Elastomeric coatings have gained significant attention as retrofit materials for specific applications, particularly in blast mitigation and ballistic protection. One such elastomer is polyurea, which is produced by the reaction of isocyanate and amine. This unique material is characterized by the presence of hard domains dispersed randomly within the soft areas, creating a mosaic landscape with a nano-segregated microstructure. Each field within the material exhibits its own characteristic glass transition temperature.
Polyurea made its entry into the commercial market in the late nineteen-eighties and has since gained immense recognition due to its exceptional blast mitigation properties and ballistic stability. Numerous studies have highlighted the potential of polyurea for retrofitting applications, emphasizing its remarkable properties. However, the underlying mechanism responsible for these exceptional properties is not yet fully understood.
The ballistic protection capability of polyurea is closely associated with its ability to undergo a dynamic transition from a rubber-like state to a glass-like state. This transition occurs when the material is subjected to extremely high strain levels. On the other hand, the blast mitigation potential of polyurea is attributed to a phenomenon known as shock wave acquisition and neutralization. This phenomenon allows the material to effectively absorb and dissipate the energy from an explosion or impact.
Optimizing the composition and structure of polyurea is key to maximizing its blast mitigation and ballistic protection abilities. The presence of hard and soft domains within polyurea is crucial for its respective properties. Therefore, careful selection of the raw materials and manufacturing processes is essential for tuning the polymer to meet the specific requirements of critical applications.
The scope of this article is to review the existing publications in the field of polyurea-based retrofits. It will cover topics such as the preparation methods for polyurea, characterization techniques to assess its properties, and various applications in the context of blast mitigation and ballistic protection. By analyzing the current knowledge and research in this area, this article aims to provide a comprehensive understanding of polyurea’s potential as a retrofit material for strategic purposes.
