Batch foaming of carboxylated multiwalled carbon nanotube/poly(ether imide) nanocomposites: The influence of the carbon nanotube aspect ratio on the cellular morphology

A series of microcellular poly(ether imide) (PEI) foams and nanocellular carboxylated multiwalled carbon nanotube (MWCNT‐COOH)/PEI foams were prepared by the batch foaming method. MWCNT‐COOHs with different aspect ratios were introduced into the PEI matrix as heterogeneous nucleation agents to improve the cell morphology of the microcellular PEI foams. The effect of the aspect ratio of the MWCNT‐COOHs on the cellular morphology, and gas diffusion is discussed. The results show that with the addition of MWCNT‐COOH, the sorption curve showed a slight reduction of carbon dioxide solubility, but the gas diffusion rate could be improved. The proper aspect ratio of MWCNT‐COOH could improve the cellular morphology under the same foaming conditions, in which m‐MWCNT‐COOH (aspect ratio ≈ 1333) was the best heterogeneous nucleation agent. When the foaming temperature was 170°C, the cell size and cell density of nanocellular m‐MWCNT‐COOH reduced to 180 nm and increased to 1.58 × 10¹³ cells/cm³, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42325.