An electromagnetic wave absorbing material with self-healing function

With the development of communication technology, electromagnetic wave pollution is becoming more and more serious, reliable electromagnetic wave absorbing materials are needed. In this work, we modified the surface of hollow structure Fe 3 O 4 with amino group to obtain Fe 3 O 4 @SiO 2 -NH 2 , and then attached it to the molecular chain of self-healing polyurethane (PU) by chemical bonding to obtain PU-Fe 3 O 4 @SiO 2 -NH 2 . The sedimentation of nanoparticles in polyurethane solution can be effectively reduced by connection of chemical bonding between Fe 3 O 4 @SiO 2 -NH 2 and PU. 20 wt% Silver-plated carbon fiber (Ag@CF) conductive fillers were added into PU-Fe 3 O 4 @SiO 2 -NH 2 solution, self-healing electromagnetic wave absorbing material (Ag@CF/ PU-Fe 3 O 4 @SiO 2 -NH 2 ) was prepared finally. EDS mapping graphs showed that Fe 3 O 4 and Ag@CF nanoparticles were uniformly distributed in the PU matrix. When the content of Fe 3 O 4 @SiO 2 -NH 2 was 1.86 wt%, the tensile stress was 3.21 MPa, elongation at break was 574%, and the self-healing efficiency was 54% for Ag@CF/ PU-Fe 3 O 4 @SiO 2 -NH 2 . The minimum reflection loss (RL) was −71.6 dB with the thickness of 1.6 mm at 8.5 GHz, and the mechanism of absorbing microwave was analyzed. This shows that our material had good mechanical property, self-healing property and microwave absorbing performance.