Evaluation of Nanocomposites for Shielding Electromagnetic Interference

摘要

Numerous efforts are ongoing to research and develop nanocomposite materials for space applications. Current composite spacecraft materials are nonconductive and require costly shielding materials to be applied in order to protect spacecraft from the harmful effects caused by electromagnetic interference (EMI), which is a by-product of exposure to the space environment. Conductive fillers (nanofibers) are being employed in composites to produce nanocomposites to reduce the dry weight of space vehicles while providing sufficient protection against EMI. This eliminates the need to apply secondary shielding materials to spacecraft. This thesis studied a nanocomposite consisting of Cycom 5575-2 glass with multi-walled carbon nanotube (MWNT) plies. Four distinct configurations were tested for their EMI shielding effectiveness (SE) before and after thermal cycling and monotonic tension tests of increasing loads up to fracture. This study found that the EMI SE experienced minor reductions after thermal cycling and monotonic tensions tests, and failure mechanisms were consistent regardless of stacking sequence: transverse matrix cracks formed leading to delamination, which generated more matrix cracks and additional delamination resulting in ultimate failure. EMI SE measurements were performed post-fracture and demonstrated that the MWNTs remained intact and continued to provide sufficient EMI SE.