10 - The Interaction of High Strain-Rate Elastomeric Polymer Coating with the Substrate Material and the Mechanisms of Failure

Abstract

Following the discovery that polyurea (a high strain rate elastomeric polymer, HSREP) could prevent the rupture of thick high strength steel plates when subjected to detonated close-in and contact underwater explosive charges, high strain rate sensitivity was identified as the basic mechanical property of these polymers that makes them unique for blast applications. The blast-resistant properties of these polymers, namely high rate sensitivity, is not the only property that makes them unique for the applications discussed in this book, but also how they interact with the underlying substrates/materials, which is quite different from any blast or ballistic material known to the shock community. It should be emphasized that, even though HSREPs have unique properties of their own, they are not used alone as other blast or ballistic materials are; HSREPs are always used with other materials. Blast protection has become an important problem in many military and civilian structures. In this regard, a rather interesting phenomenon has been observed experimentally – coating metallic structural components with a layer of a compliant polymer, typically an elastomer with a glass transition temperature significantly below the use temperature, decreases the propensity of the metallic structure to fracture and fragment. This observation has spawned a large number of research efforts aimed at understanding and optimizing the additional impact resistance provided by such polymer-coated metal structures.