Epoxy composite foams with excellent electromagnetic interference shielding and heat-resistance performance

Epoxy composite foams with improved heat-resistant property and efficient electromagnetic interference shielding effectiveness (EMI SE) were fabricated through a two-step foaming technique. A sort of novel and untraditional expandable microspheres was adopted to reduce the density of prepared materials. A multiscale conductive network system composed of multiwalled carbon nanotubes (MWCNTs) and nickel-plated carbon fibers (NiCFs) was introduced in these foams. Benefitting from the synergistic effect between NiCFs and MWCNTs, the multiscale epoxy foam with best comprehensive performance achieved a greatly enhanced T-g at 178.3 degrees C and an exceptional specific EMI SE ranging from 52.8 to 72.6 dBcm(3)g(-1) in X band (8.2-12.4 GHz) at low filler loading. These properties are greatly better than original epoxy foam with a T-g of 157.8 degrees C and specific EMI SE of 1.0-6.4 dBcm(3)g(-1). Their shielding mechanisms were discussed and the results showed that reflection is dominating. The effects of microspheres content, foaming temperature, NiCFs content, and length were investigated. In general, we provided a feasible, convenient and cost-effective method to fabricate light-weight, heat-resistant thermosetting epoxy foams with sufficient EMI shielding performance which has a potential to be applied in aerospace or electronic devices. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46013.