Elastic percolation of swollen polyacrylamide (PAAm)–multiwall carbon nanotubes composite

Abstract

Polyacrylamide (PAAm)–multiwalled carbon nanotube (MWNT) composites were prepared via free radical cross-linking copolymerization with different amounts of MWNTs varying in the range between 0.1 and 50 wt%. The mechanical properties of swollen PAAm–MWNT composites were characterized by the tensile testing technique. A small content of embedded nanotubes dramatically changes the compressive elastic modulus of the composites. Compressive elastic modulus dramatically increases up to 1 wt% MWNT on increasing nanotube content, and then decreases, presenting a critical MWNT value, indicating that there is a sudden change in the material elasticity. The critical exponent, y of elasticity, below the critical MWNT content, 1 wt%, is found to be 0.58, which is consistent with the suggestions of percolation in the superelastic percolation network for PAAm–MWNT composite.