Load sharing and accumulated bond fracture in ion-irradiated carbon mat for energy dissipation.

Multiwalled carbon nanotube (MWNT) aerogel mats were irradiated with carbon ions to explore the effect of irradiation-induced sp bonds and sp bond defects on ultrahigh strain rate mechanical properties. Energy dissipation was measured using a microprojectile impact test. Specific penetration energy [Formula: see text] increased strongly with irradiation with a maximum [Formula: see text] of ~26 megajoules per kilogram, over 200% higher than the previous best energy-absorbing material of pristine MWNT mats and at least an order of magnitude higher than any other material tested at the microscale. Perforation morphologies observed by electron microscopy show that a much larger network region is deformed due to sp bond enhanced load sharing within and between tubes, while defects introduced by the radiation induce more bond, shell, and tube damage leading to strongly enhanced energy dissipation.