ABSTRACT
Abstract Polyimide foam nanocomposites have been developed through an in situ polymerization process followed by solid state powder foaming. The dispersion of the acid functionalized multi-walled carbon nanotubes in the reaction medium is achieved by means of surfactants, mechanical mixing and sonication. In the last step of the dispersion technique, a solution of carbon nanotubes in tetrahydrofuran is sonicated with the diamine monomer in order to improve carbon nanotube dispersibility by favoring the interaction of the acid functionalities of carbon nanotubes and the basic amine groups of diamine monomers. The carbon nanotube dispersion is used as the reaction medium for the polymerization of diamine and diester monomers, giving rise to a poly(amic acid)–carbon nanotube solution. Partial solvent volatilization produces solid poly(amic acid) with embedded carbon nanotubes that is processed to a powder. Polyimide foam is produced from poly(amic acid) powder after a thermal treatment termed ‘solid state powder foaming’. Differential scanning calorimetry and thermo-gravimetric analyses have been used to determine optimal processing conditions and the influence of different surfactants. An analysis of the influence of carbon nanotubes on the polyimide matrix has been carried out to fully understand the nature, properties and behavior of this type of material.
