Mitigating the effects of space debris on composite structures embedding self healing and carbon nanotube nanocomposite materials

The presence in space of micrometeoroids and orbital debris, particularly in the lower earth orbit, presents a continuous hazard to orbiting satellites, spacecrafts and the international space station. Space debris includes all non-functional, man-made objects and fragments. As the population of debris continues to grow, the probability of collisions that could lead to potential damage will consequently increase. We report on our recent results obtained on the application of self healing composite materials on impacted composite structures used in space. Self healing materials were blends of microcapsules containing mainly various combinations of a 5- Ethylidene-2- Norbornene (5E2N) and dicyclopentadiene (DCPD) monomers, reacted with ruthenium Grubbs\u92 catalyst. The self healing materials were then mixed with a resin epoxy and single-walled carbon nanotubes (SWNTs) using vacuum centrifuging technique. The obtained nanocomposites were infused into the layers of woven carbon fibers reinforced polymer (CFRP). The CFRP specimens were then subjected to hypervelocity impact conditions by using an advanced implosion driven-hypervelocity launcher - to simulate the space debris impact- with projectiles of about 4 mm in diameter and velocities up to 9 km/s. Although the microencapsulated self healing materials would not heal the impact's crater zone, we focused mainly on the reparation of potential delaminations developed around the impact-crater over distances much larger than the crater diameter. The different self-healing capabilities were determined and the SWNTs contribution was discussed with respect to the experimental parameters