Multifunctional polyetherimide nanocomposite foam

Abstract

Polyetherimide/multi-wall carbon nanotube nanocomposite foams were fabricated and their electrical and mechanical properties characterized. The composites with 0.5–3 wt% of carbon nanotube loadings were fabricated using a solution-based method. Different foaming conditions were studied along with the residual solvent effects. It was found that the residual solvent significantly affected the mechanical properties of the nanocompsites. Electrical conductivity of the composite foams with the same wt% loading of carbon nanotubes was found to be dependent on the relative density of the foams. Foams with a higher relative density had a higher electrical conductivity. The fabricated polyetherimide nanocomposite foam is thermally stable, with a glass transition temperature close to that of the neat polyetherimide. Despite the volume expansion due to foaming, the polyetherimide nanocomposite foams achieved an electrical conductivity of 10−7 S/cm at 2 wt% carbon nanotube loading and 45% relative density. This makes them a multifunctional material for lightweight and electrostatic dissipative applications.

Conductive polymer foams with carbon nanofillers – Modeling percolation behavior

“…Specifically, the incorporation of pores in nanocomposites was responsible for a more dense filler network, with shorter path for electron transport, less electron scattering, and thus increased conductivity and reduced percolation threshold [23]. Kim et al reported experimental studies of polymer foams incorporating CNTs [24,25]. The authors observed an increase in electrical conductivity and decrease in percolation threshold with porosity when considering a fixed filler amount.…”

“…Similar experimental observations and interpretations have been reported by Tran and coworkers [27,28] and Zhi et al [29] for porous nanocomposites incorporating multiwalled CNTs. Some processing techniques using high aspect ratio fillers, including CNTs [25] and GNPs [30], can result in a morphology characterized by highly oriented fillers. Experimental observations have shown that electrical conductivity depends on filler alignment in solid nanocomposites.…”

How much do nanoparticle fillers improve the modulus and strength of polymer foams?

“…It is also possible to guarantee samples of exactly the same density by foaming in a closed mold, thus limiting the expansion to a pre-specified value. 29–31 Even in such cases, however, a density gradient between the core and the walls 32–36 may provide misleading results. In extreme cases, the formation of a skin at the surface may significantly affect mechanical measurements, especially if the foam density is very low.…”

Preparation and characterization of poly(ether imide) nanocomposites and nanocomposite foams

“…High-performance polymer matrices could be used, such that the resultant nanocomposite foams could be employed in a more stringent environment where high-service temperatures are required. Kim and Li (2013) fabricated PEI/MWCNT nanocomposite foams and characterized their electrical and mechanical properties. PES is an amorphous polymer having a glass transition temperature (T g ) of 225 °C and a density of 1.37 g/cm 3 .…”