Mechanically whipped phenolic froths as versatile templates for manufacturing phenolic and carbon foams

Abstract

Stable, liquid phenolic froths have been produced by whipping air into a mixture of phenolic resole, catalyst and surfactant. These liquid froths can be moulded into desired shapes and cured to produce open porous phenolic foams. This method, which we call froth templating, has been scaled to produce macroporous phenolic foam panels with a size of 400 mm × 400 mm × 50 mm. The density of the phenolic foams can be tuned from 0.44 g/cm3 to 0.18 g/cm3 by controlling the energy input into the liquid formulation, i.e. whipping speed and time. Accordingly, the phenolic foams had elastic moduli ranging from 200 MPa to 50 MPa. The phenolic foams were pyrolysed to produce carbon foams with a carbon yield of 48%. The carbon foams had an open porous structure replicating the phenolic foam precursor and electric conductivity of 17 S/m. Keywords: Phenolic foams, Froth templating, Carbon foams, Mechanical properties