Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range Articles uri icon

publication date

  • April 2016

start page

  • 10724

end page

  • 10730

issue

  • 20

volume

  • 8

International Standard Serial Number (ISSN)

  • 2040-3364

Electronic International Standard Serial Number (EISSN)

  • 2040-3372

abstract

  • Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at −20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100&-150 mum) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials.

keywords

  • shielding effectiveness; polymer composites; epoxy composites; performance; permittivity; oxidation; catalyst