Enhancing the electrical conductivity of polyetherimide‐based foams by simultaneously increasing the porosity and graphene nanoplatelets dispersion

Significant improvement in electrical conductivity of graphene nanoplatelets‐filled polyetherimide (PEI) foams was achieved by simultaneously increasing the porosity and graphene nanoplatelets dispersion. Foams were prepared by means of water vapor‐induced phase separation using a concentration of graphene nanoplatelets (GnP) between 1 and 10 wt%. To obtain two sets of foams having different density and porosity, PEI's concentration in N‐methyl pyrrolidone (NMP) solvent prior to foaming was set at 15 and 25–30 wt%, respectively. High‐power sonication was applied to GnP‐NMP suspension before PEI's addition for the foam series with higher porosity (15 wt% PEI). All foams were later characterized in terms of cellular structure, thermal stability, dynamic‐mechanical properties, and electrical conductivity. A notable enhancement in electrical conductivity was observed with foaming, especially when increasing the porosity and applying sonication, with foams reaching values as high as 1.7 × 10⁻¹ S/m while maintaining the thermal stability and mechanical performance. POLYM. COMPOS., 40:E1416–E1425, 2019. © 2018 Society of Plastics Engineers