Mechanical behavior and failure mechanism of polyurea nanocomposites under quasi-static and dynamic compressive loading

Polyurea for Blast and Impact Protection: A Review

“…The mechanical properties of polyurea can be tuned by choosing different variations of diamines and diisocyanates as well as by adding assorted nano-inclusions and micro-inclusions to create polyurea-based composites [5,66,67]. Nano-inclusions and micro-inclusions dispersed in the matrix can also improve the interfacial strength of the material, resulting in some enhancement [68]. The integration of high stiffness and high damping materials (e.g., polyurea) into one material system appears to be somewhat contradictory in the material design.…”

“…Adding an appropriate amount of reinforcing material enables the polyurea to crack inside the coating and to deflect the cracks during the damage process, increasing the absorption of the fracture energy. A large amount of crazescan also prevents crack expansion, reduces crack generation and improves the toughness of the composite [68]. The enhancement of the strength and stiffness of the composite depends, to a large extent, on the quality of the interfacial bond between the reinforcement and the matrix [3].…”

“…Due to a mismatch between the mechanical properties of the materials, delamination between the reinforcement and the substrate often occurs at the interface or in the interphase region due to stress build-up. Large amounts of nano-reinforced and micron-reinforced materials can easily reduce the dispersion and lead to a stress concentration effect that can negatively affect the mechanical properties of polyurea [22,43,[68][69][70].…”

“…Both Liu [40] and Iqbal et al [54] considered that In addition, researchers have recently found that adding reinforcing materials to polyurea increases the strain rate sensitivity of polyurea. Liu et al [68] revealed that the flow stress and compressive strength increased by 12.8% and 12.1%, respectively, under a strain rate of 8000 s −1 load compared to unreinforced polyurea with the SiC-reinforced polyurea.…”

“…The process of energy dissipation is accompanied by an increase in temperature, which in turn affects the mechanical response [19,46,94]. Liu et al [68] found that impact energy acting on polyurea is transformed into thermal energy under a high strain rate impact, resulting in thermal softening and stress reduction. Mott et al [19] employed high-speed thermography to measure transient temperature changes in the deformed polyurea, and they found that the unusual viscoelasticity degree is due to a high Tg and large internal friction.…”