Strain sensitive conductive polyurethane foam/graphene nanocomposites prepared by impregnation method

Conductive polyurethane foam nanocomposites were prepared by the incorporation of graphene flakes. Graphene flakes were obtained from graphite by the top-down method of liquid exfoliation in N-methyl pyrrolidone and size-selected by centrifugation. A deep characterization of graphene flakes was performed for a better understanding of their role as nanoentities in polyurethane foam matrix. Thus, morphology, with special emphasis in the number of layers, was analyzed by Raman spectroscopy, atomic force microscopy and transmission electron microscopy. Electrostatic force microscopy was used to verify the conductive nature of graphene flakes. This technique showed to be effective for the assessment of both morphology and conductive properties of graphene flakes. Regarding the electrical behavior of the nanocomposite foams, it was determined that the electrical resistance depended on both the graphene content and the compressive deformation applied to the material.