DYCOMP - ECCCS – 3 2024

Polyurea-based coatings with Multiwall Carbon Nanotubes: A dynamic regime study

  • Dîrloman, Florin-Marian (Military Technical Academy "Ferdinand I")
  • Toader, Gabriela (Military Technical Academy "Ferdinand I")
  • Diacon, Aurel (Military Technical Academy "Ferdinand I")
  • Rotariu, Adrian (Military Technical Academy "Ferdinand I")

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This study frameworks a dynamic regime approach for characterizing a new, simple, practical, inexpensive, improved, and effective method for obtaining carbon nanotube-reinforced polyurea-based formulations. These formulations are designed to form coatings that provide superior ballistic protection by enhancing their response to shock waves and shrapnel action on the structures to which they are applied. The optimal formulation involves mixing two commercial prepolymers (Component A, which is an amine and polyol mixture, with Component B, an isocyanate-based prepolymer). Modified nanotubes are then added to Component A at a concentration of 0.2% of the total reaction mixture. For experimental testing in the dynamic regime, a Hopkinson bar set-up was used, with each specimen clamped and aligned for axial symmetry. An air gun, which allows the pressure to vary, launches the impactor (the projectile with a spherical head in our case) towards the centre of the test specimen. Upon impact, the specimen is promptly subjected to the compressive stress wave, resulting in rapid and permanent plate deformation or fracture (see Figure 1). The aluminum plate cracks at 1 bar pressure when the projectile is 20 cm away. In two-layer configurations, both materials reduce damage to the plate, with the polyurea layer absorbing the projectile's energy and minimizing deformation. Similar deformation was observed under the following conditions: - 1 and 1.5 bar pressure at 20 and 40 cm resulted in cracks or complete perforation of aluminum plates without polyurea. - 1 and 1.5 bar pressure at 20 and 40 cm caused cracks in the aluminum plate and released the polyurea in double-layered plates with simple polyurea and polyurea with nanotubes (see Figure 1). The additional material incorporated into the two compositions presents a favorable impact on enhancing the strength of the original aluminum plate. These materials hold potential for application in retrofit solutions for individual or collective ballistic protection, particularly aimed at reducing the metal mass of military vehicles or bulletproof vests. This initiative could yield substantial advancements in the weight of military equipment.