PU foams exhibited a 3% increase in elongation, 27% increase in tear strength, 130% decrease in compression set values, and 289% decrease in dry heat shrinkage values at a minimal 6% increase in hardness over TPU samples. Thus, PU foams show greater tear resistance, durability, and elasticity over TPU foams, even at prolonged periods of compression and temperature. These properties should allow these materials to have a wide range of cushioning/impact applications, especially in athletic footwear and protective body/headgear systems.