High Strain Rate Mechanical Behavior of Polyurea As a Function of Stoichiometry

The stress-strain behavior of a commercial elastomeric polyuria prepared at three different stoichiometries (Air Products Versalink P1000 curative mixed with Dow Isonate 143L prepolymer, at weight mixing ratios 3.6:1, 4.0:1, and 4.4:1), in uniaxial tension was measured over range of strain rates from 0.08 to 500 s⁻¹. Increasing the mixing ratio decreased the stiffness and strength while increasing the elongation to failure. For blast protection, the relevant metric of performance is strain energy: the results were identical within scatter for the 3.6 and 4.0 rubbers, whereas the 4.4 rubber had comparatively inferior performance. There was a marked sensitivity of the stiffness, strength, and elongation to mixing ratio, but the strain energy was somewhat less sensitive to this characteristic.