Influence of MWCNTs and nano-Fe3O4 on the properties and structure of MWCNTs/ Fe3O4/PLA composite film with electromagnetic interference shielding function

A large number of electronic devices could generate a lot of electromagnetic waves, which could interfere with other equipment and harm the human body. Therefore, an electromagnetic interference shielding (EMI) material is urgently needed to protect the human body and the electronic equipment. In this paper, the multi-wall carbon nanotubes (MWCNTs) and the nano-Fe3O4 were added into the polylactic acid (PLA) matrix to form the composite film with electromagnetic interference shielding performance. And the structure and properties of MWCNTs/Fe3O4/PLA composite films, such as the morphology, chemical structure, crystallization, mechanical property, conductive property, magnetic property and electromagnetic interference shielding property, were researched. The result shows that too much Fe3O4 could lead to agglomeration, and the coupling agent KH570 had grafted and modified the surface of MWCNTs. The MWCNTs and nano-Fe3O4 could increase the crystallinity of PLA matrix. With the increase of MWCNTs, the maximum tensile stress of composite films gradually increased, and the maximum tensile strain decreased, and the resistance value showed a significant downward trend. The Fe3O4 could improve the magnetic properties of composite film. The MWCNTs and Fe3O4 could improve the electromagnetic interference shielding efficiency (EMI SE). The MWCNTs played a more significant role than the Fe3O4 in the process of EMI, and the EMI SE of the composite film with 3:1 ratios of MWCNTs/Fe3O4 could rise to 22 dB.